Offset Shoulder Prosthesis Base Plate Anchoring

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Solution Overview

Problem

Inverse shoulder prostheses face issues with inferior notching, where the joint socket collides with screws or bone material, leading to wear and potential anchoring failure, and difficulties in precise rotational alignment during implantation.

Innovation Solution

A shoulder prosthesis design featuring a base plate anchored to the scapula using two peg-like projections, allowing for offset positioning and secure anchoring, with a dome-shaped bottom surface and central receptacle for the joint head, enabling correct rotational alignment and minimizing the risk of damage to anchoring elements.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Adaptability or versatility

If the joint socket is positioned to avoid inferior notching, then the range of motion is improved, but the joint socket edge may collide with anchoring screws

Engineering Contradiction:

Improverange of motionVSAvoidanchoring security

Core Design Contradiction:

Adaptability or versatilityVSReliability

Solution Approach 1:

The base plate is designed with an offset arrangement relative to the glenoid cavity, positioning the joint head in a different spatial dimension. This offset placement allows the joint socket to clear the glenoid cavity edge during arm adduction while maintaining secure anchoring of the base plate to the scapula, thus resolving the conflict between range of motion and anchoring security.

Inventive Principle:

Principle #17Another dimension (Dimensionality change)

2Reliability

If additional screws are used to anchor the base plate, then the anchoring security is improved, but the risk of screw damage from inferior notching increases

Engineering Contradiction:

Improveanchoring securityVSAvoidscrew damage risk

Core Design Contradiction:

ReliabilityVSObject-affected harmful factors

Solution Approach 1:

The harmful effect of inferior notching is eliminated by extracting the anchoring screws from the danger zone near the glenoid cavity edge. The base plate is designed with anchoring elements positioned away from the inferior notching area, so that even during extreme arm adduction, the joint socket cannot collide with the anchored elements, thus securing them against damage while maintaining anchoring security.

Inventive Principle:

Principle #2Taking out (Extraction)

3Adaptability or versatility

If the joint head is offset to prevent inferior notching, then the range of motion is improved, but precise rotational alignment becomes difficult to achieve

Engineering Contradiction:

Improverange of motionVSAvoidrotational alignment accuracy

Core Design Contradiction:

Adaptability or versatilityVSManufacturing precision

Solution Approach 1:

The base plate is designed with predefined orientation features and asymmetric geometry that guide correct rotational alignment during implantation. These preliminary design elements enable the surgeon to achieve precise rotational positioning of the joint head relative to the glenoid cavity, ensuring optimal biomechanical function while maintaining the offset configuration that prevents inferior notching.

Inventive Principle:

Principle #10Preliminary action

Data Source

PatentEP2023863B1Shoulder prosthesis

Publication Date: 2016.03.16 MATHYS AG BETTLACH

Figure 1~2
Figure 3~4
Figure 5~6

AI summary

Disclosed is a shoulder prosthesis (2) comprising a socket (4) and a condyle (6) that cooperates with the socket (4). The condyle (6) also cooperates with a base plate (8) facing the scapula similar to a clamping connection (44). The condyle (6) is plugged onto the base plate (8) by means of a receptacle (42) that is embodied on the condyle (6). The base plate (8) can be anchored to the glenoid fossa (102) of the scapula (8) with the aid of two peg-type protrusions (18).