Thermal capsular shrinkage: Basic science and clinical applications

Recently, the use of thermal energy to shrink the redundant glenohumeral jo int capsule in patients with instability has generated a great deal of inte rest. Proponents assert that the procedure avoids the need for an open stab ilization and it may be used as an adjunct to an open or arthroscopic capsu lolabral repair. The use of nonablative thermal energy to shrink soft-tissu e collagen appears to induce ultra-structural and mechanical changes at or above 60 degreesC. The microscopic changes reflect the unwinding of the col lagen triple helix and loss of the fiber orientation. The fibrils contract into a shortened state and reactive fibroblasts have been shown to grow int o this treated area and synthesize the collagen matrix. The biomechanical p roperties of the tissue do not appear to be detrimentally altered if shrink age is limited to less than 15% and if ablation or excess focal treatment i s avoided. The endpoint of optimal shrinkage is not known and clinical esti mations of tissue changes and volumetric reduction are used as guides to tr eatment. The first clinical follow-up study was only recently published in the peer-reviewed literature and prior preliminary reports were optimistic regarding the use of thermal energy for the treatment of glenohumeral insta bility. Thermal capsular shrinkage has been used as an adjunct to a capsulo labral repair, as well as an isolated treatment for the disorders of intern al impingement and multidirectional instability. Additional evaluation is n ecessary to determine the optimal quantity of energy needed for tissue shri nkage without inadvertent tissue destruction. The long-term clinical effect , mechanical propel-ties, and durability of the newly produced collagen nee d to be analyzed further. The basic science and clinical applications of th is newly applied technology are reviewed in this article.