Twelve-Month Maturation Timeline of Quadriceps Tendon Autograft Signal Intensity Ratio After ACL Reconstruction...

Anterior cruciate ligament (ACL) injuries are among the most common sports-related injuries, accounting for about half of all knee injuries, and most athletes opt to undergo ACL reconstruction (ACLR). The quadriceps tendon (QT) ACLR has only recently been gaining popularity, and therefore few studies exist for evaluating the healing, or ligamentization, timeline of the QT autograft.

To evaluate the signal intensity (SI) ratio of the tendon QT autograft after ACLR during the first postoperative year.

Case series; Level of evidence, 4.

A prospective case series of 19 athletes (mean age = 15.63 years) with ACL rupture who underwent ACLR with a QT autograft underwent knee magnetic resonance imaging (MRI) at 4 time points: presurgery (PRE), 3 months postoperative (3M), 6 months postoperative (6M), and 12 months postoperative (12M). SI ratio was calculated across different anatomic landmarks, specifically the intra-articular tissue of the native ACL of the contralateral knee from the PRE time point; the QT graft in the intra-articular space at 3M, 6M, and 12M time points; and the posterior cruciate ligament at each visit, to be used as a reference value and account for visit-to-visit variations in the MRI signal. Means of the SI ratio were calculated at the full graft level, as well as segmented into either 4 or 24 segments for analysis.

At the full-graft level, there was a significantly higher SI ratio in the QT graft at 3M and 6M compared with the native contralateral ACL. By 12M, the full graft was most like the native contralateral ACL. Similarly at the 4 subsegment level, all regions except the distal segment had significantly higher SI ratios at 3M and 6M as compared with the native contralateral ACL. By 12M, all subsections of the graft were not significantly different from the native contralateral ACL.

The SI ratio of QT graft was increased at 3M and 6M after surgery and then returned close to that of the native ACL by 12M after surgery, which is largely consistent with the published maturational timeline of patellar tendon and hamstring tendon autografts.