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Gait & Posture

Volume 39, Issue 1, January 2014, Pages 23-28
Gait & Posture

ESMAC Runner up Award 2012
Does excessive flatfoot deformity affect function? A comparison between symptomatic and asymptomatic flatfeet using the Oxford Foot Model

https://doi.org/10.1016/j.gaitpost.2013.05.017Get rights and content

Abstract

Treatment of asymptomatic flexible flatfeet is a subject of great controversy. The purpose of this study was to examine foot function during walking in symptomatic (SFF) and asymptomatic (ASFF) flexible flatfeet. Thirty-five paediatric and juvenile patients with idiopathic flexible flatfeet were recruited from an orthopaedic outpatient department (14 SFF and 21 ASFF). Eleven age-matched participants with typically developing feet served as controls (TDF). To study foot function, 3D multi-segment foot kinematics and ankle joint kinetics were captured during barefoot gait analysis. Overall, alterations in foot kinematics in flatfeet were pronounced but differences between SFF and ASFF were not observed. Largest discriminatory effects between flatfeet and TDF were noticed in reduced hindfoot dorsiflexion as well as in increased forefoot supination and abduction. Upon clinical examination, restrictions in passive dorsiflexion in ASFF and SFF were significant. During gait, the hindfoot in flatfeet (both ASFF and SFF) was more everted, but less flexible. In sagittal plane, limited hindfoot dorsiflexion of ASFF and SFF was compensated for by increased forefoot mobility and a hypermobile hallux. Concerning ankle kinetics, SFF lacked positive joint energy for propulsion while ASFF needed to absorb more negative ankle joint energy during loading response. This may risk fatigue and overuse syndrome of anterior shank muscles in ASFF. Hence, despite a lack of symptoms flatfoot deformity in ASFF affected function. Yet, contrary to what was expected, SFF did not show greater deviations in 3D foot kinematics than ASFF. Symptoms may rather depend on tissue wear and subjective pain thresholds.

Introduction

Idiopathic flatfoot is a common finding in children and adolescents. Upon weight-bearing the heel is in valgus, the medial arch flattens and the forefoot deviates in abduction [1]. Deformity can be classified as flexible or rigid [2]. Experts agree that rigidity requires treatment [3].

Treatment in flexible flatfeet is however a subject of great controversy. Guidelines suggest to treat persistently symptomatic flexible flatfeet (SFF) only after ineffective conservative attempts [2], [4]. Asymptomatic flexible flatfeet (ASFF) are thought of as a physiological variant [5]. Prescribing orthotics or surgical intervention in ASFF is hotly debated [6], [7]. It has been suggested that after skeletal maturity initially ASFF might lose their flexibility risking secondary degeneration which could eventually require more complex surgical procedures [6], [8]. Besides, findings in adulthood show that flatfeet may be associated with knee pain [9], cartilage damage [10] and tibial stress syndrome [11]. It is therefore not unusual to find recommendations for preventive realignment in severe ASFF [12], while there in fact is no proof that untreated ASFF will become SFF [3].

Analysis of present foot function in ASFF is therefore of particular importance. It is generally assumed that flat footedness compromises walking [12]. While screening tests in schools pointed out that a low arch does not affect sport performance [13]. Clinical case series showed that about two-thirds of flexible flatfeet display symptoms and most ASFF report functional limitations [14]. This raises strong doubts that ASFF always function well [7]. In clinical practice, pathology is frequently evaluated by examination and radiological assessment. Although surgical approaches are recommended to be based on skeletal alignment [8], only the lateral talonavicular deviation seems to be clearly discriminative between ASFF and SFF [5]. Static radiographs do yet not indicate dynamic function.

Three-dimensional analysis of foot kinematics and kinetics during gait may be more suitable to study function and evaluate the degree of deformity. This had been already done by comparing flatfeet with typically developing feet (TDF) in paediatric and adult populations [15], [16], [17]. In children, ASFF have been characterized by increased supination of the forefoot [17]. In adults, ASFF displayed increased forefoot plantarflexion, abduction and larger hindfoot internal rotation [16]. SFF displayed increased forefoot abduction and an overall restraint in ROM [15]. While hindfoot eversion clinically appears very prominent, only one study showed a trend for increased eversion [16]. Concerning kinetics, it had been generally speculated that flat footedness affects shock absorption or propulsion [12]. Since there is a need to distinguish pathology from physiological variation, comparison between SFF and ASFF might be a promising to target indicators for pain.

The purpose of this study was to examine foot function during walking in symptomatic (SFF) and asymptomatic (ASFF) flatfeet. We aimed to discriminate 3D foot kinematics and kinetics in SFF and ASFF from TDF. First, we expected a kinematic continuum with SFF furthest deviating from TDF. Second, we expected a decline in flexibility, hence smaller ROM. Third, we hypothesized that both SFF and ASFF would be functionally limited and lacking shock absorption and propulsion.

Section snippets

Participants

Thirty-five children and adolescents with idiopathic flexible flatfeet at age 7 or older were included from our outpatient clinic. None had neuromuscular or neurogenic abnormalities. All were referred by general practitioners and depicted clinical findings of a bilateral valgus heel, a collapsed arch and a “too many toes” sign, with at least two of the three parameters graded as severe [12]. All flatfeet were classified as flexible showing heel inversion and a reconstituted arch during active

Results

Demographics are shown in Table 1. More males than females reported symptoms (10 vs. 4). Groups did not significantly differ on age, height or weight. BMI percentile appeared to be increased in flatfooted participants. Increases approached significance in ASFF (p = 0.06). Table 2 lists the symptoms and points out that SFF predominantly reported about pain (20/26) most often localized at the medial arch and at the Art. talocruralis. 6 SFF were not painful and reported only fatigue or discomfort.

Discussion

This study set out to distinguish foot function between symptomatic and asymptomatic paediatric and juvenile flexible flatfeet (SFF and ASFF) from typically developing feet (TDF). First, we found various considerable deviations in kinematics of flatfeet from TDF, but could overall not distinguish SFF from ASFF. Consequently, foot motion in SFF did not further deviate from the norm than in ASFF. Second, both type of flatfeet showed simultaneous constraint and excess in flexibility depending on

Conflict of interest statement

The authors of this manuscript declare no conflict of interest associated with this study.

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