Background: Hip and knee osteoarthritis (OA) are highly prevalent worldwide. The guidelines recommend physical activity and education as the core treatments for osteoarthritis. Digital health has the potential to engage people in physical activity and disease management. Therefore, we conducted a pilot trial to assess the usability and preliminary effectiveness of an app-based physical activity and education program (Join2Move) compared to usual care for people with hip and/or knee OA in Germany.

Methods: A randomized controlled pilot study was conducted. Individuals with diagnosed or self-reported knee and hip OA were included. Allocation to the intervention or control group was randomized. The intervention group received the Join2Move program. The Join2Move program was previously developed as a website and evaluated in the Netherlands. For the current study, the program was translated and adapted to the German context and adjusted from a website to an app. The control group received usual care. The primary outcomes were usability and preliminary effectiveness (pain and physical functioning). Measurements were taken at baseline and at twelve weeks. The data analysis was performed using SPSS (IBM SPSS Statistics 29.0).

Results: Sixty participants, with a mean age of 61.9 (SD ± 7.2) years, were allocated to the intervention (n = 32) or the control group (n = 28) and included in the analysis. The majority of participants had knee OA (68%), and 12% had hip and knee OA. The dropout rate was n = 11 (18%). No adverse events were reported. Usability was rated as acceptable (mean System Usability Scale = 71.3/100) with a wide range (32.5 to 100). Statistically significant between-group differences were found only for pain (mean difference 8.52 (95% CI 1.01 to 16.04), p = 0.027).

Conclusions: Join2Move demonstrated acceptable usability. The preliminary results of the pilot trial indicate the potential of a stand-alone app for the treatment of patients with hip or knee OA. However, the acceptable usability of Join2Move limits its recommendation for everyone. There appears to be room for improvement in app usability and in identifying patients for whom the app is suitable and the right time to use a stand-alone app.