Glenoid Adapter Misaligned Axes for Reverse Shoulder Conversion
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Solution Overview
Problem
Current shoulder prostheses face challenges in converting from resurfacing to reverse prosthesis without removing the glenoid anchor, especially when it is implanted in a non-central position, leading to misalignment issues and difficulties in stabilizing the reverse prosthesis.
Innovation Solution
A glenoid adapter with a fixing projection and attachment portion of truncated-cone shape, misaligned with each other, allowing secure coupling with the glenoid anchor and convex articular component, enabling conversion without removing the anchor, even if it's not centrally positioned, using cone-shaped coupling and securing screws for stability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a standard glenoid anchor is used in a non-central position for resurfacing prosthesis, then the prosthesis can be implanted in patients with limited bone availability, but conversion to reverse prosthesis becomes difficult without removing the anchor
Solution Approach 1:
The adapter is divided into distinct functional segments: a fixing projection for anchoring to the existing glenoid anchor, a flange for stabilization, and an attachment portion for the convex articular component. This segmentation allows each part to perform its specific function independently, enabling conversion without removing the original anchor.
Solution Approach 2:
The adapter acts as an intermediary component between the existing glenoid anchor and the convex articular component of the reverse prosthesis. It mediates the connection, allowing conversion while maintaining the original anchor position, thus simplifying the conversion procedure.
2Manufacturing precision
If the glenoid anchor is implanted in a peripheral position, then bone tissue is preserved, but alignment with the glenoid cavity center becomes problematic
Solution Approach 1:
The adapter incorporates asymmetric design elements, including a misaligned attachment portion relative to the fixing projection axis. This asymmetry allows the adapter to compensate for the peripheral anchor position and achieve proper alignment of the convex articular component with the glenoid cavity center.
Solution Approach 2:
The adapter introduces dimensional adjustment by extending the attachment portion in a direction misaligned with the fixing projection axis. This dimensional change enables repositioning of the convex articular component to achieve proper alignment despite the peripheral anchor location.
3Device complexity
If the attachment portion is aligned with the fixing projection axis, then the structure is simplified, but correct positioning of the convex articular component cannot be achieved with peripheral anchors
Solution Approach 1:
The adapter deliberately employs asymmetric positioning of the attachment portion relative to the fixing projection axis. This asymmetry is designed to compensate for peripheral anchor placement, ensuring accurate positioning of the convex articular component while maintaining reasonable structural simplicity.
Data Source
AI summary
The present invention relates to an improved glenoid adapter for shoulder prostheses, in particular for the conversion of an anatomic resurfacing prosthesis to a reverse shoulder prosthesis, comprising: •—at least one fixing projection (2) having an own axis (X) and being arranged to be fixed to the glenoid cavity (301) of the scapula (300) •—a flange (4) integral with said fixing projection (2); •—an attachment portion (3) integral with the flange (4) and extended in the direction opposite said fixing projection (2), as well as arranged to be coupled with an articular component (10) of reverse prosthesis provided with a convex articular surface (11), said attachment portion (3) having an own longitudinal axis (Y); both the fixing projection (2) and the attachment portion (3) have truncated-cone shape and that the axis of the attachment portion (Y) is misaligned with respect to the fixing projection axis (X); said flange (4) has a glenoid surface (4a) from which said fixing attachment (2) rises.