Longitudinal Arch Research Articles

Association of Flat Feet with Knee Moments and Western Ontario and McMaster Universities Arthritis Index in Knee Osteoarthritis

Introduction: Flat feet are prevalent among individuals with medial compartment knee osteoarthritis (KOA), showing a correlation with elevated knee pain and cartilage degeneration. This study investigates the relationship between calcaneal eversion angle (CEA) and medial longitudinal arch angle (MLAA) with knee kinetics and pain. Materials and Methods: This analytical observational study included 30 volunteers with moderate KOA. The Vicon motion analysis system and two synchronized force plates were employed to capture level walking and the static standing position to measure CEA and MLAA. The study assessed the first and second peaks of the knee adduction moment, knee adduction moment impulse, peak knee flexion moment, and the peak knee flexion angle at heel strike (PKFA-HS). The Western Ontario and McMaster Universities arthritis index (WOMAC) pain and physical function were evaluated. Results: A significant positive correlation was found between CEA and the knee pain sub-score (Pearson correlation [PC]=0.446, P=0.011) and WOMAC total score (PC=0.363, P=0.049). Additionally, a significant negative correlation was observed between CEA and peak knee flexion moment/PKFA-HS (PC=-0.418, P=0.022, and PC=-0.479, P=0.001, respectively). The results also indicated a negative significant correlation between MLAA and WOMAC pain sub-score (PC=-0.389, P=0.034). Conclusion: Increased CEA and decreased MLAA are associated with elevated WOMAC pain sub-score and decreased PKFA-HS in individuals with moderate KOA. Addressing flat feet should be considered in KOA management to enhance pain relief and functional outcomes

Advancing Adult-Acquired Flatfoot Deformity Treatment: Enhanced Biomechanical Support Through Graphene Oxide-Integrated Bioengineered Grafts Tested In Silico

Adult-Acquired Flatfoot Deformity (AAFD) is a progressive orthopedic condition causing the collapse of the foot’s medial longitudinal arch, often linked with injuries to the plantar arch’s passive stabilizers, such as the spring ligament (SL) and plantar fascia. Conventional treatment typically involves replacing the SL with synthetic material grafts, which, while providing mechanical support, lack the biological compatibility of native ligaments. In response to this shortcoming, our study developed an electrospun, twisted polymeric graft made of polycaprolactone (PCL) and type B gelatin (GT), enhanced with graphene oxide (GO), a two-dimensional nanomaterial, to bolster biomechanical attributes. The addition of GO aimed to match the native ligamentous tissue’s mechanical strength, with the PCL-GT-GO 2.0% blend demonstrating an optimal Young’s modulus of 240.75 MPa. Furthermore, the graft showcased excellent biocompatibility, evidenced by non-hemolytic reactions, suitable wettability and favorable platelet aggregation—essential features for promoting cell adhesion and proliferation. An MTT assay revealed cell viability exceeding 80% after 48 h of exposure, highlighting the potential of the graft as a regenerative scaffold for affected ligaments. Computational modeling of the human foot across various AAFD stages assessed the graft’s in situ performance, with the PCL-GT-OG 2.0% graft efficiently preventing plantar arch collapse and offering hindfoot pronator support. Our study, based on in silico simulations, suggests that this bioengineered graft holds significant promise as an alternative treatment in AAFD surgery, marking a leap forward in the integration of advanced materials science for enhanced patient care.

The Effect of Towel Toe Curl Exercise and Tibialis Posterior Strengthening on Dynamic Balance of Flatfoot Patients at SD Negeri 104242 Lubuk Pakam

Background: Improper use of the foot can cause problems when walking and even endanger a person's health. The arch of the foot helps withstand impact pressure and provides stability when standing or walking. Flatfoot is a deformity related to the foot, such as medial longitudinal arch disorders of the foot, valgus deformity of the heel, and forefoot abduction. The exercise methods that can be given to overcome flatfoot are Towel toe curl exercise and tibialis posterior strengthening. Purpose: to improve foot function by strengthening the intrinsic muscles of the foot. While tibialis posterior strengthening exercise is to strengthen the tibialis posterior muscle, which is part of the extrinsic muscle. Research method: This type of research is quantitative with a one group pre-test and post-test design. Data analysis using paired sample t-test. The sample of this study were children at SD Negeri 104242 Lubuk Pakam who suffered from flatfoot with a total of 22 samples. The intervention given was towel toe curl and tibialis posterior strengthening 3 times a week for 4 weeks with a total of 12 actions. Before the dynamic balance intervention, respondents were measured first (pretest) with the Y Balance Test (YBT) and re-measured after the intervention (Posttest). Results and discussion: The results of the paired sample t-test obtained a significant value (p) of 0.000, greater than the alpha value (a) (0.000 <0.05), meaning that there is a significant effect of towel toe curl exercises and tibialis posterior strengthening on improving dynamic balance in flatfoot children. Conclusion: Based on the results of the study, it can be concluded that towel toe curl exercises and tibialis posterior strengthening can be one of the training methods that can be applied to overcome dynamic balance disorders in flatfoot sufferers

Effects of Toe-Strengthening Exercises on Medial Longitudinal Arch Height, Muscle Stiffness, and Functional Movement

Background: Prolonged training in combat boots can place significant stress on the medial longitudinal arch, potentially leading to lower-extremity muscle stiffness and an increased risk of injury. This study assessed the impact of toe-strengthening exercises on improving the lower-extremity function and functional movement in cadets undergoing training. Methods: Forty junior cadets (mean age: 22.6 years) participated in this study. The measurements included the medial longitudinal arch height, lower-extremity muscle stiffness, functional movement, and leg length. Results: Cadets who performed the toe exercises demonstrated improved lower-extremity muscle stiffness and functional movement performance (hurdle step, p = 0.010; rotary stability, p = 0.001). A significant correlation was observed between the exercise group and time (tibialis right, p = 0.008; tibialis left, p = 0.028). Conclusions: This study highlighted the potential of toe-strengthening exercises to enhance the lower-extremity function and reduce the risk of injury among cadets. However, challenges in identifying the medical history, past injuries, and specific areas of pain for each cadet were noted. These findings support the implementation of targeted toe exercises in military training programs to prevent injuries.

Treatment Options for Plantar Fasciitis: Surgical Release vs. Conservative Therapy

Introduction Plantar fasciitis is one of the most common reasons for visits to orthopedic clinics. This tendinopathy can cause medial heel pain, stiffness, and tenderness on the plantar surface of the foot. Both conservative and surgical methods are employed in its treatment. Aim The aim of this study is to evaluate selected conservative treatment methods, such as stretching, the use of orthotic insoles, splints, injections, extracorporeal shockwave therapy, and taping, as well as surgical treatment options. The study presents a comparison of these methods in terms of their effectiveness, advantages, and disadvantages. State of Knowledge The plantar fascia is a stiff, connective tissue structure extending along the plantar surface of the foot. Biomechanical load on the fascia, which supports the medial longitudinal arch, can lead to degenerative changes that underlie plantar fasciitis. Symptoms include pain, particularly in the mornings and late evenings, which intensifies with palpation of the heel area. Summary (Conclusions) Conservative treatments for plantar fasciitis are effective in 90% of patients. There are no studies that conclusively demonstrate the superiority of one treatment method over another. Thus, the choice of therapy should be tailored to the patient's lifestyle, activity level, and financial capability. Surgical intervention is necessary in cases of chronic plantar fasciitis which remains resistant to conservative treatments.

AVALIAÇÃO DA TÉCNICA DE ARTRORRISE SUBTALAR NO TRATAMENTO DO PÉ PLANO VALGO FLEXÍVEL PEDIÁTRICO: UMA REVISÃO DE LITERATURA

Introduction: Flexible flatfoot is characterized by loss of the medial longitudinal arch and subtalar eversion and is a prevalent orthopedic condition among pediatric patients. Subtalar arthroereisis has emerged as an effective surgical option for the correction of this deformity, without the need for fusion of the subtalar joint or osteotomies. The aim of this study is analyze the available evidence on the efficacy and safety of subtalar arthroereisis in the treatment of flexible pediatric flatfoot. Methodology: This is an extended literature review study through bibliographic research using the terms subtalar, arthroereisis, and flexible flatfoot. The inclusion criteria included original articles published in the last 10 years. Results: Seven articles were selected to compose the review database. The studies addressed skeletally immature patients and evaluated the results of subtalar arthroereisis. Based on our articles, the results demonstrate a significant reduction in pain and adequate correction of deformities, regardless of the type of implant used – be it absorbable or non-absorbable. The procedure has a relatively low complication profile, which reinforces its reliability as a viable alternative for pediatric patients. The most common complications, such as implant loosening, incomplete correction, tarsal bone pain and screw breakage, were observed in a minority of cases. Conclusion: Subtalar arthroereisis presents an effective and safe surgical option for the treatment of flexible flatfoot foot in children.

Contribution of the plantar fascia and long plantar ligaments to the stability of the longitudinal arch of the foot

The contribution of the Plantar Fascia (PF) and Long Plantar Ligament (LPL), two ligaments extending from the hindfoot to the forefoot, to arch stability has been studied in the past using in vivo, in vitro, and in silico methodologies. In silico studies were based on one single model obtained from one single subject and did not account for the known inter-subject morphological and biomechanical variations. In the present study, we developed computational dynamic models of nine different legs obtained from nine different individuals to evaluate the role of the LPL and PF in arch support, accounting for biological differences between subjects. These models were validated by comparing the simulation results against experimental results from the corresponding cadaver legs. After validation, we simulated body weight conditions for each model by applying a vertical load to the tibia, starting from zero and increasing linearly to 720 N. Kinematic and dynamic parameters, including the variation of the medial arch angle and of the navicular height, as well as the passive forces developed by the LPL and PF, were used to evaluate the contribution of these ligaments to arch support under body weight. The results indicate that a total collapse of the medial longitudinal arch occurred only when both the LPL and PF were absent, but a stable arch was maintained when either one of these two ligament structures were present. The results varied significantly among the specific models, highlighting the importance of using multiple models to account for inter-subject morphological differences.

ArchCheck Tool: An Innovative Instrument to Measure Arch Height

BACKGROUND Pes planus, commonly known as flat foot is a deformity of the foot, characterized by loss of the medial longitudinal arch of the foot. There are several diagnostic methods available, such -as radiographs and digital footprint scanning techniques, that involve the usage of ink, dyes, and expensive instrumentation which may be harmful and not readily available at all time. The arch height may prove to be a user-friendly, portable, and affordable means of grading the foot. However, no tools were found during the search for review of literature. Hence, a need for a tool to measure the arch height and further give standard range of the arch height for flat feet and non-flat feet was identified. OBJECTIVE To design a tool and further provide values to differentiate flatfoot and non-flatfoot using arch height as a measurement tool. RELEVANCE The instrument was designed to quantify arch height and values to differentiate flatfoot and non-flatfoot are provided by comparison with Chippaux Smirak Index (CSI). METHOD The study evaluated the medial longitudinal arches of 30 individuals (60 feet) using static footprints and arch height measurement with tool. The footprints were classified into flatfoot and non-flatfoot using CSI. Data was subjected to appropriate statistical analysis. RESULTS The range of medial longitudinal arch height between 15-21mm in sitting position and 13-19 mm in standing position identified with non-flat foot, while the range of medial longitudinal arch height between 10-14 mm in sitting position and 8-12 mm in standing position identified with flat foot when compared with CSI. These findings suggest that the tool can be used effectively to measure the medial longitudinal arch height and differentiate between individuals with flat foot and non-flat foot. CONCLUSION The study concludes that the tool is effective in measuring the medial longitudinal arch height and can be used to differentiate between individuals with flat foot and non-flat foot. Designers of the tool would like to name the tool as ArchCheck Tool.

Correlation of Radiological and Pedobarographic Evaluations in the Presence of Foot Sole Pain

Objective: One of the reasons for foot pain is the changes in the structure of the medial longitudinal arch. Assessment of medial longitudinal arch height is often made with foot radiographs and pedobarographic measurements. The relationship between these methods in the presence of foot sole pain has not been examined yet. This study aims to investigate the relationship among these measurement methods in adults with foot sole pain. Materials and Methods: 60 adults with foot sole pain were included in this study. The talohorizontal, talocalcaneal, talo1.metatarsal, and calcaneal inclination angles were measured in the lateral weight bearing foot radiographs. The arch index was calculated in static, dynamic pedobarographic measurements. The agreement of radiological and pedographic measurements among themselves and with each other was determined. Results: The mean age of 60 participants was 45.32 ±13.64. Agreement among foot classifications of radiologic measurements was poor Gwet’s agreement coefficient =-0.198 with a 95% confidence interval (-0.315,-0.080); percent agreement = 0.167 with a 95% confidence interval (0.099,0.234) and Kappa =-0.047 with a 95% confidence interval (-0.083,-0.01) were found. The agreement between pedobarographic classifications was fair Gwet’s agreement coefficient =0.486 with a 95% confidence interval (0.355,0.617); percent agreement =0.65 with 95% confidence interval (0.563,0.737) and Kappa=0.453 with a 95% confidence interval (0.324,0.583) were found. Among radiological measurements, the calcaneal inclination angle showed the highest coefficients of agreement with pedobarographic measurements. The extent of its agreement was fair. Conclusion: Pedobarography is a simple, reliable, inexpensive, and noninvasive method. The calcaneal inclination angle which is used in radiological imaging can give an idea about the height of the medial longitudinal arch.

3D Analysis of Metatarsal Torsion by Computed Tomography in Normal, Hallux Valgus, and Hallux Rigidus Feet.

One factor contributing to rotational deformity of the first metatarsal in hallux valgus is torsion of the metatarsal itself. Hallux rigidus also involves reduction of the longitudinal arch, but metatarsal torsion has not been discussed. We hypothesized that metatarsal torsion may be a morphologic change unique to hallux valgus. We compared 3-dimensional (3D) torsion of the first to fifth metatarsals between feet with hallux valgus, feet with hallux rigidus, and healthy control feet to investigate differences in the effects on pathologic conditions. Participants were women of East Asian descent. There were 16, 16, and 14 feet in the control, hallux valgus, and hallux rigidus groups, respectively. One randomly selected control foot was designated as the reference foot. For comparison, nonweightbearing computed tomography images of the metatarsals were reconstructed in 3D, and the proximal and distal areas were superimposed on the reference foot. Torsion angle was defined as the rotational angle of the distal part of the articular axis relative to the proximal area. In the hallux valgus group, correlations of torsion angle with hallux valgus angle and intermetatarsal angle were calculated. The hallux valgus group had greater average pronation torsion in the first metatarsal than the control group and hallux rigidus group (11 and 13 degrees greater, respectively, P < .01). No significant differences were observed for the second to fifth metatarsals (P > .05). There was no significant correlation with hallux valgus angle or first-second intermetatarsal angle in the hallux valgus group (P > .05). Hallux valgus feet had pronation deformities in the first metatarsals not observed in control or hallux rigidus feet, meaning that torsion toward pronation (eversion) in the first metatarsal was unique to hallux valgus. Improved surgical correction to diminish pronation may be necessary in patients with hallux valgus patients because of first metatarsal pronation in the first tarsometatarsal to normalize mechanical first-ray alignment.Level of Evidence: Level III, case-control stud.

Influence of medial longitudinal arch flexibility on lower limb joint coupling coordination and gait impulse

BackgroundA causal link exists between structural differences in the foot and alterations in the lower limb biomechanics, which might predispose an individual to develop characteristic musculoskeletal disorders. Research questionThis study aimed to determine how the foot structural characteristics, as represented by the medial longitudinal arch flexibility, affect lower limb joint coupling coordination and anterior-posterior ground reaction impulses (GRIs) during walking and running. MethodsFollowing the calculation of arch height flexibility, a total of fifty-four physically active males were grouped and completed gait experiments to collect kinematic and kinetic data synchronously. Inter-joint coordination and variability were calculated from the angle-angle plots of knee-hip, ankle-knee, and metatarsophalangeal (MTP)-ankle couplings based on an optimized vector coding technique. ResultsOur results indicate that coupling coordination of interest and its variability, as well as anterior-posterior GRIs, could potentially be influenced due to differences in arch height flexibility. Notably, the individuals with stiff arches exhibited significantly greater coordination variabilities during the early stance for both ankle-knee and MTP-ankle coordination yet significantly smaller for MTP-ankle coordination variabilities during the mid-stance phase. Furthermore, combining the statistical parametric mapping analysis results, the flexible arches experienced a greater proportion of GRIs in the anterior-posterior direction. SignificanceIn conclusion, these observations demonstrated that variations in arch flexibility led to differences in lower limb joint coordination variabilities and GRIs during gait. This fresh insight into inter-joint coordinative function may be useful for enhancing foot motion strategies based on arch structural characteristics.

Study of correlation between arches of foot and lower back pain in Eastern India

Background: Low back pain is one of the most common disorders of the musculoskeletal system, leading to impaired function and decreased quality of life in many patients. Foot arch alterations may lead to structural changes and/or affect its load distribution. It should be noted that even slight elevations of the foot’s medial longitudinal arch above the norm may lead to changes in load and pressure distribution. Hence, it becomes important to find the relationship between low back pain and altered foot arch indices leading to improper body balance. Aims and Objectives: The aims and objectives of the study are to find any correlation between lower back pain and an altered foot arch index in the Eastern Indian population. Materials and Methods: A total of 60 subjects aged 20–40 years with varying degrees of low back pain were selected. Low back pain scores of the subjects were found using modified oswestry low back pain disability questionnaire. Footprints in standing position using ink were taken on graph paper and the foot arch indices were calculated. Results: 54.16% of the male and 36.11% of female participants had low arched feet, 20.83% of male and 52.78% of female participants had normal arched feet, and 25% of male and 11.11% of female participants had high arched feet with varying degrees of low back pain. 77.42% of the participants with minimal disability due to low back pain were having normal arched feet, 71.43% of the participants with moderate disability due to low back pain were having low arched feet, and 100% of the participants with severe disability due to low back pain were having either high or low arched feet. Conclusion: This study showed that people having either low or high arched feet are at an increased risk of developing acute or chronic low back pain at some stage in their lives. Knowledge of this risk factor might even help people to choose appropriate occupations in the future.

Physical characteristics inducing Sever's disease in junior gymnasts

ObjectiveThis prospective cohort study aimed to determine characteristics contributing to the development of Sever's disease in junior gymnasts. MethodsThis study included 74 limbs from 37 junior gymnasts. The Baseline demographic data, flexibility measurements, foot alignments, trunk function tests, and functional balancing tests were used for evaluation. The incidence of Sever's disease among this cohort was assessed for six months after the first evaluations. We categorized those diagnosed by medical specialists as having Sever's disease into a Sever's disease group, while those with no foot pain or other diagnosed pathologies were in a no-symptom group. ResultsThe Junior gymnasts with Sever's disease had a lower arch height ratio and lower anterior star excursion balance test values. ConclusionsSever's disease in junior gymnasts may be potentially prevented through using a medial longitudinal arch support and/or undertaking dynamic postural balance training.

Biomechanical effect between conventional and 3-dimensional printed customized foot orthoses on medial longitudinal arch support and rearfoot angle in adults with flexible flatfeet.

Customized foot orthoses are used to treat flexible flatfoot regarding medial longitudinal arch (MLA) support, alignment correction, and pain management. Recently, 3-dimensional (3D) printing orthosis has become the focus of discussion regarding function and manufacturing. We aimed to investigate differences in biomechanical effects between flat insole (Flat), conventional foot orthosis (Cinsole), and 3D printed foot orthosis (3Dinsole) use on MLA support and rearfoot alignment during walking in adult flexible flatfeet. Twelve men with flexible flatfoot were recruited. Data were collected and analyzed using a Vicon motion capture system under 3 trial conditions: Flat and >1 month after using Cinsole and 3Dinsole. Repeated-measures analysis of variance with Bonferroni post hoc tests was used to compare kinematics variables, foot pain, and satisfaction. Dynamic navicular drop significantly reduced with the use of the Cinsole and 3Dinsole compared with Flat (P < 0.001; ηp2 = 0.65). The maximum rearfoot eversion angle with the use of the Cinsole and 3Dinsole significantly reduced from Flat (P < 0.001; ηp2 = 0.56). Foot pain score significantly decreased after using foot orthoses; satisfaction between Cinsole and 3Dinsole was not significantly different. Thus, Cinsole and 3Dinsole are effective alternative treatments of MLA support and rearfoot alignment in adults with flexible flatfoot. 3D printing is a future technology with potential to replace conventional production methods. However, material characteristics, design, and manufacturing process can affect treatment outcomes; hence, our results may not represent all variations of 3D printed foot orthoses.

Use of postural insoles to correct dynamic knee valgus in youth soccer players: a randomized, controlled, double-blind clinical trial

Introduction: Altered alignment of the lower limb promotes dynamic knee valgus (DKV), the foot pronacion is among the injuries associated with DKV and is less studied, as well as their treatment through postural insoles which generate elevation of the medial longitudinal plantar arch of the foot. Objective: To analyze the effect of using a postural insole in correcting DKV in young soccer players. Materials and Method: The following parameters were analyzed: the frontal plane projection angle (FPPA) of the knee by video capture during the lateral step down and the center of pressure excursion index (CPEI) by Computerized Baropodometric Analysis. The sample was randomly divided into 2 groups: Corrective Postural Insole Group (CPIg) and Placebo Postural Insole Group (PPIg). Results: The repeated measures Anova showed significant differences with an increase between the means obtained in the FPPA (P=0.002) and CPEI (P=0.034) assessments of the PPIg group. The means of the evaluations in the CPIg were significant, with an increase for the FPPA (P=0.003), and not significant for the CPEI (P=0.793), but the Bonferroni adjustment showed a significant increase in the means of the FPPA between Ev1 x Ev3 (difference: 6.22º; P=0.001) in PPIg; and between Ev1 x Ev3 (difference: 6.86º; P=0.016) and Ev2 x Ev3 (difference: 4.14º; P=0.015) in the CPIg. Conclusion: The findings allow us to conclude that the use of postural insoles with 5º corrective shims was not effective in reducing DKV, since the PPIg (which did not use corrective shims) also showed the same increase in FPPA.

Plantar Pressure Characteristics with Foot Postures and Balance Abilities in Indigenous Taiwanese: A Preliminary Exploration.

BACKGROUND Although Indigenous Taiwanese are generally known for having excellent athleticism and balance abilities, the correlation between foot characteristics and balance abilities has rarely been discussed. This study aimed to explore the characteristics of plantar pressure profiles associated with foot posture and balance abilities among Indigenous Taiwanese. MATERIAL AND METHODS We recruited 165 Indigenous college students and 183 healthy age-matched students. Bipedal static plantar pressure distributions (PPDs) with arch index (AI) and centers of gravity balance were examined using the JC Mat. Foot posture was determined by estimating the rearfoot postural alignment. RESULTS Indigenous Taiwanese in the study generally had low-arched feet with increased plantar loads at the medial (left: 1.21±0.43%; right: 1.20±0.46%) and lateral longitudinal arches (left: 24.51±5.26%; right: 24.45±6.64) (P<0.01) and the medial metatarsals (left: 21.78±3.81%; right: 22.19±3.91) (P<0.01). Footprint images illustrated pronounced cuboid and navicular collapses. Performances of balance abilities (left: 49.53±4.38%; right: 50.47±4.38) (P<0.01) and rearfoot postural angles (left: 1.37±1.25°; right: 1.32±1.17°) (P<0.05) were better than those of controls. CONCLUSIONS The feet in Indigenous Taiwanese had low arches and higher plantar loads at the medial and lateral longitudinal arches and medial metatarsals, while their centers of gravity were symmetrical and rearfoot posture was normal. These results may facilitate further studies on the relationship between foot characteristics, potential athleticism, and musculoskeletal injuries in Indigenous Taiwanese.

Local and non-local effects (on the posterior chain) of four weeks of foot exercises: a randomized controlled trial

This study investigated the local, remote, and contralateral effects of a four-week intrinsic foot muscle exercise intervention in recreationally active participants on foot parameters, flexibility, and performance of the posterior chain (PC). Twenty-eight healthy participants (12f, 16m) were randomly assigned to a control group or performed 2 × 6 min of foot exercises twice daily unilaterally at least five days/week for four weeks. At baseline (M1), after the intervention (M2), and after a four-week wash-out period (M3), we assessed bilateral Foot Posture Index-6, medial longitudinal arch mobility, single-leg stance balance, range of motion (ROM) (first metatarsophalangeal joint and ankle), and flexibility and performance of the PC. The FPI-6 score changes over time differed significantly between groups for both legs, improving by 26% in the trained- (p < .001) and 11% in the untrained leg (p = .02) in the intervention group from M1 to M2. Improvements were maintained at M3 for the trained leg (p = .02). Ankle range of motion and balance of the trained leg improved from M1 to M2, yet only became significant at M3 (ROM: p = .02; balance: p = .007). The other parameters did not change significantly. A four-week foot exercise intervention might have local but no remote effects in healthy young adults.German Clinical Trial Register (DRKS00027923) (24/08/2022).

Muscular Activation Levels of Subjects with Low Medial Longitudinal Arch During Single-Leg Squat and Single-Leg Balancing Exercises on Surfaces of Different Hardness.

The primary aim of this study is to examine the effect of the stiffness of rehabilitation material on muscle activation in individuals with low medial longitudinal arch. The secondary aim is to compare the effects of single-leg balancing and single-leg squat exercises on the activation of the muscles around the ankle in the same individuals. Twelve individuals with low medial longitudinal arch and 18 healthy control participants were included. Participants were asked to perform the single-leg balance and single-leg squat exercises on Theraband stability trainers of three different stiffness levels. Activation of the peroneus longus, peroneus brevis, tibialis anterior, medial and lateral gastrocnemius muscles during exercises was evaluated by surface electromyography. The single-leg balancing exercise performed on soft and very soft ground was more effective than single-leg squat in increasing the activation of the lateral gastrocnemius muscle in participants with a low medial longitudinal arch. It was determined that performing single-leg squat exercise on a very soft surface instead of hard ground caused more muscular activation in the peroneus brevis, tibialis anterior, and medial gastrocnemius in the same individuals. The exercise progression to be applied on different surfaces to increase the activation of the muscles around the ankle in individuals with a low medial longitudinal arch and in healthy individuals without a low medial longitudinal arch was different.

Foot torsional stiffness exhibits gender differences but shows no correlation with medial longitudinal arch height

Although foot mobility tends to be greater in females, sex-based differences in foot torsional stiffness have not been investigated. It is also unclear whether assessing the medial longitudinal arch (MLA) height reflects foot torsional stiffness. This study included 52 healthy adults (26 females and 26 males) with an average age of 24.6 years. The arch height index was used to assess MLA height. To calculate foot torsional stiffness, a custom-built torque meter and a three-dimensional motion analysis system were employed. The forefoot was passively rotated from the maximum eversion to the maximum inversion at a rate of 2.5°/s. The forefoot’s resistance torque and rotation angle relative to the rearfoot were recorded. Foot torsional stiffness was defined by establishing the slope of the regression line from 10° eversion to 10° inversion of the torque–angle curve, with the slope subsequently normalized by body weight. Gender differences in foot torsional stiffness and the correlation between MLA height and foot torsional stiffness were investigated. Foot torsional stiffness was significantly lower in females than in males (0.00237 ± 0.00061Nm/°･kg vs 0.00368 ± 0.00136 Nm/°･kg, p < 0.001, effect size: r = 0.65, statistical power = 0.99). MLA height was not significantly different between sexes. No significant correlations were found between foot torsional stiffness and MLA height in either sex. Foot torsional stiffness and MLA height reflect different mechanical properties of the foot, emphasizing the need for individual assessment and consideration of sex differences.

Predictors of flatfoot in 11–12-year olds: a longitudinal cohort study

BackgroundThe structures around the navicular bones, which constitute the medial longitudinal arch, develop by 10 years of age. While navicular bone height is often emphasized in the assessment of flatfoot, three-dimensional (3D) evaluations, including those of structural parameters during inversion, have rarely been investigated. If the development of flatfoot during the growth process could be predicted, appropriate interventions could be implemented. Therefore, in this longitudinal cohort study, we developed a system, utilizing smartphones, to measure the 3D structure of the foot, performed a longitudinal analysis of changes in midfoot structures in 124 children aged 9–12 years, and identified factors influencing the height of the navicular bone. The foot skeletal structure was measured using a 3D system.ResultsOver 2 years, foot length and instep height increased during development, while navicular height decreased. The 25th percentile of the instep height ratio and navicular height ratio at ages 9–10 years did not exceed those at ages 11–12 years, with percentages of 17.9% and 71.6%, respectively, for boys, and 15.8% and 49.1%, respectively, for girls. As the quartiles of the second toe–heel–navicular angle (SHN angle) increased at ages 9–10 years, the axis of the bone distance (ABD) and SHN angles at ages 11–12 years also increased, resulting in a decrease in the navicular height ratio. A significant inverse correlation was found between changes in SHN angle and navicular height ratio. These findings indicate that the navicular bone rotation of the midfoot is a predictor of the descent of the navicular bone.ConclusionsThis study revealed that some children exhibit decreases in navicular bone height with growth. As a distinct feature, the inversion of the navicular bone promotes flattening of the midfoot. Thus, this study provides insights into changes in midfoot development in children and provides an effective evaluation index.