Thermal and Electric Energy Fields by Noninvasive Monopolar Capacitive-Coupled Radiofrequency: Temperatures Achieved and Histological Outcomes in Tendons and Ligaments

Objective

To determine whether noninvasive monopolar capacitive-coupled radiofrequency (mcRF) can produce energy and thermal fields capable of breaking-down collagen molecules in deep connective structures without damaging untargeted tissues as evidenced by temperatures achieved and histological outcomes.

Design

Basic science study on fresh untreated cadaveric specimens.

Setting

Orthopaedic Research of Virginia (Institutional).

Methods

Two upper and two lower extremities from cadaveric specimens were obtained for the study. Anatomical structures were surgically exposed. Fluoroptic thermometers were implanted into the mid-substance of the targeted structures as well as in the skin above the structures to be studied. mcRF pulses were delivered to the area of interest, and temperatures were recorded every second. Multiple samples of tissue from each treatment site and stage of treatment were harvested for analysis.

Outcome Measures

Outcomes were evaluated by temperature changes in response to energy fields, multiobserver histological analysis under regular and polarized light, and direct observation of the tissues in the areas exposed to RF energy.

Results

Temperatures recorded at the targeted structures reached above 50°C, as evidenced by the implanted thermometers. Histological analysis under regular and polarized light evidenced a progressive pattern of collagen denaturation that correlated well with temperatures recorded.

Conclusion

This study established a direct relationship between noninvasive mcRF energy and temperatures recorded in deep structures (P < .001). Histological examination under regular and polarized light suggested that collagen changes are dose related. No evidence of damage to the nontargeted structures or to the tissue superficial to targeted structures was observed. As it has been demonstrated in survival animal studies, it is anticipated that the outcome of the changes induced in collagen fibers would trigger a desirable wound healing response. These findings can provide a meaningful context to the ongoing clinical use of mcRF.

• ⁎ Disclosure: 1B, stock and stock options in the manufacturer of the device used in this study
• ⁎ Disclosure: 1B, stock and stock options in the manufacturer of the device used in this study