2025 ISAKOS Congress in Munich, Germany

2025 ISAKOS Biennial Congress Paper


The Validity of a Smartphone App (myrecovery©) to Serve as Proxy for Exposure Time and Activity Level in Functionally Active Patients with Knee OA and Young Athletes Post ACL Reconstruction

Nicole Bryant, BMSc (Candidate), London, Ontario CANADA
Alan Getgood, MD, FRCS(Tr&Orth), DipSEM, Doha QATAR
Kevin R. Willits, MD, FRCS, London, ON CANADA
Robert Litchfield, MD, FRCSC, London, ON CANADA
J. Robert Giffin, MD, FRCSC, MBA, London, ON CANADA
Ryan M. Degen, MD, FRCSC, London, ON CANADA
Dianne M. Bryant, PhD, London, ON CANADA

University of Western Ontario, London, Ontario, CANADA

FDA Status Not Applicable

Summary

The myrecovery© smartphone app is a good predictor of activity in an OA population but is less accurate for predicting activity in a post-ACLR population.

Abstract

Background

When investigating the effectiveness of interventions to prevent recurrence of sport injuries, it is critical to measure exposure time and return-to-activity. Traditional methods like recording minutes at risk during sport participation does not capture athletes’ activities outside of their formal sport, and there is often poor adherence to completing self-report diaries. Smartphone apps that track step count may serve as a feasible proxy.

Purpose

To determine whether the myrecovery© Smartphone app can be used as a valid proxy for activity for patients with knee osteoarthritis (OA) and anterior cruciate ligament reconstruction (ACLR) surgery, by evaluating the association between activity parameters measured by the app and detailed self-report activity journals.

Methods

We prospectively selected 200 active patients (patients with OA or patients at least 9 months following ACLR), of various sex, age, sport, and activity level. Participants tracked their daily exposure to activity for 4 weeks and utilized the myrecovery© app for the same period. Participants were encouraged to carry their phone unless not permitted by their sport/activity. Activities from the diaries were converted to metabolic equivalent of task (1kcal/kg/hr) per minute (MET/min). After the 4-week period, patients competed a Marx Activity Rating Scale (MARX) to denote their activity intensity over the past month. To investigate the association between activity measures, we constructed scatterplots and used Pearson’s r for linear data. Associations were interpreted as follows; poor: < 0.2, fair: 0.2 < 0.4, moderate: 0.4 < 0.6, strong: 0.6 < 0.8, very strong: 0.8 < 1.0.

Results

We consented 100 OA patients (39% female; age 58 ± 8 years) and 100 post-ACLR patients (43% female; age 25 ± 8 years). The average association between MET/min and step count for the 4-week period was r = 0.51, p = 0.002 for the OA group and r = 0.40, p = 0.03 for the ACL group. The association between MET/min and MARX for the 4-week period was r = 0.01, p = 0.95 for the OA group and r = 0.45, p = 0.01 for the ACL group.

Conclusion

Associations between self-reported activity journals (MET/min) and app data (step count) were statistically significant for both groups, however the correlation was stronger for the OA patients compared to the ACLR patients, likely due to ACLR patients’ limited ability to carry their phones during sport. There was also a strong association between MET/min and MARX scores (both self-reported) in the ACLR group, but the correlation between these measures for the OA group was very weak. The type of activities being performed should be considered when determining the optimal method of measuring exposure. An activity score like the MARX may be a more valid measure for highly active patients participating in sport, such as those undergoing ACLR, whereas a Smartphone based app measuring step count such as myrecovery© may be preferred for older, less active patients with OA.