Chronic osteomyelitis

aetiology

Postinfective

· sequel to acute osteomyelitis

Posttraumatic

· usually following open fracture

· tibia most common

Postoperative

· usually following implantation

· internal fixation of fracture

· arthroplasty

Postinfective

pathogenesis

· usually due to

· incomplete treatment

· late treatment

microbiology

· due to original infecting organism

· usually Staph aureus

· often sensitive to penicillin or flucloxacillin

pathology

· combination of

· bone erosion

· cortical new bone formation

· subperiosteal new bone formation

· cavities containing

· pus

· pieces of dead bone (sequestra)

· surrounded by areas of sclerosis

· reactive new bone formation

· from cortex and periosteum

· overlying soft tissue

· usually indurated, puckered and adherent to bone

· often sinus connecting lesion to skin

complications

· pathological fracture

· from bone destruction and brittleness

· malignant transformation

· of bone to sarcoma

· of sinus to epithelioid carcinoma

clinical features

· recurrent flares consisting of

· pain and fever

· redness and tenderness

· discharging sinus

· seropurulent discharge

investigations

Radiology

Plain x-ray

· variable amounts of

· patchy loss of density

· surrounding thickening and sclerosis

· may see dense sequestrum

· bone often deformed

Bone scan

· increased uptake in lesion

· gallium or white cell scan may be useful

· more specific for infection

CT scan

· show bony architecture

· extent of bone destruction

· sequestra

· abscess cavities

Laboratory

Blood

· variable elevation in ESR and WCC with flares

Culture

· need to repeatedly culture organisms

· to idenify changing sensitivity

treatment

Antibiotics

· usually does not eradicate infection

· useful to

· control acute flares

· stop spread

Local treatment

· dressing of sinus

· incision and drainage of acute abscess

Surgery

Indications

· significant symptoms

· evidence of sequestrum

Procedure

· excision of involved skin

· debridement of all dead bone

· implantation of gentamicin-impregnated beads

· skin cover

· primary suture without tension if possible

· local or distant muscle flap if large defect

Posttraumatic

pathogenesis

· predisposed by

· tissue injury

· vascular damage

· oedema

· haematoma

· dead bone fragments

· open pathway to atmosphere

microbiology

· organism most commonly S aureus

· may be mixed

· S epidermidis

· coliforms

· Pseudomonas

· may see anaerobic organisms in contaminated wounds

· clostridia

· anaerobic streptococci

· Bacteroides

treatment

Principles

· appropriate antibiotics

· adequate debridement

· skeletal stability

· removal of implant if unstable

· replacement with alternative device

· early soft tissue cover

Prophylaxis

· thorough debridement

· delayed closure

antibiotics