Acetabular Sleeve for Safer Liner Removal
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Solution Overview
Problem
Revision surgery for hip joint reconstruction is challenging due to the difficulty in removing inner acetabular liners without damaging the acetabular shell or bone, especially when conventional tools are used to chip away cement mantles, which is time-consuming and risky.
Innovation Solution
An acetabular implant system comprising a metallic inner hemispherical construct and a polymeric sleeve with protrusions that snap-fit onto the liner, providing insulation and facilitating easier removal by creating a void for tool access, reducing the risk of bone damage and simplifying the extraction process.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If conventional tools such as osteotomes or drills are used to chip away exposed cement mantle between the acetabular shell and inner liner, then the inner liner can be removed, but the process is time-consuming and may result in damage to the acetabular shell and/or bone underneath it
Solution Approach 1:
A polymeric sleeve is introduced as an intermediary component between the inner liner and the acetabular shell. The sleeve is secured to the inner liner with cement and extends into the cement mantle, providing a dedicated interface for tool engagement. This mediator allows surgeons to remove the liner without directly manipulating the fragile cement mantle or applying excessive force to the shell and bone.
Solution Approach 2:
The system segments the removal function by separating the liner from the shell through the intermediate sleeve. The sleeve can be independently engaged and manipulated, allowing the liner to be removed as a distinct unit from the shell-cement-bone assembly, thereby protecting the shell and bone from damage during the extraction process.
2Productivity
If an acetabular extraction device is used to remove the acetabular shell, cement mantle and inner liner, then complete removal is achieved, but significant forces applied to the cement mantle pose a high risk of damage to bone or even bone loss may occur
Solution Approach 1:
The polymeric sleeve serves as a mediator that absorbs and distributes extraction forces. Instead of applying significant forces directly to the cement mantle and bone, the sleeve provides a compliant interface that allows controlled removal while protecting the underlying bone structure from traumatic forces.
Solution Approach 2:
The sleeve changes the mechanical parameters of the extraction process by providing a dedicated engagement interface with specific geometric features (such as slots or grooves) that allow tool insertion and controlled leveraging. This changes the force distribution from concentrated loads on the bone to distributed loads through the sleeve material.
3Ease of manufacture
If conventional tools are used to access the cement toward the polar regions of the acetabular elements, then complete cement removal is possible, but the hemispherical geometry makes it difficult to access these regions
Solution Approach 1:
The polymeric sleeve is pre-formed with engagement features (slots, grooves, or channels) that extend toward the polar regions before implantation. This preliminary configuration provides built-in access pathways that guide extraction tools directly to the cement mantle in hard-to-reach areas, eliminating the need for complex manual access techniques during surgery.
Data Source
AI summary
In one embodiment, the present disclosure relates to an acetabular implant system with a liner and a sleeve. The liner includes a convex outer surface shaped to correspond to an interior of an acetabular cup and has an equatorial region and a polar region. The convex outer surface includes a plurality of liner engagement features thereon. The sleeve includes an inner surface with a plurality of sleeve engagement features thereon. The inner surface of the sleeve is sized to be flush with the convex outer surface of the liner. When the sleeve is engaged with the liner, the liner engagement features engage the sleeve engagement features.