Traumatic hip dislocation with spontaneous incomplete reduction: a diagnostic trap.

We are reporting three children and adolescents who presented with incongruous reduction of the hip following injury. In each case, the diagnosis was initially missed. None of the patients presented with a hip dislocation, but two gave a history consistent with transient hip subluxation or dislocation. Low-energy trauma was the cause in two cases. Treatment consisted of arthrotomy to remove interposed capsule and labrum to obtain concentric reduction. When reduction of a hip dislocation occurs spontaneously, the condition may be misjudged. Any child or adolescent who complains of hip pain following injury should have radiographs scrutinized for asymmetric widening of the hip joints. Any asymmetry should be evaluated by appropriate imaging techniques such as computed tomography (CT) or magnetic resonance imaging (MRI). Removal of any interposed tissue is recommended, even when the diagnosis is delayed by several months.