Evaluation of standing stability in individuals with flatfeet

Abstract

OBJECTIVE: Flatfoot is one of the most common foot disorders, which not only influences the performance of the foot but also affects the alignments of the ankle, knee, and hip joints. The performance of the flat-arched individuals differs from that of normal individuals during walking. However, there is not enough information in the literature regarding their standing stability. Moreover, the influence of use of foot insole on standing stability has not been evaluated. Therefore, the aim of this study was to evaluate standing stability in individuals with flatfoot with and without insole. METHODS: Two groups of normal and flat-arched individuals were recruited into this study. A Kistler force plate was used to measure the center of pressure (CoP), which is recognized as a good approximation of sway of center of gravity in a horizontal plane. Stability was determined by calculating the CoP excursions, path length, and velocity in the mediolateral and anteroposterior directions. The difference between stability in normal individuals and those with flatfoot was examined using the independent t test. The paired t test was used to determine the difference between stability in each group with and without insole. Significant P value was set at alpha </=.05. RESULTS: There was a significant difference between stability of flat-arched and normal individuals based on CoP velocity and total velocity. In addition, there was no direct correlation between the severity of flatfoot and instability during quiet standing. However, the mean values of CoP total velocity during standing with and without insole were significantly different (P < .001). CONCLUSION: This study suggests that individuals with flatfoot are more unstable when compared with normal individuals during quiet standing. It seems that the foot insole improves the alignment of foot structure and reduces the forces applied on the ligament, thus, improving standing stability. Therefore, stability assessment in patients with flatfoot may be important, and the insole is a useful modality that can be used to improve stability in this patient group. LEVELS OF EVIDENCE: Therapeutic, Level II: Prospective, comparative trial.