# Gait Kinematics Analysis of Flatfoot Adults
## 4 Discussion  
FF is a condition that can be triggered by several reasons, namely, neurological or muscular restrictions, ligament laxity, joint laxity, excessive motion, and muscle activity [13; 33; 34; 35]. It is present in children, targets 10-25% of adults, and can be disastrous for patients as the foot problems prevalence has been reported to be from 46% to 80% in both clinical and institutional situations. This leads to several injuries, often accompanied by pain affecting gait pattern and speed, balance, and decreasing function, consequently increasing fall risk [1; 2; 33; 36; 37; 38; 3] The purpose of the present study was to characterize the gait kinematics during the entire gait cycle of subjects with FF conditions. Comparative observations of lower extremity kinematics during a walking task were performed between individuals with FF compared to those with NF. Gait was characterized in all three dimensions by employing a Motion Capture system. In this study, the group comparison showed statistically significant differences between most of the studied kinematic variables, more specifically for the ankle, knee, and hip joints. However, the Motion Capture analysis of gait kinematics and the complete lower limb analysis for FF subjects are not easily found in the literature. The current study provided a full assessment of the pelvis and the lower limbs to better characterize the movement in all three planes during gait. ROM differences have been found in the kinematics of both groups concerning the pelvis and all lower-limbs joints. In this study, FF participants presented lower ankle dorsiflexion (\(p\) = 0.029), abduction (\(p\) = 0.033), external and internal rotation (\(p\) < 0.001) during gait. Additionally, only the ankle abduction/adduction ROM presented a statistically significant increase in the NF group (\(p\) = 0.003). Those results follow those found by [PERSON] et al. (2012), who stated no significant differences (\(p\) > 0.05) between members of the the same group in the ankle kinematics during gait [20]. However, we need to highlight the fact that those results were found in children. In another study in children realized by [PERSON] et al. (2010), they found significant differences relative to the forefoot supination angle (\(p\) < 0.003). On the  
Figure 4: Center of mass variation of FF subjects alongside gait pattern. Figure 3: Center of mass variation of NF subjects alongside gait pattern. other hand, [PERSON] et al. (2010) investigated kinematic changes of the foot and the ankle along with the gait task in FF subjects compared to neutral ones in adults. They found a greater forefoot abduction (\(p\) = 0.002) and internal rotation (\(p\) = 0.018) in FF subjects. The authors found a significantly greater peak forefoot plantar flexion (\(p\) = 0.004) and adduction (\(p\) = 0.004). However, we found no adduction differences between the groups during the gait cycle (\(p\) = 0.398). This can be due to ankle stabilization during gait, namely during the propulsion phase in the late stance phase of the gait cycle. As noted by [PERSON] et al. (2010), the electromyography activity of the tibialis posterior is greater in FF subjects, which may explain the joint stabilization, not inducing a change both in foot pronation and ankle adduction ([PERSON] et al., 2015). Additionally, [PERSON] et al. (2015) investigated the kinematics of ankle and foot differences between FF and NF groups during gait. Their findings support a significantly smaller inversion/eversion ROM (\(p\) < 0.05) in the FF group as well as a significantly smaller peak plantar flexion value (\(p\) < 0.05). The authors performed a in systematic review concerning foot and ankle kinematics analysis during gait by comparing FF and NF subjects. Few papers were included in their review, and the authors stated that there was some evidence for increased motion in the FF subjects, but this was limited by small effect sizes.