Cannulated Bone Anchor with Tapered Thread Sections

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Solution Overview

Problem

Cannulated bone anchors face difficulties in starting the anchor in the proximal surface of the bone without a guide wire during open or non-minimally invasive procedures, requiring significant force or pre-threading.

Innovation Solution

A bone anchor assembly with a distal shaft featuring multiple threaded sections of varying diameters and tapers, along with an unthreaded tip, designed to facilitate easy insertion into bone surfaces, eliminating the need for pre-threading or excessive force.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Adaptability or versatility

If a cannulated bone anchor is used without a guide wire in open or non-minimally invasive procedures, then the anchor can be used in procedures without guide wire guidance, but it becomes difficult to start the anchor in the proximal surface of the bone unless pre-threading is performed or significant force is applied

Engineering Contradiction:

Improveability to use without guide wireVSAvoiddifficulty to start anchor in bone

Core Design Contradiction:

Adaptability or versatilityVSEase of operation

Solution Approach 1:

The bone anchor features a localized unthreaded tip section at the distal end, while the rest of the shaft maintains threading. This local modification allows the tip to act as a pilot that easily penetrates the bone surface without requiring pre-threading or excessive force, while the threaded sections provide secure fixation once inserted.

Inventive Principle:

Principle #3Local quality

Solution Approach 2:

The distal shaft is divided into multiple threaded sections with varying diameters and tapers, plus an unthreaded tip section. This segmentation allows different portions of the anchor to serve different functions: the unthreaded tip for easy initial insertion, and the threaded sections for progressive engagement and secure fixation.

Inventive Principle:

Principle #1Segmentation

2Ease of operation

If pre-threading or significant force is applied to start the cannulated bone anchor, then the anchor can be inserted into the bone, but additional instruments are required or excessive force is needed

Engineering Contradiction:

Improveability to insert anchorVSAvoidneed for additional instruments

Core Design Contradiction:

Ease of operationVSDevice complexity

Solution Approach 1:

The unthreaded tip section serves as a self-contained pilot that automatically facilitates its own insertion into the bone surface. The anchor is self-sufficient for starting insertion without requiring separate pre-threading instruments or excessive manual force, simplifying the overall procedure.

Inventive Principle:

Principle #25Self-service

3Reliability

If conventional cannulated bone anchors are used, then the anchor can be delivered over a guide wire, but the anchor requires pre-threading or significant force to start in the bone surface

Engineering Contradiction:

Improveguide wire delivery capabilityVSAvoiddifficulty to start anchor

Core Design Contradiction:

ReliabilityVSEase of operation

Solution Approach 1:

The localized unthreaded tip section provides a specific functional zone for easy bone penetration, while the rest of the anchor maintains its cannulated structure for guide wire compatibility. This local modification does not compromise the overall reliability of guide wire delivery while solving the insertion difficulty.

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

Enhances the ease of anchor placement in bone surfaces, reducing the need for additional instruments and minimizing soft tissue damage, while providing secure fixation.

Implementation Method 1

The distal shaft may have a first threaded section distal to a proximal head, a second threaded section distal to and adjacent the first threaded section, and a third threaded section distal to and adjacent the second threaded section

Methodology Applied

Scientific EffectMechanical threading: Screw

Data Source

PatentUS20250107832A1Bone anchors

Publication Date: 2025.04.03 MEDOS INT SARL

AI summary

A cannulated bone anchor assembly includes a bone anchor, a receiver member for receiving a spinal fixation element to be coupled to the bone anchor, and a closure mechanism to fix the spinal fixation element with respect to the receiver member. The bone anchor includes a distal shaft having a first threaded section distal to a proximal head, a second threaded section distal to and adjacent the first threaded section, and a third threaded section distal to and adjacent the second threaded section. The first threaded section having a constant major and minor diameter. The second threaded section having a tapering major and minor diameter. The third threaded section having a tapering major diameter and a constant minor diameter.