Orbital drilling in orthopedics: A novel technique to mitigate drilling-induced mechanical damage

Bone drilling is a critical procedure in orthopedic surgery, essential for bone fixation. However, achieving consistently high-quality, damage-free holes remains a challenge, even with advanced drilling tools and techniques, as the process is conventionally performed manually using axial drilling units. This study introduces orbital drilling, a robot-assisted technique, as a novel approach in orthopedic applications to enhance the quality of drilled holes by addressing and mitigating drilling-induced mechanical damage. A comparative analysis of orbital and axial drilling techniques is conducted to elucidate the kinematics of both methods and assess the improvements in hole quality parameters achieved through orbital drilling. For the first time, forces generated during orbital drilling in bones are systematically monitored, and delamination damage at both the entry and exit points of the drilled bone tissue is comprehensively analyzed using advanced digital image processing techniques. Additionally, hole geometry is characterized using Coordinate Measuring Machines (CMM). Results demonstrate that orbital drilling reduces average forces by approximately 85% compared to axial drilling, due to improved load distribution and a reduced contact area. Using a multi- criteria decision-making approach (AHP-TOPSIS), the study reveals that orbital drilling significantly improves machining accuracy, including circularity, cylindricity, and aperture, while minimizing delamination damage, enhancing surface quality, and mitigating microcracks. Analysis of variance (ANOVA) further indicates that, in orbital drilling, cutting speed has a lower impact, whereas feed rate-related parameters play a more significant role compared to axial drilling. These findings represent a substantial advancement in addressing the current challenges associated with bone drilling and provide key insights into the mechanical failure mechanisms involved.