Surgical Mid-Foot Compression Pin Conical Thread Design
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Solution Overview
Problem
Existing mid-foot compression pins lack effective compressive action and secure anchoring in foot bones, making them difficult to implant and remove.
Innovation Solution
A surgical mid-foot compression pin with a conical rear outer thread that tapers towards the front end, providing improved compressive action and secure anchoring, along with a cylindrical core region and thread design to prevent rotation and ensure stable positioning.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If a stepped cylindrical sleeve contour is used in the rear outer thread, then the compression pin can be manufactured with simple geometry, but the compressive action is insufficient
Solution Approach 1:
The patent applies parameter changes by transitioning from a cylindrical to a conical sleeve contour in the rear outer thread. This geometric parameter modification enables the thread to actively compress bone fragments during insertion, significantly improving compressive action while maintaining manufacturing feasibility through standard machining processes
2Strength
If a conical sleeve contour is used in the rear outer thread, then the compressive effect is improved, but the device complexity increases
Solution Approach 1:
The patent applies local quality by implementing the conical sleeve contour specifically in the rear outer thread region while keeping the front outer thread with a different geometry. This localized geometric modification concentrates the compressive function where needed without requiring the entire device to be complex, thus improving compressive effect while limiting overall device complexity
3Reliability
If the compression pin is screwed in firmly to achieve secure anchoring, then the anchoring durability is improved, but the removal process becomes difficult
Solution Approach 1:
The patent applies dynamics by designing the compression pin with a conical rear thread that creates asymmetric engagement with the bone. During insertion, the conical geometry guides the pin into firm anchoring, but during removal, the same geometry allows controlled backout when proper torque is applied, thus achieving both secure anchoring and removable design
4Strength
If the pitch of the front outer thread is greater than the rear outer thread to achieve compression, then the compressive action is improved, but the thread design complexity increases
Solution Approach 1:
The patent applies parameter changes by varying the pitch parameter between the front and rear outer threads. The front thread has a greater pitch for initial engagement, while the rear thread has a smaller pitch for compression. This parameter variation is achieved through standard thread cutting processes, improving compressive action without excessive design complexity
Data Source
AI summary
A surgical mid-foot compression pin (1), includes a core region (2) having a drive, a front thread portion (6) having a front outer thread (7), a rear thread portion (9) having a rear outer thread (10), and a middle portion (8) arranged between the thread portions, the pitch of the front outer thread (S1) being greater than that of the rear outer thread (10) so as to achieve a compression. In accordance with the invention, the rear outer thread (10) has a conical sleeve contour, which tapers in the direction of the front end (3) of the compression pin (1).