At what angle of knee flexion does the greatest strain on the ACL occur in an open kinetic chain?

At what angle of knee flexion does the greatest strain on the ACL occur in an open kinetic chain?

• A. 0-10 degrees
• B. 10-30 degrees
• C. 30-60 degrees
• D. 60-90 degrees

Answer: (B)

The greatest strain on the anterior cruciate ligament (ACL) during an open kinetic chain occurs at 10-30 degrees of knee flexion due to the biomechanics of the knee joint and the forces acting on the ACL during that range of motion. In an open kinetic chain, the lower leg is free to move while the thigh remains stationary. When the knee is at 0-10 degrees of flexion, the strain on the ACL is relatively low because the primary load is focused on stabilizing the joint without excessive tension. As the knee flexes to 10-30 degrees, the quadriceps muscle exert more pull on the tibia, creating anterior shear forces that increase strain on the ACL. The anatomy of the ligament and its attachments also contribute to increased tension in this range as the configuration of the knee joint allows for more pronounced movements of the tibia relative to the femur. Once the knee flexion exceeds 30 degrees, the strain on the ACL begins to decrease as other stabilizing structures of the knee, such as the posterior cruciate ligament and other soft tissues, take on more load. Thus, the 10-30 degree range is critical for understanding ACL injury risks in open kinetic chain exercises and activities, as this is

The greatest strain on the anterior cruciate ligament (ACL) during an open kinetic chain occurs at 10-30 degrees of knee flexion due to the biomechanics of the knee joint and the forces acting on the ACL during that range of motion.

In an open kinetic chain, the lower leg is free to move while the thigh remains stationary. When the knee is at 0-10 degrees of flexion, the strain on the ACL is relatively low because the primary load is focused on stabilizing the joint without excessive tension. As the knee flexes to 10-30 degrees, the quadriceps muscle exert more pull on the tibia, creating anterior shear forces that increase strain on the ACL. The anatomy of the ligament and its attachments also contribute to increased tension in this range as the configuration of the knee joint allows for more pronounced movements of the tibia relative to the femur.

Once the knee flexion exceeds 30 degrees, the strain on the ACL begins to decrease as other stabilizing structures of the knee, such as the posterior cruciate ligament and other soft tissues, take on more load. Thus, the 10-30 degree range is critical for understanding ACL injury risks in open kinetic chain exercises and activities, as this is