Abstract
Recently, our lab has made observations of metal damage patterns from retrieval studies that appeared to be cellular in nature [1]. This type of damage presented on about 74% of the retrieved implants and was attributed to inflammatory cells (termed ICI corrosion) [1]. An alternate hypothesis arose surrounding the use of electrosurgery in total joint arthroplasty (TJA). In TJA, where surgery occurs around metallic devices, the interactions of the high voltage, high frequency current created by an electrosurgical generator and the implant need to be better understood. In order to explore the effects electrosurgical currents have on metal implants, the interaction of a model system of highly polished metal disks and a standard electrosurgical generator (ConMed, Utica, NY) was evaluated in various modes and power settings. The disks were made of CoCrMo or Ti-6Al-4V alloys and were polished to a mirror finish for use and placed directly on the return electrode pad used in patients. Both coagulation and cut modes were evaluated, as well as both monopolar and bipolar configurations in wet and dry conditions using a blade-shaped tip. In wet cases, the disks were wet with phosphate buffered saline prior to the test to simulate body fluids in contact with the implant during current application. In all cases, surface damage was generated on both surfaces and was readily observed as a direct result of the current interacting with the metal (Fig. 1 and 2). Direct contact with the metal, regardless of a dry or wet surface, resulted in pitting and oxide buildup at the contact area. Non-contact activation in proximity to the surface or contact with fluid on the surface caused arcing and created damage that was more widespread over the area of fluid contact with the surface. The damage patterns created on the wetted surface by the electrosurgical unit looked very similar to the patterns we previously attributed to inflammatory cells. More specifically, it produced circular, ruffled areas with centralized pits and occasionally presented trail- and weld-like features (Fig. 2). While these results show that some of the damage previously reported to be from ICI corrosion is indeed the result of electrosurgery, there are still cases in retrievals that cannot be explained by this process and the corrosion reaction to alloys exposed to ROS-based molecules demonstrate significant acceleration of corrosion. Thus, ICI corrosion is still a viable hypothesis. Surgeons utilizing electrosurgical systems in proximity to metallic orthopedic implants need to exercise caution as the discharge of electrical energy through these implants can induce localized surface damage and may result in other adverse effects to the metal implants.
Ultimately, we would like to update the community on the nature of the damage we previously reported and more importantly bring to light the possibility of surgeon-induced damage to the implant as a result of electrosurgical methods.
