Comparison of thermal spread with the use of an ultrasonic osteotomy device: Sonopet ultrasonic aspirator versus misonix bonescalpel in spinal surgery.

Background: The development of high speed rotating burrs has greatly advanced spinal surgery in recent years. However, they produce unwanted frictional heat and temperature elevation during the burring process. We compare the misonix bone scalpel (MBS) and the Sonopet ultrasonic aspirator to assess which would be the safer device in terms of the risk of thermal injury following laminectomy.

Methods: We describe an experimental nonrandomized study comparing two ultrasonic osteotomy devices. We use the device tip temperature and temperature of inner cortex of the lamina, following laminectomy, as the primary outcome. Our secondary outcome is to assess which device is associated with a lower risk of osteonecrosis and potential thermal injury to surrounding dura and nerves.

Results: The average device tip temperature for the Sonopet ultrasonic aspirator following the process of laminectomy was 36.8 with a maximum temperature of 41.8°C. The average device tip temperature for the MBS following laminectomy was 48.6 with a maximum temperature of 85.3°C.

Conclusion: Our results have demonstrated the safety of the Sonopet ultrasonic aspirator with the Nakagawa serrated knife with temperatures below the threshold for osteonecrosis and thermal neural injury. However, the MBS has shown to occasionally reach high temperatures above the threshold of potential thermal injury to surrounding nerves and dura for a very short period of time. We advise to withdraw and re-insert the ultrasonic tip repeatedly to re-establish adequate cooling and lubrication. Further studies should be carried out using cadaveric bone at body temperature to simulate more accurate results.