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Biomechanical and anatomical effects of an external rotational torque applied to the knee: a cadaveric study
Rick P Csintalan1, Amirhesam Ehsan, Michelle H McGarry
1Kaiser Permanente, Anaheim, CA, USA.
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 degrees , 45 degrees , and 60 degrees with the knee at 30 degrees of flexion. Anterior-posterior, valgus-varus, and rotational knee laxity were quantified. After sequential rotational torque to 60 degrees , the specimens were dissected to identify injured structures.
Results:
External rotational torque of 45 degrees and 60 degrees significantly increased knee joint laxity in all directions (P < .05). Dissection showed that all posterior cruciate ligaments were intact; all medial collateral and anterior cruciate ligaments revealed either partial or complete tears. The lateral collateral ligaments were torn in all specimens. The popliteus tendon was attenuated in 1 specimen and was completely torn in 1 specimen. The popliteofibular ligament was torn in 3 specimens.
Conclusion:
External rotational torque to 60 degrees increased knee laxity, and dissection revealed a consistent pattern of injury to the medial and lateral collateral and anterior cruciate ligaments and posterolateral corner.
Clinical Relevance:
Because isolated ligament injuries are rare, recognizing these combined ligamentous injuries early is essential for repair in the acute stage.
