Sufficient MRI graft structural integrity at 9months after anterior cruciate ligament reconstruction with hamstring tendon autograft.

Abstract

To assess the MRI-measured structural integrity of hamstring autograft at 9months after anterior cruciate ligament reconstruction (ACLR) surgery. A prospective cohort study was conducted including 34 patients (mean age 36.8 ± 11.8years; 73.5% males) who underwent ACLR with hamstring autograft. In addition, 36 patients (mean age 39.2 ± 10.5years; 69.4% males) without any ACL injury were also reviewed and served as control group. The primary outcome used for examining graft maturity at 9months after ACLR was the MRI-based signal-to-noise quotient (SNQ) of reconstructed ACL. SNQ values were stratified into 3 different categories: excellent: < 0.1; good: ≥ 0.1 and ≤ 0.19; fair: ≥ 0.2. The KT-1000 knee arthrometer was used to measure the side-to-side difference in the anterior tibial translation between the ACLR knee and the contralateral healthy knee in the ACLR group. Reconstructed ACLs were found with a mean SNQ of 0.078 ± 0.061, while almost all ACL-reconstructed patients (97%; 33 out of 34) were found with excellent or good SNQ values (< 0.019). The mean KT-1000 in the ACLR group was 0.071mm ± 0.926mm, while there were no patients in the ACLR cohort with a KT-1000 value > 3mm. The mean 9-months MRI-based SNQ of ACLR group was significantly higher compared to the mean MRI-based SNQ of the control group (p < 0.001). Multiple regression analysis showed no correlation between SNQ and age, gender, time from injury to ACLR, graft size, or simultaneous treatment of additional intra-articular knee lesions. In this cohort of 34 ACL-reconstructed patients, 97% of hamstring tendon autografts demonstrated excellent/good MRI signal intensity and excellent functional results (KT-1000 < 3mm) at 9months after surgery. Based on this finding, it is suggested that return to sports after ACLR with hamstring autograft can be considered safe at 9months post surgery. Furthermore, while structural integrity of the graft has been achieved at this time point, statistical differences found in SNQ values of ACL-reconstructed patients compared to ACLs of healthy individuals highlight the continuing process of graft maturation and remodelling. Level III.