Inertial Sensor Leg Length Calculation in Hip Surgery
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Solution Overview
Problem
Current methods for determining leg length discrepancy and offset in orthopedic hip surgery lack precision and accuracy, necessitating the development of a minimally invasive yet precise system for measuring these parameters during hip replacement and other procedures.
Innovation Solution
A computer-assisted surgery system utilizing inertial sensors, a caliper with a translational joint and light source, and a mechanical gauge to establish a pelvic coordinate system, track instrument orientation, and calculate leg length discrepancy and offset by comparing preoperative and post-implant rejointing conditions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If traditional measurement methods are used for leg length discrepancy and offset, then the surgical procedure is simple, but the measurement precision and accuracy are insufficient
Solution Approach 1:
The patent combines multiple measurement functions (leg length discrepancy and offset measurements) into a single integrated computer-assisted surgery system. The system merges inertial sensor units, coordinate system modules, tracking modules, and geometric calculation modules into one unified platform, allowing simultaneous acquisition of multiple parameters through coordinated operation of interconnected components rather than separate measurement devices
Solution Approach 2:
The patent replaces traditional mechanical measurement methods with an inertial sensor-based system. Instead of using purely mechanical gauges and physical alignment tools, the system employs inertial sensors to detect orientation and position, with computer algorithms calculating leg length discrepancy and offset from the collected data, thereby substituting mechanical measurement with sensor-based detection and computational analysis
2Ease of operation
If minimally invasive measurement methods are used, then patient trauma is reduced, but measurement accuracy may be compromised
Solution Approach 1:
The patent uses inertial sensor units as intermediary devices that can be attached to external instruments rather than requiring direct intrusion into the surgical site. The sensors act as mediators between the surgical instruments and the measurement system, capturing orientation and position data without compromising the minimally invasive nature of the procedure while maintaining measurement accuracy through computational geometry
Solution Approach 2:
The system creates a virtual model of the anatomical structures by tracking instrument positions and orientations relative to the pelvic coordinate system. Instead of directly measuring bone structures, the system copies the geometric relationships through sensor data and computational reconstruction, allowing accurate measurement of leg length discrepancy and offset without physical intervention in the surgical field
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
The system provides precise and accurate measurements of leg length discrepancy and offset, enabling improved surgical outcomes, post-operative gait assessment, and potential corrective actions during hip replacement surgeries.
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
Implementation Method 2
the at least one instrument supports a light source emitting a light beam that is perpendicular relative to a direction of the translational joint
Data Source
AI summary
A computer-assisted surgery system has inertial sensor unit connected to an instrument and producing readings representative of its orientation. A computer-assisted surgery processor unit has a coordinate system module for setting a pelvic coordinate system from readings of the inertial sensor unit when the instrument is in a given orientation relative to the pelvis, a tracking module for tracking an orientation of the instrument relative to the pelvic coordinate system during movements thereof and a geometrical relation data module for recording preoperatively a landmark orientation relative to the pelvic coordinate system and a distance when the at least one instrument has a first end abutted to a pelvic landmark and a second end abutted to a leg landmark, for recording after implant rejointing the medio-lateral orientation and the distance, and for calculating a leg length discrepancy and/or an offset, based on the distances and the medio-lateral orientations.