A novel acoustic emission screwdriver reduces surgeons´ cancellous screw stripping rate - A biomechanical study

Orthopedic surgeons refine their torque sensitive skills from tightening cancellous screws. Still, experienced surgeons exhibit surprisingly high screw stripping rates in osteopenic cancellous bone. Whether Acoustic-Emission technology, detecting energy waves from microstructural damage during screw purchase, can reduce these rates is unclear. Our aim was to evaluate if surgeons, irrespective of their experience, reduced cancellous screw stripping rate by combining their skills with feedback from an innovative Acoustic-Emission screwdriver.

Thirteen orthopedic surgeons with 0-23 years´ experience inserted 468 large fragment cancellous screws through plates into synthetic osteoporotic bone. The 1st stage, surgeons tightened 9 screws each without Acoustic-Emission feedback. The 2nd stage, each tightened 18 screws using the Acoustic-Emission feedback modified screwdriver. The last stage, surgeons tightened 9 screws each, again without Acoustic-Emission feedback. A strain gauge on the screwdriver was used to verify screw stripping.

Surgeons stripped 36 out of 115 screws (31 %) in stage 1, 37 out of 227 screws (16 %) in stage 2, and 26 out of 114 screws (23 %) in stage 3. A significant reduced screw stripping rate was found in stage 2 compared to in stage 1 (p < 0.001). Neither the individual surgeon nor experience of the surgeon contributed to screw stripping probability in a mixed effect logistical regression model.

Acoustic-Emission technology is superior to the torque sensitive skills of surgeons, demonstrating its potential to assist surgeons in real time, regardless of their experience, in reducing screw stripping rates in cancellous bone.