## 2 Materials and Methods
### Plantar Pressure and Gait Analysis
#### 2.5.1 Baropodometric Platform  
The baropodometer is a platform used to analyze plantar pressure distribution in both a static and dynamic position. A software elaborate data from static and weight-bearing plantar pressure distribution during gait (dynamic baropodometry). For this study, the flexible baropodometric platform model FLEX EPS/R2 by Letsense(r) (Letsense group, Bologna, Italy) was used [30]. This platform consists of 2304 resistive sensors, and the platform's active surface measures 48 \(\times\) 48 cm\({}^{2}\) and is formed by a conductive polymer layer, where sensors are arranged in matrix form. The results are displayed and analyzed using Biomech Studio 2018(r) software for Windows. In the static examination, the patient climbed on the platform, looked at a fixed point ahead and slightly spread the feet. The feet were placed parallel to each other, spaced about should-width apart. The patient emptied their pockets from any objects that they had and/or any accessories they had on the arms/wrists before stepping on the platform to not impair weight distribution. The patient maintained an upright posture for 30 s (the duration varies depending on the type of patient and data needed to be analyzed). In this orthostatic measurement, the following parameters were evaluated:  
* Total anteroposterior load distribution [%] (Figure 2): indicates the load distribution between the hindfoot and forefoot of both feet. Normal reference values: 40-45% in forefoot; 55-60% in hindfoot. Figure 1: Ankle Lunge Test (ALT). The patient positions their foot perpendicular to the wall and brings their knee towards it. The foot is then gradually moved away from the wall until the maximum ankle dorsiflexion is achieved without lifting the heel. The distance between the foot and the wall, reported in cm, and the angle of the tibial shaft from the vertical, reported in degrees (\({}^{\circ}\)), was then measured. * Mean pressure [kPa] (Figure 2): indicates the average plantar pressure recorded in each foot. This parameter is improved with the reduction in the difference between the mean pressure values of the operated foot and the non-operated foot. The reference scale considered ranges from 0 to 500 kPa. * Peak pressure [position, kPa]: indicates the point on the foot where the maximum pressure value is recorded, with the maximum value associated. * Ellipse area of the body's barycenter [mm\({}^{2}\)] (Figure 2): indicates the movement of the barycenter and center of pressure (C.O.P) of the two feet. The ellipse represents 90% of it. * Ellipse area of the foot's barycenter [mm\({}^{2}\)] (Figure 2): indicates the movement of the barycenter and center of pressure (C.O.P) of the foot. The ellipse contains 90% of it. * C.O.P. distance [mm] (Figure 2): indicates the average distance of the C.O.P. trajectory from the central point of the trajectory itself. The reduction of the elliptical surface of the body's barycenter, elliptical surface of the foot's barycenter and C.O.P. distance indicates a lower movement of the center of pressure and, therefore, a greater stability of the barycenter of the patient examined. In the dynamic examination, the patient walked forward and backward so that their third step was performed on the platform. Every foot was measured 6 times. Each parameter was recorded as a mean value using the aforementioned software. The main parameters reported by the software were as follows:  
* Mean pressure [kPa]: indicates the average plantar pressure recorded in each foot. This parameter is improved with the reduction in the difference among the mean pressure values between the operated and non-operated foot. The reference scale considered ranges from 0 to 500 kPa. * Peak pressure during gait [position, kPa]: indicates the point of the foot where the maximum pressure value is recorded at each step stage (contact phase, intermediate support phase, propulsion phase), with maximum associated value. * Maximum load points curve: connects all the maximum load points at every moment of the step, in both feet.