Orthopaedic Infections

ORTHOPAEDIC INFECTIONS Eugene Sherry, MD, MPH, FRACS.  

 

 

Soft Tissue Infections Cellulitis - An inflammatory infection of the subcutaneous tissues, usually due to staph or strep (and Haemophilus in children). Local erythema, tenderness, and occasionally lymphangitis/lymphadenopathy make up the clinical picture. (Fig).Ordinarily, mild cases of cellulitis can be treated with an Lawn mower injury to arm: prone to cellulitis, gangrene, and oseteomyelitis from implanted debris

oral penicillinase-resistant penicillin or cephalosporin. Patients with high fever, systemic toxicity, poor host resistance, or underlying skin diseases should be admitted for IV antibiotic therapy. Significant Streptococcal Infections - Several serious diseases are related to specific streptococcal infections. Erysipelas - Group A strep causes this progressively enlarging, red, raised, and painful plaque seen preominately in infants, diabetics, elderly, and patients with predisposing skin ulcers. Severe toxicity, fever, leukocytosis, and bacteraemia are common. Treatment with high doses of IV penicillin is essential for this life-threatening disease. Necrotising Fasciitis - Aggressive, life-threatening fascial infection that is often associated with underlying vascular disease (esp. diabetes). Meningococcal septicaemia causing gangrene of four limbs and necessary ampuatations

Gas Gangrene - Classically caused by Clostridia species (G+ rod), but also can develop from G - and sometimes G+

Meningococcal septicaemia

(strep) infections. Clinical presentation usually includes

causing gangrene of four

progressive pain; edema (distant from wound); foul smelling,

limbs and necessary

serosanguineous discharge; and feeling of impending doom.

ampuatations

May be associated with bowel cancer. Radiographs typically show widespread gas in tissues. Treatment with high-dose penicillin (and aminoglycoside and cephalosporin), hyperbaric oxygen (inhibits toxins), and surgical I&D are required. See Fig. Tetanus - Don’t ever forget. Potentially lethal neuroparalytic disease caused by an exotoxin of Clostridium tetani, a G+ anaerobic rod. Treatment is centred on prophylaxis with proper wound care and tetanus toxoid administration (and TIG for patients with severe wounds and without known previous immunisations). Late management is largely symptomatic. Toxic Shock Syndrome - Severe staph infection that usually develops postoperatively. Surgical Wound Infection - There has been a recent increase in the incidence of Staph, epidermidis wound infections. Staph. aureus is still the most common infection overall, and in trauma patients. Methicillin-resistant staph species infections are also increasing. Puncture Wounds of the Foot - Commonly are infected with Pseudomonas (from shoewear), and require aggressive debridement and appropriate antibiotics. Common in children. Fungal infections. Human Immunodeficiency Virus (HIV) Infection - Incidence is increased in the homosexual population but becoming increasingly common in heterosexual patients. Additionally, well over half of the haemophiliacs population is affected. HIV positivity is not a contraindication to performing required surgical procedures. Hepatitis.

Hepatitis A. Hepatitis B. Non-A, Non-B Hepatitis. Hep C. Bone and Joint Infections Acute Hematogenous Osteomyelitis - Bone and bone marrow infection is caused (most commonly) by blood-borne organisms. Commonly affects children (boys>girls). Staph. aureus is the most common offender. Anaerobic infections are also frequently seen, with Peptococcus magnus (G+) appearing more frequently than Bacteroides (G-). The infection is most common in the metaphyses or epiphyses of long bones (lower extremity > upper extremity). Radiographic changes include soft tissue swelling early, demineralisation (10 days to 2 weeks), and sequestra (dead bone with surrounding granulation tissue) and involucrum (periosteal new bone) later (see POT.....). Pain, loss of function, and sometimes a soft tissue abscess are present. Elevated WBC count and ESR and positive blood cultures are usually seen. Bone scan (delayed up-take in bone) + gallium (in spine infections) or indium (in extremity infections) scans may be helpful in equivocal cases. MRI shows changes usually before plain films (nonspecific low signal intensity in marrow spaces on both T1 and T2 images). Aspiration is helpful for antibiotic choice. IV antibiotics followed by a course of oral antibiotics after the temperature has normalised (total of 6 weeks or until the ESR returns to normal), immobilisation, and for refractory cases surgical drainage (saving bone from further destruction) are usually curative. Recurrence is high for metatarsal lesions (50%), around (25%). Long term morbidity is >25%. Subacute Osteomyelitis - Usually discovered radiologically in a patient with a painful limp and no systemic (and often no local) signs or symptoms, often from partially treated acute

osteomyelitis, occasionally developing in a fracture haematoma. Unlike acute osteomyelitis, WBC count and blood cultures are frequently normal. ESR, bone cultures, and radiographs are often useful. Most commonly affects the femur and tibia, and unlike acute osteomyelitis, it can cross the physis even in older children. Radiographic changes include Brodie’s abscess, a localised radiolucency usually seen in the metaphyses of long bones. It is sometimes difficult to differentiate from Ewing’s sarcoma. When localised to the epiphysis only, other lesions (such as chondroblastoma) must be ruled out. Epiphyseal osteomyelitis is caused exclusively by Staph. aureus. Treatment of Brodie’s abscess in the metaphysis includes surgical curettage. Epiphyseal osteomyelitis requires surgical drainage only if pus is present (48 hours of IV antibiotics followed by 6 weeks of oral antibiotics is curative otherwise). Chronic Osteomyelitis - Can follow inappropriately treated acute osteomyelitis, trauma, or soft tissue spread, especially in the elderly, immuno-suppressed, diabetics, and IV drug abusers (Cierney type C host). Staph. aureus, G- rods, and anaerobes are frequent offending organisms. Often classified anatomically (Cierney). Skin and soft tissue are often involved, and fistulous tracts can occasionally develop into epidermoid carcinoma. Periods of quiescence are often followed by acute exacerbations. Nuclear medicine studies are often helpful in determining activity of disease. Combination IV antibiotics (based on deep cultures), surgical debridement, bone grafting (open, vascularized, or bypass [proximal and distal to infected area]), stabilisation (avoid IM devices following external fixator use with associated pin tract infections), and soft tissue coverage (flaps) are often required. Amputations are still often necessary. (See POT). Chronic Sclerosing Osteomyelitis - An unusual infection that involves primarily diaphyseal bones of adolescents. Septic elbow in a child

Chronic Multifocal Osteomyelitis - Caused by an infections agent appearing in children without systemic symptoms. Osteomyelitis with Unusual Organisms - Radiographs show

characteristic features in syphilis (T. pallidum; radiolucency in metaphysis from granulation tissue) and tuberculosis (joint destruction on both sides of a joint). Histology can also be helpful (e.g. tuberculosis with granulomas and Langerhan’s giant cells).

Septic Arthritis - Commonly follows hematogenous spread or extension of osteomyelitis; can also follow diagnostic or therapeutic procedures. Bacteria have a special affinity to exposed collagen matrix. Most cases involve infants (esp. hip), and children (knee). Fig. Septic elbow young child. There is pain, swelling, redness and pseudo-paralysis (won’t move arm). Pus drained. RA (tuberculosis) and drug abuse (Pseudomonas) can predispose adults. Haemophilus influenzae is the most common organism in children <5 yo (Rx chloramphenicol or a third-generation cephalosporin), staph in children >5 yo (Rx methacillin or oxacillin), and gonococci in adults (penicillin). Third-generation cephalosporins (ceftraidime, cefsulodin, and aztreonam) are now favored over aminoglycosides (with the possible exception of gentamicin) for the treatment of G- infections. Surgical drainage (often arthroscopically) or daily aspiration is the mainstay of treatment. Open drainage is required for septic hip joints. SI joint sepsis is unusual but is best diagnosed by physical examination (Flexian Abduction External Rotation - FABER most specific) and aspiration. A panus (much like in inflammatory arthritis) can be seen in tuberculosis infections. Late sequellae of septic arthritis include soft tissue contractures that can sometimes be treated with soft tissues procedures such as quadricepsplasty. Antibiotics Antibiotic Delivery Antibiotic Beads or Spacers.

Osmotic Pump. Home IV Therapy - useful and cheaper than hospital care. Other infections Infected Total Joint Arthroplasty - Perioperative IV antibiotics are the most effective method of decreasing incidence, but good operative technique, laminar flow (avoiding obstruction between the air source and operative wound), and special space suits also have a role. The ESR is the most sensitive indicator of infection, but it is nonspecific. Culture of hip aspirate is very sensitive and specific. C-reactive protein may be helpful. Marjolin’s Ulcer - Squamous cell carcinoma that develops in patients with chronic drainage from sinus tracts. Seen in untreaded chronic osteomyelitis. Nutritional Status and Infection - Nutrition is critical in decreasing the incidence of postoperative infection. Malnutrition is common after trauma. (See POT). Postsplenectomy Patients - Need vaccination of meningococcal and H. influenzae infections.