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Glenohumeral joint capsule obtained from 42 patients who had undergone an arthroscopic laser-assisted capsular shift procedure was evaluated histologically. A total of 53 samples from the anterior inferior glenohumeral ligament of the joint capsule were collected before and at various times after the procedure (range, 0 to 38 months). Despite glenohumeral instability, joint capsule of the patients before the procedure showed no significant histologic lesions. Laser treatment significantly altered the histologic properties of the tissue as evidenced by hyalinization of collagen and necrotic cells (time 0). Tissues sampled during the short-term period (3 to 6 months) after the procedure demonstrated fibrous connective tissue with reactive cells and vasculature. Collagen and cell morphology returned to normal in the middle- to long-term period (7 to 38 months) after the procedure, while the number of fibroblasts remained elevated. Joint capsule collected from the shoulders of six patients who experienced stiffness after the procedure showed persistent synovial, cellular, and vascular reaction even after 1 year postoperatively, the cause of which is unclear. This study revealed histologic evidence of robust tissue healing and maturation after thermal treatment by the laser-assisted capsular shift procedure, although mechanical and biochemical characterization of the tissue was not evaluated. Correlation with clinical follow-up must be performed to further clarify the advantages and disadvantages of this procedure.

The purpose of this study was to evaluate the effect of temperature on shrinkage and the histologic properties of glenohumeral joint capsular tissue. Six fresh-frozen cadaveric shoulders were used for this study. Seven joint capsule specimens were taken from different regions from each glenohumeral joint and assigned to one of seven treatment groups (37 degrees, 55 degrees, 60 degrees, 65 degrees, 70 degrees, 75 degrees, 80 degrees C) using a randomized block design. Specimens were placed in a tissue bath heated to one of the designated temperatures for 10 minutes. Specimens treated with temperatures at or above 65 degrees C experienced significant shrinkage compared with those treated with a 37 degrees C bath. The posttreatment lengths in the 70 degrees, 75 degrees, and 80 degrees C groups were significantly less than the pretreatment lengths. Histologic analysis revealed significant thermal alteration characterized by hyalinization of collagen in the 65 degrees, 70 degrees, 75 degrees, and 80 degrees C groups. This study demonstrated that temperatures at or above 65 degrees C caused significant shrinkage of glenohumeral joint capsular tissue. These results are consistent with histologic findings, which revealed significant thermal changes of collagen in the 65 degrees, 70 degrees, 75 degrees, and 80 degrees C groups. To verify the validity of laser application for shrinkage of joint capsule, studies designed to compare these findings with the effects of laser energy must be performed.