Planning and evaluation of reorienting osteotomies of the proximal femur in cases of SCFE using virtual three-dimensional models

Abstract

Slipped Capital Femoral Epiphysis (SCFE) is a disease affecting the geometry of adolescent hips. Evaluation of the slippage as well planning of correction surgeries is a major three-dimensional problem. Therefore, the current clinical approach, which is based on biplanar plain radiographs, is not satisfying. We have developed a software environment for planning and evaluation of reorienting osteotomies in severe cases of SCFE. In our system CT-based virtual surface models fitted by oriented bounding boxes (OBB) are manipulated. The hip motion as well as a correction surgery can be simulated. Both are controlled by collision detection. Therefore, the motion is based on the surface geometry of the joint partners rather than on a predefined, fixed rotation center. The pre-and simulated postoperative evaluation uses the range of motion as the essential parameter. The surgeon can obtain valuable information about the geometric correlation of the physiologic joint faces along hip motion.