Histologic Evaluation of Thermal Capsulorrhaphy of Human Shoulder Joint Capsule With Monopolar Radiofrequency Energy During Short‐ to Long‐term Follow‐up

PURPOSE: The purpose of this study was to evaluate the histologic morphology of human shoulder joint capsule after thermal capsulorrhaphy with monopolar radiofrequency energy (mRFE) during short- to long-term follow-up. METHODS: This study comprised 27 patients who received an arthroscopic mRFE thermal capsulorrhaphy and 10 patients without mRFE treatment serving as the control group. Biopsy samples from 3 locations (anterior-superior, anterior-inferior, and posterior-medial) of the shoulder joint capsule were harvested from both the mRFE-treated patients and the control patients. The follow-up time for the mRFE treatment ranged from 3.5 to 62 months, which was divided into 3 groups: short, 3.5 to 12 months; medium, 14 to 25 months; and long, 31 to 62 months. The biopsy samples were analyzed via a histologic scoring system, evaluating an intact synovial layer, subsynovial edema, collagen morphology, cellularity, vascularity, and inflammatory cells. Histologic scores among each follow-up group were compared with each other and with those in the control group. RESULTS: There were no significant differences in the histologic categories of intact synovial layer, subsynovial edema, collagen morphology, and inflammatory cells among the control and mid- and long-term mRFE groups. The short-term mRFE group had greater increased cellularity and vascularity compared with the mid- and long-term groups, which progressively improved toward the appearance in the normal control group with time. CONCLUSIONS: After mRFE capsulorrhaphy, histologic analysis revealed that the mRFE-treated shoulder joint capsule had almost returned to normal, except for persistent cellularity and increased vascularity, which were present at up to 5 years after this procedure. LEVEL OF EVIDENCE: Level III, therapeutic case-control study.