Comparison of the Effect of Oral Mucosa Stem Cell Therapy and Standard Surgical Repair on Pain Relief, Healing, and Shoulder Function in Patients with Rotator Cuff Muscle Tear: A Randomized Clinical Trial

The aim of this study is to evaluate the effect of oral mucosa stem cells compared with standard surgical repair on pain relief, tissue healing, and shoulder function in patients with rotator cuff muscle tear.

Randomized, double-blind, parallel-group, phase 2 clinical trial on 20 patients; randomization was performed using a random number table generated in SPSS, with allocation concealed in sealed opaque envelopes.

The study is conducted in the orthopedic department and operating room of Shahid Bahonar Hospital, Kerman. Stem cell sampling is performed by an independent team, and injections are carried out by the same surgeon. Patients and outcome assessors are blinded to the type of treatment. Follow-up continues for three months after surgery.

Participants include patients over 18 years of age with full-thickness supraspinatus tendon tear and shoulder pain or weakness lasting more than three months; exclusion criteria include pregnancy, shoulder osteoarthritis, previous shoulder surgery or fracture, rheumatic diseases, chronic corticosteroid use, coagulation disorders, and severe uncontrolled comorbid diseases.

The intervention group receives oral mucosa stem cell therapy combined with standard surgical repair; the control group receives standard surgical repair without stem cell injection.

Shoulder pain intensity based on Visual Analogue Scale (VAS); shoulder range of motion; shoulder function using Constant score; tendon healing on follow-up MRI.

In this study, eligible patients were randomly assigned to either the intervention group (oral mucosa stem cell therapy combined with standard surgical repair) or the control group (standard surgical repair only) after initial assessment and obtaining written informed consent. Randomization was simple randomization, and the unit of randomization was individual. The random sequence was generated using a random number table in SPSS version 26 by an independent researcher who was not involved in the intervention or outcome assessment. To ensure allocation concealment, the randomization codes were sealed in opaque, sequentially numbered envelopes. Each envelope was opened only at the time of participant enrollment, ensuring that neither the surgeon nor the outcome assessor was aware of the allocation beforehand.

A double-blind design was applied in this trial. Participants were unaware of their group assignment (whether they received stem cell injection or not). All patients underwent the same surgical procedure with identical incisions to prevent awareness of treatment differences. Stem cell sampling and preparation of the suspension were performed by an independent laboratory team, separate from the surgical staff. The injection (stem cell suspension or normal saline) was administered by the same surgeon, who was blinded to the content of each coded syringe prepared by the independent team. Nurses and physiotherapists responsible for postoperative care were not informed about group allocation. The evaluator of shoulder function and the data analyst were also blinded to the intervention type to minimize measurement and interpretation bias. Randomization codes were opened only after completion of data collection by the principal investigator.