Relationships Between Relative Ankle Muscle Ratios, Severity of Symptoms, and Radiologic Parameters in Adolescent Patients With Symptomatic Flexible Flat Feet

Abstract

Objective To investigate differences in the relative sizes of the ankle-stabilizing muscles in individuals with versus without flexible flat feet and to determine predictors of symptom severity.Methods This cross-sectional study included 30 patients with symptomatic flexible flat feet and 24 normal controls. The following were evaluated: foot posture index, resting calcaneal stance position angle, radiographic findings (calcaneal pitch, Meary’s angle, talocalcaneal angle, talonavicular coverage angle [TNCA]), foot function index (FFI), and cross-sectional areas (CSA) of the tibialis anterior (TA), tibialis posterior (TP), and peroneus longus (PL) upon ultrasonographic examination. To address morphometric differences among participants, individual muscle measurements were normalized to proportions of total muscle CSA. Between-group differences were evaluated with independent t-tests. Correlations between muscle ratios, radiographic parameters, and FFI scores were investigated. Logistic regression analysis was performed to determine which parameters predicted severe symptoms.Results The relative size of the TP was significantly greater and those of the TA and PL were significantly smaller in patients with flat feet than in normal controls. Correlations were found among relative muscle CSA ratios, radiographic parameters, and FFI score. Linear regression analysis confirmed that the TNCA and the relative CSA of the PL were independent predictors of symptom severity.Conclusion This study found significant differences in the relative CSAs of the ankle muscles in patients with flexible flat feet versus individuals without flat feet; these differences were significantly correlated with anatomic abnormalities. Symptoms were more severe in patients with relatively greater forefoot abduction and relatively smaller PL.

Effect of Foot Orthoses in Children With Symptomatic Flexible Flatfoot Based on Ultrasonography of the Ankle Invertor and Evertor Muscles

“…Ultrasonographic measurements: A physiatrist with at least 2 years of clinical experience in ultrasound examination measured the CSAs of the TA, TP, and PL using the ACUSON S2000 ultrasound unit (Siemens, Mountain View, CA, USA), with a linear probe with a frequency of 9–14 MHz. The CSA of each muscle was measured using a method described in previous studies [ 12 , 14 ]. The measurement locations were as follows: TA, one-third from the tibial tuberosity between the tibial tuberosity and the medial malleolus; TP, at the middle between the medial malleolus and the tibial tuberosity; and PL, one-third from the tibial tuberosity between the tibial tuberosity and the lateral malleolus ( Fig.…”

“…As muscles grow during childhood and adolescence and the rate of growth varies depending on age and sex [ 14 ], the ratio was calculated using the values measured with ultrasonography and the changes in the ratio of each muscle to the total area of the TA, TP, and PL were compared.…”

“…Using ultrasound, Sakamoto and Kudo [ 2 ] found that the activity of the abductor hallucis (AH), which is a forefoot adductor, increases to compensate for MLA collapse, and its CSA increases in patients with flatfoot. Shin et al [ 14 ] measured the CSAs of the tibialis anterior (TA) and tibialis posterior (TP) (ankle invertors) and PL (ankle evertor) in flatfoot patients using ultrasonography and compared the CSA ratio, which is the ratio of each muscle’s CSA to the total CSA of the TA, TP, and PL, combined. The CSA ratios of the TA and TP were higher and those of the PL were lower in individuals with flexible flatfoot than in those without.…”

“…Flatfoot has been reported to induce pain and fatigue during walking. However, the direct cause or mechanism by which flatfoot causes pain is unclear [ 14 - 16 ]. Most patients with flatfoot report pain in the sole and calves, and some report pain in the front and back of the knee and ankle [ 17 , 18 ].…”

“…Most patients with flatfoot report pain in the sole and calves, and some report pain in the front and back of the knee and ankle [ 17 , 18 ]. While a few studies have reported no correlations between the arch of the foot and pain among patients with flexible flatfoot [ 19 ], a study has shown significant correlations between pain severity and the PL ratio; this PL ratio is the ratio of CSA of the PL to the total CSA of the TA, TP, and PL, combined [ 14 ]. Conservative treatments are often administered to reduce pain and improve gait disability in patients with symptomatic flatfoot, including stretching exercises and foot orthoses [ 15 , 20 - 22 ].…”