Hip Navigation Sensors for Real-Time Leg Length and Offset Tracking
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Solution Overview
Problem
Current computer-assisted navigation systems for joint replacement surgery, particularly hip replacement, face challenges in accurately measuring and maintaining leg length and offset during procedures, often requiring cumbersome pre- and post-operative scans and relying on inaccurate pelvic registration methods.
Innovation Solution
The system employs sensor units on the pelvis and femur to measure and track the positional relationship in six degrees-of-freedom, using a femoral registration tool like a surgical broach to register the femoral coordinate system, allowing for real-time calculation and conveyance of changes in leg length and offset during surgery, thereby eliminating the need for traditional pelvic registration and fixed capital equipment.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If traditional navigation systems use fixed capital equipment and pelvic registration, then they can provide navigation guidance, but they incur high capital expenditures and achieve inaccurate measurement results
Solution Approach 1:
The patent extracts the registration function from complex fixed capital equipment and pelvic registration procedures, isolating it to a simple femoral registration tool that can be inserted into the femur. This extraction eliminates the need for expensive fixed equipment while maintaining registration accuracy through direct femoral contact.
Solution Approach 2:
The patent replaces expensive, complex fixed capital equipment with inexpensive, disposable sensor units and registration tools. The femoral registration tool and sensor units can be discarded after use, eliminating the need for costly system infrastructure while providing accurate measurement capabilities.
2Measurement precision
If traditional systems require pre- and post-operative scans, then they can establish baseline measurements, but they increase loss of time and surgical complexity
Solution Approach 1:
The patent performs femoral registration during the surgical procedure itself rather than requiring pre-operative scans. The registration tool is inserted into the femur and sensor units are attached intra-operatively, establishing the femoral coordinate system at the time of surgery, which eliminates time-consuming pre- and post-operative imaging.
Solution Approach 2:
The patent maintains continuous measurement capability throughout the surgical procedure by keeping sensor units attached to the pelvis and femur throughout the operation. This continuous tracking eliminates the need for separate pre- and post-operative scans, providing uninterrupted measurement of leg length and offset changes during the procedure.
3Measurement precision
If traditional navigation systems use pelvic registration, then they can establish a reference frame, but they achieve inaccurate results due to the complexity and imprecision of pelvic mapping
Solution Approach 1:
Instead of establishing a reference frame through complex pelvic registration, the patent inverts the approach by directly registering the femur using a simple insertion tool. The femoral registration tool is inserted into the femur to establish the femoral coordinate system directly, bypassing the need for pelvic reference framing entirely.
Solution Approach 2:
The patent extracts the registration function from the pelvic reference frame and applies it directly to the femur. By using a femoral registration tool that inserts into the femur, the system eliminates the need for complex pelvic mapping and reference frame establishment, achieving registration accuracy through direct femoral contact.
4Device complexity
If the system uses sensor units on pelvis and femur with femoral registration, then it eliminates fixed capital equipment, but it requires existing surgical tools to be adapted
Solution Approach 1:
The patent makes existing surgical tools multi-functional by integrating sensor units with standard surgical instruments. The femoral registration tool can be any existing surgical instrument that can be inserted into the femur, such as a broach or reamer, allowing the system to leverage existing tooling rather than requiring specialized manufacturing.
Data Source
AI summary
The present invention generally relates to computer-assisted joint replacement surgery, and corresponding navigation systems. The systems and methods presented find particular use in performing hip replacement surgery. For example, in one embodiment, there is provided a system and method for: (a) measuring a pre-dislocation positional relationship between a patient's pelvis and the patient's femur; (b) performing a post-dislocation femoral registration of the femur; (c) tracking the position of the femur relative to the pelvis during a reduction procedure; (d) calculating a change in leg length and a change in offset, after the reduction procedure, based on the femoral registration and the pre-dislocation positional relationship between the pelvis and the femur; and (e) conveying the change in leg length and the change in offset.