JMIR Publications

ABSTRACT

Background:

Frozen shoulder causes prolonged pain and restricted range of motion that impair daily function. Home exercise is an indispensable part of self-management, but adherence is often suboptimal under traditional printed or verbal instruction because of the lack of objective monitoring and individualized progression. Existing rehabilitation applications offer sensor-based assessment and feedback but generally lack an adaptive mechanism that tailors the exercise prescription to a patient's dynamically changing clinical status.

Objective:

This study aimed to develop a personalized, pain-stratified telerehabilitation application for patients with frozen shoulder; to evaluate its usability, feasibility, and safety as an add-on to usual care; and to obtain exploratory clinical signals and design parameters to inform a future definitive trial.

Methods:

An Android application integrating smartphone sensor-based range-of-motion self-assessment, pain-based exercise stratification, usage records, and exercise reminders was developed. In an assessor-blinded pilot randomized controlled trial, 10 patients with frozen shoulder were randomly allocated to an app group (n=5) or a Handout group (n=5), and both underwent a 4-week home exercise intervention with identical content. Outcomes included system usability (System Usability Scale [SUS]), feasibility (retention and exercise adherence), pain and function (Shoulder Pain and Disability Index [SPADI]), and range of motion (measured by goniometer). Given the pilot design, continuous variables were analyzed nonparametrically and interpreted strictly as descriptive clinical trends without inferential hypothesis testing.

Results:

All 10 participants completed the trial (attrition rate 0%). The mean SUS score in the app group was 87.5 (SD 5.86), corresponding to an "excellent" usability rating. Over the 4 weeks, the App group logged higher objective exercise adherence (mean 18.0, SD 5.0 days; 64.3%) than the Handout group's self-reported adherence (mean 11.8, SD 3.9 days; 42.1%). Both groups improved in SPADI scores and range of motion. Notably, all participants in the App group achieved a descriptive within-group improvement in the clinically challenging shoulder external rotation, whereas the Handout group showed smaller marginal gains; however, between-group comparisons across all parameters were interpreted descriptively without significance testing due to the sample size. On the other clinical outcomes, the Handout group showed numerically comparable or larger improvements.

Conclusions:

This pilot study shows that a pain-stratified, personalized telerehabilitation application is highly usable and feasible as an add-on mHealth intervention for patients with frozen shoulder, and that it provides objective home monitoring of exercise adherence that traditional handouts cannot. Because the trial was neither designed nor powered to test clinical efficacy, the exploratory clinical data were interpreted descriptively and should not be read as evidence of superiority over an educational handout; rather, they yield variance estimates and design lessons—including the need for stratified allocation and a common objective adherence measure—to inform an adequately powered definitive trial. Clinical Trial: This trial was not registered in a public registry. As a small pilot and feasibility study whose primary outcomes were usability and feasibility rather than clinical efficacy, it falls outside the scope of mandatory prospective trial registration for efficacy trials. Any subsequent adequately powered efficacy trial based on this prototype will be prospectively registered.