Three-dimensional pressure distribution of the human hip joint--comparison between normal hips and dysplastic hips.

We developed a system for analyzing the three-dimensional contact pressure distribution in the human hip joint. Hip joint images obtained by computed tomography were loaded into a computer, and the articular surface was reconstructed as a three-dimensional polygonal model. The pressure distribution of this hip model was then analyzed using a rigid-body spring model. Using this system, the three-dimensional pressure distribution in dysplastic hips was compared with that in normal hips. Seven dysplastic hips and five normal hips were analyzed. In the dysplastic hips, the maximum peak pressure was 5.3 MPa, while it was 2.5 MPa in the normal hips. The peak pressure was located at the edge of the acetabulum in the dysplastic hips. This system allowed us to easily and accurately evaluate the mechanical status of the hip joint. For individual patients, the clinical course could be easily predicted and various treatment methods could be examined preoperatively.