Tunnel expansion after anterior cruciate ligament reconstruction with autogenous hamstrings: A comparison of the medial portal and transtibial techniques

Purpose: The purpose of this study was to evaluate the effects of 2 techniques of drilling the femoral tunnel in anterior cruciate ligament (ACL) reconstruction (medial portal v transtibial) on tunnel expansion. Methods: Autogenous hamstring ACL reconstructions performed by the senior author between July 1998 and July 2004, with a minimum 6-month radiographic follow-up, using the transtibial technique (41 patients) and the medial portal technique (34 patients), were evaluated. All procedures were performed via an endoscopic technique with identical postoperative rehabilitation and graft fixation. Lateral and 45 degrees posteroanterior (PA) radiographs were obtained for each patient at a minimum of 6 months postoperatively. The sclerotic margins of the femoral and tibial tunnels were measured at the widest dimension of the tunnel by 2 physicians and were compared with the initially drilled tunnel size after correction for radiographic magnification. Statistical analysis was performed to compare the 2 groups by use of the independent-samples t test, with significance set at .05. Results: The mean percentage increase in the femoral tunnel was 38.20% +/- 17.76% for the medial portal technique and 53.96% +/- 21.72% for the transtibial technique on the PA view and 23.80% +/- 16.50% for the medial portal technique and 50.07% +/- 26.98% for the transtibial technique on the lateral view. This difference was statistically significant on both PA and lateral views. The mean percentage increase in the tibial tunnel was 31.81% +/- 14.39% for the medial portal technique and 36.31% +/- 17.81% for the transtibial technique on the PA view and 27.70% +/- 15.25% for the medial portal technique and 30.11% +/- 18.98% for the transtibial technique on the lateral view; however, these increases failed to reach statistical significance on either view. Conclusions: Femoral tunnel expansion for hamstring autologous ACL reconstructions is significantly lower for the medial portal technique when compared with the conventional transtibial technique. Level of Evidence: Level III, retrospective, comparative therapeutic study.