Anterior hip dislocations have been reported to account for approximately 5% to 10% of all hip dislocations.1 Epstein and Wiss2 originally divided anterior hip dislocations into superior (type I, including pubic or subspinous) and inferior (type II, including obturator and perineal) dislocations. This classification was further subdivided based on the presence of either no associated fracture (type A), fracture of the femoral head or neck (FNF; type B), or fracture of the acetabulum (type C).3 Of all anterior hip dislocations, it has been reported that the inferior or obturator type of dislocation is more common, constituting approximately 70% of all anterior dislocations.4 In 1943, Pringle5 described the mechanism of obturator dislocation as simultaneous abduction, flexion, and external rotation of the hip. Our literature search found only 2 case reports in non-English-language journals of a complete FNF associated with an attempted reduction of an anterior hip dislocation.6,7 Indentation fractures of the femoral head have been more commonly reported than FNFs, with a reported incidence of 35% to 55% after anterior dislocation.4,8 DeLee and colleagues8 also found that those patients with indentation fractures were at a higher risk for developing avascular necrosis of the femoral head in addition to being more likely to report poor or fair function of the hip 2 years after reduction.
There have been a number of different reduction maneuvers for anterior dislocation of hips published in the literature. Epstein and Harvey9 advocated reduction by traction in the line of the femur with the hip flexed and in gentle internal rotation and abduction while the patient was under general anesthesia. Toms and Williams,10 however, recommended adduction with gradual release of the longitudinal traction. Polesky and Polesky11 described a reduction method involving sharp internal rotation, which was found to be associated with FNF. The patient provided written informed consent for print and electronic publication of this case report, and approval was obtained from the Emory University Institutional Review Board.
The patient was a 73-year-old woman, an independent ambulator with minimal antecedent hip pain, who, as a pedestrian, was struck by a heavy-duty pickup truck at low velocity. She was flown to our level I trauma center from an outside hospital. The patient arrived hemodynamically stable, with a Glasgow Coma Scale score of 15 and with major complaints of right shoulder and right hip pain. She had a positive Focused Assessment with Sonography for Trauma (FAST), and underwent a subsequent urgent chest, abdomen, and pelvis computed tomography (CT) scan for further investigation. CT showed a grade 1 liver laceration. Her anteroposterior (AP) pelvic radiograph and pelvic CT scan showed an anterior hip dislocation with the femoral head located adjacent to the obturator foramen (Figures 1, 2). The AP pelvic radiograph and pelvic CT scan were scrutinized extensively before reduction to rule out a possible FNF. Comparing the right and left femoral necks through multiple axial CT images showed no obvious differences between the 2 sides (Figures 3, 4). Her only other orthopedic injury was an inferior shoulder dislocation. It is not routine for the general surgery trauma team to obtain a pelvic CT scan prior to involvement of the orthopedic service and prompt reduction of a hip dislocation. Upon initial examination of her right hip, it was fixed in slight flexion and external rotation; she was neurovascularly intact.
After being cleared by the trauma service, the patient provided informed consent for closed reduction of the hip and shoulder under conscious sedation, performed by the emergency department (ED) staff. She received intravenous fentanyl and midazolam, and the reduction was attempted. The reduction maneuver was performed with gentle inline traction, adduction, and internal rotation and extension. There was an audible clunk, and the hip was thought to be reduced and stable. The right leg lower extremity was placed into a knee immobilizer and she remained neurovascularly intact. The shoulder was reduced. After the procedure, the patient had an episode of hypoxia requiring oxygenation via a bag valve mask by the ED staff. Postreduction radiographs confirmed reduction of the right shoulder; however, they also showed a FNF with the femoral head retained near the obturator foramen (Figures 5, 6). The patient and her family were informed of the fracture, and a total hip arthroplasty (THA) was recommended, given her pre-injury mild symptomatic osteoarthritis in the hip and her age. The patient was admitted to the intensive care unit for cardiopulmonary monitoring and was found to have a troponin leak on hospital day 1. She was evaluated by the cardiology service; serial electrocardiograms and troponins ruled out acute myocardial infarction. The patient was cleared for surgery on hospital day 4.