Prospective Randomized Trial Of Biologic Augmentation With Mesenchymal Stem Cells In Patientsundergoing Arthroscopic Rotator Cuff Repair

Abstract

Objectives: To compare the clinical outcome of arthroscopic rotator cuff repair with and without augmentation with MSCs and to identify the incidence of persistent structural defects in the tendon following surgery Methods: Patients aged 18-70 undergoing repair of a full-thickness supraspinatus tear or partial thickness converted to full thickness tear determined by MRI were identified and prospectively enrolled. Exclusion criteria included involvement of the subscapularis tendon, revision surgery or irreparable tear. In the injection group, 60 cc of bone marrow aspirate was drawn from the iliac crest and processed to bone marrow aspirate concentrate (BMAC) using the Arthrex Angel System (Arthrex, Naples, FL). After completion of the rotator cuff repair, half of the BMAC was injected into the tendon at the junction of the bone and tendon while the other half was injected at the site of the footprint. The control group received a small 0.5 cm incision on the hip to maintain blinding. All patients underwent a shoulder exam pre-operatively as well as at 3 months, 6 months, 1 year and 2 years post-operatively. All patients completed the Standardized Shoulder Test (SST), ASES, Constant, SANE, and VR/SF-12 questionnaires preoperatively as well as 3 months, 6 months, 12 months, 18 months and 24 months postoperatively. Baseline questionnaire scores were subtracted from scores at each timepoint to find the improvement and unpaired T-tests were performed between the two groups. Additionally, all patients underwent an MRI at 12 months postoperatively to evaluate the rotator cuff. MRIs were read by a board-certified orthopaedic surgeon and graded using the Sugaya classification system. Results: 34 patients were randomized to the control group and 28 were randomized to the receive the injection. Average BMA MSC concentration (#/uL) was 2.63 compared to 14.95 for the BMAC MSC concentration. As a result, the BMAC was on average 5.68 times as concentrated with respect to MSC per ul when compared to the BMA. Patients received an average BMAC volume of 2.7 mL, equating to 50410.79 +/- 25375.45 mesenchymal stem cells. There were no differences across improvement in patient reported outcomes from baseline between the control group and the group randomized to receive the injection, except for the Standardized Shoulder Test at 6 months. The mean SST score at 12 months was 87.50 in the BMAC group compared with 85.32 in the control (p=0.18). The mean ASES score at 12 months was 87.38 in the BMAC group and 89.96 in the control group (0.67). Mean Sugaya score for the control group was 3.25±1.12 (range 2-5). Mean Sugaya score for the injection group was 2.60±0.91 (range 2-5). Sugaya scores showed statistical significance with Chi-squared test at 1 year postoperative MRI (p=0.0012), and approached statistical significance with independent t test (p=0.067). Conclusion: MSCs injected into the shoulder at the time of rotator cuff repair show improved tendon quality on post-operative MRI at 1-year post-op, based on the Sugaya scoring system, with the difference in mean Sugaya score approaching significance. Further investigation is needed into this new and evolving treatment; however, it shows promise for improving the rate of rotator cuff repair healing and overall functional outcome.