1. Anatomy Of A Bone (10 Files Merged).pdf

What Does Bones Do ..? • The bones of the skeleton provide structural support for the body. • Permit movement and locomotion by providing levers for the muscles. • Protect vital organs.  maintenance of mineral homeostasis and acidbase balance.  Serve as a reservoir of growth factors and cytokines.  Hematopoiesis within the marrow spaces

Structure of a long bone

Compact bone

Spongy bone – Trabeculae (oriented to give mechanical strength) – Interior of long bones, skull bones – Epiphyses of long bones – Intramembranous ossification (osteoblasts lay down bone around blood vessels in connective tissues of dermis (after 8 weeks of development)

• GH from anterior pituitary, which is regulated by T3 and T4 of the thyroid • During puberty- sex hormones: estrogen and testosterone • Hyposecretion of GH- dwarfism • Hypersecretion of GH- gigantism

REGULATION OF ENDOCHONDRAL OSSIFICATION • Systemic factors growth hormone thyroid hormone • local factors: Indian hedgehog, parathyroid hormone-related peptide. fibroblast growth factors and the cartilage matrix components.

• chondrocyte-selective transcription factors • Transcription factors that play critical roles in regulation of chondrocyte gene expression under the control of extracellular factors include Runx2, Sox9 and MEF2C. • Matrix metalloproteinase family: invasion • presence of blood vessels and bone-resorbing osteoclasts

Endochondral Ossification 1. 2. •

Cartilage model Bone collar forms in diaphysis (dense bone) Cartilage chondrocytes in center of diaphysis die and cartilage disintegrates

Periosteal bud enters diaphysis Makes spongy bone at ends of diaphysis (primary ossification center)

1. 2.

Epiphysis begins to ossify (secondary ossification center) Hyaline cartilage remains only at Epiphyseal surfaces (articular surfaces of joints) Epiphyseal growth plates between diaphysis and epiphysis (primary and secondary ossification centers on either side)

Endochondral Ossification

Endochondral Ossification

Endochondral Ossification

2o ossification center

cartilage

calcified cartilage

bone Just before birth

epiphyseal plate Childhood

epiphyseal line Adult

Why Bone Remodel • Bone remodeling is the process by which bone is renewed to maintain bone strength and mineral homeostasis

Why do bones need to “remodel?”

Fracture repair

Types of Bone 

Lamellar Bone - Orderly cellular distribution  Collagen fibers arranged in parallel layers  Normal adult bone



Woven Bone or immature bone (non-lamella  Randomly oriented collagen fibers  In adults, seen at sites of fracture healing, tendon or ligament attachment and in pathological conditions

Lamellar Bone 

Cortical bone - Comprised of osteons (Haversian systems) runs longitudinally 

Osteons communicate with medullary cavity by Volkmann’s canals that run horizontally

Haversian System osteocyte

Haversian canal

osteon

Volkmann’s canal

Woven Bone 





Coarse with random orientation Weaker than lamellar bone Normally remodeled to lamellar bone

Bone Composition 

Cells  Osteocytes

 Osteoblasts  Osteoclasts 

Extracellular Matrix  Organic

(35%)

 Collagen

(type I) 90%  Osteocalcin, osteonectin, proteoglycans, glycosaminoglycans, lipids (ground substance)  Inorganic

(65%)

 Primarily

hydroxyapatite

Osteoblasts







Derived from mesenchymal stem cells Line the surface of the bone and produce osteoid Immediate precursor is fibroblast-like preosteoblasts

Osteocytes 



Osteoblasts surrounded by bone matrix  trapped in lacunae Function poorly understood  regulating bone metabolism in response to stress and strain

Osteocyte Network  





Osteocyte lacunae are connected by canaliculi Osteocytes are interconnected by long cell processes that project through the canaliculi Preosteoblasts also have connections via canaliculi with the osteocytes Network probably facilitates response of bone to mechanical and chemical factors

Osteoclasts 



 

Derived from hematopoietic stem cells (monocyte precursor cells) Multinucleated cells whose function is bone resorption Reside in bone resorption pits (Howship’s lacunae) Parathyroid hormone stimulates receptors on osteoblasts that activate osteoclastic bone resorption

Local Regulation of Bone Healing 

Growth factors Transforming growth factor

Bone morphogenetic proteins Fibroblast growth factors Platelet-derived growth factors

Insulin-like growth factors 

Cytokines Interleukin-1,-4,-6,-11, macrophage and granulocyte/macrophage (GM) colony-stimulating factors (CSFs) and Tumor Necrosis Factor

 

Prostaglandins/Leukotrienes Hormones

Transforming Growth Factor   



Super-family of growth factors (~34 members) Acts on serine/threonine kinase cell wall receptors Promotes proliferation and differentiation of mesenchymal precursors for osteoblasts, osteoclasts and chondrocytes Stimulates both enchondral and intramembranous bone formation Induces synthesis of cartilage-specific proteoglycans and type II collagen  Stimulates collagen synthesis by osteoblasts 

Bone Morphogenetic Proteins 



Osteoinductive proteins initially isolated from demineralized bone matrix Induce cell differentiation 



Promote endochondral ossification 



BMP-3 (osteogenin) is an extremely potent inducer of mesenchymal tissue differentiation into bone BMP-2 and BMP-7 induce endochondral bone formation in segmental defects

Regulate extracellular matrix production 

BMP-1 is an enzyme that cleaves the carboxy termini of procollagens I, II and III

Bone Morphogenetic Proteins 

These are included in the TGF-β family 

  

Except BMP-1

Sixteen different BMP’s have been identified BMP2-7,9 are osteoinductive BMP2,6, & 9 may be the most potent in osteoblastic differentiation 

Involved in progenitor cell transformation to pre-osteoblasts

Fibroblast Growth Factors  

 

Both acidic (FGF-1) and basic (FGF-2) forms Increase proliferation of chondrocytes and osteoblasts Enhance callus formation FGF-2 stimulates angiogenesis

Platelet-Derived Growth Factor 

A dimer of the products of two genes, PDGF-A and PDGFB 

  



PDGF-BB and PDGF-AB are the predominant forms found in the circulation

Stimulates bone cell growth Mitogen for cells of mesenchymal origin Increases type I collagen synthesis by increasing the number of osteoblasts PDGF-BB stimulates bone resorption by increasing the number of osteoclasts

Insulin-like Growth Factor 

  

Two types: IGF-I and IGF-II  Synthesized by multiple tissues  IGF-I production in the liver is stimulated by Growth Hormone Stimulates bone collagen and matrix synthesis Stimulates replication of osteoblasts Inhibits bone collagen degradation

Cytokines 



Interleukin-1,-4,-6,-11, macrophage and granulocyte/macrophage (GM) colony-stimulating factors (CSFs) and Tumor Necrosis Factor Stimulate bone resorption 

 

IL-1 is the most potent

IL-1 and IL-6 synthesis is decreased by estrogen Regulate endochondral bone formation

Prostaglandins / Leukotrienes  

Effect on bone resorption is species dependent Prostaglandins of the E series Stimulate osteoblastic bone formation  Inhibit activity of isolated osteoclasts 



Leukotrienes Stimulate osteoblastic bone formation  Enhance the capacity of isolated osteoclasts to form resorption pits 

Hormones 

Estrogen Stimulates fracture healing through receptor mediated mechanism  Modulates release of a specific inhibitor of IL-1 



Thyroid hormones 



Thyroxine and triiodothyronine stimulate osteoclastic bone resorption

Glucocorticoids 

Inhibit calcium absorption from the gut causing increased PTH and therefore increased osteoclastic bone resorption

Hormones (cont.) 



Parathyroid Hormone  Intermittent exposure stimulates  Osteoblasts  Increased bone formation Growth Hormone  Mediated through IGF-1 (Somatomedin-C)  Increases callus formation and fracture strength

Vascular Factors 



Metalloproteinases  Degrade cartilage and bones to allow invasion of vessels Angiogenic factors  Vascular-endothelial growth factors  Mediate neo-angiogenesis & endothelial-cell specific mitogens  Angiopoietin (1&2)  Regulate formation of larger vessels and branches

FRACTURE: ‘’ A fracture is a dissolution of bony continuity with or without displacement of the fragments. ‘’

Anatomy Of Bone

ETIOLOGY OF FRACTURE EXTRINSIC CAUSES 

DIRECT VIOLENCE

 Trauma is the most common cause of

fractures in small animals.  automobile injury, falling from a height.

INDIRECT VIOLENCE  More predictable than those due to direct trauma.  Generally a force is transmitted to a bone in a

specific fashion and at a "weak link" within the bone, causing a fracture to occur.  BENDING FORCES  TORSIONAL FORCES

when a twisting force is applied to the long axis of a bone.  COMPRESSION FORCES Compressive forces along the long axis of a bone, result in impacted fractures or compression fractures.

 BENDING FORCES  TORSIONAL FORCES  COMPRESSION FORCES

 SHEARING FORCES

SHEARING FORCES  A shearing fracture is caused by a force

transmitted along the axis of a bone, which is then transferred to a portion of the same bone that lies peripheral to the axis or across a joint to other bones that are not protected by the axis of the bone.  The force shears off that bony portion unable to continue transmission of the force along the axis

INTRINSIC

CAUSES

 FRACTURES DUE TO MUSCULAR ACTION

 Fractures caused by violent contraction of a muscle are called avulsion fractures  The processes commonly avulsed include the

acromion, scapular tuberosity, greater humeral tubercle, olecranon, ischial tuberosity, greater trochanter, tibial tuberosity, and the calcaneus of the fibular tarsal bone.

PATHOLOGIC FRACTURES Pathologic fracture. Fibrosarcoma of the distal femoral metaphysis in a dog

 Occur because of underlying

bony or systemic disease:  neoplasia, bone cysts, osteoporotic bone caused by secondary , nutritional hyperparathyroidism, localized bone infection (osteomyelitis), osteoporotic bone caused by disuse following prolonged external fixation or removal of a rigid internal device.

CLASSIFICATION OF FRACTURES BY TYPE  Based on the severity of the fracture.

 whether it communicates through the skin.  The shape of the fracture line .  The anatomical location of the fracture

within an individual bone. 

INCOMPLETE FRACTURES

 some portion of the bone remains intact.

GREENSTICK FRACTURE  Resembles the break

that results when a supple green branch of a tree is bent and breaks incompletely.

 FISSURE FRACTURE  Cracks or fissure lines will occur when direct trauma is

applied to any long or flat bone. Generally periosteum is intact.  Fissure lines : transverse, oblique, spiral, longitudinal, or radiating from a central point

 DEPRESSION FRACTURE The area on bone will depress from the direction of force. This usually occurs in the calvarium, the maxilla, or the frontal bone areas of the head.

COMPLETE FRACTURES  Complete loss of bony continuity, allowing

overriding and deformation.  Far more common than incomplete fractures.

TRANSVERSE FRACTURE  Fracture line is

transverse to the long axis of the bone.  Anatomical alignment is possible.

OBLIQUE FRACTURE  Fracture line is oblique

to the long axis of the bone.  This fracture tends to override or rotate unless traction is maintained throughout the period of healing.

SPIRAL FRACTURE  Fracture line spirals

along the long axis of the bone.  Reduction of spiral fractures is difficult without constant traction or internal fixation, since these fractures tend to override and rotate into deformity.

COMMINUTED FRACTURE  Three fracture fragments

at site of fracture.  The fracture lines interconnect may be transverse, oblique, or spiral.  Due to High-Energy trauma.  Difficult to reduce and fix because they have no inherent stability. Constant external traction and alignment or internal fixation is required.

MULTIPLE FRACTURE  Three or more fracture

fragments in a single bone.  The fracture lines do not interconnect.  Completely independent fractures affecting the same bone.  Requires separate reductions and fixations.

IMPACTION FRACTURE  Cortical fragment, is

forced or impacted into cancellous bone.  Typically at the ends of long bones.  This is an uncommon fracture in small animals.

COMPRESSION FRACTURE  Cancellous bone

collapses and compresses upon itself.  Typically occurs in vertebral bodies following trauma to the spine.  Rarely reduced, since the bone within the fracture area has been destroyed by the crushing.  These fractures are stable and heal in place.

CLOSED FRACTURE  Fracture remains

encased within the skin and musculature that surround it.  Does not communicate with the outside environment.  Most fractures in animals are closed.  A synonym found in older literature is "simple fracture".

OPEN FRACTURE  Communicates with

the outside environment.  Potential contamination of fracture .  A synonym found in older literature is "compound fracture."

CLASSIFICATION OF FRACTION BY LOCATION  Fractures may be classified by their

anatomical location in relation to a specific bone.  Identifying a fracture by location does not indicate whether the fracture is open or closed, nor does it indicate the type of fracture: transverse, oblique, spiral, or the like.  These systems are compatible and should be used together.

DIAPHYSEAL FRACTURE  Fractures of the diaphysis are referred to by breaking the diaphysis into equal thirds. Therefore, fractures can be proximal third,

middle third, or distal third of the diaphysis  Mid shaft if it occurs near to axial center of bone.

METAPHYSEAL FRACTURE  Any fracture within the

anatomical metaphysis of a long bone is referred to as a metaphyseal fracture.  They heal rapidly since cancellous in nature

FRACTURE OF THE EPIPHYSEAL PLATE  Occurs in immature animals during the time

that the epiphyseal plate remains open and cartilaginous.  Fracture occurs through the zone of hypertrophied cartilage cells.  Proximal or distal epiphyseal plate or both may be affected .

PHYSEAL FRACTURES

Salter- Harris classification Type  I:  II:  III:  IV:  V:

What is Broken Off The entire epiphysis Entire epiphysis + portion of the metaphysis Portion of the epiphysis Portion of the epiphysis + portion of the metaphysis Nothing “broken off;” compression injury of the epiphyseal plate

Salter- Harris classification  Type I-Epiphyseal separation: there is displacement of the

epiphysis from the metaphysis at the growth plate.  Type II-A small corner of metaphyseal bone fractures and

displaces, with the epiphysis displaced from the metaphysis at the growth plate.  Type III-Fracture is through the epiphysis and part of the growth

plate, but the metaphysis is unaffected.  Type IV-Fracture is through the epiphysis, growth plate, and

metaphysis. Several fracture lines may be seen.  Type V-Impaction of the epiphyseal plate occurs, with the

metaphysis driven into the epiphysis.

EPIPHYSEAL FRACTURE  In the mature animal with closed growth

plates, fractures of the epiphysis are termed epiphyseal fractures.  They may be of the proximal or distal epiphyseal fractures.

CONDYLAR FRACTURE  Condylar fractures occur

in mature animals and affect the distal ends of the humerus or femur, or the proximal tibia.  Supracondylar; supracondylar/intercond ylar fracture and may be classified as a "V," "Y," or "T" fracture to better describe the shape of the fracture lines.

ARTICULAR FRACTURE  The subchondral bone and articular cartilage

are involved in the fracture.  The term periarticular fracture could be replaced by epiphyseal fracture.  Requires perfect anatomical reduction and fixation to prevent secondary degenerative joint disease.

AVULSION FRACTURE  Intrinsic etiology.  Generally caused by muscular 

  

contraction. The prominences that fracture are usually separate centers of bone formation referred to as apophyses. Avulsion of the greater trochanter. Displace in the direction of the muscle pull that caused the fracture. Difficult to reduce and fix requires constant traction or internal fixation.

FRACTURE-DISLOCATION  Describes joint fractures

that produce joint instability simultaneous subluxation or luxation of the affected joint.  Difficult to treat because they represent intraarticular fracture plus supprting tissue laxity.  Prognosis is poor.

FRACTURE-DISLOCATION  Describes joint fractures

that produce joint instability simultaneous subluxation or luxation of the affected joint.  Difficult to treat because they represent intraarticular fracture plus supprting tissue laxity.  Prognosis is poor.

DIAGNOSIS OF FRACTURE  Clinical signs

 Orthopaedic examination  Dysfunction  PAIN:Pain over the site of fracture is

common. In incomplete fractures this may be the only clinical indication.  During local tissue shock, that is, within 20 to 30 minutes after the accident, pain may not be a conspicuous sign.

 LOCAL TRAUMA

Swelling, hematoma, contusion, or laceration  ABNORMAL POSTURE Deviation from the normal anatomical structure. The displacement of bone fragments may be angular, longitudinal, or rotational.  CREPITUS Crepitus is a pathognomonic sign of fracture. Pseudocrepitus seen in case of arthritis, partial luxations of the patella, or luxations of the coxofemoral joint.  ABNORMAL MOBILITY A false point of motion is seen in complete fracture.

 OTHER SIGNS

 Fever-. Breakdown of haematoma leads to elevated temperature seen 24 to 48 hours following a fracture  Anemia  Shock  Nerve injury  Necrosis or gangrene.

PATHOLOGY ASSOCIATED WITH FRACTURE  

    

soft tissue injuries. Laceration of the bladder, prostate, pelvic urethra, or major vessels and nerves. Hemothorax, pneumothorax, or laceration of the lung parenchyma. Skin, muscles, periosteum, tendons, nerves, and vessels may be damaged. Systemic affects like shock. The brain or spinal cord may be contused. Fat embolization produce respiratory difficulty. Ruptured abdominal organ may result in blood loss sufficient to cause death.

APPICATION OF EXTERNAL AND INTERNAL IMMOBILISATION OF FRAFCTURES IN SMALL AND LARGE ANIMALS

• Fracture Reduction: It is a process of Reconstructing fractured Bones to their normal Anatomic configuration. NORMAL LIMB ALIGNMENT ACHIEVED BY 1. Restoring Normal Limb Length 2. Maintaining Spatial Orientation 3. Restoring Alignment of Joints

• PRINCILES OF FRACTURE REPAIR: • “ 4 R” FOUR R SHOULD be considered during fracture Repair. • A. RECOGNITION: Diagnosing the type and site of fracture manually and Radiographically. • B. REDUCTION: Alignment of fractured segments in their Original anatomic position. Muscle relaxation and alignment and apposition of fracture segments mandatory. • C. RETENTION: Fracture fragments are immobilised by external and or internal methods. • D. REHABILITATION: Returning of affected limb to Normalcy for early ambulation by Physiotherapy.

FRACTURE REDUCTION:

A) CLOSED REDUCTION B)OPEN REDUCTION CLOSED REDUCTION: DEF: Reducing fracture ,aligning Limbs without surgically exposing Bones. ACHIEVED BY: 1. Application of Traction and Counter traction, Bending and Levering and other manipulative procedures. 2. Muscle relaxation by a)Balanced Anaesthesia b) Hanging limb Technique c) Use of Gordon extendor

Advantages: 1. Preservation of soft tissues and Blood supply which speed healing. 2. Decreased possibility of Inducing Infection 3. Reduced operating time 4. Less Manipulation 5. Simple to Perform 6. Minimum complications

• Disadvantages: 1. Difficulty of Gaining Accurate Reduction without visualisation of fracture segments and fragments. 2. Difficult to reduce Old Fractures, Unstable fractures and Complicated fractures. OPEN REDUCTION: DEF: Surgical approach to expose fracture Bone segments and fragments for so anatomically reconstructed and held in position with orthopaedic implants. OPEN REDUCTION IS ACHIEVED BY : 1. Application of Traction, Counter traction, Rotation ,Levering with bone forceps , Osteotomes and other Equipment.

GUIDE LINES FOR OPEN REDUCTION: A. Gentle Handling of Tissues. B. Follow Normal muscle separation. C. Avoid cutting major blood vessels and Nerves. D. Preserve soft tissue Attachments to the bone E. Bone holding forceps and muscle retractors used for exposure of fracture segments. Advantages: Method of choice in many cases . Used in high percentage of fracture cases Unstable, Complicated, old fractures and fractures involving articular surfaces.

2. Visualisation and Direct contact with bone fragments facilitates anatomic fracture Reconstruction. 3. Direct Placement of Implants i.e. I/M Pins / Cerclage Wires/ Lag screws and Bone Plates. 4. Bone Reconstruction allows Bone and Implants to share Loads Resulting in Stronger fracture fixation. 5. Cancellous Bone Grafts can be used to enhance Bone Healing. DISADVANTAGES: 1. Increased surgical trauma to soft tissues and Blood supply. 2. Greater Opportunity to introduce Bacterial contamination.

• Fracture Repair in small animals divided in to 2 categories. • 1 Closed reduction: • a)External support or External coaptation • EXTERNAL COAPTATION IS DEFINED AS LIMB SPLINTING • b)Closed reduction with Intramedullary pinning + External immobilisation

• 2. Open Reduction: • a) INTRAMEDULLARY FIXATION alone. • b) INTENAL FIXATION + External support

• INTENAL FIXATION OF A FRACTURE MAY BE BEST DEFINED AS BONE SPLINTING.

EXTERNAL IMMOBILISATION 1. Gum bandages 2. Starch bandages 3. Splints and bandages 4. Plaster of Paris 5. Plaster of Paris splints and gutters 6. Poroplastic felt 7. Thomas splints 8. Mason meta splints 9. Aluminium splints. 10. Fibre glass cast 11. Orthoplast

12.Wooden or Bamboo splints 13.External Skeletal Fixators. 1.Gum bandages: used for immobilising fractures in birds. 2. Starch bandages: for fractures in small animals. 3. Splints and bandages: Light metal or wooden sticks. It is necessary to include both the joints above and below the fracture for immobilisation with splints. 4. Plaster of Paris: It can be easily and accurately moulded to the contour of the limb but it is heavy, slow setting time ,impervious to fluids and resented by dogs.

• COMPLICATIONS: • Removal by Patient BY Chewing and or biting as it causes irritation. • uneven pressure interfere with circulation and results in swelling of foot. • Excoriation of skin at the extremities. • Need frequent examination of limb.ie immediately after 24 hrs and periodical check up by radiographs at 15 days 30 days and 45 days. • if it become loose it needs to be reapplied.

• Fibre glass cast: • Fibre glass resin – impregnated cast is a new synthetic material that replaced plaster material. • It is light weight , impact resistant and radiolucent. • The material hardens quickly and attains maximum strength in short time. • water proof stockinetee be used to wrap the limb before application of cast otherwise water may seep in to the skin due to porous nature of material. • OTRHOPLAST: • Thermally sensitive plastic such as Ortho plast combine – such as • Malleability, strength ad cohesiveness in the construction of splints of various applications.

MASON MRTASPLINT

• Thomas splint:

Dr. Stader was first to design the First Veterinary external splint. Def : External skeletal fixation is used to stabilise Bone segments or joints with percutaneous wires or Pins held together by an external frame. Indications: 1.Closed fractures , 2. open fractures, 3.comminuted fractures 4.compound fractures, 5.Limb deformities, and Corrective Osteotomies 6. Non unions > a. Hypertrophic non unions. b. Atrophic non- unions

7. Stabilisation of Joints during healing of luxation and after ligament or tendon reconstruction. 8. Fusion of certain joints (Arthrodesis). 9. Limb lengthening procedures. 10.Mandibular fractures.

• Advantages: 1. Offer adjustability after surgery is an advantage over 1. Plate fixation. Frames adjusted or reinforced in the post operative period. 2. Less invasive than Plate fixation.  3. Allows better access to wounds than external Coaptation. 4. Ease of application. 5. Tolerance by dogs and cats. 6.Adequate fixation of fracture with out presence of metal implant at the fracture site

Disadvantages: pin tract infection and discharge  Breakage of pins.  pin loosening.  Radiographs should be taken at 3wks ,4wks and 6wks intervals post operatively to evaluate fracture healing.

• COMPONENTS OF EXTERANAL FIXATOR: • 1.FIXATION PINS • 2.CONNECTING BARS • 3.CLAMPS • FIXATION PINS: Steinmann pins, end threaded pins or middle threaded pins are used • Must penetrate both first and second cortices of bone or( near and far cortex) • Half pins or Half pin splintage: If the fixation pin penetrates only one skin surface and two bone cortices it is called Half pin. • Full pins or full pin splintage : Fixation pins penetrate two skin surfaces and two bone cortices are called

HALF PIN SPLINTAGE –TYPE I a

• CONNECTING BARS: connecting bar or rod functions to connect the fixation pins attached to the bone fragments. • Connecting bars or rods are available in stainless steel, Carbon fibre, aluminium, Titanium and Acrylic material. • CLAMPS: Connect fixation pins to external bar. • SINGLE CLAMPS OR DOUBLE CLAMPS Splint or Frame consist of fixation pins and clamps connected by clamps. Where as bone and entire frame together is referred to as MONTAGE OR CONSTRUCT

• CLASSIFICATION OF FRAME CONFIGUATIONS. • TYPE Ia is Unilateral- uniplanar:  fixation pins (Half pins) are used in one plane of bone and connected by single bar. Applied to the medial surface of the radius and tibia and the lateral surface of the femur and Humerus using Half pin trasfixation pins. • TYPE Ib is Unilateral- Biplanar: Fixation pins (Half pins)are used in two planes of the bone and connected by connecting bars. Applied most commonly to the radius and tibia on two planes.

TYPE II is bilateral-uniplanar 1. Trans fixation pins are placed in one plane of bone. •

2. First place full pins in the proximal and distal end of bone so that they lie in the same plane.  3. Place the pins perpendicular to the bone and parallel to the joint surfaces to facilitate limb alignment.  4. Later the intermediate pins are placed through the preplaced clamps in to the both the fracture fragments of bone

TYPE II UNIPLANAR BILATERAL CONFIGURATION OF ESF

TYPE II UNIPLANAR BILATERAL

TYPE III bilateral biplanar. : combination of bilateral and uniplanar type II PLUS Unilateral and uniplanar type I _====(i.e Type II +Type I )

TIE IN CONFIGURATION: connects External fixator with an IM pin used for fractures of femur and Humerus.  Type II and Type III full pins Apply to Radius and tibia but not to the femur and humerus because of the body wall.

HALF PIN( TYPE Ia + IM PIN)

• CIRULAR FIXATION METHODS: Fixation pins are connected by circular rings to form a rigid circular frame. • Offers Unlimited Geometric adaptability. • HYBRID FRAMES : Linear and circular frames are combined to form Hybrid circular system. • Tied in configuration: IM pin + Linear External fixator is used for femur and Humerus. • Type ii and type iii are applicable only below the stifle and elbow .

TYPE II ESF

CIRCULAR FIXATORS

• PRINCIPLES OF APPLICATION:  strict asepsis  Ensure normal anatomical reduction  pin must penetrate both cortices of bone  pins passed perpendicular to the bone and lie parallel to the joint line  First pin passed first in to the proximal end and second pin next in to the distal end of bone.  After reduction, the intermediate pins are placed in to the fracture segments.

TYPE II ESF

TYPE I UNIPLANAR UNILATERAL

TYPE I ESF

TYPE I a ESF

Type ii uniplanar bilateral

circular type

Hybrid fixators

Type I ESF

 the pins are connected to the side bars and fixed with clamps  insert pins with out causing thermal necrosis.  Avoid soft tissue damage.  use pins of size not more than 25% of the diameter of the bone  Most common technique of application is type I and type II  Type I frames are least stiff. Type II frames are used for radial and tibial , ulnar fractures. Type II are 100% stiffer than Type I  Frames type III Biplanar fixators are stiffer than Uniplanar fixators.

• COMPLICATIONS OF ESF : • Pint tract infection and discharge • Pin tract sequestra • loosening of fixator • Bending of trans fixation pins • Iatrogenic fracture. • Client Education • Restrict activity • Leash walk • Avoid fencing which may catch or tangle the frame • Inspect the frame for loosening and any discharge from the pin bone interface

Restricted activity to for additional 6-8 wks following removal of fixator

Fracture forces : There are fracture forces acting on the fracture site. It is necessary to consider these forces when selecting an implant. 1. Axial compressive forces 2. Axial Tension forces or Distraction forces 3. Bending forces 4. Torsional/Rotational forces.

1. Axial compressive forces :

1. Axial Tension forces or Distraction forces :

2. Bending forces :

4 Torsional/Rotational forces:

INTERNAL FIXATION METHODS OF IMMOBILISATION OF FRACTURES IN ANIMALS 1. 2. 3. 4. 5. 6. 7. 8.

INTRAMEDULLARY PINNING. RUSH PINNING KUNTSCHER NAILING INTERLOCKING NAILING BONE PLATING ORTHOPEDIC WIRING -CERCLAGE AND HEMICERCLAGE WIRING TENSION BAND WIRING BONE SCREWS

9.INTERFRAGMENTARY COMPRESSION. LAG SCREW PRINCIPLE 10. INTRAMDULLARY PIN + EXTERNAL FIXATOR : where intra medually pin of 50 % diameter of medullary canal is inserted in to the medullary canal by open method and tied to the external fixator of type I placed on the lateral aspect of either femur or Humerus. This is called tie-in method. • intramedullary pin resists the bending forces and external fixator counteracts the rotational or torsional forces. 11. STACK PLATING: when more than one plate is used for fracture immobilisation is called stack plating. ex: veterinary Cuttable plates. 12. CROSS PINNING. 13. PLATE ROD TECHNIQE

• INTRMEDULLARY PINNING: • MOST COMMONLY USED INTERNAL FIXATION DEVICE. • Steinmann pins, K-wire , Rush pin and Kuntschner nail are used • STEINMANN PINS: • Jacob chuck and key and Bone holding forceps required for driving pin in to medullary canal. • Double pointed or single pointed • Chisel, Trocar, or threaded ends • Smooth rounded and larger diameter pins. • Fill at least 70% of medullary canal. • Neutralise or Resist or counter the Bending forces • but can not resist the Rotational forces

• Indications: Diaphyseal fractures of Long bones • Stable ----Transverse and short oblique fractures. • In unstable fractures such as Long oblique and spiral and comminuted fractures > IM pin combined with Cercalge wire is used

• Used as single pin • Double pins: two pins are used • stack pinning or Multiple Pinning: More than two pins are used in the medullary canal • Mostly used for fractures of Long bones

 Used alone  in combination with wires ie IM pin + Cerclage wire for long Oblique or spiral fractures. IM pin + ESF type I = Tie in method used for femur and humerus.  IM pin + Bone plate = plate rod Method  used by Open or Closed Method depending on the case.  Healing takes place by periosteal bridging callus

•

:

• Normo grade pinning: The pin is driven from one end of bone to the other end. By closed method.

• Sites: • 1.For fractures of femur pin is driven through the trochanteric fossa • 2.For humerus – ¼ inch below the ridge on the lateral tuberosity. • 3.For Tibia -1/4 inch below the medial meniscus and between the anterior and medial tuberosities.

• Retrograde pinning: • The pin is driven in to the medullary canal of the proximal segment from the fracture site by the manual chuck till comes out of the trochanteric fossa.

• This is done by open method for exposing the fractures site

INTRAMEDULLARY FIXATION NORMOGRADE RETROGRADE

• Open Method: The seat of fracture is opened by a surgical procedure. • By the use of a chuck the pin is first driven in to proximal fragment until the upper end of the pin comes out through the skin. • Now the chuck is disconnected and is fixed on to the upper exposed end of the pin in order to drive the pin in to the distal segment until it firmly placed in to the sub-chondral bone. • The excess portion of the pin is cut and removed. • the pin is removed after healing.

• Advantages: it is easy to apply , economical , less invasive compared to plating and used in combination with wiring and ESF and Pates. • Neutralises the Bending forces at the fracture. • it is indicated for fixation of stable fractures such as transverse fracture and short oblique fractures. • Disadvantages: it can not neutralise the torsional or rotational forces at the fracture site. • It can not be used alone for fixation of unstable fractures such as long oblique, comminuted, or segmental fractures with out • any auxillary support of wiring and other external or internal methods of fixation

RUSH PINNING INDICATIONS: supracondylar fractures of femur and Humerus. principle: Immobilises the fracture by three point fixation under spring loaded tension. Materials: Rush pins 2 in number, awl to start a guide hole, a mallet and a driver-extractor. Inserted at an acute angle of 30 -40 degrees to the long axis of bone, passing obliquely through the cancellous bone of the distal fragment and in to the medullary activity.

K -WIRES • Small diameter pins. • Act to counter bending forces • Relatively weak except in small patients • To counter rotational forces the K- wires are best placed parallel to each other. Ex to fix the supracondylar fractures and avulsion or distraction fractures ie fractures of Olecranon and anterior tuberosity of tibia and Trochanteric fractures

• KUNTSCHER NAILE • A clover leaf or V shaped hollow nail. One end of the nail is sharpened for impaction and at the other end there is a hole to engage an extractor hook. • indications: Transverse fracture of femur and humerus. • Inserted at the extremity of bone and then driven down the medullary canal • the shape of the nail completely impacts the medullary canal and pointed end ensures good grip in the cancellous bone. It resists or neutralises the rotational forces at the facture site.

INTERLOCKING NAILING Indications: Used for diaphyseal fractures of femur and tibia. Interlocking nails act as an internal splint for fracture for long bones and functions most effectively to control bending forces and prevent rotational forces. • Indications and Biomechanical Principles : • Interlocking nails are inserted in the medullary canal and locked in place with screws or cross-locking bolts placed through the proximal and distal fracture segments. • Resist all the forces acting on fractures (nail - bending support, locking bone screws or bolts - axial and rotational support).

INTERLOCKING NAILS

CROSS PINNING

• Steinmann pins or Kirschner wires used as crossed pins for repair of physeal or metaphyseal / supracondylar fracture of femur and humerus

• Take care - pins should cross above the fracture line. • Check the fracture stability and pin position.

• ORTHOPEDIC WIRING -CERCLAGE AND HEMICERCLAGE WIRING • ORTHOPEDIC WIRE

• It is used in combination with other orthopedic implants to supplement axial, rotational, and bending support of fractures.

Indications and Biomechanical Principles • Used either to provide stability to anatomically reconstructed long oblique or spiral fractures or to hold multiple fragments in position. • To accomplish this, three criteria must be met: • (1) the length of the fracture line should be two to three times the diameter of bone. At least two wires are used.

• CERCLAGE WIRE : Fully encircles a bone to hold fragments apposed. Used for long bone fractures of Diaphysis. • HEMICECLAGE WIRE: Passed through half of the bone to maintain alignment while definitive fixation is applied. • INTERFRAGMENTARY WIRING: Used more often placed between fragments of Mandible or Maxilla. Ex: INTER DENTAL WIRING

ORTHOPEDIC WIRE Application • Use only on anatomically reconstructed long oblique or spiral fractures. • Use 18-gauge wire for large dogs and 22-gauge or 20-gauge wire for cats and small dogs. • Place two to three cerclage wires per fracture line. • Place wires perpendicular to the long axis of the bone. • Space wires- one half to one bone diameter apart. • Support cerclage wires with an IM pin, interlocking nail, external fixator, or plate.

TENSION BAND WIRING Indications: 1. Tibial tuberosity 2. Greater trochanter of the Femur 3. Greate tubercle of humerus 4. Scapular acromion process 5. supra glenoid tubercle 6. Olecranon.

Biomechanical Principles : • Tension is the predominant force --- which cause Avulsion Fractures. which cause Avulsion or Distraction of fractures segments

• The most effective way to resist tension is through application of a tension band. • It is placed to oppose the pull of a muscle or Ligament on a Bone fragment. • The purpose of a tension band is • To convert distractive tensile forces or tesnsion into compressive forces

TENSION BAND WIRE METHOD

Equipment :

Equipment includes 1. small Steinmann pins or 2. Kirschner wires and orthopedic wire. • A high-speed wire driver is preferred for placing the Kirschner wires.

• The orthopedic wire is secured with a wire tightener.

TENSION BANDS Application

• Use two Kirschner wires or small Steinmann pins. • Place wires parallel to each other and perpendicular to the fracture. • Seat the wires in the opposite cortex. • Place the hole for the orthopedic wire the same distance below the fracture as the pins are inserted above the fracture. • Tighten the wire in figure of eight 8 fashion so it resists pull of the opposing fragment.

INTERFRAGMENTARY COMPRESSION • Inter fragmental compression is a method of compressing two fragments of bone together and is achieved by the LAG SCREW PRINCIPLE. • Lag screw principle is not a specific screw but a way of placement to compress the two fragments together. • the technique requires Glide hole and Thread hole • fully threaded cortical screw or cancellous screw • 1.fully threaded or 2.partially threaded.

• Primary function of Lag Screw : provide fragment apposition through inter fragmentary compression. • APPLICATION: • Create a glide hole in the near fragment. • Diameter of the glide hole is as large as outer diameter of the screw. • while a small diameter pilot hole is drilled in the far cortex or far fragment

The thread glides through the glide hole in the near cortex and threads get engaged opposite cortex in the thread hole.

As the screw is tightened the two fragments are drawn together producing inter fragmentary compression. the screw should be placed perpendicular or right angles to the fracture line and will give maximal inter fragmental compression.

BONE PLATES • Bone plate counter acts all the fracture forces: Bending, rotational, shearing and tensional forces. Apposes the fragments. • sites: plates are usually placed • tibia – Medial aspect • Femur – Lateral side • Humerus- Medially, laterally and cranially depending on the fracture location. • Radius – Cranially • Ulna – Caudally, Laterally and Medially.

• Place plates on the tension surface of long bone. Plating the tension side counters the force pulling the fracture apart. • Plates may be inserted to function as • a compression plate ( Tension band Plate): when the plate is applied so that it is under tension and the fracture fragments are under compression it is referred to as a compression plate or a tension band plate. • a neutralisation plate: Applied on the tension side of the bone to neutralise or overcome torsional, bending, compressive and distraction forces on fracture lines that have been stabilised by interfragmentary compression. • bridging plate or a buttress plate.

• APPLICATION OF BONE PLATE: • An absolute minimum of two screws should be used in the bone segments on each side of the fracture. • minimal distance between screw hole and fracture line should be 4 to 5 mm. • plate need to be contoured to closely fit the bone surface. • SPECIAL PLATES : • Veterinary cuttable plates (VCP) • Limited –cantact Dynamic compression plates( LC-DCP) • Dynamic compression plates(DCP).- More versatile and popular implant • Reconstruction Plates.

• The traditional round hole plates:  sherman , Lane , Venable and Burns etc  Straight plates, Tubular plates and semi tubular plates( Tension band plates) and Malleable Templates

Indications for Plate removal:  once the fracture has healed and the implant becomes redundant.  Persistent sinus formation over the plate associated with low grade infection.  Thermal conduction and lameness  soft tissue irritation / Lick granuloma  Plate becomes non-functional

BONE SCREWS • Cortical screws: Fully threaded and used in compact cortical bone • Cancellous screw: either completely or partially threaded and used primarily in the epiphysis or Metaphysis. • PLATE SCREWS : are bone screws used to anchor bone plates to bone. • POSITION SCREW: are Bone screws used to hold bone fragments in place. Inserted through a plate hole or placed in bone independent of the plate. • Lag screws also called compression screws apply compression between fragments.

INTERNAL FIXATION METHODS OF FRACTURES

Objectives • To know the indications of internal fixation of fractures. • To learn the benefits of internal fixation methods of fractures. • To undestand the biomechanical principles of various internal fixation devices. • To familiarize with the equipment & supplies of various internal fixation devices • To describe different methods of application of internal fixation methods of fractures.

FRACTURE Fracture is a medical condition in which there is a breach in the continuity of a bone. Abbreviated as FRX, Fx or #.

Fractures are usually associated with soft tissue damage of varying degree.

Indications for Internal Fixation • Displaced intra-articular fracture • Axial, angular, or rotational instability that cannot be controlled by closed methods • Open fracture • Polytrauma • Associated neurovascular injury

Benefits of Internal Fixation • Earlier functional recovery • More predictable fracture alignment • Potentially faster time to healing

INTERNAL FIXATION METHODS • • • • • •

1. INTRAMEDULLARY FIXATION Intramedullary pins & Kirscher wires Interlocking nails Tension bands 2. PLATE & SCREW FIXATION Bone Plates ( Neutralization plate, Bridging plate,

Buttress plate & Locking plate) • Screws (Lag screw, Position screw, Plate screw & Locking screw)

INTRAMEDULLARY FIXATION • INTRAMEDULLARY PINS AND KIRSCHNER WIRES • Indications and Biomechanical Principles : • (IM) pins are used for diaphyseal fractures of the humerus, femur, tibia, ulna, and metacarpal and metatarsal bones. • IM pins are contraindicated for the radius. • The biomechanical advantage of IM pins is their resistance to applied bending loads.

INTRAMEDULLARY FIXATION • Biomechanical disadvantages of IM pins include poor resistance to axial (compressive) or rotational loads and lack of fixation (inter-locking) with bone. • The only resistance to rotation or axial loads provided by an IM pin is friction generated where pin and bone contact.

INTRAMEDULLARY FIXATION • IM pins should be supplemented with other implants (e.g., cerclage wire, external fixator or plate) to provide rotational and axial support. • Steinmann pins or Kirschner wires may be used as crossed pins (wires) or placed in a triangulated pattern to stabilize metaphyseal and physeal fractures in young animals.

Equipment and Supplies • IM pins are smooth, round, 316L stainless steel rods. • Steinmann pins - sizes (1/16 to ¼ inch ), point designs. • Single armed or double armed. • Point designs - trocar points and chisel points.

Equipment and Supplies • Smooth or threaded • Stress concentrator - predisposes to premature pin bending or breakage. • Kirschner wires - 0.035-inch to 0.062-inch diameter smooth pins with trocar points on each end. • Jacobs chuck - High-speed wire driver.

INTRAMEDULLARY FIXATION • Select a pin sized 60% to 70% of the medullary canal width along with auxillary device cerclage wire. • Select a pin sized 50% to 60% of the medullary canal width to pair with an external fixator. • Select a pin sized 40% to 50% of the medullary canal width to pair with a plate.

INTRAMEDULLARY FIXATION NORMOGRADE - RETROGRADE

INTRAMEDULLARY FIXATION • Span the length of the bone with the IM pin. • Use retrograde or normograde pin insertion in the lateral tuberosity of humerus and trochanteric fossa in femur. • Use normograde pin insertion ¼ inch below medial meniscus between anterior and medial tuberosity in the tibia. • Check pin location in the bone marrow with reference pin and by manipulating the joint. • Always use additional fixation to control rotation and axial loading.

CROSS PINNING • Steinmann pins or Kirschner wires - crossed pins - physeal or metaphyseal fracture. • Take care - pins should cross above the fracture. • Check the fracture stability and pin position.

INTERLOCKING NAILS

INTERLOCKING NAILS • Indications and Biomechanical Principles : • Interlocking nails are inserted in the medullary canal and locked in place with screws or crosslocking bolts placed through the proximal and distal fracture segments. • Resist all the forces acting on fractures (nail bending support, locking bone screws or bolts - axial and rotational support).

INTERLOCKING NAILS • Used effectively in animals with high and medium fracture assessment scores. • Used primarily for mid diaphyseal humeral, femoral, or tibial fractures (radius). • Available in various sizes and lengths. • Normal cortex should be sufficient proximal and distal to the fracture to allow insertion of two screws in each segment.

INTERLOCKING NAILS • Screws should be placed at least 2 cm from the fracture line to prevent excessive forces on the nail. • Inter-locking nails are weakest at the screw hole. • Fatigue failure • Solid cross-locking bolts may be used to minimize the occurrence of locking screw failure.

INTERLOCKING NAILS • • •

•

Equipment and Supplies Interlocking nails - 4, 4.7, 6, 8, and 10 mm in diameter, with five or six lengths available in each size. Each nail has three or four screw holes (upto two in each end), and they may be 11 or 22mm apart. The distal end may be a trocar or blunt point, and the proximal end has an internally threaded hole and two alignment tabs, to which an extension piece can be attached. An insertion tool is attached to the extension piece to insert the nail in a normo-grade direction.

INTERLOCKING NAILS • A drill-guide jig is then attached to the extension piece and used to align the drill bit with the holes in the nail. • The appropriate sized cortex bone screws or locking bolts are needed for each size nail. • The cross locking bolts are solid bolts with self-tapping positive profile threads below the head of the bolt. • The solid intersection provides greater resistance to failure. • The bolts are cut to an appropriate length before application.

INTERLOCKING NAILS

INTERLOCKING NAILS Application

• Use the largest nail that fits in the bone. • Span the length of the bone with the nail. • Ream the medullary canal with a Steinmann pin or use the reamers. • Insert the nail in a normograde fashion. • Position the nail so the holes are 2 cm away from the fracture. • Secure the nail with four screws or fixation bolts for optimal fixation.

ORTHOPEDIC WIRE

ORTHOPEDIC WIRE Cerclage and Hemicerclage Wire

• It is used in combination with other orthopedic implants to supplement axial, rotational, and bending support of fractures. • Cerclage wire in combination with Kirschner wires. • Cerclage wire has two distinctions.

ORTHOPEDIC WIRE Indications and Biomechanical Principles • Used either to provide stability to anatomically reconstructed long oblique or spiral fractures or to hold multiple fragments in position. • To accomplish this, three criteria must be met: • (1) the length of the fracture line should be two to three times the diameter of the marrow cavity, • (2) there should be a maximum of two fracture lines, and • (3) the fracture must be anatomically reduced.

ORTHOPEDIC WIRE • Common cause of cerclage wire failure - multi fragmented fractures. • When wire is misused, probable outcomes include collapse of the fracture, loss of stability, and wire loosening, which further delay healing. • Methods of tightening (loop versus twist) and (single wrap versus double wrap).

ORTHOPEDIC WIRE • Not recommended for stabilizing short oblique (45 degrees) or transverse fracture lines. • Contraindicated in dogs with fractureassessment scores in the moderate to low ranges. • Wiring techniques are used to supplement IM pins stabilizing short oblique or metaphyseal fractures in animals with very high fractureassessment scores.

ORTHOPEDIC WIRE • Equipment and Supplies • Cerclage wire is made from a malleable form of 316L • • • •

stainless steel. It may be purchased in a spool or as preformed loop wire and is available in sizes ranging from 22 gauge (0.64mm) to 18 gauge (1mm). Hemicerclage wire should be 18-gauge or 20-gauge monofilament 316L stainless steel. Twist knots may be formed by using pliers or old needle holders. Cerclage wire with a preformed loop at one end is secured with a specially designed wire tightener.

ORTHOPEDIC WIRE Application • Use only on anatomically reconstructed long oblique or spiral fractures. • Use 18-gauge wire for large dogs and 22-gauge or 20-gauge wire for cats and small dogs. • Place two to three cerclage wires per fracture line. Place wires perpendicular to the long axis of the bone. • Space wires one half to one bone diameter apart. • Support cerclage wires with an IM pin, interlocking nail, external fixator, or plate.

TENSION BANDS •

• • •

Indications and Biomechanical Principles : Tension is the predominant force when avulsion fractures occur at a point where groups of muscles originate or insert in bone. Contraction of the muscle group at these sites generates tension that pulls the bony insertion or origin from its anatomic location. The most effective way to resist tension is through application of a tension band. The purpose of a tension band is to convert distractive tensile forces into compressive forces.

TENSION BANDS Equipment and Supplies

• Equipment includes small Steinmann pins or Kirschner wires and orthopedic wire. • A high-speed wire driver is preferred for placing the Kirschner wires. • The orthopedic wire is secured with a wire tightener.

TENSION BANDS Application • Use two Kirschner wires or small Steinmann pins. • Place wires parallel to each other and perpendicular to the fracture. • Seat the wires in the opposite cortex. • Place the hole for the orthopedic wire the same distance below the fracture as the pins are inserted above the fracture. • Tighten the wire so it is in direct contact with the bone.

PLATE AND SCREW FIXATION • BONE PLATES AND SCREWS • Popular method for stabilization of fractures. • Modern plating technology - Swiss Arbeitsgemeinschaft fur Osteosynthesefragen (AO) – ASIF – AO VET. • Thorough understanding of the principles and techniques of application is essential.

PLATE AND SCREW FIXATION

PLATE AND SCREW FIXATION • Indications and Biomechanical Principles

• Bone plates and screws offer a versatile method of fracture stabilization and can stabilize any long bone fracture. • Bone plates and screws are particularly useful when postoperative comfort and early limb use are desired. • Bone plates and screws are used to treat animals with high, medium, and low fracture-assessment scores.

PLATE AND SCREW FIXATION • Screws used as lag screws cause compression at the fracture, increasing the friction between fragments and resisting the forces acting on the fracture. • Screws may be used to reconstruct articular fractures without plate support.

PLATE AND SCREW FIXATION • Screw holding power increases in a linear relationship with increasing diameter of the threads. • Bone plates achieve fixation of the fracture by friction generated by the application of a well contoured plate to the bone surface with screws. • Bone plates effectively resist the axial loading, bending, and torsional forces acting on fractured bones. • Periosteal perfusion & blood supply

PLATE AND SCREW FIXATION • Plates are susceptible to repeated bending stresses because of the plate’s eccentric location in relationship to the long axis of the bone. • Implant fatigue failure - Increasing the plate size, using a broad lengthening plate, or using a plate-pin combination.

PLATE AND SCREW FIXATION • Locking screw plate systems vs conventional plate systems. • Single unit. • Neutral position. • Construct yield strength. • The disadvantage is that screws must be placed perpendicular to the plate to lock. • Locking plates can be effectively used with indirect reduction and minimally invasive surgical techniques (MIPO).

Screws • Cortical and cancellous bone screws are made of 326L stainless steel or titanium. • A non-self-tapping screw requires that threads be cut into bone with a tap. • A self-tapping screw has a cutting tip to cut threads into bone and flutes to accept bone debris. • Cortical screws are fully threaded and designed for use in compact cortical bone. • The pitch(number of threads per inch) of the screw is greater than that of a cancellous screw.

Screws • Cancellous screws are either completely or partially threaded and are used primarily in the epiphysis or metaphysis. • The thread height(difference between the core diameter and outer screw diameter). • Cortical and cancellous screws are named for the outside diameter & are available in sizes ranging from 1.5 to 6.5mm. • Locking screws - threaded heads - threaded plate holes (locking compression plate).

Screws • Locking screws - large core diameter and shallow thread profile. • Locking screws may be self drilling and self tapping and may be used monocortically or bicortically. • Bone screws are used either to anchor bone plates to bone or to hold bone fragments in place. • Plate screws & Position screws. • Position screw can be inserted through a plate hole or placed in bone independent of the plate.

Screws • Cortical screws:

–Greater number of threads –Threads spaced closer together –Outer thread diameter to core diameter ratio is less –Better hold in cortical bone

(pitch is greater)

• Cancellous screws: – Larger thread to core diameter ratio

–Threads are spaced farther apart (pitch is smaller) – Lag effect with partially-threaded screws – Theoretically allows better fixation in cancellous bone

Figure from: Rockwood and Green’s, 5th ed.

Screws • Lag screws(also termed compression screws) are used to apply compression between fragments. • Whether a screw is used as a plate screw, a position screw, or a lag screw, appropriate instrumentation must be used to implant the screw correctly. • Specific drill guides are used for neutral and eccentric placement of plate screws and placement of screws independent of a bone plate. • Different sized drill bits. • Depth gauge & counter sink.

Application of Lag Screw • Reduce and secure the fracture before placing the lag screw. • For optimal compression, place the screw perpendicular to the fracture. • Drill the near cortex with a bit equal to the screw thread diameter. • Drill the far cortex with a bit equal to the screw core diameter.

• When using a partially threaded screw, be sure the threads do not cross the fracture.

Lag Screws • Functional Lag Screw note the near cortex has been drilled to the outer diameter = compression

• Position Screw - note the near cortex has not been drilled to the outer diameter = lack of compression & fx gap maintained

Lag Screws • Malposition of screw, or neglecting to countersink can lead to a loss of reduction • Ideally lag screw should pass perpendicular to fx

Figure from: OTA Resident Course - Olsen

Application of Position screw • Cortical screw or a fully threaded cancellous screw can function as a position screw. • A position screw is used to hold two bone fragments in anatomic alignment when compression would cause one fragment to collapse into the marrow cavity. • Hold the fragments in position with bone holding forceps and drill a thread hole through the cortex of each fragment with a drill bit corresponding to the inner core diameter (shaft) of the screw.

Application of Position screw • Use a depth gauge to determine the appropriate-length screw and cut threads in both cortices with the appropriate tap. • Insert the screw, using bone-holding forceps to hold the fragments in position and prevent distraction at the fracture line. • Gently tighten the screws (“finger tight”) until the screw head rests adjacent to the near cortex (or bone plate).

Application of Plate screw • Standard plate screws secure the plate to the bone by the force generated by the torque applied to the screw. • When inserting a plate screw in the diaphysis, drill a thread hole through the near (cis) and far (trans) cortices. • Use the neutral drill guide to place the screw in the center of the plate hole. • Use the load or eccentric drill guide with the arrow pointed toward the fracture line to place the screw eccentrically initially and cause compression at the fracture line when the screw is tightened.

Application of Plate screw • To insert a 3.5-mm plate screw, use a drill bit that corresponds to the inner core diameter (shaft) of the screw (2.5mm) and a tap that corresponds to the outer thread diameter of the screw (3.5mm). • Determine the length of screw needed with the depth gauge placed through the plate hole and cut threads into the near and far cortices with a tap. • Use a tap sleeve when cutting threads to maintain axial alignment relative to the thread hole and to prevent soft tissue from winding around the tap threads.

Application of Plate screw • Remove the tap, and flush the hole with sterile saline to eliminate bone debris and lubricate the hole. • Insert a cortical screw and use fingers only on the screwdriver to tighten it . • In spongy metaphyseal or epiphyseal bone, use a cancellous bone screw as a plate screw and place in a similar manner.

Application of Locking screw • Locking screws must be accurately inserted perpendicular to the plate hole for the threads to match and secure the screw. • Screw the threaded drill guide into the locking hole. Be sure the guide is secured. • Drill with the appropriately sized drill bit. Remove the drill guide, and measure the hole to determine screw length.

Application of Locking screw • Locking screws may be used as monocortical or bicortical screws. • If using a monocortical screw, take care that the screw does not contact the far cortex as this may interfere with securing the screw head. • Use the screwdriver to seat the screw or use a power driver with a torque limiting attachment to seat the screw.

Bone Plates • Bone plates are made of 316L stainless steel or titanium. • Bone plates are designated in several different ways, including plate length, screw size that the plate hole will accept, plate and screw hole configuration, and function. • Plate length is designated by the number of plate holes. • The 3.5 broad plates range in length from 4 to 22 holes, and the 2.7 plates range from 4 to 12 holes. • Plate size is determined by the cortical screw that the plate holes will accept.

Bone Plates • Plate hole configuration is also used to designate the type of plate. • A plate hole can be round (e.g., veterinary cuttable plate) or • Oblong (e.g., dynamic compression plate). • A bone plate with oblong holes is referred to as a dynamic compression plate(DCP) because compression can be applied to the bone through the dynamic action of the screw tightened. • The configuration of the oblong hole is based on a spherical gliding principle modeled after a ball rolling down an inclined plane.

Spherical gliding principle model

Bone Plates • Proper screw placement is ensured by using drill guides that center the drill hole in either a loading or neutral position. • In the loading position, approximately 1mm of compression is achieved for each screw tightened, whereas in the neutral position, approximately 0.1mm of compression is achieved. • The spherical gliding principle is implemented on both ends of each plate hole in the limited-contact dynamic plate(LC-DCP). • Locking plates have threaded that accept and lock with the locking head screw. • The locking compression plate(LCP) has a combination plate hole that can accept either standard screws or locking screws.

Bone Plates • Bone plate configuration is also used to designate the plate type. • The 3.5 and 4.5 bone plates are available as standard plates and broad plates. • The broad plates are wider, which gives them increased strength and stiffness. • LC-DCPs are manufactured so that there is limited contact between the plate and bone to minimize interruption of blood flow (undercutting the bottom surface of the plate between the screw holes).

Bone Plates • The undercutting also allows greater angulation (up to 40 degrees) of plate screws. • Specialized bone plates (e.g., reconstruction plates, angled plates, and condylar screw plates) are available for selected orthopedic conditions. • A 3.5 broad DCP may serve as a compression plate, neutralization plate, or buttress plate, depending on how it is applied to the bone. • A bone plate serves as a compression plate when compression is applied to the fracture line through proper application of the plate and screws.

Bone Plates • A DCP may only function as a compression plate if the fracture line is transverse or short oblique (no greater than 45 degrees). • If the fracture line is greater than 45 degrees or is comminuted, the plate cannot be used to compress the fracture lines. • A neutralization plate neutralizes physiologic forces acting on a section of bone that has been anatomically reconstructed and stabilized with screws and wire. • Indications for a neutralization plate include reducible comminuted fractures and oblique fractures in which the fracture line exceeds 45 degrees. • A bridging plate spans a fragmented section of bone and a buttress plate holds a collapsed epiphysis in position.

Bone Plates • The most common application of a bridging plate is with fragmented diaphyseal fractures in which surgical reduction and stabilization of the bone fragments are not technically feasible (i.e., nonreducible fractures). • The plate size (2, 2.7, 3.5, or 4.5) necessary varies depending on patient weight and bone dimensions. • ASIF and AO have developed charts that can be used to select a suitable plate relative to body weight. • The plate length should be sufficient to prevent premature loosening of plate screws and subsequent loosening of the plate from the bone surface.

Bone Plates • Plate should span the bone length for optimal performance in diaphyseal fractures. • The minimum length of plate should allow purchase of six cortices in the main bone fragment above the fracture and six cortices in the main fragment below the fracture - adequate distribution of stress among the plate screws. • Other plates useful in small animals include the reconstruction plate, veterinary cuttable plate, canine acetabular plate, and canine distal radial plate.

Bone Plates • Reconstruction plates have deep indentations in the sides of the plate between plate holes. • These plates may be contoured in three planes, making them especially useful for treating fractures of bones with complex threedimensional (3D) geometry, such as the pelvis, the distal humerus and femur, or the mandible. • Veterinary cuttable plates(VCPs) are available in two sizes, designated by the size of screw that the plate hole will accept.

Bone Plates • The 2/2.7 VCP can be used with either a 2-mm or 2.7-mm cortical screw, whereas the 1.5/2 VCP can be used with either a 2-mm or a 1.5-mm cortical screw. • The VCP is popular because it is available in varying lengths up to 50 screw holes (300mm). • The plate can be cut so that it has the desired number of holes. • VCPs are often used in a stacked configuration to bridge comminuted fractures in smaller patients.

Application of Compression plate • The compression plate is used to generate axial compression at the fracture. • Contour the plate properly relative to the bone surface (plate remains slightly offset (1 to 2mm) from the surface of the bone at the fracture line). • Secure the plate to the bone with plateholding forceps, ensuring that the ends of the plate lie over the bone.

Application of Compression plate • If the plate is contoured to conform accurately to the bone surface, the fracture line will load asymmetrically. • The net result is compression of the fracture line beneath the plate and widening of the fracture near the far cortex. • The gap in the far cortex is prevented through pre stressing the bone plate by over contouring it relative to the bone surface so the center of the plate is lifted 1 to 2mm above the bone surface.

Application of Compression plate • When the plate screws on each side of the fracture line are tightened, each main bone fragment is pulled up against the plate, compressing the far cortex. • Insert the two plate screws nearest the fracture (loaded position) and tighten them to achieve compression of the fracture line. • Insert subsequent plate screws in holes in an alternating manner on either side of the fracture, working toward the plate ends. • Adequate compression of the fracture is generally achieved with loading of the first two screws.

DCP as a compression plate

Application of Neutralization plate • First, reduce and stabilize the fracture with a series of lag screws, multiple cerclage wires, or a combination of both. • Use a bone plate to bridge the area and to neutralize forces that would act to collapse the fracture. • Apply a neutralization plate to the tension surface of the bone, but contour it to the anatomic surface of the bone.

Neutralization Plates • Neutralizes/protects lag screws from shear, bending, and torsional forces across fx • “Protection Plate"

Figure from: Schatzker J, Tile M: The Rationale of Operative Fracture Care. Springer-Verlag, 1987.

Application of Neutralization plate • Separation of the fracture line beneath the plate will not occur because the fracture lines have already been compressed with lag screws or cerclage wire. • The neutralization plate protects the reconstructed bone from all torsional, bending, and shearing forces. • The recommended number of cortices (six) engaged on each side of the fracture is the same as for a compression plate.

Application of Neutralization plate • With a neutralization plate, insert all screws in the neutral position, beginning from the ends of the plate and working toward the center. • If a plate screw cannot be inserted because it lies over a fracture line, leave the hole empty. • If the plate hole lies over a lag screw placed through the bone, leave the hole empty, or insert a screw that purchases only the near cortex.

Plate fixation metacarpal & femur

Application of Bridging plate • Precontour the plate to match the normal anatomic shape of the bone. • Use a radiograph of the intact bone of the opposite leg as a template (severely comminuted fracture). • Align the bone to restore length and correct rotational orientation before securing the plate. • The bridging plate serves as a splint to maintain the spatial alignment of the bone during healing.

Application of Bridging plate • The plate and screws will carry all the applied loads during the early postoperative period. • Purchase a minimum of eight cortices rather than six. • Use a stronger and stiffer plate because it also will be subject to substantial loads until bone is deposited within the fracture gap to form a bony column. • For optimal strength and stiffness, use a broad plate, lengthening plate, or stacked VCP rather than a standard plate. • Support the plate with ancillary implants (IM pins or external skeletal fixators) that share the applied loads during the early healing period.

Application of Bridging plate

Application of Bridging plate • With a plate–IM pin combination, insert an IM pin approximately 50% of the diameter of the marrow cavity, being careful to maintain the rotational alignment and axial length of the bone. • Contour a plate of appropriate length and apply it to the appropriate surface of the bone. • Insert the most proximal and distal plate screws so that they avoid the IM pin and engage both near and far cortices. • Insert the plate screws near the center of the plate so that they engage only the near cortex (monocortical screws)

Application of Buttress plate • Apply a buttress plate to shore up a metaphyseal fracture or protect a screw repair of an intraarticular slab fracture. • The buttress plate functions to prevent collapse of the adjacent articular surface. • To prevent any slipping of the plate and collapse of the articular surface, insert the screws in the juxtaarticular portion of the plate by first placing the drill guide adjacent to the part of the plate hole nearest the fracture. • Butting the screw head to that portion of the plate during the initial screw insertion prevents the plate from sliding.

Application of Locking plate • To use the locking plate as a bridging plate, select a plate long enough to span the bone. • Precontour the plate to match the normal anatomic shape of the bone. • Use a radiograph of the intact bone of the opposite leg as a template to help contour the plate. • If all locking screws are used, the plate does not have to conform completely to the bone.

Application of Locking plate • Align the bone to restore length and correct rotational orientation, and hold the plate in position with plate holding forceps. • The alignment must be correct before securing the plate, as the locking screws will hold the bone in that position. • Secure the plate to the bone with locking screws or a combination of standard and locking screws. • If using a combination of standard screws and locking screws, the plate should conform to the bone and the standard screws should be applied first to pull the bone to the plate.

Failure to Apply Concepts Classic example of inadequate fixation & stability • Narrow, weak plate that is too short • Insufficient cortices engaged with screws through plate • Gaps left at the fx site

Unavoidable result = Nonunion

Figure from: Schatzker J, Tile M: The Rationale of Operative Fracture Care. Springer-Verlag, 1987.

Summary • Respect soft tissues • Choose appropriate fixation method • Achieve length, alignment, and rotational control to permit motion as soon as possible • Understand the requirements and limitations of each method of internal fixation

References • Emmerson TD, Muir P: Bone plate removal in dogs and cats, Vet Comp Orthop Traumatol12:74, 1999. • Gautier E, Sommer C: Guidelines for the clinical application of the LCP, Injury 2003 34 (Suppl 2):B63, 2003. • Haaland PJ, Sjöström L, Devor M, Haug A: Appendicular fracture repair in dogs using the locking compression plate system: 47 cases, Vet Comp Orthop Traumatol 22(4):309, 2009. • Miller DL, Goswami T: A review of locking compression plate bio-mechanics and their advantages as internal fixators in fracture healing, Clin Biomech22(10):1049, 2007.

References • Reems MR, Beale BS, Hulse DA: Use of a plate-rod construct and principles of biological osteosynthesis for repair of diaphyseal fractures in dogs and cats: 47 cases (1994-2001), J Am Vet Med Assoc 223:330, 2003 • Roe SC: Evaluation of tension obtained by use of three knots for tying cerclage wires by surgeons of various abilities and experience, J Am Vet Med Assoc 220:334, 2002 • Theresa Welch Fossum: Small Animal Surgery Fourth Edition • Marvin L Ormstead: Small Animal Orthopedics

Definition  A method of fracture treatment ,that involves

the percutaneous placement of a series of transcortical pins or wires , which are externally connected to a rigid frame

Indications for use  Long bone fractures  Open fractures  Comminuted fractures that cannot be

anatomically reconstructed  Osteomyelitis  High-energy fractures with soft- tissue injuries

and vascular compromise

 Transarticular ESF in arthrodesis  Temporary splintage during healing of

soft tissue or osseous structures  Nonunion / with bone graft

 Corrective osteotomy for antebrachial

/tibial growth deformities  Limb lengthening procedures

Conjunction with internal fixation- in humeral, femoral or tibial fractures

 Hybrid ESF system- humeral, radial

or tibial fractures with very short distal or proximal fragment

 Mandibular or maxillary

fractures- usually with acrylic fixators  Lumbosacral fractures & luxations  Avian limb fractures

 Fracture repair in small exotic

mammals

Advantages of ESF  Minimally invasive method, preserving blood supply & soft

tissues  No implants at the fracture site  Possible closed application which limits iatrogenic trauma

 Provides immediate wt. bearing after surgery  Maintains normal joint mobility

•Provides optimum environment for osteosynthesis & wound healing •compatibility with internal fixation devices •Technical ease of application and removal

•wound management in open fractures •Reusability of the pin clamps & connecting bars

Disadvantages of ESF  Device must be cleaned and monitored regularly  Care to prevent additional damage to animal/device  Aftercare is more labor intensive  More rigid type II and III frames cannot be used for

fractures of femur & humerus

 Difficult to apply and more pain in areas of increased

muscle mass

 Extremely high cost

ESF FRAMES

LINEAR

HYBRID CIRCULAR

Equipment ESF

3 BASIC UNITS

FIXATION PINS

Inserted into bone To hold major Fragments

EXTERNAL CONNECTORS

Support fractured Bones

LINKAGE DEVICES

Attach fixation Pins & external Connectors

FIXATION PINS : classification



on basis of implantation method HALF PIN penetrate only one skin surface but both bone cortices

FULL PIN Penetrate one skin surface then both cortices ,and then the opposite Skin Surface

On basis of structural design  Smooth pin :

Rely on friction to remain stable in the bone  Threaded pins:  Positive profile and negative profile  Centrally threaded and end threaded

Positive & negative profile threaded pins  Pins in which core diameter of the threaded section is smaller than the diameter of the smooth section have negative thread profile  If the core diameter is consistent b/w smooth &

threaded regions ,thread profile is positive

Positive profile transfixation pins used in ESF

Centrally threaded & End threaded pins

 Centrally threaded pins are used as full

pins with type ÌÌ or ÌÌÌ external fixator frames  Central threads engage bone & smooth

pin ends extend beyond the skin surface  End threaded pins are described a/c to

no. of cortices engaged by threads (one cortex & two cortex end threaded pins) End treaded pin

Centrally threaded pin

External connectors  Made up of stainless steel, titanium alloy ,

carbon fibre, aluminium or acrylic  External fixator & linkage devices may be

fashioned from acrylic for ACRYLIC -PIN EXTERNAL FIXATOR (APEF)  APEF system contains +ve profile threaded fixation pins ,packaged acrylic & sterilized acrylic column molding tubes

SK double clamp

Linkage devices

Kirschner double clamp

Secur-U clamp Kirschner single clamp

S K single clamp

Kirschner type linkage devices for joining fixation Pins to external connecting bars & external connecting bars to each other.Note the larger holes for the external connecting bars & smaller holes in the bolts for Fixation pins

Linear ESF Configurations  Type I ,II or III configuration  TYPE I Configuration  Utilize half pin splintage fixation pins  Connecting frame placed on only one side of the limb  Unilateral constructs  Classified as *type Іa (unilateral and uniplanar) *type Іb (unilateral and biplanar)

Type Ia (unilateral–uniplanar) fixators  All the fixation pins & connecting frame

occupy a single plane (uniplanar)  Usually applied to cranial medial surface

of radius/ tibia and lateral surface of femur/ humerus  Fixation pins are half pins

Type Ib (unilateral-biplanar) fixators  Applied most often to radius &

tibia

 For radius & tibia–one ext. bar is

placed on craniomedial surface & 2nd bar on craniolateral surface

Type II (bilateral-uniplanar) fixators  Utilize full pin splintage fixation pins  Cannot be placed on femur/ humerus

because of adjacent body wall  Applied only to radius/tibia in

Maximal type ІІa

mediolateral plane  Maximal type ІІa & minimal type ІІb

Minimal type ІІb

Type III(Bilateral-biplanar) fixator  Combination of type І and type ІІ  Type І and type ІІ systems placed

approx. 90° to each other  Can’t be applied to femur or humerus  Indicated in very large dogs

TIE-IN CONFIGURATION  Combination of ESF (type Іa or Іb) with intramedullary pin

 Increases rigidity of fracture fixation in humerus & femur as type ІІ &Type ІІІ frames cannot be

applied

 No. of fixation pins is limited to 2 or 3 pins above

& below the fracture

Tie – in configuration

Biomechanics  Fixator rigidity depends on:

 Type of configurationType ІІІ > type ІІ > type І biplanar type Іb more resistant to cranial/caudal shear forces compared with type ІІ.  Number of used pins: at least 2 & up to 4 pins/bone

segment

 Diameter and design of the pins – the diameter ≤ 25 % of the bone’s diameter

 by widening pin spacing within pin groups & by the

distance between pin groups

 The most central pin should be 1-2 cm away from the

fracture line

 Moving the connecting bar closer to the bone makes

the pins more resistant to bending

 Using a “tie-in” configuration increase significant in

bending strength

Fixation pin application  Preoperative planning

 Patient fracture assessment  Most important principle -asceptic surgery  Injured limb suspended from hook in the ceiling  Patient Draping

 choose a surgical approach  Delimitation of safe corridors

for insertion of pins

 Most proximal and distal pins inserted after a stab skin 



   

incision Pre drilling a pilot hole with slightly smaller diameter drill bit Transfixating pins inserted by using low-speed power drill Fracture reduced & connecting bar connected to proximal and distal pins by clamps Clamps placed 1-2 cm away from the skin surface Central pins are inserted above and below the fracture Rest of needed pins inserted & bolts tightened

Postoperative management  Postoperative analgesia  Pin-skin interface cleaned with antiseptic 

  

solution Incision around pins released/extended in case of skin tension Sterile gauze sponges placed around & between fixation pins Limb wrapped with vetrap (bandage material ) Activity restricted to least walking & physical rehabilitation

Circular External Skeletal Fixators

(Ilizarov technique)  Most recent innovation in ESF

technique in dogs and cats & also in large animals.  Developed by the Russian

physician Gavriil A. Ilizarov  CESF consist of a series of

complete and/or incomplete external rings that are interconnected by a series of threaded rods

 These are modular systems which

can be assembled in numerous configurations to  stabilize fractures and arthrodeses,  perform bone lengthening and transport  correct angular, translational and rotational

deformities  Each ring is secured in position along the rod by

placing a nut on either side of the ring

 Elongation of the frame allows for distraction osteogenesis in

which regenerate bone is produced within the gap created when an osteotomy is distracted slowly and sequentially  “Discontinuity of a skeletal segment necessarily triggers the

repair process which will continue as long as integrity of both osteogenic tissue & its vascular supply is maintained”  Traditional CFs use small diameter wires, rather than pins, as

fixation elements

Standard circular fixator frame for fracture management

Equipment  Wires  Rings

 Wire fixation bolts  Threaded rods  Nuts  Wire tensioner & wrenches

Wires :  1.0,1.2 or1.5mm diameter used in cats/ dogs

 Olive wires- wires with a bead positioned midway along the wire  Provide interfragmentary compression & increase stability of frame construct  more the no. of fixation wires- more stability of fixation  Wire angles < 45°should be avoided

Olive wires

Rings  Partial ring & full ring  Five–eighth/stretch ring are used when rings would limit joint motion (elbow/stifle)  Partial rings -versatile  Full rings -more available holes for rods & wire, not versatile  ring diameter , axial stiffness, torsional &

bending stiffness  Smallest ring allowing ≥2 cm distance b/w skin & inner circumference of ring selected

Wire fixation bolts  Cannulated wire fixation bolts –allow wire passage

via a concentrically placed hole at base of bolt head  Slotted wire fixation bolts have an eccentric slot located under the bolt head & parallel to its long axis  Wire must be fixed without deformation

Frame construction  Threaded rods used to connect rings & form frame  Telescopic rods- hollow rods used as supports &

connecting elements of ring

 Frames are constructed so that one ring & its wires

are placed at proximal end and another ring & its wires are placed at distal end of long bone

 2 additional rings placed so that their wires

penetrate proximal & distal bone segments close to the fracture

Wire tensioner

Hybrid External Fixator  Combination of a ring & a linear

fixator  Indicated for fractures with juxtaarticular bone segments  May be applied to radius,tibia,femur & humerus  Can also be used to stabilize corrective osteotomies for angular limb deformities

Larger transfixation wires can be combined with the use of rings & wires in a Hybrid frame

Clinical Applications of ESF  Fracture fixation  Radial & tibial  Humeral & femoral

 Mandibular & maxillary  Stabilization of spinal fractures & luxations  Arthrodesis  Bone lengthening  Bone transport for bone defects  Angular limb deformity correction

Fixation of spinal fractures & luxations  Spinal arch external fixator

components developed for spinal stabilization  Fluoroscopically guided

percutaneous pin placement can be performed when applying external skeletal spinal fixation

Bone transport (limb salvage)  Method by which one or two segments of normal

bone adjacent to a defect are slowly transported into the defect while new bone forms in the distraction pathway  Used in dogs with radial/tibial neoplasia or severe osteomyelitis with bone loss  A segment of bone is created with a corticotomy made 2-3 cm from one end of one of the main fragment

Acrylic external fixation  Acrylics are commonly used for the repair of fractures  The acrylic column acts as both the connecting

rod and transfixation pin-gripping device  Dental acrylic or hoof repair acrylic are suitable  It can be moulded over pins after curing to a dough stage  Acrylic ESF offers the advantage of reduced

cost , improved versatility & simplified application technique when compared with kirschner ESF

Advantages of acrylic system  Ability to contour the connecting bar to match any fracture

configuration  Fixation pins of any diameter may be used  Fixation pins do not have to be in the same longitudinal

plane  Light in weight encouraging earlier return to function

 Placing the positive profile threaded pin without the difficulties of

passing them through clamps  Inexpensive system

Uses of acrylic fixators  Fixation of mandibular & maxillary fractures  Fixation of long bone fractures  Primary fixation device or intra-oral

splint for mandibular & maxillary frcatures

Complications of ESF          

Pin tract infection Focal osteomyelitis Ring sequestrum Premature pin loosening Instability at the fracture site Pin breaking Pin tract osteolysis Pressure necrosis of skin Iatrogenic bone fracture soft tissue impalement

External co-aptation Techniques

Application of a Robert Jones bandage. A. Placement of stirrups on medial and lateral aspects of paw. B. Wrapping with rolled cotton starting at distal end. C. Cotton padding in place. D. Application of stretch gauze, compressing cotton. E. Application of elastic tape or self-adherent stretch tape after stirrups are folded up, leaving only digits 3 and 4 exposed.

• The materials necessary to apply a Robert Jones bandage include one to three 1 -lb rolls of absorbent cotton, 1- or 2-inch white adhesive tape, several rolls of 3- or 4-inch stretch gauze, one to three rolls of 3- or 4-inch elastic tape or self-adherent stretch tape, and a nonadherent dressing when indicated. • Application is begun by placing adhesive tape stirrups medially and laterally from the carpal or tarsal area distally

• Placement of a nonadherent dressing on any open wound or surgical incision is done at this time. • The next portion of the bandage is the application of the cotton. One begins distally and wraps proximally, high into the axillary or inguinal regions. The ends of digits 3 and 4 should be left exposed, and the cotton should be wrapped with enough tension to make the bandage tight, but not tense enough to cause the cotton to tear. The final bandage should convert an irregularly shaped leg into a uniform-diameter or stovepipe configuration, thereby allowing the bandage to apply even pressure over the entire length of the leg

• After application of the cotton, even pressure is accomplished by wrapping from distal to proximal with 3- or 4-inch stretch gauze. • Each wrap should overlap the previous by about 50% its width, avoiding any formation of ridges and valleys, indications of uneven pressure. When wrapping the stretch gauze, one should apply enough tension to compress or reduce the size of the bandage adequately. • In most cases, the final diameter of the bandage after the stretch gauze is applied is 40 to 50% of the original diameter.

• To complete the bandage, the tape stirrups are separated and are placed along the appropriate medial and lateral sides. • Using either elastic tape or self-adherent stretch tape, the final layer is started, again distally, wrapping proximally and continuing to overlap each layer by 50% while taking care to maintain even compression. • When this layer is completed, only the distal ends of digits 3 and 4 should be exposed. • If the toes are not visible, adequate amounts of the surrounding cotton should be removed to allow exposure of the digits.

• The goal of the Robert Jones bandage is to provide immobili-zation while maintaining even compression over the length of the limb. • Compression can be evaluated by tapping over the length of the bandage; a properly applied bandage sounds like a ripe watermelon when it is thumped. • To obtain even compression may require several applications of the stretch gauze, beginning each wrap distally and continuing proximally to either the axillary or inguinal region.

• In smaller dogs and cats, cotton cast padding may be substituted for the roll cotton, thereby achieving a more uniform fit to the leg. • A more uniform fit may also be accomplished by removing the paper insert in the cotton roll, tearing the roll in half, and wrapping with 6-inch widths rather than 12-inch widths of cotton strips. • All layers of the bandage are wrapped in a lateral-to-medial rotation to allow for a neutral to slightly internally rotated position of the limb.

• Postbandaging care should include keeping the bandage clean and dry and observing the exposed digits for swelling or coolness to the touch. • If problems are noted, the bandage may have been improperly applied and should be removed and the leg reevaluated. • If no signs of problems are evident, the Robert Jones bandage may be left in place for up to 3 weeks.

Splinting Techniques

• External fixation by coaptation implies the use of casts, splints, or bandages to provide immobilization of an injured limb. These devices approximate the shape of the limb to which they are applied, and they provide stable fixation of bone fragments without the need for surgical implants at the fracture site.

• External fixation for orthopedic injuries in veterinary medicine offers distinct advantages over open reduction and internal fixation. In most instances, tissue and vascular trauma is reduced, the risk of infection is decreased, and the cost of application can be much lower than that of surgery.1 Careful case selection is required to achieve successful treatment of fractures with external coaptation. In general, these devices are best used in young patients (less than 1 year of age) that tend to heal rapidly with transverse or incomplete fractures distal to the elbow or stifle. External coaptation best neutralizes bending forces on fractures away from joints, rather than near joints, and requires stabilization of the joint above and the joint below the fracture..

• Therefore, coaptation does have disadvantages resulting from long-term limb immobilization that can cause severe disuse atrophy and possible “fracture disease.” The use of a below-the-knee cast bracing (Sarmientotype) system has been advocated; if properly used for certain tibial fractures, this type of system may reduce problems associated with total immobilization of the hind limb. • If a coaptation device is incorrectly applied, loosens, or becomes wet, skin necrosis and even gangrene can result. • Certain cases of multiple or severely comminuted fractures are best managed by internal fixation techniques, because precise anatomic reduction and adequate neutralization of forces acting on the fractures cannot be achieved with external coaptation

Indications • Coaptation splints are commonly used for immobilization of simple transverse fractures of the radius, ulna, fibula, metacarpals, metatarsals, and phalanges. • They can also be useful for immobilization of certain joints, such as the stifle, after traumatic injuries or surgical stabilization. • With most fractures, however, use of both internal fixation and external coaptation combines the disadvantages of both and, in general, should be avoided whenever possible. • Temporary coaptation devices usually are indicated in the acutely traumatized animal for prevention of edema, relief of pain, reduction of subsequent damage to soft tissue, wound protection from further contamination, prevention of development of closed fractures into open fractures, and fracture stabilization. Robert Jones bandages, coaptation splints of various materials

• Schroeder-Thomas splints, tape hobbles, Ehmer slings, Velpeau slings, and nonweightbearing slings have been described for temporary immobilization as well as for definitive immobilization of certain orthopedic injuries.

• The choice of coaptation device depends on each individual case and circumstance. • The coaptation device may serve as a temporary splint for traumatic injuries while waiting for definitive internal fixation, as a primary treatment of certain fractures, or as an adjunct to internal fixation or ligament repair. • Cost is another important aspect that must be considered as well as the availability of materials required for different coaptation devices

General Application Guidelines • A few general guidelines are relevant to application of all types of coaptation splints and casts. • Depending on the animal’s physical condition and the severity of the orthopedic problem, application of coaptation splints or casts is best performed with the patient sedated or under general anesthesia. • When the patient’s physical status precludes the use of chemical restraint, traction and excessive manipulation of the limb must be kept to a minimum.

Use of Stirrups • Application of adhesive tape on the cranial and caudal surfaces of the foot to form “stirrups” is usually necessary so the limb can be attached to the splint or cast securely. • In some instances, one should fix the strips of adhesive tape medially and laterally on the limb; this has been recommended for application of a full-encircling cast. • When lateral and medial stirrups are used, they must be incorporated into the lateral and medial sides of the cast, respectively, to avoid excessive pressure and possible skin necrosis over the outer distal metatarsal or metacarpal epiphyseal areas. • Encircling bands of tape should never be used on an animal’s foot because they can cause irreparable vascular damage and skin necrosis.

• If problems are encountered in attaching the tape to the foot, the skin can be dried with alcohol to increase the holding capacity on the foot. • Some veterinarians spiral a piece of adhesive tape around the cranial and caudal tape pieces to increase fixation of stirrups to the skin. • Two to three overlapping layers of elastic gauze applied snugly and evenly over the stirrups has also been used without problems to prevent the tape stirrups from slipping . • Good judgment must be used during application of these gauze layers to prevent vascular compromise. Tape application over the carpal pad can cause mild irritation to this structure at the time of tape removal, but it is usually not severe.

A. Application of adhesive tape stirrups on the cranial and caudal surfaces of the foot. B. Application of elastic gauze over the adhesive tape stirrups followed by overlapping layers of cast padding.

• A technique described specifically for cats uses longitudinal “anchor” strips of adhesive tape applied medially and laterally on the leg, with the tape ends extending proximal and distal to the bandage or splint. The exposed ends of the tape anchor strips are reflected back on the bandage and then are covered with a second layer of bandaging material, which locks the anchor strips on the bandage.

Use of Padding • The padding layer of the bandage provides protection, absor-bency, and minimal support to the limb, depending on the thickness of the padding layer. • The use of padding before cast or splint application may ensure patient comfort, but when used inappropriately or in excess, it may actually decrease a device’s ability to provide adequate immobilization. • Excessive padding, hair, and soft tissue structures increase the distance between the rigid part of the coaptation device and the rigid part of the limb (bone), and this can decrease the stiffness and effectiveness of the cast or splint. • Therefore, long hair should be clipped, but not shaved, before bandage placement, and adequate cast padding should be applied to provide comfort and to prevent skin irritation. • If properly applied cast padding actually enhances fracture fixation by compensating for slight tissue shrinkage after cast application

Limb Positioning • During application of any coaptation–in particular plaster, fiber-glass, and thermolabile plastic casts–for immobilization of a front or rear leg, the limb should be placed in a functional position while the material is still moldable. • The rear leg should be kept in a normal position with the hock slightly flexed. • When the casting material is conformed to the shape of the front leg, the carpus should be placed in slight flexion (15°) and deviated medially by 15° . • This positioning helps to prevent a valgus deformity, which otherwise could occur during manipulation because of the normal laxity of the radial carpal joint or as a result of eccentric growth of the radius and ulna in the immature patient. • External rotation of the metacarpus should be avoided, and the foot should be kept in a neutral position.

Proper positioning of the front leg for application of a fully encircling cast. The carpus is flexed slightly and is deviated medially

Coaptation Splints • Coaptation splints consisting of various rigid materials are used to approximate the shape of the limb to which they may be applied. • In general, they should not be used for immobilization of the humerus or femur. • Pre-made commercial splints consisting of plastic or aluminum are known as Mason metasplints or spoon splints. They are applied over padding on the caudal aspect of the limb. Because the limb is curved and the splint is straight, adequate padding is necessary to avoid soft tissue problems, but it may result in poor immobilization. • Molded splints of plaster, water-activated fiberglass, or thermolabile plastic can be fitted to the limb almost perfectly. For this reason, they seem to be tolerated better by the patient and cause fewer soft tissue problems during longterm use than Mason metasplints.

• Metasplints for the front or rear leg are primarily indicated for fractures of the distal radius and ulna, fracture-dislocations of the carpus or tarsus, and fractures of the metacarpal or metatarsal bones or phalanges. Stabilization of proximal radial or ulnar fractures usually is not adequate with these devices. Generally, the elbow joint cannot easily be immobilized without using a spica configuration over the shoulder.

Application Technique • Adhesive tape stirrups are applied on the cranial and caudal aspects of the paw, with the cranial tape extending beyond the paw 2 to 3 inches farther than the caudal tape. • The tape ends are then pressed together. A piece of precut cotton is applied to the back of the paw and antebrachium, or the leg is wrapped with at least two layers of cast padding, even if the splint is foam padded. • The splint is snugly secured to the limb with elastic gauze by wrapping the leg with firm conforming pressure beginning at the toes and extending proximally up the limb. • The stirrups are reflected up the caudal aspect of the splint and are secured with tape or another layer of elastic gauze. • The “gauze-covered” splint is covered with adhesive tape, elastic tape or conforming elasticized tape. • If the splint extends only to the elbow joint, a V-shaped section can be cut from the cranial aspect of the bandage material just below the joint to prevent pressure necrosis in that area .

• Application of aforeleg Mason metasplint. • A. Stirrups are reflected proximally and are secured to caudal aspect of metasplint. • B. Metasplint is secured to the limb with overlapping layers of elastic gauze followed by application of adhesive or elastic tape. • C. A V-shaped section is cut from the cranial aspect of bandage material at the elbow joint to prevent pressure necrosis.

A. and B. Application of a foreleg Mason metasplint without the use of adhesive tape stirrups

• Some clinicians apply metasplints by an alternative method that does not involve use of tape stirrups, slippage of the splint is prevented by wrapping tape proximally around the elbow to prevent flexion . The toes are left exposed, so circulation can be assessed.

Molded Lateral Splints

• Indications • A molded splint applied laterally on either the forelimb or the rear leg can provide immobilization of the elbow joint or stifle, respectively. It can also stabilize less severe fractures of the radius, ulna, tibia, and fibula. This type of coaptation can be particularly helpful in providing protection from bending forces after internal fixation or joint stabilization. The casting material can be extended over the shoulder or hip as a modified spica to provide partial joint immobilization.

Application Technique • Adhesive tape stirrups may not be necessary for application of this type of splint, especially if it extends proximally to include the shoulder or hip. The patient is placed in lateral recumbency with the injured limb positioned uppermost. The limb is padded with two layers of cast padding beginning at the toes and ending at the axilla or inguinal area.

• If the shoulder or hip is to be immobilized through the use of a modified spica splint, the layers of padding should encircle the chest wall or pelvis, respectively. • For splint application on the front leg, the padding creates a figure-of-eight pattern around the thorax and the affected limb, but the padding and the next layer of conforming gauze are carried behind the opposite axilla. Application of a molded foreleg lateral splint. A. Cast pad-ding encircles the affected limb and thorax. B. Molded conformable material is secured to limb with elastic gauze and elastic tape

• For a hip spica, the cast padding and conforming gauze applied to the affected leg and the opposite limb create a figure-of-eight pattern and can incorporate the proximal half of the opposite leg. When this configuration is used, the resulting coaptation device is called a “one-and-a-half leg” spica. • Care must be taken when applying a hip spica on a male dog so the prepuce is not included in the bandage. Spica splints are also restrictive, and some animals may not be able to stand without assistance

• Cast materials that can be molded to form a lateral splint are plaster, water-activated fiberglass, thermola-bile plastic or yucca board. Rolls of plaster, water-activated fiberglass materials, or thermolabile plastic can be cut to proper length or shape before application on the lateral aspect of the limb after activation. • Elastic gauze is used to conform the softened splint material to the limb and to attach the splint to the shoulder and chest wall or the hip and thigh area. The gauze-covered splint is then bandaged with elastic tape applied in a pattern similar to that of the gauze

Application of a molded lateral splint to the rear leg.

Schroeder-Thomas Splints • When correctly applied, this splint can be an excellent means for immobilizing joints postoperatively surgery and for immobilizing certain fractures. • This traction device can provide accurate and continued fixation of bone fragments by counteracting muscle forces and immobilizing parts of the skeleton. • Under certain circumstances, skeletal traction can be provided when transfixation pins located in the areas of the femoral or humeral condyles are incorporated into the splint so traction from the splint on the distal end of the affected limb controls the distal fracture fragment.

Indications and Possible Complications • The use of Schroeder-Thomas splints may be indicated for some fractures of the radius, ulna, and tibia; avulsion fractures of the tibial tuberosity and distal malleolar fractures are exceptions. • These splints have been used for fractures of the distal humerus (distal one-third), although not for condylar fractures, which require precise reduction of the joint surface to avoid degenerative joint disease. • Nonarticular fractures of the distal femur (distal one-third) are considered by some clinicians to be amenable to reduction and immobilization with a Schroeder Thomas splint, although supracondylar or condylar fractures must receive superb postreduction care because immobilization can be difficult to maintain. The splint has been used for temporary immobilization of the stifle and elbow joints postsurgically

• Application to a fracture of the proximal humerus or femur is definitely contraindicated because the ring of the splint must support and rest on the proximal fracture fragment • If the splint is used for proximal femoral and humeral fractures, the ring rests in the fracture site and acts as a fulcrum point, whereas the limb serves as the lever resulting in movement at the fracture site. • In these circumstances, fracture disease (nonunion, quadriceps tiedown, joint stiffness) results. The splint often loosens with time because of the dynamic nature of its application. • Circulatory problems causing tissue necrosis can develop as a result of loosening, swelling of the limb, or improper application. Pressure necrosis under the ring of the splint, edema of the scrotum, severe limb edema, and strangulation of the foot can occur.

Configurations of a foreleg and hind leg Schroeder-Thomas splint and traction application for radioulnar fractures A. and tibial fractures B

Application Technique • Schroeder-Thomas splints should be custom-made for every individual case. Obviously, splint rods can be reused if they are the appropriate length for an individual patient. Because this type of splint is a dynamic traction device, it requires careful attention by the owner and periodic adjustment by the clinician. • A Schroeder-Thomas splint is constructed of aluminum rods (1/8-, 3/16-, or 3/8-inch diameter) available in 6-foot lengths or 12-foot coils. • For small dogs or cats, regular coat-hanger wire has been used. An average-size dog (30 to 40 lb) requires the 3/8-inch diameter aluminum rod. • Adhesive tape and combine roll or elastic gauze are used for application of the stirrups and the traction slings, respectively. • A vise is helpful in shaping the rod, and bolt cutters or a hacksaw are necessary for cutting the rod. The shape of the splint is modified in relation to the specific leg injured, the bone that is fractured, or the joint that is involved. • Traction application also varies according to the fracture, so the fragments can be separated and aligned

• The first step in construction of a Schroeder-Thomas splint is the formation of the upper ring at the proximal end of the splint. • For the rear leg, the diameter of the ring is determined by measuring the distance between the cranial aspect of the wing of the ilium and the caudal point of the ischium; • for the foreleg, the ring diameter can be determined by measuring the length of the scapular spine. • The bottom of the ring should be flattened to conform to the animal’s axillary area or thigh. • The bottom of the ring must bend medial to the vertical bars at a 45° angle at the middle of the ring. The ring can be bent, or the vertical bars can be bent to accommodate this angle. • The lower half of the ring should be padded; however, excessive padding may cause irritation and circulatory problems and should be avoided. • Applying tape to the ring with the adhesive side facing outward and then wrapping the lower half of the ring with thin strips of cotton or cast padding work well. The tape with the adhesive side inward is applied over the cotton loosely so the padding is soft and conforms to the inguinal or axillary region

• The vertical bars of the splint are sometimes left straight to accommodate certain fractures. However, each case should be considered on an individual basis and the splint configuration varied accordingly. • For the rear leg, the front bar is bent to conform to the normal angulation of the stifle and hock; the rear bar is left straight. The angles of the front bar are varied according to the injury . • For the fore-limb, both bars are bent to conform to the angulation of the elbow. Although various configurations for humeral and radioulnar fractures has been used successfully and seems to be well tolerated by most animals.

• The vertical bars are bent and connected with adhesive tape at the bottom of the splint. The length of the splint is determined by gently extending the limb so the end of the splint coincides with the end of the toes. • The limb should not be stretched taut in a SchroederThomas splint. The middle of the horizontal bar formed by connecting the vertical bars can be bent into an inverse-V shape so the adhesive tape stirrups fastened there will not be worn away by walking. • A separate piece of aluminum rod can also be added to the bottom of the splint to protect the tape. The width of the distal end of the splint should be approximately three times the width of the paw.

• The finished splint should be completely wrapped as smoothly as possible with adhesive tape for cosmetic purposes. More important, this procedure prevents slippage of traction slings. The completed splint is applied to the leg carefully, with the ring snugly placed in the axillary or inguinal area. The splint is secured initially to the distal end of the foot by means of an adhesive tape stirrup. • For additional support, a spiral of tape (“barber pole”) can be applied over the foot to help secure the vertical stirrups. • Wrapping tape circumferentially around the foot usually causes swelling and should be avoided. Cotton can be used to pad between the toes. The adhesive tape stirrups should not be used to apply traction.

• Traction is applied by means of the combine roll or wide elastic gauze used to secure the leg to the vertical bars of the splint. • Both products, but especially the elastic gauze, must be used with caution, because the application of excessive tension can cause necrosis or edema. • Positioning of the traction slings depends on the nature of the fracture. For fractures of the tibia, the traction slings are placed around the hock joint first and then in the femoral area to provide traction on the tibia. • For distal femoral fractures, the first traction sling is applied around the hock joint, and then one is applied around the proximal tibia to provide traction on the femur. Traction slings should be applied in such a manner that they provide adequate medial support to both the tibia and femur and avoid a valgus deformity of the limb. • For fractures of the front leg, a traction sling is first applied at the level of the elbow, pulling the humerus caudally. The second sling is applied at the level of the carpus, pulling it cranially, which increases the traction on the radius, ulna, or humerus. • As a tension can be applied caudally on the radius and ulna; a support sling placed in the area of the distal humerus maintains even pressure on the limb and reduces motion.

• The entire Schroeder-Thomas splint can be covered with orthopedic stockinette to protect the device.

Post application Care • Excellent client and professional care is essential in maintaining a Schroeder-Thomas splint after application. The limb must be kept dry and clean, and the animal must be confined. • Scheduled rechecks should be performed on a weekly basis, and clients must be diligent in evaluating the device for loosening, irritation, or swelling of the limb. If mild edema does occur, the animal must be monitored carefully for the next 24 to 48 hours; the splint may have to be adjusted or removed if this swelling persists or becomes more severe. • Clients must be informed that reevaluation of the device whenever one suspects a problem is essential for proper splint management.

Due to its high metabolic rate bone is in a state of continous remodelling with simultaneous osteoblastic bone formation and osteoclastic resorption No scar tissue formation in bone healing

Bony union OCCUR BY TWO DIFFERENT REPAIR MECHANISMS Direct healing or primary bone healing Indirect healing or classical bone healing

IT DEPENDS ON Effectiveness of implant in providing stability Biological environment in fracture site

INDIRECT BONE HEALING Occurs when osseous tissue is formed through transformation of fibrous tissue or cartilage Occurs in fractures in which some movement is possible between fractures due to lack of rigid fixation

STAGES IN INDIRECT HEALING INFLAMMATION PHASE Fracture Formation of haematoma

REPAIR PHASE Replacement of granulation tissue by callus Replacement of callus by lamellar bone REMODELLING PHASE Remodelling of bone to normal contour.

HAEMATOMA HAEMATOMA -Does not provide much mechanical support -Scaffold for cells -Release growth factors stimulating angiogenesis and bone formation.

Fractured bone Damaged soft tissues Hematoma formation and activation of coagulation cascade

Influx of inflammatory cells Production of interleukins and prostraglandins Platelets source of growth factors Mitosis and differentiation of mesenchymal cells Angiogenesis

•Fibrin within the clot- first supportive tissue at fracture site •After invading clot- mesenchymal cells differentiate into fibroblasts, chondroblasts or osteoblasts •Callus formed•External: from periosteum •Internal: from endosteum •Bridging callus 2 weeks after injury •Made of woven bone Compaction and remodelling

REPAIR PHASE Organisation of the haematoma Transformed into granulation tissue Granulation tissue matures into connective tissue Migration of osteoprogenital cells to the fracture site.(chaemotaxis proliferation and differentiation facilitated by TGF and BMP)

TRANSFORMATION INTO HARD CALLUS Mineralisation of undifferentiated callus. Mesenchymal cells transformed into chondrolast fibroblast or osteoblast. Fibroblast by membraneous ossification replaced by bony callus. Chondroblast by enchondral ossification replaced by bony callus.

REMODELLING PHASE Morphological adaptation of the bone to regain optimum strength. Woven bone replaced by cortical bone and medullary cavity is restored

DIRECT HEALING/PRIMARY BONE HEALING If fracture reduction is accurate and stability is rigid then healing occurs without external callus formation Ends perfectly apposed and compressed firmly Gap must be very small- 150 to 300μm

Classified into:

1. CONTACT HEALING 2. GAP HEALING

CONTACT HEALING Occurs in areas of cortical bone contact Osteonal remodelling across the fracture plane Formation of cutting cones

GAP HEALING Occurs in small fragment gaps between contact zones. Gap between fragments greater than 0.02mm but less than 0.08mm. Gap gets filled with lamellar bone oriented perpendicular to long axis Remains a weak site until integrated to normal bone architecture by remodeling

Advantage of primary healing over classical healing Because the fragments are extremely stable, bone as a whole is able to be loaded Allows early return to limb function during healing

Disadvantage of primary healing over classical healing Because the process of remodeling takes a long time, the implants used cannot be removed in the near future Slower than classical healing Bone union tends to be weaker in early stages

Bridging osteosynthesis Involves stabilization of 2 ends of fracture without the anatomical reduction of each fragment Site is left as undisturbed as possible Healing by callus formation but in an environment of stability

Biological healing should not be disturbed unless a mechanical advantage can be gained More rapid return of bone strength whilst allowing limb function during healing

Distraction osteogenesis Results from gradual distraction of bone segments often after osteotomy Concept used in ESF for limb lengthening and treatment of angular deformities

Gradual widening of gap, 1mm per day allows deposition of parallel columns of osteoid leading to formation of lamellar bone In case of instability- formation of intermediate cartilaginous phase/ fibrous tissue

Goal of distraction osteogenesis Lengthen a bone that is too short as a result of premature growth cessation, loss of a segment of the bone or overriding mal union caused by previous trauma

Physeal fracture healing Physis is weaker Fracture heals rapidly by continued growth of physeal cartilage and metaphyseal cartilage formation as the growing cells and vasculature is undamaged Endochondral ossification

Trabecular bone fracture healing Does not heal by periosteal callus formation unless there is significant instability Increased osteoblastic activity on either side of fracture when immobilized New bone deposited on existing trabeculae and gaps filled with woven bone

Factors affecting bone healing Age Weight Quality of reduction Stability of site Type of fracture

Extent of blood supply Bone involved Presence of infection Systemic disease drugs

Promoting fracture healing Bone grafts Electrical fields Low intensity pulsed ultrasound Demineralized bone matrix Growth factors Autologous bone marrow Gene therapy

RADIOGRAPHIC EVALUATION DIRECT HEALING Disappearance of fracture line gradually. No formation of external callus. INDIRECT HEALING Loss of radio opacity. Fracture becomes less defined and sharp. Callus seen when mineralization occurs.

Radiographic signs of indirect bone healing 5 to 10 days post reduction- fragments lose sharp margins 10 to 20 days- callus formation, decreasing gap size ≥30 days- fracture line gradually disappears, increased opacity of callus ≥3 months- cortical shadow visible through callus

HEALING WITH DIFFERENT IMPLANTS EXTERNAL COOPTATION-bridging callus formation. ESF-less rigid fixator-indirect union. rigid fixator –Direct healing. COMPRESSION DEVICES- increase fracture stability. Direct union.

DELAYED UNION Delayed union is the prolongation of time to fracture union No definite timetable to define delayed union exists Delayed union is due to Inadequate blood supply Infection Incorrect splintage

NON UNION Ununited fracture in which the repair process has stopped. Non-union has many causes including: Bone or soft tissue loss Soft tissue interposition Poor blood supply Infection Pathological fracture Poor splintage or fixation Fracture distraction

COMPLICATIONS OF FRACTURE HEALING DEPT OF SURGERY AND RADIOLOGY.

COMPLICATIONS OF FRACTURE HEALING INCLUDE 1. 2. 3. 4. 5. 6.

FRACTURE DISEASE NON UNION DELAYED UNION MALUNION INJURY TO BLOOD VESSELS INJURY TO NERVES

• 1 FRACTURE DISEASE: is “the irreversible situation” of atrophied soft tissues, stiff joints and less than adequate use of the limb. • CAUSES : 1. Premature loosening and failure of implants 2. prolonged use of immobilisation of limb during the healing of fracture. i.e. post operative Coaptation and immobilisation of the operated limb. 3. The above causes cause pain and decreased use of limb leading to fracture disease. PREVENTION: 1.Stable fixation to allow “early pain free mobilisation” or “weight bearing with out implant loosening”. 2.Positive Cycle of Healing supplements the OSTEOSYNTHSIS

2. INJURY TO NERVE- Causes Paralysis of muscles 3.Injury to Blood vessels : Impairment in blood supply to the dependent region. • Degeneration and atrophy of muscles. • Injury to Nutrient vessels and Periosteum • 4. Non union and Delayed union : Due to Defective reduction and Improper Immobilisation.

NONUNION: A fracture in which all evidence of OSTEOGENIC AVTIVITY at the fracture site has ceased , movement is present at the fracture site and union is no longer possible “with out surgical intervention.” The term “PSEUDOARTHROSIS” -is Some times applied to all non unions but reserved for those non unions in which Sclerotic bone ends are united by a fibrous “joint capsule” filled with serum.

• Diagnosis: > Radiographic evidence that bone healing is not occurring. • Non union occurs due to ???? 1. Inadequate immobilisation or failure to maintain immobilisation for a sufficient length of time. 2. Gap between the fracture segments is due to a) soft tissue interposition b) Malalignment of the fragments c) distraction of the fragments by traction or Improper use of internal fixation devices. d) Gap between the fracture segments is very wide.

• e) Lack of Immobilisation • f) Loss of Bone or bone fragments from open trauma or surgery. • g) Infection – causes Autolysis of Fibrin clot which interferes with callus formation. • h) Severe Comminition • i) Compound fracture – infection - NonUnion • 3. LOSS OF BLOOD SUPPLY BY • a) Damage to the nutrient vessels of bone. • b) Excessive periosteal stripping of bone or injury to the periosteum

Non union • CLINICAL SIGNS: • 1 Painful motion at the fracture site • 2. progressive deformity • 3. Disuse of Limbs and Muscle atrophy. • Radiographic signs of Non union.  wide gap between fracture segments .  Medullary cavity at both fracture ends closed and rounded off . Fracture healing stops .  Union will not occur without surgical intervention

The commonest cause of delayed and non union is inadequate immobilisation of the fracture.  Fracture healing will proceed -in the presence of a certain amount of tension and a considerable amount of Bending will also be tolerated.

 But Torsion or Rotation impedes healing Because it results in tearing of the Fibroblastic network of the Callus.

• Treatment of Non union. • Prime objective of treatment of non union is To Provide adequate fixation with the assumption that bone is capable of a Biological response. • Types Non Unions : 1. Biologically Active or Viable Non -Unions. 2. Biologically Inactive or Non –Viable Non -Unions.

 Biologically Active or Viable Non -Unions. There are of 3 types Most often seen in small animals. 1. Hypertrophic type or “Elephant foot” : is the commonest - seen as a complication of IM pinning of Humeral and Femoral shaft fracture. i) Due to rotational forces at the fracture site. ii) Abundant bridging callus that has not Ossified because of motion at the fracture site. iii) Unable to bridge the fracture gap due to Motion iv) Well Vascularised Elephant foot shaped callus develops which does not Bridge the fracture Gap.

V. Gap contains: Cartilage and Fibrous tissue. There is Sclerosis of Bone ends . Later Medullary Cavity Becomes sealed. TREATMETNT: Remove the IM pin . Freshen the edges of the bone fragments . Remove the Necrotic tissue By Debridement.  Cut the bony ends and flat surfaces are apposed and aligned Establish the Medullary canal. Rigid Immobilisation with compression Plating helps in Healing process.

• 2. SLIGHTLY HYPETROPHIC TYPE:  Instability following plate fixation - LEAD TO Non union – there is minimal callus formation. 3.OLIGOTROPHIC TYPE: No callus formation.  Fracture segments widely separated. And joined by Fibrous type only.  example : Avulsion type of fracture. ALL THE ABOVE THREE TYPES OF BIOLOGICALLY ACTIVE AND VIABLE TYPE NON UNION ARE TREATED BY AND HEAL BY RIGID INTERNAL FIXATION ONLY.

1.

2.

2.BIOLOGICALLY INACTIVE OR NON –VIABLE NON -UNIONS. THERE ARE 4 TYPES THE DYSROPHIC TYPE: Poorly vascularised fragments impedes fracture healingex: - seen as a complication of comminuted fracture. NECROTICE TYPE: Non-Viable fragments or sequestrae at the fracture site impede healing. Ex. Seen in comminuted or infected fractures.

• 3. The Defect type: • Removal of Dead bone or Sequestrae is too BIG to be Bridged by Normal Healing process. 4. The Atrophic type: This is the commonest and most difficult type of non union to deal with.  It is seen as a complication of fracture the Radius and ulna in Toy Poodles and Miniature breeds of dogs.  There is instability at the fracture site with loss of Osteogenic activity , Osteoporosis and eventually Osteolysis.

Shearing forces at the fracture site are thought to predispose to the Non-union of the Radius and Ulna and  And OCCUR at inadequate immobilisation with PLASTER OF PARIS CAST.  IT IS RECOMMENDED THAT FRESH FRACTURES OF RADIUS AND ULNA ARE TREATED IN SMALL BREEDS ARE TREATED BY RIGID PLATE FIXATION AND MINI COMPRESSION PLATES.

PRIME OBJECTIVE IN TREATING THE AVASCULAR NON UNIONS :  To Stimulate Osteogenesis.  Fracture is stabilised with BONE PLATING and CANCELLOUS BONE GRAFT.  CANCELLOUS Bone graft is collected from Proximal Humerus and wing of Ilium.  Bone graft is packed around the fracture site to stimulate the OSTEOGENESIS. OR  AMPUTATION IS PERFORMED IF NON UNION PERSISTS INSPITE OF THE ABOVE MEASURES FOLLOWED.

MALUNION • Defined as a fracture that has healed or is healing in an abnormal position. • CAUSES: • IMPROPER REDUCTION OR IMMOBILISATION DURING HEALING.

DELAYED UNION Definition : refers to a fracture that has not healed in the usual time for that particular fracture. The commonest cause of delayed union is • Inadequate or interrupted fixation of the fracture segments. • Repeated movements and lack of immobilisation interfere with mineralisation of callus. • Radiographic signs :the fracture line is evident and has a feathery or woolly appearance.

• Rectification: Proper and continued immobilisation. • If reduction is unsatisfactory, surgical intervention is indicated to correct deficiencies of reduction and fixation.

DISEASES AFFECTING BONE

BONE DISEASES         

Hypertrophic Osteodystrophy Craniomandibular osteopathy Panosteitis Multiple Cartilaginous Exostosis Hypertrophic Osteopathy Bone Cysts Hyperparathyroidism Vitamin D Deficiency(Rickets ,osteomalasia) Retained Cartilage Core

HYPERTROPHIC OSTEODYSTROPHY  Uncommon developmental disease of immature      

large and giant breeds of dogs. Swollen painful metaphyses. Disturbance in endochondral ossification in metaphyseal growth plates. Compromise of metaphyseal blood supply Secondary hemorrhage,inflammation,necrsis & fracture Periosteal response. Etiology is unknown.

HOD

DIGNNOSIS  Large & giant breeds of 2-8    

months of age Acute lameness Soft tissue swelling Double physeal line Differential diagnosis:panosteitis, hypertrophic osteopathy, craniomandibular osteopathy

CRANIOMANDIBULAR OSTEOPATHY  Nonneoplastic proliferative disease 0f    

growing animals Terrier breeds are prone to CMO (4 to 10M) Mandible, temporal & occipital bones are often involved Lamellar bone is replaced by woven bone. Woven bone is replaced by mature bone upon skeletal maturity…….self-limiting

DIAGNOSIS  Excess salivation ,dehydration ,wt loss    

& lethargy Difficulty in opening mouth even under general anesthesia Temporo-mandibular muscle atrophy Bilateral ,symmetrical, proliferative lesions of mandible DD:HOD,HO( Rarely affect the flat bones ),Bacterial or Fungal osteomyelitis

CMO

PANOSTEITIS  Self-limiting developmental disease of

young , large and giant breeds  Often seen in German shepherd  Primary disease of fatty bone marrow with secondary effects on the long bones  It is cyclical ;change involving degeneration of medullary adipocytes-stromal cell proliferation-osteoid production-secondary endosteal & periosteal response-restoration of fatty/hemapoietic marrow within 60-90 days

ETIOLOGY  Etiology is unknown  Reported possibilities :viral

& bacterial osteomyelitis, stress, transient vascular abnormalities ,metabolic disorders , parasitic migrations, autoimmune reactions allergic reactions & hyperestrinism

PANOSTEITIS

DIAGNOSIS  Acute lameness  5 to 12 month old German shepherd  Disease is episodic ,cycles

often occur at 2 to 3 wk intervals  Earliest radiographic sign is an increased radiolucency at nutrient foramen region  Medullary opacity in later stages

Rx

OF PANOSTEITIS

 Treatment is Supportive –use of analgesics  Client education –likelihood of recurrence of

disease process in different limbs  Excellent Prognosis as it is self-limiting  Complications :rarely chronic lameness & disease recurrence



MULTIPLE CARTILAGINOUS EXOSTOSIS(MCE)  Proliferative disease of bone seen in Dogs

Cats ,Horses ,and humans  Multiple ossified protuberances arise from cortical surfaces in the metaphyseal region of long bones ,in the vertebrae or in the ribs  MCE results from displacement and differentiation of chondrocytes from growth plate  Grows in size till physeal plate fuses

ETIOLOGY OF MCE  Unknown etiology

 Heritable disease in humans  Familial tendency has been reported in dogs

DIAGNOSIS  Occurs in young growing animals with open 

  

growth plates Multiple firm swellings in several locations of long bones Biopsy –various stages of hyaline cartilage and bone Radiogaphic examination –multiple bony nodules DD: Multiple Tumors based on age ,R/E &biopsy

RX OF MCE  Not necessary if there is no mechanical

interference  Local excision  Occasionally becomes malignant  Periodic radiographic evaluation

HYPERTROPHI OSTEOPATHY  H O is a condition that affects long bones  It is secondary to primary thoracic or

abdominal mass  Bony lesions Bilateral ,symmetrical swellings of all limbs  Synonyms are hypertrophic pulmonary osteoarthropathy , pulmonary osteoarthropathy, hypertrophic pulmonary osteopathy  Periosteal congestion followed by periosteal reaction due to increased peripheral perfusion

HYPERTROPHIC OSTEOPATHY

HYPERTROPHIC OSTEOPATHY

DIAGNOSIS OF HO  Most often associated with metastatic

pulmonary lesion  Gradual swelling of all four limbs with lameness-during early stages of primary disease  Metacarpal and metatarsal bones are often affected first  Later all long bones and pelvis ,mandible become involved

TREATMENT OF HO  Directed to recognition and elimination of

primary lesion  Radiographic survey of thorax and abdomen  Prognosis and complications depends on the nature of the primary lesion

BONE CYSTS  Benign , fluid-filled cavities      

rarely found in young ,large breeds of dogs Monostotic cysts Polyostotic cysts Aneurysmal cysts :very rare multi compartment cysts filled with blood Initial vascular insult result in venous obstruction Etiology is unknown Hereditary predisposition in Doberman pinschers

DIAGNOSIS  Monostotic & polyostotic

cysts occur in young animals  Large radiolucent defects in metaphysis or diaphysis  Results in pathologic fracture due to cortical thinning  Aneurysmal cyst –Soap Bubble appearance due to compartmentalization by trabecular bone and connective tissue

TREATMENT  Drainage ,curettage ,autogenous cancellous 

 



grafting Biopsy to distinguish bone cyst from neoplasia or infection Immobilization incase of pathologic fracture Prognosis is good if there is no joint involvement Guarded in case of aneurismal cysts as complete removal is difficult

HYPERPARATHYROIDISM  Low serum Ca levels triggers the release of

    

parathyroid hormone Target organs –bone ,kidney & intestine Osteoclastic bone resorption in bone Inhibits uptake of “P” by renal tubules &promotes excretion Hydroxylation of 25-hydroxycholecalciferol in the renal mitochondria Primary &secondary hyper parathyroidism PTH production/release increases with subsequent increased resorption of bone

DIAGNOSIS 1. Primary hyper parathyroidism –hyperplastic

parathyroid gland ,Neoplasia and hyperplasia 2. Renal secondary hyper parathyroidisminability of kidney to excrete “P”&Hydroxylate 25 –hydrxycholecalciferol Congenital renal insufficiency in young animals CRF is attributed in older animals

Nutritional secondary hyper parathyroidismresults from decreased “Ca” in diet increased “P” in diet ,decreased Vitamin D Ca binding agents in intestine

all-meat diet ,diet with abnormal Ca:P ratio

C/Signs :lameness,pathological fractures,growth abnormalities R/E:Resorption of the alveolar bone –mandible &maxilla  Loosening of teeth  Diffuse demineralization of entire skeleton  Thin cortices & loss of bone density

TREATMENT  In Renal Secondary Hyperparathyroidism

   



restoration of normal renal function Dietary protein restriction Phosphate-binding gels Supplementation with Ca’lactate or Ca’gluconate & vitamin D Prognosis is guarded-based on the stage of renal disease

In Nutritional Secondary Hyperparathyroidism  Oriented to Correction of the dietary imbalance of Ca & P  The Ca to P ratio should be 2:1  Prognosis is favorable  Complications are delayed unions and malunions

VITAMIN D DEFICTENCY RICKETS,OSTEOMALASIA  Vitamin D is necessary for the normal

absorption of Ca from intestine  Rickets occurs in immature animals with growth plates open ,osteomalacia in adult animals  In young animals Ca is necessary for bone growth maturation of the growth plates  In adult animals vitamin D deficiency prevents osteoclasts &osteocytes from responding to PTH

DIAGNOSIS  Lameness, stiff gait , deformity of long bones

and pathological fractures  Radiographic signs are similar to hyperparathyroidism  In immature animals growth plates may appear wider than normal with extension of cartilage cores in to metaphysis  Shortened bones and abnormal curvature of bones 

TREATMENT  Correction of dietary or

environmental abnormalities  Vitamin D supplementation ,but levels should not exceed 10 to 20 IU/Kg/Day  Growth plate abnormalities are permanent

RETAINED CARTILAGE CORE  RETAINED ENDOCHONDRAL CORE

RETAINED ENCHONDRAL CORE  Maturation defect of the hyaline cartilage in the metaphyseal growth plate  Rare but reported in the distal ulnar physes of large breeds  Resulted from defective endochondral ossification

DIAGNOSIS  Swollen metaphyseal area

 Cranial bowing of radius with external deviation of fore paw  Radiolucent defect extending proximally from distal ulnar growth plate  DD:HOD,HO

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