Variable Thread Bone Screw for Spinal Fixation
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Solution Overview
Problem
Existing spinal implant systems face challenges in achieving optimal fixation and bone growth due to limitations in traditional manufacturing techniques, which can result in inadequate stability and integration with bone tissue.
Innovation Solution
The development of a spinal implant system featuring a bone screw with a variable structured thread form, combining traditional manufacturing methods with additive manufacturing techniques, to enhance fixation and facilitate bone growth. The bone screw includes sections with solid, porous, and trabecular configurations to protect sensitive tissue and promote integration with bone.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If traditional manufacturing techniques are used to make bone screws, then the manufacturing process is simple and cost-effective, but the fixation stability and bone integration are insufficient
Solution Approach 1:
The bone screw features a thread form with non-uniform cross-sectional area along its length, creating regions of different structural properties. The major portion has a first cross-sectional area while the minor portion has a second cross-sectional area that is less than the first, allowing different sections to serve different functions - the major portion provides structural strength and fixation stability, while the minor portion facilitates bone integration and growth.
Solution Approach 2:
The thread form is divided into distinct portions along its length - a major portion and a minor portion - each with different cross-sectional areas and structural characteristics. This segmentation allows the screw to simultaneously achieve strong fixation in the major portion while promoting bone integration in the minor portion, resolving the contradiction between fixation stability and bone integration.
2Reliability
If uniform thread structure is used, then the manufacturing process is simple, but bone integration and tissue protection cannot be optimized simultaneously
Solution Approach 1:
The thread form incorporates varying cross-sectional areas at different locations to optimize local functions. The major portion with larger cross-sectional area provides structural integrity and fixation stability, while the minor portion with smaller cross-sectional area promotes bone integration and allows tissue protection, achieving optimal performance at each location rather than uniform performance throughout.
Solution Approach 2:
The minor portion of the thread form is configured to promote bone integration, which may involve porous or trabecular structures that facilitate bone ingrowth and biological integration. This porous structure in the minor portion enhances bone integration while the solid structure in the major portion maintains mechanical strength, resolving the contradiction between bone integration and structural integrity.
Data Source
AI summary
A bone screw comprising a shaft having a wall, the wall including a minor diameter and at least one thread having an external thread form. The thread form including a first portion comprising a crest of the thread form and a second portion extends between a minor diameter of the thread form and the first portion. The first portion having a solid configuration relative to the second portion. In some embodiments, systems, spinal constructs, surgical instruments and methods are disclosed.