Inertial Sensor Positioning Block for Bone Alteration Tracking
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Solution Overview
Problem
Current computer-assisted surgery systems face challenges with the size and visibility requirements of tracking systems, particularly in orthopedic surgeries, where miniaturized technologies providing fewer than 6 degrees of freedom are lacking, leading to inaccuracies and difficulties in integrating tracking devices into surgical instruments.
Innovation Solution
A computer-assisted surgery system utilizing a positioning block with an inertial sensor unit providing orientation data for at least two degrees of freedom, allowing adjustable orientation and integration with a processing system to calculate bone alteration parameters, and a caliper with inertial sensors for precise dimension measurement.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If traditional optical tracking systems with multiple light sources are used, then six degrees of freedom tracking precision is achieved, but the device size becomes large and obstructive
Solution Approach 1:
The patent replaces the mechanical/optical tracking system with an electromagnetic tracking system. Instead of using multiple physical light sources arranged in specific geometries, the invention uses electromagnetic fields generated by coils to achieve tracking functionality. This substitution eliminates the need for large physical structures while maintaining tracking precision through field-based measurement.
Solution Approach 2:
The patent changes the fundamental tracking parameter from optical detection of physical light sources to electromagnetic field detection. By measuring electromagnetic field characteristics (such as phase and amplitude variations) instead of detecting physical light positions, the system achieves accurate tracking without requiring large physical trackable references, thus resolving the contradiction between precision and size.
2Reliability
If active transmitters with power sources are used for tracking, then signal transmission capability is improved, but the complexity of wiring and power management increases
Solution Approach 1:
The tracking system operates passively by detecting electromagnetic fields without requiring active transmitters or power sources on the tracked objects. The system uses the inherent electromagnetic properties of materials and environmental fields, eliminating the need for batteries, wiring, or power management components on the tracked instruments or patient anatomy.
Solution Approach 2:
The patent introduces electromagnetic fields as an intermediary medium for tracking. Instead of direct electrical connections or active signal transmission between components, the system uses electromagnetic field interactions to convey positional and orientational information, thereby simplifying the overall system architecture and eliminating complex wiring requirements.
3Device complexity
If optical elements are used for passive tracking, then no power source is required, but line of sight visibility between sensor and elements must be maintained
Solution Approach 1:
The patent replaces the optical line-of-sight tracking system with an electromagnetic tracking system. Electromagnetic fields can penetrate through tissues and materials that would block optical paths, allowing tracking without direct visibility. This substitution maintains the passive operation advantage while eliminating the line-of-sight constraint.
4Ease of manufacture
If electromagnetic tracking devices are used, then integration with surgical instruments is simplified, but distortions from orthopedic instruments may cause accuracy loss
Solution Approach 1:
The patent applies electromagnetic tracking at multiple localized positions on the surgical instrument and patient anatomy. By placing electromagnetic sensors and reference markers at specific strategic locations, the system can locally compensate for distortions caused by metallic instruments. The local electromagnetic field measurements allow for correction of instrument-induced distortions while maintaining overall tracking accuracy.
Data Source
AI summary
A computer-assisted surgery system for guiding alterations to a bone, comprises a trackable member secured to the bone. The trackable member has a first inertial sensor unit producing orientation-based data. A positioning block is secured to the bone, and is adjustable once the positioning block is secured to the bone to be used to guide tools in altering the bone. The positioning block has a second inertial sensor unit producing orientation-based data. A processing system providing an orientation reference associating the bone to the trackable member comprises a signal interpreter for determining an orientation of the trackable member and of the positioning block. A parameter calculator calculates alteration parameters related to an actual orientation of the positioning block with respect to the bone.