Aim: Radio-frequency treatment is used clinically in unstable joints to reduce the length of the supporting soft tissues to help provide stability. The mechanical properties after treatment have not been adequately studied. Since there is a change in the tissues’ ultra-structure with treatment we hypothesised that different collagenous tissues may have varying responses to radio-frequency treatment.

Methods: Ovine extensor tendons and cadaveric gleno-humeral capsules were tested on a MTS machine to investigate the dynamic and failure properties before and after radio-frequency treatment. Three radio- frequency treatments of different power (5, 10 and 20W) were used and two different treatment times (10s and 30s) to investigate the effects of treatment power and time on changes in the mechanical properties.

Results: The tissue shortening that was produced in the tendons and capsules was progressive with increases in treatment wattage and time. The tendon failure-force and stiffness were significantly reduced by the radio-frequency treatment but no significant changes were found in the capsules. Considering the dynamic properties only, the tendons showed significant changes with treatment. The mechanical properties were significantly different between control and treated groups but not between the treatment settings.

Conclusions: The tissue type altered the effect of radio-frequency treatment on the mechanical properties. Varying the treatment wattage and time did not significantly alter the changes observed with the largest difference being between control and treated tissue at any treatment setting. Therefore, radio frequency was proven to shorten collagenous tissues in a predictable manner but changes to the mechanical properties depend on the tissue type.