Primary single suture anchor re-fixation of anterior cruciate ligament proximal avulsion tears leads to good functional mid-term results: a preliminary study in 12 patients

BACKGROUND Current studies demonstrate encouraging short-term results after primary anterior cruciate ligament (ACL) suture anchor repair. However, earlier studies reported deterioration of knee function at 5-year follow-up following good clinical short-term recovery. Therefore, the aim of this study was to evaluate clinical long-term results after primary ACL repair at a minimum 5-year follow-up. METHODS In a retrospective study, 13 patients were included between 2009 and 2012. Inclusion criteria were an acute proximal, femoral avulsion tear of the ACL with good tissue quality and sagittal instability in a healthy, demanding patient. Patients suffering proximal tibial fractures, arthrosis, or multiligamentous injuries of the knee were excluded. The ACL was anchored to the footprint by a single 2.9-mm push lock anchor, followed by additional microfracturing. For follow-up, patients were evaluated according to Lysholm score, modified Cincinnati score, and Tegner activity score. Clinical examination was performed using Lachman and pivot-shift testing and range of motion and sagittal stability measurement, using a Rolimeter. RESULTS Mean follow-up was 79 (range 60 to 98) months. One patient was lost to follow-up, and 11 out of 12 patients were examined clinically. Eight patients achieved good subjective and clinical outcome. One patient suffered an early re-tear, and one patient with additional patellar tendon tear and one patient with polyarthritis demonstrated poor subjective and clinical results due to lasting instability. Seven out of 12 patients reached preoperative Tegner activity score postoperatively again. The mean Lysholm score was 85.3 points, mean subjective IKDC score was 87.3 points, and mean modified Cincinnati score was 83.8 points. Rolimeter measurements demonstrated a mean side-to-side difference of 2 (range 1-5) mm. CONCLUSION In the current study, primary surgical re-fixation of proximal, femoral ACL avulsion tears using single suture anchor repair resulted in good to excellent clinical mid-term outcomes. However, in cases of additional serious damage to extensor structures or systemic rheumatic disease, loss of function and unsatisfying clinical results occurred. Further prospective randomized controlled trials are necessary to confirm the encouraging long-term results of this study. TRIAL REGISTRATION Bavarian National Medical Chamber of Physicians, file number 2016-095. German Clinical Trials ( DRKS00013059 ).