Subcutaneous Ratchet Bone Distraction for Small-Bone Lengthening

Resolve Bottlenecks,
Find Innovative SolutionsGenerate Solutions

Solution Overview

Problem

Existing bone lengthening techniques are invasive, complex, and unsuitable for small bones, often leading to complications and are not cost-effective for smaller bones such as those in children or adults.

Innovation Solution

A subcutaneous bone distraction device with a push-button expansion system and modular actuators, utilizing shape memory alloys and sensors for controlled, incremental bone lengthening, suitable for small bones.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If external fixation with complex scaffold arrays is used, then bone segments can be distracted apart, but the procedure becomes invasive and bulky with multiple skin penetrations

Engineering Contradiction:

Improvebone lengthening effectivenessVSAvoidscaffold array complexity

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The device divides the bone lengthening function into two separate block portions (first block portion and second block portion) that can be anchored to different bone segments. These blocks are connected through a ratchet mechanism that allows controlled distraction while maintaining structural integrity, eliminating the need for complex external scaffolds.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The second block portion is designed to slidably mate with and nest within the first block portion through opposing rails. This nested configuration allows the distraction mechanism to be contained within a compact structure that anchors to bone segments without requiring bulky external frameworks.

Inventive Principle:

Principle #7Nested doll (Nesting)

2Manufacturing precision

If motorized intramedullary nails with implanted antennas are used, then bone can be lengthened in controlled manner, but surgical procedure becomes more invasive and complex

Engineering Contradiction:

Improvecontrolled bone lengtheningVSAvoidimplanted motor and antenna system

Core Design Contradiction:

Manufacturing precisionVSDevice complexity

Solution Approach 1:

The patent replaces motorized actuation systems with a passive mechanical ratchet and pawl mechanism. The ratchet sections with teeth and locking pawls provide controlled unidirectional movement through pure mechanical means, eliminating the need for implanted motors, batteries, and communication antennas while maintaining precise control over bone distraction.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

The ratchet mechanism automatically maintains the distracted position through its one-way locking action. Once the blocks are distracted to the desired separation, the ratchet teeth engage with the pawls to prevent reverse movement, providing self-maintaining controlled lengthening without requiring continuous active control systems.

Inventive Principle:

Principle #25Self-service

3Reliability

If large electromagnets are used for electromagnetic distraction, then bone can be lengthened, but the device becomes bulky and invasive

Engineering Contradiction:

Improvebone distraction capabilityVSAvoidelectromagnet size

Core Design Contradiction:

ReliabilityVSVolume of moving object

Solution Approach 1:

The patent eliminates electromagnetic actuation entirely in favor of a compact mechanical ratchet system. The distraction force is applied mechanically through the ratchet and pawl engagement rather than through bulky electromagnets, achieving the same bone lengthening function with a much smaller, less invasive device profile.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

4Reliability

If existing distraction devices are used on small bones, then bone lengthening can be achieved, but the procedure becomes significantly more difficult and risky

Engineering Contradiction:

Improvebone lengthening successVSAvoiddifficulty for small bones

Core Design Contradiction:

ReliabilityVSEase of operation

Solution Approach 1:

The device is designed with block portions of reduced size and mass that are specifically suited for anchoring to smaller bone segments. The ratchet mechanism and sliding connection are scaled appropriately for small bone applications, making the procedure equally effective and safe for both large and small bones.

Inventive Principle:

Principle #3Local quality

Solution Approach 2:

The patent changes the size parameters of the distraction device components to be suitable for small bones. The block portions, rails, and ratchet sections are designed with dimensions appropriate for pediatric and small adult bones, eliminating the difficulty and risk associated with adapting large-bone devices to small applications.

Inventive Principle:

Principle #35Parameter changes

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

Provides a less invasive, cost-effective method for elongating small bones by allowing controlled, incremental expansion with reduced complications and improved suitability for smaller bones.

Implementation Method 1

utilizing shape memory alloys and sensors for controlled, incremental bone lengthening

Methodology Applied

Scientific EffectShape memory alloy: Shape Memory Alloy

Data Source

PatentUS12419626B2Bone distraction devices and methods of using same

Publication Date: 2025.09.23 NUVASIVE INC

AI summary

The present disclosure provides implantable bone distraction devices and methods of using same to elongate a bone.