Reliability of navicular displacement measurement as a clinical indicator of foot posture

Reliability and correlation of weight-bearing cone beam CT and Foot Posture Index (FPI) for measurements of foot posture: a test-retest study

OBJECTIVE

To assess test-retest reliability and correlation of weight-bearing (WB) and non-weight-bearing (NWB) cone beam CT (CBCT) foot measurements and Foot Posture Index (FPI) MATERIALS AND METHODS: Twenty healthy participants (age 43.11±11.36, 15 males, 5 females) were CBCT-scanned in February 2019 on two separate days on one foot in both WB and NWB positions. Three radiology observers measured the navicular bone position. Plantar (ΔNAVplantar) and medial navicular displacements (ΔNAVmedial) were calculated as a measure of foot posture changes under loading. FPI was assessed by two rheumatologists on the same two days. FPI is a clinical measurement of foot posture with 3 rearfoot and 3 midfoot/forefoot scores. Test-retest reproducibility was determined for all measurements. CBCT was correlated to FPI total and subscores.

RESULTS

Intra- and interobserver reliabilities for navicular position and FPI were excellent (intraclass correlation coefficient (ICC) .875-.997). In particular, intraobserver (ICC .0.967-1.000) and interobserver reliabilities (ICC .946-.997) were found for CBCT navicular height and medial position. Interobserver reliability of ΔNAVplantar was excellent (ICC .926 (.812; .971); MDC 2.22), whereas the ΔNAVmedial was fair-good (ICC .452 (.385; .783); MDC 2.42 mm). Using all observers' measurements, we could calculate mean ΔNAVplantar (4.25±2.08 mm) and ΔNAVmedial (1.55±0.83 mm). We demonstrated a small day-day difference in ΔNAVplantar (0.64 ±1.13mm; p<.05), but not for ΔNAVmedial (0.04 ±1.13mm; p=n.s.). Correlation of WBCT (WB navicular height - ΔNAVmedial) with total clinical FPI scores and FPI subscores, respectively, showed high correlation (ρ: -.706; ρ: -.721).

CONCLUSION

CBCT and FPI are reliable measurements of foot posture, with a high correlation between the two measurements.

Efficacy of Personalized Foot Orthoses in Children with Flexible Flat Foot: Protocol for a Randomized Controlled Trial

Pediatric flat foot (PFF) is a very frequent entity and a common concern for parents and health professionals. There is no established definition, diagnostic method, or clear treatment approach. There are multiple conservative and surgical treatments, the implantation of foot orthoses (FO) being the most used treatment. The evidence supporting FO is very thin. It is not clearly known what the effect of these is, nor when it is convenient to recommend them. The main objective of this protocol is to design a randomized controlled trial to determine if personalized FO, together with a specific exercise regimen, produce the same or better results regarding the signs and symptoms of PFF, compared to only specific exercises. In order to respond to the stated objectives, we have proposed a randomized controlled clinical trial, in which we intend to evaluate the efficacy of FO together with strengthening exercises, compared to a control group in which placebos will be implanted as FO treatment along with the same exercises as the experimental group. For this, four measurements will be taken throughout 18 months (pre-treatment, two during treatment and finally another post-treatment measurement). The combination of FO plus exercise is expected to improve the signs and symptoms (if present) of PFF compared to exercise alone and the placebo FO group. In addition, it is expected that in both conditions the biomechanics of the foot will improve compared to the initial measurements.

Translation, Cross-Cultural Adaptation, and Validation of the Foot Posture Index (FPI-6)-Italian Version

Since foot posture is one of the main predictors of lower limb musculoskeletal injuries, it is crucial to use appropriate tools to define the foot's posture. The Foot Posture Index is, therefore, a reliable method to measure foot posture and is widely known and used in clinics and research. This study aimed to translate the Foot Posture Index 6 (FPI6) into Italian and to assess its psychometric properties. Translation and cross-cultural adaptation were obtained using a popular guideline. Two examinators assessed 68 subjects, and data were collected to test intra/inter-rater reliability, internal consistency and cross-cultural validity. The Italian version of FPI6 showed excellent inter- and intra-rater reliability (ICC 0.96 and 0.97), and Cronbach's alpha coefficient was 0.9, thus showing excellent internal consistency. The FPI-6 version has proved to be reliable in terms of inter- and intra-rater reliability and can, therefore, be used in clinical practice and scientific research.

The interrelationship between three-dimensional foot mobility and bodyweight bearing

[Purpose] To clarify the three-dimensional nature of foot mobility and its interrelationships within the foot due to bodyweight bearing. [Participants and Methods] Data regarding left foot mobility due to body weight bearing were collected from 31 healthy adults. Foot shape differences while sitting and standing, and their interrelationship were examined. The same examiner reapplied the landmark stickers when misaligned during measurement position changes. [Results] The foot length, heel width, forefoot width, hallux valgus angle, and calcaneus eversion angle were significantly larger in the standing than in sitting position. The digitus minimus varus angle was significantly smaller in the standing than in sitting position. The medial and lateral malleoli, navicular, and dorsum of the foot were displaced medially and inferiorly; the other indices, except for the midfoot, were displaced anteriorly. The interrelationships within the foot showed a positive correlation between the calcaneus eversion angle and the medial displacement of the medial and lateral malleoli, navicular, and dorsum of the foot points. There was a negative correlation between the calcaneus eversion angle and inferior displacement of the medial malleolus, navicular, and dorsum of the foot. [Conclusion] The intra-foot coordination relationship in response to bodyweight bearing was clarified.

Low-dye taping may enhance physical performance and muscle activation in basketball players with overpronated feet

BACKGROUND

Low-dye taping (LTD) is widely used by athletes and medical practitioners but the research regarding its impacts on athletic performance is lacking. This study investigated the effects of using low-dye taping on plyometric performance and muscle activities in recreational basketball players with overpronated feet.

METHODS

Twelve collegiate males with at least three years basketball training experience and navicular drop (ND) value ≥10 mm performed the navicular drop, drop jump and countermovement jump tests. Surface electromyography of selected lower limb muscles were observed during bilateral free squat. All tests in non-taped (NT) and taped (TAP) conditions were counterbalanced using repeated crossover study design. Paired t-test with an alpha level of 0.05 and non-clinical magnitude-based decision (MBD) with standardized effects were used to analyze data.

RESULTS

Contact time and reactive strength index (RSI) in the TAP condition were significantly shorter (p = 0.041) and higher (p<0.01) than the NT condition respectively. No significant difference in CMJ performance between NT and TAP was observed. MBD demonstrated clear effects on both ND (standardized effect: -1.54±0.24), flight time (standardized effect: 0.24±0.30), contact time (standardized effect: -0.27±0.21), RSI (standardized effect: 0.69±0.35) and eccentric activities of inferior gluteus maximus (standardized effect: 0.23±0.35), gluteus medius (standardized effect: 0.26±0.29) and tibialis anterior (standardized effect: 0.22±0.06).

CONCLUSIONS

LDT is effective in correcting overpronated feet by increasing ND height. Meanwhile, it provides a small increase in RSI and gluteal muscle activity during the eccentric (down) phase of the bilateral squat, and without affecting CMJ performance. Conditioning coaches or therapists may use LDT to enhance gluteal activation for reducing injury occurrence and reactive strength performance in drop jump tasks.

The relationship between foot and ankle joint flexibility measures and barefoot plantar pressures in healthy older adults: a cross-sectional study

BACKGROUND

Restriction in foot and ankle joint range of motion, such as an ankle equinus, has been associated with increased plantar pressure and its complications. However, previous research is limited by its scope of measures and study populations. The aim of this study was to investigate the relationship between foot and ankle joint range of motion on barefoot plantar pressures during walking in healthy older adults.

METHODS

This cross-sectional study recruited 49 older adults. Participants underwent measures of foot (first metatarsophalangeal dorsiflexion range of motion, and navicular drop and drift) and ankle joint range of motion, foot posture, body mass index, and plantar pressure during barefoot walking. Spearman Rank Order Correlations were used to explore the relationship between foot and ankle measures, body mass index, and plantar pressure, with significant correlations explored in a hierarchical regression analysis. A Mann-Whitney U test was performed to compare plantar pressure values between those with and without ankle equinus per region of the foot.

RESULTS

Mean (SD) age and BMI were 72.4 years (5.2) and 29.8 kg/m² (5.9) respectively. A total of 32 of the 49 participants (65%) identified as female sex. Mean (SD) ankle joint range of motion was 32.7 (6.4) degrees with 17/49 (34.7%) participants classified as having an ankle equinus (defined as < 30 degrees of ankle joint dorsiflexion range of motion). We found that an ankle equinus predicted a statistically significant amount of peak forefoot plantar pressure (p = 0.03). Participants with an ankle equinus displayed significantly higher forefoot peak pressure 677.8 kPa (589.9 to 810.4) compared to those with no equinus 565.58 kPa (447.3 to 651.2), p = 0.02. A statistically significant correlation was found between body mass index and midfoot peak pressure (p < 0.01) and pressure-time integral (p < 0.01). No other significant correlations were found.

CONCLUSION

Clinicians should consider screening for an ankle equinus and body mass index as a simple way to identify which healthy older adults may be at risk of pressure-related complications in the mid- and forefoot.

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.

Reliability and Repeatability of Pressure Center Analysis with Low-Dye Taping Using Force Platform Podiatry Sensors in Feet with Excessive Pronation

BACKGROUND

The analysis of the center of pressure (COP) is a method used to assess the foot function, but its reliability and repeatability have not been evaluated. COP can be altered by diverse conditions, like an excessive foot pronation. Low-Dye taping is commonly used for the treatment of symptoms related to an excessive pronation. To date, no study has evaluated the effects of the Low-Dye taping on COP and the duration of its effects. Thus, the main purpose of this manuscript was to assess the reliability and repeatability of the percentage of center of pressure locus area (%CLA) in feet with an excessive pronation, and secondarily, to assess that the Low-Dye taping modifies the %CLA during the immediate 48 h.

METHODS

An observational study of the reliability and repeatability of the %CLA variable with the Low-Dye taping in feet with excessive pronation was carried out. We used the EPS-Platform to evaluate the results of the variable in 6 conditions in a first session to evaluate the reliability of the results. We compared the results of the first session with the results in a second session to evaluate the repeatability of the results. We also carried out an ANOVA test to evaluate the changes that the taping produced in the variable between without taping with the rest of the 6 conditions.

RESULTS

For the %CLA, we observed a reliability greater than 0.80, measured by the interclass ratio index, both in the first session before taping, and in the second session before taping, thus being a repeatability variable. In the following times, with taping, at 10 min with tape, at 20 min with tape, at 24 h with tape and at 48 h with tape; an interclass ratio coefficient (ICC) higher than 0.80 was again obtained, thus being a reliable variable in all measurements made. The Low-Dye taping did not change %CLA from the time the tape was put in until 48 h (p-value = 1.000).

CONCLUSIONS

The %CLA variable, in feet with excessive pronation, proved to be a reliable variable in all the measurements obtained before putting on the tape and during the following 48 h with the tape, and a repeatable variable. The Low-Dye taping did not change the %CLA from the time the tape was put in until 48 h.

Reliability of Different Clinical Techniques for Assessing Foot Posture

OBJECTIVE

The aim was to determine the interrater and intrarater reliability of navicular drop (NDP), navicular drift (NDT), and the Foot Posture Index-6 (FPI-6), and test-retest reliability of the static arch index (SAI) and dynamic arch index (DAI).

METHODS

Sixty healthy individuals were assessed for intrarater and test-retest reliability. From 60 participants, 30 individuals were assessed for interrater reliability. A digital caliper was used to measure NDP and NDT. Electronic pedography was used to calculate SAI and DAI. The FPI-6 was also performed. All assessments were performed on the dominant foot. The NDP, NDT, SAI, and DAI were repeated 3 times. The NDP and NDT were analyzed separately using both first measurement and the average, but the SAI and DAI were analyzed using only the average. The NDP, NDT, and FPI-6 were conducted by 2 raters to determine interrater reliability and were repeated by a single rater after 5 days from initial assessment to determine intrarater reliability. The SAI and DAI were also repeated after 5 days to determine test-retest reliability.

RESULTS

Intrarater intraclass correlation coefficients (ICCs) were 0.934 and 0.970 for NDP, 0.724 and 0.850 for NDT, and 0.945 for FPI. Interrater ICCs were 0.712 and 0.811 for NDP, 0.592 and 0.797 for NDT, and 0.575 for FPI. Test-retest ICCs of the SAI and DAI were 0.850 and 0.876, respectively.

CONCLUSION

Navicular drop is relatively more reliable than other traditional techniques. Also, the FPI-6 has excellent intrarater reliability, but only moderate interrater reliability. The results can provide clinicians and researchers with a reliable way to implement foot posture assessment.

Feasibility Study of a Rapid Evaluate and Adjust Device (READ) for Custom Foot Orthoses Prescription

OBJECTIVE

Custom foot orthoses (CFOs) are typically used for the prevention and cure of lower extremity injuries (LEIs). Typically, CFOs are designed and prescribed based on iterative loops including: (1) follow-up loops between the patient and the physician, and (2) design feedback loops between the physician and the fabricator. The current prescription methodology has some deficiencies, i.e. excessive time to satisfactory treatment, and low repeatability in custom fabrication because of missing alignment, soft tissue considerations, and subjective feedback. There are significant opportunities to develop a new CFOs prescription procedure which can improve accuracy prior to the fabrication process by reducing time through minimizing iterations.

METHODS

First, a novel "rapid evaluate and adjust device" (READ) prescription methodology is proposed for CFO design by combining the follow-up loops with design feedback loop. To support the idea of the READ prescription method a novel 3D ergonomic measurement system (3DEMS) is developed. The 3DEMS is designed for the following key targets to: (1) improve the communication between the patient/physician and the fabricator, (2) reduce time to satisfactory treatment, (3) improve repeatability by considering the alignment and the soft tissue deformations, (4) archive digitally with minimal data, (5) reduce the system complexity, and (6) validate with plantar pressure measurements (i.e. Novel Pedar^®). The design process of the 3DEMS involved the following steps: (1) 3D data collection at the desired loading, (2) nested optimization to determine optimal segment design, and (3) system fabrication considering alignment and feedback control.

RESULTS

The results show that the READ prescription method with 3DEMS can be used to recreate the medial longitudinal arch for a range of arch height indices (AHI) by using a minimal number of parameters i.e. 6 parameters, and significant increases in mean peak pressure are observed between optimized and barefoot or flat segments.

CONCLUSION

This study establishes that the proposed READ prescription method with the 3DEMS may be used for CFOs prescription due to better communication between individuals in the follow-up and design loops, less time for satisfactory treatment, improved repeatability, archivable data, and low system complexity.

SIGNIFICANCE

The developed system may be used as measurement systems for CFOs, and in the future the proposed 3DEMS may prove highly important for the measurement of CFOs for flat feet.

Balance in focus: a simple observational scale to monitor the effect of exercises on static balance in case of childhood flexible flat foot

[Purpose] Childhood flexible flat foot is the most common lower limb deformity. Observational evaluation of the underlying elements of reactive balance during static positions is an accepted tool besides the timed measures. We aim to assess the effects of combined balance training on the foot function and to test the usefulness of our observational static balance score. [Participants and Methods] A total of 19 healthy primary school students with flexible flat foot deformity volunteered for the study. We evaluated the foot’s dynamic properties and static postural stability before and after a 20-week combined balance training. On the basis of the observational findings, the time vs. quality observational static balance score was developed. All data were subjected to Wilcoxon’s test and Friedman’s ANOVA to compare the effects of the training on foot trajectory and observational static balance score. [Results] Better strength and endurance in the foot extensors and improved foot function were noted after the training. Using our observational static balance score, the quality of the balance performance remarkably changed. [Conclusion] The quality domain of our new scale seems to be a useful tool in daily clinical practice and a more sensitive measure in eyes-closed situations.

Evaluating the Medial Longitudinal Arch of the Foot: Correlations, Reliability, and Accuracy in People With a Low Arch

BACKGROUND

The medial longitudinal arch of the foot is a variable structure, and a decrease in its height could affect several functions and increase the risk of injuries in the lower limbs. There are many different techniques for evaluating it.

OBJECTIVE

The objective of this study was to evaluate the correlations of the Navicular Drop Test, several footprint parameters, and the Foot Posture Index-6 in people with a low medial longitudinal arch. Intrarater reliability and interrater reliability were also estimated.

DESIGN

This was a repeated-measures, observational descriptive study.

METHODS

Seventy-one participants (53.5% women; mean age = 24.13 years; SD = 3.41) were included. All of the parameters were collected from the dominant foot. The correlation coefficients were calculated. The reliability was also calculated using the intraclass correlation coefficient, 95% CI, and kappa coefficient.

RESULTS

Statistically significant correlations were obtained between the Navicular Drop Test and the footprint parameters, with r absolute values ranging from 0.722 to 0.788. The Navicular Drop Test and the Foot Posture Index-6 showed an excellent correlation (Spearman correlation coefficient = 0.8), and good correlations (Spearman correlation coefficient = |0.663-0.703|) were obtained between the footprint parameters and the Foot Posture Index-6. Excellent intrarater reliability and interrater reliability were obtained for all of the parameters.

LIMITATIONS

Radiographic parameters, the gold standard for evaluating the medial longitudinal arch height, were not used. In addition, the results of this research cannot be generalized to people with normal and high medial longitudinal arches.

CONCLUSIONS

In participants with a low medial longitudinal arch, the Navicular Drop Test showed significant correlations with footprint parameters; correlations were good for the arch angle and Chippaux-Smirnak Index, and excellent for the Staheli Index. The Foot Posture Index-6 showed an excellent correlation with the Navicular Drop Test and a good correlation with the footprint parameters evaluated. All of the parameters showed high reliability.

Medial Longitudinal Arch: Accuracy, Reliability, and Correlation Between Navicular Drop Test and Footprint Parameters

OBJECTIVE

The purpose of this study was to evaluate the correlation among the navicular drop test, the arch angle, the Staheli index and the Chippaux-Smirak index. The reliability and the correlation among the footprint parameters were also estimated.

METHODS

A cross-sectional study (n = 86; 59.3% women; 27.8 years, standard deviation: 4.8 years) was carried out. The navicular drop test was evaluated and footprint parameters using a plantar pressure platform were recorded in the dominant foot. Pearson correlation coefficients, intraclass correlation coefficient, standard error of measurement, and minimum detectable change were calculated.

RESULTS

Both intrarater and interrater reliability were excellent for all the parameters evaluated (intraclass correlation coefficients > 0.880). Statistically significant correlations existed between the navicular drop test and footprints parameters (arch angle = 0,643; Staheli index = 0.633; Chippaux-Smirak index = 0.614). The footprint parameters had excellent correlation with each other (0.838-0.881). The navicular drop test and the footprint parameters studied were reproducible and thus had excellent reliability.

CONCLUSION

The correlations obtained between the navicular drop test and the footprint parameters evaluated were good. The navicular drop test appears to be a reproducible, valid, and simple test for evaluating medial longitudinal arch height, having fewer disadvantages than using footprint parameters.

Application of Zebris dynamometric platform and Arch Index in assessment of the longitudinal arch of the foot

BACKGROUND

Assessment of the foot arch is an important element of posture examination. In clinical practice, different methods are used. Reliability and repeatability of the techniques raises many doubts.

OBJECTIVE

Development and verification of our own, automated diagnostic algorithm for evaluation of the longitudinal arch of the foot with the use of the Zebris FDM-S dynamometric platform.

METHODS

This paper presents selected footprints assessment methods and Zebris dynamometric platform to assess the longitudinal arch of the foot.

RESULTS

The results were compared to standard plantography examination. The outcomes show high correlation of the investigated parameters methods used. The ambiguity of classification criteria of foot arch was observed.

CONCLUSIONS

1/Examination confirmed strong linear correlation between the Arch Index results obtained during examinations on a stabilometric platform and plantography examination. 2/The proposed algorithm for AI evaluation using the Zebris FDM-S dynamometric platform enables simultaneous analysis of stabilometric and pedobarometric variables as well classifying the type of disorder arch longitudinal arch of the foot. 3/Qualitative analysis of the arch, based on plantography results and the Arch Index, shows inconsistency in results obtained with different methods. 4/The obtained results show further necessity to conduct more studies to develop methods of standardization of foot arch assessment.

The relationship between arch height and foot length: Implications for size grading

OBJECTIVE

Medial longitudinal Arch Height is synonymous with classifying foot type and conversely foot function. Detailed knowledge of foot anthropometry is essential in the development of ergonomically sound footwear. Current Footwear design incorporates a direct proportionate scaling of instep dimensions with those of foot length. The objective of this paper is to investigate if a direct proportional relationship exists between human arch height parameters and foot length in subjects with normal foot posture.

METHOD

A healthy convenience sample of 62 volunteers was recruited to participate in this observational study. All subjects were screened for normal foot health and posture. Each subject's foot dimensions were scanned and measured using a 3D Foot Scanner. From this foot length and arch height parameters were obtained. Normalised ratios of arch height with respect to foot length were also calculated. The arch height parameters and the normalised arch ratios were used interchangeably as the dependent variables with the foot length parameters used as the independent variable for Simple Linear Regression and Correlation.

RESULTS

Analysis of foot length measures demonstrated poor correlation with all arch height parameters.

CONCLUSION

No significant relationships between arch height and foot length were found. The predictive value of the relationship was found to be poor. This holds significant implications for the current method of proportionate scaling of footwear in terms of fit and function to the midfoot region for a normative population.

Can positional MRI predict dynamic changes in the medial plantar arch? An exploratory pilot study

BACKGROUND

Positional MRI (pMRI) allows for three-dimensional visual assessment of navicular position. In this exploratory pilot study pMRI was validated against a stretch sensor device, which measures movement of the medial plantar arch. We hypothesized that a combined pMRI measure incorporating both vertical and medial displacement of the navicular bone induced by loading would be correlated with corresponding stretch sensor measurements.

METHODS

10 voluntary participants were included in the study. Both pMRI and subsequent stretch sensor measurements were performed in a) supine, b) standing and c) standing position with addition of 10 % body weight during static loading of the foot. Stretch sensor measurements were also performed during barefoot walking.

RESULTS

The total change in navicular position measured by pMRI was 10.3 mm (CI: 7.0 to 13.5 mm). No further displacement occurred when adding 10 % bodyweight (mean difference: 0.7 mm (CI: -0.7 to 2.0 mm), P = 0.29). The total navicular displacement correlated with stretch sensor measurement under static loading conditions (Spearman's rho = 0.66, P = 0.04) but not with measurements during walking (Spearman's rho = 0.58, P = 0.08).

CONCLUSIONS

Total navicular bone displacements determined by pMRI showed concurrent validity with stretch sensor measurements but only so under static loading conditions. Although assessment of total navicular displacement by combining concomitant vertical and medial navicular bone movements would appear advantageous compared to monoplanar measurement the combined measure did not seem to predict dynamic changes of the medial foot arch during walking, which are among several possible factors depending on different walking patterns.

Establishing normative foot posture index values for the paediatric population: a cross-sectional study

BACKGROUND

The Foot Posture Index (FPI) is an observational tool designed to measure the position of the foot. Its reliability is well established, and it provides normative reference values for the general population. However, this is not so for the paediatric population. The aim of this study is to determine FPI reference values in childhood, taking into account age and gender.

METHODS

This cross-sectional study included 1,762 school children (863 boys and 899 girls) aged 6-11 years, from Málaga, Granada and Plasencia (Spain). In every case, FPI measurements were obtained for both feet by two experienced podiatrists. A descriptive analysis was then conducted and the percentiles of the variables determined, with a significance level of P < 0.05.

RESULTS

The consolidated FPI results for the sample population produced mean values of 3.74 (SD 2.93) points for the right foot and 3.83 (SD 2.92) for the left. The 50th percentile was 4 points for both genders and for both feet, except for the right foot among the girls, which was slightly lower, at 3 points. The 85th percentile, which is considered to represent the boundary between the normal and the pronated foot among children, was 6 points, uniformly among the subjects.

CONCLUSIONS

As a normative FPI value for the paediatric population, we recommend the 50th percentile, i.e. 4 points, for children, of both genders, aged 6 years. This value progressively falls with age, to 3 FPI points for children aged 11 years. The 85th percentile for the pronated foot and the 4th percentile for the supinated foot can be considered the pathological boundary.

Navicular bone position determined by positional MRI: a reproducibility study

OBJECTIVE

To examine intraobserver, interobserver and between-day reproducibility of positional MRI for evaluation of navicular bone height (NVH) and medial navicular position (MNP).

MATERIALS AND METHODS

Positional MRI (pMRI) of the foot was performed on ten healthy participants (0.25 T G-scanner). Scanning was performed in supine and standing position, respectively. Two radiologists evaluated the images in a blinded manner. Reliability and agreement were assessed by calculation of intraclass correlation coefficient (ICC) and 95 % limits of agreement as a percentage of the mean (LOA%).

RESULTS

Intraobserver and interobserver reliability was "substantial" in both supine and standing position (ICC 0.86-0.98) and showed good agreement (LOA% 4.9-14.7 %). Between-day reliability of navicular height and medial navicular position in standing position remained substantial (ICC 0.85-0.92) with adequate agreement (LOA% 8.3-19.8 %). In supine position between-day reliability was "moderate" for NVH (ICC 0.72) and "slight" for MNP (ICC 0.39). Agreement remained adequate between-days for MNP in supine position (LOA% 17.7 %), but it was less than adequate for NVH in supine position (LOA% 24.2 %).

CONCLUSION

Navicular height and medial navicular position can be measured by pMRI in a very reproducible manner within and between observers. Increased measurement variation is observed between-days in supine position, which may be due to small positional differences or other unknown biomechanical factors.

Muscle-Activation Onset Times With Shoes and Foot Orthoses in Participants With Chronic Ankle Instability

CONTEXT

Participants with chronic ankle instability (CAI) use an altered neuromuscular strategy to shift weight from double-legged to single-legged stance. Shoes and foot orthoses may influence these muscle-activation patterns.

OBJECTIVE

To evaluate the influence of shoes and foot orthoses on onset times of lower extremity muscle activity in participants with CAI during the transition from double-legged to single-legged stance.

DESIGN

Cross-sectional study.

SETTING

Musculoskeletal laboratory.

PATIENTS OR OTHER PARTICIPANTS

A total of 15 people (9 men, 6 women; age = 21.8 ± 3.0 years, height = 177.7 ± 9.6 cm, mass = 72.0 ± 14.6 kg) who had CAI and wore foot orthoses were recruited.

INTERVENTION(S)

A transition task from double-legged to single-legged stance was performed with eyes open and with eyes closed. Both limbs were tested in 4 experimental conditions: (1) barefoot (BF), (2) shoes only, (3) shoes with standard foot orthoses, and (4) shoes with custom foot orthoses (SCFO).

MAIN OUTCOME MEASURE(S)

The onset of activity of 9 lower extremity muscles was recorded using surface electromyography and a single force plate.

RESULTS

Based on a full-factorial (condition, region, limb, vision) linear model for repeated measures, we found a condition effect (F(3,91.8) = 9.39, P < .001). Differences among experimental conditions did not depend on limb or vision condition. Based on a 2-way (condition, muscle) linear model within each region (ankle, knee, hip), earlier muscle-activation onset times were observed in the SCFO than in the BF condition for the peroneus longus (P < .001), tibialis anterior (P = .003), vastus medialis obliquus (P = .04), and vastus lateralis (P = .005). Furthermore, the peroneus longus was activated earlier in the shoes-only (P = .02) and shoes-with-standard-foot-orthoses (P = .03) conditions than in the BF condition. No differences were observed for the hip muscles.

CONCLUSIONS

Earlier onset of muscle activity was most apparent in the SCFO condition for ankle and knee muscles but not for hip muscles during the transition from double-legged to single-legged stance. These findings might help clinicians understand how shoes and foot orthoses can influence neuromuscular control in participants with CAI.

Motion analysis to track navicular displacements in the pediatric foot: relationship with foot posture, body mass index, and flexibility

BACKGROUND

Increased navicular drop (NDro) and navicular drift (NDri) are associated with musculoskeletal pathology in adults. The aim of this study was to investigate navicular motion in children, with respect to foot posture, and identify altered patterns of motion that demonstrate midfoot dysfunction. Navicular motion in different activities was evaluated as well as the role of flexibility and body mass index (BMI).

METHODS

Twenty-five children with flatfeet and 26 with neutral feet (age range, 8-15) underwent gait analysis using a 12-camera Vicon MX system (Vicon, UK). Navicular motion indices were calculated from marker coordinates. Student t tests and Pearson's correlation coefficient (R) were used to investigate navicular motion differences between groups. The relationship between NDRo, NDRi, and their dynamic counterparts was also assessed.

RESULTS

Normalized NDri (NNDri) and normalized NDro (NNDro) correlated strongly in neutral feet (R = 0.56, P = .003) but not in flatfeet (R = 0.18, P > .05). Flatfeet demonstrated reduced NNDri compared to neutral footed children (0.7 vs 1.6, P = .007). No difference was observed in NNDro between groups. Standard and dynamic measures of NDri and NDRo were highly correlated. Navicular motion correlated poorly with BMI and flexibility.

CONCLUSION

Motion of the navicular in the transverse and the sagittal plane is important when investigating foot function. Uncoupling of this motion in flatfeet may indicate impaired midfoot function. Reduced navicular medial translation in flatfeet may indicate altered alignment of the talonavicular joint.

CLINICAL RELEVANCE

The measurement of dynamic navicular motion indices did not add information about dynamic foot function compared to measurement of static indices.

Reproducibility of and sex differences in common orthopaedic ankle and foot tests in runners

Background

For future etiologic cohort studies in runners it is important to identify whether (hyper)pronation of the foot, decreased ankle joint dorsiflexion (AJD) and the degree of the extension of the first Metatarsophalangeal joint (MTP1) are risk factors for running injuries and to determine possible sex differences.

These parameters are frequently determined with the navicular drop test (NDT) Stance and Single Limb-Stance, the Ankle Joint Dorsiflexion-test, and the extension MTP1-test in a healthy population. The aim of this clinimetric study was to determine the reproducibility of these three orthopaedic tests in runners, using minimal equipment in order to make them applicable in large cohort studies. Furthermore, we aimed to determine possible sex differences of these tests.

Methods

The three orthopaedic tests were administered by two sports physiotherapists in a group of 42 (22 male and 20 female) recreational runners. The intra-class correlation (ICC) for interrater and intrarater reliability and the standard error of measurement (SEM) were calculated. Bland and Altman plots were used to determine the 95% limits of agreements (LOAs). Furthermore, the difference between female and male runners was determined.

Results

The ICC’s of the NDT were in the range of 0.37 to 0.45, with a SEM in the range of 2.5 to 5 mm. The AJD-test had an ICC of 0.88 and 0.86 (SEM 2.4° and 8.7°), with a 95% LOA of -6.0° to 6.3° and -5.3° to 7.9°, and the MTP1-test had an ICC of 0.42 and 0.62 (SEM 34.4° and 9.9°), with a 95% LOA of -30.9° to 20.7° and -20° to 17.8° for the interrater and intrarater reproducibility, respectively.

Females had a significantly (p < 0.05) lower navicular drop score and higher range of motion in extension of the MTP1, but no sex differences were found for ankle dorsiflexion (p ≥ 0.05).

Conclusion

The reproducibility for the AJD test in runners is good, whereas that of the NDT and extension MTP1 was moderate or low. We found a difference in NDT and MTP1 mobility between female and male runners, however this needs to be established in a larger study with more reliable test procedures.

The relationship among foot posture, core and lower extremity muscle function, and postural stability

CONTEXT

Identification of impaired balance as a risk factor for lower extremity injury regardless of injury history has led to subsequent investigation of variables that may adversely affect balance in healthy individuals.

OBJECTIVES

To investigate the relationship among core and lower extremity muscle function, foot posture, and balance.

DESIGN

Descriptive laboratory study.

SETTING

Musculoskeletal injury biomechanics laboratory.

PATIENTS OR OTHER PARTICIPANTS

A total of 108 individuals (40 men, 68 women; age = 22.8 ± 4.7 years, height = 168.5 ± 10.4 cm, mass = 69.9 ± 13.3 kg) participated in the study.

MAIN OUTCOME MEASURE(S)

Core endurance was assessed during 1 time-to-failure trial, and isometric hip and ankle strength were assessed using a handheld dynamometer and isokinetic dynamometer, respectively. Foot structure was quantified using the digital photographic measurement method. Single-limb-stance time to boundary was assessed using a force plate during an eyes-closed condition. Hierarchical multiple regression analyses were performed to predict balance using lower extremity strength, foot posture, and core endurance.

RESULTS

Foot posture (β = -0.22, P = .03) and ankle-inversion strength (β = -0.29, P = .006) predicted mediolateral balance. Increasing arch posture and ankle-inversion strength were associated with decreased mediolateral single-limb-stance balance.

CONCLUSIONS

Increasing arch height was associated with decreased mediolateral control of single-limb stance. The relationship between time to boundary and injury risk, however, has not been explored. Therefore, the relationship between increasing arch height and injury due to postural instability cannot be determined from this study. If authors of future prospective studies identify a relationship between decreased time to boundary and increased injury risk, foot structure may be an important variable to assess during preparticipation physical examinations. The relationship between increasing ankle-inversion strength and decreased balance may require additional study to further elucidate the relationship between ankle strength and balance.

Reliability and concurrent validity of a novel method allowing for in-shoe measurement of navicular drop

Background

Increased navicular drop is associated with increased risk of lower extremity overuse injuries and foot orthoses are often prescribed to reduce navicular drop. For laboratory studies, transparent shoes may be used to monitor the effect of orthoses but no clinically feasible methods exist. We have developed a stretch-sensor that allows for in-shoe measurement of navicular drop but the reliability and validity is unknown. The purpose of this study was to investigate: 1) the reliability of the stretch-sensor for measuring navicular drop, and 2) the concurrent validity of the stretch-sensor compared to the static navicular drop test.

Methods

Intra- and inter-rater reliability was tested on 27 participants walking on a treadmill on two separate days. The stretch-sensor was positioned 20 mm posterior to the tip of the medial malleolus and 20 mm posterior to the navicular tuberosity. The participants walked six minutes on the treadmill before navicular drop was measured. Reliability was quantified by the Intraclass Correlation Coefficient (ICC 2.1) and agreement was quantified by Limits of Agreement (LOA). To assess concurrent validity, static navicular drop was measured with the stretch-sensor and compared with static navicular drop measured with a ruler on 27 new participants. Linear regression was used to measure concurrent validity.

Results

The reliability of the stretch-sensor was acceptable for barefoot measurement (intra- and inter-rater ICC: 0.76-0.84) but lower for in-shoe measurement (ICC: 0.65). There was a significant association between static navicular drop measured with the stretch-sensor compared with a ruler (r = 0.745, p < 0.001).

Conclusion

This study suggests that the stretch-sensor has acceptable reliability for dynamic barefoot measurement of navicular drop. Furthermore, the stretch-sensor shows concurrent validity compared with the static navicular drop test as performed by Brody. This new simple method may hold promise for both clinical assessment and research but more work is needed before the method can be recommended.

The effects of prolonged running on foot posture: a repeated measures study of half marathon runners using the foot posture index and navicular height

Background

Different foot postures are associated with alterations in foot function, kinetics and the subsequent occurrence of injury. Little is known about changes in foot posture following prolonged weightbearing exercise. This study aimed to identify changes in foot posture after running a half marathon.

Methods

Foot posture was measured using the Foot Posture Index (FPI-6) and navicular height in thirty volunteer participants before and after running a half marathon. FPI-6 scores were converted to Rasch logit values and means compared for these and navicular height using an ANOVA.

Results

There was a 5 mm drop in navicular height in both feet when measured after the half marathon (P < 0.05). The FPI-6 showed a side x time interaction with an increase in score indicating a more ‘pronated’ position in the left foot of + 2 [Rasch value + 1.7] but no change in the right foot (+ 0.4 [+ 0.76]) following the half marathon.

Conclusion

The apparent differences between the FPI-6 and navicular height on the right foot may be because the FPI-6 takes soft tissue contour changes into consideration whilst the navicular height focuses on skeletal changes. The changes in foot posture towards a more pronated position may have implications for foot function, and therefore risk of injury; shoe fit and comfort and also the effect of therapeutic orthoses worn during prolonged running.

Exercise therapy and custom-made insoles are effective in patients with excessive pronation and chronic foot pain--a randomized controlled trial

BACKGROUND

Excessive foot pronation is a causal mechanisms described in relation to injuries of the lower extremities. Evidence to support an effective treatment is insufficient.

OBJECTIVE

To investigate the effect of exercise and custom-made insoles to patients with excessive pronation and chronic pain conditions in the foot at short and long term follow-up.

METHODS

Single blinded Randomized Controlled Trial with 80 subjects randomized: (1) Standard Intervention, (2) Insole, (3) Exercise, and (4) Insole+Exercise. Exercise - 12 week supervised program. Insoles - individually molded and posted. Pain was measured during walking, resting and running. Static and dynamic foot postures were measured as calcaneal angle, navicular drift, drop and height.

RESULTS

The average duration of foot pain was 7.3 years. There was a significant pain reduction during walking within all groups at 4 and 12 months follow-up. No differences were seen between groups in any of the pain parameters. Weak correlations between changes in pain and foot postures were observed at baseline and one-year follow-up.

CONCLUSION

A significant pain reduction was seen in all groups, none of the treatment modalities seem to be superior with the number of patients included. Compliance in the standard intervention group was a concern at 12 months.

Normal genetic variation of the human foot: Part 2: Population variance, epigenetic mechanisms, and developmental constraint in function

Congenital deformities of the foot have been reported to correlate with regulatory epigenetic mechanisms that are also responsible for the timing and sequencing of developmental growth of the lower limb. Developmental variance of normal morphologic features has also been shown to vary between populations despite the retention of human foot characteristics. The molecular evidence for genetically controlled expressions of common evolved physical features is highly suggestive of regulatory control mechanisms that act together with developmental constraints to homogenize the retained functional characteristics of the foot. Genetic variance in morphologic features and functional plasticity when linked to morphometric change during gait may prove influential in clarifying kinematic and kinetic relationships.

Visual categorisation of the arch index: a simplified measure of foot posture in older people

BACKGROUND

Foot posture is considered to be an important component of musculoskeletal assessment in clinical practice and research. However, many measurement approaches are not suitable for routine use as they are time-consuming or require specialised equipment and/or clinical expertise. The objective of this study was therefore to develop and evaluate a simple visual tool for foot posture assessment based on the Arch Index (AI) that could be used in clinical and research settings.

METHODS

Fully weightbearing footprints from 602 people aged 62 to 96 years were obtained using a carbon paper imprint material, and cut-off AI scores dividing participants into three categories (high, normal and low) were determined using the central limit theorem (i.e. normal = +/- 1 standard deviation from the mean). A visual tool was then created using representative examples for the boundaries of each category. Two examiners were then asked to use the tool to independently grade the footprints of 60 participants (20 for each of the three categories, randomly presented), and then repeat the process two weeks later. Inter- and intra-tester reliability was determined using Spearman's rho, percentage agreement and weighted kappa statistics. The validity of the examiner's assessments was evaluated by comparing their categorisations to the actual AI score using Spearman's rho and analysis of variance (ANOVA), and to the actual AI category using percentage agreement, Spearman's rho and weighted kappa.

RESULTS

Inter- and intra-tester reliability of the examiners was almost perfect (percentage agreement = 93 to 97%; Spearman's rho = 0.91 to 0.95, and weighted kappas = 0.85 to 0.93). Examiner's scores were strongly correlated with actual AI values (Spearman's rho = 0.91 to 0.94 and significant differences between all categories with ANOVA; p < 0.001) and AI categories (percentage agreement = 95 to 98%; Spearman's rho = 0.89 to 0.94, and weighted kappas = 0.87 to 0.94). There was a slight tendency for examiners to categorise participants as having higher arches than their AI scores indicated.

CONCLUSIONS

Foot posture can be quickly and reliably categorised as high, normal or low in older people using a simplified visual categorisation tool based on the AI.

Measuring medial longitudinal arch deformation during gait. A reliability study

Clinical evaluation of medial longitudinal arch deformation (MLAD) during walking gait is often estimated from static measures of e.g. navicular drop (ND) measured during quiet standing. The aim of the present study was to test the reliability of a new three-dimensional method of measuring the MLAD during gait and to compare this method with a static measure and a 2D dynamic method. Fifty-two feet (26 healthy male participants) were tested twice 4-9 days apart in a biomechanical gait analysis laboratory using a 3D three-marker foot model, a 2D video-based model for the measurement of MLAD during gait, and ND for measurements of MLAD during quiet standing. The 3D method showed the highest test-retest reliability among the measurements of MLAD. Furthermore, the ND showed only moderate correlation with both measurements of MLAD during gait. The new 3D method was found to be highly reliable and showed that ND obtained during quiet standing could not predict the MLAD during gait. The 3D method, or alternatively the 2D method, may be used in clinical settings as reliable methods for easy estimation of the foot longitudinal stability.

Variations in foot posture and mobility between individuals with patellofemoral pain and those in a control group

BACKGROUND

We sought to determine whether foot posture and foot mobility were increased in individuals with patellofemoral pain syndrome compared with individuals in a control group.

METHODS

A nested case-control design was used with two controls matched to each patient by sex and age (±1 year). Participants included 43 individuals with a history of unilateral or bilateral patellofemoral pain syndrome and 86 participants in a control group. Data collected included height, weight, and five different measures of foot height and width in weightbearing and nonweightbearing that have been previously shown to have high levels of reliability.

RESULTS

Individuals with patellofemoral pain syndrome were found to be four times more likely (odds ratio, 4.04; 95% confidence interval, 1.45-11.32) to have a larger-than-normal difference between nonweightbearing and weightbearing arch height compared with those in the control group. The mean values for difference in arch height and foot mobility magnitude were also statistically significant between the patient and control groups. Foot posture, as determined using the arch height ratio, was not significant between groups (odds ratio, 0.94; 95% confidence interval, 0.34-2.61).

CONCLUSIONS

Although foot posture may not be different between individuals with patellofemoral pain syndrome and controls, foot mobility assessed using difference in arch height and foot mobility magnitude is different between the two groups.

Relationships between clinical measures of static foot posture and plantar pressure during static standing and walking

BACKGROUND

Information is limited about the relationships between clinical measures of static foot posture and peak plantar pressures under the medial column of the foot. The purpose was to examine these relationships during static standing and walking.

METHODS

A single-group exploratory design using correlation and regression was used to determine relationships. Ninety-two healthy volunteers participated. Clinical measures of static foot posture including arch index, navicular drop and navicular drift were obtained during static standing. Peak plantar pressures under the hallux, medial forefoot, medial midfoot, and medial rearfoot were obtained during standing and walking.

FINDINGS

Static foot posture was related to peak plantar pressures during standing and walking, but the strengths of relationships ranged from poor to fair. During standing, navicular drop was correlated (P≤0.05) with hallux (r=0.29) and medial forefoot (r=-0.17) pressures, while arch index (r=-0.17) and navicular drift (r=0.25) were correlated (P≤0.05) with hallux pressure. During walking, arch index, navicular drop and navicular drift were correlated (P≤0.05) with hallux and medial forefoot pressures (r range -0.30 to 0.41), while arch index (r=-0.15) and navicular drop (r=0.16) were correlated (P≤0.05) with medial midfoot pressure. Regression models predicted (P≤0.05) hallux (R(2)=0.08) and medial midfoot (R(2)=0.05) pressures during standing, and hallux (R(2)=0.18), medial forefoot (R(2)=0.07), and medial rearfoot (R(2)=0.05) pressures during walking.

INTERPRETATION

In healthy participants, lower arch foot postures are associated with greater pressures under the hallux and medial mid-foot and lower pressures under the medial forefoot, but the strength of these relationships may be only poor to fair.

Sagittal plane blockage of the foot, ankle and hallux and foot alignment-prevalence and association with low back pain

INTRODUCTION

Some practitioners believe mechanical low back pain may be caused or aggravated by a stiff ankle, stiff great toe or flat feet. This study investigates subjects with and without mechanical low back pain and measures ankle and great toe range of motion and flattening of the medial longitudinal arch in both groups.

METHODS

The study was a blinded, 2-arm, non- randomized clinical study involving 100 subjects with chronic or recurrent mechanical low back pain (intervention group) and 104 subjects without chronic mechanical low back pain (control group) between the ages of 18 and 45. A blind assessor performed weight-bearing goniometry of the ankle and big toe and the navicular drop test on all subjects in both groups.

RESULTS

An independent t-test (inter-group) revealed a statistically significant decrease (p </= 0.05) in ankle dorsiflexion range of motion in individuals with chronic mechanical low back pain. The independent t-test suggested individuals with chronic mechanical low back pain have a significantly smaller navicular drop and higher arches (p < 0.05).

CONCLUSION

This study supports previous reports suggesting decreased ankle dorsiflexion may be a factor in chronic mechanical low-back pain. Further research and replication of this study is necessary before firm conclusions or recommendations can be made.

Radiographic evaluation of navicular position in the sagittal plane-correction following an extraosseous talotarsal stabilization procedure

The navicular drop in the sagittal plane on weight-bearing is a valid indicator of foot pronation. Dislocation of the talus on the tarsal mechanism results in hyperpronation, which can lead to excessive navicular drop. The purpose of the present study was to radiographically determine the efficacy of HyProCure(®) in realigning the navicular bone in hyperpronating feet. We hypothesized that following the placement of HyProCure(®), the navicular height would increase significantly compared to its preoperative value. Radiographs of 61 adult patients (86 feet) who received HyProCure(®) without adjunctive hindfoot or midfoot soft tissue or osseous procedures were analyzed. The distance of the navicular with respect to the cuboid was measured from the pre- and postoperative weight-bearing lateral radiographs. Additionally, we measured foot length to normalize the navicular to cuboid distance. The postoperative radiographs were taken at an average follow-up of 17 days. The mean preoperative true navicular to cuboid distance was 19 ± 6 mm as compared to a mean postoperative value of 24 ± 5 mm. The mean pre- and postoperative normalized navicular to cuboid distances were 0.098 ± 0.029 and 0.125 ± 0.027, respectively (± 1 SD). The postoperative increase in the true and normalized navicular to cuboid distance was statistically significant (p < .001). HyProCure(®) was effective in improving the anatomic alignment of the talonavicular joint by reducing excessive navicular drop. This indicates reduction of excessive abnormal pronation and stabilization of the medial column of the foot, which can also lead to reduction in the excessive forces placed on the supporting soft tissue structures.

Medial longitudinal arch deformation during walking and stair navigation while carrying loads

BACKGROUND

Understanding the biomechanics of the medial longitudinal arch (MLA) may provide insights into injury risk and prevention, as well as function of the arch-supporting structures. Our understanding of MLA deformation is currently limited to sit-to-stand, walking, and running.

MATERIAL AND METHODS

Three-dimensional deformation of the MLA of the right foot was characterized in 17 healthy participants during several simulated activities of daily living. MLA deformation was quantified by both changes in arch length and navicular displacement during the stance phase of three motions: walking, stair ascent, and stair descent. Three levels of load were also evaluated: no load, a front load (13.6 kg), and a backpack load (13.6 kg). Force platforms and an eight-camera motion capture system were used to collect relevant lower extremity kinetic and kinematic data.

RESULTS

Motion type had a significant (p < 0.05) effect on navicular displacement and arch length elongation with navicular displacement being greatest during stair descent, while the walking and stair descent conditions showed the greatest increase in arch length. External load did not significantly affect either of these two measures (p > 0.05).

CONCLUSION

Differences in the MLA deformation variables resulting from varied dynamic activities of daily living can be greater than those during walking and should be considered.

CLINICAL RELEVANCE

Detailing the mechanics of the MLA may aid in further understanding injuries associated with the MLA, and the results of the current study indicate that these mechanics change based on activity.

A digital photographic measurement method for quantifying foot posture: validity, reliability, and descriptive data

CONTEXT

Although abnormal foot posture long has been associated with lower extremity injury risk, the evidence is equivocal. Poor intertester reliability of traditional foot measures might contribute to the inconsistency.

OBJECTIVES

To investigate the validity and reliability of a digital photographic measurement method (DPMM) technology, the reliability of DPMM-quantified foot measures, and the concurrent validity of the DPMM with clinical-measurement methods (CMMs) and to report descriptive data for DPMM measures with moderate to high intratester and intertester reliability.

DESIGN

Descriptive laboratory study.

SETTING

Biomechanics research laboratory.

PATIENTS OR OTHER PARTICIPANTS

A total of 159 people participated in 3 groups. Twenty-eight people (11 men, 17 women; age  =  25 ± 5 years, height  =  1.71 ± 0.10 m, mass  =  77.6 ± 17.3 kg) were recruited for investigation of intratester and intertester reliability of the DPMM technology; 20 (10 men, 10 women; age  =  24 ± 2 years, height  =  1.71 ± 0.09 m, mass  =  76 ± 16 kg) for investigation of DPMM and CMM reliability and concurrent validity; and 111 (42 men, 69 women; age  =  22.8 ± 4.7 years, height  =  168.5 ± 10.4 cm, mass  =  69.8 ± 13.3 kg) for development of a descriptive data set of the DPMM foot measurements with moderate to high intratester and intertester reliabilities.

INTERVENTION(S)

The dimensions of 10 model rectangles and the 28 participants' feet were measured, and DPMM foot posture was measured in the 111 participants. Two clinicians assessed the DPMM and CMM foot measures of the 20 participants.

MAIN OUTCOME MEASURE(S)

Validity and reliability were evaluated using mean absolute and percentage errors and intraclass correlation coefficients. Descriptive data were computed from the DPMM foot posture measures.

RESULTS

The DPMM technology intratester and intertester reliability intraclass correlation coefficients were 1.0 for each tester and variable. Mean absolute errors were equal to or less than 0.2 mm for the bottom and right-side variables and 0.1° for the calculated angle variable. Mean percentage errors between the DPMM and criterion reference values were equal to or less than 0.4%. Intratester and intertester reliabilities of DPMM-computed structural measures of arch and navicular indices were moderate to high (>0.78), and concurrent validity was moderate to strong.

CONCLUSIONS

The DPMM is a valid and reliable clinical and research tool for quantifying foot structure. The DPMM and the descriptive data might be used to define groups in future studies in which the relationship between foot posture and function or injury risk is investigated.

Relationship between static foot posture and foot mobility

Background

It is not uncommon for a person's foot posture and/or mobility to be assessed during a clinical examination. The exact relationship, however, between static posture and mobility is not known.

Objective

The purpose of this study was to determine the degree of association between static foot posture and mobility.

Method

The static foot posture and foot mobility of 203 healthy individuals was assessed and then analyzed to determine if low arched or "pronated" feet are more mobile than high arched or "supinated" feet.

Results

The study demonstrated that those individuals with a lower standing dorsal arch height and/or a wider standing midfoot width had greater mobility in their foot. In addition, those individuals with higher Foot Posture Index (FPI) values demonstrated greater mobility and those with lower FPI values demonstrated less mobility. Finally, the amount of foot mobility that an individual has can be predicted reasonably well using either a 3 or 4 variable linear regression model.

Conclusions

Because of the relationship between static foot posture and mobility, it is recommended that both be assessed as part of a comprehensive evaluation of a individual with foot problems.

Foot posture in people with medial compartment knee osteoarthritis

Background

Foot posture has long been considered to contribute to the development of lower limb musculoskeletal conditions as it may alter the mechanical alignment and dynamic function of the lower limb. This study compared foot posture in people with and without medial compartment knee osteoarthritis (OA) using a range of clinical foot measures. The reliability of the foot measures was also assessed.

Methods

The foot posture of 32 patients with clinically and radiographically-confirmed OA predominantly in the medial compartment of the knee and 28 asymptomatic age-matched healthy controls was investigated using the foot posture index (FPI), vertical navicular height and drop, and the arch index. Independent t tests and effect size (Cohen's d) were used to investigate the differences between the groups in the foot posture measurements.

Results

Significant differences were found between the control and the knee OA groups in relation to the FPI (1.35 ± 1.43 vs. 2.46 ± 2.18, p = 0.02; d = 0.61, medium effect size), navicular drop (0.02 ± 0.01 vs. 0.03 ± 0.01, p = 0.01; d = 1.02, large effect size) and the arch index (0.22 ± 0.04 vs. 0.26 ± 0.04, p = 0.04; d = 1.02, large effect size). No significant difference was found for vertical navicular height (0.24 ± 0.03 vs. 0.23 ± 0.03, p = 0.54; d = 0.04, negligible effect size).

Conclusion

People with medial compartment knee OA exhibit a more pronated foot type compared to controls. It is therefore recommended that the assessment of patients with knee OA in clinical practice should include simple foot measures, and that the potential influence of foot structure and function on the efficacy of foot orthoses in the management of medial compartment knee OA be further investigated.

The natural history and pathophysiology of flexible flatfoot

The frequent occurrence of flexible flatfoot raises the question of its pathologic status. There may be cultural overtones resulting in the consideration that flat feet are always pathologic. Parents may believe that their own flat feet were successfully treated when they were children and wish the same for their offspring. Few studies attempt to answer the question of the natural history of this condition. This article reviews the available literature dealing with the natural history, comorbidities, recommendations for treatment, expansion of biomechanical theory, and classification of flatfoot. Issues associated with imaging of flatfoot and the design of studies to validate the effects of treatment are also reviewed.

Inter-rater reliability of the Foot Posture Index (FPI-6) in the assessment of the paediatric foot

BACKGROUND

Reliability is an integral component of clinical assessment and necessary for establishing baseline data, monitoring treatment outcomes and providing robust research findings. In the podiatric literature traditional measures of foot assessment have been shown to be largely unreliable. The Foot Posture Index (FPI-6) is a clinical tool used in the assessment of foot and to date, there is limited research published which evaluates the reliability of this tool in children and adolescents.

METHOD

Thirty participants aged 5 - 16 years were recruited for the research. Two raters independently recorded the FPI-6 score for each participant.

RESULTS

Almost perfect agreement between the two raters was identified following weighted kappa analysis (Kw = 0.86).

CONCLUSION

The FPI-6 is a quick, simple and reliable clinical tool which has demonstrated excellent inter-rater reliability when used in the assessment of the paediatric foot.

Differences in static and dynamic measures in evaluation of talonavicular mobility in gait

STUDY DESIGN

Controlled laboratory study using a cross-sectional design.

OBJECTIVES

To compare the measurements of navicular drop during walking and running to those made clinically during a static position in a group of healthy young adults.

BACKGROUND

The navicular drop test is a common clinical measure of foot structure and, more specifically, of talonavicular joint function. Previous work has focused on static measurement to establish the relationship between navicular drop and various overuse injuries. However, loads on foot structure are dramatically increased during gait. Examining navicular drop dynamically is more reflective of the functional demands of the foot when walking and running.

METHODS

The navicular drop of 72 healthy runners was evaluated using 2 static methods. Results were used to classify individuals into groups and compared to dynamic measures of navicular drop made during walking and running. Three-dimensional motion capture and an instrumented treadmill were used to assess dynamic navicular mobility. A repeated-measures analysis of variance (ANOVA) was performed to examine differences between measurement conditions. Between-group differences were assessed with independent-samples t test (P<.05).

RESULTS

Static measures of navicular drop were not found to be uniformly predictive of dynamic function during walking or running. Functional navicular drop measurements underestimated the dynamic measures in all foot types, while subtalar neutral drop overestimated dynamic measures for individuals with neutral and hypermobile foot types. No differences in navicular drop were found between foot types during walking, and small differences were found in running only between the hypomobile and hypermobile foot types. Maximum foot deformation during gait occurs at the time of maximum ground reaction force. Significant differences in navicular drop between foot type groups measured statically become muted when looking at group differences while walking and running.

CONCLUSIONS

Differences in navicular mobility between foot type groups during walking and running indicate that factors other than static alignment affect dynamic foot mobility. Dynamic assessment of navicular mobility may be an effective tool to examine the interplay of how the extrinsic force demands of gait and intrinsic structure and neuromuscular control affect foot function in walking and running.

Determination of normal values for navicular drop during walking: a new model correcting for foot length and gender

Background

The navicular drop test is a measure to evaluate the function of the medial longitudinal arch, which is important for examination of patients with overuse injuries. Conflicting results have been found with regard to differences in navicular drop between healthy and injured participants. Normal values have not yet been established as foot length, age, gender, and Body Mass Index (BMI) may influence the navicular drop. The purpose of the study was to investigate the influence of foot length, age, gender, and BMI on the navicular drop during walking.

Methods

Navicular drop was measured with a novel technique (Video Sequence Analysis, VSA) using 2D video. Flat reflective markers were placed on the medial side of the calcaneus, the navicular tuberosity, and the head of the first metatarsal bone. The navicular drop was calculated as the perpendicular distance between the marker on the navicular tuberosity and the line between the markers on calcaneus and first metatarsal head. The distance between the floor and the line in standing position between the markers on calcaneus and first metatarsal were added afterwards.

Results

280 randomly selected participants without any foot problems were analysed during treadmill walking (144 men, 136 women). Foot length had a significant influence on the navicular drop in both men (p < 0.001) and women (p = 0.015), whereas no significant effect was found of age (p = 0.27) or BMI (p = 0.88). Per 10 mm increase in foot length, the navicular drop increased by 0.40 mm for males and 0.31 mm for females. Linear models were created to calculate the navicular drop relative to foot length.

Conclusion

The study demonstrated that the dynamic navicular drop is influenced by foot length and gender. Lack of adjustment for these factors may explain, at least to some extent, the disagreement between previous studies on navicular drop. Future studies should account for differences in these parameters.

Effects of low-dye taping on plantar pressure pre and post exercise: an exploratory study

Background

Low-Dye taping is used for excessive pronation at the subtalar joint of the foot. Previous research has focused on the tape's immediate effect on plantar pressure. Its effectiveness following exercise has not been investigated. Peak plantar pressure distribution provides an indirect representation of subtalar joint kinematics. The objectives of the study were 1) To determine the effects of Low-Dye taping on peak plantar pressure immediately post-application. 2) To determine whether any initial effects are maintained following exercise.

Methods

12 asymptomatic subjects participated; each being screened for excessive pronation (navicular drop > 10 mm). Plantar pressure data was recorded, using the F-scan, at four intervals during the testing session: un-taped, baseline-taped, post-exercise session 1, and post-exercise session 2. Each exercise session consisted of a 10-minute walk at a normal pace. The foot was divided into 6 regions during data analysis. Repeated-measures analysis of variance (ANOVA) was used to assess regional pressure variations across the four testing conditions.

Results

Reduced lateral forefoot peak plantar pressure was the only significant difference immediately post tape application (p = 0.039). This effect was lost after 10 minutes of exercise (p = 0.036). Each exercise session resulted in significantly higher medial forefoot peak pressure compared to un-taped; (p = 0.015) and (p = 0.014) respectively, and baseline-taped; (p = 0.036) and (p = 0.015) respectively. Medial and lateral rearfoot values had also increased after the second session (p = 0.004), following their non-significant reduction at baseline-taped. A trend towards a medial-to-lateral shift in pressure present in the midfoot immediately following tape application was still present after 20 minutes of exercise.

Conclusion

Low-Dye tape's initial effect of reduced lateral forefoot peak plantar pressure was lost after a 10-minute walk. However, the tape continued to have an effect on the medial forefoot after 20 minutes of exercise. Further studies with larger sample sizes are required to examine the important finding of the anti-pronatory trend present in the midfoot.

Reliability and normative values for the foot mobility magnitude: a composite measure of vertical and medial-lateral mobility of the midfoot

BACKGROUND

A study was conducted to determine the reliability and minimal detectable change for a new composite measure of the vertical and medial-lateral mobility of the midfoot called the foot mobility magnitude.

METHODS

Three hundred and forty-five healthy participants volunteered to take part in the study. The change in dorsal arch height between weight bearing and non-weight bearing as well as the change in midfoot width between weight bearing and non-weight bearing were measured at 50% of total foot length and used to calculate the foot mobility magnitude. The reliability and minimal detectable change for the measurements were then determined based on the assessment of the measurements by three raters with different levels of clinical experience.

RESULTS

The change in dorsal arch height between weight bearing and non-weight bearing, midfoot width between weight bearing and non-weight bearing, and the foot mobility magnitude were shown to have high levels of intra-rater and inter-rater reliability. Normative data are provided for the left and right feet of both the female (n = 211) and male (n = 134) subjects.

CONCLUSION

While the measurements of navicular drop and drift have been used as a clinical method to assess both the vertical and medial-lateral mobility of the midfoot, poor to fair levels of inter-rater reliability have been reported. The results of the current study suggest that the foot mobility magnitude provides the clinician and researcher with a highly reliable measure of vertical and medial-lateral midfoot mobility.

Effect of using truncated versus total foot length to calculate the arch height ratio

OBJECTIVE

The purpose of this study was to determine the arch height ratio in a large cohort of subjects as well as to assess the reliability and validity of the foot measurements utilized in the study.

METHOD

Eight hundred and fifty subjects, 393 women and 457 men, consented to participate in the study. The dorsal arch height, total foot length, and the truncated foot length were used to calculate two variations of the arch height ratio. In addition to determining within- and between-rater measurement reliability, radiographs were used to establish validity.

RESULTS

The truncated arch height ratio can be estimated using the total foot length, unless toe deformities are present in the individual being assessed. All foot measurements had high levels of intra- and inter-rater reliability and the validity of measuring the dorsal arch height while standing with equal weight on both feet was established.

CONCLUSIONS

This investigation provides normative values from a large cohort of healthy female and male subjects for two variations of the arch height ratio. The arch height ratio is a reliable and valid measurement that may prove useful to clinicians and researchers for the classification of foot posture.

The effect of low-dye taping on rearfoot motion and plantar pressure during the stance phase of gait

BACKGROUND

Low-dye (LD) taping is commonly used to reduce rearfoot pronation. No studies have previously investigated the effectiveness of LD taping using both plantar pressure distribution (F-Scan) and 3-D (CODA) analysis of rearfoot motion.

METHODS

20 healthy subjects with a navicular drop test exceeding 10 mm participated in the study. T tests were used to determine whether significant (p < 0.05) differences in plantar pressure and rearfoot motion occurred with LD taping.

RESULTS

LD taping resulted in statistically significant increases in peak plantar pressure in the lateral midfoot (p = 0.000), along with significant decreases in pressure in the medial forefoot (p = 0.014), and the medial (p = 0.000) and lateral hindfoot (p = 0.007). No significant changes occurred in the medial midfoot (p = 0.794) or lateral forefoot (p = 0.654). When assessed using motion analysis, taping resulted in a statistically significant decrease in rearfoot pronation (p = 0.006), supination (p = 0.025) and total rearfoot range of motion (p = 0.000). The mean rearfoot position during stance was not significantly different however (p = 0.188).

CONCLUSION

LD taping is associated with alterations in peak plantar pressure in the midfoot and forefoot that indicate reduced pronation with LD taping. However, LD taping appears to reduce both pronation and supination in the rearfoot, rather than simply reducing pronation, when assessed using 3D motion analysis. Therefore, it would appear that LD taping does indeed reduce pronation, by restricting rearfoot motion in general, rather than pronation specifically. The degree of change observed with LD taping was however very small, and further research is needed to clarify the clinical significance of these initial findings.

Knee valgus during drop jumps in National Collegiate Athletic Association Division I female athletes: the effect of a medial post

BACKGROUND

Female athletes land from a jump with greater knee valgus and ankle pronation/eversion. Excessive valgus and pronation have been linked to risk of anterior cruciate ligament injury. A medially posted orthosis decreases component motions of knee valgus such as foot pronation/eversion and tibial internal rotation.

HYPOTHESIS

We hypothesized a medial post would decrease knee valgus and ankle pronation/eversion during drop-jump landings in NCAA-I female athletes.

STUDY DESIGN

Controlled laboratory study.

METHODS

Knee and ankle 3-dimensional kinematics were measured using high-speed motion capture in 10 National Collegiate Athletic Association Division I female athletes during a drop-jump landing with and without a medial post. Analysis of variance was used to determine differences in posting condition, t tests were used to determine dominant-nondominant differences, and the Pearson correlation coefficient was used to determine relationships between variables.

RESULTS

Significant differences were found for all measures in the posted condition. A medial post decreased knee valgus at initial contact (1.24 degrees , P < .01) and maximum angle (1.21 degrees , P < .01). The post also decreased ankle pronation/eversion at initial contact (0.77 degrees , P < .01) and maximum angle (0.95 degrees , P = .039).

CONCLUSION

The authors have demonstrated a significant decrease in knee valgus and ankle pronation/eversion during a drop jump with a medial post placed in the athletes' shoes.

CLINICAL RELEVANCE

A medial post may be a potential means to decrease risk of anterior cruciate ligament injury.

Reliability and normative values of the foot line test: a technique to assess foot posture

STUDY DESIGN

Test-retest reliability.

OBJECTIVE

To examine the reliability and report normative values of a novel test, the foot line test (FLT), to describe foot morphology.

BACKGROUND

Numerous foot examinations are performed each day, but most existing examination techniques have considerable limitations regarding reliability and validity.

METHODS

One hundred thirty subjects with mean foot size 44 (41-50 European size) participated. Two examiners, blinded to each other's measurements, measured the right foot of the subjects twice and the left foot once. The position of the most medial aspect of the navicular in the mediolateral direction was projected vertically onto a piece of paper placed under the subject's foot, and compared to the position of the forefoot and hindfoot to obtain the FLT value.

RESULTS

FLT values ranged from -8 to 14 mm, with a mean (+/-SD) of 3.7 +/- 3.4 mm. The intratester reproducibility reported by SEM was 0.8 mm for tester 1 and 0.9 mm for tester 2, while intertester SEM was 1.4 mm for the right foot and 1.3 mm for the left foot. The intrarater ICC was 0.95 for tester 1 and 0.94 for tester 2, while the interrater ICC was 0.86 (left foot) and 0.83 (right foot). There was no significant association between foot size and FLT values.

CONCLUSION

The FLT is a reproducible technique to assess foot posture.