Interlocking Bone Screw and Washer for Spinal Stabilization
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Solution Overview
Problem
Conventional methods for immobilizing spinal facet joints, such as transfacet bolts, are not suitable for all spinal morphologies and can be cumbersome, lacking alternative devices or assemblies for effective immobilization.
Innovation Solution
A cannulated bone screw system comprising a screw with a threaded and non-threaded portion, and a washer with interlocking teeth and spikes, designed to accommodate different bone morphologies by mating to prevent screw backout while allowing pivoting, along with a screw holder and drill guide for secure insertion.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a transfacet bolt is used to immobilize a facet joint, then the joint is stabilized, but the method is not suitable for all spinal morphologies and is cumbersome
Solution Approach 1:
The washer is designed with a toothed interior surface that engages with teeth on the screw, creating a dynamic interlocking mechanism. This allows the assembly to pivot and conform to different bone morphologies while maintaining stabilization, resolving the contradiction between reliable fixation and adaptability to various spinal anatomies
Solution Approach 2:
The device is divided into distinct functional components: a threaded portion for bone engagement, a non-threaded portion with teeth for interlocking with the washer, and a washer with spikes for additional stabilization. This segmentation allows each component to perform its specific function optimally while collectively providing versatile adaptation to different spinal morphologies
2Reliability
If the screw is prevented from backing out by interlocking teeth, then stability is improved, but the device complexity increases
Solution Approach 1:
The stabilization function is merged into the washer component through the interlocking tooth mechanism. The washer combines multiple functions: it prevents screw backout through tooth engagement, provides additional bone stabilization through spikes, and allows pivoting motion. This merging reduces overall device complexity by consolidating multiple stabilization mechanisms into a single integrated component
Data Source
AI summary
The present disclosure provides a cannulated bone screw system including a screw with a threaded portion, a non-threaded portion, and a first plurality of teeth spaced apart from a screw head; and a washer with an interior portion with a second plurality of teeth and an opening and an outer portion with a plurality of spikes. The first plurality of teeth are on an inferior convex surface; wherein the second plurality of teeth are on a superior concave surface; and wherein the first plurality of teeth and the second plurality of teeth are operable to mate to prevent the screw from backing out of the washer while allowing the cannulated bone screw system to conform/pivot in order to accommodate different bone morphologies.