Pilot Study to Identify and Validate Digital Biomarkers in Osteoarthritis of the Knee (DigitOAK)

To date, treatment options for knee osteoarthritis remain limited, and their clinical evaluation is complex due to the day-to-day fluctuations in symptoms.

Hospital tests provide a point-in-time measurement that is influenced by various factors (fatigue, recent activity, weather, etc.), making reliable assessment difficult. The aim of the study is to assess the feasibility and acceptability of monitoring actual activity using the Syde® portable device in up to 30 subjects. Numerical variables derived from data collected by Syde® will be compared with conventional on-site clinical assessment criteria and with data from healthy participants, in order to identify a reliable and robust metric, thereby improving treatment evaluation and personalised patient management.

MAIN OBJECTIVES

• Evaluate the use of the device
• Identify numerical variables and determine the optimal time window for evaluation

Patients will have two visits: one at inclusion and a second two months later. They will wear Syde® magneto-inertial sensors, one on each ankle, for the month following the initial visit, then a Syde® sensor on the ankle and another on the wrist on the side of the non-dominant hand for the following month. The total duration of the recording period is two months.

Study Overview

• Status: Completed
• Conditions: Osteoarthritis of the Knee
• Intervention / Treatment: Device: Syde; Diagnostic test: The Self-Paced 40-meter Walk Test (SPWT); Diagnostic test: 30-second chair stand test (30s-CST); Diagnostic test: The Timed up and go test (TUG); Diagnostic test: Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC 3.1); Diagnostic test: Patient global impression of severity (PGI-S); Other: Pain Level Diary; Other: Qualitative Interview

Detailed Description

SECONDARY OBJECTIVES

• To assess external validity

  • Spearman correlation coefficient between variables and WOMAC 3.1 scores
  • Spearman correlation coefficient between results and timed tests
  • Spearman correlation coefficient between results and Kellgren-Lawrence grade

• Assess ability to discriminate between groups

  • Difference between patients and healthy participants, and between the 50% of patients with the lowest WOMAC 3.1 score and the 50% with the highest score, and overlap between groups
  • Difference between the three groups of patients according to WOMAC 3.1 score
• Collect qualitative data: Results of qualitative interviews on significant aspects of mobility and device acceptability
• Identify a stiffness index: Ratio between outcome measurements after 0.5 - 1 - 2 or 3 hours of immobility (at least) for 10 minutes and the same outcome measured over the total recording period, excluding the 10-minute intervals.

• Identify the best time of day for recording

  • The metric properties of the different variables will be calculated over the time periods 1-11; 1-10; 1-9; 1-8; 1-7; 1-6; 1-5; 1-4; 1-3; 1-2 and the first hour of the day in order to identify whether morning stiffness accentuates the difference between OAK and healthy participants.
  • The metric properties of the different variables will be calculated over the time periods 2-12; 3-12; 4-12; 5-12; 6-12; 7-12; 8-12; 9-12; 10-12; 11-12 and 12 hours of the day in order to identify whether evening fatigue accentuates the difference between OAK and healthy participants.

• Study Type: Interventional
• Enrollment (Actual): 43
• Phase: Not Applicable

Contacts and Locations

Study Locations

• Belgium
  • Liège, Belgium, 4000
    • Centre de référence des maladies neuromusculaire (CRMN Liège), Hopital de la Citadelle

Participation Criteria

Eligibility Criteria

• Ages Eligible for Study: Adult; Older Adult
• Accepts Healthy Volunteers: Yes

Description

Inclusion Criteria:

• Patients with bi- or unilateral Knee Osteoarthritis as confirmed by a qualified rheumatologist/orthopaedist or rehabilitation doctor and having had at least one X-ray or MRI for diagnosis confirmation with Kellgren-Lawrence grade minimum 1
• WOMAC 3.1 total score at screening indicating mild, moderate, or severe symptoms in the past 48 hours
• BMI below 35.0 kg/m2

Exclusion Criteria:

• Patients with significant cognitive disorders, limiting the understanding of the exercises to be performed or the presence of apparent communication difficulties hindering the correct collection of data.
• Unable to walk independently (10 meters without any type of external help)
• History of any joint replacement surgery.
• Currently undergoing or had corticosteroid injections within the past 3 weeks.
• Underwent knee surgery in the past 6 months.
• Expecting joint replacement surgery or arthroscopy within 3 months.
• Pregnant women or women planning to become pregnant during the study
• Presence of any other conditions than osteoarthritis (musculoskeletal or neurological) that may affect normal gait. OA in other joints is not considered as an exclusion criterion as long as OAK is the most significant cause of walking impairment.

Study Plan

How is the study designed?

Design Details

• Primary Purpose: Diagnostic
• Allocation: Non-Randomized
• Interventional Model: Parallel Assignment
• Masking: None (Open Label)

Number of Arms

2

Arms and Interventions

Participant Group / Arm	Intervention / Treatment
Active Comparator: Patient with osteoarthritis of the knee; Patients will have two visits: one at inclusion and a second two months later. They will wear Syde® magneto-inertial sensors, one on each ankle, for the month following the initial visit, then a Syde® sensor on the ankle and another on the wrist on the side of the non-dominant hand for the following month. The total duration of the recording period is two months.	Device: Syde; Actimyo/Syde is an innovative device intended to be used in a home-based environment. It is composed of two watch-like sensors, each containing a magneto-inertial sensors that record the linear acceleration, the angular velocity, the magnetic field of the movement in all directions.The two watches can be worn as wristwatch or placed near the ankle.; Diagnostic test: The Self-Paced 40-meter Walk Test (SPWT); Assesses walking speed over a fixed distance by having participants walk as quickly and safely as possible, but without running, along a 40-meter course.; Diagnostic test: 30-second chair stand test (30s-CST); It is a simple assessment of lower body strength and endurance. Participants are instructed to stand up and sit down from a chair as many times as possible in 30 seconds.; Diagnostic test: The Timed up and go test (TUG); During this standardized test, the subject is observed and timed while he/she rises from a chair, walks 3 meters, performs a 180° turn, walk back toward the chair and sits down.; Diagnostic test: Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC 3.1); The WOMAC is a widely used self-administered health status measure for evaluating pain, stiffness, and function in patients with osteoarthritis of the hip or knee. The WOMAC measures three separate dimensions: pain (5 questions), stiffness (2 questions) and function (17 questions).; Diagnostic test: Patient global impression of severity (PGI-S); The PGI-S is a patient-reported measure that evaluates the perceived severity of a condition based on a standardized scale, ranging from "none" to "very severe".; Other: Pain Level Diary; Patients will record their specific OAK average pain level during the day using the VAS scale of 0-10 points for one week at the beginning of each month of recording.; Other: Qualitative Interview; This interview is designed to better understand the patient's perspective on the impact of osteoarthritis of the knee on their motor function and to inform the selection of digital tools in upcoming clinical studies.
Active Comparator: Healthy Subjects; Healthy subjects with similar age and BMI to patients with osteoarthritisof the knee	Device: Syde; Actimyo/Syde is an innovative device intended to be used in a home-based environment. It is composed of two watch-like sensors, each containing a magneto-inertial sensors that record the linear acceleration, the angular velocity, the magnetic field of the movement in all directions.The two watches can be worn as wristwatch or placed near the ankle.; Diagnostic test: The Self-Paced 40-meter Walk Test (SPWT); Assesses walking speed over a fixed distance by having participants walk as quickly and safely as possible, but without running, along a 40-meter course.; Diagnostic test: 30-second chair stand test (30s-CST); It is a simple assessment of lower body strength and endurance. Participants are instructed to stand up and sit down from a chair as many times as possible in 30 seconds.; Diagnostic test: The Timed up and go test (TUG); During this standardized test, the subject is observed and timed while he/she rises from a chair, walks 3 meters, performs a 180° turn, walk back toward the chair and sits down.

What is the study measuring?

Primary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Total Recording Time Over 2 Months	Total number of hours recorded by the Syde® wearable device over a 2-month period.	2 months
Median Daily Recording Time	Median number of hours recorded per day by the Syde® device over the 2-month period.	2 months
Days to Reach 180 Recording Hours	Number of days required to reach 180 hours of recording, considered the optimal threshold for analysis.	2 months
Intra-Class Correlation of Syde® Outcomes	Intra-Class Correlation (ICC) of each Syde® outcome calculated over slices of x hours (x = 10 to 90) of data per patient to assess reliability.	Entire recording period over 2 months

Secondary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Correlation Between Syde® Variables and WOMAC 3.1 Scores	Spearman correlation between digital variables and WOMAC 3.1 scores at 2 months.	Baseline and 2 months
Correlation Between Syde® Variables and Timed Tests	Correlation between digital variables and results from 40 m self-paced test, 30 s chair stand test, and timed up and go test.	Baseline and 2 months
Correlation Between Syde® Variables and Kellgren-Lawrence Grade	Spearman correlation between digital variables and Kellgren-Lawrence grade.	Baseline
Discriminative Power of Syde® Variables	Differences in Syde® outcomes between patients and controls, and among subgroups based on WOMAC 3.1 scores.	Entire recording period over 2 months
Qualitative Interview on Mobility and Usability	Qualitative data from interviews exploring mobility limitations, important measures, and impact on daily life.	Baseline and Month 2
Stiffness Index Based on Immobility	Ratio of outcome measures after 0.5-3 hours of immobility (≥10 minutes) compared to full-day values excluding immobility periods.	Entire recording period over 2 months
Optimal Time of Day for Recording	Metric properties of outcomes calculated for various time windows (e.g., 1-11h, 2-12h) to assess morning stiffness and evening fatigue.	Entire recording period over 2 months

Collaborators and Investigators

• Sponsor: Centre Hospitalier Universitaire de Liege
• Collaborators: Centre Hospitalier Régional de la Citadelle; SYSNAV
• Investigators: Study Director: Laurent Servais, MD, PhD, Centre Hospitalier Universitaire de Liege

Study record dates

Study Major Dates

• Study Start (Actual): May 14, 2025
• Primary Completion (Actual): November 28, 2025
• Study Completion (Actual): November 30, 2025

Study Registration Dates

• First Submitted: May 15, 2025
• First Submitted That Met QC Criteria: June 19, 2025
• First Posted (Actual): June 22, 2025

Study Record Updates

• Last Update Posted (Actual): March 24, 2026
• Last Update Submitted That Met QC Criteria: March 23, 2026
• Last Verified: March 1, 2026

More Information

Terms related to this study

• Keywords: osteoarthritis of the knee; digital outcome
• Additional Relevant MeSH Terms: Musculoskeletal Diseases; Arthritis; Joint Diseases; Rheumatic Diseases; Osteoarthritis; Osteoarthritis, Knee
• Other Study ID Numbers: DigitOAK

Plan for Individual participant data (IPD)

• Plan to Share Individual Participant Data (IPD)?: UNDECIDED

Drug and device information, study documents

• Studies a U.S. FDA-regulated drug product: No
• Studies a U.S. FDA-regulated device product: No