Patient convalescing following first-in-human AO Fracture Monitor application

The novel AO Fracture Monitor System for remote monitoring of implant load

Sixty-five years after the AO was established to champion revolutionary internal fixation techniques that continue to achieve unprecedented results in fracture healing, its legacy of improving patient outcomes continues with the first-in-human application of the AO Fracture Monitor developed by the AO Research Institute Davos (ARI) with the AO’s innovation funding. In an important step toward regulatory approval, the safety of this implantable telemetric sensor system is now being validated in a multicenter clinical trial at four hospitals in Germany.

Attached to a DePuy Synthes Variable Angle LCP™ Curved Condylar Plate and implanted by BG Unfallklinik Tübingen orthopedic trauma surgeon Benedikt Braun on October 2, 2023, the AO Fracture Monitor has since been continuously monitoring the healing of a 61-year-old German patient who sustained a significantly comminuted fracture in a three-meter fall from a ladder. 

“X-rays are not especially reliable for fractures in the diametaphyseal region in terms of assessing bone healing,” Braun said, pointing out that while the data collected by the AO Fracture Monitor are currently not available to him or the patient due to the study design, which focuses on the safety of the device but does not allow that the data of the fracture monitor interfere with any treatment decision, the system ultimately will enable surgeons and their patients to continuously track load bearing right after their surgical fracture treatment. “With this system, you can get a glimpse of the fracture healing over time: If the load on the implant decreases, it means that there is more load sharing by the fracture site indicating increasing fracture consolidation. Eventually, you want the load on the plate to be zero because the bone should support all of the load. The AO Fracture Monitor will allow surgeons and patients to continuously monitor the individual healing trajectory and detect and react to healing disturbances early on, rather than waiting for x-ray or computed tomography [CT] scans at different timepoints, sometimes quite late during the treatment process.”

Braun, principal coordinating investigator for the current clinical investigation and chairperson of the AO Technical Commission (AO TC) Smart Digital Solutions Task Force, saw the patient on November 27, 2023, for his eight-week follow-up.

“He’s doing great and is very excited to be part of this study. All he has to do is check from time to time on the smartphone app that the data is transferred,” said Braun. “The patient is recovering on schedule and is happy with the treatment and study so far—but he would love to see the data, of course. My hope for this patient is that when he comes back six to eight weeks from now, he will be back to his preinjury condition.”

Many milestones

AO Research Institute Davos (ARI) Senior Project Leader Concept Development Manuela Ernst said the first-in-human application of the AO Fracture Monitor is just the latest of several milestones in the project’s history, but the most eagerly awaited one. 

The system, which represents an innovative approach to individualizing patient rehabilitation, arose from talks between former ARI Focus Area Leader Concept Development Dr. Markus Windolf and AO founding father and longtime ARI Director Prof Stephan Perren. After many design iterations and fine-tuning, and eventually formal product development, a new kind of telemetric system was created, and the development team is happy to now have an active implantable device ready for clinical application. The current clinical study got underway in autumn this year with so far two patients enrolled. Over the next months, a total of 37 patients will be recruited at the participating hospitals BG Klinik Tübingen, Universitätsklinikum des Saarlandes, Universitätsklinikum Ulm, and Universitätsklinikum Münster.

The first-in-human application of the AO Fracture Monitor is an exciting milestone, Ernst said.

“It was an incredible experience to be able to observe the first surgery and actually see how the AO Fracture Monitor was implanted in a patient after so many years of development,” she recalled. The current study is expected to conclude in spring 2025 and provide the missing data for the subsequent conformity assessment by the notified body for market approval in Europe. “We anticipate a CE mark by the end of 2025 and availability for larger clinical studies by early 2026.”


‘A full-service resource’

Braun said AO innovation funding is critical in bringing new technologies to clinicians and promoting excellence in patient care and outcomes in trauma and musculoskeletal disorders.

“The AO Fracture Monitor is revolutionary in that it represents a step away from relying on traditional modalities like x-rays and toward a much more patient specific and accurate ways of monitoring bone healing,” he said. “The AO is helping make this project possible with not only funding but expertise at every step of development. To make a great idea a reality, you need strong partners, and the AO—with the AO Innovation Translation Center, including AO's innovation funding and Clinical Evidence teams, all the way to ARI—is truly a full-service resource.”

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