Ambulant physical activity monitoring gains relevance in clinical research

Issue: July 2017

The clinical relevance of physical activity for general health and wellbeing is increasingly being recognized, culminating in campaigns proclaiming, “Activity is the medicine of the 21st century,” or for the opposite, inactivity or sedentary lifestyles, declaring, “Sitting is the new smoking,” in health promotion programs.

Recent evidence shows inactivity is a major risk factor, while increased activity is an effective intervention or component for reduced cardiovascular disease (-35%), breast cancer (-20%), diabetes (-40%) and other disease, including orthopaedic-related conditions like fall risk (-68%). Besides the quantitative influence of physical activity, qualitative parameters of activity have shown clinical relevance with examples in an orthopaedic context cadence (steps/minute as a proxy for walking speed) or turning velocity being strongly correlated with fall risk.

Physical activity and orthopaedics

In orthopaedics, activity monitoring seems of particular value, as disease and intervention directly affect the movement apparatus and activity is recognized as a factor in preventing, delaying or triggering pathology or trauma. Thus, objectively measured quantitative levels and qualitative aspects of activity are increasingly investigated as a tool for epidemiological studies, diagnosis, indication, outcome assessment, personalized medicine or patient coaching.

For example, in a recent award-winning paper by Norden and colleagues and a similar study presented at EFORT 2017 by Stoffels and colleagues, it was shown that spinal stenosis is associated with activity levels that were so low compared to health guidelines defining them as sedentary behavior, that detrimental health effects must be expected.

A leg-worn accelerometer used for clinical grade activity monitoring in the free field is shown.

In another study by Moonen and colleagues, patients with a primary unilateral unicompartmental knee arthroplasty were hardly more active walking in general than matched TKA patients, but they walked significantly more slopes and stairs, in particular descending.

Technology and methods

The recognition of physical activity in health and orthopaedics and the emergence of related evidence has been driven by enabling technology. Wearable sensors, mainly accelerometers, but increasingly also fused with other modalities, like, gyroscopes, are now available for multiday free-field measurement. Combined with validated signal analysis algorithms, activity classification or movement biomarker, detection has become feasible at clinically required resolution and reliability at a level which the popular, mostly wrist-worn lifestyle, activity trackers cannot offer. The increased orthopaedic interest in wearables and activity is also reflected by a recent overview in EFORT Open Reviews that was listed among its most downloaded articles, such as those by Grimm and Bolink, combining well with another hardware-focused review, such as that by Sliepen and colleagues.

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Ongoing research in orthopaedics

Funding sources, such as the European Horizon 2020 program, have recognized the activity monitoring method, for instance, in calls aimed at healthy aging or providing new clinical evidence.

In the running H2020 project KNEEMO, a training network for knee osteoarthritis (OA), activity monitors are used in patients with early stage knee OA to identify movement biomarkers for early diagnosis, to quantify its effects on activity levels and to provide an objective outcome tool for new conservative therapies developed in this consortium, including a custom brace.

In the Nordic consortium NITEP, which aims to provide new evidence comparing conservative treatment to surgical treatment for proximal humerus and wrist fractures, activity monitors are also being used in the upper extremity to collect objective data on shoulder function during daily life as additional evidence.

Outlook

With technology advancing fast and orthopaedic application still young, the field promises valuable advances, but still requires much learning and consensus building. At this year’s European Orthopaedic. Research Society Annual Meeting, which will be held 13 to 15 September in Munich, a symposium will be dedicated to this subject and will review current clinical studies, analyze the clinical relevance of activity parameters and discuss practical issues, as well as future developments.

For more information:
Bernd Grimm, PhD, MEng, immediate past-president of the EORS, can be reached at email: bp.grimm@gmail.com.

Disclosure: Grimm reports no relevant financial disclosures.