BONE AND JOINT INFECTION Dr.Syed Alam Zeb Orthopaedic Unit HMC

AETIOLOGY Staphylococcus aureus is overall the most common. Beta haemolytic streptococci and anaerobes may cause acute infection. E-coli and B. streptococci are more common in children. Aerobic gram negative rods may cause infection in the elderly.

PATHOGENESIS OF BONE AND JOINT INFECTION Healthy bone is resistant to infection. Open fractures provide an ideal focus for infection. Organisms can lie latent in dead bone(sequestrum). Involucrum is healthy new bone formed in a shell around dead and infected bone.

ACUTE SEPTIC ARTHRITIS The history is short with the patient generally very unwell. Young children do not move the involved limb. In older patients the joint is extremely painful to move. The affected limb is hot and red. Night and rest pain are characteristic.

ACUTE OSTEOMYELITIS Present like acute arthritis. There is fever, loss of function and localized pain. In young children the presentation may simply be refusal to weight bear or use a limb. The affected part is hot, tender and red.

CHRONIC OSTEOMMYELITIS Usually follow an episode of acute infection or an open fracture. Pain at rest especially night pain. Swelling, ulcer or sinus may be present. Bony tenderness is common. Systemic features are minimum.

DIABETIC FOOT OSTEOMYELITIS Neuropathy, vasculopathy and high blood sugar leads to ulcer formation. Bones become secondarily involved. Chronic non-healing infection result in soft tissue and bony loss. Control of diabetes, improving the nutritional status and regular debridements are required.

Investigations for acute osteomyelitis and septic arthritis WBC count and CRP are high, ESR may be very high. Changes on plain x-rays are not visible for some time. US can pick pus. Isotope scans are sensitive but not specific.

Investigations for acute osteomyelitis and septic arthritis CT may show bone erosions. MRI is very helpful. Culture and sensitivity is invaluable. Histology of infected bony tissue sometimes required.

MANAGEMENT

Osteomyelitis In acute osteomyelitis put the patient on iv antibiotics and pain killers. Early diagnosis reduces the risk of infection becomes chronic. Surgery required to remove infected tissues and to obtain material for culture.

Chronic Osteomyelitis When acute infection is not treated properly it can lead to destruction of bone. The combination of dead bone with pus formation and discharging sinuses on the skin is called Chronic osteomyelitis. Treatment is debridement of the dead bone and soft tissues and regular cleaning.

Septic Arthritis Joints should be aspirated before treatment is started. Antibiotics started empirically then changed according to the culture results. Treatment should last several weeks starting with iv antibiotics. If infection recurs the joint may need to be opened and any loculi washed out.

Chronic arthritis All dead and foreign tissues must be excised Secure implants may be left but all suspect soft tissues must be excised. Antibiotic- impregnated beads or spacer may be put in to the joint space. Blood levels of antibiotic needs regular checking.