Surgical Fastener Asymmetric Through-Hole for Tibia Adjustment
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Solution Overview
Problem
Existing surgical instruments for knee replacement face challenges in fine adjustment and positioning after being fastened to the tibia due to through-holes with uniform or similar-sized profiles, limiting the ability to precisely align cutting guides for accurate cuts.
Innovation Solution
A surgical instrument design featuring a fastener with a through-hole that has a larger opening at one end and a smaller opening at the other, allowing for movement and adjustment relative to the pin fastened to the tibia, enabling precise positioning and alignment of the cutting guide.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If a through-hole with uniform profile is used in the fastener, then the fastener provides stable fixation to the tibia, but the surgical instrument cannot be finely adjusted after fastening
Solution Approach 1:
The through-hole is designed with non-uniform profile, having a first opening and a second opening with different sizes. This local variation in geometry allows the fastener to provide stable fixation while enabling fine adjustment capability, as the asymmetric profile creates a specific contact area that permits controlled movement about the pin contact point.
Solution Approach 2:
The through-hole employs an asymmetric profile where the first opening and second opening have different dimensions. This asymmetry allows the fastener to rotate or move to a limited extent about the pin contact point, providing the surgeon with fine adjustment capability while maintaining secure fixation through the asymmetric contact geometry.
2Ease of operation
If a through-hole with larger opening is used, then the fastener can move for adjustment, but the fixation strength may be reduced
Solution Approach 1:
The through-hole features localized opening variations at specific positions (first opening and second opening) rather than uniformly large openings throughout. This localized geometry provides adjustment capability where needed while maintaining adequate fixation strength through the overall fastener-tibia contact area.
Solution Approach 2:
The through-hole provides just enough movement capability for fine adjustment purposes, rather than allowing excessive movement. The opening sizes are carefully designed to permit only the necessary adjustment range, thereby maintaining fixation strength while achieving positioning precision.
3Strength
If the through-hole opening is made smaller, then fixation is more secure, but the fastener cannot move for alignment adjustment
Solution Approach 1:
The through-hole incorporates localized openings of specific sizes at different locations. The first opening and second opening are designed with different dimensions to create a contact area that allows limited movement for alignment adjustment while maintaining secure fixation through the overall fastener design.
Solution Approach 2:
The asymmetric opening profile creates a specific contact geometry between the fastener and tibia that permits controlled movement for alignment adjustment. The asymmetric design ensures that the fastener can move to a limited extent for positioning while maintaining secure fixation through the asymmetric contact surface.
Data Source
AI summary
A surgical instrument includes a rod unit extending in a first direction along a tibia of a human body, an attachment located at a first end of the rod unit that is attachable to an ankle joint, and a fastener located at a second end of the rod unit that is fasten-able to a proximal end of the tibia. The fastener has a through-hole extending in a second direction that crosses the first direction, and a pin that is arranged in the through-hole and that has a tip which is received in the tibia. The through-hole has an opening larger than a profile of the pin to allow the fastener to move about a portion of contact between the through-hole and the pin when the pin is received in the tibia.