Trajectory Guide for Rigid Pedicle Screw Placement
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Solution Overview
Problem
Current spinal fixation systems face challenges in accurately placing pedicle screws with minimal radiation exposure and high precision, as existing advanced systems are expensive, cumbersome, and prone to human error, leading to potential nerve damage and prolonged radiation exposure for both patients and surgeons.
Innovation Solution
A guidance system comprising a trajectory guide that restricts instruments to a selected path and a movable support to align and fix the guide in place, reducing the need for prolonged radiation exposure by allowing precise alignment and fixation outside the patient's body, thereby minimizing the risk of misalignment and nerve damage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If advanced image-guided systems (StealthStation, FluoroNav) are used to determine proper screw trajectory, then measurement precision and reliability are improved, but device complexity and cost increase significantly
Solution Approach 1:
The system divides the guidance function into two segments: (1) pre-operative CT-based 3D planning that determines the optimal trajectory, and (2) intra-operative physical template guidance that executes the planned trajectory. This segmentation eliminates the need for complex, expensive real-time image-guided systems while maintaining high precision through the use of a custom-fabricated template that mechanically constrains the drill and screw to the pre-planned path.
Solution Approach 2:
The system creates a physical copy (3D-printed template) of the patient-specific anatomy and pre-planned trajectory from the CT scan data. This physical template serves as a direct replica guide that translates the virtual planning into precise physical execution without requiring complex real-time imaging systems, thereby reducing device complexity while maintaining measurement precision.
2Device complexity
If manual landmark recognition and trajectory approximation are used, then device complexity is reduced, but manufacturing precision and reliability deteriorate due to human error
Solution Approach 1:
The template is designed to be self-aligning and self-guiding. It features anatomical landmarks and guide channels that automatically position the drill and screw along the correct trajectory without requiring the surgeon to manually recognize landmarks or approximate angles. The template's physical geometry enforces the precise trajectory, eliminating human error while keeping the device relatively simple.
3Measurement precision
If prolonged fluoroscopy is used to monitor screw advancement, then measurement precision is improved, but harmful radiation exposure increases for both patient and surgeon
Solution Approach 1:
The optimal screw trajectory is determined in advance through CT-based 3D planning before the surgery begins. The physical template is fabricated based on this pre-planned trajectory, encoding the precise path into its geometry. During surgery, the template mechanically guides the drill and screw along this pre-determined path, eliminating the need for prolonged intra-operative fluoroscopy to verify trajectory, thereby reducing radiation exposure while maintaining precision.
4Ease of operation
If pedicle screws are placed without rigid trajectory guidance, then ease of operation is improved, but reliability deteriorates due to potential misalignment and nerve damage
Solution Approach 1:
The physical template acts as an intermediary device between the surgeon's drilling action and the pedicle bone. It features guide channels and stopping mechanisms that passively constrain the drill and screw to the correct trajectory and depth. This intermediary structure provides reliable, fail-safe guidance that prevents misalignment and nerve damage while requiring minimal skill or complexity from the surgeon, thus maintaining ease of operation.
Data Source
AI summary
A system for guiding an implant to an optimal placement within a patient includes a trajectory guide for guiding instruments along a selected trajectory and a trajectory fixation device for fixing the trajectory guide in a selected position. The trajectory guide defines a path configured to align with the selected trajectory. A movable support mounts the trajectory guide and selectively moves the trajectory guide to align the trajectory guide with the selected trajectory prior to fixing the trajectory guide in the selected position. After fixing the trajectory guide, instruments can be inserted along the trajectory through the path defined by the trajectory guide.