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To study the structural and functional properties of the human posterior cruciate ligament complex, we measured the cross-sectional shape and area of the anterior cruciate, posterior cruciate, and meniscofemoral ligaments in eight cadaveric knees. The posterior cruciate ligament increased in cross-sectional area from tibia to femur, and the anterior cruciate ligament area decreased from tibia to femur. The meniscofemoral ligaments did not change shape in their course from the lateral meniscus to their femoral insertions. The posterior cruciate ligament cross-sectional area was approximately 50% and 20% greater than that of the anterior cruciate ligament at the femur and tibia, respectively. The meniscofemoral ligaments averaged approximately 22% of the entire cross-sectional area of the posterior cruciate ligament. The insertion sites of the anterior and posterior cruciate ligaments were evaluated. The insertion sites of the anterior and posterior cruciate ligaments were 300% to 500% larger than the cross-section of their respective midsubstances. We determined, through transmission electron microscopy, fibril size within the anterior and posterior cruciate ligament complex from the femur to the tibia. The posterior cruciate ligament becomes increasingly larger from the tibial to the femoral insertions, and the anterior cruciate ligament becomes smaller toward the femoral insertion. We evaluated the biomechanical properties of the femur-posterior cruciate ligament-tibia complex using 14 additional human cadaveric knees. The posterior cruciate ligament was divided into two functional components: the anterolateral, which is taut in knee flexion, and the posteromedial, which is taut in knee extension. The anterolateral component had a significantly greater linear stiffness and ultimate load than both the posteromedial component and meniscofemoral ligaments. The anterolateral component and the meniscofemoral ligaments displayed similar elastic moduli, which were both significantly greater than that of the posteromedial component.

Determination of ligament forces is an integral part of understanding their contribution during motion and external loading of an intact joint. While almost all previous investigations have reported only the magnitude of tension, this alone cannot adequately describe the function of a particular ligament. An alternative approach to determine the in-situ forces in ligaments has been developed which utilizes a universal force-moment sensor in conjunction with a force transformation scheme. In addition to providing the magnitude of ligament force, the direction and point of application of this in-situ force can also be determined. Further, the approach does not require mechanical contact with the ligament. Application of this new methodology is demonstrated for the human anterior cruciate ligament in the present study (n = 7) although it may be similarly applied to other ligaments at the knee or in other synovial joints of the human body.

Osteochondrosis of the humeral capitellum can be successfully treated conservatively if treatment is begun in an early stage of the disease.

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