Foot type biomechanics part 1: Structure and function of the asymptomatic foot

doi:10.1016/j.gaitpost.2012.09.007

Gait & Posture

Volume 37, Issue 3, March 2013, Pages 445-451

https://doi.org/10.1016/j.gaitpost.2012.09.007 Get rights and content

Abstract

Background

Differences in foot structure are thought to be associated with differences in foot function during movement. Many foot pathologies are of a biomechanical nature and often associated with foot type. Fundamental to the understanding of foot pathomechanics is the question: do different foot types have distinctly different structure and function?

Aim

To determine if objective measures of foot structure and function differ between planus, rectus and cavus foot types in asymptomatic individuals.

Methods

Sixty-one asymptomatic healthy adults between 18 and 77 years old, that had the same foot type bilaterally (44 planus feet, 54 rectus feet, and 24 cavus feet), were recruited. Structural and functional measurements were taken using custom equipment, an emed-x plantar pressure measuring device, a GaitMat II gait pattern measurement system, and a goniometer. Generalized Estimation Equation modeling was employed to determine if each dependent variable of foot structure and function was significantly different across foot type while accounting for potential dependencies between sides. Post hoc testing was performed to assess pair wise comparisons.

Results

Several measures of foot structure (malleolar valgus index and arch height index) were significantly different between foot types. Gait pattern parameters were invariant across foot types. Peak pressure, maximum force, pressure-time-integral, force-time-integral and contact area were significantly different in several medial forefoot and arch locations between foot types. Planus feet exhibited significantly different center of pressure excursion indices compared to rectus and cavus feet.

Conclusions

Planus, rectus and cavus feet exhibited significantly different measures of foot structure and function.

Highlights

► We investigated the structure and function of different foot types. ► 61 healthy individuals with 44 planus, 54 rectus, and 24 cavus feet were recruited. ► Measures of foot structure and function were different across foot types. ► Gait pattern parameters were invariant across foot types. ► Foot type should be used as a covariate in studies of lower extremity function.

Introduction

Differences in foot structure are postulated to be associated with differences in foot function during static posture or dynamic movement. Many foot pathologies are biomechanical in origin and often associated with foot type [1], [2], [3], [4]. Foot type is a clinical concept that aims to simplify the anatomical complexities of the human foot (28 bones, 33 joints, 112 ligaments, controlled by 13 extrinsic and 21 intrinsic muscles). As described in 1977 by Root, Orien, and Weed, clinicians can determine an individual's foot type by goniometric measurements of hind foot and forefoot alignments [5]. Foot type categorizes feet as planus (low arched with a valgus hindfoot and/or varus forefoot), rectus (well aligned hindfoot and forefoot), and cavus (high arched with a varus hindfoot and/or valgus forefoot) [5]. Planus feet generally over-pronate, causing the ground reaction forces (GRF) to move medially throughout the stance phase of gait, while cavus feet generally over-supinate, making the GRF move laterally throughout stance. Planus feet are associated with hallux valgus, hallux limitus and rigidus, and posterior tibial tendon dysfunction [1]. Furthermore, planus feet are considered a risk factor in the development of overuse injuries [4], [6], while cavus feet are associated with hammertoes and claw toe deformities [3], [7]. Rectus feet have not been directly associated with pathology or injury in the literature.

It is not clear why certain foot pathologies are associated with specific foot types or why some individuals with non-rectus foot types are asymptomatic. In order to systematically study foot pathologies, responses to treatment, and methods of prevention, objective measures of foot structure and function that differ between foot types are needed.

The purpose of this study was to determine if objective measures of foot structure and function are different for planus, rectus and cavus feet in asymptomatic individuals. Two hypotheses were formed: (1) measures of foot structure (malleolar valgus index, arch height indices, and arch height flexibility) will be different across foot types and (2) measures of foot function (center of pressure excursion index, peak pressure, maximum force, pressure-time-integral, force-time-integral, and contact area) will be different across foot types. Foot type will serve as the independent variable while foot structure and function are the dependent variables.

Section snippets

Methods

All procedures were approved by the Institutional Review Board. All enrolled individuals signed a consent form and were provided minimal compensation for expenses. Testing was performed within the motion analysis laboratory.

Test subject demographics

Sixty-one test subjects were enrolled in this study with the following characteristics:

•
planus – 22 subjects, 44 feet, 12 females, height = 1.7 ± 0.1 m, weight = 675.4 ± 146.9 N, BMI = 23.3 ± 4.3 kg/m², age = 35.6 ± 11.0 years
•
rectus – 27 subjects, 54 feet, 19 females, height = 1.7 ± 0.1 m, weight = 662.6 ± 138.7 N, BMI = 24.4 ± 4.1 kg/m², age = 33.1 ± 9.8 years
•
cavus – 12 subjects, 24 feet, 6 female, height = 1.7 ± 0.1 m, weight = 720.8 ± 155.0 N, BMI = 24.0 ± 3.5 kg/m², age = 42.8 ± 16.2 years

The subjects in each group had similar characteristics with

Why study foot types?

Given that individuals with excessive pronation (planus) or supination (cavus) tend to be more vulnerable to certain pathologies, an understanding of the biomechanics associated with different foot types is warranted [13]. In military and athletic populations, cavus and planus foot types are associated with increased risk of tibial stress injuries as compared to rectus foot type [6], [14]. Individuals with diabetes and peripheral polyneuropathy are at risk for developing neuropathic foot

Summary

A study of healthy asymptomatic individuals with planus, rectus, and cavus feet was conducted to determine if foot structure and function were sensitive to foot type. Several reliable measures of foot structure and function differed across foot type. Hindfoot alignment, as measured by MVI, was significantly larger in planus feet compared with rectus and cavus feet. AHI, sitting or standing, was able to distinguish each foot type. Gait pattern parameters were invariant to foot type. Dynamic

Conflict of interest

None.

Ethical approval

This study was approved by the Institutional Review Board at the Hospital for Special Surgery.

Acknowledgements

This study was supported by the NICHD-NCMRR (1R03HD053135-01) and NIAMS (R01AR047853-10). The assistance and expertise of Mark Lenhoff, BS, Sherry I Backus, PT, DPT, MA, David Gagnon, MD, MPH, PhD, Sonali Rajan, Ph.D., and Andrea Woodley, MS is gratefully acknowledged.

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Is Morton's neuroma in a pes planus or pes cavus foot lead to differences in pressure distribution and gait parameters?
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Morton's neuroma (MN) is a compressive neuropathy of the common digital plantar nerve causing forefoot pain. Foot posture and altered plantar pressure distribution have been identified as predispoing factors, however no studies have compared individuls with different foot postures with MN. Thus, we aimed to compare the effect of MN on spatiotemporal gait parameters and foot-pressure distribution in individuals with pes planus and pes cavus. Thirty-eight patients with unilateral MN were evaluated between June and August 2021. Nineteen patients with bilateral pes planus and 19 age and gender-matched patients with pes cavus who had no prior surgery were recruited. A Zebris FDM–THM–S treadmill system (Zebris Medical GmbH, Germany) was used to evaluate step length, stride length, step width, step time, stride time, cadence, velocity, foot-pressure distribution, force and whole stance phase, loading response, mid stance, pre-swing and swing phase percentages. There were no significant differences between the groups in spatiotemporal gait parameters (p > 0.05). Patients with pes planus displayed the following results for step length (49.36 ± 8.38), step width (9.05 ± 2.12), stance phase percentage (65.92 ± 2.11), swing phase percentage (34.08 ± 2.12), gait speed (2.96 ± 0.55), and cadence (100.57 ± 8.84). In contrast, patients with pes cavus displayed the following results for step length (49.06 ± 8.37), step width (8.10 ± 2.46), stance phase percentage (64.96 ± 1.61), swing phase percentage (34.79 ± 1.60), gait speed (2.95 ± 0.65), and cadence (99.73 ± 13.81). Foot-pressure distribution values showed no differences were detected in force, forefoot, and rearfoot pressure distribution, except for midfoot force (p < 0.05). The forefoot, midfoot, and rearfoot pressure values for the pronated group were 32.14 ± 10.90, 13.80 ± 3.03, and 22.78 ± 5.10, and for the supinated group were 33.50 ± 11.49, 14.23 ± 3.11 and 24.93 ± 6.52. MN does not significantly affect spatiotemporal gait parameters or foot-pressure distribution in patients with pes cavus or pes planus.
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Une prévalence élevée de troubles au pied rapportés chez les marcheurs de longue distance a été observée. Or, aucune documentation ne semble décrire comment se manifeste l’adaptation du pied à un volume soutenu de marche dans le temps. Le but de l’étude est de quantifier les modulations morpho-fonctionnelles du pied peu de jours après une période de marche au long cours. L’étude recense aussi les effets différenciés reliés au sexe, à la latéralité du membre inférieur (dominant vs non dominant) et à l’ampleur du trajet pédestre.
Les données de 38 marcheurs-pèlerins (âge : 63,2 ± 7,8 ans ; 57,9 % de femmes ; IMC : 25,7 ± 3,8 kg/m²) ont été recueillies lors de trois collectes en laboratoire (C₁, C₂, C₃), intercalées d’une période de marche au long cours. La collecte initiale C₁ avait lieu à l’intérieur des 30 jours avant la marche. La collecte C₂, tenue 5 à 10 jours après C₁, servait à quantifier le changement minimal détectable (CMD) pour chaque variable dépendante. La collecte C₃ (de suivi) prenait place au maximum 10 jours après la marche. Quatre types de regroupement ont été formés selon les trajets pédestres réalisés : cohorte au long cours (parcours ≥ 250 km) [LC, n = 31], groupes court trajet (parcours de 200 à 450 km) [CT, n = 15], moyen trajet (parcours de 450 à 900 km) [MT, n = 10] et long trajet (parcours ≥ 900 km) [LT, n = 8]. L’étude de la cohorte LC sert à cibler les effets spécifiques au contexte de marche, la comparaison des groupes CT, MT, LT permet d’en dégager les effets associés au cumul de marche. Les analyses de variance traitent séparément les facteurs sexe et latéralité. Pour la cohorte LC, l’éventuelle différence significative (p ≤ 0,05) entre C₁ et C₃ doit aussi être confirmée par un changement moyen de la mesure qui soit d’une ampleur supérieure au seuil critique (valeur du CMD.n) pour que le changement soit considéré réel. Sept variables dépendantes sont testées : la longueur du pied et du pied tronqué, la largeur du pied aux têtes métatarsiennes, l’indice MVI, la hauteur du naviculaire et du dos du pied, et le ratio AHI.
Une diminution significative de la longueur du pied (−0,8 ± 1,9 mm ; −0,34 % ; CMD.n = 0,7 mm) du côté du membre inférieur dominant (F_1,29 = 4,95 ; p = 0,034) a été observée entre C₁ et C₃ pour la cohorte LC. Dans la même cohorte, un effet d’interaction significatif a été noté pour la largeur du pied (F_1,29 = 4,64 ; p = 0,040) : chez l’homme, une augmentation significative (+1,4 ± 1,6 mm ; +1,35 % ; CMD.n = 0,7 mm) de C₁ à C₃ est observée, alors qu’une tendance opposée apparaît chez la femme. Ces effets sont considérés de réels changements induits par la marche, leur ampleur se chiffrant au-dessus des seuils critiques calculés. Les analyses considérant les groupes CT, MT, LT ne révèlent aucun effet relatif à l’ampleur des trajets pédestres.
Cette étude montre que quelques dimensions morpho-fonctionnelles du pied sont finement impactées par la marche au long cours considérant les volumes de pratique rapportés. Les résultats mettent en lumière que le sexe et la dominance du membre inférieur sont à considérer pour décrire avec justesse les modulations au pied induites par la marche de longue durée. D’autres études sont indiquées pour mieux comprendre les mécanismes pathogéniques des troubles au pied rapportés par les marcheurs au long cours.
A high prevalence of foot disorders reported in long-distance walkers has been observed. However, we found no documentation on how the foot adapts to a sustained walking volume over time. The aim of the study was to quantify the morpho-functional modulations of the foot shortly after a period of long-term walking. The study also investigates differential effects related to gender, lower limb laterality (dominant vs. non-dominant), and to the extent of the pedestrian path covered.
Data from 38 pilgrim-walkers (age: 63.2 ± 7.8 years; 57.9% women; BMI: 25.7 ± 3.8 kg/m²) were collected during three lab data collection (C₁, C₂, C₃), interspersed with a long-term walk. The baseline data collection C₁ took place within 30 days before the walk. The C₂ data collection, held 5-10 days after C₁, was used to quantify the minimum detectable change (MDC) for each dependent variable. The C₃ (follow-up) data collection took place up to 10 days after the walk. Four groups were formed based on the extent of the pedestrian routes covered: long-term cohort (path ≥ 250 km) [LT, n = 31], short-path group (path from 200 to 450 km) [SP, n = 15], medium-path group (path from 450 to 900 km) [MP, n = 10] and long-path group (path ≥ 900 km) [LP, n = 8]. Studying the LC cohort serves to target the effects specific to the walking context, while comparing groups SP, MP, LP allows the cumulative effects to be identified. Analyses of variance treat the factors gender and laterality separately. For the LC cohort, a possible of significant difference (P ≤ 0.05) between C₁ and C₃ must also be ratified by an average change in the measure that is greater than the critical threshold (MDC.n value) for the change to be considered real. Seven dependent variables are tested: foot length and truncated foot length, foot width at the metatarsal heads, MVI index, navicular height, dorsum of foot height and AHI ratio.
A significant decrease in foot length (−0.8 ± 1.9 mm; −0.34% MDC.n = 0.7 mm) on the side of the dominant lower limb (F_1.29 = 4.95; P = 0.034) was observed between C₁ and C₃ for the LC cohort. In the same cohort, a significant interaction effect was noted for foot width (F_1.29 = 4.64; P = 0.040): in men, a significant increase (+1.4 ± 1.6 mm; +1.35%; MDC.n = 0.7 mm) from C₁ to C₃ is observed while a reverse trend appears in woman. These effects are considered real changes induced by walking: their magnitude being above the calculated critical thresholds. Analyses considering the SP, MP, LP groups showed no effect relative to the extent of the pedestrian routes covered.
The changes observed in this study show that some morpho-functional dimensions of the foot are finely impacted by long-term walking considering the reported volumes of practice. Results highlight that the walker's gender and lower limb dominance should be considered to accurately describe the foot modulations induced by long-term walking. Further studies are indicated to better understand the pathogenic mechanisms of foot disorders reported by long-term walkers.

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Foot type biomechanics part 1: Structure and function of the asymptomatic foot

Abstract

Background

Aim

Methods

Results

Conclusions

Highlights

Introduction

Section snippets

Methods

Test subject demographics

Why study foot types?

Summary

Conflict of interest

Ethical approval

Acknowledgements

Orthopaedics & Traumatology: Surgery & Research

Journal of Foot and Ankle Surgery

Foot

Gait and Posture

Biomechanical differences among pes cavus, neutrally aligned, and pes planus feet in subjects with diabetes

Foot and Ankle International

Taylor DC and temple HT Incidence of foot and ankle injuries in West Point cadets with pes planus compared to the general cadet population

Foot and Ankle International

The effect of foot structure and range of motion on musculoskeletal overuse injuries

American Journal of Sports Medicine

The normal and pathological foot. Concepts of anatomy, physiology and pathology of foot deformities

Acta Orthopaedica Belgica