Ability of a multi-segment foot model to measure kinematic differences in cavus, neutrally aligned, asymptomatic planus, and symptomatic planus foot types.

BACKGROUND: Multi-segment foot models (MFMs) provide a better understanding of the intricate biomechanics of the foot, yet it is unclear if they accurately differentiate foot type function during locomotion. RESEARCH QUESTION: We employed an MFM to detect subtle kinematic differences between foot types, including: pes cavus, neutrally aligned, and asymptomatic and symptomatic pes planus. The study investigates how variable the results of this MFM are and if it can detect kinematic differences between pathologic and non-pathologic foot types during the stance phase of gait. METHODS: Independently, three raters instrumented three subjects on three days to assess variability. In a separate cohort, each foot type was statically quantified for ten subjects per group. Each subject walked while instrumented with a four-segment foot model to assess static alignment and foot motion during the stance phase of gait. Statistical analysis performed with a linear mixed effects regression. RESULTS: Model variability was highest for between-day and lowest for between-rater, with all variability measures being within the true sample variance. Almost all static measures (radiographic, digital scan, and kinematic markers) differed significantly by foot type. Sagittal hindfoot to leg and forefoot to leg kinematics differed between foot types during late stance, as well as coronal hallux to forefoot range of motion. The MFM had low between-rater variability and may be suitable for multiple raters to apply to a single study sample without introducing significant error. The model, however, only detected a few dynamic differences, with the most dramatic being the hallux to forefoot coronal plane range of motion. SIGNIFICANCE: Results only somewhat aligned with previous work. It remains unclear if the MFM is sensitive enough to accurately detect different motion between foot types (pathologic and non-pathologic). A more accurate method of tracking foot bone motion (e.g., biplane fluoroscopy) may be needed to address this question.

Do foot type classifications differ between male and female netball players? A cluster analysis.

We must better understand the foot type classifications of netball players to develop sex and size-specific shoe lasts. Five hundred and two representative-level netball players (n = 251 male; n = 251 female) had their feet three-dimensionally scanned. A validated MATLAB code was used to extract six different foot measurements from these scans automatically. We then used a two-step cluster analysis and chi-squared tests to classify foot types and determine the effect of sex on each cluster, respectively. Five foot types were identified (Extra long-and-wide, Long-and-wide, Flat, Tapered and Short-and-narrow), with sex significantly affecting foot type classification. The feet of players wearing smaller shoe sizes were often Short-and-narrow and Tapered, whereas the feet of players wearing larger sizes tended to be more Extra long-and-wide and Long-and-wide. These results highlight that netball players have a wide variety of foot types; manufacturers should use these data to develop future grading systems to improve the fit and functionality of netball-specific footwear.

This study aimed to investigate the foot types of netball players. The results demonstrated that five main foot types should be used to inform future shoe last designs and size grading systems. These findings have implications for improving the fit and functionality of netball shoes, particularly for men.

A deep learning method for foot-type classification using plantar pressure images.

Background: Flat foot deformity is a prevalent and challenging condition often leading to various clinical complications. Accurate identification of abnormal foot types is essential for appropriate interventions. Method: A dataset consisting of 1573 plantar pressure images from 125 individuals was collected. The performance of the You Only Look Once v5 (YOLO-v5) model, improved YOLO-v5 model, and multi-label classification model was evaluated for foot type identification using the collected images. A new dataset was also collected to verify and compare the models. Results: The multi-label classification algorithm based on ResNet-50 outperformed other algorithms. The improved YOLO-v5 model with Squeeze-and-Excitation (SE), the improved YOLO-v5 model with Convolutional Block Attention Module (CBAM), and the multilabel classification model based on ResNet-50 achieved an accuracy of 0.652, 0.717, and 0.826, respectively, which is significantly higher than those obtained using the ordinary plantar-pressure system and the standard YOLO-v5 model. Conclusion: These results indicate that the proposed DL-based multilabel classification model based on ResNet-50 is superior in flat foot type detection and can be used to evaluate the clinical rehabilitation status of patients with abnormal foot types and various foot pathologies when more data on patients with various diseases are available for training.

Agreement between clinical measures to classify foot posture in asymptomatic adults.

BACKGROUND: Various clinical measures of static foot posture have been developed and used. However, consensus among clinical measures to classify foot posture remains to be established. Therefore, this study aimed to determine the level of agreement as a reliability component between two common clinical methods in asymptomatic adults: the normalised navicular height truncated (NNHt) and the Foot Posture Index-6 (FPI-6). METHODS: The NNHt and FPI-6 were conducted on 102 asymptomatic adults. The measurement sequence was randomly arranged for each participant. Weighted Kappa (Kw) was used to determine the agreement between the methods. RESULTS: Both the NNHt and FPI-6 achieved similar foot posture distributions: approximately 40-50% of the participants had a normal foot, approximately 40% had a pronated foot and approximately 10-20% had a supinated foot. The agreement between the methods to classify foot posture was excellent (Kw = 0.84). CONCLUSIONS: The present study found excellent agreement between two commonly used clinical measures. This finding highlights the NNHt and FPI-6 consensus for foot posture classification in asymptomatic adults.

OASIS 2: Mobility differences with specific prosthetic feet across procedure codes.

Introduction: Recently, many prosthetic devices were subjected to reimbursement coding review. Several prosthetic feet that were historically coded with the shock-attenuating function were recoded. The purpose of this analysis was to compare patient-reported functional mobility across a range of prosthetic feet using real-world clinical outcomes data. Methods: A retrospective, observational review. A univariate generalized linear model was used to assess mobility across foot categories and between different prosthetic feet coded as L5987 or L5981. Results: The final sample analyzed comprised of 526 individuals and four mutually exclusive categories of feet examined across a total of 10 different prosthetic foot types. The comparison of prosthetic foot categories were significantly different from the control category (i.e. historically L5981). Conclusions: The current data suggest the development of some prosthetic foot designs using advanced materials and geometric designs can provide comparable functional benefits as those with distinct shock absorbing mechanical features. Emphasizing functional performance over visible features may be a pathway towards higher performance for the end user.

Is the Planus Foot Type Associated With First Ray Hypermobility?

Background: Many foot pathologies have been associated with foot type. However, the association of first ray hypermobility remains enigmatic. The purpose of this study was to investigate first ray hypermobility among participants with planus and rectus foot types and its influence on static measures of foot structure. Methods: Twenty asymptomatic participants with planus (n = 23 feet) and rectus (n = 17 feet) foot types were enrolled. Several parameters of static foot structure (arch height index, arch height flexibility, first metatarsophalangeal joint flexibility, and first ray mobility) were measured. Participants were further stratified into groups with nonhypermobile (n = 26 feet) and hypermobile (n = 14 feet) first rays. First ray mobility ≥8 mm was used to define "first ray hypermobility". Generalized estimating equations, best-fit regression lines, and stepwise linear regression were used to identify significant differences and predictors between the study variables. Results: Overall, 86% of subjects categorized with first ray hypermobility exhibited a planus foot type. Arch height flexibility, weightbearing first ray mobility, and first metatarsophalangeal joint flexibility showed no significant between-group differences. However, weightbearing ray mobility and first metatarsophalangeal joint laxity were associated with partial weightbearing first ray mobility, accounting for 38% of the model variance. Conclusion: The planus foot type was found to be associated with first ray hypermobility. Furthermore, weightbearing first ray mobility and first metatarsophalangeal joint laxity were predictive of partial weightbearing first ray mobility, demonstrating an interaction between the translation and rotational mechanics of the first ray. Clinical Relevance: Association of first ray hypermobility with foot type and first metatarsophalangeal joint flexibility may help understand the sequela to symptomatic pathologies of the foot.

Finite Element Modeling of Planus and Rectus Foot Types for the Study of First Metatarsophalangeal and First Metatarsocuneiform Joint Contact Mechanics.

The foot is a highly complex biomechanical system for which finite element (FE) modeling has been used to evaluate its loading environment. However, there is limited knowledge of first metatarsophalangeal (MTP) and first metatarsocuneiform (MTC) joint contact mechanics. Our goal was to develop a framework for FE modeling of the medial forefoot which could accurately predict experimental measurements of first MTP and first MTC joint loading. Simulations of planus and rectus foot types were conducted for midstance of gait. A custom-built force-controlled cadaveric test-rig was used to derive intracapsular pressure sensor measurements of contact pressure, force, and area during quasi-static loading. The FE model was driven under the same boundary and loading conditions as the cadaver. Mesh sensitivity analyses and best-fit calibrations of moduli for first MTP and first MTC joint cartilage were performed. Consistent with previous experimental research, a lower compressive modulus was best-fit to the first MTP compared to first MTC joint at 10 MPa and 20 MPa, respectively. Mean errors in contact pressures, forces, and areas were 24%, 4%, and 40% at the first MTP joint and 23%, 12%, and 19% at the first MTC joint, respectively. The present developmental framework may provide a basis for future modeling of first MTP and first MTC joint contact mechanics. This study acts as a precursor to validation of realistic physiological loading across gait to investigate joint loading, foot type biomechanics, and surgical interventions of the medial forefoot.

Footprint measurement methods for the assessment and classification of foot types in subjects with Down syndrome: a systematic review.

BACKGROUND: Musculoskeletal disorders, especially in the feet, are common in people with Down syndrome (DS). Evaluation of podiatric footprints is important to prevent and manage orthopedic symptoms. The reliability of a wide variety of footprint measurement methods has been evaluated in healthy people, but few studies have considered the specific morphotype features of the feet in subjects with DS. The aim of this systematic review was to identify the podometric measurement tools used to typologically classify the footprints in the population with DS. METHODS: The following electronic databases were searched for studies describing footprint measurement tools to assess and classify the foot types in patients with DS published from inception to December 2020: PubMed, Web of Science, CINAHL, and Scopus. Articles were initially searched by screening titles and abstracts. Potentially relevant studies were then further screened by reviewing full texts. Studies that met the inclusion criteria were included in the review. RESULTS: Of the 122 articles identified by the search strategy, 14 full texts were retained to assess for eligibility, of which 11 studies met the inclusion criteria and were included. All the studies used footprint measurement methods to classify the foot types in subjects with DS, but only two studies assessed the reliability of those methods for the population with DS. The footprint measurement tools identified were a podoscope, a pressure-sensitive mat, a PressureStatTM carbon paper, and a 3D scanner. The Arch Index was the most common footprint measurement analyzed (seven studies). Two studies used the "gold standard" indexes that include Hernández-Corvo Index, Chippaux-Smirak Index, Staheli Index, and Clarke Angle to measure footprints. CONCLUSIONS: There is a need to determine the reliability and validity of the footprint measurement methods used for clinical classification of the foot types in subjects with DS. This can contribute to an early diagnosis of foot abnormalities that would help to reduce mobility impairments, improving the quality of life of patients with DS.

Foot Posture and Plantar Loading With Ankle Bracing.

CONTEXT: Arch height is one important aspect of foot posture. An estimated 20% of the population has pes planus and 20% has pes cavus. These abnormal foot postures can alter lower extremity kinematics and plantar loading and contribute to injury risk. Ankle bracing is commonly used in sport to prevent these injuries, but no researchers have examined the effects of ankle bracing on plantar loading. OBJECTIVE: To evaluate the effects of ankle braces on plantar loading during athletic tasks. DESIGN: Cross-sectional study. SETTING: Laboratory. PATIENTS OR OTHER PARTICIPANTS: A total of 36 participants (11 men, 25 women; age = 23.1 ± 2.5 years, height = 1.72 ± 0.09 m, mass = 66.3 ± 14.7 kg) were recruited for this study. INTERVENTION(S): Participants completed walking, running, and cutting tasks in 3 bracing conditions: no brace, lace-up ankle-support brace, and semirigid brace. MAIN OUTCOME MEASURE(S): We analyzed the plantar-loading variables of contact area, maximum force, and force-time integral for 2 midfoot and 3 forefoot regions and assessed the displacement of the center of pressure. A 3 × 3 mixed-model repeated-measures analysis of variance was used to determine the effects of brace and foot type (α = .05). RESULTS: Foot type affected force measures in the middle (P range = .003-.047) and the medial side of the foot (P range = .004-.04) in all tasks. Brace type affected contact area in the medial midfoot during walking (P = .005) and cutting (P = .01) tasks, maximum force in the medial and lateral midfoot during all tasks (P < .001), and force-time integral in the medial midfoot during all tasks (P < .001). Portions of the center-of-pressure displacement were affected by brace wear in both the medial-lateral and anterior-posterior directions (P range = .001-.049). CONCLUSIONS: Ankle braces can be worn to redistribute plantar loading. Additional research should be done to evaluate their effectiveness in injury prevention.

The Design and Validation of a Low-Cost Foot Measurement System.

It is estimated that approximately 40% of the population suffers from abnormal foot posture, specifically high arched or low arched feet. While the evaluation of foot posture can involve many aspects, it commonly requires the measurement of basic dimensions of the foot. Clinicians and researchers often rely on the use of specialized devices or three-dimensional (3D) scanners to evaluate specific aspects of a patient's foot posture. However, current technologies are extremely expensive, therefore highlighting the need for a cost-effective device to be used in rural and clinical settings. As a result, the purpose of this study was to develop an inexpensive system to measure total foot length, truncated length, dorsum height, navicular height, and foot width. Bland-Altman plots showed significant differences between this measurement system and a 3D scanner for total foot length, truncated length, and navicular height (p < 0.001) and significant differences when assessing the repeatability of dorsum height (p = 0.022). However, the magnitudes of these differences were minimal compared to the overall measurement. Additionally, interclass correlation coefficients revealed that this system had excellent validity when compared to a 3D scanner (interclass correlation coefficients = 0.908-0.994), and good to excellent repeatability when compared between days (interclass correlation coefficients = 0.867-0.996). These results demonstrate that it is possible to design an inexpensive, valid, and repeatable system that can be used in clinical, research, and rural settings to successfully evaluate basic dimensions of the foot that can be used for the determination of foot type.

Gluteus medius muscle activity during gait in people with and without chronic nonspecific low back pain: A case control study.

BACKGROUND: Research investigating differences in gluteus medius muscle activity in those with and without chronic nonspecific low back pain is both limited and conflicting. Additionally, in these populations the relationship between gluteus medius muscle activity, foot type, and transversus abdominis muscle thickness is unclear. RESEARCH QUESTION: We aimed to investigate gluteus medius muscle activity during gait in those with and without chronic nonspecific low back pain. Secondarily, we aimed to explore the association between gluteus medius muscle activity, foot type, and transversus abdominis muscle thickness within groups. METHODS: This case control study recruited 30 people with and 30 people without chronic nonspecific low back pain and matched participants by age (±5 years), sex, and body mass index (±2 BMI units). Gluteus medius muscle activity was measured with surface electromyography during walking gait, with foot type and transversus abdominis muscle thickness measured with the Foot Posture Index and ultrasound respectively. The Mann-Whitney U test was used to investigate differences in gluteus medius muscle activity between groups. Spearman rank order correlation was performed to explore the association between gluteus medius muscle activity, foot type, and transversus abdominis thickness within each group. A linear regression was used to analyse significant correlations (P < 0.05). RESULTS: We found no significant differences in gluteus medius muscle activity between groups. However, there was a moderate correlation between the Foot Posture Index score and gluteus medius peak amplitude (P = 0.04) for those with mild to moderate chronic nonspecific low back pain. SIGNIFICANCE: Clinicians should be aware that patients with mild to moderate chronic nonspecific low back pain may not demonstrate significant differences in gluteus medius muscle activity compared to those without back pain. Additionally, higher peak gluteus medius muscle activity is likely to occur in people with mild to moderate chronic nonspecific low back pain and planus feet.

In-growing toe nail results of segmental matrix excision.

INTRODUCTION: In-growing toenails commonly affect young men hampering the quality of life. There are many methods to treat in-growing toe nail but most of them have high recurrence rates and poor patient satisfaction. We describe our results of segmental matrix excision for correction of ingrowing toe nails. MATERIAL AND METHODS: It is a retrospective study over a period of 2 years. Patients with symptomatic in-growing toe nails with stage II and III were operated by technique of segmental matrix excision. All patients were available for follow-up at ∼1 year. RESULTS: 90 patients, 59 males and 31females with ingrowing nail of great toe (108 toes and 120 surgical sites) that underwent correction of by segmental matrix excision. Patient's age ranged from 19 to 59 years. There was involvement of right great toe in 42 patients, left great toe in 30 patients and bilateral toes in 18 patients. 12 great toes were affected on both sides (74 lateral sides and 46 medial sides of toes). 15/90 (16.6%) patients had history of previous failed surgery by nail plate avulsion. Complications include bleeding (n = 1), infection (n = 2). On average follow up of ∼1 year, there was only 1 recurrence. There was no loss of cutaneous innervation or osteomyelitis. All patients went back to their normal activity on 10th day. CONCLUSION: Segmental matrix excision should be considered as the treatment of choice for ingrowing toe nail because of high cure rate, less pain, low risk of postoperative infection, and results in good cosmetic result.

An exploratory study investigating the effect of foot type and foot orthoses on gluteus medius muscle activity.

BACKGROUND: Abnormal gluteus medius muscle activity is associated with a number of musculoskeletal conditions. Research investigating the effect of foot type and foot orthoses on gluteus medius muscle activity is both conflicting and limited. The primary aim was to investigate the relationship between foot type and gluteus medius muscle activity during shod walking. The secondary aims of this study were to explore the effect and amount of usage of a pair of unmodified prefabricated foot orthoses on gluteus medius muscle activity during shod walking. METHODS: Foot type was determined using the foot posture index and gluteus medius muscle activity was measured with surface electromyography in 50 healthy adults during shod walking. Participants were then fitted with prefabricated foot orthoses and required to return after 4 weeks. Pearson's correlation and one-way ANOVA were used to determine effect of foot type. Paired t-tests and ANCOVA were used to determine effect of foot orthoses. RESULTS: Participants with a cavus foot type demonstrated significantly more gluteus medius mean (p = 0.04) and peak amplitude (p = 0.01), and a greater range in amplitude (p = 0.01) compared to participants with a neutral foot type. Compared to a planus foot type, participants with a cavus foot type demonstrated significantly larger mean (p = 0.02) and peak amplitude (p = 0.01), and a greater range in amplitude (p = 0.01). Prefabricated foot orthoses did not change the gluteus medius muscle activity. CONCLUSION: When assessing healthy adults with a cavus foot type, clinicians and researchers should be aware that these participants may display higher levels of gluteus medius muscle activity during gait compared to neutral and planus type feet. Additionally, clinicians and researchers should be aware that the type of prefabricated foot orthoses used did not change gluteus medius muscle activity over 4 weeks. Future research should aim to explore this relationship between foot type and gluteus medius muscle activity in larger sample sizes, consider the potential role of other lower extremity muscles and biomechanical variables, and investigate if these findings also occur in people with pathology.

The effect of foot type, body length and mass on postural stability.

BACKGROUND: Poor postural stability is associated with chronic ankle instability. Previous research showed an effect of foot type on postural stability. However, the specific effect of supinated feet remains unclear. RESEARCH QUESTION: Our study aimed to assess the effect of foot type on postural stability, while taking potential confounding effects of body mass and body height into account. METHODS: Forty-three healthy participants between 18 and 40 years old performed barefooted single leg stance tests with eyes open (EO) and closed (EC) on solid ground, and on a balance board (BB). Foot type was determined from pressure recordings during gait, using the arch index. Ground reaction forces were measured using a force plate. Outcome measures were Center of Pressure Velocity (COPV) divided by body height, and the Horizontal Ground Reaction Force (HGRF) divided by body mass. Generalized Estimating Equations models assessed the differences between supinated, normal and pronated feet during EO, EC and on a BB. RESULTS: During EO an interaction between supinated feet and body mass showed an increase of COPV with 0.03 × 10-2 1/s per kilogram of mass relative to normal feet (p = .03). During EC this interaction was more pronounced with 0.22 × 10-2 1/s increase per kilogram mass (p < .01). The HGRF did not differ between foot types in any of the conditions. SIGNIFICANCE: Supinated feet have a larger increase in COPV compared to normal feet with increasing mass when standing on solid ground during EO and EC. This indicates that people with supinated feet and a higher mass are less stable during single leg stance. LEVEL OF EVIDENCE: Level 3, associative study.

Segmental foot and ankle kinematic differences between rectus, planus, and cavus foot types.

The presence of multiple foot types has been used to explain the variability of foot structure observed among healthy adults. These foot types were determined by specific static morphologic features and included rectus (well aligned hindfoot/forefoot), planus (low arched), and cavus (high arched) foot types. Unique biomechanical characteristics of these foot types have been identified but reported differences in segmental foot kinematics among them has been inconsistent due to differences in neutral referencing and evaluation of only select discrete variables. This study used the radiographically-indexed Milwaukee Foot Model to evaluate differences in segmental foot kinematics among healthy adults with rectus, planus, and cavus feet based on the true bony alignment between segments. Based on the definitions of the individual foot types and due to conflicting results in previous literature, the primary study outcome was peak coronal hindfoot position during stance phase. Additionally, locally weighted regression smoothing with alpha-adjusted serial t-test analysis (LAAST) was used to compare these foot types across the entire gait cycle. Average peak hindfoot inversion was -1.6° ± 5.1°, 6.7° ± 3.5°, and 13.6° ± 4.6°, for the Planus, Rectus, and Cavus Groups, respectively. There were significant differences among all comparisons. Differences were observed between the Rectus and Planus Groups and Cavus and Planus Groups throughout the gait cycle. Additionally, the Planus Group had a premature peak velocity toward coronal varus and early transition toward valgus, likely due to a deficient windlass mechanism. This assessment of kinematic data across the gait cycle can help understand differences in dynamic foot function among foot types.

Long-Term Results of Surgical Treatment of Valenti Procedures for Hallux Rigidus: A Minimum Ten-Year Follow-Up Retrospective Study.

Few studies reporting long-term results of surgical treatment of hallux rigidus have been published. The aim of this study is to assess the clinical outcome of Valenti procedures in a series of patients with hallux limitus/rigidus with a minimum 10-year follow-up time. We retrospectively evaluated 38 patients (40 feet) who underwent a Valenti procedure with a mean follow-up of 132 ± 19.6 (range 114 to 184) months. All patients were clinically reassessed on the basis of the evaluation of pain (visual analogue scale), function (American Orthopaedic Foot and Ankle Society Hallux Metatarsophalangeal-Interphalangeal Scale Assessment and Foot & Ankle Disability Index), and subjective satisfaction. The scores before and after treatment, obtained from clinical recordings and clinical evaluation during the last follow-up visits, were compared. We found significant improvement of the mean values of the visual analogue score (p < .0001), Foot & Ankle Disability Index (p < .0001), and American Orthopaedic Foot and Ankle Society Hallux Metatarsophalangeal-Interphalangeal Scale Assessment (p < .0001) during the latest follow-up visits. The results suggest that the Valenti technique represents a safe, reproducible surgical procedure that allows satisfying long-term results. The few reported complications were essentially the progressive worsening of the joint stiffness, but no sesamoiditis, metatarsal overload, secondary surgeries, or failures were documented.

Prefabricated foot orthoses compared to a placebo intervention for the treatment of chronic nonspecific low back pain: a study protocol for a randomised controlled trial.

BACKGROUND: Prefabricated foot orthoses are used to treat chronic nonspecific low back pain, however their effectiveness and potential mechanism of action is unclear. The primary aims of the study are to investigate the effectiveness of prefabricated foot orthotic devices for reducing pain and improving function in people with chronic nonspecific low back pain over 52 weeks. METHODS: This study is a participant and assessor blinded, parallel-group, superiority randomised (1:1) controlled trial. The study will recruit 60 participants aged 18 to 65 years with chronic nonspecific low back pain. Participants will undergo randomisation to a control group (The Back Book) or an intervention group (prefabricated foot orthoses and The Back Book). The primary outcome measures will be change in pain and function from baseline to 12 (primary time point), 26, and 52 weeks. Secondary outcome measures include: gluteus medius muscle activity and transversus abdominis muscle thickness from baseline to 12 weeks, physical activity over 12, 26, and 52 weeks, and correlation between foot type and change in measures of pain and function. Number of hours per day and week that the prefabricated orthoses are worn, as well as, adverse events will be self-reported by participants. Data will be analysed using the intention-to-treat principle. DISCUSSION: This trial will primarily evaluate the effectiveness of prefabricated foot orthotic devices for reducing pain and improving function in people with chronic nonspecific low back pain over 52 weeks. It is expected that this study will provide clinicians and researchers with an understanding of the role that prefabricated foot orthoses may have in the treatment of chronic nonspecific low back pain and a potential mechanism of action, and whether foot type influences the outcome. TRIAL REGISTRATION: ACTRN12618001298202.

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

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

Study on the foot shape characteristics of the elderly in China.

BACKGROUND: With aging, the feet of the elderly above 60 years old in China present degenerative changes, deformities, and diseases, which significantly affect their daily activities. OBJECTIVES: The authors aimed to study the morphological characteristics of the feet and identify the foot type according to size (length and width) and defect characteristics of elderly feet in China. METHODS: A convenient sample of 1000 subjects above 60 years old was recruited mainly in the regions of Shanghai, Shaanxi, Henan, Hebei, and Sichuan in China. Foot images were collected, and 800 (male 398, female 402) valid questionnaires were recovered. A total of 800 elderly subjects as the test group were invited to measure their foot sizes by means of a Footprint Collector (Tong Yuan Tang Health Management Limited, Qingdao in Shandong province). The foot type of the elderly was compared with that of the general adult Chinese population as the control group using the t-test for independent samples. RESULTS: Hallux valgus (46.9%) and flat foot (50.0%) were the most common foot shape deformities. The most frequent foot diseases were foot scaling (91.2%) and calluses (96.3%). The medial width of the first metatarsal-toe joint of the elderly was significantly higher (elderly female, 44.95±4.86mm; elderly male, 48.55±4.94mm) than that of the general adult population (adult female, 40.18±3.43mm; adult male, 43.22±3.20mm) (p<0.01). CONCLUSION: The foot length of the elderly was not significantly different from that of the general adult Chinese population. The width of the first metatarsal-toe joint in the forefoot of the elderly was significantly higher than that of the general adult Chinese population, which was consistent with the result that a high proportion of elderly subjects presented hallux valgus.

An explorative investigation of functional differences in plantar center of pressure of four foot types using sample entropy method.

In the study of biomechanics of different foot types, temporal or spatial parameters derived from plantar pressure are often used. However, there is no comparative study of complexity and regularity of the center of pressure (CoP) during the stance phase among pes valgus, pes cavus, hallux valgus and normal foot. We aim to analyze whether CoP sample entropy characteristics differ among these four foot types. In our experiment participated 40 subjects with normal feet, 40 with pes cavus, 19 with pes valgus and 36 with hallux valgus. A Footscan® system was used to collect CoP data. We used sample entropy to quantify several parameters of the investigated four foot types. These are the displacement in medial-lateral (M/L) and anterior-posterior (A/P) directions, as well as the vertical ground reaction force of CoP during the stance phase. To fully examine the potential of the sample entropy method for quantification of CoP components, we provide results for two cases: calculating the sample entropy of normalized CoP components, as well as calculating it using the raw data of CoP components. We also explored what are the optimal values of parameters m (the matching length) and r (the tolerance range) when calculating the sample entropy of CoP data obtained during the stance phases. According to statistical results, some factors significantly influenced the sample entropy of CoP components. The sample entropies of non-normalized A/P values for the left foot, as well as for the right foot, were different between the normal foot and pes valgus, and between the normal foot and hallux valgus. The sample entropy of normalized M/L displacement of the right foot was different between the normal foot and pes cavus. The measured variable for A/P and M/L displacements could serve for the study of foot function.