A comparison of footprint indexes calculated from ink and electronic footprints

Measurement of the Developing Foot in Shod and Barefoot Paediatric Populations: A Narrative Review

The theory that footwear may change foot shape dates back 100 years. Since this period, research has revealed the anatomical and functional consequences that footwear can cause to the foot. Children’s feet remain malleable as they undergo developmental changes until adolescence, which is why childhood is arguably a crucial period to understand how footwear can affect natural foot development. This review explored the development of the foot in children and adolescents and the methods used to measure the different foot structures; it comments on the key issues with some of these methods and gives direction for future research. Various internal and external factors can affect foot development; the main factors are age, gender, ethnicity, body mass index (BMI) and footwear habits. Research on how footwear can affect foot development has increased over the years and the final section of this review aimed to unpick the findings. Studies investigating the influence of footwear habits on foot length and width have established inconsistent findings. Many of the studies in the review did not control for internal and external factors that can affect foot development. There was also a limited number of studies that investigated hallux valgus angle and muscle strength differences in those with different footwear habits. Moreover, multiple studies in the final section of this review did not successfully examine the footwear habits of the participants and instead used observations or self-assessments, which is a major limitation. Future research should examine footwear behaviors and other confounding factors when investigating the development of the foot in children and adolescents. Moreover, researchers should critically evaluate the methods used to quantify the different structures of the foot to ensure valid and reliable parameters are being used.

Arch Height Index, Arch Rigidity Index, and Arch Stiffness Values in a Symptomatic Population

BACKGROUND

Studies of arch height index (AHI), arch rigidity index (ARI), and arch stiffness have primarily focused on healthy populations. Normative values of the aforementioned measurements in a pathologic sample may be useful in identifying relationships between arch structure and pathology.

METHODS

AHI was obtained bilaterally at 10% and 90% weightbearing conditions using the AHI measurement system. ARI and arch stiffness were calculated using AHI measurements. Dependent t tests compared right and left, dominant and nondominant, and injured and noninjured limbs. Dominant feet were compared between sexes using independent t tests. Relationships between arch stiffness and subcategories were examined using the coefficient of determination (R2). One-way analyses of variance determined differences between arch structure and number of pathologies or body mass index (BMI).

RESULTS

A total of 110 participants reported one (n = 55), two (n = 38), or three or more (n = 17) pathologies. Plantar fasciitis (n = 31) and hallux valgus (n = 28) were the most common. AHI, ARI, and arch stiffness did not differ between limbs or sexes for any comparisons. Between subgroups of BMI and number of pathologies, BMI influenced AHI (10% weightbearing) and arch stiffness (P < .05). Arch stiffness showed a weak relationship to AHI, where a higher AHI was associated with a stiffer arch (R2 = 0.06).

CONCLUSIONS

Normative arch structure values were established in a pathologic sample with a large incidence of plantar fasciitis and hallux valgus. Understanding relationships between arch structure and pathology is helpful for clinicians and researchers.

Investigation of the Relationships Among Clinical Measures of Foot Posture in Individuals with and Without Pronated Foot

BACKGROUND

Many indirect clinical techniques have been developed to assess foot posture; however, there is relatively little research investigating the relationships among these techniques. We investigated the relationships among the most commonly used clinical measures of foot posture-Foot Posture Index-6 (FPI-6), navicular drop (NDP), navicular drift (NDT), and static and dynamic arch indices (SAI and DAI)-in individuals with normal foot posture and those with pronated foot.

METHODS

Sixty-three individuals with FPI-6 scores of 0 to 12 were included. A digital caliper was used to measure NDP and NDT; SAI and DAI were measured by electronic pedobarography. Assessments were applied on the dominant foot. Pearson correlation coefficients were calculated to determine the relationships among measures. Participants were classified into two groups, pronated foot (n = 33) and normal foot posture (n = 30), based on FPI-6 scores, providing a multisegmental and multiplanar assessment. The independent-samples t test was used to compare groups regarding NDP, NDT, SAI, and DAI.

RESULTS

We found a high correlation between NDP and FPI-6 (r = 0.754) and between NDP and NDT (r = 0.778) (all P < .001). A moderate correlation was found between NDT and FPI-6 (r = 0.599) and between DAI and SAI (r = 0.519) (all P < .001). A negligible correlation was found between NDP and DAI (r = 0.268; P = .033). Furthermore, NDP, NDT, and DAI values were higher in individuals with pronated foot compared with those with normal posture (P < .001 for NDP and NDT; P = .022 for DAI), whereas SAI values were not (P = .837).

CONCLUSIONS

These results suggest that there are moderate-to-strong relationships among FPI-6, NDP, and NDT and between SAI and DAI. The NDP, NDT, and DAI are suitable for the classification of foot posture based on FPI-6 scores. This study can guide clinicians and researchers to associate the foot posture measures with each other.

A Reconfigurable and Adjustable Compliance System for the Measurement of Interface Orthotic Properties

Custom foot orthoses (CFOs) have shown treatment effectiveness by providing improved pressure/load redistribution, skeletal support and comfort level. However, the current design methodologies of CFOs have some problems: (1) the plantar surface is captured without considering the soft tissue impedance, (2) the stiffness of the CFOs is limited to rigid, semi-rigid and soft, which ignores the potential effect of local variation of stiffness on the interface pressure/load distribution and subjective evaluations, and (3) the lack of a human-in-the-loop may lead to multiple design-to-deliver iterations. A new prescription methodology of CFOs is required to satisfy the pressure/load distribution, improve comfort level and decrease iterations.

METHOD

A measurement system which provides INterface with Tunable Ergonomic properties using a Reconfigurable Framework with Adjustable Compliant Elements (INTERFACE system) is developed to implement the Rapid Evaluate and Adjust Device (READ) methodology. The geometry and stiffness of the Medial Longitudinal Arch (MLA) support provided by the INTERFACE system can be adjusted via linear actuators and tunable stiffness mechanisms, based on objective interface pressure/load distribution and subjective feedback evaluations. Validation tests were conducted on 13 subjects to measure the plantar pressure/load distribution and record the subjective feedback in different combinations of geometry and stiffness.

RESULTS

The interface pressure/load distribution and subjective feedback of the support level indicate the efficacy of the adjustable geometry and stiffness. As the stiffness and geometrical height increased, the plantar loadings increased in the MLA region and decreased in the rear foot. Geometrical fitting can be achieved with the reconfigurable MLA support. The integration of locally adjustable stiffness makes it possible to fine tune the plantar pressure/load and provides the subjects with options of orthotic stiffness.

CONCLUSION

The proposed INTERFACE system can be applied to conduct the measurement of the desired orthotic properties which satisfy the interface pressure/load requirement and the subject's comfort.

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.

A Deep-Learning Approach for Foot-Type Classification Using Heterogeneous Pressure Data

The human foot is easily deformed owing to the innate form of the foot or an incorrect walking posture. Foot deformations not only pose a threat to foot health but also cause fatigue and pain when walking; therefore, accurate diagnoses of foot deformations are required. However, the measurement of foot deformities requires specialized personnel, and the objectivity of the diagnosis may be insufficient for professional medical personnel to assess foot deformations. Thus, it is necessary to develop an objective foot deformation classification model. In this study, a model for classifying foot types is developed using image and numerical foot pressure data. Such heterogeneous data are used to generate a fine-tuned visual geometry group-16 (VGG16) and K−nearest neighbor (k-NN) models, respectively, and a stacking ensemble model is finally generated to improve accuracy and robustness by combining the two models. Through k-fold cross-validation, the accuracy and robustness of the proposed method have been verified by the mean and standard deviation of the f1 scores (0.9255 and 0.0042), which has superior performance compared to single models generated using only numerical or image data. Thus, the proposed model provides the objectivity of diagnosis for foot deformation, and can be used for analysis and design of foot healthcare products.

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.

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

AIM

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

METHODS

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

RESULTS

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

CONCLUSIONS

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

Reliability and minimum detectable change of measures of gait in children during walking and running on an instrumented treadmill

BACKGROUND

Instrumented treadmills that incorporate pressure platforms are increasingly used to characterize gait in children. Although footprint size is known to influence the measurement performance of pressure platforms, published evidence on the reliability of such systems for children's gait is lacking.

RESEARCH QUESTION

This study evaluated the test-retest reliability of temporospatial gait parameters and vertical ground reaction forces measured in healthy children during barefoot walking and running on a capacitance-based treadmill system.

METHODS

Temporospatial gait parameters, including cadence, stride length, stride duration, stance and swing phase durations and the magnitude and timing of conventional vertical ground reaction force peaks were determined on two occasions in 17 healthy children (mean age, 11 ± 2 years; height, 148.4 ± 9.3 cm; and mass, 43.3 ± 10 kg) during walking and running at preferred speed on an instrumented treadmill. Reliability was assessed using Intra Class Correlation Coefficients (ICC) and the standard error of measurement (SEM). The minimum detectable change (MDC95%) was also calculated.

RESULTS

ICC values ranged from 0.91-0.99 for all variables. When expressed as a percentage of the mean, the SEM was <5% for all gait parameters assessed during walking and running. The MDC95% values for gait parameters were typically higher during running than walking, and were ±4% of the gait cycle for temporal parameters, ±55 cm for stride length and ±0.1 bodyweights for peak vertical ground reaction force.

SIGNIFICANCE

Children's gait parameters varied by <5% between test occasions and were more consistent during walking than running. These findings provide clinicians and researchers with an index of the reliability and sensitivity of the treadmill to detect changes in common spatiotemporal gait parameters and vertical ground reaction forces in children.

Concurrent Validity of an Automated Footprint Detection Algorithm to Measure Plantar Contact Area During Walking

BACKGROUND

Monitoring footprints during walking can lead to better identification of foot structure and abnormalities. Current techniques for footprint measurements are either static or dynamic, with low resolution. This work presents an approach to monitor the plantar contact area when walking using high-speed videography.

METHODS

Footprint images were collected by asking the participants to walk across a custom-built acrylic walkway with a high-resolution digital camera placed directly underneath the walkway. This study proposes an automated footprint identification algorithm (Automatic Identification Algorithm) to measure the footprint throughout the stance phase of walking. This algorithm used coloration of the plantar tissue that was in contact with the acrylic walkway to distinguish the plantar contact area from other regions of the foot that were not in contact.

RESULTS

The intraclass correlation coefficient (ICC) demonstrated strong agreement between the proposed automated approach and the gold standard manual method (ICC = 0.939). Strong agreement between the two methods also was found for each phase of stance (ICC > 0.78).

CONCLUSIONS

The proposed automated footprint detection technique identified the plantar contact area during walking with strong agreement with a manual gold standard method. This is the first study to demonstrate the concurrent validity of an automated identification algorithm to measure the plantar contact area during walking.

Electronic measurement of plantar contact area during walking using an adaptive thresholding method for Medilogic® pressure-measuring insoles

BACKGROUND

Pressure-measuring insoles have the potential to measure plantar contact area (PA) during walking. However, they are not widely used for this purpose because of the need for a reliable process that can convert the insole output into PA. The purposes of this study were to: (1) develop an adaptive-threshold method for pressure-measuring insoles that can improve the accuracy of the PA measurements during walking, and (2) experimentally assess the accuracy and generalizability of this method.

METHODS

A sample of 42 healthy, ambulatory, young adults (age=24.3±3.2years, mass=67.2±16.9kg, height=1.63±0.08m) completed 10 trials walking on an elevated walkway while wearing Medilogic^® pressure-measuring insoles (sizes 35-45). A total of six insole sizes were considered. Insole data were converted to PA using three unique adaptive-thresholds that were based on percentages of the maximum sum of digital values (MSDV) during an analyzed step. Three values were considered: 0.1%, 0.2%, and 0.3% of the MSDV. Additionally, a fixed-threshold, which is typically used to estimate PA, was assessed. These two techniques, applied to the insole worn on the left foot, were compared with PA obtained from high-resolution reference footprints obtained from optical pedography of the right foot and processed using digital image processing algorithms. An assumption of PA symmetry between the left (insole) and right (barefoot) feet was made and comparisons were conducted over the entire stance phase of walking. The generalizability of the algorithm was assessed by comparing PA errors from insoles with respect to the optical pedography results based on insole size criteria.

RESULTS

The adaptive-thresholds of 0.1%, 0.2%, and 0.3% of MSDV produced mean errors of 7.31±17.44%, -8.62±15.01%, and -20.45±14.18%, respectively. Using the 2-digital value fixed-threshold produced a mean error of 20.88±22.44%. The best performing adaptive-threshold varied among insole sizes.

CONCLUSION

It was observed that the fixed-threshold technique produced large magnitudes of errors. The proposed adaptive-thresholds of 0.1% and 0.2% of the MSDV reduced PA error to ±10% during walking. The adaptive-threshold method consistently reduced PA error vs. the fixed-threshold for each insole size.

Reliability of a New Method to Determine Foot Arch Height for Clinicians

BACKGROUND

Arch height is an important indicator of risk of foot pathology. The current non-invasive gold standard based on footprint information requires extensive pre-processing. Methods used to obtain arch height that are accurate and easier to use are required in routine clinical practice.

METHODS

The proposed arch index diagonals (AI_d) method for determining the arch index (AI) reduces the complexity of the preprocessing steps. All footprints were first prepared as required by the Cavanagh and Rodgers method for determining the AI and then compared to the proposed diagonals method. Results were classified according to the Cavanagh and Rodgers cut-off values into three groups of low, normal and high AI. ANOVA and Tukey's post hoc tests were applied to identify significant differences between AI groups. Linear modeling was applied to determine the fit of the new AI_d method compared to the Cavanagh and Rodgers AI.

RESULTS

One hundred and ninety-six footprints were analyzed. The ANOVA indicated significant differences between the groups for AI_d (F1,194=94.49, p<0.0001) and the Tukey post hoc tests indicated significant differences between the pair-wise comparisons (p<0.001). Linear modeling indicated that the AI_d ratio classified more footprints in the high arch group compared to Cavanagh and Rodgers results (R²=32%, p< 0.01). Intra- and inter-rater correspondence was above 90% and confirmed that the AI_d results provided a better indication of arch height.

CONCLUSIONS

The proposed method simplifies current processing steps to derive the arch height.

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.

Normal foot loading parameters and repeatability of the Footscan® platform system

Background

The Footscan® platform system is one of the most commonly used clinical tools for the measurement of the foot pressure. The present study was designed to assess the repeatability of the system and identify the range of loading parameters observed in the normal foot.

Methods

Measurements were collected from 32 healthy participants, 15 females and 17 males, twice at an interval of 1 week. Peak pressure (PP), contact time (CT), contact area (CA), pressure-time integral (PTI), and maximum force (MaF) were recorded; these parameters were investigated in 10 areas of the foot: medial heel, lateral heel, midfoot, first to fifth metatarsals, hallux, and toes 2–5. The intra-session repeatability was evaluated by calculating the intraclass correlation coefficients (ICCs) and coefficients of variation (CVs) across the three repeated trials within the same session. The inter-session repeatability was assessed using the average of the three trials in each session to determine the ICCs and CVs.

Results

The ICCs showed moderate to good repeatability for every variable of interest, and the CVs were all <28%. The highest zones of PP were found under the second and third metatarsals, followed by the medial heel. The CT was 68.5–82.8% of the total stance time under the metatarsal heads. CA was highest under the midfoot, PTI was highest under the second metatarsal, and MaF was highest under the medial heel.

Conclusions

Footscan® platform system was found to be repeatable. Thus, it can be used as a valuable tool in the assessment of plantar pressure distribution, and the normal values of the foot loading parameters identified in this study can be employed to provide a reference range for the gait analysis performed by the Footscan® system.

Reliability and Accuracy of Static Parameters Obtained From Ink and Pressure Platform Footprints

OBJECTIVE

The purpose of this study was to evaluate the accuracy and the intrarater reliability of arch angle (AA), Staheli Index (SI), and Chippaux-Smirak Index (CSI) obtained from ink and pressure platform footprints.

METHODS

We obtained AA, SI, and CSI measurements from ink pedigraph footprints and pressure platform footprints in 40 healthy participants (aged 25.65 ± 5.187 years). Intrarater reliability was calculated for all parameters obtained using the 2 methods. Standard error of measurement and minimal detectable change were also calculated. A repeated-measure analysis of variance was used to identify differences between ink and pressure platform footprints. Intraclass correlation coefficient and Bland and Altman plots were used to assess similar parameters obtained using different methods.

RESULTS

Intrarater reliability was >0.9 for all parameters and was slightly higher for the ink footprints. No statistical difference was reported in repeated-measure analysis of variance for any of the parameters. Intraclass correlation coefficient values from AA, SI, and CSI that were obtained using ink footprints and pressure platform footprints were excellent, ranging from 0.797 to 0.829. However, pressure platform overestimated AA and underestimated SI and CSI.

CONCLUSIONS

Our study revealed that AA, SI, and CSI were similar regardless of whether the ink or pressure platform method was used. In addition, the parameters indicated high intrarater reliability and were reproducible.

A comparison of hallux valgus angles assessed with computerised plantar pressure measurements, clinical examination and radiography in patients with diabetes

BACKGROUND

Hallux valgus deformity is a common musculoskeletal foot disorder with a prevalence of 3.5% in adolescents to 35.7% in adults aged over 65 years. Radiographic measurements of hallux valgus angles (HVA) are considered to be the most reproducible and accurate assessment of HVA. However, in European countries, many podiatrists do not have direct access to radiographic facilities. Therefore, alternative measurements are desired. Such measurements are computerised plantar pressure measurement and clinical goniometry. The purpose of this study was to establish the agreement of these techniques and radiographic assessments.

METHODS

HVA was determined in one hundred and eighty six participants suffering from diabetes. Radiographic measurements of HVA were performed with standardised static weight bearing dorsoplantar foot radiographs. The clinical goniometry for HVA was measured with a universal goniometer. Computerised plantar pressure measurement for HVA was executed with the EMED SF-4® pressure platform and Novel-Ortho-Geometry software. The intra-class correlation coefficients (ICC) and levels of agreement were analysed using Bland & Altman plots.

RESULTS

Comparison of radiographic measurements to clinical goniometry for HVA showed an intraclass correlation coefficient (ICC) of 0.81 (95% confidence interval, 0.76 to 0.86; p<0.001). Radiographic measurement versus computerised plantar pressure measurement showed an ICC of 0.59 (95% confidence interval, 0.49 to 0.68; p<0.001). In addition, clinical goniometry versus computerised plantar pressure measurement showed an ICC of 0.77 (95% confidence interval, 0.70 to 0.82; p<0.001). The systematic difference of the computerised plantar pressure measurement compared with radiographic measurement and clinical goniometry was 7.0 degrees (SD 6.8) and 5.2 degrees (SD 5.0), respectively. The systemic difference of radiographic measurements compared with clinical goniometry was 1.8 degrees (SD 5.0).

CONCLUSIONS

The agreement of computerised plantar pressure measurement and clinical goniometry for HVA compared to radiographic measurement of HVA is unsatisfactory. Radiographic measurements of HVA and clinical goniometry for HVA yield better agreement compared to radiographic measurements and computerised plantar pressure measurement. The traditional radiographic measurement techniques are strongly recommended for the assessment of HVA.

Dynamic footprint measurement collection technique and intrarater reliability: ink mat, paper pedography, and electronic pedography

BACKGROUND

Identifying the variability of footprint measurement collection techniques and the reliability of footprint measurements would assist with appropriate clinical foot posture appraisal. We sought to identify relationships between these measures in a healthy population.

METHODS

On 30 healthy participants, midgait dynamic footprint measurements were collected using an ink mat, paper pedography, and electronic pedography. The footprints were then digitized, and the following footprint indices were calculated with photo digital planimetry software: footprint index, arch index, truncated arch index, Chippaux-Smirak Index, and Staheli Index. Differences between techniques were identified with repeated-measures analysis of variance with post hoc test of Scheffe. In addition, to assess practical similarities between the different methods, intraclass correlation coefficients (ICCs) were calculated. To assess intrarater reliability, footprint indices were calculated twice on 10 randomly selected ink mat footprint measurements, and the ICC was calculated.

RESULTS

Dynamic footprint measurements collected with an ink mat significantly differed from those collected with paper pedography (ICC, 0.85-0.96) and electronic pedography (ICC, 0.29-0.79), regardless of the practical similarities noted with ICC values (P = .00). Intrarater reliability for dynamic ink mat footprint measurements was high for the footprint index, arch index, truncated arch index, Chippaux-Smirak Index, and Staheli Index (ICC, 0.74-0.99).

CONCLUSIONS

Footprint measurements collected with various techniques demonstrate differences. Interchangeable use of exact values without adjustment is not advised. Intrarater reliability of a single method (ink mat) was found to be high.

Estudo da impressão plantar obtida durante o teste de Jack em crianças

OBJETIVO: Avaliar as impressões plantares durante o teste de Jack em crianças quantificando e observando os resultados numa faixa etária crítica para a formação do arco plantar. MÉTODO: Avaliamos 60 crianças brancas (120 pés) sendo 35 meninos e 25 meninas com idades entre 2 e 5 anos, sem queixas ortopédicas. Simulamos o teste de Jack com uma órtese em cunha de 45º apoiada sob o hálux. Obtivemos impressões em apoio monopodálico bilateralmente utilizando um pedígrafo. O exame dividiu-se em duas etapas: com e sem o uso da órtese. A metodologia de Valenti e Volpon foi utilizada para mensurar as impressões plantares e os dados obtidos foram analisados estatisticamente. RESULTADOS: Os valores dos índices de Valenti e Volpon diminuiram quando a órtese foi utilizada. A diferença entre os índices com ou sem órtese diminuiu gradualmente com a progressão etária. CONCLUSÕES: É possível quantificar o teste de Jack pelwas impressões plantares pelo método de Valenti e Volpon. A variação do seu formato apresentou tendência a ser menor a partir dos 4 anos. O teste de Jack perdeu gradativamente a capacidade de modificar a impressão plantar com a idade, diminuindo sua acuidade como parâmetro de bom prognóstico na formação do arco longitudinal medial. Nível de Evidência: Nível IV, estudo descritivo observacional.

Static measure of foot loading

Static and dynamic loading of the foot are important characteristics for understanding human walking in both health and disease. The goal of this investigation was to determine whether an objective measure of normal midstance loading of the foot could reliably be recorded using readily available disposable qualitative recording devices. Ten randomly selected normal volunteers were trained to step on Harris mat and Pressure Stat recording devices during normal walking. Each of the recordings was divided into 5 weight-bearing regions by 2 separate examiners. After outlining each foot, the recordings were digitized and compared. Interobserver reliability ranged from 0.81 to 0.96 for the Harris mat technique and 0.94 to 0.97 for the Pressure Stat technique. Data from a linear regression plot indicate high precision of calculations of the foot masks between the 2 examiners based on an R(2) value of 0.966 using the Pressure Stat method. These data plus a linear regression plot suggest that both qualitative recording devices, when digitized using a standardized format, appear to obtain a reliable objective measure of midstance loading during normal gait. The Pressure Stat device may be slightly more reliable. It is planned to use this standardized experimental model to compare objectively patterns of midstance loading in patients with injury or disease that is capable of altering normal walking.

Assessment of sub-division of plantar pressure measurement in children

Methods for the measurement of plantar pressure are poorly defined particularly when describing sub-sections of the plantar surface of the foot in the presence of deformity. The aim of this study was to assess foot pressure measurement in healthy children, using an automatic technique of sub-area definition that has the potential for objective evaluation of treatment of foot deformity. Twelve healthy children were examined on three occasions. Plantar pressure data were collected and time synchronised with force plate and stereophotogrammetric data. The footprint was divided into five sub-sections by using the position of the markers on the foot at mid-stance projected onto the pressure footprint. Repeatability for peak pressure and peak force was assessed. Automatic sub-area definition based on marker placement was found to be reliable in healthy children. A comparison of results revealed that peak vertical force was a more consistent measure than peak pressure for each of the five sub-areas. This suggests that force may be a more appropriate measurement for outcome studies.

Giannini prosthesis for flatfoot

BACKGROUND

To determine the clinical and radiographic results of arthroereisis using the Giannini endo-orthotic implant for the treatment of pediatric flatfoot deformity, we retrospectively evaluated 37 patients (65 feet).

METHODS

Twenty-two boys and 15 girls were followed for an average of 26.5 months. Their overall average age was 9.4 (range 5 to 14) years. Pain, function, participation in sports activity, and the changes in radiographic measurements taken at 3, 6, and 12 months and then at 1-year intervals were evaluated.

RESULTS

Pain or discomfort decreased from 60% (22 patients) preoperatively to 6% (2 patients) postoperatively. The percentage of normal postoperative footprints was 59% (38 feet) with first-degree flatfoot present in 27 feet (41%). Sports activities were taken up by 19 patients (51%) after surgery. An 8-mm endo-orthotic implant was used in 43 (66%) feet and an Achilles tenotomy was done in 38 feet (59%). The radiographic angles with the greatest degree of correction when compared to preoperative angles were the talar-first metatarsal angle (99%) and the calcaneal-pitch (36%). After placement of the endo-orthotic implant, the talar angle influenced the rest of the radiographic measurements. There was no postoperative deterioration in any of the radiographic angles measured during the monitoring period. Complications occurred in 10.7% of the patients, with postoperative pain being the most frequently reported (6% of patients). There was no infection or local reaction to a foreign body. Removal of the endo-orthotic implant was not done on a routine basis.

CONCLUSION

This operative technique respects the anatomical structure of the foot and produces good clinical and radiographic results.

Efficacy of plantar loading parameters during gait in terms of reliability, variability, effect of gender and relationship between contact area and plantar pressure

BACKGROUND

The purpose of this study was to determine plantar pressure and contact areas of the foot inside the athletic shoe during activity. The objectives were to determine if plantar pressure and contact area measurements collected on multiple trials from the same subject were reliable, to determine the variability of measurements between subjects as compared to that found between steps within a single subject, to determine the relationship between contact area and plantar pressure, and to ascertain whether there were any systematic gender differences in these measurements.

METHODS

Sixteen healthy adults volunteered for participation in the first part of the study that was designed to determine reliability and variability of the testing methodology. A separate group of fifty healthy high school and collegiate athletes participating in soccer, field hockey, basketball, and lacrosse comprised the second part of the study that was designed to investigate gender differences in terms of normalized midfoot plantar pressure and contact area, and the interrelationship between the two measurements. Data were collected during the midstance phase of gait, using the Pedar in-shoe measurement system (Novel GMBH, St. Paul, MN). Athletes wore their own athletic shoes and performed walking trials on a surface similar to that used in their sport. The foot was divided into four regions based on radiographic measurements.

RESULTS

The midfoot region demonstrated excellent reliability across multiple trials of the same subject in contact area and plantar pressure, and the variability between steps within a single subject was small when compared to that between subjects. Normalized midfoot contact area and plantar pressure values were highly correlated with r values of 0.862 on the left foot and .912 on the right foot. No significant differences were found in normalized midfoot contact area or plantar pressure values between males and females.

CONCLUSIONS

The Pedar in-shoe pressure measurement system can be used reliably to quantify contact area and plantar pressure beneath the midfoot region during the midstance phase of gait. This measurement technique can now be used in risk factor studies designed to identify individuals at risk for injury to the foot, ankle, and other lower extremity structures.

The arch index: a measure of flat or fat feet?

BACKGROUND

Studies using footprint-based estimates of arch height have indicated that obesity results in a lowered medial longitudinal arch in children. However, the potentially confounding effect of body composition on indirect measures of arch height, such as the arch index, has not been investigated.

METHODS

This study assessed the body composition of 12 male and 12 female adults (mean age: 39.9 +/- 8.1 years, height: 1.724 +/- 0.101 m; weight: 95.1 +/- 13.7 kg, and BMI: 31.9 +/- 3.0 kg/m(2)) using bioelectrical impedance analysis to produce a two-component model of fat mass (FM) and fat-free mass (FFM). The dynamic arch index also was determined from electronic footprints captured during gait using a capacitive pressure distribution platform with a resolution of 4 sensors/cm(2).

RESULTS

While significant correlations were noted between FFM and the area of both the hindfoot (r =.75, p <.05) and forefoot (r =.72, p <. 05), the midfoot area was correlated only with FM (r =.54, p <.05). Similarly, the arch index was significantly correlated with the FM percentage (r =.67, p <.05).

CONCLUSIONS

The findings of this pilot study suggest that body composition influences arch index values in overweight and obese subjects. Consequently, body composition may be a confounding factor in interpreting footprint based estimates of arch height and, as such, these estimates would best be used with supplementary measures of body composition.