The radiograph shown in Figure A reveals a left hip dislocation, with some obscuring of detail secondary to the trauma backboard. CT scans should be obtained following a hip dislocation to evaluate for fractures or impacted areas of the femoral head or acetabulum, as well as noncongruent reductions and free intraarticular joint fragments.
The referenced study by Brumback et al comments on the importance of post-reduction CT scans and found that 23% of their posterior wall fractures had associated marginal impaction, with 94% of these discovered via preoperative CT scan.
Brumback RJ, Holt ES, McBride MS, Poka A, Bathon GH, Burgess AR. Acetabular depression fracture accompanying posterior fracture dislocation of the hip. J Orthop Trauma. 1990;4(1):42-8.
PMID:2313429 (Link to Abstract)