Diameter of Quadrupled Semitendinosus Autograft in Primary Anterior Cruciate Ligament Reconstruction Did Not Impact Early Revision Rate or Functional Outcome in a Large Cohort of Patients

Abstract

To determine whether the diameter of the quadrupled semitendinosus tendon (ST) graft in primary anterior cruciate ligament reconstruction (ACLR) is related to the risk of revision ACLR within 2 years of primary ACLR, postoperative knee laxity and patient reported knee outcome. Furthermore, to investigate whether smaller graft than estimated is related to revision ACLR. Patients who underwent primary ACLR with a quadrupled ST autograft at our institution, from January 2005 to December 2017 were identified. Data from the Swedish National Knee Ligament Registry (SNKLR) were collected up to two years or until revision surgery was registered within two years after primary ACLR. Knee laxity was assessed, pre-operatively and at 6-months follow up using the KT-1000 arthrometer (134 N anterior tibial load). The Knee injury and Osteoarthritis Outcome Score (KOOS) were collected preoperatively and at two years postoperatively from SNKLR. Based on anthropometric measurements (body height and weight) and sex the estimated quadrupled ST graft diameter was calculated. A total of 4,519 patients who underwent ACLR with a quadrupled ST autograft were included. The mean graft diameter was 8.3 mm± 0.7 mm; 8.0 mm± 0.6 mm for women and 8.6 mm ± 0.7 mm for men. The quadrupled ST graft diameter was not significantly correlated to revision ACLR. There was no significant difference in the ST graft diameter regarding post-operative knee laxity. The correlations between ST graft diameter and KOOS were weak, except for the "Sport and Recreation" subscale (P=.012). The quadrupled ST graft diameter was not significantly related to the need for early revision ACLR nor was related to postoperative knee laxity or patient reported outcome except for the KOOS "Sport and Recreation" subscale. Smaller ST graft than estimated was not a risk factor for revision ACLR. The outcome after ACLR is multifactorial and ST graft diameter is of no significant importance.