- self limiting hip disorder caused by a varying degree of ischemia and subsequent necrosis of the femoral head;
- avascular necrosis of nucleus of proximal femoral epiphysis, abnormal growth of the physis, and eventual remodeling of regenerated
bone are the key features of this disorder;
- loss of blood supply to the epiphysis is thought to be the essential lesion;
- usually seen in 4 to 8 yr old boy with delayed skeletal maturity;
- male to female ratio: 4-5 to 1;
- rare in blacks;
- increased incidence with a positive family history, low birth wt, and abnormal pregnancy / delivery;
- upto 12% of cases are bilateral but will be at different stages & are asymmetric (vs. MED)
- ageis the key to the prognosis - after 8 yr represents poor prognosis;
- Clinical Presentation:
- includes pain (often knee pain) effusion (from synovitis) & a limp;
- early phase:
- limited abduction of hip & limited internal rotation in both flexion & extension are seen;
- antalgic gait (due to pain);
- late phase: Trendelenburg gait;
- Long Term Consequences:
- coxa magna
- coxa plana
- coxa breva
- hinged abduction:
- occurs when an enlarged femoral head is laterally extruded and impinges against the
acetabular rim when the hip is abducted;
此症常發於四至八歲之間的男孩子.
症狀之出現為漸進性.病童有疼痛、跛行現象,沒有全身症狀.患側髖部活動受制.
照骨盤X光時.即可見到股骨頭變形、崩壞、移位現象.而髖臼本身在初期還是好好的.這足以與結核病或其他疾病區別.
因為此症的原因並不清楚,所以也沒有好的預防方法.
治療須按病人發病年齡、現在年齡、壞死程度、是否有半脫位、關節活動度等來作決定.
若病人年齡小於六歲.壞死小於一半時.多半不需治療.但若壞死超過一半.且有半脫位現象時.則需考慮外張支架治療.
發病年齡大於七歲.壞死超過一半.有半脫位現象時.最好以手術治療.可以得到較佳的結果.
不管何種治療.其目標都希望股骨頭在癒合的過程中得到保護.不致變形.若變形或半脫位.將來都容易發生關節炎.