Vertebral Fixation Rod Bending With Robotic Surgical Feedback
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Solution Overview
Problem
Existing methods for shaping vertebral fixation rods during spinal fusion surgery are prone to inaccuracies due to manual bending and require additional imaging, which exposes patients and staff to radiation, and do not account for varying vertebral heights and deformities, especially in scoliotic patients.
Innovation Solution
A robotic system uses preoperative and intraoperative data to control a rod-bending apparatus, employing plungers or milling tools to shape the rod accurately, with optional thinning modules to adjust flexibility, based on surgical plans and real-time feedback.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If manual bending tools are used to shape the rod during surgery, then the surgeon can adjust the rod to fit the vertebrae, but the procedure is prone to inaccuracies and requires considerable force
Solution Approach 1:
The patent replaces manual mechanical bending with a robotic system that uses image-guided positioning and controlled mechanical actuators to shape the rod. The robotic system translates the desired rod geometry (derived from preoperative imaging and surgical planning) into precise mechanical bending actions, eliminating the need for manual force application while improving positioning accuracy.
Solution Approach 2:
The patent performs rod shaping before the rod is inserted into the patient's body. The robotic system pre-bends the rod to match the target geometry calculated from imaging data, so that when the rod is inserted, it requires minimal additional adjustment. This preliminary action reduces the complexity and inaccuracy of intraoperative manual bending.
2Manufacturing precision
If additional intraoperative imaging is performed to determine rod shape, then the rod can be accurately shaped to match screw positions, but the patient and staff are exposed to additional radiation
Solution Approach 1:
The patent performs all necessary imaging (CT or MRI scans) before surgery to obtain three-dimensional images of the spine. The rod geometry is calculated from these preoperative images, and the rod is shaped accordingly before insertion. This eliminates the need for additional intraoperative imaging to determine rod shape, thereby avoiding extra radiation exposure to the patient and staff.
Solution Approach 2:
The patent creates a digital model (virtual copy) of the patient's spine from preoperative imaging data. The desired rod geometry is derived from this digital model, which accurately represents the anatomical structures and screw positions. This virtual copying approach eliminates the need for physical re-imaging during surgery while maintaining high precision in rod shaping.
3Stability of the object's composition
If a single rigid rod is used to connect multiple vertebrae, then all vertebrae are rigidly connected, but this does not allow preservation of relative motion in vertebrae that should not be fused
Solution Approach 1:
The patent applies different compliance characteristics to different segments of the same rod. By varying the rod's cross-sectional properties (such as thickness or material composition) at specific locations, the rod can provide rigid support where fusion is required while maintaining flexibility where natural motion should be preserved. This local differentiation allows the rod to simultaneously satisfy both stability and adaptability requirements.
Solution Approach 2:
The patent designs the rod with variable compliance along its length, allowing it to dynamically adapt to the mechanical requirements of different spinal segments. The rod transitions from rigid sections (for fused vertebrae) to more compliant sections (for mobile vertebrae), enabling the structure to provide appropriate mechanical response at each location based on the surgical requirements.
Data Source
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.