## 4 Discussion  
The results of this study were obtained using a preliminary inference analysis. During DRF treatment in the acute phase, the wrist joint must be immobilized; however, somatosensory inactivity must be overcome. Therefore, possible solutions need to be explored. This study shows that Ghost can be used for treatment in this phase. Statistical analyses revealed that both interventions resulted in a significant improvement in the RoM over time in patients with DRF. In addition, the arc of wrist motion was larger in the Ghost group than the control group. Recovery of RoM after treatment with our new therapeutic technique that used somatic and visual stimuli differed depending on age and BMI. This study also provided data on wrist joint RoM recovery following interventions in the acute phase in patients with DRF. Based on these results, our next study will be on the large-scale implementation and verification of the effects of the Ghost device and the extent of RoM recovery that can be expected according to the patient's age and BMI. The BMI of patients with DRF affected RoM recovery, and younger patients recovered more than older patients. Differences in the arc of motion between the Ghost and control groups were estimated to be less than 10\({}^{\circ}\), and these results did not indicate superiority of the new device. The 95% confidence interval of the minimum detectable difference (MDD\({}_{95}\)) has been reported to determine a patient's recovery [24]. The MDD\({}_{95}\) of the arc of motion of wrist flexion-extension measured using a manual goniometer has been reported to be 18\({}^{\circ}\)[24]. Previous studies of interventions using vibratory stimuli [10] and the evaluation in DRF patients did not investigate changes in RoM during the acute phase [33]. [PERSON] et al. reported that the recovery of strength of muscles involved in forearm pronosupination in patients with DRF is approximately 40% at 6 weeks after surgery, and a period of approximately 18 months is required for complete recovery [34]. Our actual data was from a small sample, but it was of the RoM in the acute phase. Intervening in the joint fixation period and improving the RoM even slightly may significantly support the recovery of DRF patients. A person's tactile threshold increases with age [35; 36]. [PERSON] et al. reported that patients in their 60s were more likely to make mistakes in a VR environment and were slower to move than those in their 20s [26]. The mean age of the patients in the Ghost and control groups was 76 and 69 years, respectively. Previous studies have suggested that vibration and VR were more effective therapies in younger patients than in older patients such as those included in this study. Future studies should examine whether young patients adapt well to a VR environment and experience strong sensory stimulation using the Ghost system. Underweight Asian patients with femoral fracture have been reported to have poor ADL performance and lower rates of discharge to home than overweight or obese patients [37]. In contrast, [PERSON] et al. reported that DRF severity and obesity were not related to recovery [38]. [PERSON] et al. reported differences in functional recovery according to BMI [27]. Obesity is associated with the impaired T-cell regulation, characterized by an increased number of cells, and dysregulation of vitamin D metabolism [39; 40]. Even in our small data, BMI was associated with DRF recovery, and we therefore recommend that BMI and nutritional status be considered when validating new therapies. Alleviated pain may contribute to improved RoM [3; 10]; therefore, a vibratory stimulus was provided to all patients during this study. We did not report on the patients' pain intensity. The quantity of deformed sensory receptors is increased in soft tissues around joints in patients with fractures or joint degeneration [41]. Because of the increased quantity of deformed sensory receptors and increased concentration of pain-transmitting substances, patients perceive pain for a long time.