Experimental study on biological damage in bone in vibrational drilling

BACKGROUND: Drilling is a well-known mechanical operation performed for fixing fracture at required locations in bone. The process may produce mechanical and thermal alterations in the structure of the bone and surrounding tissues leading to irreversible damage known as osteonecrosis. OBJECTIVE: The main purpose of this study was to measure the level of biological damage in bone when a drill assisted by low and high levels of vibrations is penetrated into bone tissue. METHODS: Histopathology examination of sections of bones has been performed after drilling the bone using a range of vibrational frequency and rotational speed imposed on the drill with and without supply of saline for cooling. RESULTS: Cell damage in bone was caused by the combined effect of drill speed and frequency of vibrations. Histopathology examination revealed more damage to bone cells when a frequency higher than 20 kHz was used in the absence of cooling. Cooling the drilling region helped minimize cell damage more at a shallow depth of drilling compared to deep drilling in the cortex of cortical bone. The contribution of cooling in minimizing cell damage was higher with a lower drill speed and frequency compared to a higher drill speed and frequency. CONCLUSION: Vibrational drilling using a lower drill speed and frequency below 25 kHz in the presence of cooling was found to be favorable for safe and efficient drilling in bone.