Experimental study on the effect of drill quality on bone temperature in drilling

Bone drilling is widely performed in orthopedics for fixation and reconstruction of bone. In bone drilling, a hard metallic drill penetrates into the bone tissue which may cause trauma. Shear deformation of the bone material and friction between the drill and bone may induce elevated temperature in bone tissue. Temperature above a certain level may seriously harm the tissue, leading to several postoperative complications. The purpose of the current study is to measure and compare temperature in bone drilling using sharp and worn drill. Drilling tests were performed on cortical bone obtained from femoral shaft of a cow. A parametric study was conducted to quantify bone temperature using a range of drilling speeds and feed rates using drills having sharp and worn cutting edges with and without cooling environment. The temperature was measured using thermocouples, and wear of the cutting edges of the drill was measured using a scanning profilometer. Experimental results demonstrated lower temperature in bone using a sharp drill compared with a worn drill for similar drilling conditions. The bone temperature was found to rise with drill rotational speed, rate of penetration and size of the drill with and without cooling. Blunt drills were found more crucial for inducing thermal necrosis in bone.