The present study was conducted to evaluate the femoral and tibial tunnel positions created by the transtibial and outside-in techniques, and to assess the difference in clinical outcome between the two techniques after anterior cruciate ligament (ACL) reconstruction.
The study included 45 patients who underwent ACL reconstruction using either the transtibial (n=15) or outside-in (n=30) technique. Computed tomography scans of the treated knees were performed two weeks after surgery, and three-dimensional surface models were then produced. The positions of the femoral tunnels were measured by the quadrant method. Tibial tunnel aperture centers were measured in the anterior-to-posterior and medial-to-lateral directions on the tibial plateau.
The clinical outcomes were measured in terms of range of motion, the Lachman test, pivot shift test, KT-2000 arthrometry, and Lysholm score at 6 months after surgery.
On the femoral side, outside-in technique can create tunnels more accurately at the anatomic ACL footprint center than the transtibial technique.
On the tibial side, the bone tunnel positions for the transtibial and outside-in techniques were both significantly closer to the tunnel position that was indicated by data from previous studies.
There were no significant differences between the two groups in any of the physical parameters determined, or the Lysholm score.
The outside-in technique showed more accurate positioning of the femoral tunnels than the transtibial technique. It was difficult to create two femoral tunnels using the transtibial technique because the positions of the femoral tunnels are defined by the direction of the tibial tunnel. The present findings suggest that the outside-in technique is useful because it can create accurate positioning of the femoral tunnels independently.