Comparable Instrumented Knee Joint Laxity and Patient-Reported Outcomes After ACL Repair With Dynamic Intraligamentary Stabilization or ACL Reconstruction: 5-Year Results of a Randomized Controlled Trial

BACKGROUND: Technical innovation has led to the renaissance of anterior cruciate ligament (ACL) repair in the past decade. PURPOSE/HYPOTHESIS: The present study aimed to compare instrumented knee joint laxity and patient-reported outcomes (PROs) after ACL repair with those after primary ACL reconstruction for acute isolated ACL tears. It was hypothesized that ACL repair would lead to comparable knee joint stability and PROs at 5 years postoperatively in comparison with ACL reconstruction. STUDY DESIGN: Randomized controlled trial; Level of evidence, 1. METHODS: A total of 85 patients with acute ACL tears were randomized to undergo either ACL repair using dynamic intraligamentary stabilization (DIS) or primary ACL reconstruction with a semitendinosus tendon autograft. The primary outcome was the side-to-side difference in anterior tibial translation (ΔATT) assessed by Rolimeter testing at 5 years postoperatively. Follow-up examinations were performed at 1, 2, and 5 years. PROs were assessed using the Tegner activity scale, the International Knee Documentation Committee (IKDC) subjective score, and the Lysholm score. Furthermore, the rates of recurrent instability, other complications, and revision surgery were recorded. A power analysis was performed a priori, and the Friedman test, Mann-Whitney U test, and Bonferroni correction were applied for statistical comparisons with significance set at P < .05. RESULTS: The mean age at inclusion was 28.3 ± 11.5 years in the ACL repair group and 27.1 ± 11.5 years in the ACL reconstruction group. At 5 years postoperatively, a total of 64 patients (ACL repair: n = 34 of 43 [79%]; ACL reconstruction: n = 30 of 42 [71%]) were available for follow-up. At 5 years, ΔATT was 1.7 ± 1.6 mm in the ACL repair group and 1.4 ± 1.3 mm in the ACL reconstruction group (P = .334). Preinjury PROs were restored as soon as 1 year after surgery and plateaued until 2 and 5 years postoperatively in both groups. At the 5-year follow-up, the mean Lysholm score was 97.0 ± 5.4 versus 94.5 ± 5.5 (P = .322), respectively, and the mean IKDC subjective score was 94.1 ± 9.9 versus 89.9 ± 7.8 (P = .047), respectively, in the ACL repair group versus ACL reconstruction group. At 5 years postoperatively, 12 patients in the ACL repair group (35%; age <25 years: n = 10/12; Tegner score ≥7: n = 10/12) had recurrent instability, of whom 10 underwent single-stage revision ACL reconstruction. In the ACL reconstruction group, there were 6 patients with recurrent instability (20%; age <25 years: n = 6/6; Tegner score ≥7: n = 5/6); however, in 5 patients, staged revision was required. Differences between both groups regarding recurrent instability (P = .09) or ACL revision surgery (P = .118) were not statistically significant. Recurrent instability was associated with age <25 years and Tegner score >7 in both groups. CONCLUSION: At 5 years after ACL repair with DIS, instrumented knee joint laxity and PROs were comparable with those after ACL reconstruction. Although no significant difference was found between repair and reconstruction, a critical appraisal of the rates of recurrent instability (35% vs 20%, respectively) and revision surgery (38% vs 27%, respectively) is needed. Young age and a high preinjury activity level were the main risk factors for recurrent instability in both groups. However, single-stage revision ACL reconstruction was possible in each case in the ACL repair group. Although ACL reconstruction remains the gold standard in the treatment of ACL tears, the present study supports the use of ACL repair with DIS as a feasible option to treat acute ACL tears in patients aged ≥25 years with low to moderate activity levels (Tegner score <7). REGISTRATION: DRKS00015466 (German Clinical Trials Register).