Reversible Epiphyseal Part for Modular Shoulder Prosthesis
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Solution Overview
Problem
The existing shoulder prostheses with modular epiphyseal parts require a large number of different components to accommodate various anatomical and reversed configurations, leading to increased manufacturing costs and complexity, as well as greater bone cuts and stress on fixation inserts in reversed prostheses.
Innovation Solution
A shoulder prosthesis design featuring a reversible epiphyseal part that can be rotated 180° to modify the inclination of its upper face from 135° to 145°, using a common diaphyseal part and epiphyseal parts that can be adjusted by +/- 2α, reducing the total number of necessary parts to 8 from 16.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If modular epiphyseal parts with different inclinations are used to accommodate anatomical and reversed prosthesis configurations, then the adaptability of the prosthesis system is improved, but the number of parts and device complexity increases
Solution Approach 1:
The epiphyseal part is designed with a universal structure that can serve multiple functions by rotating 180 degrees. The same epiphyseal part can be configured for both anatomical prosthesis (135° inclination) and reversed prosthesis (145° inclination) by changing its orientation, eliminating the need for separate parts for each configuration.
Solution Approach 2:
The epiphyseal part incorporates a dynamic reconfiguration capability through 180-degree rotation around an axis normal to its lower central support face. This dynamic adjustment allows the inclination angle to change from 135° to 145°, enabling the same physical part to adapt to different surgical requirements.
2Adaptability or versatility
If multiple epiphyseal parts with different inclinations are designed to cover all configurations, then the adaptability is improved, but the manufacturing cost and inventory cost increase
Solution Approach 1:
By designing a universal epiphyseal part that can be rotated to achieve different inclinations, the manufacturing cost is reduced because only one type of epiphyseal part needs to be produced rather than multiple variants. This also reduces inventory costs as fewer different parts need to be stocked.
3Adaptability or versatility
If wedge-shaped inserts are used to compensate for inclination differences in reversed prostheses, then the adaptability is improved, but the stress on the insert and fixation increases
Solution Approach 1:
Instead of using static wedge-shaped inserts that create concentrated stress, the invention uses a dynamic rotation mechanism of the entire epiphyseal part. This distributes the stress more evenly across the insert and fixation points, reducing the peak stress and improving the mechanical strength of the assembly.
Data Source
Figure 1~2
Figure 3~4
AI summary
The invention relates to a shoulder prosthesis (1) comprising a diaphyseal part (2) which extends along a diaphyseal axis (4) and on which an epiphyseal part (3) is mounted, the epiphyseal part (3) having an upper face (5) which is inclined along a frontal plane with respect to the diaphyseal axis (4), and a lower central face (6) bearing against a complementary upper face (7) of the diaphyseal part (2). According to the invention, the epiphyseal part (3) can be reversibly rotated 180° about an axis normal to the lower central face (6) bearng against the epiphyseal part (3) to modify the inclination of the upper face (5) of the epiphyseal part (3).