Osteomyelitis is an infection of bone and bone marrow that results in progressive inflammatory destruction, necrosis, and new bone formation. It may be acute or chronic and can occur at any age, though it is most common in children under 12 years.

The infection may involve:

• Cortex

• Medullary cavity

• Periosteum

• Adjacent soft tissues

Epidemiology

• More common in children (hematogenous spread)

• More common in adults with diabetes, trauma, or peripheral vascular disease

• Male predominance

• Increased risk in sickle cell disease

Etiology

Common Causative Organisms

1. Hematogenous Osteomyelitis (Children)

• Staphylococcus aureus (most common)

• Streptococcus species

• Kingella kingae (young children)

2. Sickle Cell Disease

• Salmonella species (classically associated)

• Staphylococcus aureus

3. Post-traumatic / Post-surgical

• Staphylococcus aureus

• Coagulase-negative staphylococci

• Gram-negative bacilli

4. Tuberculous Osteomyelitis

• Mycobacterium tuberculosis

Classification

1. According to Duration

• Acute (< 2 weeks)

• Subacute

• Chronic (> 6 weeks)

2. According to Route

• Hematogenous

• Contiguous spread

• Direct inoculation (trauma/surgery)

3. According to Host Status

• Normal host

• Compromised host (diabetes, immunosuppression)

Pathophysiology

1. Bacterial entry into bloodstream or direct inoculation

2. Seeding of metaphysis (especially in children)

3. Inflammatory response

4. Increased intraosseous pressure

5. Vascular compromise

6. Bone necrosis → sequestrum formation

7. New bone formation around dead bone → involucrum

8. Chronic sinus tract formation

Risk Factors

• Trauma

• Open fractures

• Diabetes mellitus

• Peripheral vascular disease

• Immunosuppression

• Intravenous drug use

• Sickle cell disease

Clinical Features

Acute Osteomyelitis

• Fever

• Malaise

• Severe localized bone pain

• Swelling

• Redness

• Warmth

• Limited movement

• Refusal to bear weight (children)

If infection is near a joint:

• Sympathetic joint effusion

• Restricted movement

Chronic Osteomyelitis

• Persistent pain

• Sinus tract discharge

• Bone deformity

• Recurrent flares

• Low-grade fever

Diagnostic Criteria

Diagnosis is based on:

1. Clinical suspicion

2. Laboratory evidence

3. Imaging

4. Microbiological confirmation

Investigations

1. Laboratory Tests

• Total and differential WBC (leukocytosis)

• CRP (elevated early and sensitive)

• ESR (elevated)

• Blood culture and sensitivity

• Urine culture if indicated

• Pus culture and sensitivity

2. Imaging

Plain X-ray

• May be normal first 10–14 days

• Later shows:

  • Periosteal elevation

  • Lytic lesions

  • Sequestrum

  • Involucrum

MRI (Best early modality)

• Detects marrow edema

• Soft tissue abscess

CT Scan

• Defines cortical destruction

Bone Scan

• Useful in early disease

Differential Diagnosis

• Septic arthritis

• Bone tumor

• Cellulitis

• Ewing sarcoma

• Sickle cell bone crisis

Treatment

Management requires:

• Early antibiotic therapy

• Surgical intervention when indicated

• Long duration therapy

Pharmacological Treatment

Acute Osteomyelitis

Empiric Therapy (IV)

Cloxacillin

• 1–2 g IV every 6 hours

OR

Clindamycin

• 600 mg IV every 8 hours

Duration:

• Typically 4–6 weeks

• May stop at 3 weeks if clinical and radiological resolution

Switch to oral therapy once improved.

Chronic Osteomyelitis

• Surgical debridement is essential

• Long-term targeted antibiotics (based on culture)

• Antibiotics alone usually insufficient

Osteomyelitis in Sickle Cell Disease

Ampicillin

• 2 g IV every 6 hours (5–12 weeks)

PLUS

Cloxacillin

• 1–2 g IV every 6 hours (6–12 weeks)

PLUS

Chloramphenicol

• 500 mg IV every 6 hours (if Salmonella suspected, 2–3 weeks)

Septic Arthritis

• Cloxacillin for 6 daysOR

• Clindamycin for 7 days

Plus urgent joint drainage.

Gonococcal Arthritis

Caused by Neisseria gonorrhoeae

Treatment:

• Benzyl penicillin 2.5–5 MU IV every 6 hours for 3 daysOR

• Kanamycin 2 g IM daily for 3 days (if resistant)

Open Fracture (Prophylaxis)

• Cloxacillin 1 g IV every 6 hours for 3 daysOR

• Clindamycin 600 mg IV every 8 hours for 3 daysPLUS

• Ceftriaxone 1 g IV every 8 hours for 3 days

Non-Pharmacological Management

Acute Osteomyelitis

• Surgical drainage (recommended if >24 hours history)

• Debridement of necrotic tissue

• Immobilization of limb

• Elevation

Septic Arthritis

• Urgent surgical drainage

• Repeated joint aspiration if necessary

Complications

• Chronic osteomyelitis

• Pathological fracture

• Growth disturbance (children)

• Septic arthritis

• Sepsis

• Amputation

• Squamous cell carcinoma in chronic sinus tract

Prognosis

• Early treatment → good outcome

• Delayed treatment → chronic infection

• Higher recurrence in diabetics

Prevention

• Early treatment of wounds

• Proper open fracture management

• Strict aseptic surgical technique

• Glycemic control in diabetics

• Vaccination (prevent systemic infections)

• Prompt treatment of bacteremia

Patient Education

• Complete antibiotic course

• Monitor wound site

• Report fever or recurrence

• Follow up imaging

• Strict diabetes control