Telemetric Load-Sensing for the Monitoring of Orthopedic Fracture Healing

At a Glance

Researchers at Colorado State University in collaboration with Bilkent University in Turkey have developed a system and methods to monitor orthopedic fracture healing. The system uses an electromagnetic antenna to measure changes in the near-field interference of metallic orthopedic implants due to deformation of the implants caused by mechanical loads. This measurement reports on the compliance of the fracture site and therefore the progress of healing.

Background

Currently, after orthopedic surgery, radiographs are used to monitor fracture healing. X-rays use attenuation to provide images of the bone and healing tissue, as attenuation is related to the density of the material. X-rays, however, are unable to discern if a fracture is healing properly in the early post-operative period because there is little to no mineralized tissue in the healing fracture callus (tissue). Furthermore, it would be advantageous to decrease both patient and technician unnecessary exposure to radiation.

The technology developed herein circumvents these inherent shortcomings by measuring changes in load-sharing between the stabilizing hardware and the healing tissue.

Overview

Diagnostic monitoring of bone fracture healing is critical for the detection of non-union in order to guide clinical decisions. However, current radiographic techniques are not helpful for early determination of the course of fracture healing due to limited detectable mineralization during early stages of healing, and non-unions are typically not identified or corrected until six months post-injury. Measuring fracture compliance has shown promise in monitoring early healing and predicting non-union in the acute timeframe when adjunctive therapies such as osteobiologics could be implemented with greater efficacy. Our group has developed a non-invasive, direct electromagnetic coupling (DEC) technology in which a radio frequency antenna couples with a fractured limb and implanted hardware to measure deflections resulting from an applied load, producing fracture compliance. The DEC technology has been validated in benchtop experiments and computer simulations, we have shown efficacy at determining healing outcome via in vivo animal studies, and clinical feasibility has been demonstrated in a pilot tibial fracture patient study (Figure 1). The tibial fracture study utilizes a telehealth system in which the patients obtain self-administered daily measurements at home using the DEC system. This remote monitoring system enables more frequent data collection during the critical early healing phase and reduces the need for clinical visits. The bending tests in this study were not painful for the patients, and the resulting measurements from this pilot study appear to successfully track healing over time. This technology has the potential to identify problematic fractures much earlier in the course of healing, opening the door to additional therapies and treatments to help patients return to normal faster.

Benefits

  • No internal sensor required (implant itself provides the signal)
  • Requires no alterations or additions to existing implants
  • Eliminates any regulatory approval hurdles
  • Cost effective

Applications

  • Orthopedic fracture healing monitoring
  • Detection of loosening orthopedic implants (e.g., joint replacements)
  • Research development
Last Updated: September 2023
Opportunity

Available for Licensing
TRL: 4

Inventors

Christian M Puttlitz
Kevin M Labus
Kirk C McGilvray

Reference Number
17-066
Licensing Manager

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