Seventy percent long-term survival of the repaired ACL after dynamic intraligamentary stabilization

PURPOSE Primary repair of the anterior cruciate ligament (ACL) is regaining popularity. Long-term results are lacking. The purpose of the current study was to determine the survival of the primarily repaired ACL after dynamic intraligamentary stabilization. METHODS Between 2011 and 2013, 57 patients with acute proximal ACL ruptures underwent DIS repair within 3 weeks from injury and were available for final follow-up at least 5 years postoperatively. Failure as an end point was defined as conversion to ACL reconstruction, failure to restore stability with persisting laxity side-to-side laxity of > 5 mm or a late-traumatic re-rupture or loss of stability. Kaplan-Meier survival analysis was performed. RESULTS Kaplan-Meier survival analysis demonstrated an overall survival of 70.0% (standard error SE 6.6%) at 74 months follow-up. Patients performing competitive sports prior to injury demonstrated an inferior long-term ACL survival of 56.4% (SE 11.6%). Patients performing recreational sport activities demonstrated a survival rate of 79.2% (SE 7.7%). The one factor demonstrating a direct influence on failure after adjustment was a high-pre-injury level of physical (odds ratio 4.0 confidence interval 1.0-15.8, p = 0.04). CONCLUSION The minimum 5 years survival rate after primary ACL repair using this technique was 70%. This value dropped to 56% in highly active patients performing competitive sports. Patients not suffering failure of repair demonstrated adequate restoration of knee laxity and high satisfaction. This study not only underlines the potential of ACL repair, but also highlights the danger of the procedure if strict patient selection is not appreciated. LEVEL OF EVIDENCE Level IV.