Vault-Filling Shoulder Prosthesis Bone Preservation
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Solution Overview
Problem
Conventional shoulder prostheses face challenges in securing and anchoring due to deterioration of subchondral and cancellous bone in the glenoid vault, often requiring removal of healthy bone stock, which is undesirable.
Innovation Solution
A shoulder prosthesis design featuring a vault-filling component with a metallic or polymeric structure, including a vault-filling first portion and a projecting second portion that define a bone space, along with bone attachment members like screws or cement, to provide enhanced support and anchoring without necessitating extensive bone removal.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a conventional glenoid prosthesis is used, then the prosthesis can be implanted with standard design, but the prosthesis may loosen and fail due to inadequate support and anchoring from deteriorated subchondral bone and cancellous bone
Solution Approach 1:
The glenoid prosthesis is divided into multiple components: a vault-filling component that occupies the glenoid vault cavity, a bearing component for articulation, and multiple bone attachment members (pegs or keels) that extend into the cancellous bone. This segmentation allows each component to perform its specific function - the vault-filling component provides structural support, the bearing component enables movement, and the bone attachment members provide anchoring - thereby achieving reliable fixation even when bone quality is poor
Solution Approach 2:
The bone attachment members (pegs or keels) are nested within the glenoid vault cavity, extending from the vault-filling component into the cancellous bone. This nested configuration allows the prosthesis to utilize the available bone stock deep within the vault for anchoring, bypassing the deteriorated subchondral bone at the surface and achieving stable fixation
2Reliability
If a stem portion is used to substantially fill the glenoid vault, then anchoring is improved for complete bone erosion, but healthy subchondral and cancellous bone stock is removed in patients with partial erosion
Solution Approach 1:
The vault-filling component is designed with varying densities or material properties in different regions - the portion contacting deteriorated bone may be more compliant or porous to accommodate poor bone quality, while regions adjacent to healthy bone preserve its integrity. This local differentiation allows the prosthesis to adapt to varying bone quality within the same patient, providing reliable anchoring without unnecessarily removing healthy bone stock
Solution Approach 2:
Instead of completely filling the glenoid vault with a stem portion (excessive action), the prosthesis uses a vault-filling component that partially occupies the cavity, strategically positioned to reach the viable cancellous bone while leaving healthy subchondral bone intact. This partial action approach provides sufficient anchoring for patients with partial erosion without the bone removal required by complete vault filling
Data Source
AI summary
A shoulder prosthesis includes a vault-filling component defining a bearing-facing surface and having a first coupling component, the vault-filling component including (i) a vault-filling first portion defining a first part of the bearing-facing surface, and (ii) a projecting second portion projecting from the vault-filling first portion so as to define a second part of the bearing-facing surface. The vault-filling first portion and the projecting second portion define a bone space therebetween. The shoulder prosthesis further includes a bearing component defining a bearing surface and having a second coupling component configured to cooperate with the first coupling component to couple the bearing component to the vault-filling component. At least one bone attachment member positioned in the bone space. The projecting second portion of the vault-filling component further defines a scapula-facing surface.