Osteomyelitis, Perthes + Discoid Meniscus

Question 1

What is Osteomyelitis?
What is the most common site?
Aetiology + RF?

Answer 1

1) Infection of the metaphysis of LONG BONES.
2) Distal site of femur, proximal tibia.
3) Due to haematogenous spread of the pathogen, but may arise due to direct spread from infection (Staph Aureus, group B strep, Haemophilus influenzae).

RF: Sickle cell anaemia (risk of staphylococcal or salmonella osteomyelitis)

Question 2

Presentation of Osteomyelitis?

Answer 2

1) Painful, immobile limb in a child with acute febrile illness: pain on movement.
2) Directly over the infected site there is swelling and tenderness (erythematous and warm).

Ddx: Metastatic bone cancer

Question 3

Diagnosis of Osteomyelitis?

Answer 3

1) Bone cultures
2) Raised WCC, ESR, CRP
3) MRI - identify infection in bone
4) Radionuclide bone scan - if site of infection unclear

Question 4

Treatment of Osteomyelitis?

Answer 4

1) Parenteral antibiotics for several weeks - IV Vancomycin (Staph) or IV Teikoplanin (Strep). Prevents bone necrosis, IV until clinical ft and acute-phase reactants return to normal, and oral therapy for several weeks after.
2) Surgical drainage if response to antibiotic therapy poor.
3) Limb initially rested in a split and subsequently mobilised.

Question 5

What is Perthes disease?

Answer 5

• Avascular necrosis of the femoral head due to interruption of the blood supply.
• More common in males, bilateral 10% of time, affects 5-10 yrs.
• Interruption of blood supply is followed by revascularisation and reossification over 18-36m.
• Bone remodelling results in distortion of epiphysis and generates abnormal reossification.

Question 6

Clinical presentation of Perthes? Ddx?

Answer 6

1) Onset of limb (hip or knee) pain.
2) All hip movements are limited (especially internal rotation and abduction).

Ddx: Transient synovitis

Question 7

Diagnosis of Perthes?

Answer 7

1) X-ray: Increased density in femoral head - becomes fragmented and irregular. Joint space widening is visible.
2) MRI and bone scan helpful.

Question 8

Treatment of Perthes?

Answer 8

Prognosis dependant on early diagnosis:

1) Early identification with less than half the femoral head affected: bed rest and traction sufficient.
2) In more severe cases/late presentations - femoral head needs to be covered by the acetabulum to act as mould for re-ossifying epiphysis (hip kept in abduction with plaster/callipers or pelvis/femoral osteotomy).

Question 9

Prognosis of Perthes?

Answer 9

1) Good in most children especially below 6yrs.
2) In older children - there can be more extensive involvement of epiphysis, metaphysis + bone deformity - potential for subsequent degenerative arthritis in adult life.

Question 10

Kohler disease Sx, Dx, Tx:

Answer 10

• Rare, transient avascular necrosis of the navicular bone.
• More common in males and 3-5 yrs.

Sx: Pain in mid-tarsal region causing limp.

Dx - X-ray shows dense, deformed bone.

Tx - Symptomatic- rest foot/walking plaster + analgesia (ibuprofen)

Question 11

What is discoid meniscus?

Answer 11

• Meniscus is soft piece of cartilage that acts as a shock absorber to protect the knee.
• 2 of these C-shaped pads in each knee (crescent shape).
• Discoid meniscus is thicker than normal and has a different shape/texture: more likely to be injured, during childhood?

Question 12

Ax and Presentation of discoid meniscus?

Answer 12

• Discoid meniscus injury often precipitated by twisting motions to the knee (pivoting motion or changes direction when playing sport).

Sx:

1) Pain, stiffness, swelling
2) Unable to fully straighten knee
3) Catching, popping, locking of the knee.

Question 13

Diagnosis and treatment of discoid meniscus?

Answer 13

Dx:

1) X-ray - space between femur and tibia can appear wide.
2) MRI - to see meniscus clearly (not visible well on X-ray)

Tx:
- Surgical repair of meniscus