Shoulder Prosthesis Compression Screw Assembly

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Solution Overview

Problem

Current shoulder prostheses face challenges in accurately assembling the glenosphere to the glenoid component due to limited space, leading to potential implantation failures and reduced biomechanical stability, especially in cases with rotator cuff impairments.

Innovation Solution

A compact shoulder prosthesis design featuring a metaglene element with a central compression screw and a connector element that allows for adjustable compression and secure fixation, along with a glenosphere element, facilitating easier assembly and improved bone integration, suitable for both anatomical and reverse models.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Adaptability or versatility

If a traditional anatomical prosthesis is used, then anatomical biomechanics are preserved, but the prosthesis cannot be effectively applied in cases of rotator cuff impairment

Engineering Contradiction:

Improveapplicability to rotator cuff impairment casesVSAvoidanatomical biomechanics

Core Design Contradiction:

Adaptability or versatilityVSStability of the object's composition

Solution Approach 1:

The patent applies the reverse prosthesis model where the anatomical configuration is inverted: a convex glenosphere is fixed to the scapula instead of the humerus, and a concave humeral component receives it. This inversion allows the prosthesis to function effectively in rotator cuff impairment cases while maintaining biomechanical stability through the complementary curved surfaces and compression mechanism.

Inventive Principle:

Principle #13The other way round (Inversion)

2Volume of moving object

If the glenosphere is made compact to reduce invasiveness, then implantation invasiveness is reduced, but assembly precision becomes more difficult

Engineering Contradiction:

Improveglenosphere sizeVSAvoidassembly precision

Core Design Contradiction:

Volume of moving objectVSManufacturing precision

Solution Approach 1:

The connector element serves as an intermediary component between the metaglene and glenosphere. It provides a standardized interface with threaded holes and compression screw engagement features, enabling precise assembly of the compact components while maintaining ease of implantation. The connector mediates the connection, ensuring accuracy despite the reduced size of individual components.

Inventive Principle:

Principle #24Intermediary (Mediator)

3Volume of stationary object

If the available space in the glenoid cavity is reduced, then the prosthesis becomes less invasive, but the accuracy of glenosphere positioning is compromised

Engineering Contradiction:

Improveglenoid cavity spaceVSAvoidglenosphere positioning accuracy

Core Design Contradiction:

Volume of stationary objectVSMeasurement precision

Solution Approach 1:

The prosthesis components are nested within the limited glenoid cavity space: the metaglene base plate sits in the glenoid, the connector element attaches to it, and the glenosphere nests within the connector's housing. This nested arrangement maximizes the use of available space while maintaining proper positioning through the guided interface between components.

Inventive Principle:

Principle #7Nested doll (Nesting)

4Reliability

If a compression mechanism is added to improve fixation, then bone integration is enhanced, but the device complexity increases

Engineering Contradiction:

Improvefixation strengthVSAvoidprosthesis structure

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The compression function is merged into the connector element design. The compression screw integrates with the connector's threaded hole and engages directly with the metaglene, combining the fastening and compression functions in a single integrated mechanism rather than separate components. This reduces overall device complexity while maintaining reliable fixation.

Inventive Principle:

Principle #5Merging (Combining)

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 enables precise and stable assembly of the prosthesis, enhancing bone growth and reducing invasiveness during implantation and rehabilitation, while accommodating anatomical variations for optimal biomechanical performance.

Implementation Method 1

a central compression screw housed in said through-hole in the centre of said metaglene element

Methodology Applied

Scientific EffectCompression: Compression

Data Source

PatentUS12121451B2Shoulder prosthesis

Publication Date: 2024.10.22 LIMACORPORATE SPA

AI summary

The present invention relates to a shoulder prosthesis comprising:—a metaglene element (2) or baseplate;—a pin (3) projecting from said metaglene element (2);—a through-hole (11) in the centre of said metaglene element (2);—at least one through-hole (5) formed in a periphery of the metaglene element (2) with respect to said central through-hole (11);—a glenosphere element (12) opposite said pin (3) with respect to said metaglene element (2);—a central compression screw (9) housed in said through-hole (11) in the centre of said metaglene element (2) and having a head abutting onto the bottom of said hole (11); and—wherein the central through-hole (11) has an opening (11A) that is threaded in a stretch to receive the end of a safety screw (18) passing through the glenosphere element (12);—a connector element (13) between the metaglene element (2) and the glenosphere element (12), the metaglene element (2) providing a seat (14) for housing the connector element (13) projecting around the central through-hole (11).