Experimental Study of Thrust Force and Torque for Drilling Cortical Bone.

Area of Science:

• Biomechanical Engineering
• Orthopedic Surgery
• Materials Science

Background:

• Drilling forces during bone procedures can lead to adverse outcomes such as drill breakage, bone perforation, and thermal necrosis.
• A comprehensive understanding of how drilling parameters, drill geometry, and bone material influence these forces is lacking.

Purpose of the Study:

• To investigate the impact of drilling process parameters, drill geometry, and bone material type on drilling forces (thrust force and torque).
• To identify significant drill geometry parameters and their interactions affecting drilling forces.
• To develop predictive models for drilling forces to enhance safety in robot-assisted surgeries.

Main Methods:

• Utilized three designs of experiments to analyze single-factor effects, parameter interactions, and relationships between forces and process variables.
• Investigated parameters including feed rate, spindle speed, drill diameter, web thickness, point angle, helix angle, and chisel edge angle.
• Included different bone types (bovine cortical bone and Sawbones 3401) to assess material effects.

Main Results:

• Thrust force and torque increase with higher feed rates, drill diameters, and web thicknesses.
• The influence of spindle speed and various drill angles (point, helix, chisel edge) on forces is complex and multifaceted.
• Bone type significantly impacts drilling forces, with bovine cortical bone exhibiting the highest and Sawbones 3401 the lowest.

Conclusions:

• Identified the significance of specific geometry parameters for both thrust force and torque, aiding in the development of improved surgical drills.
• Developed accurate quadratic regression equations using response surface methodology to predict drilling forces.
• These predictive models can optimize drilling conditions for robot-assisted surgeries, ensuring safer bone drilling operations.