Deformable Set Screw for Bone Fixation

Resolve Bottlenecks,
Find Innovative SolutionsGenerate Solutions

Solution Overview

Problem

Set screws used to attach elongated members to bones often experience incomplete contact, leading to loosening, back-out, and potential damage to the elongated member due to their configuration allowing various angular positions, which results in notching or deformation.

Innovation Solution

Incorporating a deformable member made from superelastic materials, such as polyetheretherketone (PEEK), attached to the set screw, which deforms to fully engage the elongated member, preventing back-out and damage by increasing contact surface area and distributing forces evenly.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Adaptability or versatility

If the receiver is configured to allow the elongated member to be positioned at a variety of angles, then the adaptability of the fastener is improved, but the contact between the set screw and the elongated member becomes incomplete, leading to loosening and back-out

Engineering Contradiction:

Improveangular positioning capabilityVSAvoidset screw retention

Core Design Contradiction:

Adaptability or versatilityVSReliability

Solution Approach 1:

The set screw incorporates a deformable member that can dynamically adjust its shape and contact surface area based on the angular position of the elongated member. This dynamic adaptation ensures continuous contact and secure retention regardless of the angle at which the elongated member is positioned within the receiver.

Inventive Principle:

Principle #15Dynamics

Solution Approach 2:

The deformable member changes its physical parameters (shape, contact area, flexibility) in response to the angular positioning of the elongated member. By altering these parameters, the set screw maintains reliable contact and prevents loosening while accommodating various angular positions.

Inventive Principle:

Principle #35Parameter changes

2Manufacturing precision

If the set screw uses a rigid contact surface, then the manufacturing precision is improved, but the contact with the elongated member at various angles becomes incomplete, causing damage to the elongated member

Engineering Contradiction:

Improveset screw fabrication accuracyVSAvoidnotching or deformation of elongated member

Core Design Contradiction:

Manufacturing precisionVSObject-affected harmful factors

Solution Approach 1:

The set screw employs a deformable member that acts as a flexible element between the rigid set screw body and the elongated member. This flexible member conforms to the elongated member's surface at various angles, distributing contact forces evenly and preventing localized stress concentrations that would cause notching or deformation.

Inventive Principle:

Principle #30Flexible shells and thin films

Solution Approach 2:

The deformable member changes its shape and contact characteristics based on the angular position and surface geometry of the elongated member. This parameter adaptation allows the set screw to maintain precise engagement without inflicting harmful stresses on the elongated member, regardless of positioning angle.

Inventive Principle:

Principle #35Parameter changes

3Device complexity

If the set screw is designed with a fixed contact point, then the device complexity is reduced, but the contact surface area is insufficient, leading to high stress concentrations and potential failure

Engineering Contradiction:

Improveset screw structureVSAvoidcontact strength

Core Design Contradiction:

Device complexityVSStrength

Solution Approach 1:

The set screw incorporates a deformable member that dynamically expands its contact surface area based on the engagement conditions. This dynamic expansion provides sufficient contact area to distribute stresses effectively while maintaining a relatively simple overall device structure that can be manufactured efficiently.

Inventive Principle:

Principle #15Dynamics

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 deformable member ensures secure attachment of the elongated member within the fastener, preventing loosening and damage, while accommodating various angular positions and ensuring stable fixation.

Implementation Method 1

A deformable member made from superelastic materials, such as polyetheretherketone (PEEK), attached to the set screw, which deforms to fully engage the elongated member

Methodology Applied

Scientific EffectSuperelasticity: Pseudoelasticity

Data Source

PatentUS8057523B2Set screw with deformable member

Publication Date: 2011.11.15 WARSAW ORTHOPEDIC INC

AI summary

The present application is directed to set screws used with fasteners to capture and engage an elongated member. The set screws include a body sized to attach to a receiver of the fastener. A deformable member may be attached to an end of the set screw and provides for the set screw to more fully engage the elongated member to prevent potential damage to the elongated member and prevent the set screw from backing out of the fastener. In one embodiment, just the deformable member contacts the elongated member. In another embodiment, the deformable member and the body contact the elongated member. In yet another embodiment, a contact member is attached to the deformable member to contact against the elongated member.