Anti-splay Spinal Fixation Head with Rotating Locking Component
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing spinal fixation systems face challenges in preventing splay of receiver arms over time, leading to undesirable cost, form factor issues, and strength concerns, despite attempts to mitigate splay through thread configurations and cap installations.
Innovation Solution
An anti-splay head and set-screw arrangement featuring a receiver with locking channels and a set screw with an intermediate locking component that rotates to secure the arms, preventing them from splaying by engaging with the locking channels and securing the spinal rod.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If receiver and set-screw threads are configured with sloping thread faces to hold arms inward, then splay is limited, but manufacturing complexity and cost increase
Solution Approach 1:
The receiver is divided into separate functional components: arms for rod reception and locking channels for splay prevention. The locking channels are distinct structural features separate from the threading mechanism, allowing independent optimization of each function without complex integrated thread designs.
Solution Approach 2:
The locking channels act as intermediary structures that provide a mechanical constraint against splay forces. These channels work in conjunction with the set screw to create a multi-stage locking system where the channel provides initial geometric constraint and the screw provides final securement.
2Stability of the object's composition
If caps are installed around receiver arms to prevent splaying, then arm splay is restrained, but implant size and form factor are compromised
Solution Approach 1:
The anti-splay locking channels are merged directly into the receiver structure itself, eliminating the need for separate cap components. This integration maintains the compact form factor while providing the necessary geometric constraint against splay forces.
Solution Approach 2:
Instead of adding external caps to constrain the arms, the design inverts the approach by creating internal locking channels within the receiver that actively guide and constrain arm movement. The constraint comes from within the receiver structure rather than from external additions.
3Reliability
If locking channels are made deeper to improve locking engagement, then reliability increases, but manufacturing complexity and material usage increase
Solution Approach 1:
The locking channels are designed with sufficient depth to provide reliable engagement for the intended range of motion and loading conditions, but not excessively deep. This partial action approach provides adequate reliability for normal physiological loads without the increased complexity and material usage that would result from overly deep channels.
Data Source
AI summary
An anti-splaying system having a base, first and second arms, first and second locking channels. Each of the first and second locking channels is formed in a respective one of the arms, from a proximal opening to a proximal bottom at or adjacent a proximal beginning of an inner thread in the arm. The system can instead or also include a set screw having a driving portion, a body portion, external threads extending from the body portion, and an intermediate locking component connected rotatably to the body portion. The intermediate locking component and the channels are configured such that the locking component can, in operation of the system, be moved into a securing position in the locking channels and, when in the secured position, fixes the two arms from splaying away from each other. The technology also includes methods for making the system or components thereof.