AKT · Musculoskeletal/Metabolic bone & tumours

Osteomyelitis

Infection of bone — Staph. aureus commonest (Salmonella in sickle cell; TB; contiguous/diabetic-foot)

Overview

Infection of bone, by haematogenous spread (children — long-bone metaphysis; adults — vertebrae) or contiguous spread (diabetic foot, trauma, prosthesis). Staphylococcus aureus is the commonest organism; Salmonella is classic in sickle cell disease. MRI is the most sensitive imaging; treatment is prolonged antibiotics ± surgical debridement.

Recognise

Localised bone pain, tenderness, warmth and swelling ± fever; reluctance to weight-bear; a non-healing diabetic-foot ulcer probing to bone
Vertebral osteomyelitis: insidious back pain ± fever; risk of epidural abscess (neurological compromise)
Risk factors: diabetes, IV drug use, immunosuppression, sickle cell (Salmonella), prosthetic material, penetrating trauma

Red flags

Vertebral osteomyelitis with neurology (epidural abscess) → emergency MRI + surgical decompression
Diabetic foot ulcer that probes to bone → assume osteomyelitis

Differentials & how to tell them apart

Septic arthritisintra-articular infection — aspirate; can coexist

Charcot neuroarthropathydiabetic; deformity without infection — can mimic on imaging

Bone tumour / infarctionmalignancy or sickle infarct — biopsy/context distinguishes

Investigations

MRI is the most sensitive imaging (early marrow oedema; X-ray changes are late); blood cultures + inflammatory markers; BONE biopsy/culture for the organism (the gold standard to target therapy); probe-to-bone test in diabetic foot.

Management

Bone culture → prolonged targeted antibiotics ± surgical debridement

1Confirm with MRI and obtain a bone biopsy/culture (gold standard) plus blood cultures. Start prolonged antibiotics targeted to the organism (empirical anti-staphylococcal; cover Salmonella in sickle cell).Gate: Vertebral osteomyelitis with neurological signs (epidural abscess) → emergency MRI and surgical decompression; a diabetic-foot ulcer probing to bone = osteomyelitis.
2Surgical debridement for dead bone, abscess or prosthetic infection; address the source (diabetic foot offloading/revascularisation, glycaemic control); complete the prolonged antibiotic course.

Prolonged targeted antibiotics (often weeks, initially IV) — based on bone culture; empirical anti-staphylococcal cover (flucloxacillin; vancomycin if MRSA); cover Salmonella in sickle cell

Surgical debridement — for dead bone (sequestrum), abscess, prosthetic infection or failure of medical therapy

Source control / revascularisation — diabetic foot — offloading, vascular assessment, glycaemic control

Treat epidural abscess urgently — decompression + antibiotics

Key points

Localised bone pain + fever + raised inflammatory markers = osteomyelitis → MRI (most sensitive) + bone culture, then prolonged targeted antibiotics ± debridement. Staph. aureus usual; Salmonella in sickle cell. Diabetic ulcer probing to bone = osteomyelitis; vertebral disease can cause an epidural abscess.

Monitor & prognosis

Inflammatory markers/clinical response, repeat imaging, antibiotic course completion.

Curable with adequate antibiotics ± surgery; can become chronic with sequestra.

Source: BSR/IDSA; cross-ref child_health (sickle cell), endocrine (diabetic foot)