Histologic evaluation of the glenohumeral joint capsule after the laser-assisted capsular shift procedure for glenohumeral instability

Glenohumeral joint capsule obtained from 42 patients who had undergone an a rthroscopic laser-assisted capsular shift procedure was evaluated histologi cally. A total of 53 samples from the anterior inferior glenohumeral ligame nt of the joint capsule were collected before and at various times after th e procedure (range, 0 to 38 months). Despite glenohumeral instability, join t capsule of the patients before the procedure showed no significant histol ogic lesions. Laser treatment significantly altered the histologic properti es of the tissue as evidenced by hyalinization of collagen and necrotic cel ls (time 0). Tissues sampled during the short-term period (3 to 6 months) a fter the procedure demonstrated fibrous connective tissue with reactive cel ls 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 sho wed persistent synovial, cellular, and vascular reaction even after 1 year postoperatively, the cause of which is unclear. This study revealed histolo gic evidence of robust tissue healing and maturation after thermal treatmen t by the laser-assisted capsular shift procedure, although mechanical and b iochemical characterization of the tissue was not evaluated. Correlation wi th clinical follow-up must be performed to further clarify the advantages a nd disadvantages of this procedure.