AO Smart Socks

Strategy Fund resources are supporting a "smart socks" project that aims to change the standard for weight-bearing in patients with fractures of the pelvis and lower extremities. The idea is simple: by monitoring and recording the weight borne by the fractured limb, swelling during weight bearing, and increased warmth during exercise, "smart socks" (with built-in sensors) would change the way these fractures are treated and get patients up and mobile more quickly in the future.

Initiated by Prof Peter Brink, a retired AO Trauma faculty member and former Chairman of Traumatology at Maastricht University Medical Center (MUMC) in the Netherlands, this project began in early 2015. Like many AO Strategy Fund (AOSF) projects, it originated in surgeons’ passion for improving patient care by solving pressing clinical problems.

‘Why not listen to our patients?’

“Dr Brink and I were dissatisfied with the standard procedure of mobilizing patients only after a long period—three months. When surgeons look at the literature and even talk with one another, there is no evidence to support not bearing weight on the fracture for three months,” said AO Trauma faculty member Prof Martijn Poeze, MD, who was Brink’s chief collaborator throughout the "smart socks" project and became project leader upon Brink’s retirement in 2017. “Our patients weren’t usually complying with this instruction and they were weight bearing without our approval. They needed to get on with their lives. We thought, ‘Why not listen to our patients and have them weight bear on their own when it is permitted for them?'”

With AO Strategy Fund support, as well as federal funding from the Netherlands government, the "smart socks" team at the AO developed a protocol including red flags for detecting possible problems during weight bearing and enlisted the Departments of Instrument Development, Engineering & Evaluation (Jos Aarts, PDEng) and Movement Sciences (Dr Kenneth Meijer) at MUMC, the Department of Knowledge Engineering at Maastricht University (Dr Joël Karel), and the Department of Industrial Design at Eindhoven University of Technology (Prof Panos Markopoulos) to design the technical prototype.

“We knew there were 'smart socks' commercially available and that there were possibilities for shoe insoles, but the insoles really only measure weight bearing, which is not the only factor impacting healing,” Poeze explained. “We wanted to develop a wearable device that monitors and measures the relevant parameters and is not dependent on what kind of shoes the patient wears, because patients usually have more than one pair of shoes. Our question was, ‘Can we develop a sock that we can use for an increased weight bearing regimen that is sooner than the standard recommendation?’”

Integrated monitoring

AO AO Strategy Fund believe the result, which could reach the market as a prototype in two years' time, will be a sock that delivers integrated monitoring through the interaction of relevant parameters. Each sock has a temperature sensor, two bands of edema sensors, five pressure-point sensors, a gyroscope and an accelerometer. The project team has also tested the sock, analyzed walking quality after fractures and how it develops over time, and has investigated the clinical importance of measuring temperature and edema in patients with fractures of the lower extremities. To date, the project has been the subject of several scientific papers, and additional publications will follow later this year.

Aiming for a paradigm shift

Poeze’s team has also developed a pilot smartphone app that would allow patients to monitor their own progress, walking quality, temperature curve and foot edema, offering the potential for greater patient autonomy over their own recovery.

“We see huge commercial potential for the AO's smart socks, not only as a guide for surgeons and physiotherapists but as a contributor to patients’ improved quality of life and greater independence,” said Poeze. “We really aim for a paradigm shift: allowing patients to weight bear sooner, thanks to evidence gathered by the smart socks the AO is developing as a monitoring device. Some further development of the socks is still needed, but the direction is set."