Bone Screw Porous Structures for Sacroiliac Fixation

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Solution Overview

Problem

Existing bone screws lack effective structures and manufacturing methods to promote bone growth and are not optimally designed for fixation at the sacroiliac joint.

Innovation Solution

A bone screw with a roughened surface, overhanging thread portions, and internal channels is manufactured via 3-D printing, specifically using Direct Metal Laser Sintering (DMLS) with Titanium Alloy, featuring porous structures and windows for enhanced bone integration and growth.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If traditional bone screws are manufactured using conventional methods, then manufacturing processes are simpler, but bone growth promotion and fixation effectiveness are insufficient

Engineering Contradiction:

Improvebone growth promotionVSAvoidscrew structure

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The bone screw incorporates porous structures on its surface and internal voids that promote bone ingrowth and fusion. The porous coating on the screw surface provides mechanical interlocking with bone tissue, while internal channels allow bone graft material to be delivered and grow through the screw, directly addressing the need for improved bone growth promotion.

Inventive Principle:

Principle #31Porous materials

Solution Approach 2:

The screw thread is divided into multiple segments with different properties: coarse external threads for bone purchase, fine internal threads for bone growth, and intermediate overhanging portions that create channels for bone graft delivery. This segmentation allows each portion to perform its specific function optimally.

Inventive Principle:

Principle #1Segmentation

2Reliability

If bone screws are designed with complex features for bone growth promotion, then fixation effectiveness improves, but manufacturing complexity and cost increase

Engineering Contradiction:

Improvefixation effectivenessVSAvoidmanufacturing process

Core Design Contradiction:

ReliabilityVSEase of manufacture

Solution Approach 1:

The patent utilizes 3-D printing technology to manufacture the bone screw with precisely controlled geometric parameters, including thread pitch, pore size, and channel dimensions. By changing manufacturing parameters through additive manufacturing, complex structures are created without traditional machining operations, maintaining ease of manufacture while achieving superior fixation.

Inventive Principle:

Principle #35Parameter changes

3Strength

If conventional screw designs are used, then manufacturing is easier, but bone integration and fusion are insufficient

Engineering Contradiction:

Improvebone fusionVSAvoidscrew structure

Core Design Contradiction:

StrengthVSDevice complexity

Solution Approach 1:

The bone screw features nested structures where internal channels and pores are incorporated within the screw body. The screw contains hollow channels that can accommodate bone graft material, and porous surfaces that allow bone tissue to penetrate and integrate with the screw structure, creating a nested architecture that enhances bone fusion.

Inventive Principle:

Principle #7Nested doll (Nesting)

4Reliability

If traditional manufacturing methods are used, then production costs are lower, but structural integrity and bone growth promotion are compromised

Engineering Contradiction:

Improvestructural integrityVSAvoidmanufacturing method

Core Design Contradiction:

ReliabilityVSEase of manufacture

Solution Approach 1:

The patent replaces traditional mechanical manufacturing processes (machining, milling, drilling) with 3-D printing technology. This substitution allows for the direct creation of complex internal structures, porous surfaces, and precise geometric features that maintain structural integrity while promoting bone growth, without requiring multiple manufacturing steps.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

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 bone screw facilitates improved bone fusion and growth by providing a receptive surface and internal features that enhance fixation at the sacroiliac joint, reducing manufacturing costs and labor while maintaining structural integrity.

Implementation Method 1

manufactured by 3-D printing, specifically using Direct Metal Laser Sintering (DMLS) with Titanium Alloy

Methodology Applied

Scientific EffectDirect Metal Laser Sintering: Selective Laser Sintering

Data Source

PatentUS12433653B2Bone screws

Publication Date: 2025.10.07 CHOICE SPINE LLC

AI summary

A bone screw includes a screw body having a head at one end of the screw and a tip at an opposite end of the screw; head threads directly attached to the screw body and continuous around the head of the screw; tip threads directly attached to the screw body and continuous around the tip of the screw; and overhanging thread portions between the head threads and the tip threads, the overhanging thread portions spaced apart, with unthreaded channels between the overhanging thread portions and the overhanging thread portions overhanging a portion of the unthreaded channels.