Experimental temperature evaluation during a robotized bone drilling process

A serious problem associated with orthopedic bone drilling manipulation is the so-called thermal osteonecrosis (TO). This problem occurs because the drilling manipulation generates heat, and the amount of heat depends on the drilling conditions. This work presents the experimental evaluation of the temperature during automated bone drilling by using a handheld Orthopedic bone Drilling Robot ODRO. Up to now, such experimental results related to temperature evaluation in bone drilling by robots have not been presented. Fresh porcine and bovine femur bones were specimens in the experiments. The increase in bone temperature during drilling was measured by a thermal infrared camera. Thermographic sequence images were recorded, processed and visualized using specialized software, which allows to capture accurately the moment of drill bit penetration through the bone and its extraction when going back to initial position. The results showed that under given feed rate and drill speed, when using a new drill bit, the temperature value during porcine femur drilling exceeded the critical threshold of 50 degrees C for less than 2 s, and thermal osteonecrosis does not occur. When using a worn-out drill bit, the temperature value during bovine femur drilling significantly exceeded the threshold of 50 degrees C, and thermal osteonecrosis occurs. Thus, to guarantee bone drilling without the risk of thermal osteonecrosis, the automated drilling should be executed with the simultaneous control of speed of drill bit and feed rate. This is possible to be achieved only by robotic execution of the manipulation.