Hehne H J
Department of Surgery, University of Freiburg, Federal Republic of Germany.
Clin Orthop Relat Res. 1990 Sep(258):73-85.
An analysis of the patellofemoral joint based on experimental determinations of pressure distributions on the patellar cartilage and vectorial calculations is presented. The extension torque of all quadriceps muscles is similar. The force transmitted to the patella by the retinacula is small in all knee positions. Because the rigid patella has its own lever arms and tendon insertions at different heights, the forces on patellar and quadriceps tendons are unequal. The small patellar contact areas change according to flexion and are dependent on quadriceps force. Retropatellar pressure is thereby limited and becomes independent of flexion angle. By virtue of the direct force transmission of the quadriceps tendon to the femur, the increase in the retropatellar force is strongly limited beyond 70 degrees. The lateral-to-medial ratio of contact areas, pressing forces, cartilage areas, and bone mass is always 1.6:1, whereas the mean pressure is the same on both facets. The osseous form of the patella does not allow identification of dysplasia because cartilage compensates for apparent incongruence, especially about the medial ridge. This permits the rigid patella to adapt itself to very different abutments. Its individual form results from functional adaptation and does not explain chondromalacia. The ventralization of the tibial tuberosity does not alter retropatellar loading. The mediodistal transfer results in a high increase of pressure on both facets.
本文基于对髌软骨压力分布的实验测定和矢量计算，对髌股关节进行了分析。所有股四头肌的伸展扭矩相似。在膝关节的所有位置，髌支持带传递至髌骨的力都很小。由于坚硬的髌骨有其自身不同高度的杠杆臂和肌腱附着点，髌腱和股四头肌腱上的力并不相等。较小的髌骨接触面积会随屈曲而变化，并取决于股四头肌的力量。因此，髌后压力受到限制，且与屈曲角度无关。由于股四头肌腱直接向股骨传递力，超过70度后髌后力的增加受到强烈限制。接触面积、压力、软骨面积和骨量的外侧与内侧比值始终为1.6:1，而两个小平面上的平均压力相同。髌骨的骨质形态无法识别发育异常，因为软骨可补偿明显的不匹配，尤其是在内侧嵴附近。这使得坚硬的髌骨能够适应非常不同的支撑结构。其个体形态源于功能适应，而非解释软骨软化的原因。胫骨结节腹侧化不会改变髌后负荷。向中远端转移会导致两个小平面上的压力大幅增加。
