The Anterior Cruciate Ligament (ACL) in your knee can support the weight of a small car.

The Anterior Cruciate Ligament (ACL) is a critical stabilizer in the human knee joint. Biomechanical studies, such as those published in the Journal of Biomechanics, have measured the ultimate tensile strength of a healthy young ACL at approximately 2,160 Newtons. This translates to roughly 485 pounds of force before the tissue actually ruptures.The ligament is composed of Type I collagen fibers arranged in a complex, longitudinal weave. This biological architecture functions similarly to high-tensile steel cables or synthetic climbing ropes. This extreme strength is necessary because the knee must endure massive loads during athletic movements. For example, landing from a high jump can subject the joint to forces exceeding five times an individual's total body weight.Research from institutions like the Mayo Clinic highlights that while the ACL is incredibly strong, it is most vulnerable to rotational forces. Most tears occur during 'non-contact' events where a person pivots or decelerates too quickly. Even though it can hold the weight of a small vehicle, the specific angle of the force is what usually leads to injury. Modern orthopedic surgery has evolved to use autografts or allografts to replicate this incredible natural strength during reconstruction.