Dynamic navicular motion measured using a stretch sensor is different between walking and running, and between over-ground and treadmill conditions

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.

RF. Fatigue Testing of Wearable Sensing Technologies: Issues and Opportunities

Standards for the fatigue testing of wearable sensing technologies are lacking. The majority of published fatigue tests for wearable sensors are performed on proof-of-concept stretch sensors fabricated from a variety of materials. Due to their flexibility and stretchability, polymers are often used in the fabrication of wearable sensors. Other materials, including textiles, carbon nanotubes, graphene, and conductive metals or inks, may be used in conjunction with polymers to fabricate wearable sensors. Depending on the combination of the materials used, the fatigue behaviors of wearable sensors can vary. Additionally, fatigue testing methodologies for the sensors also vary, with most tests focusing only on the low-cycle fatigue (LCF) regime, and few sensors are cycled until failure or runout are achieved. Fatigue life predictions of wearable sensors are also lacking. These issues make direct comparisons of wearable sensors difficult. To facilitate direct comparisons of wearable sensors and to move proof-of-concept sensors from "bench to bedside", fatigue testing standards should be established. Further, both high-cycle fatigue (HCF) and failure data are needed to determine the appropriateness in the use, modification, development, and validation of fatigue life prediction models and to further the understanding of how cracks initiate and propagate in wearable sensing technologies.

Is Motorized Treadmill Running Biomechanically Comparable to Overground Running? A Systematic Review and Meta-Analysis of Cross-Over Studies

BACKGROUND

Treadmills are often used in research, clinical practice, and training. Biomechanical investigations comparing treadmill and overground running report inconsistent findings.

OBJECTIVE

This study aimed at comparing biomechanical outcomes between motorized treadmill and overground running.

METHODS

Four databases were searched until June 2019. Crossover design studies comparing lower limb biomechanics during non-inclined, non-cushioned, quasi-constant-velocity motorized treadmill running with overground running in healthy humans (18-65 years) and written in English were included. Meta-analyses and meta-regressions were performed where possible.

RESULTS

33 studies (n = 494 participants) were included. Most outcomes did not differ between running conditions. However, during treadmill running, sagittal foot-ground angle at footstrike (mean difference (MD) - 9.8° [95% confidence interval: - 13.1 to - 6.6]; low GRADE evidence), knee flexion range of motion from footstrike to peak during stance (MD 6.3° [4.5 to 8.2]; low), vertical displacement center of mass/pelvis (MD - 1.5 cm [- 2.7 to - 0.8]; low), and peak propulsive force (MD - 0.04 body weights [- 0.06 to - 0.02]; very low) were lower, while contact time (MD 5.0 ms [0.5 to 9.5]; low), knee flexion at footstrike (MD - 2.3° [- 3.6 to - 1.1]; low), and ankle sagittal plane internal joint moment (MD - 0.4 Nm/kg [- 0.7 to - 0.2]; low) were longer/higher, when pooled across overground surfaces. Conflicting findings were reported for amplitude of muscle activity.

CONCLUSIONS

Spatiotemporal, kinematic, kinetic, muscle activity, and muscle-tendon outcome measures are largely comparable between motorized treadmill and overground running. Considerations should, however, particularly be given to sagittal plane kinematic differences at footstrike when extrapolating treadmill running biomechanics to overground running. Protocol registration CRD42018083906 (PROSPERO International Prospective Register of Systematic Reviews).

Cranio-caudal and medio-lateral navicular translation are representative surrogate measures of foot function in asymptomatic adults during walking

Introduction

The translation of the navicular bone is thought to be a representative surrogate measure to assess foot pronation and hence foot function; however, it is not known how it is related to multi-segment foot kinematics.

Methods

Cranio-caudal (NCC) and medio-lateral (NML) navicular translation and multi-segment foot kinematics from the Oxford Foot Model (OFM) were simultaneously assessed during the stance phase of walking in 20 healthy adults. Relationships to forefoot to hindfoot (FFtoHF), hindfoot to tibia (HFtoTBA) and global hindfoot (HFL) motion were explored by cross-correlations at zero phase shift.

Results

FFtoHF sagittal, transversal and frontal plane angles showed median cross correlations of -0.95, 0.82 and 0.53 with NCC and of 0.78, -0.81 and -0.90 with NML. HFtoTBA transversal and frontal plane angles had correlations of 0.15 and 0.74 with NCC and of -0.38 and -0.83 with NML. The HFL frontal plane angle showed correlations of 0.41 and -0.44 with NCC and NML, respectively.

Discussion

The strongest relationships were found between FFtoHF sagittal plane angles and NCC and between FFtoHF frontal plane angles and NML. However, cranio-caudal and medio-lateral navicular translation seem to be reasonable surrogates for the triplanar motion between the fore- and hindfoot. The medial longitudinal arch dropped and bulged medially, while the forefoot dorsiflexed, abducted and everted with respect to the hindfoot and vice-versa. The lower cross-correlation coefficients between the rear foot parameters and NCC/NML indicated no distinct relationships between rearfoot frontal plane and midfoot kinematics. The validity of rearfoot parameters, like Achilles tendon or Calcaneal angle, to assess midfoot function must be therefore questioned. The study could also not confirm a systematic relationship between midfoot kinematics and the internal/external rotation between the hindfoot and the tibia. The measurement of navicular translation is suggested as an alternative to more complex multi-segment foot models to assess foot function.

The influence of gait and speed on the dynamic navicular drop - A cross sectional study on healthy subjects

INTRODUCTION

Variations of gait speed influence kinematic variables that may have an effect on dynamic foot deformation. The influence of gait speed on the navicular drop has not yet been investigated.

METHODS

The navicular drop was evaluated in static and dynamic conditions using a 3D-motion capture system. The dynamic navicular drop was evaluated on a treadmill while walking and running at three different speeds. A repeated measures ANOVA and post-hoc tests were conducted to evaluate the differences in dynamic navicular drop, corresponding unloaded navicular height at foot strike and loaded navicular height during stance.

RESULTS

Higher walking speed led to a significant decrease in navicular height at foot strike and a subsequent decrease of dynamic navicular drop (p=0.006). Across increasing running speeds, minimum navicular height was significantly decreased which in consequence led to an increased dynamic navicular drop (p=0.015). For walking and running at the same speed, there was a large effect of gait style with an increase of dynamic navicular drop by 3.5mm (p<0.001) during running.

DISCUSSION

The change of gait from walking to running at the same speed had a large effect on dynamic navicular drop. The values of navicular height at foot strike and minimum navicular height during stance should be taken into account for the interpretation of dynamic navicular drop measures. Static and dynamic navicular drop measures differ substantially.

A minimal markerset for three-dimensional foot function assessment: measuring navicular drop and drift under dynamic conditions

Background

The validity of predicting foot pronation occurring mainly at the midfoot by surrogate measures from the rearfoot, like eversion excursion, is limited. The dynamic navicular mobility in terms of vertical navicular drop (dNDrop) and medial navicular drift (dNDrift) may be regarded as meaningful clinical indicators to represent overall foot function. This study aimed to develop a minimal approach to measure the two parameters and to examine their intra- and interday reliability during walking.

Methods

The minimal markerset uses markers at the lateral and medial caput of the 1^st and 5^th metatarsals, respectively, at the dorsal calcaneus and at the tuberosity of the navicular bone. Dynamic navicular drop and drift were assessed with three-dimensional motion capture in 21 healthy individuals using a single-examiner test-retest study design.

Results

Intra- and interday repeatability were 1.1 mm (ICC₂₁ 0.97) and 2.3 mm (ICC₂₁ 0.87) for dynamic navicular drop and 1.5 mm (ICC₂₁ 0.96) and 5.3 mm (ICC₂₁ 0.46) for dynamic navicular drift. The contribution of instrumental errors was estimated to 0.25 mm for dynamic navicular drop and 0.86 mm for dynamic navicular drift.

Conclusions

Interday reliability was generally worse than intraday reliability primary due to day-to-day variations in movement patterns and the contribution of instrumental errors was below 23% for dynamic navicular drop but reached 57% for dynamic navicular drift. The minimal markerset allows to simply transfer the known concepts of navicular drop and drift from quasi-static clinical test conditions to functional tasks, which is recommended to more closely relate assessments to the functional behavior of the foot.

Electronic supplementary material

The online version of this article (10.1186/s13047-018-0257-2) contains supplementary material, which is available to authorized users.

Epidemiology of Navicular Injury at the NFL Combine and Their Impact on an Athlete's Prospective NFL Career

Background:

Navicular injuries can result in persistent pain, posttraumatic osteoarthritis, and diminished performance and function.

Purpose:

To determine the epidemiology of navicular fracture in players participating in the National Football League (NFL) Scouting Combine and evaluate the impact of a navicular injury on the NFL draft position and NFL game play compared with matched controls.

Study Design:

Cohort study; Level of evidence, 3.

Methods:

Data were collected on players who previously sustained a navicular injury and participated in the NFL Combine between 2009 and 2015. The epidemiology of navicular injury was determined through an evaluation of the number of injuries, surgeries, and collegiate games missed as well as the position played, a physical examination, the surgical technique, and imaging findings. Players with a previous navicular injury (2009-2013) were compared with a set of matched controls. NFL performance outcomes included the draft position, career length ≥2 years, and number of games played and started within the first 2 years.

Results:

Between 2009 and 2015, 14 of 2285 (0.6%) players were identified as having sustained a navicular injury. A total of 11 of 14 (79%) athletes had sustained an overt navicular fracture, while 3 of 14 (21%) were diagnosed with stress reactions on magnetic resonance imaging. Eight patients who sustained a navicular fracture underwent surgery. There was evidence of ipsilateral talonavicular arthritis in 75% of players with a navicular fracture versus only 60% in the uninjured foot (odds ratio, 1.3; P = .04). Fifty-seven percent of players with navicular injury (72.7% of fractures) were undrafted versus 30.9% in the control group (P = .001). Overall, 28.6% of players with navicular fracture played ≥2 years in the NFL compared with 69.6% in the control group (P = .02).

Conclusion:

A previous navicular fracture results in a greater risk of developing posttraumatic osteoarthritis. Although only a low prevalence of navicular injury in prospective NFL players was noted, players with these injuries had a greater probability of not being drafted and not competing in at least 2 NFL seasons when compared with matched controls without an injury history to the NFL Combine.

Relationship between patient-reported outcome measures (PROM) and three measures of foot-ankle alignment in patients with metatarsal head pain: a cross-sectional study

Background

The aim of the present study is to establish the relationship between foot–ankle patient-reported outcome measures (PROM) and three measures of foot–ankle alignment (MoFAA) in patients with metatarsal head pain.

Methods

A cross-sectional study where 206 patients completed three PROMs and a clinician recorded three MoFAA bilaterally (three times each). A reliability analysis of the MoFAA, a correlation analysis (between MoFAA and PROM) and regression analysis (dependent variable: PROM; independent variables: MoFAA) were performed.

Results

Pearson’s coefficient changed in each PROM used, ranging from 0.243 (AAOS-FAM_{ShoeComfortScale}–FVA_Right) to 0.807 (FFI_Index–first MTPJE_right). Regression indices (R²-corrected) ranged between 0.117 (AAOS-FAM_{ShoeComfortScale}) and 0.701 (FFI_Index).

Conclusions

The MoFAA correlated between moderately to strongly with the foot–ankle PROM selected. The level of correlation between MoFAA and PROM was higher when patients with metatarsal head pain were asked about foot health status, pain and function; however, the correlation was poor when the patient was asked about shoe aspects. In addition, the MoFAA variable that achieved the highest correlation value was the first metatarsophalangeal joint extension. The results obtained in this study could be used in future studies to develop tools for assessing and monitoring patients with metatarsal head pain.

Kinematic analysis of ankle stiffness in subjects with and without flat foot

BACKGROUND

Although the magnitude of ankle motion is influenced by joint congruence and ligament elasticity, there is a lack of understanding on ankle stiffness between subjects with and without flat foot.

OBJECTIVE

This study investigated a quantified ankle stiffness difference between subjects with and without flat foot.

METHODS

There were forty-five age- and gender-matched subjects who participated in the study. Each subject was seated upright with the tested foot held firmly onto a footplate that was attached to a torque sensor by the joint-driving device.

RESULTS

The flat foot group (mean ± standard deviation) demonstrated increased stiffness during ankle dorsiflexion (0.37 ± 0.16 for flat foot group, 0.28 ± 0.10 for control group; t=-2.11, p=0.04). However, there was no significant group difference during plantar flexion (0.35 ± 0.15 for flat foot group, 0.33 ± 0.07 for control group; t=0.64, p=0.06).

CONCLUSION

The results of this study indicated that the flat foot group demonstrated increased ankle stiffness during dorsiflexion regardless of demographic factors. This study highlights the need for kinematic analyses and joint stiffness measures during ankle dorsiflexion in subjects with flat foot.