Objective: To analyze the concurrent validity and reliability of an iPhone application for assessing range of motion (ROM) and joint position sense (JPS) in ankle and knee joints.
Design: Cross-sectional study.
Setting: Sport laboratory.
Participants: Twenty healthy and physically active volunteers.
Interventions: All participants performed a ROM and a JPS test in ankle and knee joints, which were simultaneously evaluated with photo-analysis and the iPhone application.
Main outcomes measures: A total of 80 angles were obtained with the iPhone app and the photo-analysis and compared for concurrent validity. Reliability was evaluated through re-scoring of images with the iPhone app by two different testers.
Results: Very high correlation was observed between both methods for ankle and knee ROM and knee JPS (r > 0.90), and high correlation for ankle JPS (r = 0.71-0.90), while Bland-Altman plots showed absolute agreement for all the variables. Inter- and intra-tester reliability was perfect for all the variables (ICC > 0.81), except for the inter-tester reliability of ankle JPS, which was substantial (ICC = 0.61-0.81).
Conclusions: This new iPhone application is valid and reliable for measuring ankle and knee ROM and JPS, although special attention is needed during ankle evaluation to avoid errors.
Keywords: Ankle; Knee; Proprioception; Range of motion.
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