Missed or developmental dislocation of the hip.

In 15 documented cases, subluxation or dislocation of the hip was discovered months or years after previous multiple normal physical examinations. The examiners were unique in that six were professors specializing in childrens' orthopedics, four were board-certified orthopedists, and five were pediatricians. An increased acetabular index, subluxation, and early dislocation may not always be detected on physical examination. Delayed diagnosis of dislocation is not evidence that an inadequate physical examination was performed. An increased acetabular index may allow the femoral head to move laterally out of the acetabulum and become a delayed dislocation. The delayed subluxed or dislocated hip constitutes an entity not necessarily related to the neonatal subluxable or dislocatable hip.