## 3 Results
### Postural Stability and Proprioception Assessment
#### 3.1.2 Single-Stance Test  
The SI and AU values both for OE and CE trials for females and males for the KOA limb are reported in Table 3, and compared with reference values.  
The Stability Index (SI) was found statistically lower with respect to reference values only for females both when considering the average value between the two limbs and also when considering the OA limb and the contralateral limb separately. Correspondently, Autonomy (AU) was significantly lower with respect to reference values both for the average value and for the single limbs.  
In the trial with closed eyes (CE) females showed reduced Stability Index values with respect to the reference data, but only for the trial with singles stance on the contralateral limb (\(p=0.05\)). As a consequence, Visual Gain, that is the difference between the trial with open eyes and closed eyes, was reduced in the female group (Table 4). No difference was found for males for the Stability Index and Autonomy.  
\begin{table}
\begin{tabular}{c c c c c c} \hline \hline  & & **Mean** & **SD** & \(n\) & \(p\)**Value** \\ \hline VG-single & F & 28.0 & 11.1 & 21 & 0.02 \\ average & M & 33.7 & 13.8 & 17 & 0.39 \\ all & 30.5 & 12.5 & 38 & - \\ VG-single & F & 35.2 & 16.0 & 119 \\ reference & M & 34.5 & 15.7 & 117 \\ data 1  & all & n.a. & n.a. & - \\ \hline \hline \end{tabular}
\end{table}
Table 4: Visual Gain.  
\begin{table}
\begin{tabular}{c c c c c c c c c} \hline \hline  & & \multicolumn{3}{c}{**SI**} & \multicolumn{3}{c}{**AU**} & \multirow{2}{*}{\(p\)**Value**} \\ \cline{2-2} \cline{6-9}  & & **Mean** & **SD** & \(n\) & & **Mean** & **SD** & \(n\) \\ \hline Average (KOA limb and contralateral) OE & F & 64.5 & 12.1 & 21 & \(<\)0.0001 & 79.5 & 14.4 & 21 & 0.01 \\  & M & 71.2 & 14.2 & 17 & 0.25 & 85.7 & 14.8 & 17 & 0.40 \\  & all & 67.4 & 13.3 & 38 & - & 82.2 & 14.7 & 38 & - \\  & F & 59.1 & 17.9 & 21 & \(<\)0.0001 & 74.8 & 21.9 & 21 & 0.01 \\ KOA limb OE & M & 69.1 & 19.7 & 17 & 0.21 & 84.5 & 20.6 & 17 & 0.39 \\  & all & 63.5 & 19.1 & 38 & - & 79.1 & 21.6 & 38 & - \\ Centralateral Limb OE & F & 65.8 & 19 & 21 & 0.02 & 79.7 & 21.1 & 21 & 0.06 \\  & M & 73.2 & 16.1 & 17 & 0.37 & 86.8 & 15.3 & 17 & 0.39 \\  & all & 69.1 & 17.9 & 38 & - & 82.8 & 18.8 & 38 & - \\ Reference data OE 2  & F & 74.9 & 20.4 & 119 & & 858 & 20.0 & 119 & \\  & M & 76.6 & 17.5 & 117 & & 89 & 17.4 & 117 & \\  & all & n.a. & n.a. & - & & n.a. & n.a. & - \\ Average (KOA limb and contralateral) CE & F & 36.5 & 9.5 & 21 & 0.06 & 47.7 & 13.2 & 21 & 0.11 \\  & M & 37.4 & 13.8 & 17 & 0.31 & 50.4 & 17.0 & 17 & 0.40 \\  & all & 36.9 & 11.4 & 38 & - & 48.9 & 14.8 & 38 & - \\ KOA limb CE & F & 37.8 & 12.9 & 21 & 0.21 & 48.1 & 15.4 & 21 & 0.16 \\  & M & 35.3 & 13.3 & 17 & 0.16 & 48.5 & 17.2 & 17 & 0.36 \\  & all & 36.6 & 12.9 & 38 & - & 48.3 & 16 & 38 & - \\ Centralateral Limb CE & F & 34.4 & 14.1 & 21 & 0.05 & 46.6 & 19.0 & 21 & 0.14 \\  & M & 39.6 & 16 & 17 & 0.40 & 52.3 & 19.6 & 17 & 0.37 \\  & all & 36.7 & 15 & 38 & - & 49.1 & 19.2 & 38 & - \\ Reference data CE 3  & F & 40 & 14.6 & 119 & & 50.5 & 17.9 & 119 & \\  & M & 41.4 & 15.8 & 117 & & 53.2 & 19.2 & 117 & \\  & all & n.a. & n.a. & & n.a. & - & \\ \hline \hline \end{tabular}
\end{table}
Table 3: Single limb stance test.  
No relationship was found between age, BMI and KSS-C with postural stability and proprioception variables. The average Stability Index at OE was also correlated to KSS-F (Rho 0.456, \(p=0.004\)) and SSPB (Rho = 0.380, \(p=0.019\)), which means that a better KSSF and SPPB score corresponds at higher Stability Index (Table A1).  
The radiological degree of knee OA, as measured by the Kellgren-Lawrence score, was significantly correlated to the Stability Index when standing on the KOA limb with OE (tau = \(-0.277\), \(p=0.039\)) and with average Stability Index with OA (tau = \(-0.313\), \(p=0.020\)), which means that at higher degrees of Kellgren-Lawrence, lower Stability Index was present (Table A2).