Polyaxial Bone Screw Notch Angulation

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Solution Overview

Problem

Existing polyaxial bone screws in spinal surgery lack sufficient angulation options, which can limit the flexibility and stability of spinal fixation procedures.

Innovation Solution

A polyaxial bone screw device featuring a screw housing with a notch that allows for increased angulation of the screw relative to the screw housing, combined with a spring that maintains the screw in an angled position, enabling greater pivotal movement and flexibility.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Adaptability or versatility

If a conventional polyaxial bone screw design is used, then the screw can be inserted into bone and secured with a housing, but the angulation options are limited

Engineering Contradiction:

Improveangulation optionsVSAvoidscrew housing structure

Core Design Contradiction:

Adaptability or versatilityVSDevice complexity

Solution Approach 1:

The screw housing is segmented into distinct functional zones: a notched portion that defines angular positions, a spring mechanism that provides frictional engagement, and a bore that receives the screw. This segmentation allows each component to contribute specifically to achieving multiple angulation options while maintaining overall structural integrity.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The screw housing incorporates a dynamic spring mechanism that allows the screw to pivot freely during insertion, then maintains selected angular positions through frictional engagement. The spring can be compressed to allow movement and releases to lock the screw at desired angles, providing adaptability without requiring a completely rigid complex structure.

Inventive Principle:

Principle #15Dynamics

2Adaptability or versatility

If the screw is fixed at a single angle, then the structure is simple, but the flexibility for different anatomical conditions is reduced

Engineering Contradiction:

Improveflexibility for anatomical conditionsVSAvoidpivotal movement mechanism

Core Design Contradiction:

Adaptability or versatilityVSDevice complexity

Solution Approach 1:

The spring mechanism automatically provides frictional engagement to maintain the screw at selected angular positions without requiring additional locking components or complex control systems. The system self-regulates by allowing free movement during insertion, then self-locks at desired angles through the spring's elastic properties and frictional contact.

Inventive Principle:

Principle #25Self-service

3Manufacturing precision

If increased angulation is enabled through a notched housing, then precision and stability of fixation are improved, but the manufacturing complexity increases

Engineering Contradiction:

Improveprecision of spinal fixationVSAvoidnotched screw housing fabrication

Core Design Contradiction:

Manufacturing precisionVSEase of manufacture

Solution Approach 1:

The notched housing incorporates localized geometric features (notches) at specific positions around the housing circumference that define precise angular orientations. These notches are concentrated in critical areas where angular positioning is needed, rather than requiring complex features throughout the entire housing structure, thereby improving manufacturing precision while controlling fabrication complexity.

Inventive Principle:

Principle #3Local quality

Applied Scientific Principles

This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.

Function Achieved in This Case

The device provides enhanced angulation options, allowing for more precise and stable spinal fixation, which can improve surgical outcomes and accommodate varying anatomical conditions.

Implementation Method 1

The polyaxial bone screw device may include a spring that is positioned to frictionally engage the screw to maintain the screw in an angled position relative to the screw housing

Methodology Applied

Scientific EffectFriction: Friction

Data Source

PatentUS12262923B2Polyaxial bone screw with increased angulation

Publication Date: 2025.04.01 VB SPINE LLC

AI summary

A polyaxial bone device includes a screw, a screw housing, and a spring. The screw includes a screw head and a shaft that extends from the screw head. The screw housing defines a longitudinal axis and a bore that extends along the longitudinal axis. The screw housing includes a basewall and opposed sidewalls that extend from the basewall. The basewall defines a notch that receives the shaft to increase pivotal movement between the screw and the screw housing relative to the longitudinal axis of the screw housing. The opposed sidewalls define a rod-receiving channel. The screw housing defines a transverse hole in communication with the bore. The spring is supported in the transverse hole and extends therethrough. The spring extends into the bore to frictionally engage the screw head while the screw head is seated in the bore.