Vertebral Fixation Rod Shaping for Robotic Spinal Surgery
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Solution Overview
Problem
Current methods for shaping vertebral fixation rods in spinal fusion surgery are prone to inaccuracies due to manual bending and require additional imaging, which can expose patients and staff to radiation, and do not account for varying spinal deformities and dynamic stability needs.
Innovation Solution
A robotic system that uses preoperative image data to shape the rod in real-time, with feedback from intraoperative deviations, employing motorized plungers to bend and thin the rod according to the positions of pedicle screw heads, allowing for precise three-dimensional shaping and variable compliance along the rod's length.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If manual bending tools are used to shape the rod during surgery, then the rod can be adapted to match the spine curvature, but the surgeon must exert considerable force and the procedure is prone to inaccuracies
Solution Approach 1:
The rod is pre-shaped using a rod bender device before surgery to match the specific curvature requirements. The device allows the rod to be pre-bent to the desired shape based on patient-specific spinal anatomy, eliminating the need for difficult intraoperative bending while ensuring accurate positioning.
Solution Approach 2:
A rod bender device serves as an intermediary tool between the surgeon's intent and the rod shaping process. This specialized device provides mechanical advantage and precision control, allowing accurate rod shaping without requiring the surgeon to directly apply considerable force with standard pliers.
2Manufacturing precision
If additional intraoperative imaging is performed to determine rod shape, then accurate positioning can be achieved, but radiation exposure to patient and staff increases
Solution Approach 1:
Rod shaping is performed preoperatively using the rod bender device based on preoperative imaging and planning. This eliminates the need for additional intraoperative imaging to determine rod shape, as the rod is already shaped to match the planned configuration before the patient is exposed to radiation during surgery.
Solution Approach 2:
The rod shaping process is extracted from the intraoperative setting and performed separately before surgery. By removing the shaping step from the surgical procedure, the need for additional intraoperative imaging is eliminated, thereby reducing radiation exposure while maintaining accuracy.
3Stability of the object's composition
If a rigid rod is used to connect multiple vertebrae, then all vertebrae are firmly stabilized, but natural spinal motion and flexibility are lost
Solution Approach 1:
The rod is designed with varying cross-sectional properties along its length, creating regions of different stiffness. This allows the rod to provide rigid stabilization at fusion levels while maintaining flexibility and allowing motion at non-fusion levels, matching the local mechanical requirements of different spinal segments.
Solution Approach 2:
The rod transitions from a static, uniformly rigid structure to a dynamic structure with variable compliance. By incorporating sections with different rigidity, the rod can adapt its mechanical response to different spinal levels, providing stability where needed while preserving natural motion elsewhere.
Data Source
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AI summary
A system for rod bending for use in robotic spinal surgery, enabling the correct bending of a fusion rod to match the shape required to accurately pass through the heads of the pedicle screws. The system uses data generated by information provided to the robot by the surgeon's preoperative plan, optionally augmented by feedback from the robot control system of deviations encountered intraoperatively. Such deviations could occur, for example, when the surgeon decides intraoperatively on a different trajectory or even to skip screws on one vertebra, in which case, the robot will be commanded to perform the alternative procedure, with commensurate instructions relayed to the control system of the rod-bending machine. The system is also able to thin down the rod at predetermined locations along its length, adapted to be at selected intervertebral locations, for maintaining limited flexibility between vertebrae, instead of fixating them.