TRAUMATIC HIP DISLOCATION - EARLY MRI FINDINGS

Purpose. Objective of this study was to present the spectrum of early magnetic resonance imaging (MRI) findings following traumatic dislocat ion of the femoral head, and to identify any associated injuries that may have therapeutic or prognostic significance and be better delineat ed by MRI than by conventional radiography. Patients and methods. Pros pective MRI of both hips was performed on 18 patients (14 male, 4 fema le; age range 14-54 years; average age 30.5 years) within 5 weeks of a traumatic femoral head dislocation. The interval between the time of injury and the imaging studies ranged from 2 to 35 days (average 13.2 days). Posterior dislocation was present in 14 patients and anterior d islocation in 4 patients. In the majority of cases, we performed axial T1, coronal T1, and coronal T2 (MPGR) sequences. Images were retrosp ectively evaluated by consensus of three radiologists for possible abn ormalities of the bone and cartilage, joint space, and soft tissues. B ecause all patients were treated with closed reduction, surgical corre lation was not obtained. Results. All patients had a joint effusion or hemarthrosis. Of the 14 patients with posterior dislocation, isolated femoral head contusions (trabecular microfractures) were identified i n 6 patients. Four patients had small femoral head fractures, and one had an osteochondral defect. Acetabular lip fractures were seen in six patients, and one patient had a labral tear. Four patients had intra- articular loose bodies and one had ligamentum teres entrapment. Twelve patients had iliofemoral ligament injury. All patients had muscle inj ury involving the gluteal region and medial fascial compartment, and 1 3 patients had anterior fascial compartment muscle injury. Seven patie nts with posterior dislocation had posterior fascial compartment injur y. Of the four patients with anterior dislocation, two had bony contus ion, two had cortical infraction, one had a labral tear, and all four had an iliofemoral ligament injury. All four patients in this group ha d muscle injury of the gluteal region and of the anterior and medial f ascial compartments.