Wrist Implant Articulating Surfaces for Dart-Thrower Motion
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Solution Overview
Problem
Conventional wrist arthroplasty devices fail to accurately replicate the complex motion of the dart-thrower's arc, essential for various daily and sporting activities, due to their design limitations that restrict non-planar motions and lead to instability and wear.
Innovation Solution
A wrist implant system with distal and proximal components featuring articulating portions with concave and convex surfaces, designed to mimic the midcarpal joint, allowing physiological motions like the dart-thrower's motion while constraining non-physiological ones, and incorporating a modular bearing surface to preserve the natural joint's shape and function.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional wrist arthroplasty devices with simple articulating surfaces are used, then manufacturing is easier and device complexity is reduced, but the device cannot accurately replicate complex dart-thrower's arc motion, leading to instability and wear
Solution Approach 1:
The patent employs doubly curved articulating surfaces with specific radii of curvature (e.g., first radius in range 3-15mm, second radius in range 10-30mm) that are not equal to each other, creating an ellipsoidal or spheroidal geometry. This curved surface design enables the implant to replicate the complex dart-thrower's arc motion while maintaining stability and reducing wear, resolving the contradiction between reliability and device complexity.
2Adaptability or versatility
If conventional planar motion constraints are applied, then non-physiological motion is constrained, but physiological dart-thrower's arc motion is also restricted, reducing functional outcomes
Solution Approach 1:
The patent designs the articulating surfaces with specific geometric parameters (radii of curvature, surface profiles) that dynamically adapt to different motion planes. The surfaces are configured to permit physiological dart-thrower's arc motion while constraining non-physiological motion through their inherent geometric constraints, allowing the joint to transition smoothly between different motion states while maintaining stability.
3Duration of action of stationary object
If modular bearing surfaces with specific curvature ratios are used, then wear is reduced and longevity is improved, but manufacturing precision requirements increase
Solution Approach 1:
The patent specifies precise parameter ranges for the articulating surfaces, including radius of curvature ratios (e.g., second radius 10-30mm versus first radius 3-15mm), surface profile dimensions, and geometric relationships. These parameter specifications enable modular bearing surfaces that reduce wear and improve longevity while providing clear manufacturing targets that balance precision requirements with fabricability.
Data Source
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AI summary
An implant system and apparatus configured to permit motion of the wrist in at least one physiological direction, as well as in a dart thrower's motion, and constrain motion of the wrist in at least one non-physiological direction are provided. The implant according to one embodiment includes a distal component and proximal component. Each of the distal and proximal components includes a primary articulating portion and a secondary articulating portion. Primary and secondary articulating portions include at least one component having either a substantially convex or a substantially concave shape. The secondary articulating portion is configured to be radially and volarly disposed in relation to the primary articulating portion.