Smartphone-Based Video Analysis for Guiding Shoulder Therapeutic Exercises: Concurrent Validity for Movement Quality Control

Abstract

Neuromuscular re-education through therapeutic exercise has a determinant role in chronic shoulder pain rehabilitation. Smartphones are an interesting strategy to extend the rehabilitation to a home-based scenario as it can increase the attraction and involvement of users by providing feedback. Objective: To analyze the concurrent validity of a smartphone’s application based on 2D video analysis against the gold-standard 3D optoelectronic system for assessing movement quality during upper limb therapeutic exercises. Methods: Fifteen young adults were evaluated while executing two different shoulder exercises with a smartphone’s 2D video and a 3D optoelectronic system simultaneously in two conditions: (1) with the supervision and instructions of a physiotherapist (guided exercise), and (2) without the feedback of the physiotherapist (non-guided exercise). The data obtained during the guided and non-guided exercises were compared to calculate the movement quality index based on the approximation of the non-guided exercise to the guided exercise for the head, trunk, and shoulder’s range of movement. The agreement of the movement quality index assessed with the smartphone application and the optoelectronic system was carried out through Bland–Altman analysis. Results: The Bland–Altman analysis indicates the range of agreement and bias tendency. This tendency demonstrates that the percentage of difference between the two methods increases as the movement quality index decreases. Conclusions: There is agreement between the movement quality evaluated by a gold-standard method and the developed application, although the proposed method appears to have less sensitivity for evaluating movements with lower quality index.