Smart External Fixator Speeds Bone Healing Through Automated Precision Movement

At a Glance

Researchers at Colorado State University have developed an automated external fixation system that improves bone healing after major injuries. The device uses small motors and sensors to move bone segments with precise timing and force—no manual adjustments needed. By automating this process, the system reduces patient error and shortens recovery time. It also adapts to individual healing rates, offering a personalized approach to bone regeneration.

Background

Critical bone defects from trauma, cancer surgery, or infection are difficult to treat and often result in long hospital stays and repeat surgeries. Traditional bone transport methods rely on manual adjustments that can be inconsistent and disruptive to healing tissues. This new technology replaces manual manipulation with a programmable, motor-driven system that optimizes bone movement and healing efficiency. The approach represents a significant step toward intelligent orthopedic devices that enhance recovery outcomes and patient comfort.

Overview

This automated bone transport device builds upon known circular external fixation system but replaces manual turning of screws with a compact, detachable motor and lead screw assembly. The system moves a bone segment in micrometer-scale steps, precisely controlled by an Arduino-based circuit and real-time clock. Users can program distraction rate, frequency, and timing, with confirmation alerts automatically sent when movement occurs.

In laboratory and preclinical ovine studies, the CSU design demonstrated mechanical reliability and accurate movement across 30 mm bone defects. The single-motor configuration generated distraction forces up to 160 N, comparable to forces seen in clinical settings, while reducing size, weight, and cost compared to dual-motor systems. Bone healing restored up to 80% of normal bone volume and 70% of stiffness in preclinical testing. An optional strain gauge system enables the device to automatically adjust movement rates based on real-time tissue resistance, offering personalized, data-driven healing control.

Figure 1: Radiographs demonstrating bone transport in an ovine metatarsal model using the proposed device. The red box highlights the transport segment, the red arrow indicates transport direction, and the green box shows the regenerated bone. Radiographs were taken at the beginning (A), middle (B), and end (C) of the distraction phase, as well as 6-months after the end of distraction (D).

Figure 2: Ex vivo data (bending stiffness, bone volume, and bone density) for both the 3cm defect and the docking site where the transport bone contacted the proximal end of the defect. Data are presented as a percentage of the corresponding intact value measured from the untreated metatarsal.

Benefits

Automates bone transport to eliminate manual adjustment errors
Enables high-frequency, precise micromovement for improved bone regeneration
Customizable to individual patient healing rates through force feedback control
Lightweight, battery-powered design enhances comfort and portability
Wireless feedback confirms successful operation for clinicians and patients
Modular and detachable motor unit simplifies surgical workflow and reuse

Applications

Orthopedic surgery for large bone defect repair
Post-traumatic and post-tumor reconstructive procedures
Veterinary orthopedics for limb regeneration in large animals
Development of smart, sensor-integrated orthopedic devices
Research tool for studying mechanobiology and bone healing optimization

Last Updated: October 2025

Opportunity

Available for Exclusive Licensing, Collaboration or Funding

IP Status

US Provisional Patent

Inventors

Chloe Brekhus
Ben Gadomski

Reference Number

2024-080

Licensing Manager

Steve Foster
Steve.Foster@colostate.edu
970-491-7100