Hip Knee ROM Measurement Device with Coplanar Arms
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Solution Overview
Problem
Current clinical apparatuses are inadequate for simultaneously measuring the range of motion of hip and knee joints, requiring multiple assessors and lacking accuracy in tests like active and passive knee extension tests, and straight leg raise techniques.
Innovation Solution
A hip knee range of motion measurement device with coplanar movable arms, adjustable joints, and dials that allow for simultaneous measurement of hip and knee joint angles, enabling stabilization of the hip joint and precise measurement of popliteal angles by a single assessor.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If multiple assessors are used to perform knee extension tests with manual stabilization, then the hip joint can be stabilized in a certain degree of flexion, but the device complexity increases and measurement precision decreases due to human error
Solution Approach 1:
The device is divided into separate functional modules: a stabilizing component that holds the hip joint at a fixed angle, a goniometer for measuring knee flexion angle, and a protractor for measuring hip flexion angle. Each module independently performs its measurement function, eliminating the need for multiple assessors while maintaining measurement accuracy.
Solution Approach 2:
The patent introduces a mechanical intermediary device that physically connects and stabilizes the hip joint at a predetermined angle during knee extension tests. This intermediary apparatus serves as a mediator between the patient's body and the measurement instruments, providing consistent stabilization without requiring human assessors to manually hold positions.
2Reliability
If manual stabilization and measurement techniques are used, then the tests can be performed with existing simple tools, but the reliability of measurements decreases due to inconsistent stabilization and placement
Solution Approach 1:
The device pre-establishes the hip joint at a specific flexion angle (e.g., 90 degrees) using a stabilizing component with adjustable positioning mechanisms before the knee extension test begins. This preliminary setup ensures consistent starting conditions for each test, eliminating variability introduced by manual stabilization and improving measurement reliability.
Solution Approach 2:
The patent incorporates adjustable parameters in the stabilizing component, allowing the hip joint to be positioned at different predetermined flexion angles (not just 90 degrees). This capability to change parameters while maintaining stability improves reliability across different test protocols and patient conditions.
3Ease of operation
If a single assessor performs both stabilization and measurement, then the process is simpler, but accurate simultaneous measurement of hip and knee angles becomes difficult
Solution Approach 1:
The device merges multiple measurement functions into a single integrated apparatus: the stabilizing component maintains hip position while the goniometer measures knee flexion angle and the protractor measures hip flexion angle simultaneously. This combination allows one assessor to operate all components without compromising measurement precision, as the device automatically maintains proper alignment and stabilization.
Data Source
AI summary
A hip knee range of motion measurement device includes a first movable arm, a second movable arm connected to the first movable arm via a first joint, and a third movable arm connected to the second movable arm via a second joint. The device further includes a first dial attached to the second movable arm and a second dial attached to the third movable arm, each configured to measure a joint angle of the patient. The first movable arm remains longitudinally oriented with a horizontal axis of a pelvis of a patient, the second movable arm remains in axial alignment to a horizontal axis of a femur of the patient, and the third movable arm remains in axial alignment to a horizontal axis of a tibia of the patient.