Limb Evaluation Apparatus for Objective Joint Stability Measurement
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Solution Overview
Problem
Current methods for diagnosing and treating ligament damage in the knee lack accuracy and objectivity, relying on subjective manual tests that are difficult to perform and quantify, leading to potential misdiagnosis and inadequate treatment.
Innovation Solution
A limb and joint measurement apparatus that applies torque to the lower leg and monitors movement in six degrees of freedom, providing objective data on joint range of motion, stability, and compliance, while accommodating individual patient alignment and natural variances.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If manual tests (Lachman's test, Pivot Shift test, Anterior Drawer Test) are used to evaluate ligament damage, then the evaluation can be performed with simple equipment, but the measurement precision and objectivity are poor due to clinician subjectivity
Solution Approach 1:
The patent replaces manual mechanical testing with an automated mechanical measurement system that applies controlled forces and measures joint response objectively. The apparatus uses motors, force sensors, and motion capture systems to eliminate clinician subjectivity while maintaining mechanical testing principles.
Solution Approach 2:
The measurement apparatus is designed to evaluate multiple ligaments (ACL, PCL, MCL, LCL) and multiple degrees of freedom (anterior-posterior, medial-lateral, rotational movements) using a single integrated system, providing comprehensive joint assessment rather than requiring separate manual tests for each ligament.
2Reliability
If subjective manual evaluation is used to assess joint play and ligament compliance, then the operation is simple and quick, but the reliability and reproducibility of diagnosis are poor
Solution Approach 1:
The system incorporates real-time feedback through force sensors and motion capture that continuously monitor joint response during testing. The computer-controlled system adjusts applied forces based on measured joint stiffness and compliance, providing objective data that improves diagnostic reliability while automating the complex measurement process.
Solution Approach 2:
The apparatus performs self-calibration and automated data analysis, reducing the need for highly skilled operators. The system automatically processes measurement data, generates compliance curves, and provides diagnostic recommendations, making reliable measurement more accessible.
3Adaptability or versatility
If standardized testing protocols are used for all patients, then the testing procedure is simple and consistent, but the adaptability to individual patient alignment and anatomy is poor
Solution Approach 1:
The apparatus features adjustable components including movable rails, adjustable force application points, and configurable measurement parameters that can be dynamically adapted to each patient's anatomy. The system can modify testing protocols in real-time based on individual joint characteristics and injury patterns.
Solution Approach 2:
The system applies forces and measurements at specific locations tailored to each patient's anatomy and injury pattern. Different force magnitudes, directions, and measurement parameters can be applied to different joints and ligaments based on individual needs rather than using uniform testing for all patients.
Data Source
AI summary
A method and apparatus for reliably positioning a 3-segment limb, such as a leg or arm for imaging and medical analysis, which can accommodate for the patient's “natural alignment”. The apparatus positions the limb in such a way that the position of the proximal segment is controlled while an known external torque is applied at a known rate to the distal segment. The location of each of the limb's three segments is recorded using either external or internal measurement techniques, and the relative motions between the proximal and intermediate segments are used in the orthopedic evaluation of the proximal joint. Furthermore, the relative motions between the intermediate and distal segments are used in the orthopedic evaluation of the distal joint. By applying a known torque at a known rate, clinicians will be provided with valuable information related to joint range of motion, stability, laxity, and compliance.