Currently, two different methods of applying radiofrequency (RF) energy (monopolar
and bipolar) are available to the surgeon for thermal shortening of the shoulder capsule.
The objective of this study was to investigate the temperature changes and the thermal
conduction across the human inferior glenohumeral ligament (IGHL) during radiofrequency
Thermistors were secured onto both the intra-articular and extra-articular surfaces
of human IGHL. Monopolar RF energy and bipolar RF energy were delivered to the intra-articular
surface at the manufacturer’s recommended settings. Pre-treatment and post-treatment
ligament lengths, widths, heating times, and temperatures were measured and compared.
For the monopolar devices, temperature spikes to 89°C were recorded for the set temperature
of 67°C, averaging 77°C ± 10°C. Temperatures across the ligament averaged 48°C ± 3°C.
For both devices, the IGHL became thicker with higher RF settings. Recorded temperatures
decreased as distance increased from the point of application. Maximum temperatures
occurred at least 6 to 7 seconds after cessation of energy application.
The bipolar and monopolar devices had similar conduction times across the ligament,
suggesting that this occurs by simple diffusion of heat. Bipolar and monopolar devices
were equally efficacious for capsular shrinkage if the extent of the shortening is
The thermal probe should not rest in one position for an extended period of time during
RF energy application because, as our study showed, the monitoring of temperature
or the visualization of tissue change is not efficacious for determining the end point
of thermal shrinkage of the shoulder capsule.