Abstract

Background: Lower back pain (LBP) is the leading cause of disability worldwide. Despite current recommendations for treatment including physical therapy, patients with LBP have very high non-adherence rates to physical therapy programs. Virtual reality (VR) systems show promise for improving patient adherence and treatment outcomes by providing engaging environments that distract patients from their pain and physical limitations. The Verity’s EnGauge XR ™ is a novel immersive VR system designed specifically for chronic pain management rehabilitation programs. However, the usability of this system for patients with chronic LBP is not yet known.
Methods: Fifteen participants (5 female; mean (SD) age = 45.1 (8.4) years) with chronic LBP were included in this study. Participants incorporated the EnGauge XR ™ range of motion games into their rehabilitation program over two sessions. They completed the suitability evaluation questionnaire after each session, which provides a global score (/65) of perceived usability for VR systems. Participants were asked about any discomfort they felt during the game and scores of pain on a scale from 0-10 were also recorded before and after one session.
Results: Across both sessions, participants rated the system as highly suitable for their rehabilitation needs (Mean (SD) = 58.17 (3.3)). Task difficulty (n=2) and headset weight (n=1) were reported as reasons for discomfort. Pain scores did not significantly differ between pre- and post-VR game use (p=0.17).
Conclusion: Verity’s EnGauge XR ™ system is highly suitable for incorporation into rehabilitation programs for chronic LBP. Pain did not change over the course of one session and consideration is needed for patients who may need more individualised adjustments to the tasks and system set up.

Background

Lower back pain (LBP) is the leading cause of disability worldwide affecting an estimated 619 million people1. This results in a staggering societal and economic burden with an annual cost of > $134 billion in the US alone2. The World Health Organisation (WHO) currently only recommends the use of cognitive behavioural therapy and physical therapy as well as lifestyle changes (increased physical activity, healthy diet, and better sleep habits) to treat chronic pain3. However, despite these interventions ~55% of patients remain refractory to treatment4. Integrating immersive virtual reality (VR) into these programs is one approach that has demonstrated the potential to improve treatment outcomes5-10. In this study, we introduce a novel VR platform for chronic pain management with the aim of evaluating the usability of the system for chronic LBP patients.

Due to the many contributing factors to chronic LBP, it is imperative to treat both the physical symptoms and psychological stressors that may both underlie and manifest as a result of long-term pain. Thus, the primary treatments for chronic LBP are physical therapy rehabilitation and psychological therapy11. Physical therapy programs have the potential to improve disability12, reduce pain, increase range of motion (ROM), and improve independence13 in patients with LBP. Similarly, cognitive behavioural therapy targeting stress reduction, perceptual reframing and fear avoidance may provide additional benefits for alleviating pain14. However, a high proportion of patients do not reach remission or may not respond at all to these treatments4.
Virtual reality may provide added benefits to these interventions due to: 1) increased distraction from the patient’s pain while performing exercises; 2) reduced inhibition of ROM when visual constraints are removed; and 3) greater engagement in the rehabilitation program. When focusing on a task requiring greater attentional demand, people report feeling greater reductions in pain compared to tasks requiring less attentional resources15. By providing a virtual world that removes the patient from their usual environment, VR may aid in distracting the patient from their pain while engaging with the games16,17. Further, the addition of VR has been shown to increase ROM during pain management rehabilitation programs6,7. This may largely be due to their inability to see the location of their limbs within the real world. Removing the visual frame of reference may lead to more free movement that is guided by their actual capabilities as opposed to those constrained by their perceptions of what is possible.
Finally, patients with chronic LBP have very high non-adherence rates to physical therapy programs18, which may greatly contribute to the high percentage of patients who are not responsive to treatment. Virtual reality programs that are more engaging may therefore lead to greater clinical results by increasing overall adherence to treatment19. This is further supported by the notion that immersive VR systems may be more beneficial for pain management than non-immersive VR20.
Taking a holistic approach to pain management and physical rehabilitation, Verity’s EnGauge XR ™ is an immersive VR system that incorporates physical therapy gaming, pain education training, and guided meditation. Physical therapists can adjust the game parameters to cater to the patient’s individual capabilities. Real-time metrics of range of motion and stress parameters allows the patient and therapist to monitor progress and adapt the rehabilitation program accordingly. However, the usability of this system for patients with chronic LBP is not yet known. The primary aim of this study was to determine the usability of the EnGaugeXR ™ prototype for patients with chronic LBP. The secondary aim was to evaluate whether single use of the VerityXR EnGauge system would result in changes in pain.

Methods

Participants
Fifteen participants (5 female) with a mean (SD) age of 45.1 (8.4) years were included in this study. They were recruited from the Premier Pain & Spine clinic in Downers Grove, Illinois. Ethical review and study approval was obtained from Integreview (now Advarra Inc.)
Participants were included in the study if they: 1) were aged 18-70 years; 2) had an existing diagnosis of chronic non-radiating lower back pain lasting > 6 months; 3) could read, write, and speak English with acceptable visual and auditory acuity; and 4) could provide informed consent. They were excluded if they: 1) had visual field deficits that would impact their ability to accurately interpret the VR game; 2) had significant balance difficulties or predominant leg pain symptoms; 3) had a neurological disorder, dementia or cognitive impairment; 4) were morbidly obese; or 5) were pregnant.

Virtual Reality Platform and Procedure

Participants attended two sessions lasting 15-30 minutes with the EnGauge XR ™ prototype system. They continued their usual care in addition to these sessions.
Verity’s EnGauge XR ™ is an immersive VR system integrated with the HTC Vive headset. The system incorporates physical therapy gaming, pain education training, and guided meditation. Physical therapists can adjust the game parameters to cater to the patient’s individual capabilities. Real-time metrics of ROM and stress parameters allows the patient and therapist to monitor progress and adapt the rehabilitation program accordingly.

For the purposes of this study, the participants engaged in ROM rehabilitation-based games, such as bending and squatting, within an interactive virtual environment. The exercises and target ROM were adjusted by the clinician (AP) based on the individual needs of the participant. Four wearable HTC Vive trackers were attached to the participant’s midback, lower back and on the lateral aspects of both knees to allow measurements of ROM within the context of the game. Participants complete the ROM exercises to earn ammunition to use in a target shooting game between exercise sets. To maximise feedback on the usability of the EnGauge XR ™ system, the participants were asked to start the game and self-navigate through the game.

Primary Outcome – Usability

The primary outcome of this study was the usability of the EnGauge XR ™ system. After each VR session, the participants were asked to complete the Suitability Evaluation Questionnaire (SEQ) for VR systems21. The SEQ is composed of a series of 13 five-point likert scale questions from 1= not at all, to 5= very much, that cover perceived enjoyment, ease of use, appropriateness of use, the immersiveness of the system, and any discomfort from the system. The total score ranges from 13 (poor suitability) to 65 (excellent suitability) with negative questions reversed in the scoring, i.e. a rating of 5 on discomfort would be scored as 1 in the overall suitability score.

In addition, participants were asked whether they experienced any discomfort during the game and if there was anything they would change about the game.

Secondary Outcomes

Pain scores on a scale from 0 being no pain to 10 being worst pain imaginable, were recorded before and after the second session.
Statistical Analysis
The mean and standard deviation scores for the overall suitability (/65) as well as for each component of the SEQ (/5) were calculated across sessions. A Wilcoxon signed-rank test was used to determine whether there were any significant differences in pain scores pre- versus post-VR session from session 2. Common suggestions for game changes were reviewed for additional feedback.
Results
All fifteen participants (five females) with a mean (SD) age of 45.1 (8.4) years completed both EnGauge XR ™ sessions. Two participants did not complete pain scores for the second session. All participant characteristics are detailed in Table 1.

Overall, Verity’s EnGauge XR ™ system was rated as highly suitable with a mean (SD) of 58.17 (3.3) across both sessions (session 1 = 57.53 (3.1); session 2 = 58.80 (3.4)). Mean scores for the individual questions can be seen in table 2. There was no significant difference in pain scores after completing a single session of the VR session (p=0.17; see table 2).

In addition, to the outcomes of the SEQ questionnaire detailed in Table 2, participants were also asked whether they felt any discomfort during the game and, if so, why. Over both sessions, four participants indicated they experienced discomfort during the VR sessions (1= feeling a little disoriented initially which resolved by session 2; 1 = tasks hard on their back and knees; 1 = headset was heavy; and 1 = pain when bending forward in one of the sessions).

When asked if there was anything the participant would change about the game, there were four key themes. Firstly, participants wanted more clarification on how to perform the exercises in the game and how to navigate the VR environment, although several noted they did pick it up quickly as the session continued.

Two participants commented on the potential to include some form of reward system within the game e.g. scoring points for every target hit, and two participants requested more moving targets be added to the game. Finally, multiple participants commented on the desire to continue using the game for longer.

Other individual comments included the need for a warmup shooting session, the need to make the game a little more challenging, and options for what audio is used in the game.

Discussion

Verity’s EnGauge XR ™ immersive VR system is designed to enhance pain management and rehabilitation. This study evaluated the usability of the physical therapy gaming component of the EnGauge XR ™ system for patients with chronic LBP. Across both sessions, participants rated the system as highly suitable for their rehabilitation needs and pain scores did not significantly differ between pre- and post-VR game use. Notably, participants rated the system highly for being helpful for their rehabilitation (92%).

On average, the VR system was rated very highly for enjoyment (97%), immersiveness (96%), and realness of the environment (84%). These are key components thought to underlie the potential benefits of VR for chronic pain management. By engaging patients with enjoyable rehabilitation, they may be more likely to adhere to the treatment and reduce kinesiophobia. This is supported by their feedback that multiple participants requested the games to be longer. Further, the level of immersion of the VR system is thought to contribute
to greater outcomes by distracting the patient from their pain and physical limitations16,17.

While reassuring that the participants felt the VR system was immersive, we did not assess the impact of the game on range of motion. Further, no change in pain score was identified pre- and post-VR use from a single session. Thus, it is not possible to elaborate on this hypothesis within this study.

On average, the level of discomfort reported was rated at 25%. Very low ratings were provided for dizziness or nausea (2%), eye discomfort (6%), and feeling confused or disoriented (3%). The reasons for discomfort included the tasks being hard on their areas of pain, and the headset being heavy. This may have contributed to a lack of perceived pain relief during the VR session as well.

Therefore, while most participants did not report any discomfort while using the system, there is a need to further individualise the programs for patients who may find the tasks more challenging and require a more gradual increase in difficulty.

One participant also found the headset to be heavy. Identifying alternative non-immersive or lighter headset options may be necessary for patients who are unable to carry the additional weight of the HTC Vive Pro headset during the exercises. However, further research is needed to determine whether these options would be as beneficial for pain management rehabilitation.

When asked what changes they may like to see in the game, some participants commented on the need for more detailed instructions and the inclusion of a reward system. This emphasises the importance of adequate warm up and training of the system, especially for patients without prior experience of using VR. The request for a reward system is of particular interest as this has been suggested to contribute to increasing adherence19.

Patients who feel they are improving may be more motivated to continue treatment. However, it is important that rewards are finely tuned to encourage correct form and execution of the tasks to maintain safety and reduce risk of overexertion22. How the reward system is incorporated into the system should be considered carefully.
It is important to note that while the primary aim of this study was to evaluate the usability of Verity’s EnGauge XR ™ system, this study is limited in its interpretations of the system over a longer period of rehabilitation.

Further research is needed to evaluate the benefits of the system for pain relief and improvements in range of motion. The results are also not generalisable to patients with conditions other than chronic LBP or for use of the system outside of a physical therapy clinic setting.

Conclusion

Verity’s EnGauge XR ™ system is highly suitable for incorporation into rehabilitation programs for chronic LBP. Specifically, patients believe this system will be helpful for their rehabilitation and find it enjoyable. Pain did not change over the course of one session and consideration is needed for patients who may need more individualised adjustments to the tasks, and greater explanation of system set up.

Conflict of interest

This study was funded by VerityXR of which, AP is CEO and co-founder.

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