Acetabulum Rim Digitizer for Pelvic Orientation Tracking
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Solution Overview
Problem
Current methods for determining pelvic tilt in hip surgery, such as optical navigation and C-arm validation, are invasive, costly, and do not provide real-time quantitative assessment, while manual jigs fail to account for patient positioning, leading to potential inaccuracies in acetabular cup orientation.
Innovation Solution
A computer-assisted surgery system utilizing an acetabulum rim digitizer with an inertial sensor unit, a coordinate system module, and a tracking module to set and track the pelvic coordinate system, allowing for precise determination of pelvic tilt and orientation using inertial sensors, which are cost-effective and provide real-time data without external references.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If optical navigation is used to determine pelvic tilt, then measurement precision is improved, but device complexity and invasiveness increase due to navigation systems and pinning references
Solution Approach 1:
The patent extracts the essential function of orientation measurement from complex optical navigation systems and implements it using a standalone inertial sensor unit with accelerometer and gyroscope. This removes the need for external navigation infrastructure, pinning references, and complex optical tracking equipment while maintaining the core capability of determining pelvic tilt and cup orientation.
Solution Approach 2:
The patent replaces the mechanical and optical navigation system with an inertial sensing system that uses accelerometers and gyroscopes to measure orientation. This substitution eliminates the need for external optical references, pinning procedures, and complex navigation hardware, achieving the same measurement precision through purely inertial means.
2Measurement precision
If C-arm validation is used for cup positioning assessment, then measurement capability is improved, but device complexity and cost increase due to bulky equipment
Solution Approach 1:
The patent extracts the orientation measurement function from bulky C-arm equipment and implements it in a compact inertial sensor unit attached to the impactor. This provides real-time cup positioning assessment without requiring large imaging equipment in the operating room.
Solution Approach 2:
The patent replaces the mechanical C-arm imaging system with an inertial sensing system that directly measures orientation through accelerometers and gyroscopes. This substitution eliminates the need for bulky imaging equipment while providing equivalent or superior real-time orientation data.
3Ease of operation
If manual jigs are used for cup positioning, then ease of operation is improved, but measurement precision deteriorates because patient position on operative table is not accounted for
Solution Approach 1:
The inertial sensor unit on the impactor autonomously measures its own orientation relative to gravity and the patient's anatomy. The system self-calibrates by detecting the pelvic coordinate system through specific impactor positions, eliminating the need for external reference systems or complex setup procedures while maintaining high measurement precision.
Solution Approach 2:
The patent changes the reference frame from the operative table (which manual jigs use) to the patient's pelvic anatomy by using inertial sensors to detect gravity-relative orientation. This parameter change allows the system to automatically adapt to any patient positioning on the table while maintaining accurate cup orientation measurement.
4Productivity
If inertial sensors are used for pelvic tilt determination, then cost-effectiveness and real-time data provision are improved, but measurement precision may deteriorate compared to optical navigation
Solution Approach 1:
The patent merges the accelerometer and gyroscope into a single integrated inertial sensor unit that processes both linear acceleration and angular velocity data. This combination allows the system to compute orientation through integration of gyroscope data and correct drift using accelerometer gravity reference, achieving high precision real-time measurement that neither sensor could achieve alone.
Solution Approach 2:
The system continuously monitors orientation data from the inertial sensors and provides real-time feedback to the surgeon through the user interface. The feedback mechanism allows dynamic adjustment and verification of measurements during the procedure, ensuring high precision while maintaining real-time operation.
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 and cost-effective determination of pelvic tilt and acetabular cup orientation, reducing the risk of improper positioning and enhancing the precision of hip arthroplasty procedures by providing real-time orientation data during surgery.
Implementation Method 1
at least one inertial sensor unit connected to the at least one instrument, the inertial sensor unit producing readings representative of its orientation
Data Source
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AI summary
A computer-assisted surgery (CAS) system for tracking an orientation of a pelvis comprises at least one instrument, the instrument having an acetabulum abutment end adapted to be received in an acetabulum, a rim abutment adapted to be abutted against a rim of the acetabulum, and an indicator representative of a physical orientation of the instrument. An inertial sensor unit is connected to the at least one instrument, the inertial sensor unit producing readings representative of its orientation. A computer-assisted surgery processor unit comprises a coordinate system module for setting a pelvic coordinate system from readings of the at least one inertial sensor unit when the at least one instrument has the acetabulum abutment end received in the acetabulum, the coordinate system module setting the pelvic coordinate system by obtaining a plurality of orientation values from the at least one inertial sensor unit when the rim abutment is abutted against locations of the rim, one of said orientation values having the indicator aligned with a reference landmark, the coordinate system module defining an acetabular plane representative of the pelvic coordinate system from the plurality of orientation values; and a tracking module for tracking an orientation of the at least one inertial sensor unit relative to the pelvic coordinate system during movements thereof using the readings from the inertial sensor unit. An interface outputs orientation data as a function of the pelvic coordinate system.