Pelvic Digitizer with Inertial Sensor for Hip Surgery
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Solution Overview
Problem
Conventional computer-assisted surgery systems for orthopedic implant procedures, such as total hip replacement, face challenges with inaccurate alignment due to 'eyeballing' methods and limitations of optical or magnetic tracking systems, including high costs, limited range, and electromagnetic interferences.
Innovation Solution
A pelvic digitizer device equipped with self-contained inertial sensors that creates a pelvic frame of reference by using a tool with a preset inertial sensor unit, visual guide, and adjustable stopper to accurately align with bone landmarks, allowing for precise tracking without signal transmission or electromagnetic interference.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If optical or magnetic tracking systems are used for computer-assisted surgery, then accurate tracking of patient coordinate system is achieved, but high costs, limited operating range, and electromagnetic interferences occur
Solution Approach 1:
The patent replaces optical and magnetic tracking systems with inertial sensors that use mechanical motion detection (accelerometers, gyroscopes) to track pelvic orientation. This substitution eliminates electromagnetic interference while maintaining tracking accuracy through self-contained inertial measurement units that operate independently of external electromagnetic fields.
Solution Approach 2:
The patent introduces an intermediary coordinate transformation system that maps inertial sensor data to patient-specific anatomical coordinate systems. This intermediary layer processes raw inertial measurements and transforms them into clinically relevant orientation data, enabling accurate tracking without direct reliance on electromagnetic or optical fields.
2Ease of operation
If conventional 'eyeballing' methods are used for implant positioning, then surgical simplicity is maintained, but inaccurate alignment of implant components occurs
Solution Approach 1:
The system enables surgeons to perform self-guided alignment by providing real-time inertial feedback about tool orientation relative to the pelvic coordinate system. The surgeon uses the inertial sensor data to autonomously achieve accurate implant positioning without requiring complex external tracking infrastructure or specialized expertise in coordinate transformation.
Solution Approach 2:
The patent implements feedback by continuously monitoring inertial sensor measurements and providing real-time information about tool orientation and pelvic position. This feedback loop allows surgeons to adjust implant positioning dynamically based on quantitative orientation data, transforming subjective visual estimation into objective, measured alignment.
3Reliability
If inertial sensors are used for tracking, then immunity to electromagnetic disturbances is achieved, but device complexity increases
Solution Approach 1:
The patent merges multiple inertial sensors (accelerometers, gyroscopes) and coordinate transformation algorithms into an integrated pelvic digitizer device. This consolidation combines the complexity of inertial measurement, coordinate system registration, and real-time tracking into a single unified system, reducing the overall system complexity compared to distributed optical or magnetic tracking infrastructure.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
Enables accurate alignment and tracking of orthopedic implants, reducing implant wear and failure by providing a reliable, cost-effective, and interference-immune solution for precise pelvic navigation during surgery.
Implementation Method 1
The sensor unit has a preset orientation such that tracking about at least one axis is known when the sensor unit is initialized
Data Source
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AI summary
A pelvic digitizer device comprises a body comprising: a shaft having a tooling end and a handle end with a handle for being manipulated. A visual guide is oriented in a reference plane of the digitizer device. A cup is connected to the tooling end and adapted to be received in an acetabulum of a patient. An inertial sensor unit is connected to the body, the inertial sensor unit having a preset orientation aligned with the reference plane.