Experimental evaluating and statistical modeling of temperature elevation in bone drilling with internal cooling with gas

Bone fracture occurs as a result of accident, old age and disease. Generally bone fracture treatment consists of stabilizing the fractured bone in the right position. In complex fractures, stabilizing internal and external tools and equipment is used to stabilize the fractured bone in position. Bone drilling is required in order to connect fixating devices. The forces required for chip formation, increase the temperature during bone drilling. The phenomenon of thermal necrosis of the bone occurs if the temperature exceeds 47 degrees Celsius. Thermal necrosis inhibit bone fixation and causes the wrong bone healing. The current study has been trying to examine the effect of the cooling gas on the reduction of temperature rise on drilling site as well as statistical analysis of the process. Tests have been carried out using direct injection of nitrogen gas using internal coolant drill bits. Using cooling gas reduced the increase in drilling temperature to 15 degrees Celsius and prevented the thermal necrosis. The maximum increase in temperature in conventional drilling was 56 degrees Celsius, while using cooling gas the increase in temperature of 43 degrees Celsius was achieved. This reduces the risk of thermal necrosis. Statistical analysis also indicates that in the drilling with direct cooling with nitrogen gas the temperature changes are almost independent of the rotational speed.