Bi-Spherical Shank Head Assembly for Curved Spinal Fixation

Resolve Bottlenecks,
Find Innovative SolutionsGenerate Solutions

Solution Overview

Problem

Existing spinal fixation systems face challenges in accommodating the highly curved shapes of spines, requiring complex assembly and alignment of bone screws, especially when polyaxial or uni-planar designs are needed, which can be difficult or impossible to implement due to fixed head configurations.

Innovation Solution

A modular spinal fixation system with a bi-spherical universal shank head that allows for connection with a variety of receiver sub-assemblies, providing multiplanar, monoplanar, and monoaxial functionalities, enabling flexible assembly and alignment through a common geometry that supports pivotal and non-pivotal movements, and includes features for bone debris clearance and secure connection.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of manufacture

If a fixed head configuration is used in bone screws, then the structure is simple and easy to manufacture, but the ability to accommodate highly curved spinal shapes is limited and alignment is difficult

Engineering Contradiction:

Improveease of manufactureVSAvoidadaptability to curved spinal shapes

Core Design Contradiction:

Ease of manufactureVSAdaptability or versatility

Solution Approach 1:

The bone screw assembly is divided into separate components: a receiver sub-assembly with a head portion and a shank portion. This segmentation allows the head to be positioned independently from the shank, enabling polyaxial movement and adaptation to curved spinal geometries while maintaining manufacturing simplicity for each individual component.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The receiver sub-assembly incorporates a spherical head that can pivot and rotate relative to the shank, transforming a static fixed-head design into a dynamic structure. This dynamic capability allows the bone screw to adapt to highly curved spinal shapes and achieve proper alignment in complex geometries.

Inventive Principle:

Principle #15Dynamics

2Adaptability or versatility

If polyaxial or uni-planar bone screw designs are implemented to accommodate curved spines, then adaptability to spinal geometries is improved, but assembly and alignment complexity increases

Engineering Contradiction:

Improveadaptability to curved spinal shapesVSAvoidassembly and alignment complexity

Core Design Contradiction:

Adaptability or versatilityVSDevice complexity

Solution Approach 1:

The receiver sub-assembly is designed as a universal interface that can accommodate multiple types of bone anchors and shanks through a standardized spherical head configuration. This multi-functionality reduces assembly and alignment complexity by providing a common connection mechanism that works across different spinal fixation scenarios.

Inventive Principle:

Principle #6Universality (Multi-functionality)

Solution Approach 2:

The receiver sub-assembly acts as an intermediary component between the bone anchor and the shank. It provides a standardized interface that simplifies the connection process and reduces alignment complexity by serving as a universal mediator in the assembly.

Inventive Principle:

Principle #24Intermediary (Mediator)

3Adaptability or versatility

If a modular system with universal shank heads is used, then versatility and adaptability are improved, but the number of components and assembly steps increases

Engineering Contradiction:

ImproveversatilityVSAvoidnumber of components

Core Design Contradiction:

Adaptability or versatilityVSDevice complexity

Solution Approach 1:

The universal shank head design allows a single receiver sub-assembly to interface with multiple different bone anchor types and configurations. This universality increases versatility while controlling the number of unique components, as the same receiver sub-assembly can be used across different surgical scenarios.

Inventive Principle:

Principle #6Universality (Multi-functionality)

Data Source

PatentUS20250375222A1Spinal fixation system with receiver and insert sub-assemblies for connecting with bi-spheric universal shank heads

Publication Date: 2025.12.11 JACKSON CORP

AI summary

A spinal fixation system includes a plurality of receiver sub-assemblies and bone anchors with shank heads, with each receiver sub-assembly including a receiver having a channel for receiving a rod and a base defining a cavity in communication with the channel to define a central bore. Each receiver sub-assembly also includes a retaining structure positionable in the cavity for frictionally engaging and articulating with an upper partial spherical surface of a shank head. Each receiver sub-assembly further includes an insert sub-assembly positionable within the central bore above the retaining structure, with the insert sub-assembly including a support collar with outer surfaces for engaging interior surfaces of the central bore, a load saddle supported by the support collar with an upper surface for engaging the elongate rod, and a clamp positioner also supported by the support collar with curvate inner surfaces for engaging the retaining structure before and after it frictionally engages the shank head.