The extensor mechanism of the knee joint: an anatomical study

This study investigated the anatomy of the structures that form the extensor mechanism of the knee joint using microsurgical techniques. Ten fresh-frozen human adult cadaveric knees were used. The quadriceps components, the infrapatellar tendon, the patellofemoral ligaments, and their relations to the neighboring anatomical structures were measured. The angles of the vastus lateralis and the vastus medialis muscle fibers to the rectus tendon were 26.6 and 41.1 degrees , respectively. The medial patellofemoral ligament connecting the femoral medial epicondyle to the medial edge of the patella was approximately 54.2 mm long, and its width ranged from 9 to 30 mm. The medial patellomeniscal ligament had a wide attachment to the meniscus whereas the attachment to the patella was narrow. The patellar tendon was 31.9 mm broad at its attachment to the apex of the patella and 27.4 mm wide at its attachment to the tibial tubercle. It was 38-49 mm long. Using the surgical microscope we were able to dissect and identify a trilaminar arrangement of prepatellar fibrous soft tissues. Also, we were able to identify the vessels and nerves around the patella. Details of clinical relevance and the possible pathological implications of the material presented are discussed. Emphasis is placed on the stability of the patellofemoral joint and the complex interaction between a range of factors providing it.