Type I Atelocollagen Interposition Within the ACL Graft During ACL Reconstruction: An Exploratory Clinical and MRI-Based Study

Background and Objectives: Atelocollagen, a purified collagen derivative, has demonstrated potential benefits in various orthopedic applications; however, its role in anterior cruciate ligament (ACL) reconstruction remains unclear. This study aimed to compare magnetic resonance imaging (MRI) graft signal following ACL reconstruction with and without atelocollagen interposition and to evaluate its effects on knee joint laxity and clinical outcomes. Materials and Methods: A retrospective review was conducted on patients who underwent primary ACL reconstruction using hamstring autografts between March 2015 and July 2023. Patients were divided into two groups: without atelocollagen (Group N) and with atelocollagen interposition (Group C). The primary outcome was ACL graft signal intensity (intra-articular and intra-tunnel) on 1-year postoperative MRI. Secondary outcomes included tunnel widening, knee joint laxity, and patient-reported outcome measures (PROMs). Results: A total of 57 patients (Group N: 34; Group C: 23) were analyzed. Baseline characteristics were comparable between groups. Group C had a higher proportion of thicker graft constructs (quintuple/sextuple: 73% vs. 17.6%, p < 0.001) and more frequent concomitant anterolateral ligament reconstruction (78.3% vs. 8.8%, p < 0.001). No significant difference in intra-articular graft signal was observed. However, femoral intra-tunnel graft signal was significantly lower in Group C (p = 0.018), accompanied by reduced femoral tunnel widening (p < 0.001). Tibial tunnel widening, knee joint laxity, and PROMs did not differ significantly at 1 and 2 years. In multivariable analysis, atelocollagen interposition was associated with reduced femoral tunnel widening (B = −1.1, p = 0.025). Conclusions: Atelocollagen interposition during ACL reconstruction was associated with more favorable intra-tunnel graft healing signals and reduced femoral tunnel widening, although it did not appear to influence short-term clinical outcomes.