Biomechanical and Anatomical Effects of an External Rotational Torque Applied to the Knee: A Cadaveric Study

Background External rotational torque is one of the mechanisms that may occur during a pivoting or twisting injury to the knee. Hypothesis Simulated external rotational injury by applying external rotational torque will increase knee laxity and cause soft tissue damage to the knee. Study Design Controlled laboratory study. Methods Six cadaveric knees and a custom testing system were used to produce external rotational torque of 30°, 45°, and 60° with the knee at 30° of flexion. Anterior-posterior, valgus-varus, and rotational knee laxity were quantified. After sequential rotational torque to 60°, the specimens were dissected to identify injured structures. Results External rotational torque of 45° and 60° significantly increased knee joint laxity in all directions (P