Pedicle Screw Trajectory Planning Using Patient-Specific Bone Density
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Solution Overview
Problem
Existing methods for determining the screw trajectory of a pedicle bone screw do not adequately consider patient-specific bone properties, particularly bone density, leading to potential complications such as loosening, especially in cases of low bone mineral density.
Innovation Solution
A method that involves obtaining a CT image of the target bone area, establishing a three-dimensional geometric model with bone density information, accessing a database with bone screw insertion and pedicle traversing surfaces, morphing the model to match the patient's bone, and calculating an optimal screw trajectory that maximizes bone density, while ensuring the screw does not perforate the bone structure.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If conventional methods are used to determine screw trajectory, then the process is simple, but the fixation performance is suboptimal because screw parameters are not optimized based on patient-specific bone density
Solution Approach 1:
The patent performs preliminary actions by creating a three-dimensional geometric model of the patient's bone and a three-dimensional bone density model before screw insertion. This pre-planning allows optimization of screw trajectory and parameters based on actual bone density distribution, ensuring optimal fixation performance before the actual surgical procedure
Solution Approach 2:
The patent creates a digital copy (three-dimensional geometric model) of the patient's actual bone structure from CT images. This virtual model allows for simulation and optimization of screw trajectories without affecting the actual patient, enabling preliminary testing and optimization of fixation strategies
2Reliability
If screw trajectory is optimized based on bone density, then fixation performance improves, but the calculation complexity increases
Solution Approach 1:
The patent applies local quality by considering the spatial distribution of bone density in different regions of the bone. Instead of using a uniform approach, the screw trajectory is optimized based on the specific bone density characteristics at each location along the potential trajectory, allowing the screw path to adapt to local bone quality variations for improved reliability
Solution Approach 2:
The patent changes parameters by optimizing screw trajectory based on bone density values. The system evaluates multiple potential trajectories and selects the optimal one by analyzing bone density parameters along each path, adjusting the trajectory parameters to maximize fixation reliability based on the measured bone density distribution
3Measurement precision
If three-dimensional bone density modeling is implemented, then screw placement accuracy improves, but data processing requirements increase
Solution Approach 1:
The patent segments the bone structure into a three-dimensional grid or voxel-based model, where each element contains bone density information. This segmentation allows for precise measurement of bone density at multiple locations and enables accurate determination of optimal screw trajectories by evaluating density values at discrete points along potential paths
Data Source
AI summary
A method for determining the screw trajectory of a pedicle bone screw comprises: obtaining a CT image of the target bone area intended to receive the pedicle bone screw, establishing an individualized three-dimensional geometric model of the target bone area based on the CT image, accessing a database comprising a three-dimensional bone area model; wherein the bone area model comprises a bone screw insertion surface and a pedicle traversing surface for each pedicle, morphing the bone area model to the geometric model of the target bone area generating a morphed vertebra model with a bone screw insertion surface and the pedicle traversing surface, calculating a maximum of bone density when the bone material is replaced by a bone screw for a bone screw in the morphed vertebra model of the target bone, and outputting the space vector of the screw trajectory for the bone screw together with the length and diameter of the bone screw in the morphed vertebra model of the target bone.