Missed Pediatric Traumatic Hip Dislocation: A Case Report.

Abstract

While traumatic hip dislocation is an uncommon injury in children, it is believed that urgent reduction within six hours of injury reduces the risk of osteonecrosis of the femoral head1. Mehlman et al. reported that there is a twentyfold increased risk of osteonecrosis, which becomes radiographically apparent within twelve months after dislocation, when reduction takes place more than six hours after injury2. Reduction should be performed with caution; adequate muscle relaxation is important because there is increased risk of femoral epiphysis displacement or epiphysiolysis without anesthesia3. Postreduction radiographs should be critically analyzed for concentric reduction since subtle incongruence often reflects entrapped soft tissue and the need for open reduction. Coxa magna is a common late radiographic finding that occurs more frequently in children younger than ten years old and is not associated with functional limitation; however, osteonecrosis and osteoarthritis have clinical sequelae4. In Barquet’s retrospective review of 145 cases of traumatic hip dislocations in children, 92% had radiographic evidence of osteonecrosis at the two-year follow-up5. He compared the presentation of osteonecrosis with Legg-Calve-Perthes disease even though the retrospective review of radiographs alone does not include the total time spent dislocated5. Table I provides details of Barquet’s radiograph-based osteonecrosis classification following pediatric traumatic hip dislocations5. Barquet reported three cases of neglected (>40 hours) hip dislocation with osteonecrosis of the femoral head at five, nineteen, and twenty months after injury6. Banskota et al. reported the follow-up of neglected (mean delay, twelve months) traumatic hip dislocations in eight children, all of whom were treated with open reduction; all had evidence of osteonecrosis at the time of follow-up (mean, seven years)7. Kumar and Jain reported neglected (mean delay, sixteen weeks) traumatic Epstein type-I hip dislocations, all …