Elbow Prosthesis Guiding Tool for Humeral Axis Alignment
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Solution Overview
Problem
Current methods for implanting the humeral component of an elbow prosthesis rely on empirical determination of the joint axis, leading to inaccurate positioning of the artificial trochlea relative to anatomical and prosthesis surfaces, resulting in suboptimal functional outcomes.
Innovation Solution
An ancillary tool is developed to precisely determine the axis of bend of the joint using a guiding tool with a stirrup element and drill/punch system, allowing for precise positioning of the artificial trochlea by boring along the geometric axis and using a pin as a reference for subsequent measurements and component placement, with optional features like hollow screws, templates, and trial trochleas for accurate sizing and alignment.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If empirical determination of the joint axis is used, then the implantation process is simple, but the positioning precision of the artificial trochlea deteriorates
Solution Approach 1:
The patent applies preliminary action by first determining the exact geometric position of the joint axis and inserting a reference pin along this axis before proceeding with the implantation. The guiding tool with stirrup element is positioned on the trochlea to define a guiding zone for drilling along the axis of bend, establishing a precise reference framework in advance that ensures accurate positioning of the artificial trochlea while maintaining procedural simplicity
Solution Approach 2:
The patent introduces intermediary elements including a guiding tool with stirrup element that attaches to the trochlea, a reference pin inserted along the determined joint axis, and a template for positioning. These intermediaries serve as mediators between the surgeon and the implantation process, providing physical references that translate the geometric axis determination into precise component positioning without complicating the overall procedure
2Manufacturing precision
If a guiding tool with stirrup element and pin insertion is used, then the positioning precision of the artificial trochlea is improved, but the device complexity increases
Solution Approach 1:
The guiding tool is designed with multi-functionality to reduce overall device complexity. The stirrup element can attach to the trochlea and work with different drilling tools, the same tool can be used for both determining the joint axis and guiding the drill, and the template can accommodate different pin positions. This universality allows a single guiding tool design to handle multiple positioning requirements without proportionally increasing complexity
Solution Approach 2:
The guiding tool is segmented into distinct functional components: the stirrup element that attaches to the trochlea, the guiding zone definition mechanism, and the template for positioning. This segmentation allows each component to be optimized independently and facilitates easier manufacturing and assembly while maintaining the overall precision function of the complete guiding system
Data Source
AI summary
An ancillary tool for fitting a humeral component of a total or partial elbow prosthesis, comprising a guiding tool (30) for boring a humeral trochlea (T) along a geometric axis (X-X′) of bend of a joint to be equipped with said prosthesis. The guiding tool (30) includes a stirrup element (31) and means (32b, 33b) for securing said stirrup element on the humeral trochlea (T) so that said guiding tool defines a guiding zone that is aligned in the geometric axis of bend for the introduction (F1) of a drill (40), a punch or the like, in the humeral trochlea (T) along said geometric axis of bend. This ancillary tool also comprises at least one stepped template (701, 702, 703) for determining an anterior offset of said geometric axis of bend (X-X′) with respect to a humeral diaphyseal axis (Y-Y′).