Which Injection Is More Effective for Partial-Thickness Rotator Cuff Tear? Atelocollagen Versus Acellular Dermal Matrix.

Abstract

Backgroud: Collagen-inducing injections are emerging as new treatments for partial-thickness rotator cuff tears (PTRCTs). This study aimed to directly compare the effects of atelocollagen and acellular dermal matrix (ADM) injections on PTRCTs.

Methods: Between July 2019 and December 2021, 183 patients with PTRCTs who were treated with ultrasound-guided collagen injections were retrospectively enrolled. Two injections were administered at 3-month intervals at the supraspinatus tear site, and tendon integrity was evaluated 6 months after the first injection using magnetic resonance imaging (MRI). The patients were divided into 2 groups: atelocollagen injection (group 1, n = 49) and ADM injection (group 2, n = 41). Supraspinatus tear size was measured in T2 coronal and sagittal views. Outcomes were categorized into 3 groups by tear size change from initial to final follow-up: improved (< 0-2 mm), no interval change (-2 to 2 mm), and worsened (> 2 mm). Clinical scores and range of motion (ROM) were measured in both groups.

Results: The atelocollagen group showed improved outcomes in 34.7% of the patients, whereas 55.1% and 10.2% showed no interval change and worsening in the coronal plane, respectively. The ADM group showed improved outcomes in 48.8% of the patients, whereas 48.8% and 2.4% showed no interval change and worsened results in the coronal plane, respectively. The mean change in tear size was -1.02 ± 2.87 mm for group 1 and -2.31 ± 3.62 mm for group 2 (p < 0.05). In the sagittal plane, 20.4% of the patients in group 1 showed improvement, 77.6% showed no interval change, and 2% showed worsened outcomes. Group 2 showed improvement in 31.7% of patients, 58.5% showed no interval change, and 9.8% showed worsened outcomes. Tear size changed by -0.56 ± 1.90 mm for group 1 and -0.8 ± 2.37 mm for group 2 (p > 0.05). No significant differences were noted in the ROM between the 2 groups at any time. Clinical scores also showed no significant differences between the 2 groups, except for the Constant Shoulder Score at the 3-month follow-up.

Conclusions: Compared with atelocollagen injection, ADM injection resulted in a superior improvement in rotator cuff tendon integrity. However, clinical outcomes were comparable between the groups.