Virtual embodiment for improving range of motion in patients with movement-related shoulder pain: an experimental study

Abstract

Background: Recent evidence supports the use of immersive virtual reality (VR) as a means of delivering bodily illusions that may have therapeutic potential for the treatment of musculoskeletal conditions. We wanted to investigate whether a single session of an embodiment-based immersive VR training program influences pain-free range of motion in patients with shoulder pain.

Methods: We designed a rehabilitation program based on developing ownership over a virtual body and then "exercising" the upper limb in immersive VR, while the real arm remains static. We then carried out a single-arm pre-post experiment in which 21 patients with movement-related musculoskeletal shoulder pain were exposed to the 15-min VR program and measured their active pain-free range of motion immediately before and afterwards.

Results: We found that shoulder abduction and hand-behind-back movements, but not shoulder flexion, were significantly and clinically improved post-intervention and that the level of improvement correlated with the level of embodiment. Following this one session, at 1-week follow-up the improvements were not maintained.

Conclusions: Virtual embodiment may be a useful therapeutic tool to help improve range of motion in patients with movement-related shoulder pain in the short term, which in turn could expedite rehabilitation and recovery in these conditions.

Keywords: Body functionality; Embodiment; Musculoskeletal; Pain; Rehabilitation; Virtual reality.

Fig. 1

Bodily landmarks used to calculate range of motion. Shoulder (A) abduction, (B) flexion, and (C) hand-behind-back movements

Fig. 2

Experimental setup. A The virtual scene observed by the patients; note the virtual mirrors which enhance avatar-self visual feedback; B patient positioned quietly throughout; note the coin vibrators strapped to the fingers to provide tactile sensations during visuotactile feedback; C therapist demonstrating the movement/exercise to be performed; D pedal used to initiate the movement and confer a sense of agency over the movement

Fig. 3

Active abduction range of motion. Boxplot showing. A shoulder abduction range of motion before and after the immersive VR session and 1 week later; and B individual patient response pre- and post-intervention. **p < 0.01

Fig. 4

Active hand-behind-back movement. A Boxplot showing hand-behind-back range of motion before and after the immersive VR session and 1 week later and B individual response; Tx, thoracic spinal level; Lx, lumbar spinal level x; S, sacral spinal level: SIJ, sacroiliac joint; Sac, sacrum, MB mid-buttock; GF, gluteal fold; GT, greater trochanter. **p < 0.01

Fig. 5

Active flexion range of motion. A Boxplot showing shoulder flexion range of motion before and after the immersive VR session and 1 week later and B individual patient response pre- and post-intervention

Fig. 6

Association between outcomes: A Virtual body ownership vs abduction change. B Virtual body ownership vs hand-behind-back change. C Virtual body ownership vs flexion change. D Virtual body ownership vs baseline disability. E Presence vs baseline disability. F Disability versus flexion change