Tunnel Position and Relationship to Postoperative Knee Laxity after Double-Bundle Anterior Cruciate Ligament Reconstruction with a Transtibial Technique

Abstract

Background Several laboratory studies have pointed out a potential risk of femoral tunnel misplacement in anterior cruciate ligament reconstruction with a transtibial technique. The tunnel malposition away from the anatomic attachment may result in increased postoperative knee laxity in double-bundle reconstruction. Purpose This study was conducted to evaluate the femoral and tibial tunnel positions in transtibial double-bundle reconstruction, and to determine the relationship between the tunnel positions and the results of the postoperative knee laxity examinations. Study Design Case series; Level of evidence, 4. Methods Fifty-three of 71 patients who underwent transtibial double-bundle reconstruction from 2004 to 2005 were followed more than 24 months. The tunnel positions for the anteromedial and posterolateral grafts were measured using 3-dimensional computed tomography images applying the quadrant method. The postoperative knee laxity was examined with the KT-1000 arthrometer manual maximum test, anterior drawer test, and pivot-shift test. Results The deep-shallow position (parallel to Blumensaat's line) and high-low position (perpendicular to Blumensaat's line) of the femoral tunnels were 27.7% ± 5.6% from the most posterior condylar contour and 16.3% ± 5.2% from Blumensaat's line for the anteromedial graft, and 35.5% ± 6.4% and 48.0% ± 5.4% for the posterolateral graft. The medial-lateral and anterior-posterior positions of the tibial tunnels were 46.1% ± 2.6% from the most medial contour and 36.5% ± 4.9% from the most anterior contour for the anteromedial graft, and 47.5% ± 3.1% and 51.6% ± 5.0% for the posterolateral graft. There was no statistical correlation between any parameters of the femoral or tibial tunnel position and the results of the knee laxity tests. Conclusion The femoral tunnels placed in transtibial double-bundle reconstruction were located appropriately in high-low and deep-shallow orientation, but had larger variability than the previously reported data of the anatomic femoral attachment. However, the variability of the femoral tunnel position was not so large as to result in graft insufficiency with increased postoperative knee laxity.