Bone Fixation Screw Wing for Pull-Out Resistance
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Solution Overview
Problem
Existing bone fixation screws often fail to withstand varying loads, leading to screw pull-out and reduced bone rigidity, especially in weakened bones, due to inadequate distribution of forces.
Innovation Solution
A bone fixation device with a threaded shaft and a wing element that compresses to increase the contact area with the bone cortex, distributing forces over a larger area and enhancing holding strength.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If a conventional bone fixation screw is used, then the screw can be inserted into the bone, but the screw cannot withstand varying loads and may pull out, reducing bone rigidity
Solution Approach 1:
The wing element extends laterally from the shaft in a direction perpendicular to the longitudinal axis, adding a transverse dimension to the force distribution. This lateral extension allows forces to be distributed across a broader area of the bone cortex, preventing pull-out along the longitudinal axis while maintaining insertion capability.
Solution Approach 2:
The fixation device is divided into distinct functional segments: the threaded shaft for insertion and anchoring, the connector for structural linkage, and the wing element for force distribution. This segmentation allows each component to specialize in its function, with the wing specifically designed to distribute loads laterally across the bone cortex.
2Strength
If the contact area with the bone is increased to distribute forces, then the holding strength improves, but the device complexity increases
Solution Approach 1:
The wing element is positioned specifically at the proximal end of the shaft where force distribution is most critical for preventing pull-out. The lateral extensions are oriented to engage with the bone cortex at the optimal location, concentrating the force-distributing function where it is most needed rather than uniformly distributing complexity throughout the entire device.
3Area of stationary object
If the wing profile is increased in the locked configuration, then forces are distributed over a larger area of the cortex, but the insertion configuration must accommodate this larger profile
Solution Approach 1:
The wing element transitions dynamically between configurations: during insertion, the wing profile is oriented to minimize the opening required; once positioned, the wing is rotated or reoriented to its locked configuration where the full lateral profile engages with the bone cortex for maximum force distribution. This dynamic reconfiguration allows the device to overcome the contradiction between insertion ease and locked stability.
Data Source
AI summary
A bone fixation device includes (a) a threaded shaft extending from a proximal end to a distal end; (b) a head located at the proximal end of the shaft; (c) a connector threadably engaging the threaded shaft and movable therealong; and (d) an extension member movable between an insertion configuration for insertion through an opening in a cortex of a bone to a locked configuration when pressed against an inner surface of the cortex. The profile of the wing in the locked configuration in the plane perpendicular to the longitudinal axis of the shaft is increased relative to the insertion configuration to distribute forces transmitted between the bone fixation apparatus and the bone over an increased area of the cortex.