## 4 Discussion
### Comparison between the Knee OA Group and Health Knee Group  
The findings of the balance performances with smooth insoles comparing the individuals with knee OA and the healthy knee controls showed that conditions 3, 5, and 6, Comp, VEST, and PMAN were significantly higher for healthy knee controls than individuals with knee OA. Lower EQ values in the knee OA group indicated greater forward-backward displacements of the center of gravity. The Comp score indicated both groups' overall performance, and a lower score indicates that the OA group was unable to maintain balance and a stable position during the SOT test procedure, in comparison to the healthy knee group. In conditions 5 and 6, when participants were required to compensate for visual deprivation and inaccurate somatosensory information by increasing their reliance on vestibular information, there was an increase in the number of falls and a decrease in equilibrium scores. Furthermore, individuals with knee OA also had decreased VEST and PMAN ratios, according to sensory analysis data. In comparison to healthy knee controls, these findings suggest a reduced usage of vestibular and somatosensory afferents. The VEST ratio revealed the usefulness of the signal from a vestibular system to maintain balance, traditionally indicating the quality of the vestibular afferent [42]. All individuals had to compensate for the visual loss and inaccurate somatosensory information in conditions 5 and 6 by increasing their use of vestibular information [44]. A previous study found that poor balance function was associated with a lower reliance on vestibular afferents [36]. According to [PERSON] and colleagues [45], people with vestibular system deficits rely heavily on visual cues, and they lose balance if the visual information is removed by closing their eyes [46]. When visual input was removed and somatosensory inputs were altered (condition 5), EQ scores decreased significantly. However, the  
Figure 7: Results of latencies. * Statistically significant mean difference (\(p<0.05\)). increased number of falls and decreased equilibrium scores observed in conditions where visual and somatosensory information was distorted or removed could also indicate a sensorimotor processing deficit rather than vestibular system dysfunction [47]. To maintain balance, the central nervous system (CNS) must be able to select appropriate sensory information while ignoring insufficient sensory information. The CNS then compares them to an internal model before sending motor commands to the muscles [48]. However, based on the sensory information available, this central processing may provide inappropriate responses, resulting in a loss of balance [49]. In this study, the function of the vestibular system or central processing in persons with knee OA is unknown, and whether these balance deficiencies represent decreased functionality in individuals with knee OA is also unknown. However, various possible processes could explain the OA group's balance deficit, although this cross-sectional investigation does not allow these to be confirmed. Individuals with knee OA frequently exhibit several factors that negatively affect their balance, including muscle weakness [50; 51; 52], impaired somatosensory function [11; 51; 53; 54], and joint contract [55], as well as significant decline of mechanoreceptors compared to age-matched healthy peers [9]. Additionally, individuals with knee OA had a slower neuromuscular response latency to balance perturbations, indicating a reduced ability to begin in recovering balance rapidly after an unexpected disturbance. The previous research has demonstrated that the triggering of the automatic balance corrections is dependent on hip and trunk proprioceptive inputs, and knee inputs provide a supplementary trigger signal that allows the generation of the very early part of the triceps surae responses [42; 56].