Category: Basic Sciences/Biologics, Midfoot/Forefoot Introduction/Purpose: In the flatfoot patients, collapsed medial longitudinal arch during gait induced pain and it results decreased center of progression excursion index(CPEI) in dynamic pedobarography. Although the CPEI decreased is pathologic gait of flatfoot patients, range of the CPEIs is wide even in similar severity of flatfoot patients. We hypothesized that some flatfoot patients inverted forefoot or elevated first metatarsal head during gait for avoiding the pain from collapsed medial longitudinal arch, which resulted wide range of the CPEIs in flatfoot patients. The purposes of this study were to investigate the incidence of forefoot inversion and 1st metatarsal head elevation during gait in severe symptomatic flatfoot patients, and to confirm whether forefoot inversion and 1st metatarsal head elevation increases the CPEI, by using the dynamic pedobarography. Methods: We retrospectively evaluated patients who underwent surgery for flatfoot in our clinic from January, 2017 to May, 2017. Before surgery, all patients underwent plain weight-bearing radiographs and dynamic pedobarography by using in-shoe plantar pressure assessment system (Tekscan, Inc., South Boston, MA). Radiographic parameters, talonavicular coverage angle, Meary angle and moment arm, and the CPEI in dynamic pedobarogrpahy were measured. The forefoot inversion and the 1st metatarsal head elevation were defined when sum of 3rd-4th and 5th submetatarsal plantar pressure was higher than sum of 1st and 2nd submetatarsal plantar pressure, and when 2nd submetatarsal plantar pressure was higher than 1st submetatarsal plantar pressure, respectively. Correlations between the radiographic parameters and the CPEI were investigated. Incidence of the forefoot inversion and the 1st metatarsal head elevation was investigated. The CPEIs in flatfeet with forefoot inversion or 1st metatarsal head elevation were compared with those in flatfeet without these pain avoidance gait. Results: Twenty-eight flatfeet from 28 patients were included in the present study. The average age of patients was 42.3 years (range: 19-71). Means of the three radiographic parameters and the CPEI of the 28 flatfeet were listed at table.1. There was no significant correlation between the CPEI and the three radiographic parameters.(Table.2) The incidence of forefoot inversion and 1st metatarsal head elevation were 11%(3 feet), 54%(15 feet) respectively. The mean CPEI of the flatfeet with forefoot inversion or 1st metatarsal head elevation was 8(range: -10 – 18), and the mean CPEI of the flatfeet without these two compensations was 5 (range: -3 – 12). The CPEI in the flatfeet with the two compensations was significant larger than that of the flatfeet without the two compensations. (P=0.027) Conclusion: In the present study, forefoot inversion or 1st metatarsal head elevation were happened in 65% of symptomatic flatfoot patients. These two pain avoidance gait shifts weight-bearing load laterally, which decreases collapsing medial longitudinal arch and pain on the flatfoot. Because lateral shifting of weight-bearing load increases the CPEI, flatfoot patients with these two gaits showed high the CPEI. Therefore, the degree of the CPEIs are various even in similar severity of flatfoot and are not correlated with the severity of the flatfoot. Clinicians should consider these pain avoidance gait of flatfoot patients when they interpret a dynamic pedobarography of flatfoot.
Age-related decrements in cycling and running performance
