Development And Application Of Intelligent Planning System Assisted By Surgical Navigation For Pedicle Screw Placement

Minimally invasive,digital,and intelligent surgery symbolizes modern spine surgery and the future development direction of spine surgery.Intelligent planning of pedicle screws is the critical technology for fully automated robotic surgery in the future.Intelligent planning is to realize automatic recognition of the target vertebral body and intelligently plan the trajectory,specification,placement depth,and other parameters of the pedicle screw according to the bone mass,morphology,and injury types of different vertebral bodies.Previous studies have proved that CT value has a linear relationship with bone mineral density.The association between BMD and Young’s modulus of bone tissue was exponential.Therefore,placing the pedicle screw in a position where the pull-out strength is as high as possible and the CT value of the screw trajectory is as high as possible may be another idea for pedicle screw placement for osteoporotic vertebrae.With the development of computer technology,more powerful computers and better algorithms have been developed to automate planning.They are possible to use preoperative or intraoperative CT to find a trajectory that meets the criteria for pedicle screw placement and passes the maximum CT value.In this study,we first proposed an automatic pedicle screw planning method based on CT values for patients with osteoporosis.We evaluated the difference between this method and manually planned screw trajectory positions and CT values on CT images of 10 patients with lumbar degeneration.The results showed that the recommended screw diameters and lengths obtained by automatic planning were conservative.In the CT of patients with lumbar degeneration,the screw placement point based on automated planning is more outward-downward than manual planning.The trajectory has a larger caudal angle and a smaller abduction angle.The average CT value of automatic planned trajectory is 29.13%higher than that of manual trajectory planning,which is expected to improve the pull-out force of osteoporotic pedicle screws.Then,to verify whether the increase of trajectory CT value can increase the pull-out force of pedicle screws,an in vitro osteoporosis model was established.Biomechanical tests were performed to verify the safety and effectiveness of the automatic pedicle screw planning system based on the CT value of this model.An in vitro osteoporosis model showed that automated pedicle screw trajectory planning based on CT values did not result in pedicle screw breakage.The higher pull-out force of the screw was obtained by automatic planned trajectory,which increased by 44.7% compared with manual planned trajectory and achieved a similar pull-out force size to that of normal manual planned trajectory.This method may be a valuable new method for pedicle screw placement in osteoporotic vertebrae.Finally,we verified whether conventional CT could achieve similar planning results as micro-CT and investigated the safety,convenience,and effectiveness of using opticalelectromagnetic integrated navigation combined with an automatic planning system to assist pedicle screw placement.The results show that conventional CT can replace micro-CT for automated planning.Automatic planning combined with surgical navigation enables accurate and rapid pedicle screw placement.The trajectory of conventional CT planning can achieve biomechanical properties similar to micro-CT planning and is a potential alternative technique for posterior spinal fixation without additional implants.This study proposes an automated spinal pedicle screw planning method with less manual involvement.It demonstrates the potential for using pedicle screw placement combined with surgical navigation,promising to provide a new method for enhancing pedicle screw fixation strength without additional implants.