Faceted Bone Screw Thread Design for Torque Reduction

Solution Overview

Problem

Existing orthopedic screws face issues such as bone splitting during insertion due to high torque requirements and potential loosening post-installation, which can lead to mis-setting of bones and require additional procedures.

Innovation Solution

The faceted bone screw design reduces friction by incorporating facets with varying depths and angles in the thread, allowing for lower torque insertion and improved osteointegration to prevent backing out, manufactured using controlled vibratory effects or milling processes.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of manufacture

If a conventional bone screw with uniform thread depth is used, then the screw can be manufactured with simple processes, but high torque is required during insertion which causes bone splitting

Engineering Contradiction:

Improvethread manufacturing simplicityVSAvoidbone splitting

Core Design Contradiction:

Ease of manufactureVSObject-affected harmful factors

Solution Approach 1:

The patent applies local quality by varying the thread depth along the longitudinal axis of the screw. The thread depth transitions from a first depth at the distal end to a second depth at the proximal end, creating different local thread characteristics that reduce friction and torque requirements during insertion, thereby preventing bone splitting while maintaining manufacturability through controlled deformation processes

Inventive Principle:

Principle #3Local quality

Solution Approach 2:

The patent employs dynamics by introducing controlled deformation during thread formation that creates a non-uniform thread profile. The deformation process dynamically adjusts the thread geometry along the screw length, with the degree of deformation varying by position to optimize friction reduction and torque characteristics during the insertion process

Inventive Principle:

Principle #15Dynamics

2Ease of manufacture

If a conventional bone screw with uniform thread depth is used, then the manufacturing process is simple, but the screw may loosen or back out after installation

Engineering Contradiction:

Improvethread manufacturing simplicityVSAvoidscrew stability

Core Design Contradiction:

Ease of manufactureVSReliability

Solution Approach 1:

The patent applies local quality by varying the thread depth along the longitudinal axis of the screw. The thread depth transitions from a first depth at the distal end to a second depth at the proximal end, creating different local thread characteristics that reduce friction and torque requirements during insertion, thereby preventing bone splitting while maintaining manufacturability through controlled deformation processes

Inventive Principle:

Principle #3Local quality

Solution Approach 2:

The patent employs dynamics by introducing controlled deformation during thread formation that creates a non-uniform thread profile. The deformation process dynamically adjusts the thread geometry along the screw length, with the degree of deformation varying by position to optimize friction reduction and torque characteristics during the insertion process

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

This design reduces the torque required for screw insertion by up to 50% and enhances stability by acting as anchors within the bone, minimizing the likelihood of screws loosening and breaking free during removal.

Implementation Method 1

forming a plurality of facets in the thread during the cutting by imparting a controlled vibratory effect on the bar stock and a cutting head

Methodology Applied

Scientific EffectVibration: Vibration

Implementation Method 2

improved osteointegration between the faceted threaded portion of the implanted device and the bone

Methodology Applied

Scientific EffectOsteointegration:

Data Source

PatentEP2219812B1Method for manufacturing a bone screw

Publication Date: 2017.01.04 MEDICAL FACETAB

AI summary

A faceted bone screw and a method for manufacturing the same includes a screw thread configuration having facets that are substantially transverse to the thread. The facets are generally made up of a plurality of transitioning peaks and valleys which vary the depth of the thread and are disposed in one or more locations throughout the threaded portion of the bone screw. The facets operate to reduce the torque required to drive the bone screw into bone, while at the same time operate to assist in anchoring the bone screw within the bone once inserted therein, and thereby reduce the possibility for the screw backing out after insertion.