Osteomyelitis is a bone infection characterized by progressive inflammatory destruction after formation of new bone. It may be chronic or acute. It commonly results from a combination of local trauma—usually trivial but causing a hematoma—and an acute infection originating elsewhere in the body. Although osteomyelitis usually remains localized, it can spread through the bone to the marrow, cortex, and periosteum. Possible consequences include amputation of an arm or leg when resistant chronic osteomyelitis causes severe, unrelenting pain and decreased function due to weakened bone cortex. Acute osteomyelitis is usually a blood-borne disease and most commonly affects rapidly growing children. Draining sinus tracts and widespread lesions characterize chronic osteomyelitis, which is rare.
Osteomyelitis occurs more often in children (especially boys) than in adults—usually as a complication of an acute localized infection. The most common sites in children are the distal femur and the proximal tibia, humerus, and radius. The most common sites in adults are the pelvis and vertebrae, generally after surgery or trauma.
Incidence of osteomyelitis is declining, except in drug abusers. With prompt treatment, prognosis is good for acute osteomyelitis but remains poor for chronic osteomyelitis.
· Minor traumatic injury
· Acute infection originating elsewhere in the body
· Staphylococcus aureus (most common)
· Streptococcus pyogenes
· Pneumococcus species
· Pseudomonas aeruginosa
· Escherichia coli
· Proteus vulgaris
· Pasteurella multocida (part of normal mouth flora in cats and dogs)
Typically, a pathogen finds a culture site in a hematoma after recent trauma or in a weakened area, such as the site of local infection (for example, furunculosis), and travels through the bloodstream to the metaphysis, the section of a long bone that's continuous with the epiphysis plates, where the blood flows into sinusoids. Pus is produced and pressure builds in the rigid medullary cavity. An abscess forms and the bone is deprived of its blood supply. Necrosis results and new bone formation is stimulated. Dead bone detaches and exits through an abscess of the sinuses and osteomyelitis becomes chronic.
Signs and symptoms
· Sudden pain and tenderness in the affected bone
· Swelling, restricted movement of surrounding soft tissues
· Chronic infection presenting intermittently for years, flaring after minor trauma or persisting as drainage of pus from a pocket in a sinus tract
· Chills, nausea, and malaise
· Drainage of pus
Diagnostic test results
· White blood cell count and erythrocyte sedimentation rate are elevated.
· Blood cultures show causative organism.
· X-ray may not show bone involvement until disease has been active for 2 to 3 weeks.
· Magnetic resonance imaging delineates bone marrow from soft tissue.
· Bone scans detect early infection.
· Immobilization of affected body part by cast, traction, or bed rest
· Supportive measures, such as analgesics for pain and I.V. fluids to maintain hydration
· Incision, drainage, and culture of an abscess or sinus tract
· Systemic antibiotics
· Intracavitary instillation through closed-system continuous irrigation with low intermittent suction
· Limited irrigation; blood drainage system with suction (Hemovac)
· Packed, wet, antibiotic-soaked dressings
· Surgery to remove dead bone and promote drainage (prognosis remains poor even after surgery)
· Hyperbaric oxygen
· Skin, bone, and muscle grafts
STAGES OF OSTEOMYELITIS