Protection of the medial femoral condyle articular cartilage during drilling of the femoral tunnel through the accessory medial portal in anatomic anterior cruciate ligament reconstruction.

Accurate positioning of the femoral tunnel in the native femoral anterior cruciate ligament (ACL) footprint requires drilling through an accessory medial portal (AMP). The AMP is located far medial and at a low level. Despite the benefits of drilling through the AMP, it is possible that the drill bit head will injure the articular cartilage of the medial femoral condyle as it slides along the guide pin to the femoral insertion of the ACL. Because more surgeons are now performing anatomic ACL reconstructions and shifting from transtibial drilling toward transportal drilling, the risk of this injury might be increasing, especially during the beginning of their learning curve. To avoid such injury, a bio-interference screw sheath is used. It is inserted through the AMP over the guide pin until it reaches near the medial wall of the lateral femoral condyle. The drill bit is inserted over the guide pin and through the bio-interference screw sheath. Using the bio-interference screw sheath not only protects the articular cartilage of the medial femoral condyle but also protects the medial meniscus, posterior cruciate ligament, and skin of the AMP from injury because of the close proximity of the drill bit head to these structures during transportal drilling.