Osteomyelitis

Question 1

Define osteomyelitis

Answer 1

Inflammatory condition of the one caused by infection of the metaphysis of long bones

Question 2

Aetiology of osteomyelitis

Answer 2

Haematogenous spread or inoculation (direct trauma)
Most common organism: Staphylococcus aureus
- Other: Streptococci (group A and B), H. influenzae. Kingella Kingae, TB
- Occasionally, there are multiple foci e.g. disseminated staphylococci or H. influenzae infection

Commonly affects the distal femur and proximal tibia (but any bone may be affected)

Question 3

Risk factors for osteomyelitis

Answer 3

<5yo
Sickle cell disease (esp. staphylococcal and salmonella)
Immunodeficiency disorders
Diabetes Mellitus
Sepsis
Minor trauma with bacteraemia
Indwelling vascular catheters

Question 4

Symptoms of osteomyelitis

Answer 4

Fever
Acute onset limb pain
Immobile limb (pseudoparesis) - movement causes severe pain
Skin swollen, tender, erythematous
Back pain (vertebral infection)
Limp or groin pain (infection of the pelvis)

Question 5

Signs of osteomyelitis on examination

Answer 5

Fever

Joint examination
- Skin swollen, tender, erythematous
- Immobile limb (pseudoparesis) - movement causes severe pain

Question 6

Investigations for osteomyelitis

Answer 6

Sepsis 6 + screen

Urine dip/MC&S

Blood cultures
FBC
CRP
U&Es
LFTs
VBG

X-ray affected joint:
- Early: normal
- Later (>7 days): osteopenia, bone destruction, subperiosteal new bone formation
- Moth sign = Brodie abscess
Joint aspiration + MC&S
US affected joint: periosteal elevation
MRI affected joint: ?infection
CXR: septic screen

Question 7

Management for acute osteomyelitis

Answer 7

2 High-dose IV empirical antibiotics → narrow spectrum antibiotics (usually for 2-4 weeks):
Adults: vancomycin + ceftriaxone IV
Diabetes/paeds: Flucloxacillin + penicillin/fusidic acid
- Second line: Clindamycin (PenAll), vancomycin (MRSA)

Immobilise the affected limb
Analgesia e.g. paracetamol/NSAID
CRP returns to normal → switch to oral antibiotics for 6 weeks

No response to Abx 24-48h after treatment / dead bone / biofilm→ surgical drainage

Question 8

Management for chronic osteomyelitis

Answer 8

> 2 weeks
Clinical assessment, disease staging (Cierny-Mader classification) and optimisation of comorbidities
Surgical debridement
IV antibiotics
Functional rehabilitation

Question 9

Complications of osteomyelitis

Answer 9

Can spread to cause septic arthritis in sites where the joint capsule is inserted distally to the epiphyseal plate e.g. the hip
Fracture
Neurological impairment secondary to abscess or bony collapse
Growth disturbance - premature physeal closure, resulting in short limbs or angular deformity if only partial physeal arrest occurs.
Amputation
Joint stiffness
Infection recurrence

Question 10

Prognosis of osteomyelitis

Answer 10

> 95% have complete resolution with treatment