Synergistic effect of diamond-like carbon coating and micro-texturing on reducing mechanical and thermal damage during bone drilling

Cortical bone, as an anisotropic and heterogeneous material, is susceptible to mechanical and thermal damage during surgical drilling. Therefore, this paper investigates the application of diamond-like carbon (DLC) coatings and micro-texturing in bone drills and analyzes their synergistic effects in reducing mechanical and thermal damage. First, micro-textures are prepared on stainless steel rods and bone drills using laser subtractive processing technology. Then, DLC coatings are deposited on the surface of the textured round rod and the drill bit using plasma-enhanced chemical vapor deposition (PECVD). Tribological and bone drilling experiments are conducted according to the experimental protocol to evaluate the tribological properties of DLC-coated microtextured rods and to reveal the synergistic effect of DLC coating and micro-texturing in reducing mechanical and thermal damage during bone drilling. Tribological tests show that the DLC coating can reduce bone fragment adhesion and improve the lubrication properties of the microtextured surface. Compared with uncoated round rods, the average coefficient of friction of DLC-coated round rods is reduced by 3.6%-9.4%. Cortical bone drilling experiments show that compared with uncoated microtextured drill bits, DLC-coated microtextured drill bits reduce drilling force by 4.9%-19.1%, maximum drilling temperature by 2.5%-4.9%, maximum thermal damage by 3.3%-6.5%, and surface roughness by 6.8%-14.6%. Furthermore, DLC-coated microtextured drill bits exhibit higher drilling stability and lower bone damage. These findings demonstrate that DLC coating and micro-texturing have a synergistic effect in improving drilling performance and reducing drilling damage, providing guidance for the development of high-performance surgical drills.