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, cemented or cementless fixation, which limits their effectiveness and durability.
Innovation Solution
A modular elbow replacement system with a humeral and ulnar component design that allows for intraoperative selection of linked or unlinked constraints and cemented or cementless fixation, featuring a humeral stem and condyle components with distally extending portions that shift the contact point outwardly during varus/valgus rotation, enabling adjustable soft tissue tension and enhanced stability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a fixed constraint design (linked or unlinked) is used in elbow replacement, then the implant structure is simple, but the adaptability to different patient needs and intraoperative observations is poor
Solution Approach 1:
The elbow replacement implant is divided into separate modular components: a humeral component and an ulnar component that can be independently selected and assembled. This segmentation allows surgeons to choose between linked and unlinked constraint configurations based on patient-specific needs and intraoperative findings, resolving the contradiction between adaptability and complexity by making the system configurable through modular assembly rather than fixed design
Solution Approach 2:
The modular component system is designed to perform multiple functions: it can be configured as either a linked constraint (with axial connection) or an unlinked constraint (without axial connection) elbow replacement. This multi-functionality allows a single set of modular components to address different clinical scenarios, improving adaptability while maintaining reasonable device complexity through standardized component interfaces
2Reliability
If polyethylene bushings are used in linked elbow replacement, then mechanical constraint is provided, but wear and deformation occur causing osteolysis and requiring revision surgery
Solution Approach 1:
The harmful polyethylene bushings that cause wear and osteolysis are extracted from the linked elbow replacement design. Instead of using polyethylene bushings as the constraint mechanism, the invention employs a direct metallic connection between humeral and ulnar components through axial engagement, eliminating the source of wear particles while maintaining mechanical constraint and improving long-term reliability
3Force
If the contact point between humeral and ulnar components is fixed, then the implant structure is simple, but the restoring moment during varus/valgus motion is insufficient
Solution Approach 1:
The articular surfaces of the humeral and ulnar components are designed with specific curved geometries that cause the contact point to migrate outwardly during varus and valgus motion. This curvature design generates an increased restoring moment that enhances joint stability, resolving the contradiction between force generation and structural simplicity by incorporating optimized surface geometry rather than adding mechanical complexity
Data Source
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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.