## 7 Discussion
\begin{table}
\begin{tabular}{c c c c} \hline \hline  & **Right Foot** & **Right Foot** & \(p\)**-Values** \\  & **Post-Injury (N = 11)** & **Healthy (N = 11)** & \(p\)**-Values** \\ \hline Monopodalic Ellipse Area (mm\({}^{2}\)) & 105.91 \(\pm\) 67.87 & 128.25 \(\pm\) 93.83 & \(>\)0.05 \\ Monopodalic CoP Speed (mm/s) & 13.84 \(\pm\) 3.24 & 14.23 \(\pm\) 5.05 & \(>\)0.05 \\ Arabesque Ellipse Area (mm\({}^{2}\)) & 274.40 \(\pm\) 255.50 & 165.17 \(\pm\) 127.18 & \(>\)0.05 \\ Arabesque CoP Speed (mm/s) & 21.84 \(\pm\) 8.46 & 19.32 \(\pm\) 4.38 & \(>\)0.05 \\ Passé Ellipse Area (mm\({}^{2}\)) & 222.49 \(\pm\) 130.06 & 148.15 \(\pm\) 82.43 & \(>\)0.05 \\ Passé CoP Speed (mm/s) & 22.22 \(\pm\) 4.98 & 20.75 \(\pm\) 6.92 & \(>\)0.05 \\ \hline \hline \end{tabular} Data are reported as Mean \(\pm\) SD. Abbreviation: CoP, Centre of Pressure.  
\end{table} 
Table 5: Comparison between right feet of pathological and healthy subjects for stabilometric parameters acquired with open eyes. important bias [37]. In fact, using the contralateral healthy feet as a control, we were able to eliminate biases caused by potential differences in skills, body types, and other physical characteristics between athletes. Recently, a few studies pointed out that a crossover effect of injuries can exist, especially tendinitis, from one side to the other [38,39]. While it is not clear the mechanism of action of this crossover effect (e.g., central nervous system or anticipatory postural adjustments [40]), it still could be a possible confounder of our results as the pathological and healthy side could be similar because of it. Our study arrived to a different conclusion than a similar 2011 study [25]; however, we focused on a more selective group of subjects who had only grade II ankle injury. We supposed that patients with more severe ankle grains could have long-term impairment in postural control. One strength of our study was the use of stabilometry in a new way, comparing ballet-specific static positions for determining ankle injury effects. We found just two studies that examined ballet-specific positions; one examined the single-leg retire position [37] and the other the passe en demi-pointe position [24]. However, neither of the studies focused on post-injury athletes. Another strength of the study was the comparison between healthy and injured feet in the same athletes that eliminate the role of possible differences in skills between different subjects, allowing us to better study the role of the previous ankle injury. Furthermore, we recruited the subjects in six different ballet schools. Different centers have different training strategies, so the results obtained are probably not linked to a peculiar type of training but to the natural history of grade II ankle injuries. A limitation of our study is the small number of subjects involved; however, we enrolled 22 patients (11 for each group) as resulted with the sample size calculation. Our inclusion criteria were very strict to guarantee the internal validity of our study, and despite screening six different centers, we were able to find 11 patients meeting the required inclusion criteria for the pathological subjects group. Furthermore, because of our study design, we cannot exclude an important role of specific rehabilitation protocol in speeding up the recovery process, as we tested our patients long after their injury. In the future, it could be important to study in a similar fashion different grades of ankle injuries, classified using imaging support, as well as different types of ankle injuries, such as inversion andeversion. Moreover, it could be interesting to evaluate the parameters used in our study in releve, another ballet-specific position. One more possible future study could investigate the role of treatment (e.g., immobilization (functional or rigid) vs. no immobilization) and rehabilitation in the time to return to optimal performance as well as potential long-term effects in ankle injuries of higher clinical grading.