Sports injury: biomechanical approach to interpretation of knee MRI

Sports-related knee injuries are common and clinically consequential. Interpreting MR imaging through a biomechanical lens links injury patterns to the forces that produced them, improving the detection of subtle but prognostically important lesions. Characteristic osseous findings-contusions, subchondral/osteochondral fractures, and avulsions-act as "maps" of force vectors that distinguish compression from distraction mechanisms. In anterior cruciate ligament (ACL) trauma, bone bruise locations have kinematic associations (i.e., valgus-flexion-external rotation vs varus-flexion-internal rotation) and enable a targeted search for injuries involving functionally related structures, such as the menisci. The medial meniscus functions as a secondary stabilizer to anterior tibial translation. Therefore, peripheral vertical longitudinal tears and meniscocapsular ramp lesions are frequent companions of ACL rupture and may be overlooked without a mechanism-based approach. The lateral meniscus is vulnerable to radial/posterior root and peripheral capsular injuries during translational and compressive loading of the lateral compartment. Posterolateral corner structures resist varus and external rotation forces; unrecognized PLC injury compromises cruciate reconstruction and perpetuates rotatory instability. This review synthesizes biomechanical principles to provide a practical, pathophysiological framework for MRI interpretation and reporting. Applying this approach enhances diagnostic accuracy, guides surgical decision-making, and supports better outcomes for athletes with acute knee trauma. KEY POINTS: • Biomechanical principles provide a systematic framework for interpreting knee MRI after sports trauma, improving diagnostic accuracy and detection of subtle lesions. • Characteristic injury patterns on MRI often reveal the underlying traumatic mechanism, directing targeted evaluation of osseous structures, ligaments, tendons, and menisci. • Subtle injuries such as Segond fracture, ramp lesion, or posterolateral corner disruption may be overlooked without a mechanism-based interpretive approach.