Abstract Background: Upper extremity range of motion (UEROM) deficits are common after mastectomy and breast reconstruction, limiting patient recovery and quality of life. Many breast cancer patients report shoulder pain and reduced arm motion months to years post-surgery, including significant declines in abduction and flexion. However, access to frequent UEROM assessment in clinics is limited by time, equipment, and specialized expertise. A smartphone app could offer an accessible solution for at-home UEROM evaluation. We hypothesized that a smartphone application could detect reductions in shoulder abduction and flexion following breast reconstruction, yielding results comparable to those from wearable inertial measurement units (IMUs). Methods: Thirteen female breast cancer patients (mean age 45.5 years, range 35-54) completed at-home UEROM assessments both before and 6-12 weeks after mastectomy with immediate breast reconstruction. Participants performed the assessments simultaneously using an IMU sensor system (placed on sternum, right/left upper arms, right forearm, left forearm) and an iPhone application (MotionDetect module, CareEvolution, Ann Arbor, MI). The app provided standardized audio and video instructions, ensuring consistent arm positioning and movement. UEROM was defined as the maximum angle of abduction and flexion from the torso, measured both by the IMU and iPhone’s onboard sensors. Pairwise changes in pre- and post-surgery mobility were compared within and across both measuring methods using paired t-tests. Agreement between IMU and iPhone app measures was determined using Pearson correlations. Results: Both IMU and iPhone app measures detected significant declines in the maximum shoulder abduction and flexion following breast reconstruction. 30% of enrolled mastectomy patients exhibited clinically meaningful UEROM limitations exceeding 20 degrees post-surgery, consistent with prior studies. Specifically, the IMU detected significant decreases in abduction (p = 0.007) and flexion (p = 0.007), while the iPhone app detected significant reductions in flexion (p = 0.004) and a trend toward decreased abduction (p = 0.08). The pre-post difference in UEROM between the elevation angles derived by the IMU sensors and the iPhone app were statistically similar (both p 0.15), with strong correlations between the IMUs and iPhone app measures in abduction (r = 0.92) and flexion ranges of motion (r = 0.96). Discussion: This study demonstrates that a smartphone app is able to detect and quantify upper extremity range of motion deficits following breast reconstruction surgery with comparable results to a wearable IMU sensor system. The app consistently identified significant post-operative decreases in shoulder mobility, suggesting it can serve as a convenient, accessible means for remote UEROM monitoring. These app-based assessments are far more scalable for use in clinical trials and practice than sensor-based assessments. The smartphone app’s ease of use may facilitate telehealth-based monitoring, enabling clinicians to intervene earlier and address mobility restrictions, which could potentially improve patient outcomes and quality of life. Citation Format: D. B. Lipps, K. Russell-Bertucci, S. M. Cain, P. L. Myers, A. O. Momoh, D. L. Hertz. Prospective assessment of upper extremity range of motion changes following mastectomy and breast reconstruction using a novel smartphone app abstract. In: Proceedings of the San Antonio Breast Cancer Symposium 2025; 2025 Dec 9-12; San Antonio, TX. Philadelphia (PA): AACR; Clin Cancer Res 2026;32(4 Suppl):Abstract nr PS1-04-02.
Lipps et al. (Tue,) studied this question.