Non-impinging Dual Mobility Hip Prosthesis with Recessed Liner Rim
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Solution Overview
Problem
Hip prostheses face a trade-off between mitigating dislocation and acetabular cup liner damage, with deeper acetabular components reducing dislocation risk but increasing liner damage, and existing solutions like bumper formations or higher head-to-neck ratios not fully addressing impingement issues.
Innovation Solution
A dual mobility hip prosthesis design with a recessed liner rim and angled acetabular cup rim to tolerate impingement without bumper formations, allowing for a deeper construction that reduces dislocation risk while minimizing liner damage through a non-rotatably captured liner with frustoconical locking tapers.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the acetabular componentry is made deeper, then the likelihood of dislocation is decreased, but the likelihood of liner damage increases due to lateral forces impinging the liner between the neck and inner surfaces of the acetabular cup
Solution Approach 1:
The acetabular componentry is segmented into two distinct functional surfaces: a deep acetabular cup surface for providing dislocation prevention, and a separate impingement surface positioned to receive lateral forces from the neck. This segmentation allows the deep cup to prevent dislocation while the dedicated impingement surface protects the liner from damage by directing lateral forces away from it.
Solution Approach 2:
An impingement surface is introduced as an intermediary element between the neck and the liner. This surface acts as a mediator that receives lateral impinging forces from the neck, preventing these forces from being transmitted to the liner. The impingement surface thus protects the liner from damage while allowing the acetabular componentry to maintain its deep configuration for dislocation prevention.
2Object-affected harmful factors
If the acetabular componentry is made shallower to eliminate lateral forces impinging the liner, then liner damage is mitigated, but the likelihood of dislocation increases
Solution Approach 1:
The acetabular componentry is divided into functional segments: a deep acetabular cup portion that provides dislocation prevention, and a separately positioned impingement surface that handles lateral forces. This segmentation enables the cup to be deep for stability while the impingement surface protects the liner, resolving the contradiction between depth and liner protection.
Solution Approach 2:
The impingement surface serves as an intermediary structure that intercepts lateral forces from the neck before they can reach the liner. This mediator allows the acetabular componentry to maintain a deep configuration for dislocation prevention while the impingement surface absorbs the harmful lateral forces, protecting the liner from damage.
3Object-affected harmful factors
If dual mobility bearing component is used to improve effective head-to-neck diameter ratio and avoid prosthetic impingement, then impingement is reduced, but insertion depth becomes especially important to reduce dislocation likelihood
Solution Approach 1:
The impingement surface acts as an intermediary that manages lateral forces, working in conjunction with the dual mobility bearing component. This combination allows the prosthesis to tolerate greater ranges of motion while the impingement surface protects the liner, reducing the criticality of precise insertion depth control for preventing both impingement and dislocation.
Solution Approach 2:
The system segments the force management functions: the dual mobility bearing component handles the head-to-neck diameter ratio and range of motion, while the impingement surface separately manages lateral force protection. This segmentation reduces the sensitivity to insertion depth precision by distributing the protective functions across multiple specialized elements.
Data Source
AI summary
Dual mobility hip prosthesis has a liner rim that recessed with respect to an acetabular cup rim thereof so that an adjacent contact surface of the neck impinges the acetabular cup rim at extreme positions without impinging the liner rim. Furthermore, the acetabular cup rim defines an inner contact face correspondingly angled to the adjacent contact surface of the neck at the extreme positions to reduce point contact loading between the acetabular cup rim and the adjacent contact surface of the neck. As such the present prosthesis tolerates prosthetic impingement between the rim of the acetabular cup and the neck of the femoral component by mitigating against point contact loading force whilst eliminating impingement of edges of the polymeric liner between an edge of the neck and the rim of the acetabular cup and also allowing for sufficiently deep acetabular componentry with reduced likelihood of dislocation.