Perthes Disease

Question 1

pathogenesis

Answer 1

Osteochondritis of the femoral head
femoral head transiently loses its blood supply
Necrosis
Subsequent abnormal growth
Femoral head may collapse/fracture
Subsequent remodelling – how shape of femoral head & congruence of joint is determined by age of onset (older children faring worse) & the amount of collapse
incongruent joint to early onset arthritis

Question 2

who gets it?

Answer 2

idiopathic
4-9 yrs
boys more than girls - very active boys
short stature

Question 3

how is it investigated?

Answer 3

Pain
Limp
mostly unilateral
if bilateral– underlying skeletal dysplasia or thrombophilia
Loss of internal rotation – usually first clinical sign
Loss of abduction
Trendellenburg test positive – gluteal weakness
o lever arm of the abductor muscles is altered – weakness!

Question 4

how is investigated?

Answer 4

regular X-ray observation

Question 5

how is it managed?

Answer 5

regular x-ray ovbservation
avoidance of physical activity
50% do well
sometimes femoral head becomes aspherical, flattened, widened
severe cases – hip replacement in adolescence/ early adulthood
if femoral head sublux (partially dislocate) – osteotomy of femur or acetabulum