Thermometry during coblation and radiofrequency ablation of vertebral metastases: a cadaver study

To evaluate safety of coblation of simulated lytic metastases in human cadaveric vertebral bodies by measuring heat distribution during thermal tissue ablation and comparing it to radiofrequency ablation (RFA). Three devices were compared: a 10 mm single-needle RFA electrode, a 20 mm array RFA electrode and the coblation device. To simulate bone metastases, a spinal tumor model was used stuffing a created lytic cavity with muscle tissue. Measuring of heat distribution was performed during thermal therapy within the vertebral body, in the epidural space and at the ipsilateral neural foramen. Eight vertebral bodies were used for each device. Temperatures at heat-sensitive neural structures during coblation were significantly lower than using RFA. Maximum temperatures measured at the end of the procedure at the neural foramen: 46.4 A degrees C (+/- 2.51; RFA 10 mm), 52.2 A degrees C (+/- 5.62; RFA 20 mm) and 42.5 A degrees C (+/- 2.88; coblation). Maximum temperatures in the epidural space: 46.8 A degrees C (+/- 4.7; RFA 10 mm), 49.5 A degrees C (+/- 6.48; RFA 20 mm) and 42.1 A degrees C (+/- 2.5; coblation). Maximum temperatures measured within the vertebral body: 50.6 A degrees C (+/- 10.48; RFA 10 mm), 61.9 A degrees C (+/- 15.39; RFA 20 mm) and 54.4 A degrees C (+/- 15.77; coblation). In addition to RFA, the application of coblation is a safe method to ablate vertebral lesions with regards to heat distribution at heat-sensitive neural spots. The measured temperatures did not harbor danger of thermal damage to the spinal cord or the spinal nerves.