## 4 Discussion
### Effects of Textured Insoles on Each Group  
Although there were no interactions, paired \(t\)-tests were conducted to find out whether the textured insoles improved the balance of each group. In knee OA group, there were significant improvements in conditions 5 and 6, Comp, VEST, and PMAN when wearing the textured insoles. In the healthy knee control group, there were statistically significant improvements in condition 6, Comp, VIS, and PMAN when wearing the textured insoles. Condition 6, in which the visual and somatosensory information was altered, was the only condition in which both groups affected by textured insoles. This finding is consistent with previous research by [PERSON] et al. [34], who demonstrated that textured insoles improved balance even in a more challenging situation with conflicting visual and somatosensory inputs. It is important to note, however, that [PERSON] and collegues' study [34] did not attempt to embed textured insoles into shoes, but rather investigated the effects of a textured standing surface in older adults. Considering the improvement of VEST in the knee OA group, it seems to be due to an improvement of condition 5, because the improvedcondition 5 is thought to be due to a higher reliance on somatosensory information by the use of textured insole, not by functional improvement of the vestibular system. Significant improvements in the PMAN in both groups could be of interest. All participants who wore the textured insole were able to better maintain their balance in inaccurate somatosensory situations, leading to a higher reliance on somatosensory orientation, which would not have been possible without the textured insole. This could be attributed to increased cutaneous afferent receptor activity while wearing the textured insole due to hyperesthesia of the plantar surfaces of the feet. More specifically, the physiological mechanisms by which textured insole can cause changes in balance suggest that textured insole provide enough stimulation to change the rate of discharge from mechanoreceptors or the firing patterns of sensory afferents located in the skin of the plantar surface [63]. This effect would result in enhanced neural feedback from the cutaneous receptors to the central nervous system, potentially contributing to improved balance. The textured insole enhanced balance in the knee OA group, most likely due to the increase in somatosensory input from the plantar surfaces. These findings add to current understanding of the research by complementing the existing data. For example, our findings are consistent with those of [PERSON] et al. [20], who investigated the use of vibration insole and found that improved somatosensory feedback can improve balance while standing. Providing vibrational stimulation to the plantar surface of the feet has been proposed as a potential mechanism through which footwear intervention could improve balance [19; 21; 22] by altering sensorimotor function. The distinction between previous and current research was in the characteristics of the foot stimulation. The plantar surface remained in contact with the indentations of the textured insole in this study. When cutaneous afferents continually respond to prolonged indentations, they are classified as slow adapting mechanoreceptors [25]. In comparison, vibratory interventions allow for the manipulation of the stimulation's frequency, intensity, phase, and duration. These interventions may have an effect on fast-adapting mechanoreceptors that respond to stimulation with bursts [64]. As the textured insole used in this study did not deliver electrical stimulation, they did not act on the same concept. Furthermore, such vibration devices may be costly and difficult to employ as an effective intervention to improve balance in daily life. Textured insole may be a viable alternative and a cost-effective technique to improve balance.