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

Ultrasound assessment of distal femoral cartilage thickness measurements after walking/jogging in subjects with pes planus

BACKGROUND

Because there is a closed kinematic chain between the lower extremity joints during weight-bearing activities, pes planus can affect knee biomechanics.

OBJECTIVE

This study aimed to measure distal femoral cartilage thickness with ultrasound after 3 different conditions (at rest, during walking and jogging) in subjects with pes planus and compare these conditions with each other and also with controls.

METHOD

Sixteen participants with pes planus(5-men, 11-women; aged 18-30 years) and 16 controls(3-men, 13-women; aged 18-30 years) were enrolled. Distal femoral cartilage thickness was evaluated with ultrasound before and after three separate 30-min conditions. Preferred walking speed (PWS) was determined on the ground. Subjects walked on a treadmill for 30-min at their PWS and jogged 30-min at 30% above their PWS. The Foot Function Index and the Foot-Ankle Outcome Survey were used to evaluate the clinical and functional status of the subjects.

RESULTS

Neither PWSs nor jogging speeds were statistically different between groups (p > 0.05). There were no statistically significant differences between groups for absolute and percent change of cartilage thickness for all three conditions (p > 0.05). There were also no statistically significant differences between conditions for each intragroup (p > 0.05). The median Foot Function Index score of the subjects with pes planus was 9.78(0-44.35) for the right foot and 9.52(0-40.87) for the left foot. The median the Foot-Ankle Outcome Survey score of the subjects with pes planus was 88(65-100).

CONCLUSION

There was no difference in knee joint cartilage deformations under different loading conditions, neither in subjects with pes planus nor in controls.

The association between foot posture, single leg balance and running biomechanics of the foot

OBJECTIVES

A mal-aligned foot posture (high-arched and flat feet) and poor single leg balance ability have been separately associated with foot injuries during running. Therefore, clinicians assess these routinely. However, the extent to which foot posture and single-leg balance ability affect actual foot biomechanics during running is not known. This study aims to investigate the association of foot posture, single-leg balance ability, and foot biomechanics during running.

METHOD

This is a cross sectional study of sixty-nine participants who had their foot postures and single-leg balance ability assessed. The Foot Posture Index and Balance Error Scoring System were used. Their foot kinetics was measured as they ran on an instrumented treadmill and foot kinematics was processed using a 3D motion capture system. Multiple-regression was used to analyse the variance of foot biomechanics explained by foot posture and single-leg balance ability.

RESULTS

Foot posture and single-leg balance ability were found to account significantly for the variance in rearfoot eversion (24%) and forefoot dorsiflexion (7%). Two regression equations were derived, where rearfoot eversion and forefoot dorsiflexion during running may be predicted.

CONCLUSION

Foot posture and single-leg balance ability can predict rearfoot eversion and forefoot dorsiflexion only during running. Based on the regression equations, individuals with the same foot posture but different single-leg balance ability may exhibit different foot kinematics. However, the angular differences are small. The equations may be useful for clinicians working in places where running gait analysis equipment are not readily accessible. Further studies with larger sample sizes are required to validate these equations. In addition, further studies are necessary to investigate the effect of these two variables under different running conditions e.g. with footwear and with orthoses.

New Distinct Component Patterns for Plantar Pressure Variables by Using Principal Component Analysis

BACKGROUND

It is important to determine the plantar pressure distribution of schoolchildren by applying static and dynamic foot analyses using a pedobarography device. However, it is difficult to obtain clear interpretations from results that can be explained by a large number of plantar pressure variables. The aim of this study was to use principal component analysis (PCA) to predict the main components for reducing the size of big data sets, provide a practical overview, and minimize information loss on the subject of plantar pressure assessment in youths.

METHODS

In total, 112 schoolchildren were included in the study (mean ± SD: age, 10.58 ± 1.27 years; body mass index, 18.86 ± 4.33). During the research, a pedobarography device was used to obtain plantar pressure data. Each foot was divided into six anatomical regions and evaluated. Global and regional plantar pressure distributions, load and surface areas, pressure-time integrals, weight ratios, and geometric foot properties were calculated.

RESULTS

The PCA yielded ten principal components that together account for 81.88% of the variation in the data set and represent new and distinct patterns. Thus, 137 variables affecting the subject were reduced to ten components.

CONCLUSIONS

The numerous variables that affect static and dynamic plantar pressure distributions can be reduced to ten components by PCA, making the research results more concise and understandable.

Validity and inter-rater reliability of ankle motion observed during a single leg squat

BACKGROUND

The single leg squat (SLS) test is a clinical functional test commonly used to evaluate clinically aberrant movement patterns of the knee. The SLS could be an interesting option to analyze ankle control in the frontal plane during dynamic load analysis. However, to date, there are no studies that have analyzed the associations between the increased subtalar joint pronation by navicular drop (ND) test and ankle control with single leg squat (SLS_ankle) using a three-point scale. The purpose of this study was to evaluate the reliability of a clinical observation method to assess and determine the relationship between navicular drop (ND) and ankle control on the SLS_ankle score.

METHODS

A total of fifty-five healthy, physically active (31 females and 24 males) volunteers participated in this study. The degree of subtalar pronation was assessed through the ND test, and the ankle control was defined as the ankle displacement in the frontal plane during the SLS.

RESULTS

We found good intra-rater and inter-rater agreement during SLS_ankle, with Kappa values from 0.731 to 0.750. The relationship between the SLS_ankle and ND was significant ; the Spearman's rank correlation coefficient was 0.504 (p < 0.05).

CONCLUSIONS

The SLS_ankle score supplied the clinical practice with a reliable and valid alternative for quantifying foot mobility in comparison to the ND test.

Is the Planus Foot Type Associated With First Ray Hypermobility?

Background:

Many foot pathologies have been associated with foot type. However, the association of first ray hypermobility remains enigmatic. The purpose of this study was to investigate first ray hypermobility among participants with planus and rectus foot types and its influence on static measures of foot structure.

Methods:

Twenty asymptomatic participants with planus (n = 23 feet) and rectus (n = 17 feet) foot types were enrolled. Several parameters of static foot structure (arch height index, arch height flexibility, first metatarsophalangeal joint flexibility, and first ray mobility) were measured. Participants were further stratified into groups with nonhypermobile (n = 26 feet) and hypermobile (n = 14 feet) first rays. First ray mobility ≥8 mm was used to define “first ray hypermobility”. Generalized estimating equations, best-fit regression lines, and stepwise linear regression were used to identify significant differences and predictors between the study variables

Results:

Overall, 86% of subjects categorized with first ray hypermobility exhibited a planus foot type. Arch height flexibility, weightbearing first ray mobility, and first metatarsophalangeal joint flexibility showed no significant between-group differences. However, weightbearing ray mobility and first metatarsophalangeal joint laxity were associated with partial weightbearing first ray mobility, accounting for 38% of the model variance.

Conclusion:

The planus foot type was found to be associated with first ray hypermobility. Furthermore, weightbearing first ray mobility and first metatarsophalangeal joint laxity were predictive of partial weightbearing first ray mobility, demonstrating an interaction between the translation and rotational mechanics of the first ray.

Clinical Relevance:

Association of first ray hypermobility with foot type and first metatarsophalangeal joint flexibility may help understand the sequela to symptomatic pathologies of the foot.

The Association Between Foot Structure and Foot Kinematics During Slow Running

BACKGROUND

Clinicians routinely assess foot posture as part of their assessment and management of foot pathologies. Flat or high-arched foot postures have been linked to kinematic deviations and increased risk of foot injuries. The Foot Posture Index (FPI) is a valid clinical tool used to classify feet into high-arched, normal-arched, and flat foot groups and predicts foot function during walking well. Walking and running are distinct locomotion styles, and studies have not been performed to correlate FPI to foot function during running. This study aims to investigate the association of FPI scores to foot kinematics during running. The results will further inform clinicians who perform static assessment of feet of individuals who are runners.

METHODS

Sixty-nine participants had their feet assessed using the FPI scoring system. Based on these scores, the feet were categorized as flat foot, normal-arched, and high-arched. Rearfoot eversion and forefoot dorsiflexion (arch flattening) of the foot were analysed during slow running between 1.4 and 2.2 m/sec. The Pearson correlation was used to analyse the FPI scores on an interval scale, with Cohen's d used to report effect size. One-way analysis of variance and a Bonferroni post hoc test was used to analyze data by category. Level of significance was set at P < .05.

RESULTS

Thirty-four flat feet, 26 normal-arched feet, and nine high-arched feet were analyzed. The FPI scores correlated significantly with rearfoot eversion (moderate effect size) and forefoot dorsiflexion (low effect size). Rearfoot eversion was greatest in the flat foot, followed by the normal-arched foot and the high-arched foot. Forefoot dorsiflexion was significantly higher in the flat foot compared with the high-arched group.

CONCLUSIONS

Foot Posture Index scores are positively correlated with rearfoot eversion and forefoot dorsiflexion during running. Clinicians can use this information to aid their foot assessment and management of individuals who are runners.

Risk factors for musculoskeletal injuries in the military: a qualitative systematic review of the literature from the past two decades and a new prioritizing injury model

BACKGROUND

Musculoskeletal injuries (MSkIs) are a leading cause of health care utilization, as well as limited duty and disability in the US military and other armed forces. MSkIs affect members of the military during initial training, operational training, and deployment and have a direct negative impact on overall troop readiness. Currently, a systematic overview of all risk factors for MSkIs in the military is not available.

METHODS

A systematic literature search was carried out using the PubMed, Ovid/Medline, and Web of Science databases from January 1, 2000 to September 10, 2019. Additionally, a reference list scan was performed (using the "snowball method"). Thereafter, an international, multidisciplinary expert panel scored the level of evidence per risk factor, and a classification of modifiable/non-modifiable was made.

RESULTS

In total, 176 original papers and 3 meta-analyses were included in the review. A list of 57 reported potential risk factors was formed. For 21 risk factors, the level of evidence was considered moderate or strong. Based on this literature review and an in-depth analysis, the expert panel developed a model to display the most relevant risk factors identified, introducing the idea of the "order of importance" and including concepts that are modifiable/non-modifiable, as well as extrinsic/intrinsic risk factors.

CONCLUSIONS

This is the qualitative systematic review of studies on risk factors for MSkIs in the military that has attempted to be all-inclusive. A total of 57 different potential risk factors were identified, and a new, prioritizing injury model was developed. This model may help us to understand risk factors that can be addressed, and in which order they should be prioritized when planning intervention strategies within military groups.

Arch-Support Induced Changes in Foot-Ankle Coordination in Young Males with Flatfoot during Unplanned Gait Termination

Objective: The efficacy of arch orthoses in posture adjustment and joint coordination improvement during steady-state gait is well documented; however, the biomechanical changes of gait sub-tasks caused by arch support (AS), especially during gait termination, are poorly understood. Hence, this study aimed to investigate how the acute arch-supporting intervention affects foot–ankle coordination and coordination variability (CV) in individuals with flatfoot during unplanned gait termination (UGT). Methods: Twenty-five male patients with flatfoot were selected as subjects participated in this AS manipulation study. A motion capture system was used for the collection of the metatarsophalangeal joint (MPJ) and ankle kinematics during UGT. MPJ-Ankle coordination and CV were quantified using an optimized vector coding technique during the three sub-phases of UGT. A paired-sample t-test from the one-dimensional statistical parametric mapping of one-dimensional was applied to examine the data significance. Results: Significant differences for the joint kinematics between non-arch-support (NAS) and AS were exhibited only in the MPJ transverse plane during the middle and later periods of UGT (p = 0.04–0.026). Frontal plane MPJ-ankle coordination under AS during stimulus delay significantly decreased from 177.16 ± 27.41° to 157.75 ± 32.54° compared with under NAS (p = 0.026); however, the coordination pattern had not changed. Moreover, no significant difference was found in the coupling angle variability between NAS and AS in three planes during sub-phases of UGT (all p > 0.5). Conclusions: The detailed intrinsic characteristic of AS induced acute changes in lower extremity segment coordination in patients with mild flatfoot has been recorded. This dataset on foot-ankle coordination characteristics during UGT is essential for explaining foot function and injury prediction concerning AS manipulation. Further studies are expected to reflect lower limb inter-joint coordination during gait termination through the long-term effects of AS orthoses.

Comparing Validity and Diagnostic Accuracy of Clarke's Angle and Foot Posture Index-6 to Determine Flexible Flatfoot in Adolescents: A Cross-Sectional Investigation

OBJECTIVE

Clinically, the foot posture index-6 (FPI-6) and Clarke's angle (CA) are widely utilized to assess static foot posture; however, due to scarcity of scientific evidence, clinicians continue to debate the validity and diagnostic accuracy of these measures in children and adolescents. This study aimed to evaluate and compare the validity and diagnostic accuracy of the FPI-6 and CA in determining adolescents' flexible flatfoot between ages of 12 and 18 years, considering radiographic investigation as a reference standard measure.

DESIGN

Cross-sectional study.

SETTING

Governmental hospitals.

PARTICIPANTS AND METHODS

A sample of 460 people (920 feet) with flexible flatfoot between the ages of 12 and 18 (15.23 ± 0.84 years) was enrolled in the study. The findings of the investigated measures were compared to the reference standard radiographic measure and plotted on the receiver operating characteristic (ROC) curve. The area under the ROC curve (AUC) was determined as a measure of FPI-6 and CA diagnostic accuracy. Intra-rater reliability, sensitivity, specificity, predictive values, and likelihood ratios of FPI-6 and CA were calculated and compared. The post-test probability of flatfoot was determined using the Fagan nomogram.

RESULTS

CA had a substantially higher intra-rater reliability (ICC=0.99) than the FPI-6 (ICC=0.96), with p-value of 0.001. CA has greater sensitivity (98%) than FPI-6, as well as a superior specificity (99%), positive predictive value (98%), negative predictive value (98.9%), positive likelihood ratio (97), and a lower negative likelihood ratio (0.02). CA had such an area under ROC curve of 0.98 with a 95% confidence interval of 0.95-1.00, while FPI-6 had an area under ROC curve of 0.80 with a 95% confidence interval of (0.77-0.85).

CONCLUSION

FPI-6 and Clarke's angle are both valid and diagnostically accurate clinical tests for flatfoot detection, with Clarke's angle outperforming FPI-6 in adolescents aged 12 to 18 years with a normal BMI.

A Retrospective Study of Foot Biomechanics and Injury History in Varsity Football Athletes at the U.S. Naval Academy

INTRODUCTION

The six-item Foot Posture Index (FPI-6) was previously developed as an assessment tool to measure the posture of the foot across multiple segments and planes. It was derived from a criterion-based observational assessment of six components of each foot during static standing. The association between abnormal foot posture and musculoskeletal injuries remains unclear and is in of need further exploration.

HYPOTHESIS/PURPOSE

The purpose of this study was to assess the association between foot biomechanics and self-reported history of musculoskeletal pain or injury.

STUDY DESIGN

Retrospective, cross-sectional study of collegiate football players at the U.S. Naval Academy.

MATERIALS AND METHODS

For each athlete, data were recorded on height, weight, self-reported history of pain or injury, and foot posture, which was measured using a FPI-6 with each item measuring the degree of pronation/supination. The primary outcome was each athlete's maximum deviation from neutral posture across the six-item index (FPImax). The prespecified primary analysis used generalized linear models to measure the association between FPImax and self-report history of pain or injury. Exploratory analyses measured the association using penalized regression (L1-norm) and a type of tree-based ensemble known as extreme gradient boosting (XGBoost).

RESULTS

Data were collected on 101 athletes, 99 of whom had sufficient body mass index (BMI) data to be included for analysis. Among the 99 athletes, higher FPImax was associated with a prior history of musculoskeletal pain (odds ratio [OR] 1.15, 95% confidence interval [CI] 0.97 to 1.35), although the sample size was too small for the association to be significant with 95% CI (P = .107). FPImax was not associated with a history of knee injury/pain (OR 0.98, 95% CI 0.83 to 1.15, P = .792), nor with a history of ankle/foot injury or pain (OR 1.04, 95% CI 0.90 to 1.21, P = .599). From the L1-penalized model, the FPI components with the strongest linear associations were the L6, R2, R1-squared, and FPImax. From the XGBoost model, the most important variables were FPItotal, BMI, R1, and R2.

CONCLUSIONS

The U.S. Naval Academy football players whose foot postures deviated from neutral were more likely to have reported a previous history of musculoskeletal pain. However, this deviation from normal was not strongly associated with a specific history of pain or injury to the knee, ankle, or foot.

CLINICAL RELEVANCE

The information ascertained from this study could be used to better inform clinicians about the value of the FPI in predicting or mitigating injuries for varsity football athletes.

Influence of the medial longitudinal arch of the foot in adult women in ankle isokinetic performance: a cross-sectional study

BACKGROUND

Maintenance of the medial longitudinal arch (MLA) of the foot is fundamental during functional tasks and disorders can lead to clinical alterations. Studies have demonstrated that deficits in ankle isokinetic performance can predispose an individual to lower limb injuries.

OBJECTIVES

To evaluate the muscular performance of cavus, planus, and normal feet by means of torque/body mass and the isokinetic phases, to generate 3D surface map analysis, and to verify whether there is a relationship between MLA height and arch height flexibility with isokinetic performance.

METHODS

The sample consisted of 105 healthy adult women, divided into three groups: normal, cavus, and planus. Assessment in concentric mode at 30, 60, and 90 °/s in the dorsiflexion and plantarflexion of the ankle joint were analyzed during the three isokinetic phases (acceleration, sustained velocity, and deceleration). The variables total range of motion, peak of torque (PT), and angle of PT were extracted within the sustained velocity.

RESULTS

In dorsiflexion at 60 °/s, the phase where the velocicty is sustained (load range phase) was higher in the planus group (M_eanD_ifference=10.9 %; ω²_p = 0.06) when compared with the cavus group. Deficits in the peak torque/body mass in dorsiflexion at 60 °/s (cavus feet: MD=-3 N.m/kg; ω²_p = 0.06; and planus feet: MD=-1.1 N.m/kg; ω²_p = 0.06) were also observed as well as in the 3D surface maps, when compared with the normal group. The flexibility of MLA had a negative correlation of PT at 30 °/s in cavus group. The heigth of MLA had a postive correlation with the PT for the cavus and planus group ate 60 °/s. All other results did not show differences between the groups.

CONCLUSIONS

The planus groups showed a better capacity of attain and sustained the velocity in dorsiflexion in relation the cavus group. The cavus and planus group had deficts in torque in relation the normal. The correlations were weak between the measures of MLA and PT. Thereby, in general the differences between foot types showed small effect in isokinetic muscle performance measures of the plantar and dorsi flexores.

TRIAL REGISTRATION

Study design was approved by the IRB (#90238618.8.0000.5231).

The development of the medial longitudinal arch in the intrauterine period

In this study, we aimed to reveal whether the medial longitudinal arch is formed in the intrauterine period and the structural features of the medial longitudinal arch. The study was conducted on 146 feet of 73 fetuses (38 male, 35 female) aged between 15 and 40 weeks of gestation. The fetuses were grouped by trimesters. The footprints taken were photographed with a millimeter ruler, and the development of the medial longitudinal arch was examined on footprints based on the Clarke index, Chipaux-Smirak index, and Staheli index. In Clarke index and Staheli index, it was observed that the arch height was normalized in the transition from the second trimester to the third trimester, the arch decreased in the transition to full-term, and the rate of pes planus increased. All indices detected pes planus by 81.81% in the full-term period. The rate of pes planus determined according to Clarke index and Staheli index, especially in the third trimester period, was 6.94% and 11.11%, respectively. We have provided a perspective on how the development of the medial longitudinal arch is shaped in the intrauterine period. Based on the results of study, we consider that the data on the medial longitudinal arch, especially in the third trimester period, may be more significant. In the evaluations made from the footprints of premature infants in the intrauterine third trimester period in the future, a study, in which infants detected with pes planus can be followed up and the development of their medial longitudinal arch is evaluated, can be conducted.

The Influence of Gender, Age, and Body Mass Index on Arch Height and Arch Stiffness

Arch structure and arch function play an important role in maintaining balance, bearing body weight, and absorbing ground reaction forces. However, arch structure and arch function are known to vary extensively and may be affected by factors such as gender, age, and obesity. Therefore, the purpose of this study was to examine the influence of gender, age, and body mass index (BMI) on arch height and arch stiffness. A total of 173 participants (aged 57.60 ± 11.19 years, mean BMI 25.12 ± 3.93 kg/m²) participated in this cross-sectional study. A 3-dimensional laser scanner was used to measure foot structure information in each subject, from which arch height and arch stiffness were calculated. The results showed that women had low-arched feet compared with men (p = .001), and no arch stiffness difference was found. Older individuals tended to have a stiffer arch than middle-aged and younger individuals (p < .05), and no arch height difference was found. BMI had an impact on arch height (p < .05) but not arch stiffness. Finally, a weak positive relationship existed between arch height and arch stiffness (r = 0.32, p < .01). The findings suggest that gender, age, and obesity have a certain impact on arch structure and arch stiffness. Figuring out the relationship between these factors and arch structure may be helpful in understanding the bases of foot deformity and foot dysfunction.

Evaluation of the paediatric foot using footprints and foot posture index: A cross-sectional study

AIM

Footprints have long been used as proxy measures of foot morphology, yet there is little consensus regarding footprints versus measures of foot posture, which address foot anatomy directly. Foot posture in children can be a confusing clinical presentation, with previous studies both supporting and refuting the relationship between childhood obesity and flat feet. The aim of this study was to determine the relationship between footprints and foot posture in children.

METHODS

A total of 316 school children (153 boys, 163 girls) from Spain, aged 6-9 years, were assessed for both footprint (Clarke's angle (CA)), by Tecniwork Pedrograph Plate, and foot posture (foot posture index (FPI)) measures, with participants barefoot, in a relaxed standing position, on a 50-cm elevated platform.

RESULTS

A negative correlation was found between FPI and footprints (CA) (rho = -0.505 left, P < 0.001) and by gender (rho = -0.457 for the left foot in girls, P < 0.001; rho = -0.548 for the left foot in boys, P < 0.001). The children with pes cavus according to the CA (73.3%) had normal feet according to FPI, and the children with severe pes planus according to the CA (78.98%) had pronated feet according to the FPI. A χ² test showed these results to be statistically significant (P > 0.001).

CONCLUSIONS

An inverse relationship between CA and FPI was identified, that is, the greater the FPI, the smaller the CA, but not all pronated foot are planus feet and not all cavus feet are supinated feet. Footprints may overestimate and misguide paediatric foot posture concerns.

Foot posture development in children aged 5 to11 years: A three-year prospective study

BACKGROUND

The paediatric flatfoot is a common presentation but it is unclear whether the condition will resolve on its own as the child gets older or whether treatment is required. Therefore, the study objective was to evaluate paediatric foot posture, and anthropometry, in children at two time points, three years apart.

MATERIAL AND METHODS

A sample of 1032 healthy children (505 boys, 527 girls; aged 5-11 years) was recruited for foot posture index (FPI) and anthropometry assessment (weight, height and body mass index, BMI). Assessment was repeated when the children were aged 8 years to 14 years. Paired t-tests, Anova, frequency tables and a multiple regressions were conducted.

RESULTS

Initially, approximately 70% had a neutral FPI range, 20% pronated, 3% highly pronated, and 4% supinated. Initial mean FPI was 3.6 ± 2.8, being higher in boys 3.7 ± 2.8 than in girls 3.4 ± 2.7 (p = 0.034). All FPI categories changed over time, with supinated and neutral FPI increased by 19.5% and 4.7% respectively. In contrast, pronated and highly pronated FPI reduced by 10.6% and 55.6% respectively. Regression showed only 1% FPI change was explained by increased height. FPI scores were significantly reduced after three years (3.57 to 3.33; p < 0.001).

CONCLUSION

Children's foot posture shifts toward neutral as age increases. There is minimal relationship with weight, height or BMI. Appreciation of developing foot posture could reduce over diagnosis and unnecessary treatment of paediatric flatfeet.

Comprehensive biomechanical characterization of feet in USMA cadets: Comparison across race, gender, arch flexibility, and foot types

Lower extremity musculoskeletal injuries are common, complex, and costly problems. Literature supports associations between static foot structure and dynamic foot function, as well as between overuse injury and demographic characteristics. Previous studies failed to provide a comprehensive biomechanical foot characteristics of at-risk military personnel. In this study, foot structure, function, and arch height flexibility (AHF) were objectively measured in 1090 incoming cadets (16.3% female, mean age of 18.5years and BMI of 24.5kg/m²) of the United States Military Academy at the start of their training. A Generalized Linear Model with an identity link function was used to examine the effects of race, gender, foot types, and AHF while accounting for potential dependence in bilateral data. Planus and flexible feet independently demonstrated over-pronation, as measured by reduced Center of Pressure Excursion Index (CPEI). When comparing across race, Black participants showed a significantly lower arch height index (AHI), a larger malleolar valgus index (MVI), and a higher prevalence of pes planus (91.7% versus 73.3% overall). However, Asian participants with flexible arches, rather than Black with low arch, displayed over-pronation in gait. Females showed no significant difference in standing AHI and MVI but demonstrated a significantly greater AHF and a reduced CPEI than male participants. This was the first large scale investigation that comprehensively characterized biomechanical foot in a cohort of young at-risk individuals with lower limb musculoskeletal injuries. Long-term goal is to examine the relationship between these biomechanical features and injuries, ultimately to develop effective preventive measures.

Concurrent validity of an automated algorithm for computing the center of pressure excursion index (CPEI)

Center of Pressure Excursion Index (CPEI), a parameter computed from the distribution of plantar pressures during stance phase of barefoot walking, has been used to assess dynamic foot function. The original custom program developed to calculate CPEI required the oversight of a user who could manually correct for certain exceptions to the computational rules. A new fully automatic program has been developed to calculate CPEI with an algorithm that accounts for these exceptions. The purpose of this paper is to compare resulting CPEI values computed by these two programs on plantar pressure data from both asymptomatic and pathologic subjects. If comparable, the new program offers significant benefits-reduced potential for variability due to rater discretion and faster CPEI calculation. CPEI values were calculated from barefoot plantar pressure distributions during comfortable paced walking on 61 healthy asymptomatic adults, 19 diabetic adults with moderate hallux valgus, and 13 adults with mild hallux valgus. Right foot data for each subject was analyzed with linear regression and a Bland-Altman plot. The automated algorithm yielded CPEI values that were linearly related to the original program (R²=0.99; P<0.001). Bland-Altman analysis demonstrated a difference of 0.55% between CPEI computation methods. Results of this analysis suggest that the new automated algorithm may be used to calculate CPEI on both healthy and pathologic feet.

The Relationship Between Arch Height and Arch FlexibilityA Proposed Arch Flexibility Classification System for the Description of Multidimensional Foot Structure

BACKGROUND

The correlation between arch structure and injury may be related to the fact that foot structure influences foot function. Foot structure is often defined by arch height, although arch flexibility may be just as important to form a more complete description. We propose an arch flexibility classification system, analogous to arch height classification, and then use the classification system to examine the relationship between arch flexibility and arch height.

METHODS

Arch height index was calculated in 1,124 incoming military cadets, of whom 1,056 had usable data. By measuring arch height during both sitting and standing, a measurement of arch flexibility could also be calculated. These values were used to create five arch flexibility categories: very stiff, stiff, neutral, flexible, and very flexible. The distribution of arch flexibility types among arch height categories was statistically compared.

RESULTS

The goodness of fit test showed a disproportionate number of each arch flexibility type in each of the arch height categories (P < .01). The largest proportion of cavus feet was very stiff and the smallest proportion was very flexible. Conversely, the largest proportion of planus feet was very flexible and the smallest proportion was very stiff.

CONCLUSIONS

The results of this research support the common belief that cavus feet tend to be very stiff and planus feet tend to be very flexible.

Association of arch height with ankle muscle strength and physical performance in adult men

Differences in arch height may have a certain impact on lower extremity muscle strength and physical performance. However, there is little evidence from investigation of the possible correlation of arch height with ankle muscle strength and physical performance measures. Sixty-seven participants took part in this study. Arch height index (AHI) was assessed and categorized using a 3-dimension foot scanner. Ankle muscle strength was measured employing a dynamometer. Physical performance measures including agility, force and proprioception were randomly tested. Compared to the medium AHI, the high AHI had lower plantarflexion and inversion peak torque. The high AHI also had lower peak torque per body weight value for plantarflexion and inversion at 120°/s (P = 0.026 and 0.006, respectively), and dorsiflexion at 30°/s (P = 0.042). No significant ankle muscle strength difference was observed between the low and medium AHI. Additionally, AHI was negatively correlated with eversion and inversion peak torque at 120°/s, and negatively associated with plantarflexion, eversion and inversion peak torque per body weight at both 30°/s and 120°/s (r ranged from -0.26 to -0.36, P values < 0.050). However, no significant relationship was found between arch height and physical performance measures. The results showed that high arches had lower ankle muscle strength while low arches exhibited greater ankle muscle strength. Arch height was negatively associated with ankle muscle strength but not related to physical performance. We suggest that the lower arch with greater ankle muscle strength may be an adaptation to weight support and shock absorption.

Can static foot posture measurements predict regional plantar surface area?

BACKGROUND

The intent of this study was to determine if the use of a single or combination of static foot posture measurements can be used to predict rearfoot, midfoot, and forefoot plantar surface area in individuals with pronated or normal foot types.

METHODS

Twelve foot measurements were collected on 52 individuals (mean age 25.8 years) with the change in midfoot width used to place subjects in a pronated or normal foot mobility group. Dynamic plantar contact area was collected during walking with a pressure sensor platform. The 12 measures were entered into a stepwise regression analysis to determine the optimal set of measures associated with regional plantar surface area.

RESULTS

A two variable model was found to describe the relationship between the foot measurements and forefoot plantar contact area (r(2)=0.79, p<0.0001). A four variable model was found to describe the relationship between the foot measurements and midfoot plantar contact area (r(2)=0.85, p<0.0001) in those individuals with a 1.26cm or greater change in midfoot width.

CONCLUSIONS

The results indicate that clinicians can use a combination of simple, reliable and time efficient foot measures to explain 79% and 85% of the plantar surface area in the forefoot and midfoot, respectively.

The association of foot arch posture and prior history of shoulder or elbow surgery in elite-level baseball pitchers

STUDY DESIGN

Case-control.

OBJECTIVES

The specific aim of this study was to examine the association between abnormal foot arch postures and a history of shoulder or elbow surgery in baseball pitchers.

BACKGROUND

Pitching a baseball generates forces throughout the musculoskeletal structures of the upper and lower limbs. Structures such as the longitudinal arch of the foot are adaptable to stresses over time. Repeated pitching-related stresses may contribute to acquiring abnormal foot arch postures. Inversely, congenitally abnormal foot arch posture may lead to altered stresses of the upper limb during pitching.

METHODS

A convenience sample of 77 pitchers was recruited from a Division I university team and a professional baseball franchise. Subjects who had a history of shoulder or elbow surgery to the pitching arm were classified as cases. Subjects who met the criteria for classification of pes planus or pes cavus based on longitudinal arch angle were classified as having abnormal foot arch posture. Odds ratios were calculated to examine the association between abnormal foot arch posture and pitching-arm injury requiring surgery.

RESULTS

Twenty-three subjects were classified as cases. The odds of being a case were 3.4 (95% confidence interval: 1.2, 9.6; P = .02) times greater for subjects with abnormal foot arch posture and 2.9 (95% confidence interval: 1.0, 8.1; P = .04) times greater for subjects with abnormal foot posture on the lunge leg.

CONCLUSION

Abnormal foot arch posture and a surgical history in the pitching shoulder or elbow may be associated. Because the foot and its arches are adaptable and change over time, the pathomechanics of this association should be further explored.

Flexible pes planus in adolescents: body mass index, body height, and gender--an epidemiological study

BACKGROUND

Most studies on the prevalence of flexible pes planus (FPP) have been conducted in pediatric populations and older adults. There is limited comparable information on these parameters for the adolescent age group. The purpose of this study was to report the prevalence of FPP and its association with body mass index (BMI), body height, and gender among healthy and fit adolescents.

METHODS

The data for this study were derived from a medical database containing records of 17-year-old males and females before their recruitment into mandatory military service. Information on the disability codes associated with FPP according to the Regulations of Medical Fitness Determination was retrieved. Logistic regression models were used to assess the association between BMI, body height, and gender to various grades of FPP severity.

RESULTS

The study cohort included 825 964 adolescents (467 412 males and 358 552 females). The prevalence was 12.4% for mild FPP and 3.8% for severe FPP among the males and 9.3% and 2.4%, respectively, for the females. An increased BMI was associated with FPP in both males (overweight: odds ratio [OR] 1.385, confidence interval [CI] 1.352-1.419, P < .001; obese: OR 1.765, CI 1.718-1.813, P < .001) and females (overweight: OR 1.408, CI 1.365-1.620, P < .001; obese: OR 1.549, CI 1.481-1.620, P < .001). Body height was associated with a decreased risk of FPP when the highest height quintile was compared with the lowest height quintile in both males (OR 0.782, CI 0.762-0.802, P < .001) and females (OR 0.730, CI 0.707-0.754, P < .001) for all FPP severity grades.

CONCLUSIONS

There was a greater prevalence of FPP among males compared with females in a general healthy adolescent age group. FPP was associated with increased BMI and shorter body height for all grades of FPP severity.

LEVEL OF EVIDENCE

Level II, diagnostic study.

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

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.

Foot Type Biomechanics Part 2: are structure and anthropometrics related to function?

BACKGROUND

Many foot pathologies are associated with specific foot types. If foot structure and function are related, measurement of either could assist with differential diagnosis of pedal pathologies.

HYPOTHESIS

Biomechanical measures of foot structure and function are related in asymptomatic healthy individuals.

METHODS

Sixty-one healthy subjects' left feet were stratified into cavus (n=12), rectus (n=27) and planus (n=22) foot types. Foot structure was assessed by malleolar valgus index, arch height index, and arch height flexibility. Anthropometrics (height and weight), age, and walking speed were measured. Foot function was assessed by center of pressure excursion index, peak plantar pressure, maximum force, and gait pattern parameters. Foot structure and anthropometric variables were entered into stepwise linear regression models to identify predictors of function.

RESULTS

Measures of foot structure and anthropometrics explained 10-37% of the model variance (adjusted R(2)) for gait pattern parameters. When walking speed was included, the adjusted R(2) increased to 45-77% but foot structure was no longer a factor. Foot structure and anthropometrics predicted 7-47% of the model variance for plantar pressure and 16-64% for maximum force parameters. All multivariate models were significant (p<0.05), supporting acceptance of the hypothesis.

DISCUSSION AND CONCLUSION

Foot structure and function are related in asymptomatic healthy individuals. The structural parameters employed are basic measurements that do not require ionizing radiation and could be used in a clinical setting. Further research is needed to identify additional predictive parameters (plantar soft tissue characteristics, skeletal alignment, and neuromuscular control) and to include individuals with pathology.

The effect of arch height on kinematic coupling during walking

The purpose of the current study was to assess kinematic coupling within the foot in individuals across a range of arch heights. Seventeen subjects participated in this study. Weight-bearing lateral radiographs were used to measure the arch height, defined as angle between the 1st metatarsal and the calcaneus. A kinematic model including the 1st metatarsal, lateral forefoot, calcaneus and tibia was used to assess foot kinematics during walking. Four coupling ratios were calculated: calcaneus frontal to forefoot transverse plane motion (Calcaneal EV/Forefoot AB), calcaneus frontal to transverse plane motion (Calcaneus EV/AB), forefoot sagittal to transverse plane motion (Forefoot DF/AB), and 1st metatarsal sagittal to transverse plane motion (1st Metatarsal DF/AB). Pearson product moment correlations were used to assess the relationship between arch height and coupling ratios. Mean (SD) radiographic arch angles of 129.8 (12.1) degrees with a range from 114 to 153 were noted, underscoring the range of arch heights in this cohort. Arch height explained approximately 3%, 38%, 12% and 1% of the variance in Calcaneal EV/Forefoot AB, Calcaneus EV/AB, Forefoot DF/AB and 1st Metatarsal DF/AB respectively. Calcaneal EV/Forefoot AB, Calcaneus EV/AB, Forefoot DF/AB and 1st Metatarsal DF/AB coupling ratios of 1.84 ± 0.80, 0.56 ± 0.35, 0.96 ± 0.27 and 0.43 ± 0.21 were noted, consistent with the twisted foot plate model, windlass mechanism and midtarsal locking mechanisms. Arch height had a small and modest relationship with kinematic coupling ratios during walking.

Can foot anthropometric measurements predict dynamic plantar surface contact area?

BACKGROUND

Previous studies have suggested that increased plantar surface area, associated with pes planus, is a risk factor for the development of lower extremity overuse injuries. The intent of this study was to determine if a single or combination of foot anthropometric measures could be used to predict plantar surface area.

METHODS

Six foot measurements were collected on 155 subjects (97 females, 58 males, mean age 24.5 +/- 3.5 years). The measurements as well as one ratio were entered into a stepwise regression analysis to determine the optimal set of measurements associated with total plantar contact area either including or excluding the toe region. The predicted values were used to calculate plantar surface area and were compared to the actual values obtained dynamically using a pressure sensor platform.

RESULTS

A three variable model was found to describe the relationship between the foot measures/ratio and total plantar contact area (R2 = 0.77, p < 0.0001)). A three variable model was also found to describe the relationship between the foot measures/ratio and plantar contact area minus the toe region (R2 = 0.76, p < 0.0001).

CONCLUSION

The results of this study indicate that the clinician can use a combination of simple, reliable, and time efficient foot anthropometric measurements to explain over 75% of the plantar surface contact area, either including or excluding the toe region.

Differences in plantar loading between flat and normal feet during different athletic tasks

The purpose of this study was to determine if foot type (flat or normal) resulted in loading differences during four sport-specific tasks (cross-cut, side-cut, shuttle run, and landing from a simulated lay-up). Twenty-two healthy subjects (12 normal feet and 10 flat feet) completed five trials in each condition, while in-shoe pressure data was collected at 50 Hz. Contact area, maximum force, and the force time integral were analyzed under the entire foot and in eight-foot regions. Foot type was determined by examining navicular height, arch angle, rearfoot angle, and a clinical score. A series of independent sample t-tests were used to determine statistical differences (alpha<0.05). During the cross-cut, flat feet demonstrated an increase in medial midfoot contact area. During the side-cut, flat feet demonstrated an increase in contact area, force time integral and maximum force in both the medial and lateral midfoot. During the shuttle run, flat feet demonstrated an increase in force time integral in the lateral midfoot and increases in maximum force in both the medial and lateral midfoot. During the landing task, flat feet demonstrated an increase in maximum force in the medial midfoot. However, flat feet demonstrate a decrease in middle forefoot maximum force. All results were statistically significant (p<0.05). Therefore, individuals with a normal foot could be at a lower risk for medial and lateral midfoot injuries such as metatarsal stress fractures, indicating that foot type should be assessed when determining an individual's risk for metatarsal stress fractures.

Correlation between static foot type measurements and clinical assessments

BACKGROUND

An accurate and consistent differentiation of foot type is needed to assess appropriate treatments and to examine potential risk factors for acute and overuse injuries.

MATERIALS AND METHODS

One hundred forty-seven members of the American Orthopaedic Foot and Ankle Society were asked to complete a questionnaire related to clinical assessments of foot type and to examine 30 photographs of healthy feet taken on the mirrored foot photo box (MFPB). Responders were asked to categorize each image into one of five categories (pes planus, low arch, normal, high arch, and pes cavus). Different static measurements were obtained from each image. Pearson correlations were calculated between the static foot measures and the clinical grade. Significantly correlated parameters were analyzed via regression analysis.

RESULTS

Clinical assessment was reported to be the most important tool in defining foot type (69.9%) followed by standing radiographs and foot print measurements. Clinicians stated that arch height (56.2%) was the most used physical characteristic, while the lateral talo-first metatarsal angle (64.4%) was the most used radiographic assessment. Foot measurements were correlated with the clinical grade (r = 0.511 to 0.780). Regression analysis revealed that rearfoot angle, foot print index and truncated arch index were significant predictors of clinically defined foot type. Rearfoot angle accounted for 78% of the variance in clinically assessed foot type.

CONCLUSION

The results of this study indicate the need to measure multiple parameters to assess foot type. However, if only one parameter can be collected, it appears that rearfoot angle explains the majority of variance in the clinically assessed foot type.

Flat-footedness is not a disadvantage for athletic performance in children aged 11 to 15 years

OBJECTIVE

Because the controversy about the relation of foot morphology and foot function is still present, we find it surprising that there are no studies published dealing with motor skills and athletic performance in flat-footed school children. Our aim in this study was to determine if there is an association between the degree of foot flatness and several motor skills that are necessary for sport performance.

METHODS

The feet of 218 children aged 11 to 15 years were scanned, and the arch index was determined. The value of the arch index was corrected for the influence of age, and then the entire sample was categorized into 4 groups according to the flatness of their feet. The children were tested for eccentric-concentric contraction and hopping on a Kistler force platform, speed-coordination polygon (Newtest system), balance (3 tests), toe flexion (textile crunching), tiptoe standing angle, and repetitive leg movements. Altogether, 17 measures of athletic performance were measured.

RESULTS

No significant correlations between the arch height and 17 motor skills were found. Categorizing the sample into 4 groups did not reveal any differences between the groups in athletic performance. Also, several multivariate analysis of variance sets of multiple independent variables referring to a particular motor ability were not found to be significant. The differences were not found even after comparing only the 2 extreme groups, meaning children with very low and children with very high arches.

CONCLUSIONS

No disadvantages in sport performance originating from flat-footedness were confirmed. Children with flat and children with "normal" feet were equally successful at accomplishing all motor tests; thus, we suggest that there is no need for treatment of flexible flat feet with the sole purpose of improving athletic performance, as traditionally advised by many.