Is computed tomography useful after simple posterior hip dislocation?

Recent articles and textbooks of orthopaedic traumatology recommend routine computed tomography (CT) scans after successful reduction of simple posterior hip dislocations. This is based on the belief that CT, even in cases with concentric reductions, may identify fractures or intraarticular loose bodies not apparent on standard radiographs. This study was conducted to assess the usefulness of CT after concentric reduction of simple posterior hip dislocations. The hospital database was searched for all traumatic hip dislocations in the past 4 years. Charts and radiographs were reviewed, and only patients with simple posterior hip dislocations (no acetabular or femoral head fractures) and a concentric reduction identified on plain radiographs were included. Twenty-three patients who met these criteria and had subsequent CT scans to evaluate the hip joint were identified. CT scans confirmed the concentric reduction in all patients. Three small occult fractures were identified, and no occult intraarticular loose bodies were found. CT findings did not alter the treatment plan for any of the patients studied. In this small group of patients, CT scanning was not useful after concentric reduction by plain radiography of simple posterior hip dislocations.