Tunnel Enlargement After Anterior Cruciate Ligament Reconstruction:Comparison Between Transtibial And Anteromedial Portal Techniques

Objective The aims of this study were to compare the tunnel enlargement between transtibial and anteromedial portal techniques after single-bundle anterior cruciate ligament (ACL) reconstruction.using postoperative magnetic resonance imaging (MRI) and the clinical results.Methods Between October2007and February2010,60consecutive patients, followed by an arthroscopically assisted ACL reconstruction with either an AM technique or TT technique, were enrolled in this study. The patients were divided into two groups:AM group (28patients) and the TT group (32patients). All the patients including both groups in this study underwent postoperative MRI and clinical evaluation (Lysholm score and Lachman test). The diameter was measured perpendicular to the axis of the tunnel at proximal, middle, and distal. Tunnel enlargement was determined by comparing the diameter of the tunnel on the radiograph obtained after about24months and the radiograph obtained instantly after the operation.Results Postoperatively Lysholm score were87.8±2.9in the AM group and83.5±2.8in the TT group after six months(P=0.048), and the Lachman test was significantly different from each other after two years (P=0.023) with a better outcome in AM group. On lateral radiographs, the TT group has a higher rate of tunnel enlargement, Al (30.8%v21.5%p=0.006), A2(25.6%v18.5%p=0.009), B1(22.8%v19.5%p=0.043), B2(22.6%v18.2%p=0.035),B3(22.3%v18.0%p=0.041), and there is no difference at the point of A3between TT group and AM group.Conclusion Drilling the femoral tunnel through the anteromedial arthroscopy portal rather than using a transtibial drilling technique diminishes the enlargement of bone tunnel and provides better clinical outcomes in the early phase after operation.