Summary

The first long-term follow-up of patients treated with contemporary ACL primary repair demonstrated acceptable rates of failure and reoperation, excellent PROMs and knee laxity, as well as no patients with clinically relevant PTOA at a minimum 10-year follow-up.

Abstract

Introduction

The resurgence of interest in preserving the anterior cruciate ligament (ACL) has led to an increasing number of studies reporting outcomes for ACL primary repair (ACLPR) at short- to mid-term follow-ups. This renewed interest is driven by the less invasive nature of contemporary ACLPR techniques and the high rates of posttraumatic osteoarthritis (PTOA) following ACL reconstruction, with up to 50% of patients undergoing ACLR developing PTOA. However, it remains uncertain whether the promising outcomes of contemporary ACLPR can be sustained in the long term, given that historic techniques have shown high failure rates over extended follow-up periods. Additionally, the proportion of patients undergoing ACLPR who develop subsequent PTOA remains unknown.
The objective of this study was to evaluate survival rates as well as clinical and radiological outcome parameter of ACLPR at a minimum 10-year follow-up to determine if the previously reported rates at short to mid-term follow-up can be sustained.

Methods

This retrospective analysis of the first 16 consecutive patients with proximal ACL tears undergoing ACLPR with dual suture anchor fixation by a single surgeon, spanned from 2008 to 2013. The indication for ACLPR was determined intra-operatively. Patients with a proximal type I tear and good to excellent tissue quality were eligible for ACLPR. Patients were considered for inclusion, if they had a minimum of 10-year follow-up data available. Primary outcomes included failure and re-operation rates. Secondary outcomes comprised patient-reported outcome measurements (PROMs; International Knee Documentation Committee (IKDC) subjective score, Lysholm score, Forgotten Joint Score (FJS), and Anterior Cruciate Ligament Return to Sport after Injury (ACL-RSI) score, and pre- to post-operative Tegner Activity Scale Difference). To assess clinical knee laxity anterior-tibial translational side-to-side difference (ATT SSD) was measured. The rate of asymptomatic and symptomatic PTOA (≥Grade 2 Kellgren & Lawrence) was evaluated independently by two observers on two plane x-rays obtained at minimum 10-year follow-up.

Results

Outcomes for 16 patients (mean ± SD (range), 38.2 ±11 (21-57) years of age) were recorded at final follow-up (mean± SD, 11.6 ±2 (10-16) years). Two patients (12.5%) were lost to follow-up, with 1 patient being unreachable and 1 patient declining further evaluation. At minimum 10-year follow-up two patients reported a traumatic ipsilateral ACL reinjury (12.5%), while two patients had to undergo reoperation (12.5%), with one patient undergoing meniscal repair and one patient contralateral ACL surgery. PROMs at the final follow-up demonstrated excellent outcomes and no significant differences when compared to results at 2- and 5-year follow-ups (IKDC, 94.5 ±7, p=0.718; Lysholm 93.8±11, p=0.410; Tegner difference -0.5 ±2, p=0.274). The FJS and ACL-RSI score were only assessed at final 10-yearfollow-up and demonstrated good to excellent results, with 91.3 ±15 and 79.3 ±28, respectively. ATT SSD was presented with 0.9 ±1mm, with no patients exceeding >3mm ATT SSD. No patient reported signs of symptomatic PTOA. At 10-years, 40% had KL grade 0 and 60% had grade 1, whereas no patients had grade 2 or higher. This was similar to preoperative (62.5% grade 0, 37.5% grade 1; p= 0.6) and to contralateral radiographs (37.5% grade 0, 50% grade 1, 12.5% grade 2; p= 0.6).

Conclusions

The first long-term follow-up of patients treated with contemporary ACLPR demonstrated acceptable rates of failure and reoperation, excellent PROMs and knee laxity, as well as no patients with clinically relevant PTOA at a minimum 10-year follow-up.