Stemless Shoulder Prosthesis Anchoring via Central Bone Space
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Solution Overview
Problem
Conventional shoulder prostheses with stems require preparation of the humeral canal, leading to bone loss and increased surgical time and cost, whereas stemless designs lack effective anchoring methods that preserve bone and simplify surgery.
Innovation Solution
A stemless shoulder prosthesis with a base portion and anchoring means featuring protrusions that extend between inner and outer ends, creating a central space for bone integration, and optional additional anchoring elements like webs and openings to enhance stability and osseointegration.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a stemmed shoulder prosthesis is used, then stable fixation is achieved, but bone loss occurs due to humeral canal preparation
Solution Approach 1:
The invention extracts the stem component from the prosthesis design, eliminating the need for humeral canal preparation while retaining fixation functionality through protrusions that anchor directly to the humeral head metaphysis
Solution Approach 2:
The anchoring means are segmented into multiple protrusions distributed around the base portion, each contributing to fixation stability without requiring a continuous stem structure, thereby preserving bone stock
2Reliability
If a stemmed shoulder prosthesis is used, then fixation stability is achieved, but surgical time and cost increase
Solution Approach 1:
By removing the stem and eliminating canal preparation steps, the surgical procedure is simplified and time is reduced while maintaining reliable fixation through the protrusion-based anchoring system
3Loss of substance
If a stemless shoulder prosthesis is used, then bone is conserved, but anchoring effectiveness is reduced
Solution Approach 1:
The protrusions are strategically designed with specific geometries, lengths, and distributions to concentrate anchoring force in the metaphyseal region where bone quality is optimal, maximizing fixation effectiveness without requiring stem insertion into the diaphysis
Solution Approach 2:
The anchoring function is transitioned from a longitudinal stem-based system to a radial protrusion-based system, distributing fixation forces in multiple dimensions around the humeral head to achieve stable anchoring without stem insertion
4Strength
If protrusions are designed to extend far from the base portion, then anchoring strength increases, but device complexity increases
Solution Approach 1:
The protrusions are integrated as part of a unitary base portion structure, combining simplicity of manufacture with optimized geometry for anchoring strength, avoiding complex assembly while maintaining mechanical performance
Data Source
AI summary
The present disclosure relates to a stemless shoulder prosthesis comprising a fixation device for fixing the prosthesis to a resected humerus bone, the fixation device comprising a base portion (11, 31, 32) and anchoring means (12, 12′), the base portion (11, 31, 32) having a distal side adapted to contact a resection plane of the bone and a proximal side for carrying a humeral head. The anchoring means (12, 12′) are connected to the distal side of the base portion (11, 31, 32) and adapted to fix the prosthesis to the bone. The anchoring means (12, 12′) define a central axis (C), wherein the anchoring means (12, 12′) comprise a plurality of protrusions (13, 13′, 13a, 13b, 13c) projecting from the base portion (11, 31, 32), each protrusion (13, 13′, 13a, 13b, 13c) extending between an inner end (I) and an outer end (O). The protrusions (13, 13′, 13a, 13b, 13c) define a free central space (F) around the central axis (C).