The effect of thermal heating on the length and histologic properties of the glenohumeral joint capsule.

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.