Bader R, Scholz R, Steinhauser E, Busch R, Mittelmeier W
Klinik für Orthopädie und Sportorthopädie, Technische Universität München.
Biomed Tech (Berl). 2004 May;49(5):137-44. doi: 10.1515/BMT.2004.027.
Dislocation of the artificial joint is a serious complication of total hip replacement. Various factors with an influence on dislocation stability were determined clinically. Our goal was to develop a method for evaluating experimentally the parameters implant design, position and the load situation for their influence on joint stability. With the newly developed testing device the range of motion to impingement and to dislocation can be determined at different implant positions. In addition, the rotational moments on subluxation, i.e. the "levering out" of the femoral head, can be determined. By way of example several hip implants were examined during movements associated with dislocation, e.g. (internal-)rotation in 90 degrees flexion and 0 degrees adduction as well as with (external-)rotation in combination with 10 degrees extension and 15 degrees adduction. Irrespective of implant design and position, the following movement phases can be differentiated: undisturbed motion, impingement, subluxation and, finally, complete dislocation of the head. On the basis of the range of motion of the specific phases, the moments occurring and the direction of dislocation, different implant systems can be compared. In this study the influence of the head diameter on the dislocation stability of the hip endoprosthesis is shown. With the aid of the model presented herein, a data set showing the most favourable and/or most dislocation stable implant position can be acquired for different combinations of the implant components. Additionally, useful information for implant design can be deduced and applied to new developments and/or modifications of existing implant components.
人工关节脱位是全髋关节置换术的一种严重并发症。临床上确定了影响脱位稳定性的各种因素。我们的目标是开发一种实验方法，以评估植入物设计、位置和负荷情况等参数对关节稳定性的影响。使用新开发的测试装置，可以在不同的植入物位置确定撞击和脱位时的运动范围。此外，还可以确定半脱位时的旋转力矩，即股骨头的“撬出”力矩。例如，在与脱位相关的运动过程中，对几种髋关节植入物进行了检查，如在90度屈曲和0度内收时的（内）旋以及在10度伸展和15度内收时的（外）旋。无论植入物的设计和位置如何，都可以区分以下运动阶段：无干扰运动、撞击、半脱位，最后是股骨头完全脱位。根据特定阶段的运动范围、出现的力矩和脱位方向，可以比较不同的植入系统。本研究显示了股骨头直径对髋关节假体脱位稳定性的影响。借助本文提出的模型，可以获得一组数据，显示不同植入物组件组合下最有利和/或最抗脱位的植入物位置。此外，可以推导出对植入物设计有用的信息，并应用于现有植入物组件的新开发和/或修改。
