Thermal capsulorrhaphy treatment of shoulder instability: basic science.

Thermal capsulorrhaphy is a new treatment modality for shoulder instability, where the joint capsular tissue is heated and reduced in length by laser or radiofrequency energy to regain joint stability. Experimental studies have shown that (1) joint capsular tissue can be modified significantly (shortened) by thermal energy at the temperature range of 70 degrees to 80 degrees C; (2) thermal energy causes immediate deleterious effects such as loss of the mechanical properties, collagen denaturation, and cell necrosis; (3) thermally treated tissue is repaired actively by a residual population of fibroblasts and vascular cells, with concomitant improvement of mechanical properties; (4) the shrunken tissue stretches with time if the tissue is subjected to physiologic loading immediately after surgery; and (5) leaving viable tissue between treated regions significantly improves the healing process. Therefore, the application of thermal energy to achieve joint stability relies on an initial effect (shrinkage), and to a great extent the tissue's healing response to regain the tissue's mechanical properties. Particularly, induction of active repair and joint capsular thickening with tissue remodeling regulated by functional demand seem to be essential factors for a successful outcome. Thermal treatment causes an initial deleterious effect on the tissue's properties, and overtreatment can lead to severe immediate and permanent tissue damage. In addition, scientific data of newly developed devices are limited, and the information from manufacturers often is unreliable and misleading. Carefully controlled long-term clinical and scientific studies should be done to additionally clarify the advantages and disadvantages of this technique.