Implant Trial Head With Asymmetric O-Ring Groove for Taper Removal
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Solution Overview
Problem
Existing implant trial heads struggle to balance secure attachment to femoral stem implants via friction while allowing easy removal without damaging the taper, necessitating a design that prevents accidental dislodgement and minimizes force required for detachment.
Innovation Solution
An asymmetric groove and O-ring configuration in the trial head, where the O-ring expands laterally to facilitate easy insertion and contracts for a tight fit during removal, ensuring secure coupling and easy detachment without damaging the taper.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the trial head is held on by friction to prevent accidental dislodgement, then the reliability of the connection is improved, but the force required to remove the trial head increases and may damage the taper
Solution Approach 1:
The groove is divided into two distinct portions: a first portion with a first wall angle and a second portion with a second wall angle. This segmentation allows the O-ring to experience different frictional forces during insertion versus removal, resolving the contradiction between secure attachment and easy removal.
Solution Approach 2:
The groove employs asymmetric wall angles where the first wall angle differs from the second wall angle. This asymmetry creates directional friction characteristics that facilitate easy insertion while maintaining secure retention, preventing accidental dislodgement without requiring excessive removal force.
2Ease of operation
If the O-ring expands laterally to facilitate easy insertion, then the ease of operation is improved, but the fit security may be compromised
Solution Approach 1:
The O-ring's lateral expansion and contraction is made dynamic rather than static. During insertion, the O-ring expands laterally to accommodate the implant; during removal, it contracts to maintain fit security. This dynamic behavior resolves the contradiction between ease of insertion and fit security.
Solution Approach 2:
The groove geometry parameters (wall angles) are specifically designed to control the O-ring's expansion and contraction behavior. The first wall angle facilitates expansion during insertion, while the second wall angle promotes contraction during removal, thereby maintaining fit security while improving ease of operation.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The asymmetric groove and O-ring design provides a secure, frictional fit that prevents accidental dislodgement and minimizes the force needed for assembly and disassembly, protecting the taper and enhancing surgical precision.
Implementation Method 1
The asymmetry of the third cavity portion allows the O-ring to expand laterally outward farther when it is biased towards the distal end (for example, when a taper is inserted into the cavity) compared to when it is biased towards the proximal end
Implementation Method 2
The asymmetry of the third cavity portion allows the O-ring to expand laterally outward farther when it is biased towards the distal end (for example, when a taper is inserted into the cavity) compared to when it is biased towards the proximal end (for example, when a taper in the cavity is moved towards the opening to remove the taper from the cavity)
Implementation Method 3
The trial head is placed on the precision taper and can be held on by friction so it does not come off accidently
Data Source
AI summary
An implant trial head includes a distal end, a proximal end including an opening in an exterior surface, and a cavity extending from the opening into the implant trial head. The cavity includes an asymmetric groove in an interior wall of the cavity, the groove aligned substantially perpendicular to a longitudinal axis of the implant trial head, and a cross-sectional diameter of the asymmetric groove. The implant trial head includes an O-ring positioned in the asymmetric groove.