1. Infection of the bone and joint

2. Osteomyelitis Acute osteomyelitis usually occurs in children
Usually a haematogenous infection from distant focus
Organisms responsible include:
Staph. aureus
Strep. pyogenes
H. influenzae
Gram-negative organisms
Salmonella infections are often seen in those with sickle-cell anaemia
Infection usually occurs in metaphysis of long bones

3. Pathology
Acute inflammation results in raised intraosseous pressure and intravascular thrombosis
Suppuration produces a subperiosteal abscess that may discharge into soft tissues
Spread of infection into epiphysis can result in joint infection
Within days bone death can occur
Fragments of dead bone become separated in medullary canal (sequestrum)
New bone forms below stripped periosteum (involucrum)
If infection rapidly controlled resolution can occur
If infection poorly controlled chronic osteomyelitis can develop

5. Presentation Child usually presents with pain, malaise and fever
Often unable to weight bear
Early signs of inflammation are often few
Bone is often exquisitely tender with reduced joint movement
Late infection presents with soft-tissue swellings or discharging sinus
Diagnosis can be confirmed by aspiration of pus from abscess or metaphysis
50% of patients have positive blood cultures

6. Radiology X-rays can be normal during first 3 to 5 days
In the second week radiological signs include:
Periosteal new bone formation
Patchy rarefaction of metaphysis
Metaphyseal bone destruction
In cases of diagnostic doubt bone scanning can be helpful

8. Management
General supportive measures should include intravenous fluids and analgesia
Painful limb often requires a splint of skin traction to relieve symptoms
Aggressive antibiotic therapy should be instituted
Flucloxacillin is often the antibiotic of choice
If fails to respond to conservative treatment surgery may be required
A subperiosteal abscess should be drained
Drilling of metaphysis is occasionally required
Overall, about 50% of children require surgery

9. Complications
Metastatic infection can occurs at distant sites (e.g. brain, lung)
Spread into joint can result in a septic arthritis
This complication occurs in:
Young children in whom the growth plate is permeable
Bones in which the metaphysis is intracapsular
Epiphysis of bones involved in metastatic infection
Involvement of physis can result in altered bone growth
Failure to eradicate infection can result in chronic osteomyelitis

10. Septic arthritis

11. Septic arthritis Acute inflammatory condition of a joint
Usually results from bacterial infection
Untreated it will lead to destruction of the articular cartilage
50% cases occur in children less than 3 years of age
In infants less than one year old the hip is the commonest joint involved
In older children the knee is the commonest joint affected
10% of patients have multiple joints involved

12. Microbiology

13. Microbiology Organism can enter joint via a number of routes
Penetrating wound
From epiphysis or metaphysis
Haematogenous spread
Provoke an acute inflammatory response
Large number of neutrophils accumulate in joint
Release proteolytic enzymes that break down the articular cartilage
Results in joint effusion and reduced synovial blood supply

14. Complications Avascular necrosis of epiphysis
Joint subluxation / dislocation
Growth disturbance
Secondary osteoarthritis
Persistent or recurrent infection

15. Clinical features Exact presentation depends on age
Children are usually systemically unwell
Present with pain in the affected joint
All movements of the joint are painful
Reluctant to stand on weight-bearing joints
Affected joint is usually swollen, red and warm
Hip involvement results in flexion and external rotation
In adults septic arthritis is usually associated with immunosuppression

17. Ix Key investigation is culture of a joint aspirate
Should be performed prior to the administration of antibiotics
Other appropriate investigations should include
Inflammatory markers
Plain x-rays
Bone scan

20. DD
Irritable hip
Perthe's disease
Osteomyelitis
Gout
Pseudogout

21. Mx Antibiotics should be started after joint aspiration
Empirical therapy should be commenced based on likely organisms
Adjusted depending antibiotic sensitivity
Antibiotics should be continued for 6 weeks

22. Sx Involves joint drainage and lavage
May be performed arthroscopically
Early joint mobilisation should be encouraged

24. Pott’s disease

25. Pott’s disease Pott's disease is tuberculous spondylitis
Well recognised in Egyptian mummies
Described by Percival Pott in 1779
Now rare in western countries
Still prevalent in the developing world

26. Pathology Usually occurs secondary to infection elsewhere
Due to a combination of osteomyelitis and arthritis
Often occurs at more than one vertebral level
Usually affects anterior part of vertebral body
More common in thoracic spine
Bone destruction lead to vertebral collapse and kyphosis
Spinal cord can be narrowed resulting in cord compression and neurological deficit

27. Clinical presentation
Back pain is the commonest symptom
Pain may be present for several months
Pain can be both spinal and radicular
50% patients have neurological signs at presentation
Most patients have some degree of kyphosis
Cold abscess may point in the groin

28. Ix Serum ESR is usually massively raised
Tuberculin skin test is usually positive
Plain x-rays may show
Lytic destruction of anterior vertebral body
Anterior vertebral collapse
Reactive sclerosis
Enlarged psoas shadow
CT or MRI provides information on disc space and neurological involvement
As allows CT guided biopsy to obtain microbiological and pathological specimens

30. Tx
Treatment involves both tuberculous chemotherapy and possible surgery
Nine months of combination chemotherapy should be used
This involves 3 or 4 drugs
Isoniazid and rifampicin should be given for full nine months
Pyrazinamide, ethambutol or streptomycin should be give for first 2 months
Surgery is indicated if:
Neurological deficit
Spinal deformity with instability
No response to medical treatment
Non-diagnostic percutaneous biopsy
Surgical approach depends on extent of disease and level of spinal involvement
Usually involves radical debridement and posterior stabilisation