Comparison of movements in a virtual reality mirror box therapy for treatment of lower limb phantom pain

Many patients experience Phantom Limb Pain (PLP) after an amputation. Traditional Mirror Box Therapy (MBT) has proven efficient for some patients, but the movements in MBT are physically limited, for lower limb amputees. In this work, we investigated how anti-symmetrical mirroring compares to regular mirroring in Virtual Reality (VR) MBT for lower limb amputees, as natural leg movements are anti-symmetrical, like walking, running, and cycling. To motivate the patients, a game was developed that uses cycling and swinging movements. We implemented the required movements into a goal-oriented game where the patient must fly a gyrocopter through goal areas. The experiment was implemented as a within-subject design, where the participants had to try three versions of the game and give preferential feedback. The findings showed that the cycling version was more exhausting than the anti-symmetrical and symmetrical swinging versions. Furthermore, we discovered that the required cycling motions were too difficult and tiresome to do over a longer period of time. On the other hand, we found that it is possible to use anti-symmetrical swinging of legs in VR MBT.