Simulated femoral repositioning with three-dimensional CT.

Three-dimensional volumetric rendering of CT data has proven to be valuable in the evaluation of the hip. Although video loop animation allows review of the anatomy from all perspectives, it does not show the functional range of motion of the femur in the acetabulum. We have developed a technique termed simulated dynamic CT that gives dynamic animated three-dimensional viewing capabilities. This technique incorporates static CT data with gait and movement data to produce a sequence of dynamic images simulating range of motion. Additionally, this technique allows simulation of surgical techniques to visually anticipate the results of reduction and traction and potential limitations in subsequent hip movement. To assess the potential of this technique, two dysplastic hip patients were studied prior to reconstruction. In each case the perspective thus gained led to altered surgical management.