Acetabular Liner Locking With Elastic Flange and Anti-Rotation Keys
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Solution Overview
Problem
Existing orthopaedic surgical implants face challenges in securely locking acetabular liners to acetabular cups, particularly in maintaining rotational alignment and preventing pull-out and spin-out, which can lead to implant instability and failure.
Innovation Solution
The design incorporates an acetabular bearing with a flange that deforms elastically to fit into an annular groove of the acetabular shell, utilizing anti-rotation keys and tapered surfaces for rotational alignment and a friction lock, along with a flange and relief surfaces for enhanced stability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the acetabular liner is locked to the acetabular cup using conventional methods, then the implant can be assembled, but rotational alignment is not maintained and pull-out and spin-out resistance are insufficient
Solution Approach 1:
The patent employs a spherical locking surface on the acetabular liner that mates with a corresponding spherical recess in the acetabular cup. This curved spherical interface provides automatic self-alignment and maintains rotational stability through geometric constraint, eliminating the need for complex mechanical locking mechanisms while ensuring reliable rotational alignment stability.
2Device complexity
If a simple locking mechanism is used, then device complexity is reduced, but pull-out and spin-out resistance are insufficient
Solution Approach 1:
The acetabular liner includes pre-formed engagement protrusions and corresponding recesses that are manufactured into the liner structure before implantation. These pre-configured geometric features automatically engage with the acetabular cup upon insertion, providing immediate pull-out and spin-out resistance without requiring additional locking components or complex assembly steps.
3Strength
If the flange is made rigid for structural strength, then strength is improved, but plastic deformation increases during installation
Solution Approach 1:
The flange is designed with non-uniform thickness distribution, featuring varying wall thicknesses in different regions. Thinner sections are positioned where deformation is expected during installation to facilitate easier engagement, while thicker sections maintain structural strength and rigidity where needed. This localized variation in quality allows the flange to balance both strength requirements and deformation control during the locking process.
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 solution provides secure rotational alignment and improved pull-out and spin-out resistance, ensuring long-term stability and durability of the implant by minimizing plastic deformation and enhancing mechanical retention.
Implementation Method 1
The design incorporates an acetabular bearing with a flange that deforms elastically to fit into an annular groove of the acetabular shell
Implementation Method 2
utilizing anti-rotation keys and tapered surfaces for rotational alignment and a friction lock
Data Source
AI summary
An orthopaedic implant includes an acetabular bearing and an acetabular shell component. The bearing includes a convex outer surface having a hemispherical surface, a curved lead-in surface, a flat flange surface, a curved relief surface, and a flat tapered surface. The curved relief surface extends inward relative to the flat tapered surface, and the flat flange surface extends outward relative to the flat tapered surface. The shell component includes a concave inner surface having a tapered surface configured to engage the tapered surface of the bearing. An annular groove is defined in the concave inner wall of the shell component and is configured to receive the flat flange surface. Methods for assembling and using the prosthetic implant are also disclosed.