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

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.