Modular Elbow Implant Intraoperative Constraint Selection
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Solution Overview
Problem
Current elbow replacement devices lack the ability to intraoperatively adjust soft tissue tension and provide mechanical constraint for varus/valgus motion, and they do not allow for the selection of linked or unlinked constraints or cemented/cementless fixation, leading to limitations in restoring joint function and stability.
Innovation Solution
A modular elbow replacement system that allows surgeons to select between linked or unlinked constraints and cemented or cementless fixation, featuring a humeral and ulnar component design with adjustable articular surfaces that shift contact points during varus/valgus motion, enabling intraoperative adjustment of soft tissue tension and constraint.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If unlinked elbow replacement is used to preserve soft tissue integrity, then soft tissue function is maintained, but joint stability and control during varus/valgus motion are insufficient
Solution Approach 1:
The articular surface is designed with variable curvature that dynamically adapts during varus/valgus motion. The contact point automatically shifts between central and peripheral regions based on the degree of rotation, providing progressive mechanical constraint that enhances joint stability while preserving soft tissue function.
Solution Approach 2:
The curvature radius of the articular surface changes as a parameter during varus/valgus rotation. This parameter change causes the contact point to migrate outwardly, increasing the restoring moment and providing progressive constraint without requiring linked mechanical connection.
2Stability of the object's composition
If linked elbow replacement is used to provide mechanical constraint, then joint stability is improved, but soft tissue tension cannot be adjusted and ligamentous integrity is compromised
Solution Approach 1:
The dynamic articular surface design allows the implant to adapt its constraint characteristics during motion. The contact point migration provides progressive constraint that can be tuned by selecting different curvature profiles, allowing optimization of joint stability while preserving soft tissue tension and integrity.
3Ease of manufacture
If fixed curvature articular surface is used, then manufacturing is simplified, but contact point cannot shift outwardly during varus/valgus motion to increase restoring moment
Solution Approach 1:
The articular surface incorporates controlled variations in curvature radius as a design parameter. This parameter variation enables the contact point to migrate outwardly during varus/valgus motion, increasing the restoring moment and mechanical constraint while remaining manufacturable through precision molding or machining processes.
4Device complexity
If non-modular elbow replacement is used, then device complexity is reduced, but inability to select different constraints or fixation types limits clinical applicability
Solution Approach 1:
The elbow replacement system is divided into modular components including the humeral component, ulnar component, and interchangeable articular surfaces. This segmentation allows surgeons to select different constraint types (unlinked or linked) and fixation methods (cemented or cementless) by combining different modules, providing clinical versatility without significantly increasing overall system complexity.
Data Source
AI summary
Apparatus and methods for total elbow replacement are provided to allow a surgeon to intraoperatively select a linked or unlinked constraint by utilizing a connection located on the body of the ulnar and/or humeral stem. Additional modularity also allows the selection of a cemented or cementless stem as described herein. The modularity and adjustability provides a number of advantages.