Hip Surgery CAS System Pelvic Reference Alignment
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Solution Overview
Problem
Current methods for measuring intraoperative limb length discrepancy and medio-lateral offset in hip replacement surgery lack precision, relying heavily on surgeon skill and are prone to measurement errors due to leg repositioning challenges, which can lead to postoperative complications such as leg length inequality, discomfort, and unstable hip joints.
Innovation Solution
A computer-assisted surgery system that digitizes frames of reference for the pelvis and femur, using trackable references and a sensor apparatus to calculate and adjust surgical parameters, ensuring accurate measurement and alignment of hip joint implants during surgery.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If surgeons manually align the leg along the vertical axis for measurement, then measurements can be obtained, but measurement precision deteriorates due to dependence on surgeon skill and leg repositioning errors
Solution Approach 1:
The patent replaces manual mechanical alignment and measurement methods with a computer-assisted system using trackable references, sensor apparatus, and digital frame of reference alignment. The system automatically calculates surgical parameters based on tracked positions, eliminating the need for manual leg repositioning and measurement by the surgeon.
Solution Approach 2:
The patent creates a digital copy of the patient's anatomy through frame of reference digitization and tracking. Virtual models and digital representations of the pelvis and femur are used to calculate measurements, replacing physical manual measurement processes and allowing precise parameter determination without repeated physical repositioning.
2Measurement precision
If repeated leg repositioning is performed for accurate measurement, then measurement accuracy improves, but surgical time increases
Solution Approach 1:
The patent performs preliminary digitization of frame of references and establishes trackable references on the pelvis and femur before implant reduction. This preliminary setup allows subsequent measurements to be obtained automatically without repeated repositioning, as the system can calculate parameters from the pre-established digital models and tracking data.
Solution Approach 2:
The computer-assisted system replaces the time-consuming manual process of repeated leg repositioning and measurement with automated calculation based on tracked positions. The sensor apparatus continuously monitors positions, and the controller automatically computes surgical parameters, eliminating the need for multiple manual alignment attempts.
3Reliability
If manual measurement methods are used, then device complexity remains low, but reliability of surgical outcomes deteriorates due to measurement errors
Solution Approach 1:
The patent replaces simple manual measurement tools with a comprehensive computer-assisted system including trackable references, sensor apparatus, and controller. This complex system provides reliable, automated calculation of surgical parameters, eliminating human error and improving the reliability of surgical outcomes despite the increased device complexity.
Solution Approach 2:
The system creates accurate digital copies and virtual models of the patient's anatomy, allowing precise measurement and planning. These digital representations enable reliable calculation of surgical parameters without the errors associated with manual measurement, justifying the increased system complexity through significant improvements in measurement reliability.
Data Source
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AI summary
A CAS system (50) and method (100) for measuring surgical parameters during hip replacement surgery to guide an operator (S) in inserting a hip joint implant in a femur, comprising a first trackable reference (56) in fixed relation with the pelvis and a registration tool (56). A sensor apparatus (54) tracks the first trackable reference (56) and the registration tool (56). A controller unit (52) is connected to the sensor apparatus (54) so as to receive tracking data for the first trackable reference (56) and the registration tool (56). The controller unit (52) has a position and orientation calculator (202) to calculate from the tracking data a position and orientation of the pelvic trackable reference (56) to track the pelvic frame of reference, and of the registration tool (56) to produce a femoral frame of reference at two sequential operative steps. A reference orientation adjustor (204) receives tracking data for the pelvic frame of reference, and the femoral frame of reference associated with the first trackable reference (56), to orient the femoral frame of reference in a reference orientation with respect to the pelvic frame of reference, and to produce a reference adjustment value as a function of the reference orientation. A surgical parameter calculator (206) receives tracking data from the registration tool (56) to calculate surgical parameters as a function of the reference adjustment value, the surgical parameters at the two sequential operative steps being related by the reference orientation.