Trial Instrument Plane Guide for Orthopaedic Joint Positioning
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Solution Overview
Problem
The challenge in orthopaedic joint replacement surgery is accurately positioning and preparing the bone to fit the selected prosthesis components relative to anatomical features, which affects the fit and articulation of the joint prosthesis.
Innovation Solution
A trial instrument assembly comprising a trial implant with a guide portion and a plane guide that engages the trial implant to assess its position relative to anatomical features, allowing for precise alignment and selection of appropriate prosthesis components based on dimensions such as length, width, and offset.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a trial implant is inserted into a prepared bone cavity to check fit, then the fit of the prosthesis component can be assessed, but the position of the trial implant relative to anatomical features cannot be determined
Solution Approach 1:
A plane guide acts as an intermediary element between the trial implant and the anatomical features. The plane guide engages with the trial implant through a projection-recess assembly and extends beyond it to provide visual reference against anatomical landmarks, thereby mediating the measurement of the trial implant's position relative to these features
Solution Approach 2:
The solution adds a new dimensional element by extending the plane guide beyond the trial implant in a direction perpendicular to the implant's longitudinal axis. This creates an additional reference plane that allows assessment of position in multiple dimensions (apical-distal, medial-lateral, and proximal-distal orientations) rather than only checking fit within the cavity
2Adaptability or versatility
If multiple trial implants of different sizes are used to find the best fit, then appropriate prosthesis components can be selected, but the process becomes more complex and time-consuming
Solution Approach 1:
The plane guide is designed as a universal tool that can be used with trial implants of different sizes. The projection-recess assembly provides a standardized interface that accommodates various trial implant dimensions, allowing the same plane guide to serve multiple functions across different implant size selections without requiring separate measurement tools for each size
3Ease of manufacture
If the trial implant is designed with fixed dimensions, then manufacturing is simplified, but it cannot accommodate variations in patient anatomy
Solution Approach 1:
The trial implant is segmented into two distinct parts: a body portion that fits within the prepared bone cavity and a guide portion that protrudes from the cavity. This segmentation allows the body portion to be manufactured in standard sizes while the guide portion provides adjustable positioning capabilities through the plane guide interface, thus balancing manufacturing simplicity with anatomical adaptability
Data Source
AI summary
A trial instrument assembly for use in a surgical procedure to replace an orthopaedic joint includes a trial implant having a stem portion for fitting within a prepared cavity in the patient's bone. The stem portion defines a stem axis. A neck portion is connected to the stem portion to protrude from the cavity when the stem portion is within the cavity. The assembly includes a plane guide that extends from the neck portion in a plane that is selected from (i) a plane perpendicular to the stem axis, and (ii) a plane parallel to the stem axis, for use in determining the location of the trial implant relative to an anatomical feature in a direction measured along the stem axis or perpendicular to the stem axis, respectively.