Acetabular Endoprosthesis Protective Element Design

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Solution Overview

Problem

Hip joint endoprosthesis systems experience damage due to impingement between the joint head shell and the femoral shaft, particularly in cases where the femoral neck has roughness or edges, leading to potential harm to the joint head shell.

Innovation Solution

Incorporating a protective element on the ball head that limits its movement towards the femoral shaft, designed as a protective sleeve or cone connection, to prevent direct contact with the femoral shaft or neck, thereby minimizing damage to the joint head shell.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of operation

If the joint head shell is allowed to move freely relative to the femoral shaft, then the mobility of the hip joint endoprosthesis system is improved, but the risk of damage to the joint head shell due to impingement increases

Engineering Contradiction:
ImprovemobilityVSAvoidrisk of damage
Core Design Contradiction:
Ease of operationVSReliability

Solution Approach 1:

The protective element acts as an intermediary component between the joint head shell and the femoral shaft. It is integrated into the ball head structure and extends to contact the femoral shaft or prosthetic neck before the joint head shell can reach it, thereby mediating the interaction and preventing direct harmful contact while preserving the dual mobility function

Inventive Principle:
Principle #24Intermediary (Mediator)

2Reliability

If a protective element is added to prevent impingement, then the protection of the joint head shell is improved, but the device complexity increases

Engineering Contradiction:
Improveprotection of joint head shellVSAvoidstructure complexity
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

The protective element is merged with the ball head structure, forming an integrated component rather than a separate attachment. The ball head serves dual functions: maintaining the dual mobility mechanism and providing the protective element that prevents impingement, thereby combining protective function with existing structural elements

Inventive Principle:
Principle #5Merging (Combining)

Solution Approach 2:

The protective element is designed as a distinct segment or feature of the ball head, allowing it to perform its protective function independently while being structurally integrated. This segmentation enables the protective function to be added without fundamentally redesigning the entire joint head assembly

Inventive Principle:
Principle #1Segmentation

Data Source

PatentEP3721837B1Acetabular endoprosthesis system
Publication Date: 2024.10.23 AESCULAP AG
  • EP3721837B1 patent drawingFigure 1
  • EP3721837B1 patent drawingFigure 2
  • EP3721837B1 patent drawingFigure 3

AI summary

To improve a hip joint endoprosthesis system comprising a socket and a joint head corresponding to the socket for forming a ball-and-socket joint, which joint head can be coupled to a femoral stem, wherein the socket has a socket shell with an insert recess into which a socket insert with a hollow spherical socket surface is inserted, wherein the joint head is designed in two parts and comprises at least one ball head that can be coupled to the femoral stem and a joint head shell, and wherein the joint head shell is ball-jointed on one side to the at least one ball head and on the other side to the socket insert, in such a way as to minimize the risk of damage, in particular to the joint head shell, it is proposed that the at least one ball head includes a protective element to limit movement of the joint head shell towards the femoral stem.