Lower-Limb Length Discrepancy Measurement via Femoral Axis Alignment
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Solution Overview
Problem
Conventional methods for measuring leg length discrepancy (LLD) in orthopedic joint replacement surgery are unreliable and do not account for the full length of the leg, leading to inaccurate pre-operative and intra-operative assessments.
Innovation Solution
A method involving the use of patient bone data from medical imaging to identify anatomical landmarks, align femoral mechanical axes with a pelvic axis, and calculate LLD based on distances between distal landmarks, displayed on a screen for pre-operative planning and intra-operative verification.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional methods for measuring leg length discrepancy are used, then the measurement process is simple, but the measurement precision is poor and does not account for full leg length
Solution Approach 1:
The patent replaces manual mechanical measurement methods with a computer-based system that uses medical imaging data (X-rays, CT scans, or MRIs) to automatically calculate leg length discrepancy. The system processes digital images, identifies anatomical landmarks, and computes precise measurements, eliminating the need for physical tape measures or manual positioning while achieving superior measurement precision.
Solution Approach 2:
The patent introduces medical imaging data as an intermediary medium between the physical leg and the measurement system. By capturing anatomical structures through X-rays, CT scans, or MRIs, the system obtains detailed bone geometry information that serves as a foundation for accurate LLD calculation, enabling precise measurement without direct physical contact with the patient's limbs.
2Reliability
If conventional measurement methods are used, then the equipment required is minimal, but the reliability of the measurement is insufficient for surgical planning
Solution Approach 1:
The patent performs preliminary actions by acquiring and processing medical imaging data before surgical planning. The system pre-processes X-ray, CT, or MRI images to extract anatomical landmark coordinates and bone geometry information, creating a digital model that can be reliably used for LLD calculation and surgical simulation without requiring complex intraoperative measurements.
Solution Approach 2:
The patent creates a digital copy of the patient's skeletal anatomy through medical imaging. This virtual replica allows repeated, precise measurements of leg length and alignment without repeating physical measurements, enabling reliable LLD assessment and surgical planning while reducing measurement variability and improving reproducibility.
3Measurement precision
If manual measurement methods are used during surgery, then the process is quick, but the accuracy does not account for full leg length and anatomical variations
Solution Approach 1:
The patent performs all complex measurement and calculation actions in advance during the preoperative phase. By processing medical imaging data beforehand to establish accurate LLD values and surgical plans, the system eliminates the need for time-consuming intraoperative measurements, allowing surgeons to proceed directly to the surgical procedure with pre-calculated guidance.
Solution Approach 2:
The patent replaces time-consuming manual measurement procedures with automated computer-based calculation systems that process digital imaging data. This substitution dramatically reduces measurement time while improving precision by using digital image processing rather than manual visual estimation or physical measurement tools during the surgical procedure.
Data Source
AI summary
A method of calculating leg length discrepancy of a patient including: receiving patient bone data associated with a lower body of the patient; identifying anatomical landmarks in the patient bone data; orienting a first proximal landmark and a second proximal landmark relative to each other and an origin in a coordinate system; aligning a first axis associated with a first femur and a second axis associated with a second femur with a longitudinal axis extending in a distal-proximal direction, wherein the first and second distal landmarks are adjusted according to the alignment of the first and second axes; calculating a distance between the first and second distal landmarks in the distal-proximal direction along the longitudinal axis; and displaying at least one of the distance or a portion of the patient bone data on a display screen.