Orthopedic Hinge Assembly with Interchangeable Gear Profiles
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Solution Overview
Problem
Existing knee brace hinges are either complex and expensive or limited in control and movement, failing to accurately simulate anatomical knee motion and apply necessary loads for injury healing.
Innovation Solution
A hinge assembly with interchangeable gear profiles that allow for complex, non-linear motion paths, enabling anatomical motion simulation and load application through the interaction of teeth on first and second gears, providing robust control and simpler design compared to prior art.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If traditional 4-bar hinges are used to produce natural knee movement, then anatomical motion simulation is improved, but device complexity increases significantly
Solution Approach 1:
The hinge is segmented into two separate hinge arms (first hinge arm and second hinge arm) that can independently rotate relative to each other. This segmentation allows each arm to be designed with simpler geometry while collectively achieving the complex anatomical motion path through their relative movements, rather than requiring a complex monolithic 4-bar linkage structure.
Solution Approach 2:
The hinge employs dynamic motion characteristics where the motion path is not fixed but varies based on the interaction between the two hinge arms. The first hinge arm rotates about a first axis and the second hinge arm rotates about a second axis, creating a dynamic motion path that naturally simulates anatomical knee movement without requiring complex mechanical linkages.
2Ease of manufacture
If geared hinges are used for robust construction and easy manufacturing, then ease of manufacture and reliability are improved, but motion control versatility deteriorates
Solution Approach 1:
The hinge allows for parameter changes in the motion path by varying the rotational axes, radii, and angular ranges of the two hinge arms. This enables the same basic two-arm structure to produce different motion characteristics suitable for various anatomical conditions and rehabilitation stages, providing versatility without requiring complex geared mechanisms.
Solution Approach 2:
The two-arm hinge structure serves multiple functions: it provides robust mechanical support, enables complex anatomical motion simulation, allows for adjustable motion parameters, and maintains ease of manufacture. This universal design replaces the need for specialized geared mechanisms while achieving superior adaptability for different clinical applications.
3Reliability
If complex hinges are designed to provide robust control and anatomical motion, then motion control and anatomical accuracy are improved, but device complexity and cost increase
Solution Approach 1:
By segmenting the hinge into two independently rotating arms with distinct rotational axes, the design achieves robust motion control through the interaction of these simple components. Each arm can be manufactured with basic precision, yet their combined movement provides reliable control over the complex anatomical motion path, avoiding the need for complex single-unit hinges.
Solution Approach 2:
The hinge merges the rotational movements of two simple hinge arms to produce the complex anatomical motion trajectory. This combining of simple rotational motions achieves the same effect as complex mechanical linkages but with greater reliability and simpler construction, as each component has a single well-defined function.
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 hinge assembly effectively mimics anatomical knee motion and applies therapeutic loads, offering robust control and versatility in design while being easier to manufacture and maintain than traditional systems.
Implementation Method 1
A first gear is defined on the first hinge arm, and a second gear is defined on the second hinge arm. The second teeth of the second gear are arranged to interact with the first teeth of the first gear.
Data Source
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AI summary
A method (100) includes selecting a defined motion path (27) of a hinge assembly (3) comprising a first hinge arm (5) including a first gear (19) having a first plurality of teeth (21), and a second hinge arm (7) including a second gear (23) having a second plurality of teeth (25) arranged to interact with the first teeth (21). The method (100) involves determining a first profile of the first gear (19) and a second profile of the second gear (23) based on the defined motion path (27), which includes a variable translation of the second hinge arm (7). The method (100) involves connecting the first hinge arm (5) to the second hinge arm (7) such that as the second hinge arm (7) rotates the interaction between the first and second teeth (21, 25) along the first and second profiles translates the second hinge arm (7) along the defined motion path (27).