## 2 Methods
### Experimental Design and Set-Up  
HV angle was measured with a finger goniometer in a weight-bearing position with bare feet. To measure this angle, one arm of the goniometer was placed on the medial part of the proximal phalanx and the other arm on the first metatarsal bone of the big toe. This method has been evaluated and accepted previously [16; 17]. Based on the study by [PERSON] et al. [18], feet with an HV angle lower than 20 degrees were assigned to the Without-HV group and those with an HV angle equal or higher than 20 degrees were assigned to the With-HV group. US images were taken by the customized machine WBPUID that allows taking images in a weight-bearing position [9; 19] using an US diagnostic device (Noblus, Hitachi Aloka Medical, Tokyo, Japan) at B-mode US with a frequency of 9.0 MHz [9]. WBPUID was previously tested to evaluate the structure of the transverse arch in the coronal plane, and its images were in agreement with computed tomography ultrasonography [14]. The device is rectangular in shape and has a built-in US probe on one side and a scale on the other side. The probe was installed from inside the box with an opening on the surface where patients can position their feet. A gel pad was cut to the same size of the probe opening and placed above it. US gel was also used on top of the gel pad before each test to ensure clearer visibility. On the other side, the scale allowed the control of weight distribution on both legs. Images were taken in three positions: (1) sitting, (2) quiet standing, and (3) 90% W.S. on the tested foot. The measurements were taken by two therapists. One therapist was in charge of positioning the feet on the US probe opening, monitoring, and taking the projected US images. The other therapist was in charge of giving the instructions in native language and monitoring the weight scale. First, body weight was measured, and calculations were done. Next, the therapist placed the tested foot on the US probe opening and confirmed the configuration of the lowest points of the epiphysis of the medial sesamoid bone (MS), the lateral sesamoid bone (LS), the second metatarsal head bone (2 MTH), and the fifth metatarsal head bone (SMTH) [9]. For the 90% W.S. position (Figure 2), 90% of body weight was transferred onto the tested foot and shifted forward on its forefoot. This position is intended to simulate the terminal stance of gait in the static position, relying on the fact that 90% to 110% of body weight is being shifted unilaterally  
\begin{table}
\begin{tabular}{c c c c} \hline \hline  & **Without-HV (n = 260)** & **With-HV (n = 118)** & \(p\)**-Value** \\ \hline HV Angle (\({}^{\circ}\)) & 9.4 \(\pm\) 5.0 & 29.6 \(\pm\) 9.4 & \textless{}0.0001 \({}^{\star}\) \\ Age (years) & 68.9 \(\pm\) 9.3 & 69.6 \(\pm\) 8.7 & 0.454 \\ Height (cm) & 153.7 \(\pm\) 6.0 & 154.7 \(\pm\) 6.0 & 0.146 \\ Weight (kg) & 52.8 \(\pm\) 10.2 & 51.5 \(\pm\) 7.7 & 0.161 \\ \hline \hline \end{tabular} \({}^{\star}\)significant result; (HV Halux Valgus).  
\end{table}
Table 1: Demographic Data of 189 Participants. Results are shown as mean \(\pm\) SD; \(p\) = 0.05.  
in a terminal stance and that the heel is off the ground [10]. In order to prevent the participants from getting injured, we instructed them to shift their weight on the tested foot until the scale under the not-tested foot showed 10% of their body weight, and to sway their bodies forward. In other words, if the individual weighed 50 kg and the right foot was being tested, the instructions were given as: \"Put your weight on your right foot until the scale under your left foot says 5 kg, then move your body forward.\" All participants were able to maintain this posture independently. A similar 90% weight-loading positioning and the WBPUID parameters were previously used and validated by our laboratory members [9; 19].