Bone Screw with Channels for Bone Growth and Fracture Prevention
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Solution Overview
Problem
Cannulated bone screws are prone to fracture and 'backing out' of the bone due to counter rotation and inadequate bone purchase, leading to screw failure during insertion and instability in bone fixation.
Innovation Solution
A bone screw design featuring contiguous threads, non-threaded portions with channels for bone particulate deposition, and a tapered shaft to enhance bone purchase and reduce counter rotation, along with sharp edges for cutting bone, which increases the screw's robustness and integrity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If cannulated bone screws are used with standard design, then they can be inserted into bone, but they are prone to fracture and backing out due to counter rotation and inadequate bone purchase
Solution Approach 1:
The screw is divided into distinct functional segments: a threaded portion for bone engagement and a non-threaded cannulated portion for guide wire passage. This segmentation allows each portion to be optimized independently - the threaded portion for secure bone purchase and the cannulated portion for minimally invasive insertion, thereby improving reliability without excessive complexity
Solution Approach 2:
Different portions of the screw have different structural properties tailored to their specific functions. The threaded portion has higher density and engagement features for bone purchase, while the cannulated portion has a hollow structure for guide wire passage. This local differentiation optimizes performance in each region while maintaining overall screw integrity
Solution Approach 3:
The screw combines multiple material properties within a single component - a cannulated hollow structure for insertion guidance combined with threaded engagement features for bone fixation. This composite design integrates multiple functions (guidance, insertion, fixation) into one element, improving reliability without requiring separate components
2Ease of operation
If the screw has a cannulated structure for guide wire passage, then minimally invasive insertion is enabled, but the screw structure becomes weaker and more prone to fracture
Solution Approach 1:
The cannulated screw is segmented into a non-threaded cannulated portion for guide wire passage and a threaded portion for structural strength. By concentrating the threading (and thus the structural reinforcement) in specific portions rather than the entire length, the design maintains ease of minimally invasive insertion through the cannulated section while ensuring sufficient strength in the threaded engagement section
Solution Approach 2:
The screw structure has varying wall thickness and structural properties along its length - the cannulated portion allows guide wire passage while the threaded portion has enhanced structural characteristics. This local quality differentiation enables the screw to be easy to insert through the cannulated section while maintaining adequate strength where the threads provide bone engagement
3Adaptability or versatility
If the screw threads are discontinuous to allow channel formation, then bone particulate can be deposited, but the bone purchase is reduced
Solution Approach 1:
The screw is segmented into threaded and non-threaded portions, with the non-threaded portion containing channels for bone particulate deposition. This segmentation allows the threaded portions to maintain continuous engagement for bone purchase while the non-threaded cannulated portions provide adaptability for bone growth promotion through particulate deposition
Solution Approach 2:
Different portions of the screw have different functional qualities - the threaded portions provide continuous bone engagement and purchase, while the non-threaded cannulated portions with channels provide localized adaptability for bone growth. This local quality differentiation allows the screw to simultaneously maintain reliable bone purchase and promote bone growth without compromising either function
Data Source
AI summary
Embodiments of the invention may prevent or diminish a bone screw from “backing out” from bone. Bone particulate residing in channels of the bone screw may promote bone growth that would reduce the potential of backing out. Furthermore, bone particulate from drilling and tapping functions can cause increased friction. However, by placing bone particulate in channels of the bone screw, potential binding may be reduced resulting in less stress on the screw shaft. Also, breaking of screws during screw insertion may be reduced due to tapering of the screw.