Metaphyseal Referencing Guide for Humeral Stem-Tray Alignment
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Solution Overview
Problem
Current methods for preparing the humerus for humeral component implantation in joint replacement procedures face challenges such as implant misalignment and cortical bone impingement due to independent stem and tray placement, leading to compromised fixation.
Innovation Solution
Instruments and guides that link the implant stem axis to the proximal bowl or tray position, providing metaphyseal referencing and diaphyseal alignment, ensuring proper implant geometry and alignment through sizing and guiding tools along the humeral canal.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the metaphyseal reference technique is used to center the tray within the resection surface, then proximal fixation is improved, but misalignment between the tray and stem occurs leading to distal cortical bone impingement or distal bone voids
Solution Approach 1:
The guide instrument serves as an intermediary device that connects the metaphyseal reference point to the diaphyseal canal. The guide includes a reference surface that contacts the metaphysis and a guide feature that directs the awl into the diaphysis, ensuring that the stem and tray are aligned through the intermediate structure of the guide itself.
Solution Approach 2:
The guide combines multiple functions into a single instrument: it provides metaphyseal referencing, defines the stem axis orientation, and guides the awl into the diaphyseal canal. This merging of functions ensures that both proximal fixation and stem-tray alignment are achieved simultaneously through one integrated tool.
2Manufacturing precision
If the diaphyseal reference technique is used to prepare the stem canal first, then stem placement is improved, but the bowl or tray breaks through the proximal cortical bone compromising proximal fixation
Solution Approach 1:
The guide enables preliminary action by allowing the surgeon to establish the metaphyseal reference and visualize the stem axis orientation before actually preparing the stem canal. The guide feature directs the awl to show the intended path, allowing verification of proper alignment before committing to the canal preparation.
Solution Approach 2:
The guide acts as an intermediary that translates the metaphyseal reference point into the correct diaphyseal orientation. The guide feature serves as the mediating structure that ensures the stem canal preparation will result in proper alignment with the tray, preventing cortical bone breakthrough.
3Adaptability or versatility
If independent stem and tray placement procedures are used, then surgical flexibility is improved, but implant misalignment occurs leading to compromised fixation
Solution Approach 1:
The guide merges the previously independent stem preparation and tray placement procedures into a coordinated process. By providing a physical link between the metaphyseal reference and diaphyseal orientation, the guide ensures that both components are placed in proper alignment while maintaining surgical flexibility through the ability to adjust the guide's orientation.
Data Source
AI summary
A system for sizing the resected surface to provide metaphyseal referencing and to properly guide a tool into a central portion of the canal in the diaphysis. The system can include a sizing feature to approximate the size of the metaphysis. The system can also include a base configured to contact the metaphysis and a guide feature configured to guide a tool along a central portion of the canal in the diaphysis.