Musculoskeletal System Monday, July 06, 2009 9:27 AM
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Osteoblast ○ bone marrow forming cells ○ Lay down new bone and become… Osteocytes ○ Parathyroid hormone. ○ Osteoblast - trapped in bone matrix ○ Maintains bone makers. Osteoclast ○ Removes bone during repair and remodeling process ○ Reabsorb bone - use citric and lactic acid to do it. Bone Matrix ○ Collagen fibers • Give bone matrix strength ○ Proteoglycans • Large polysacchrides give strength to bone. • Important for movement of ions. ○ Glycoprotein complexes Bone Mineralization ○ Synthesized and bone minerals are laid down. ○ Final hardening of bone Types of bone ○ Compact Bone • Highly organized, very strong • Organized by haviristim system. ○ Spongy Bone • Less complex organization of bone tissue ○ Periosteum • Double layer of CT Outer layer has blood vessels and nerves. Inner layer has collagen fibers that penetrate into bone. Hormonal Control of Bone ○ Parathyroid Hormone • Important Ca & phosphate regulator • Helps Ca and phosphate be released from bone tissue. ○ Calcitonin • Helps regulate release of Calcium (Ca) from bone. • Released from thyroid gland. ○ Vitamin D • Steroid hormone, helps absorb Ca from intestine, get from intestinal digestion and sun. • Activates Parathyroid Hormone. Maintenance of Bone Integrity ○ Remodeling: maintains internal structure
Used for microscopic injuries in bone Phase 1 (activation) Stimulis - hormone, drug, physical stressor activates body to form osteoclasts. • Phase 2 (resorption) Osteoclasts gradually reabsorb bone • Phase 3 (Formation) Laying down of new bone by Osteoblasts lining walls of injured site. ○ Repair Larger wounds • Hematoma formation Blood clot over ends of bony tissue • Formation of procallus by osteoblasts Sits up from bone tissue, forms seal over end of bone (by osteoblasts) Happens within days of injury Form bone matrix • Callus formation Takes a few weeks to form. Structural integrity • Replacement and contour modeling Can take years (up to 4 yrs) Bone broken down (lysed), then mineralized. Structure and Function of Joints • Stabilize and move ○ Synarthrosis • Completely immovable, i.e. Skull. ○ Amphiarthrosis • Slightly movable, where sternum and ribs come together ○ Diarthrosis • Freely movable, knees, hips, elbows. ○ Fibrous Joints • Connected by fibrous CT, usually synarthrosis. • Depends on how far apart the two bones are. • Radius ulna, teeth to mandible. ○ Cartilaginous Joints • Connected by cartilage. • 2 types Symphysis type joints (pad or disc b/t bones, pubis, intervertebral discs) Synchondrosis type joints (have hyaline cartilage, costal cartilage b/t ribs and sternum) ○ Synovial Joints • Diarthrosis joints, most movable and most complex. • Uniaxial Move in one direction •
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Biaxial Move in two directions - finger • Multi Axial Multiple planes - Hip MSK injuries and Skeletal Trauma classification ○ Fractures • Complete Fracture • Incomplete Fracture • Open Fracture • Closed Fracture • Comminuted Fracture 2 or more areas • Liner Fracture Parallel to axis of bone • Oblique Fracture Oblique angel to bone • Spiral Fracture Encircles bone • Tansverse Fracture Goes straight across bone ○ Pathologic Fracture • Break in bone tissue where there has been a preexisting abnormality or underlying disease issue. Tumors, osteoporosis, infex of bone, metabolic bone disorders. ○ Stress Fracture • Occurs in normal or abnormal bones. • Repeated stress on bone. • Often in athletes ○ Repair is as described earlier. Fractures ○ Clinical Manifestations • Pain, swelling, loss of function, deformity if not treated. ○ Diagnosis • Xray and full history • Underlying cause. • Mechanism of injury ○ Treatment • Reduction and internal fixation, manual pressure/manipulation, closed procedure. • Surgically, controlled situation • Immobolization, splints, calfs, traction, external fixation devices ○ Bone Healing • See above Osteoporosis ○ Pourous bone • Structural integrity compromised, decreased mineralization.
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Usually in cortical (compact) bones (more porous, thinner to start with) Compact bones - makes up majority of bone structure. Femur, radius, ulna. • More prone to fracture. ○ Peak bone mass reached at age 30 • Start to reabsorb bone mass. • Slow at first, then increases as we age. ○ Progressive bone loss • Can fracture spontaneously • Most pronounced in wrist, hip, spine. Will scan in wrist to check (cheaper) ○ Risk Factors? • Post-menopausal women. Possibly due to Drop in Estrogen production, increases amount of osteoclasts. Increased age • • Not active. • Women. • Caucasian or Asian increased chance. • Smaller body build. ○ Manifestations: pain and bone deformity. • Silent process - don't know unless get a scan. Until bone deformity occurs. Microfractures in spine, shorter, pain. • Simple fall can break hip, shoulder, arm, etc. Osteomyelitis • Infex of bone tissue ○ Endogenous and Exogenous source • From in or outside body. • Usually by bacteria, sometimes funguses, parasites, viruses. • From skin, sinus, ear, and dental infex's. ○ Travel by arteries, veins, lymph ○ Provokes and intense inflammatory response in bone tissue ○ Disrupts/weakens the (bone) cortex, predisposing to fracture. ○ Manifestations vary with age, site, initiating event, infecting organism, and whether it is acute, sub-acute, or chronic. • Fever, malaise, fatigue, some anorexia, weight loss, pain around infected area, edema at area (maybe). • Common in people with Wounds that don't heal. • Ankle, toe, knee. Osteoarthritis (OA) ○ Degenerative Joint Disease • Non-inflammatory joint disease. • Loss of articular cartilage. ○ Pathologic Characteristics • Erosion of Articular Cartilage • Sclerosis of bone underneath the cartilage
Cause pain. Formation of bone spurs. Cause pain. ○ Risk Factors? • More severe in women. • Joint stress, repetitive • Trauma leading to joint instability. • Idiopathic forms - don't know why it occurs (most common) • Age increases risk. ○ Signs/Symptoms? • Neck and back, wrists/hands, legs feet. • Larger joints then moving to smaller joints. ○ A slow progressive disease ○ Affects weight-bearing joints. ○ Pain with activity ○ <30 minutes of morning stiffness ○ Crepius • Popping sensation Rheumatoid Arthritis (RA) ○ A Systemic. chronic auimmune disorder of unknown etiology • Think neutrophils, macrophages, etc come to effected joints and start phagocytosis on immune complexes at joint, releasing enzymes that destroy joint cartilage. • Inflammatory response - perpetuates immune response. ○ Primary site of pathology is the synovium of the joints ○ Begins Insidiously • Slower onset ○ Pain with movement and joint tenderness ○ Criteria for RA • Morning stiffness for at least an hour. • Symmetrical, happens on both wrists. • Often effects hands • Get subcutaneous nodules • Positive blood markers (rheumatoid factor) Fibromyalgia ○ Chronic M/S Syndrome • Unknown cause, flu like symptoms beforehand. • Some tie in to chronic fatigue syndrome. • Some also have HIV, Lime's disease. ○ Diffuse Pain, Fatigue, Tender points • Parts on body, buttocks, shoulder where pain is diffuse, won't correlate with any other process that is occurring. • Debilitating chronic lfatigue syndrome. ○ Always have normal lab test (ESR.ANA,RA) ○ Other Symptoms? • Headache, memory loss, irritable bowel symptoms •
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• Sensitivity to cold (Reynod's Syndrome?), hands blanch. • Depression and anxiety. Congenital Defects Osteogenesis Imperfecta • Brittle bone Disease • Genetic, either autosomal dominant or autosomal recessive process determines how disease is classified and how severe. ○ Clinical Maniestations • Osteopenia Recurring fractures, can happen when picking up child. Short triangular shaped face. Blue sclera (white part of eye), poor dentition of teeth. Increased rate of aortic aneurisms. • Increased rate of fractures ○ Treatment: Surgery ○ Often mistaken as child abuse in mild cases of OI. Juvenile Rheumatoid Arthritis ○ Like adult version ○ Large joints most commonly affected • Can stiffen and contracture. • Can be damaged or altered altering how joint grows as child ages. • Joint stiffness following rest. • Decreased physical activity, weakness in muscles. • Effects all children differently - some will have many symptoms, some will have mild cases. ○ Chronic Uveitis (in eye) is common ○ Serum test for RF (Rheumatoid Factor) may be negative ○ Subluxation and ankolysis may occur in cervical spine • Deformity of cervical spine, not aligned properly. ○ RA that continues through adolescence can have severe effects in growth and morbidity.