Electrical impedance detects early stages of bone healing: An in vivo explanatory study of tibial fractures in rabbits

TL;DR

This study shows that electrical impedance measurements can track bone healing in rabbits, offering a non-radiation alternative to traditional methods.

Contribution

The study introduces electrical impedance spectroscopy as a novel method for monitoring early bone healing in vivo.

Findings

Impedance measurements at 5 Hz showed a significant decrease over time during bone healing.

Impedance correlated with radiographic union scores and bone volume fraction.

Lower frequencies provided more consistent impedance trends during healing.

Abstract

Healing after bone fracture is assessed by clinical examination and frequent radiographs, which expose patients to radiation and lack standardisation. This study aimed to explore electrical impedance patterns during bone healing using electrical impedance spectroscopy in 18 rabbits subjected to tibial fracture stabilised with an external fixator.

Impedance was measured daily across the fracture site at a frequency range of 5 Hz to 1 MHz. Biweekly radiographs were analysed using modified anterior‐posterior (AP) radiographic union score of the tibia (RUST). The animals were divided into three groups with different follow‐up times: 1, 3 and 6 weeks for micro‐computer tomography and mechanical testing.

A decreasing trend in impedance was observed over time for all rabbits at lower frequencies. Impedance closest to 5 Hz showed a statistically significant decrease over time, with greatest decrease occurring during the first 7 postoperative days. At 5 Hz, a statistically significant correlation was found between impedance and the modified AP RUST score and between impedance and bone volume fraction.

This study showed that the electrical impedance can be measured in vivo at a distance from the fracture site with a consistent change in impedance over time and revealed significant correlation between increasing radiographic union score and decreasing impedance.

Not applicable.

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