No difference in revision rates between anteromedial portal and transtibial drilling of the femoral graft tunnel in primary anterior cruciate ligament reconstruction: early results from the New Zealand ACL Registry

Purpose The use of an accessory anteromedial portal to drill the femoral graft tunnel in primary anterior cruciate ligament (ACL) reconstruction was introduced in the 2000s in an effort to achieve a more anatomic femoral tunnel position. However, some early studies reported an increase in revision ACL reconstruction compared to the traditional transtibial technique. The aim of this study was to analyse recent data recorded by the New Zealand ACL Registry to compare outcomes of ACL reconstruction performed using the anteromedial portal and transtibial techniques. Methods Analysis was performed on primary isolated single-bundle ACL reconstructions recorded between 2014 and 2018 by the New Zealand ACL Registry. Patients were categorised into two groups according to whether an anteromedial portal or transtibial technique was used to drill the femoral graft tunnel. The primary outcome was revision ACL reconstruction and was compared between both groups through univariate and multivariate survival analyses. The secondary outcomes that were analysed included subscales of the Knee Injury and Osteoarthritis Outcome Score (KOOS) and Marx activity score. Results Six thousand one hundred and eighty-eight primary single-bundle ACL reconstructions were performed using either the anteromedial portal or transtibial drilling techniques. The mean time of follow-up was 23.3 (SD +/- 14.0) months. Similar patient characteristics such as mean age (29 years, SD +/- 11), sex (males = 58% versus 57%) and time to surgery (median 4 months, IQR 5) were observed between both groups. The rate of revision ACL reconstruction was 2.6% in the anteromedial portal group and 2.2% in the transtibial group (n.s.). The adjusted risk of revision ACL reconstruction was 1.07 (95% CI 0.62-1.84, n.s.). Patients in the anteromedial portal group reported improved scores for subscales of the KOOS and higher Marx activity scores at 1-year post-reconstruction. Conclusion There was no difference in the risk of revision ACL reconstruction between the two femoral tunnel drilling techniques at short-term follow-up. We observed minor differences in patient-reported outcomes at 1-year follow-up favouring the anteromedial portal technique, which may not be clinically relevant. Surgeons can achieve good clinical outcomes with either drilling technique.