Stressing on the human femoro-patellar joint. I. Components of a vertical and horizontal tensile bracing system.

Horizontal and vertical tensions act on the femoropatellar joint. In both knee joints of 60 human corpses the muscles and ligaments participating in the tensile bracing of the knee joint were studied macroscopically. While the structures acting in the vertical direction are very constant, the components participating in horizontal tensile bracing show large variations. Components of vertical tensile bracing are the quadriceps femoris muscle, the ligamentum patellae as well as the vertical patellar retinacula. The active part of horizontal tensile bracing consists of the medial and lateral vastus muscles. The passive components of this system are arranged in three layers. The superficial layer is formed by the fascia lata. The middle layer consists of the horizontal retinacula. A medial horizontal retinaculum was present in one third of our cases. It passes from the medial margin of the patella towards the medial femoral epicondyle. A lateral horizontal retinaculum is demonstrable in all cases studied. It passes horizontally from the lateral margin of the patella and inserts into the deep layer of the iliotibial tract. Insertion of the lateral horizontal retinaculum into the lateral femoral epicondyle was not observed in our material. The third layer is formed by ligaments supporting the joint capsule. These originate from the medial and lateral margin of the patella and pass towards their respective meniscus as well as variably towards the femoral or tibial condyle. These structures are found both medially and laterally in two thirds of the cases studied.