Constant Force Spring Caliper for Orthopedic Measurement
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Solution Overview
Problem
Conventional calipers used in orthopedics for measuring knee and leg dimensions often apply inconsistent pressure due to human error, leading to inaccurate measurements and discomfort, especially with irregularly shaped condyles and varying soft tissue amounts, resulting in inferior knee brace customization.
Innovation Solution
A caliper with constant force springs that apply a consistent, predetermined force of 2 lbs. throughout its extension and retraction, featuring flat condyle contact and an ergonomic design with slidable jaws and contoured outer peripheries for easy alignment and pressure distribution, ensuring uniform measurements across different knee phenotypes and soft tissue amounts.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional calipers are used with manual jaw adjustment, then the device is simple to manufacture, but the compression force is inconsistent leading to measurement errors
Solution Approach 1:
The caliper uses a spring-loaded mechanism that automatically applies consistent compression force when the jaws contact the condyles. The spring is pre-loaded to provide a predetermined force (e.g., 2 lbs) without requiring manual adjustment by the clinician, making the system self-regulating and eliminating human error in force application.
Solution Approach 2:
The invention changes the force parameter from variable (manual adjustment) to constant (pre-loaded spring). The spring mechanism maintains a predetermined compression force throughout the measurement process, ensuring consistent pressure regardless of the clinician's technique or the patient's anatomy.
2Adaptability or versatility
If narrow jaws are used to fit irregular condyle shapes, then the caliper can adapt to different anatomies, but the jaws shift over soft tissue causing discomfort and inaccurate measurements
Solution Approach 1:
The caliper jaws are designed with contoured, curved surfaces that match the natural geometry of the condyles. This curvature allows the jaws to conform to irregular anatomical shapes while distributing pressure evenly across the bony prominences, preventing tissue pinching and discomfort.
Solution Approach 2:
The jaws have different surface characteristics at different locations: the contact surfaces are contoured to match condyle geometry, while the gripping portions have textured surfaces for clinician control. This localized differentiation optimizes both anatomical adaptation and user control.
3Ease of operation
If elongated straight jaws are used for measurement, then the structure is simple, but there is little space between soft tissue areas for clinician adjustment
Solution Approach 1:
The jaws are designed with a three-dimensional contoured shape rather than simple straight elongated forms. This adds spatial dimensionality that creates clearance between the jaw surfaces and surrounding soft tissue, allowing clinician fingers to access and adjust the measurement position comfortably.
4Area of stationary object
If cup-shaped contact points are used to extend over condyles, then coverage is improved, but clinician placement control is limited
Solution Approach 1:
The caliper allows dynamic adjustment of the jaw position along the longitudinal axis after initial placement. The clinician can slide the jaws forward or backward to optimize contact with the condyles, providing both extensive coverage and precise placement control.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The caliper provides consistent and accurate measurements by ensuring consistent compression and comfortable application, reducing human error and improving the customization of knee braces across a range of anatomical variations.
Implementation Method 1
The caliper has a constant force spring that creates consistent, predetermined force throughout its extension and retraction
Data Source
AI summary
A caliper is arranged for applying predetermined constant pressure to a joint or other anatomy under measurement. The caliper includes an elongate housing, a first jaw connected to the housing, a second jaw slidably connected to the housing, the first and second jaws spaced apart by a predetermined minimum distance, and a constant force spring engaging the first and second jaws. The constant force spring biases the first and second jaws toward one another. A method includes using the caliper to measure anatomical dimensions.