• M Lengsfeld.
• Klinik und Poliklinik für Unfallchirurgie, Johannes Gutenberg-Universität Mainz.
• Unfallchirurg. 1990 Sep 1; 93 (9): 412-7.

AbstractPatellofemoral loads are calculated by means of a mathematical model based upon an elliptical approximation of the articulating profile. Differences in the sagittal curvature of morphological and arthroplastic gliding surfaces can be approximated by a differing eccentricity of the ellipse. The joint is balanced in a static situation by two tension forces. The resultant is the vector sum of both forces and represents the entire load. Small loads in the initial flexion of the knee joint and high loads in the end of flexion are caused by a flat sagittal curve. A more eccentric shape of the articulating profile reduces the loads at the end of flexion, because the quadriceps tendon starts to turn around the femur earlier. The model also takes into account the patellar ligament turning around the proximal tibia at wide flexion angles. Besides the design of the prosthesis, patellofemoral loads depend on the height of implantation of the femoral component. It must be borne in mind that forces will vary in magnitude at different flexion angles; the patient's activities after the operation must also be considered.

17 keywords...

hide…