3D Foot Alignment Measurement Using TALAS Lever Arm
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Solution Overview
Problem
Current two-dimensional radiographic methods for measuring foot-ankle alignment fail to account for the forefoot, leading to reduced precision and accuracy due to reliance on hindfoot measurements, which are rotation-dependent and poorly reproducible.
Innovation Solution
A system utilizing three-dimensional imaging to determine foot-ankle offset (FAO) through the Torque Ankle Lever Arm System (TALAS), which uses 3D coordinates of anatomical landmarks and a software program to calculate the static ankle intrinsic lever arm, providing a precise measurement of foot-ankle alignment.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If two-dimensional radiographic methods are used for measuring foot-ankle alignment, then the measurement process is simple, but the measurement precision and accuracy are reduced due to failure to account for the forefoot and rotation dependence
Solution Approach 1:
The patent transitions from two-dimensional radiographic imaging to three-dimensional imaging to measure foot-ankle alignment. This dimensional change allows comprehensive capture of both hindfoot and forefoot anatomical landmarks, eliminating the rotation dependence inherent in 2D methods and significantly improving measurement precision and accuracy.
2Reliability
If hindfoot-only measurement protocols are used, then the measurement process is simplified, but the overall measurement accuracy decreases due to geometric dependence on lower limb rotation
Solution Approach 1:
By implementing three-dimensional imaging, the system can capture anatomical landmarks of both the hindfoot and forefoot simultaneously. This eliminates the geometric dependence on lower limb rotation that plagues 2D hindfoot-only methods, thereby improving measurement reliability and reproducibility without excessive complexity.
3Measurement precision
If three-dimensional imaging is implemented, then measurement precision and accuracy are significantly improved, but the device complexity and cost increase
Solution Approach 1:
The patent employs three-dimensional imaging to capture comprehensive foot-ankle anatomical data, achieving correlation coefficients of 0.99 compared to 0.78 for 2D methods. This dimensional upgrade enables precise measurement of both hindfoot and forefoot landmarks, significantly improving diagnostic accuracy despite increased system complexity.
Solution Approach 2:
The three-dimensional imaging system serves multiple functions: it captures hindfoot alignment, forefoot alignment, and their spatial relationships simultaneously. This multi-functionality maximizes the value obtained from the imaging system, justifying the investment by providing comprehensive diagnostic information in a single scan.
Data Source
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AI summary
A system for determining the alignment measurement of the foot and ankle is disclosed. The system uses data representative of a three dimensional scanned image of a patient's foot and ankle while the patient was applying weight on the foot. Next the system detects the three dimensional coordinates associated with at least three predetermined landmarks on the patent's foot in the scanned image. A ground plane is determined using the predetermined landmarks. A center of a talar dome is determined in the scanned data. An ankle offset lever arm id determined from the set of landmarks and center of the talar dome.