Spinal Implant Threaded Opening Design for Fracture Resistance
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Solution Overview
Problem
Ceramic spinal implants, such as those made of silicon nitride, are prone to fractures and damage due to high forces applied during installation, particularly at the peripheral edges or openings where the implant engages with instruments like rods, leading to potential breakage.
Innovation Solution
The design incorporates a configuration where the highest forces are applied to the strongest areas of the implant by using a threaded section spaced apart from the peripheral edge, with reduced diameter sections and an expanded region to accommodate the installation rod, ensuring engagement with full, stronger threads rather than weaker partial threads, and optionally includes notches or fins for guidance during installation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If the threaded region is positioned at the peripheral edge of the opening for receiving the rod, then the implant can be easily engaged with the installation rod, but the high forces applied during installation cause fractures and damage to the ceramic implant
Solution Approach 1:
The patent applies local quality by creating a reinforced region with increased thickness at the location where the threaded region engages with the installation rod. This localized reinforcement strengthens the specific area subjected to high installation forces, preventing fractures while maintaining the threaded engagement functionality at the periphery of the opening.
2Reliability
If the threaded region is spaced apart from the peripheral edge to avoid weak areas, then fracture resistance is improved, but the engagement strength with the installation rod is reduced
Solution Approach 1:
The patent positions the threaded region in the reinforced area (spaced from the periphery) to avoid weak zones and prevent fractures, while simultaneously providing sufficient engagement length with the installation rod to maintain adequate engagement strength through the reinforced material.
Solution Approach 2:
The patent employs composite construction by combining a reinforced region with increased thickness containing the threaded region, creating a hybrid structure that leverages both the reinforcement for fracture resistance and the threaded engagement for strong rod connection.
3Ease of operation
If the opening is made larger to accommodate the installation rod, then the rod can be easily inserted, but the peripheral edges become more vulnerable to forces and fractures
Solution Approach 1:
The patent creates a reinforced region with increased thickness that contains the threaded region, providing localized strength enhancement to counteract the vulnerability of larger opening peripheral edges during rod insertion while maintaining ease of insertion.
Data Source
AI summary
Apparatus and systems relating to spinal implants and instruments for installing such implants. In some embodiments, the system may comprise a spinal implant, an inserter, an intermediary piece, and/or an installation rod. The spinal implant may comprise an at least partially threaded opening configured to receive the installation rod. The opening may be positioned within a fixed wall of the spinal implant, and the opening may comprise a peripheral edge defined by the wall of the spinal implant.