ortho - diseases of bone & joint (septic arthritis / osteomyelitis)

Question 1

osteomyelitis def

Answer 1

– inflammation of bone

Question 2

arthritis

Answer 2

– inflammation of a joint

Question 3

acute osteomyelitis

Answer 3

• Usually first decade of life
• More common in lower socio-economic groups
• Immune compromise – diabetes, renal disease, HIV
• More common in boys
• Mortality decreased from 50% to less than 1% with antimicrobial therapy

Question 4

acute osteomyelitis pathogenesis

Answer 4

1. metaphysis
   – Venous sinusoids
   – Slow blood flow
   – No cell lining: no capacity to phagocytose
   – Vulnerable to minor trauma
2. Transient bacteraemia
   – Skin, concurrent infection, teeth
   = Colonization
3. Oedema
   – ↑ tissue tension
   – Small infarcts (death of bone)
4. Pus
   – General circulation → Septicaemia
   – Medullary cavity → Full length of bone
   – Under periosteum → Strips periosteum, ↓periosteal blood supply → further infarction
   – Soft tissues → Abscess

Question 5

bacteriology acute osteomyelitis

Answer 5

1) Staph aureus – commonest in all age groups
2) Streptococcus–immunecompromised
3) Haemophilusinfluenza–infants
4) Gram –ve coliforms – neonates
5) Others

Question 6

acute osteomyelitis clinical features

Answer 6

• History of trauma
• Pain
• Fever
• Limp, reluctance to bear weight
• Pseudo-paralysis
• Metaphyseal tenderness
• Neighbouring joint swollen, not tense
• Late: Oedema, cellulitis, fluctuation
• Dehydration, ↓consciousness

Question 7

acute osteomyelitis lab investigations

Answer 7

• WCC ↑
• ESR ↑
• CRP ↑
• Blood cultures
• HIV
• U+E

Question 8

acute osteomyelitis x-ray investigations

Answer 8

• Initially normal (<10 days)
• Later: Soft tissue swelling, & Periosteal reaction
• Useful to exclude fracture
• Role of bone scan

Question 9

acute osteomyelitis management

Answer 9

1) Identify organism–blood cultures
2) Resuscitate / correct hydration – ivi fluids
3) Intravenous antibiotics–
* Cloxacillin – all ages
* Ampicillin – infants
* Gentamycin – neonates
* Modify according to culture results
4) Surgical drainage & decompression of bone
5) Splintage and analgesia
6) Oral antibiotics x 6 weeks

Question 10

acute osteomyelitis complications

Answer 10

1) Chronic osteomyelitis
2) Growth plate damage→ limb length discrepancy or angular deformity

Question 11

chronic osteomyelitis pathology

Answer 11

• Usually a sequel to acute osteomyelitis
• Extensive ischaemia in the acute stage:
  – Dead bone → Sequestrum
  – New bone → Involucrum
• Chronic sinuses
• Flare-up of acute infection / abscess

Question 12

chronic osteomyelitis x-ray

Answer 12

• Thickened bone, loss of normal architecture
• Areas of sclerosis and translucency – moth-eaten appearance
• Sequestrum
• Involucrum

Question 13

chronic osteomyelitis rx

Answer 13

• Debridement and sequestrectomy
• Lautenbach irrigation – system of tubes laid within bone to instill correct antibiotic directly to bone
• ? Bone graft

Question 14

chronic osteomyelitis complications

Answer 14

• Extensive ischaemia → no new bone formation
• Pathologic fractures with non union
• Flare-up of acute infection, abscess
• Growth disturbance
• Difficult to eradicate

Question 15

acute septic arthritis pathology

Answer 15

• Infection from: blood stream or 2° from adjacent bone
• Synovitis → fluid rich in polymorphs in joint
• Proteolytic enzymes → destruction of cartilage

Question 16

acute septic arthritis clinical features

Answer 16

• Pain
• Limp
• Pyrexia
• Tense swelling of joint
• ↓↓↓Movement of joint (protective muscle spasm)

Question 17

acute septic arthritis x-ray

Answer 17

• Widened joint space (sometimes)
• Exclude fracture

Question 18

acute septic arthritis differential diagnosis

Answer 18

RATTTHO

• Trauma
• Tumour
• Tuberculosis
• Acute rheumatic fever
• Rheumatoid arthritis
• Osteomyelitis
• Haemarthrosis / haemophilia

Question 19

acute septic arthritis rx

Answer 19

• Same as acute osteomyelitis but with arthrotomy
• Splintage to prevent contracture
• Physio to rehabilitate joint

Question 20

tuberculosis pathology

Answer 20

• Primary complex – lung or gut
• Secondary spread – with ↓ resistance
• Tertiary lesion – eg in bone or joint
• Giant cells coalesce → destruction of normal tissue and formation of caseous material

Question 21

TB general clinical feutures

Answer 21

• Gradual onset
• Lassitude, ↓ appetite
• Night sweats
• Loss of weight

Question 22

joint TB clinical features

Answer 22

• Pain, swelling, limp – gradual onset
• Synovial thickening, effusion, warm joint
• ↓ Movement

Question 23

joint TB x-ray

Answer 23

• Rarefaction of bone
• Erosion of cartilage
• Joint space narrowing

Question 24

joint TB rx

Answer 24

• TB drugs – INH, Rifampicin, PZA for 9 months
• Treat complications
• Fibrous ankylosis Deformity, Contractures
  = Osteotomies, arthrodeseis

Question 25

TB spine pathology

Answer 25

• Bacilli settle in vertebral body
• Vertebral body collapses
  ►Kyphosis
  ►Caseous material or bone compresses cord
  ►Neurology

Question 26

TB spine clinical features

Answer 26

• Back pain
• Lump (kyphos or gibbus)
• Neurology- paraesthesias, weakness, paraplegia

Question 27

TB spine x-ray

Answer 27

• Destruction of vertebral body
• Narrowed disc space
• Paravertebral abscess

Question 28

TB spine rx

Answer 28

1) Eradicate disease:
TB drugs
+/- Surgical debridement

2) Prevent or correct deformity:
Bracing
Spinal fusion

3) Prevent paraplegia

Question 29

TB spine early onset paresis

Answer 29

• 80% recover
• Due to abscess or bone sequestrum

Question 30

TB spine late onset paresis

Answer 30

• Due to: ↑Deformity, Re-activation & Cord ischaemia
• Prognosis less favourable