Osteotomy Guidance Using Knee Laxity Tracking for Alignment Correction
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Solution Overview
Problem
Osteotomy procedures for correcting limb misalignment are complex and prone to over- or under-correction due to uncertainties in diagnosing and planning the procedure, particularly because of joint laxity and soft tissue influence, which current navigation systems do not adequately account for.
Innovation Solution
A system using trackers on the tibia and femur, coupled with a control unit, to track and adjust for joint laxity and soft tissue influence, allowing precise determination and monitoring of surgical plans for osteotomy, including mechanical constraints to simulate standing alignment.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If intraoperative X-ray images are acquired to guide the surgical procedure, then the alignment can be monitored, but the patient is exposed to large doses of X-rays and the procedure becomes lengthy
Solution Approach 1:
The patent replaces the X-ray imaging system with a optical/mechanical tracking system using trackers attached to the femur and tibia. The localization system uses cameras or other non-ionizing radiation detectors to track the position and orientation of bone segments in real-time, eliminating the need for repeated X-ray exposures while maintaining measurement precision.
Solution Approach 2:
The patent creates a virtual model (copy) of the patient's lower limb and surgical plan that can be viewed and manipulated on the navigation station display. This virtual copy allows the surgeon to monitor alignment and test different surgical scenarios without exposing the patient to additional radiation.
2Measurement precision
If multiple surgical gestures and intraoperative checks are performed to achieve satisfactory alignment, then the alignment accuracy is improved, but the osteotomy procedure becomes lengthy and complex
Solution Approach 1:
The patent performs preoperative planning and simulation to determine the optimal osteotomy parameters before surgery. The surgical plan is calculated in advance based on the desired postoperative alignment, allowing the surgeon to execute a single precise surgical gesture rather than performing multiple iterative corrections during the operation.
Solution Approach 2:
The navigation system provides real-time feedback on the position and orientation of the bone segments during surgery. This immediate feedback allows the surgeon to verify the correctness of the surgical gesture and make minor adjustments if needed, reducing the need for multiple iterative corrections and shortening the overall procedure time.
3Duration of action of moving object
If the surgical plan is based on preoperative 2D X-ray images, then the planning can be done in advance, but the alignment measurements have uncertainties due to differences between standing and lying positions
Solution Approach 1:
The patent changes the measurement parameters from 2D X-ray images to 3D spatial coordinates obtained by tracking the position and orientation of trackers attached to the bone segments. This allows for more precise measurement of alignment parameters that are independent of the patient's position (standing or lying), as the tracking system can compensate for gravitational effects and soft tissue deformation.
Data Source
AI summary
The present disclosure relates to a system for guiding an osteotomy procedure on a tibia and/or a femur pertaining to a patient's lower limb to correct a misalignment of said lower limb, wherein a tibial tracker is fixed to the tibia and a femoral tracker is fixed to the femur, said system comprising a control unit configured to be coupled to a localization system adapted to track a position and orientation of the tibial tracker and the femoral tracker, wherein the control unit is configured to: —receive at least one target alignment parameter of the lower limb provided by a user; —determine a position of a set of characteristic points on the tibia and/or the femur relative to the tibial tracker and/or the femoral tracker; —track the positions of said characteristic points relative to the tibial tracker and/or the femoral tracker based on localization data of the set of characteristic points during application of mechanical constraints by the user onto the patient's knee, said tracked positions forming a knee measurement data set; —based on the knee measurement data set, adjust a function defining a model of the patient's knee; —based on at least one output of said function and on at least one alignment parameter of the lower limb in the constrained position, determine at least one correction parameter of the osteotomy procedure to be applied to the lower limb to achieve the target alignment parameter.