Arch Height Index Research Articles

Associations of muscle volume of individual human plantar intrinsic foot muscles with morphological profiles of the foot.

Human plantar intrinsic foot muscles consist of 10 muscles that originate and insert within the sole of the foot. It is known that the anatomical cross-sectional area (ACSA) and muscle thickness of two plantar intrinsic foot muscles, the flexor hallucis brevis (FHB) and abductor hallucis (ABH), associate with morphological parameters of the foot, such as total and truncated foot length and navicular height. However, it is unclear how the size for each of the plantar intrinsic foot muscles associates with various morphological profiles of the foot. This study aimed to elucidate this subject. By using magnetic resonance imaging (MRI), serial images of the right foot were obtained in 13 young adult men without foot deformities. From the obtained MR images, ACSA for each of the individual plantar intrinsic foot muscles was analyzed along the foot length, and then its muscle volume (MV) was calculated. The analyzed muscles were the abductor digiti minimi (ABDM), ABH, adductor hallucis oblique head (ADDH-OH), adductor hallucis transverse head (ADDH-TH), flexor digitorum brevis (FDB), FHB, and quadratus plantae (QP). Furthermore, MV of the whole plantar intrinsic foot muscle (WHOLE) was defined as the total MVs of all the analyzed muscles. As morphological parameters, total foot length, truncated foot length, forefoot width, ball circumference, instep circumference, navicular height, great toe eversion angle, and little toe inversion angle were measured using a laser three-dimensional foot scanner in standing and sitting conditions. In addition, navicular drop (ND) and normalized truncated navicular height (NTNH) were also calculated as medial longitudinal arch (MLA) height indices. The MV of WHOLE was significantly associated with the forefoot width, ball circumference, and instep circumference (r=0.647-0.711, p=0.006-0.013). Positive correlations were found between the forefoot width and MV of FHB, FDB, and QP (r=0.564-0.653, p=0.015-0.045), between the ball circumference and MV of QP (r=0.559, p=0.047), between the instep circumference and MV of FHB (r=0.609, p=0.027), and between the little toe inversion angle and MV of QP (r=0.570, p=0.042). The MVs of ABH, ABDM, and ADDH-OH were not significantly correlated with any morphological parameters of the foot. Similarly, no significant correlations were found between MV of each muscle and either of the MLA height indices (ND and NTNH). Thus, the current results indicate that forefoot width and circumferential parameters (instep and ball circumference), not MLA height, associate with the size of the whole plantar intrinsic foot muscles, especially those specialized in toe flexion (FHB, FDB, and QP).

Biomechanical Characteristics of the Support Leg During Side-Foot Kicking in Soccer Players With Chronic Ankle Instability

Background:Chronic ankle instability (CAI) in soccer players can increase the risk of recurrent ankle varus sprains and damage the articular surface of the ankle joint, thus increasing the risk of osteoarthritis. It is important to understand the biomechanical characteristics of the support leg during kicking in soccer players with CAI.Purpose/Hypothesis:The purpose of this study was to clarify the kinematics of the kicking motion of soccer players with CAI. It was hypothesized that at the point before ball contact when the support leg makes flat-foot contact with the ground, soccer players with CAI will land with ankle inversion in the support leg during a side-foot kick compared with players without CAI.Study Design:Controlled laboratory study.Methods:The study cohort included 19 male college soccer players (mean age, 20.5 ± 0.9 years) with greater than 8 years of soccer experience who were recruited from August 2019 to March 2020. Of these athletes, 10 had CAI and 9 had no CAI in the support leg, as diagnosed according to the Cumberland Ankle Instability Tool. Kinematic data for the trunk, hip, knee, and foot of the support leg during a side-foot kick were obtained using a 3-dimensional, motion-analysis system. The Mann-Whitney U test or Student t test was selected to identify differences in variables between the CAI and non-CAI groups.Results:There were no significant differences in physical characteristics between the CAI and non-CAI groups. At the point when the support leg made flat-foot contact with the ground, the players with CAI had more eversion of the hindfoot with respect to the tibia (-28.3° ± 12.1° vs -13.9° ± 14.2°; P = .03), a more varus alignment of the knee (26.0° ± 10.7° vs 13.7° ± 10.5°; P = .03), and a lower arch height index (0.210 ± 0.161 vs 0.233 ± 0.214; P = .046) compared with non-CAI players.Conclusion:Significant differences between players with and without CAI were seen in the support leg kinematics at flat-foot contact with the ground during the kicking cycle.Clinical Relevance:The biomechanical alignment of the support leg during a side-foot kick in players with CAI may reflect a subconscious attempt to avoid inversion of the foot and further ankle sprains.

Plantar fasciitis injury status influences foot mechanics during running

BackgroundThe biomechanical factors related to plantar fasciitis are not well understood. A history of injury is considered a risk factor for subsequent injury, but it is unknown if differences in mechanics exist before, during, and after injury. This study compared gait mechanics among individuals with plantar fasciitis, resolved plantar fasciitis, and uninjured controls. MethodsThirty male and female runners were divided into three groups: 1) plantar fasciitis (n = 10, age 43 ± 11 years); 2) resolved plantar fasciitis (n = 10, age 43 ± 13 years); and 3) control (n = 10, age 38 ± 11 years). Participants ran at preferred velocity and 3.3 m/s while kinematics and kinetics were collected. Variables of interest include vertical loading rate, foot, ankle, knee, and hip kinematics, arch height index, arch rigidity index, and arch drop. Group differences were analyzed at each velocity using one-way analysis of variance. FindingsThe plantar fasciitis group exhibited less forefoot extension (P = 0.02), more midfoot inversion (P < 0.01), and more midfoot extension (P < 0.01) than the resolved plantar fasciitis group. Foot mechanics in controls did not differ. Sagittal knee range of motion was greater in the plantar fasciitis group than resolved or control (P = 0.01). No other variables were significantly different among groups. InterpretationThe plantar fasciitis group exhibited dynamic foot mechanics which suggest a lower, more flexible arch compared to the resolved group, although static measures of foot structure and ankle motion did not differ. The differences between these groups indicate that the motion of the forefoot and midfoot during gait are important to consider for plantar fasciitis.

Effect of Arch Height Flexibility in Individuals With Flatfoot on Abductor Hallucis Muscle Activity and Medial Longitudinal Arch Angle During Short Foot Exercises

Flatfoot presents decreased medial longitudinal arch (MLA), and such foot deformity involves intrinsic foot muscles dysfunction. Flatfoot can be classified into flexible and stiff types according to arch height flexibility (AHF). Short foot exercise (SFE) is an intrinsic foot muscle strengthening exercise, which is reportedly effective against flatfoot. However, its effectiveness against flexible or stiff types in flatfoot is unclear. We examined the effect of AHF in individuals with flatfoot during abductor hallucis muscle (AbH) activity and medial longitudinal arch during SFE. Foot alignment was assessed using the arch height index during standing, and individuals with flatfoot (N=16) were recruited. The AbH activity and MLA angle during SFE while maintaining single-leg standing were assessed. The relationship between AHF and AbH activity and between AHF and MLA angle ratio was analyzed using correlation coefficients. Additional correlations between AHF and AbH activity were observed with the outliers removed. There were no correlations between AHF and AbH muscle activity and between AHF and MLA angle ratio. However, with the 2 outliers removed, moderate correlations between AHF and AbH activity were significant (r=0.64, p = .01). AbH activity during SFE increased in individuals with flatfoot for high AHF (flexible type). Thus, SFE may be more effective for individuals with flatfoot having a high AHF. These findings may be helpful when making decisions for surgery and rehabilitation.

The influence of age and gender on normalized foot arch height of Korean children and adolescents: a cross-sectional study

Both the non-normalized and normalized arch height have been used to compare foot arch height among children. This study measured changes in foot dimensions, including length and the non-normalized and normalized arch height, among children and adolescents aged 8–19 years. Three-dimensional scanning data of 1451 children and adolescents were obtained. Four normalized arch height indices were calculated: the navicular height/total foot length, navicular height/instep length, instep height/total foot length and instep height/instep length. The current study found a significant positive relationship between foot length and non-normalized arch height. The normalized arch height increased linearly up to the age of 16 years. The proportion of pes planus also decreased with age. Current findings shed light on normative foot development in children and adolescents.

Peritalar Subluxation: A Key Finding for Both Cavovarus and Flatfoot Deformities

Category:Hindfoot; Midfoot/ForefootIntroduction/Purpose:Peritalar subluxation in both the talonavicular and subtalar joints has been described as characteristic markers for adult acquired flatfoot deformity (AAFD). However, no study has reported these changes in in cavovarus deformity, and we postulated that peritalar subluxation would apply to both the AAFD as well as the cavovarus foot deformity but in different directions using the same markers. Furthermore, the use of calcaneocuboid (CC) joint subluxation as an additional marker for peritalar subluxation has never been investigated in either flatfoot or cavovarus deformities. This study used three dimensional images of weightbearing cone beam computed tomography (WBCT) to evaluate the alignment of the peritalar joints in feet with normal, varus and valgus hindfoot alignment.Methods:WBCT scan images and medical charts of 400 patients were retrospectively reviewed. Thirty cavovarus and 15 flexible AAFD feet were chosen as the study groups. Fifteen feet without deformities and arthritis, a history of trauma or surgery in both the hindfoot and ankle were chosen as controls. Hindfoot moment arm (HMA), Foot and ankle offset (FAO) were used to assess hindfoot alignment. Middle facet subluxation (MFS), talonavicular joint coverage angle (TNCA), and calcaneocuboid joint subluxation (CCS) were used as markers of peritalar subluxation. The talocalcaneal (Kite's) angle in the axial plane was used to demonstrate the relative position between the talus and the calcaneus. The arch height index in the sagittal plane was used to assess medial arch height. Positive was used to reflect lateral subluxations while negative for medial ones. Correlations between HMA, FAO and each of the above three peritalar subluxation parameters were assessed by bivariate linear regression.Results:Patients in both the cavovarus and the AAFD groups showed totally different hindfoot alignment, peritalar subluxation and the height of the medial arch compared to the control group. In the order of Cavovarus, AAFD, and Control, the mean HMA- CR values were -20.43mm, 14.02mm, and 0.03mm, respectively; HMA-WBCT values were -6.34mm, 15.75 mm, and 3.19 mm; FAO values were -11.17%, 7.42%, and 2.63%; TNCA were -16.8 degrees, 22.11, and 6.45; The MFS values were -17%, 42%, and 22%; CCS values were -21% (IQR=-35%,-0.17%), -7% (IQR=-11%, 0) and 0 (IQR=-4%, 5%); The Kite's angles were 22.19 degrees, 34.27 degrees, and 28.06 degrees; The arch height index values were 0.25, 0.71, and 0.44. There was a statistically significant difference among the three groups in all the above parameters. There was a strong positive linear correlation between each parameter of the peritalar subluxation marks with both hindfoot moment arm and FAO.Conclusion:This is the first study to bring the concept of peritalar subluxation to cavovarus deformity assessment, proving that peritalar subluxation is a key characteristic in both flatfoot and cavovarus foot deformities. The two deformities are pathologically completely different, and as expected, markers of peritalar subluxation were in opposite directions. The use of calcaneocuboid joint subluxation as additional marker of perisubtalar subluxation is novel to assess both deformities. The findings of this study will provide useful guidelines for future clinical evaluation and decision making in treating patients with either varus or valgus hindfoot deformities.

Hindfoot Varus Deformity: An Essential but Easily Neglected Pathological Change in Müller-Weiss Disease

Category:Hindfoot; Midfoot/Forefoot; OtherIntroduction/Purpose:The key pathology of Müller-Weiss Disease (MWD) is fragmentation of the lateral pole of the navicular which leads to lateral rotation of the talar head, inversion of the subtalar joint, and eventually collapse of the medial arch with a paradoxical flatfoot deformity since the varus heel persists. Treatment for MWD should be based on an understanding of this unusual hind and midfoot deformity in order to achieve ideal outcomes. For years however, some authors have treated MWD as a flatfoot deformity instead of correction of the varus heel. This study used weightbearing CT (WBCT) images to demonstrate the structural and alignment changes of the hindfoot and medial arch in patients with MWD compared to those of controls and patients with adult acquired flatfoot deformity (AAFD).Methods:Twelve patients with 17 feet from two medical centers with a clinical diagnosis of MWD were retrospectively reviewed. Ten feet with flexible AAFD were chosen as the flatfoot control group. Ten feet without deformity, arthritis, a history of trauma, or prior surgical history in the foot and ankle were chosen as normal controls. The hindfoot moment arm (HMA), foot and ankle offset (FAO), middle facet subluxation (MFS), talonavicular joint coverage angle (TNCA), and the percentage of calcaneocuboid joint subluxation (CCS) measured on WBCT were used to assess the alignment of the hindfoot and peritalar joints. The arch height index was used to assess the height of the medial arch. Positive was used to reflect lateral subluxations and negative was for the medial ones. ANOVA test were used to compare data among the three groups with a normal distribution, while Wilcoxon test were used for non normal distribution.Results:According to WBCT analysis, patients with MWD showed totally different hindfoot alignment and peritalar subluxation characteristics compared to the AAFD and the normal control groups. In the order of MWD, AAFD and control, the mean HMA values were -3.44 mm, 15.75 mm, and 3.19 mm, FAO values were -0.72%, 7.42%, and 2.63%. TNCA values were -7.18, 22.11, and 11.37; MFS values were 14%, 45%, and 23%; CCS values were -0.19, 0 and -0.04. The arch height index values were 0.46, 0.45, and 0.58. There was statistically significant difference among the three groups in all the above parameters except the middle facet subluxation and fifth metatarsal medial cuneiform height ratios between the MWD group and the normal controls.Conclusion:This study confirmed that hindfoot varus is a typical feature of MWD. And this is the first study to demonstrate that peritalar subluxation is an important marker. With lateral rotation of the talar head, the subtalar joint is driven into varus, with medial subluxation of both the middle facet and the calcaneocuboid joint, resulting in peritalar subluxation opposite to that of AAFD. No significant difference between the medial arch of the MWD group and the controls was present. In conclusion, structural changes of the midfoot and hindfoot totally different from the characteristics of AAFD are present in MWD.

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 variablesResults: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.

Comparison of Gait parameters among the adults (18-24) with and without flatfoot – A Cross sectional study

Background: Flat foot is a common deformity in which the medial longitudinal arch is eliminated or reduced, subtalar joint is pronated and the calcaneus achieves valgus position under- weight bearing conditions. Any feet disorder can alter the biomechanics of the entire lower limb. The aim of the study was to compare the gait parameters (Cadence, stride length, step length and pace) among the adults (18-24) with and without flat foot. Methodology: It was a cross-sectional study with 3 months duration. Total 56 young adults (18-24) with and without flatfoot were recruited with purposive sampling method. the categorization of the type of arch using Arch-Height index. The Outcome measures were Gait parameters (cadence, distance walked in one minute, speed, step length, stride length) which were noted by pedometer of Smart watch and stride length, step length by using formula using cadence and distance findings. Result: Comparison analysis was done by using unpaired t-test. On comparison of various Gait parameters between normal and flat foot individuals such as cadence (p=0.7), distance walked in one minute (p= 0.96), speed (p=0.78), step length (p= 0.98), stride length (p= 0.92), there was no significant difference between two groups. Conclusion: The study concludes that there is no difference in gait parameters between flatfoot and normal foot.

Comparison of foot posture and foot muscle morphology between lifesaver athletes and healthy adults

ABSTRACT This study aimed to compare the foot muscle morphology and foot posture between healthy adults and lifesavers in sandy beach sports. The participants included 15 lifesaver athletes and 15 healthy adults. Using a non-contact three-dimensional foot measurement device, the foot length, width, and arch height of the right foot were measured while standing and sitting without back support, and the transverse arch length ratio and arch height index were subsequently calculated. Muscle cross-sectional area was measured using an ultrasound imaging device. Muscle cross-sectional areas, arch height, foot width, arch height index, and transverse arch length ratio were larger in the lifesaver than in the healthy adult group. Lifesavers had higher arches and more developed intrinsic and extrinsic muscles than healthy adults. Performing physical activity while barefoot on sandy beaches may effectively develop the foot intrinsic and extrinsic muscles and raise the arch.

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

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. 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). 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). 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.

Do Arch Height and Arch Stiffness Relate to Physical Performance in Adult Men?

Foot arch plays an important role in bearing body weight, absorbing ground reaction forces and maintaining balance, and its structure and function are bound to have a profound effect on physical activities and sports. Arch height and arch stiffness are 2 factors that represent the structure and function of the arch. Therefore, the purpose of this study was to explore the associations of arch height and arch stiffness with physical performance. A total of 56 men (aged 49.00 ± 7.95 years, mean body mass index [BMI] 26.80 ± 3.75 kg/m2) participated in this study. A 3-dimensional laser scanner was employed to obtain foot structure information of each participant, from which the arch height index (AHI) and arch stiffness index (ASI) were computed. Physical performance measures including agility, power, and proprioception were tested in a random order. The results indicated that the stepping forward and backward and vertical jump that represent agility and force respectively were negatively and significantly associated with AHI (r = -0.27, p = .045; r = -0.35, p = .009). When adjusted for age and BMI, only height of vertical jump was found to be correlated significantly with AHI (r = -0.29, p = .040); while no significant relationships were observed between physical performance measures and ASI. Multivariate linear regression analysis showed that AHI, age, and BMI can effectively predict the height of vertical jump. This study demonstrates that there is a negative correlation between arch height and muscle power of lower limbs in adult men.

Does QUICK TAPE Offer Comparable Support and Off-loading as Low-Dye Taping?

Low-Dye taping is commonly used to manage foot pathologies and pain. Precut one-piece QUICK TAPE was designed to facilitate taping. However, no study to date has demonstrated that QUICK TAPE offers similar support and off-loading as traditional taping. This pilot study compared the performance of QUICK TAPE and low-Dye taping in 20 healthy participants (40 feet) with moderate-to-severe pes planus. Study participants completed arch height index (AHI), dynamic plantar assessment with a plantar pressure measurement system, and subjective rating in three conditions: barefoot, low-Dye, and QUICK TAPE. The order of test conditions was randomized for each participant, and the taping was applied to both feet based on a standard method. A generalized estimating equation with an identity link function was used to examine differences across test conditions while accounting for potential dependence in bilateral data. Participants stood with a significantly greater AHI (P = .007) when either taping was applied compared with barefoot. Participants also demonstrated significantly different plantar loading when walking with both tapings versus barefoot. Both tapings yielded reduced force-time integral (FTI) in the medial and lateral forefoot and increased FTI under toes. Unlike previous studies, however, no lateralization of plantar pressure was observed with either taping. Participants ranked both tapings more supportive than barefoot. Most participants (77.8%) ranked low-Dye least comfortable, and 55.6% preferred QUICK TAPE over low-Dye. Additional studies are needed to examine the clinical utility of QUICK TAPE in individuals with foot pathologies such as heel pain syndrome and metatarsalgia.

Comparison of the degree of pes planovalgus and muscle mass of the ankle joint and foot muscles between children with Down syndrome and children with typical development

We aimed to compare the degree of pes planovalgus and muscle mass of the ankle joint and foot muscles between children with Down syndrome (DS) and children with typical development (TD). We also examined the association of the degree of pes planovalgus with muscle mass of the ankle joint and foot muscles in children with DS and children with TD. The subjects were 24 children with TD (control [CTR] group) and 23 children with DS (DS group). To assess pes planovalgus, the Arch Height Index (AHI) in the standing position was measured. Muscle thickness of the ankle joint and foot muscles was measured using an ultrasound imaging device. The AHI and thickness of the soleus and tibialis posterior muscles were significantly lower in the DS group than those in the CTR group. The thickness of the flexor digitorum longus muscle was significantly greater in the DS group than that in the CTR group. Stepwise regression analysis revealed that the thickness of the flexor digitorum longus muscle was a significant and independent factor of the AHI in children comprising the CTR and DS groups. The thickness of the flexor digitorum longus muscle increased with decreasing AHI. The results of this study suggest that the AHI and muscle mass of the soleus and tibialis posterior muscles decrease, while muscle mass of the flexor digitorum longus muscle increases in children with DS. The results also indicate that decreased AHI is associated with increased muscle mass of the flexor digitorum longus muscle in children.

Relationship between forward propulsion and foot motion during gait in healthy young adults

The foot contributes to propulsion and postural stability function by changing its morphology during walking through the truss/windlass mechanisms. We quantified the truss mechanism regarding foot stiffness and the windlass mechanism regarding the movement coordination between the foot arch and metatarsophalangeal (MTP) joint. We aimed to clarify the relationship of these mechanisms with propulsive force and static foot alignment. Forty-eight healthy young adults participated and walked at a comfortable speed. The ground reaction force (GRF), ankle power, and sagittal plane motion of the foot arch and MTP joint were recorded using a three-dimensional motion analysis system. The vertical GRF and foot arch motion were used to quantify foot stiffness as the truss coefficient, and the foot arch and first MTP joint were used to quantify movement coordination as the windlass coefficient. The Foot Posture Index (FPI) and arch height index (AHI) were used to assess static foot alignment. A canonical correlation analysis was performed using the foot- and gait-related index group, and then a single-correlation analysis was performed. The canonical correlation analysis showed that a composite variable consisting of FPI, AHI, and the truss coefficient was related to the anterior GRF (A-GRF) and ankle power. The truss coefficient was positively correlated with A-GRF and ankle power, whereas the windlass coefficient was positively correlated with ankle power. Therefore, the truss and windlass coefficients can be used as indices to evaluate foot function, suggesting that maintaining foot stiffness and foot arch coordination with the first MTP joint is important for propulsion.

Comparison of Pedal Arch Anatomy in First and Second Grade Elementary School Students in Denpasar with Flat Foot and Normal Foot

Flat foot is a condition which pedal arch is absent. This condition is count physiological if found in infants and children at a certain age due to incomplete development of bone structure and surrounding tissue. Flat foot is a common condition in pediatrics, which affects about 20% to 30% of the world's population. The prevalence of flat foot will decrease concomitantly with age. At two years old, 94% of children experience flat foot and only 4% at ten years old experience this condition. Most children will show complete and normal development of the sole foot at 12 years old. Pedal arch is one of the important parts that affect the anatomical structure of the lower limb and foot biomechanical. This study aims to compare the anatomical structure of the pedal arch in patients with flat foot and normal foot from Arch Height Index (AHI), Plantar Arch Index, Calcaneal Pitch Angle (CP), Talo-Horizontal Angle (TH), and Meary’s talus-first metatarsal (T-1MT). This study is an analytical study with a cross sectional approach using a sample of 30 elementary school students in Denpasar. The data obtained were analyzed using descriptive analysis and comparative test. In this study, we found significant differences in the plantar arch index and calcaneal pitch angle between students with normal foot and flat foot. We also found no significant differences in AHI, T-1MT and TH between students with normal foot and flat foot.

Validity of two-dimensional analysis using a tablet computer for estimation of foot arch height during walking.

[Purpose] To examine the validity of two-dimensional analysis using a tablet computer for the estimation of arch height during walking by comparing it with a motion capture system and static foot alignment screenings. [Participants and Methods] Fourteen healthy males and 15 healthy females participated in this study. The arch height of the right foot while walking was simultaneously measured using a tablet computer and motion capture system. Dynamic foot alignment, including arch height, at the mid-stance and pre-swing phases was calculated from the kinematic data measured using the tablet computer and motion analysis system. Static foot alignment was also assessed by screening tests including arch height index and foot posture index. [Results] Arch height measured using a tablet computer showed a significant high correlation with that measured using the motion capture system at the mid-stance and pre-swing phases. Arch height index showed a significant moderate correlation with arch height measured using the motion capture system at the mid-stance phase. Meanwhile, foot posture index showed no relationship with arch height measured by the motion capture system. [Conclusion] These results demonstrate the high validity of dynamic foot analysis using a tablet computer for the estimation of arch height during walking. Such gait analysis can be effective for assessing dynamic foot alignment in clinical practice.

3D printing technology applied to orthosis manufacturing: narrative review.

Recently, three-dimensional (3D) printing technology has gradually been applied to the field of orthoses. This narrative review aimed to investigate the effect of 3D printed orthoses compared to conventional orthoses (non-3D printed orthoses). We searched MEDLINE for articles published up to July 27, 2020, and the main search phrases for identifying related articles were "3D printed orthosis", "3D printed orthoses", "3D printed braces", "3D printed splints", "3D printing orthosis", "3D printed orthoses", "3D printing braces" and "3D printing splints". We included articles that applied 3D printed orthoses to patients or healthy participants and excluded those not written in English, conference abstracts or presentations, and reviews. A total of 237 papers were identified, and qualifications were evaluated based on the title, abstract, and full text. A total of 22 articles were finally included in the analysis. The 3D printed orthoses showed similar or superior effects on biomechanical parameters and kinematic parameters such as wrist-hand function, wrist spasticity, arch height index, foot plantar pressure, and joint range of motion (ROM). In addition, 3D printed orthoses had high satisfaction and comfort compared to conventional orthoses. We believe that 3D printed orthoses can replace conventional ones, and they are expected to gain more popularity in the future.

Increased Contact Time and Strength Deficits in Runners With Exercise-Related Lower Leg Pain.

Exercise-related lower leg pain (ERLLP) is common in runners. To compare biomechanical (kinematic, kinetic, and spatiotemporal) measures obtained from wearable sensors as well as lower extremity alignment, range of motion, and strength during running between runners with and those without ERLLP. Case-control study. Field and laboratory. Of 32 young adults who had been running regularly (>10 mi [16 km] per week) for ≥3 months, 16 had ERLLP for ≥2 weeks and 16 were healthy control participants. Both field and laboratory measures were collected at the initial visit. The laboratory measures consisted of alignment (arch height index, foot posture index, navicular drop, tibial torsion, Q-angle, and hip anteversion), range of motion (great toe, ankle, knee, and hip), and strength. Participants then completed a 1.67-mi (2.69-km) run along a predetermined route to calibrate the RunScribe devices. The RunScribe wearable sensors collected kinematic (pronation excursion and maximum pronation velocity), kinetic (impact g and braking g), and spatiotemporal (stride length, step length, contact time, stride pace, and flight ratio) measures. Participants then wore the sensors during at least 3 training runs in the next week. The ERLLP group had a slower stride pace than the healthy group, which was accounted for as a covariate in subsequent analyses. The ERLLP group had a longer contact time during the stance phase of running (mean difference [MD] = 18.00 ± 8.27 milliseconds) and decreased stride length (MD = -0.11 ± 0.05 m) than the control group. For the clinical measures, the ERLLP group demonstrated increased range of motion for great-toe flexion (MD = 13.9 ± 4.6°) and ankle eversion (MD = 6.3 ± 2.7°) and decreased strength for ankle inversion (MD = -0.49 ± 0.23 N/kg), ankle eversion (MD = -0.57 ± 0.27 N/kg), and hip flexion (MD = -0.99 ± 0.39 N/kg). The ERLLP group exhibited a longer contact time and decreased stride length during running as well as strength deficits at the ankle and hip. Gait retraining and lower extremity strengthening may be warranted as clinical interventions in runners with ERLLP.

Calcaneus height is a key morphological factor of sprint performance in sprinters

This study examined the relationships between the foot bone morphologies and sprint performance in sprinters. Foot images in 56 male sprinters obtained using magnetic resonance imaging. The relative lengths of the forefoot bones of the big and second toes, which were calculated as total lengths of the forefoot bones for each toe normalized to the foot length, correlated significantly with personal best 100-m sprint time (r = − 0.293 and − 0.459, both Ps < 0.05). The relative lengths of the rearfoot talus and calcaneus normalized to the foot length also correlated significantly with the sprint performance (r = − 0.378 and − 0.496, both Ps < 0.05). Furthermore, the relative height of the calcaneus, but not the talus, normalized to body height correlated significantly with sprint performance (r = − 0.690, P < 0.001). Additionally, the relative calcaneus height correlated significantly with the foot arch height index (r = 0.420, P = 0.001), and the foot arch height index correlated significantly with sprint performance (r = − 0.517, P < 0.001). These findings suggest that the taller calcaneus may be a key morphological factor for achieving superior sprint performance, potentially via modeling the longer forefoot and rearfoot bones and functional foot morphology in sprinters.