Arcuate Fixation Member Navigating Anatomical Obstructions
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Solution Overview
Problem
In spinal fixation systems, achieving a desired trajectory for screw insertion can be difficult due to anatomical obstructions, such as the iliac crest, which can prevent medially-directed placement of pedicle screws, leading to screw loosening and pullout.
Innovation Solution
A bone fixation member with a curved intermediate portion and a guidance member to guide the tip during insertion, allowing for non-linear insertion trajectories, and an intervertebral implant system with a spacer and insert plate configuration that accommodates arcuate fixation members for secure anchoring in vertebral bodies.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If a linear line-of-approach trajectory is used for pedicle screw insertion, then the insertion path is simple and direct, but anatomical obstructions (such as the iliac crest) can block the trajectory and prevent proper screw placement
Solution Approach 1:
The pedicle screw is designed with a curved or arcuate body that follows a non-linear trajectory through the vertebral body. This curved geometry allows the screw to navigate around anatomical obstructions like the iliac crest while still achieving proper medially-directed placement for secure fixation, resolving the contradiction between simple insertion path and anatomical adaptability
2Reliability
If medially-directed placement of pedicle screws is achieved, then screw loosening and pullout are prevented, but the iliac crest can obstruct the linear line-of-approach needed for insertion
Solution Approach 1:
The curved pedicle screw body enables insertion through a non-linear path that avoids the obstructing iliac crest while maintaining the desired medially-directed final position. This ensures reliable screw fixation stability without being blocked by anatomical structures during insertion
Solution Approach 2:
The screw design transitions from requiring a strictly linear three-dimensional insertion path to allowing a curved trajectory that incorporates spatial flexibility. This dimensional adaptation enables the screw to bypass obstructions in the insertion path while achieving the correct medially-directed placement for reliable fixation
3Reliability
If multiple screws at unique angles are used to fix intervertebral implants, then secure anchoring is achieved, but multiple lines-of-approach are required which can be difficult due to patient anatomy
Solution Approach 1:
The curved pedicle screw design serves multiple functions: it provides secure anchoring through medially-directed placement while simultaneously adapting to various anatomical configurations through its flexible curved geometry. This universal design reduces the need for multiple different screw types or complex multi-angle insertion protocols
Data Source
AI summary
Arcuate fixation members with varying configurations and/or features are provided, along with additional components for use therewith in provided intervertebral implants. The arcuate fixation members may be of different lengths, cross sectional geometries, and/or cross sectional areas. Applications of intervertebral implants utilizing arcuate fixation members are particularly suitable when a linear line-of-approach for delivering fixation members is undesirable.