# Gait Kinematics Analysis of Flatfoot Adults
## 4 Discussion
They also stated some evidence of increasing FF posture was positively correlated with an increased frontal plane motion of the rearfoot and therefore translated into the navicular bone drop present in FF subjects. As previously noted, we did not find greater ankle adduction or abduction in the FF subjects. Our results do not always match the several studies that have analyzed the static posture of FF subjects that found those correlations between joints kinematics ([PERSON] et al., 2015; [PERSON] et al., 2015; [PERSON] et al., 2015; [PERSON] et al., 2015; [PERSON] et al., 2015). They stated that during the medial longitudinal arch drop, the foot is forced to maintain exaggerated pronation, and through the coupling kinematics between the foot, tibia, and femur, subjects presented an increased internal rotation of the hip. FF subjects only showed a greater knee peak flexion peak (\(p\) < 0.001) during gait. Even so, those subjects showed a lesser knee peak extension (\(p\) < 0.001), abduction (\(p\) < 0.001), and external rotation (\(p\) < 0.001) with significant differences compared to NF participants. However, knee flexion/extension ROM (\(p\) = 0.000) is higher in FF subjects, while the NF group presents a higher abduction/adduction ROM (\(p\) < 0.001). In children aged 11-12 years of age, [PERSON] et al. (2012) found a significant difference between the two groups regarding the adduction/abduction peak value (\(p\) = 0.01), with a greater value for the FF group concerning the condition of the valgus. Additionally, the authors did not find any significant results in the sagittal or transverse plane of the knee. Additionally, FF subjects presented a higher hip peak flexion (\(p\) = 0.002) alongside a higher internal rotation peak (\(p\) < 0.001). However, the NF participants presented higher peak values of hip extension (\(p\) = 0.006) and hip external rotation (\(p\) = 0.012) with significance. Thus, the FF subjects showed a significantly less ROM concerning hip flexion/extension (\(p\) = 0.002) and internal/external rotation (\(p\) = 0.007). Our results are in contrast to those stated by [PERSON] et al. (2012), who related greater hip external rotation peak (\(p\) < 0.05) to the FF group. A gait pattern is considered a cyclic movement, where the coordination of several joint movements concerning the same plane is necessary to optimize gait efficiency ([PERSON] et al., 2010). The increase in knee and hip flexion along gait for the FF subjects can result from a greater need to absorb impact that, in FF, are not absorbed at the foot level. This occurs because the FF subjects showed lesser ankle dorsiflexion and knee extension peak, corresponding to a lack of mobility. Finally, regarding the pelvic kinematics, the only significant difference concerning peak values was found relative to the pelvic rotation with an increased value in the FF over the NF group (\(p\) = 0.017). Finally, the FF group showed a significantly higher pelvic rotation ROM (\(p\) = 0.009). As stated by [PERSON] et al. (2010), our findings, regrouped with the comparison of the other studies related to an altered ankle and foot motion associated with foot posture, namely the FF condition, can induce altered motion over gait pattern ([PERSON] et al., 2015). The FF subjects exhibited a greater abduction and pronation in both static posture and during gait, which can increase injury risk. However, the FF subjects did not a present greater frontal plane motion ROM, i.e., abduction/adduction ROM. Therefore, without an increased amplitude, we can hypothesize that the FF subjects did not present greater ankle mobility during gait, which is contradictory to The key findings of several authors. In the systematic review concerning the kinematic differences between FF and NF subjects during gait conducted by [PERSON] et al. (2013), the authors provide some evidence of the relationship between the FF condition and lower limb motion during the gait. However, they only focus their analysis on the foot and ankle kinematics without an entire lower limb analysis.