Biomechanical Analysis After Chiari’s Pelvic Osteotomy by Means of Superimposed Pelvic Computed Tomography Scan
Changes in the bony and muscular structure of the pelvis after Chiari’s pelvic osteotomy were investigated in 18 hips (18 females patients) by means of pre- and postoperative computed tomography. After operation, the distance between the centers of the femoral heads decreased by an average of 0.7 cm and that between the anterior-superior iliac spines increased by an average of 1.1 cm. The iliac wing of the operated side was displaced laterally, but that of the non-operated side remained unchanged. Femoral head coverage improved from 53.3% to 88.1% postoperatively. On simulation, the direction of the vector of the gluteus medius and the resultant force changed vertically, from a preoperative value of 21.6° to 16.7° and from 14.9° to 11.1°, respectively, after operation. The resultant force on the femoral head decreased from a preoperative value of 3.42 W to 2.92 W after operation. In our method of Chiari’s osteotomy the inferior fragment was medialized, while the superior fragment was simultaneously displaced laterally; consequently biomechanical improvement was achieved.
KeywordsFemoral Head Resultant Force Acetabular Dysplasia Biomechanical Analysis Gluteus Medius
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