Mechanical changes induced by thermal stimulation in collagenous tissue.

Radiofrequency thermal stimulation is used as a therapeutic procedure for joint laxity, but its thermal effects are still controversial. Although collagen shrinkage may be expected, this conclusion is empirical and not universally accepted. The purpose of this study was to investigate the mechanical response of collagen to thermal stimulation. A longitudinal cut was made in rabbit Achilles tendons previously marked with monofilament sutures. The distance between the sutures was measured before the cut, just after it was made, and after 8 weeks. The results did not show any shrinkage or significant change in tendon resistance to traction 8 weeks after thermal stimulation; however, comparison with the opposite, normal tendon revealed a statistically significant increase in tendon stiffness.