Evaluation of Location of Femoral and Tibial Tunnels after Arthroscopic Anterior Cruciate Ligament Reconstruction: A Longitudinal Study

Abstract

Introduction: Anterior Cruciate Ligament (ACL) is the most commonly injured ligament when knees are injured. The position of the bone tunnels, and therefore the graft, is an important factor for successful reconstruction and clinical results. An incorrect positioning may result in impingement of neoligament at roof of intercondylar notch, or impaction against Posterior Cruciate Ligament (PCL) or may cause abnormal tension on the graft and may cause clinical problems such as loss of range of motion and recurrent instability. Aim: To evaluate the location of tunnels and its impact on functional outcome in patients who underwent arthroscopic ACL reconstruction. Materials and Methods: In this prospective longitudinal cohort study at a tertiary healthcare centre, from December 2017 to November 2019. A total of 50 patients who had isolated ACL injury and had undergone arthroscopic ACL reconstruction with minimum one year follow up were included. Their postoperative radiographs were evaluated for femoral and tibial tunnels. International Knee Documentation Committee questionnaire (IKDC), Lysholm scoring, pivot shift and Lachman test were used for evaluating the functional outcome. Findings were summarised and t-test was used for evaluation of results. Results: There were 48 male and two female patients, 64% patients involving right side. Mean position of tibial tunnel in coronal plane was 45.48±2.55 mm from medial edge. Average tibial tunnel angle in coronal plane was 69.46±7.57 degrees with only one patient having tibial tunnel >80 degrees. Position of tibial tunnel in sagittal plane was 41.35±7.3 mm, eight patients with >50% posterior location of tibial tunnel from anterior edge. Average Coronal angle of femoral tunnel was 42.52±6.34 degree. Position of femoral tunnel along Blumensaat’s line from posterior edge of femoral cortex was 35.19±6.09 mm. Graft impingement was not found in any of the case intraoperatively nor postoperatively, as analysed on x-rays. Conclusion: The position of femoral and tibial tunnels is a very important indicator for good functional outcome postoperatively. Thus, there needs to be further research to exactly quantify the limits for tunnel position beyond which the outcome of ACL reconstruction will be definitely poor.