ABSTRACT
INTRODUCTION: The performance of the drilling process depends on the characteristics of the drilling equipment and surgeon's skill. To our knowledge, no research has focused on multi-parameter analysis of the dynamic behaviour of drills during the drilling process. This study aimed to characterise the physical changes and effects of different drills attached to a robotic arm during drilling of artificial bones in a standardised experimental setup. MATERIAL AND METHODS: Drilling processes using three brands of drills attached to a robotic arm were compared in terms of thrust force, vibration, noise level, speed deviation, and temperature. A standardised experimental setup was constructed, and measurement data were analysed statistically. Identical artificial bones were drilled 10 times with each drill. RESULTS: Thrust force measurements, which varied through the cortex and medulla, showed expressive differences for each drill for maximum and mean values (p<0.001). Meaningful differences were obtained for mean vibration values and noise level (p<0.001). Speed variation measurements in drilling showed conspicuous differences with confident statistics (p<0.001). Induced temperature values were measured statistically for Drill 1, Drill 2, and Drill 3 as 78.38±11.49°C, 78.11±7.79°C, and 89.77±7.79°C, respectively. CONCLUSION: Thrust force and drill bit temperature were strongly correlated for each drill. Vibration values and noise level, which also had an influential relationship, were in the acceptable range for all experiments. Both thrust force and speed deviation information could be used to detect the drill bit status in the bone while drilling.
ABSTRACT
PURPOSE: To compare stability after anterior instrumentation alone versus modified combined anterior and posterior instrumentation for burst fractures of the thoracolumbar spine in calves. METHODS: Thoracolumbar spines of 10 calves were used. An axial compression force was applied on each specimen using a material-testing machine, until there was a burst fracture at T12 or L1. Five specimens were fixed with anterior instrumentation alone, using 2 rods connected by 2 screws above and 2 screws below the fractured vertebra plus one tranverse connector. Another 5 were fixed with our modified technique of combined anterior and posterior instrumentation. This entailed one rod connected with one screw above and one screw below the fractured vertebra anteriorly, and another rod connected with one transpedicular screw above and one transpedicular screw below the fractured vertebra posteriorly. After instrumentation, the experiment was conducted again on each specimen and the compressive stiffness and vertebral height loss between the 2 groups compared. RESULTS: The mean compressive stiffness was significantly greater after modified combined anterior and posterior instrumentation than anterior instrumentation alone (5508 vs 2888 N, p=0.0256), whereas the respective vertebral height losses were 37 and 33 mm (p=0.3808). CONCLUSION: Our modified technique of combined anterior and posterior instrumentation provides greater stability than traditional anterior instrumentation alone.
