Modular Shoulder Prosthesis Cup with Asymmetric Anchoring
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Solution Overview
Problem
Current shoulder prosthesis systems are complex, require specialized techniques, and often compromise bone integrity, leading to prolonged surgeries, potential dislocation of cement fixation, and insufficient anchoring, causing patient discomfort and increased costs.
Innovation Solution
A modular shoulder prosthesis cup with a hollow spherical shell and tubular anchoring means, allowing coupling with anchoring screws or keels, and an intermediate crown member for adaptable fixation techniques, preventing rotation and enhancing bone integration.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a humeral stem is used for fixation, then the prosthesis is securely anchored, but the bone capital is reduced and the surgical procedure becomes long and complex
Solution Approach 1:
The prosthesis is divided into separate components: a cup component for articulation and a stem component for anchoring. This segmentation allows the cup to be implanted first with simpler procedures, and the stem to be added separately, reducing overall surgical complexity while maintaining secure fixation through the stem-bone interface
Solution Approach 2:
The cup component is implanted first into the glenoid cavity before the stem is inserted into the humeral shaft. This preliminary action simplifies the surgical procedure by breaking it into manageable stages, allowing each component to be positioned and secured independently rather than requiring complex simultaneous implantation
2Reliability
If cement is used to fill the space between bone and humeral stem, then fixation is achieved, but the cement may dislocate over time causing loss of fixation
Solution Approach 1:
The cement layer is extracted from the critical load-bearing interface between the stem and bone. Instead of relying on cement for primary fixation, the design uses direct mechanical interlocking through the stem's geometric features that engage with the prepared bone cavity, eliminating the risk of cement dislocation while maintaining durable fixation
Solution Approach 2:
The chemical-bonding mechanism of cement fixation is replaced with a mechanical interlocking system. The stem features geometric profiles that physically engage with the bone cavity through friction and mechanical resistance, providing more reliable and durable fixation that does not depend on cement integrity over time
3Ease of operation
If a simple cylindrical anchor keel is used, then the cup can be fitted easily, but the cup can rotate after implantation and anchoring may be insufficient
Solution Approach 1:
The anchor keel is designed with an asymmetric geometry featuring a tapered profile rather than a simple cylindrical shape. This asymmetric form provides directional insertion that guides the cup into proper orientation while the varying diameter creates mechanical interference that prevents rotation after implantation, thereby maintaining both ease of insertion and anchoring security
Solution Approach 2:
The anchor keel incorporates curved and tapered surfaces rather than straight cylindrical geometry. The curved profile allows smooth insertion into the bone cavity while the conical shape creates a wedging effect that locks the cup in place and prevents rotational movement, combining ease of implantation with reliable anchoring
4Manufacturing precision
If multiple specialized ancillaries are used for different surgical techniques, then each technique can be performed with precision, but the costs increase and the surgical procedure becomes more complex
Solution Approach 1:
The cup component is designed with universal features that allow it to be used with multiple different stem types and fixation methods. The cup includes standardized interfaces and geometric features that are compatible with various ancillary devices, enabling a single cup design to serve multiple surgical techniques and reducing the need for technique-specific specialized equipment
Data Source
Figure 1~2
Figure 3~4
AI summary
The present invention relates to a prosthesis cup (1), particularly a shoulder prosthesis cup, comprising a shell (2) shaped substantially as a hollow spherical cap delimiting a concave inner surface (3), the shell (2) having a coupling stem (4) that extends from this inner surface (3) and is designed to permit coupling of the cup (1) to a fixing element, particularly an anchoring screw (26) or an anchoring pin (13), the cup (1) being characterized in that it additionally comprises anchoring and/or coupling means with a wall (6) which extends from the inner surface (3) of the shell (2) and has a substantially tubular shape and which, together with the coupling stem (4), delimits a recess (8) having what is substantially a ring shape.