Electrocautery Induced Damage of Total Knee Implants

Wear, Material Transfer, and Electrocautery Damage Are Ubiquitous on CoCrMo Femoral Knee Retrievals

Despite high total knee arthroplasty (TKA) survivorship after 10 years (92%-99%), a gap persists where patient satisfaction lags clinical success. Additionally, while cobalt chrome molybdenum (CoCrMo) use decreases in primary total hip arthroplasty, the alloy continues to be widely used in TKA femoral components. In vivo, CoCrMo degradation may be associated with adverse local tissue reactions (ALTR) and compared with the hip, the damage mechanisms that may release metal in the knee and the potential biological effects remain poorly understood. In this study, we characterized the damage on 50 retrieved CoCrMo femoral knee implants paired with 19 titanium alloy and 31 CoCrMo tibial baseplates. We asked (1) what damage modes can release CoCrMo debris in vivo from femoral components and (2) how frequently does the damage occur? First, we developed a semiquantitative scoring system for abrasive wear. Then, we characterized damage modes on CoCrMo femoral implants using digital optical microscopy (DOM), scanning electron microscopy (SEM), and energy dispersive X-ray spectroscopy (EDS). We found that wear, electrocautery damage, and Ti-6Al-4V material transfer were ubiquitous. Of the 50 CoCrMo femoral implants we investigated, we documented wear on 100% (n = 50/50), electrocautery damage on 98% (n = 49/50), and Ti-6Al-4V material transfer to the posterior condyles on 95% (n = 18/19). Our results suggest that these damage modes may be more prevalent than previously thought and may act as metal release mechanisms in vivo.

Electrocautery-induced molten metal particle generation from total joint replacements: Morphology and chemistry

Electrosurgical techniques are used during surgery to cauterize, and their damaging effects have primarily been documented in terms of tissue necrosis, charring, and localized heat accumulation. Metallic implants as well as the surgical blade can experience incidental electrosurgical current arcing that results in the generation and transfer of melted metallic particles. This work examines the composition, particle size distribution, and chemical state of the melted alloy surfaces and particles produced in vitro. Using scanning electron microscopy and energy dispersive spectroscopy, a flash-melting particle generation phenomenon between source 304 SSL blades and polished cobalt-chromium-molybdenum (CoCrMo) and titanium-6-aluminum-4-vandaium (Ti6Al4V) surfaces was documented where 304 SSL mixed heterogeneously with the CoCrMo and Ti6Al4V ejecting "splatter" particles from the cautery site. The spherical micron-sized particles were embedded with sub-micron-sized particles with 42% of the total sample population measuring between 0.25 and 0.35 μm in diameter. CoCrMo-304 SSL particles were principally made of high concentrations of iron, oxygen, and nickel with embedded sub-micron-sized particles containing oxygen, chromium, and cobalt with lower concentrations of iron and molybdenum. Ti6Al4V-304 SSL interactions resulted in similar micron-sized particles made up of high concentrations of iron, nickel, and chromium with embedded sub-micron-sized particles containing titanium, oxygen, and small amounts of aluminum. X-ray photoelectron spectroscopy of damaged CoCrMo surfaces confirmed the presence of chromium (VI) following dry electrocautery contact in coagulation mode. The structural effects of electrocautery-induced damage are becoming visible in retrieval analysis, but the long-term physiological implications during the lifetime of the implant from this damage mode have yet to be defined.