Thermal modification of collagen

Shoulder capsular shrinkage has recently been proposed as a therapeutic mod ality in a select group of patients with instability. Basic science researc h studying the mechanism of collagen shrinkage and the effect of shrinkage on the tissue's mechanical properties is essential to define the ideal proc ess by which to achieve optimal tissue shrinkage. Tissue shrinkage is a fun ction of both time and temperature. This relationship was studied and a mod el was derived to describe the relationship mathematically. Tissue shrinkag e rate was extremely sensitive to temperature changes. The purpose of this study was to shrink collagenous tissue thermally and then to measure the me chanical property changes as a function of tissue shrinkage. Uniaxial tensi le testing of normal and heat-shrunken bovine tendon was carried out, and a model was developed to express the relationship between shrinkage and mech anical properties. We found that the mechanical properties decreased with i ncreasing shrinkage, and that the maximal allowable shrinkage before signif icant material property changes occurred was between 15% to 20%. Ultrastruc tural analysis with transmission electron microscopy showed denaturation of the collagen fibrillar structure and provided direct support for the obser ved material changes.