Effect of Rotational-Vibrational Drill in Bone Drilling to Decrease of Thermal Necrosis (An Animal Study)

Internal immobilization of fractured parts of bone depends on the drilling of fracture site and screw fixation of implanted devices to the bone. During bone drilling، the temperature could increase above 47°C and causes irreversible thermal necrosis. This study is concerned with ultrasonic assisted drilling of bone to determine the best processing condition to minimize the osteonecrosis. Drilling tests were performed with ultrasonic assisted drilling on the femur of bovine and increase of temperature in drilling site was measured. The results demonstrate that in ultrasonic assisted drilling، decrease of machining forces in cutting speed of 1000 rpm leads to decrease of local temperature raise in drilling site rather than other conventional drilling process. Furthermore، in rotational speed of 2000 rpm، the temperature of drill site is independent than feed rate. It is found that by applying ultrasonic vibration in feed direction of drill bit، the temperature elevation and thermal necrosis can be reduced in comparison to conventional and high speed drilling and because of the lack of dependence on the feed rate applicable to the surgery.