Scaphoid Prosthesis Curved Passage Fixation
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Solution Overview
Problem
Conventional scaphoid prostheses lack biomechanical compatibility and stability, often leading to luxation and failure to prevent carpal collapse, resulting in arthrosis and arthritis, as they do not effectively interact with the patient's anatomical structure or provide sufficient fixation.
Innovation Solution
A patient-specific scaphoid prosthesis with a tubular base element and a single curved passage for fixation, designed using patient data to match the scaphoid's shape, incorporating a tendon strip for suspension through the scapholunate ligament reconstruction to ensure anatomical alignment and stability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If conventional prostheses are used as spacers without biomechanical attachment, then the prosthesis can be easily implanted, but they tend to luxate and cannot prevent carpal collapse
Solution Approach 1:
The prosthesis is divided into distinct functional segments: a tubular base element for structural support, a fixation means with curved passage for secure attachment, and a tendon strip for soft tissue reconstruction. This segmentation allows each component to be optimized for its specific function while maintaining ease of implantation through modular assembly.
Solution Approach 2:
The fixation means is nested within the tubular base element, with the curved passage integrated into the base structure. The tendon strip is then nested through this passage, creating a hierarchical structure where each element contains or supports the next, ensuring stable fixation while maintaining a compact implant design.
2Reliability
If channels are drilled in prostheses for bone growth fixation, then the prosthesis can be fixed to bone, but the tendon cannot move/glide anymore and flexibility is lost
Solution Approach 1:
The fixation is applied locally at specific sites (the curved passage in the base element and anchoring points in the lunate) rather than through extensive channel drilling. This localized fixation strategy provides stable bone attachment while preserving tendon mobility in the critical gliding regions, resolving the contradiction between fixation strength and tendon flexibility.
3Reliability
If a single curved passage is provided in the tubular base element for fixation means, then the prosthesis achieves stable fixation and prevents luxation, but the design complexity increases
Solution Approach 1:
The fixation passage is designed as a single curved (arc-shaped) channel rather than multiple straight channels. This curvature allows the passage to follow the natural anatomical path, providing stable fixation through a single continuous structure that integrates smoothly with the tubular base element, thereby achieving reliable fixation without significantly increasing design complexity.
Data Source
Figure 1~2
Figure 3a~4c
Figure 5a~5f
AI summary
A scaphoid prosthesis (100) comprises a body (102) bounded by an outer surface (101), whereby the outer surface (101) is substantially corresponding to a patient's scaphoid (1). The body (102) of the scaphoid prosthesis comprises a tubular base element (105) including a first end portion (104) and a second end portion (106) and a plurality of protruding portions (107, 108, 109). A passage (110) is provided in the tubular base element (105) for a fixation means for fixing the scaphoid prosthesis (100) in its position. The passage (110) is configured as a curved passage.