Does an Injection of Adipose-Derived Mesenchymal Stem Cells Loaded in Fibrin Glue Influence Rotator Cuff Repair Outcomes? A Clinical and Magnetic Resonance Imaging Study

Background: The mesenchymal stem cell (MSC)–based tissue engineering approach has been developed to improve the treatment of rotator cuff tears. Hypothesis/Purpose: The purpose was to determine the effect of an injection of adipose-derived MSCs loaded in fibrin glue during arthroscopic rotator cuff repair on clinical outcomes and to evaluate its effect on structural integrity using magnetic resonance imaging (MRI). The hypothesis was that the application of adipose-derived MSCs would improve outcomes after the surgical repair of a rotator cuff tear. Study Design: Cohort study; Level of evidence, 3. Methods: Among 182 patients treated with arthroscopic surgery for a rotator cuff tear, 35 patients treated with arthroscopic rotator cuff repair alone (conventional group) were matched with 35 patients who underwent arthroscopic rotator cuff repair with an injection of adipose-derived MSCs loaded in fibrin glue (injection group) based on sex, age, and lesion size. Outcomes were assessed with respect to the visual analog scale (VAS) for pain, range of motion (ROM) (including forward flexion, external rotation at the side, and internal rotation at the back), and functional measures of the Constant score and University of California, Los Angeles (UCLA) shoulder rating scale. Repaired tendon structural integrity was assessed by using MRI at a minimum of 12 months after surgery, and the mean clinical follow-up was 28.8 ± 4.2 months in the conventional group and 28.3 ± 3.8 months in the injection group. Results: The mean VAS score at rest and during motion improved significantly in both groups after surgery. However, there were no significant differences between the groups at the final follow-up ( P = .256 and .776, respectively). Compared with preoperative measurements, forward flexion and external rotation at the side significantly improved at the final follow-up in both groups (all P < .05). However, no significant improvements in internal rotation at the back were observed in either group ( P = .625 and .834 for the conventional and injection groups, respectively). There were also no significant differences between the groups at the final follow-up for any of the 3 ROM positions (all P > .05). The mean Constant score and UCLA score improved significantly in both groups after surgery, but there were no significant differences between the groups at the final follow-up ( P = .634 and .302, respectively). MRI indicated a retear rate of 28.5% in the conventional group and 14.3% in the injection group ( P < .001). Conclusion: This study revealed that an injection of adipose-derived MSCs loaded in fibrin glue during rotator cuff repair could significantly improve structural outcomes in terms of the retear rate. There were, however, no clinical differences in the 28-month period of follow-up. Although still in the early stages of application, MSC augmentation of surgical rotator cuff repair appears useful for providing an adequate biological environment around the repair site.