The concurrent validity and reliability of virtual reality to measure shoulder flexion and scaption range of motion.

Background: Shoulder pain commonly has a detrimental impact on patient's work and social activities. Although pain is the most common reason for seeking care, a reduction in shoulder range of motion (ROM) is another common impairment. ROM assessment is used as an evaluation tool and multiple methods are available to measure shoulder ROM. Virtual reality (VR) has been introduced into shoulder rehabilitation, mostly when exercise and ROM measurement is indicated. This study evaluated the concurrent validity and system reliability of active ROM measurements of VR for people with and without shoulder pain.

Methods: Forty volunteers participated in this study. Virtual goniometry was used to assess active shoulder ROM. Participants performed flexion and scaption to six predetermined angles. Measurements from the VR goniometer and smartphone inclinometers were recorded simultaneously. To assess reliability, two identical test sequences were performed.

Results: The concurrent validity ICCs were 0.93 for shoulder flexion and 0.94 for shoulder scaption. The VR goniometer application on average systematically overestimated the ROM compared to the smartphone inclinometer. The mean difference between goniometer values was -11.3 degrees for flexion and -10.9 for scaption. The system reliability was excellent with an overall ICC of 0.99 for the flexion movements and 0.99 for the scaption movements.

Conclusion: Although the VR system demonstrated excellent reliability, and high ICC's for concurrent validity, the large range between the lower and upper 95% CI limits suggests it lacks measurement precision. This suggests VR, as used in this study, should not be used interchangeably with other measurement tools. CONTRIBUTION OF THE PAPER.