Influence of the menstrual cycle on static and dynamic kinematics of the foot medial longitudinal arch

BACKGROUND

In women, the laxity of the plantar fascia increases during the ovulation phase of the menstrual cycle. Although it is possible that this increased laxity results in a decreased height of the foot in the medial longitudinal arch and exacerbates symptoms of several overuse injuries of the lower extremity, the influence of the menstrual cycle on static and dynamic kinematics of the medial longitudinal arch is unclear. The purpose of this study was to confirm that the medial longitudinal arch height during static standing, gait, and landing decrease during the menstrual cycle ovulation phase.

METHODS

Participants in this study were 16 female college students with normal menstrual cycles and 16 male college students. Navicular height in the static standing position was measured using a three-dimensional foot scanner. Kinematics of the medial longitudinal arch during gait and landing were measured using a three-dimensional motion capture system to determine the navicular height at initial contact, minimal navicular height, and dynamic navicular drop. In all measurements, female participants were tested twice during the course of one complete menstrual cycle: once during the follicular phase and once during the ovulation phase. Male participants were tested twice with an interval of ≥1 week and <2 weeks.

RESULTS

In women, navicular height in the static standing position significantly decreased during the ovulation phase compared with follicular phase (mean difference [95% confidence interval] = 2.1 [0.9-3.4] mm; p = 0.002), whereas men showed no statistical difference between the first and second measurements. In both men and women, no statistical differences were identified for the dynamic medial longitudinal arch kinematics measured during gait and landing.

CONCLUSIONS

Navicular height in the static standing position slightly decreased during the ovulation phase.

Morphological and mechanical characteristics of the intrinsic and extrinsic foot muscles under loading in individuals with flat feet

BACKGROUND

The intrinsic and extrinsic foot softtissue structures that apply force and support the medial longitudinal arch (MLA) have been implicated in the development of flat feet. However, the relationship between the changes in MLA height under increasing load and the morphological and mechanical properties of individual intrinsic and extrinsic foot soft tissue structures is not fully understood.

RESEARCH QUESTION

To examine the morphological and mechanical characteristics of the foot soft tissue structures in flat feet when subjected to loading.

METHODS

This study consisted of two studies focusing on the extrinsic foot muscles (10 normal feet/11 flat feet) and intrinsic foot muscles (14 normal feet/13 flat feet). Images of the extrinsic and intrinsic foot muscles and plantar fascia (PF) under 10%, 50%, and 90% body weight conditions were obtained using ultrasound-based shear-wave elastography.

RESULTS

The cross-sectional area (CSA) of the peroneus brevis was larger in the flat-foot group than in the normal-foot group under all loading conditions. The CSAs of the intrinsic foot muscles (abductor hallucis, flexor digitorum brevis, and quadratus plantae) and thickness of the PF in the flat-foot group decreased significantly with increasing load. As for mechanical characteristics, the stiffness of the flexor digitorum longus and abductor hallucis was higher in the flat-foot group than in the normal group under high loading conditions. In addition, flat feet with greater flexibility tended to exhibit a greater decrease in PF thickness and smaller increase in stiffness.

SIGNIFICANCE

Excessive stretching of the intrinsic foot muscles and PF occurs in flat feet, and excessive contraction of the flexor digitorum longus may counteract the excessive lowering of the foot arch. Therefore, it is necessary to promote the contraction of the intrinsic foot musculature in feet with greater flexibility of the MLA during loading.

Lower-limb dominance does not explain subject-specific foot kinematic asymmetries observed during walking and running

Studies of human locomotion have observed asymmetries in lower-limb kinematics, especially at the more distal joints. However, it is unclear whether these asymmetries are related to functional differences between the dominant and non-dominant limb. This study aimed to determine the effect of lower-limb dominance on foot kinematics during human locomotion. Range of motion for the metatarsophalangeal joint (MPJ) and medial longitudinal arch (MLA), as well as time duration of windlass mechanism engagement, were recorded from healthy young adults (N = 12) across a range of treadmill walking and running speeds. On the group level, there were no differences in MPJ or MLA range of motion, or windlass engagement timing, between the dominant and non-dominant limb (p > 0.05). While not explained by limb dominance, between-limb differences in MPJ and MLA ranges of motion were observed for individual participants on the order of ∼2-6°, which could be clinically relevant or impact interpretation of research data.

Muscle Architecture of Leg Muscles: Functional and Clinical Significance

Background

Architectural properties of the muscles are the prime predictors of functional attributes and force-generating capacity of the muscles. This data is vital for musculoskeletal modelling and selecting the appropriate muscle-tendon units for tendon transfers.Cadaveric data for architectural properties is the gold standard and primary input for musculoskeletal modelling. There is a paucity of these datasets, especially in the leg muscles.

Methods

Sixty muscles of the anterior and lateral compartments from twelve formalin-fixed lower limbs were studied for gross architecture, including the peculiar fibre arrangements and architectural properties of muscles. Muscle weight, muscle length, fibre length, pennation angle and sarcomere length were measured. Normalised fibre length, fibre length to muscle length ratio (FL/ML ratio), and the physiological cross-sectional area (PCSA) were calculated from the obtained data.

Results

Muscles displayed a combination of architectural strategies and were partly fusiform and partly pennate. The tibialis anterior and peroneus longus were the heaviest muscles in their respective compartments and showed more extensive origin from the nearby deep facial sheets.Long fibre length and less pennation angle were seen in muscles of the extensor compartment. Potential muscle power was highest in the tibialis anterior and peroneus longus and least in the extensor hallucis longus.

Conclusions

Arching of the foot and eversion are peculiar to humans and recent in evolution. Due to the functional demand of maintaining the medial longitudinal arch and eversion, the tibialis anterior and peroneus longus have more muscle weight and larger physiological cross-sectional area and are potentially more powerful.Extensor compartment muscles were architecturally more suited for excursions because of the long fibre length and less pennation angle.This study contributes baseline normative data for musculoskeletal modelling platforms and simulation tools - an emerging area in biomechanics and tendon transfers.

Kinetic coupling in distal foot joints during walking

BACKGROUND

Kinematic coupling between the first metatarsophalangeal (MTP) and midtarsal joints is evident during gait and other movement tasks, however kinetic foot coupling during walking has not been examined. Furthermore, contributing factors to foot coupling are still unclear. Therefore, the purpose of this study was to investigate kinematic and kinetic coupling within the foot by restricting MTP motion during overground walking. We hypothesized that when the MTP joint was prevented from fully extending, the midtarsal joint would achieve less peak motion and generate less positive work compared to walking with normal MTP motion.

METHODS

Twenty-six individuals participated in this randomized cross-over study. Using motion capture to track motion, participants walked at 1.3 m/s while wearing a brace that restricted MTP motion in a neutral (BR_NT) or extended (BR_EX) position. Additionally, participants walked while wearing the brace in a freely moveable setting (BR_UN) and with no brace (CON). A pressure/shear sensing device was used to capture forces under each foot segment. During stance, peak joint motion and work were calculated for the MTP and midtarsal joints using inverse dynamics. A series of ANOVAs and Holm post hoc tests were performed for all metrics (alpha = 0.05).

RESULTS

The brace successfully decreased peak MTP motion by 19% compared to BR_UN and CON. This was coupled with 9.8% less midtarsal motion. Kinetically, the work absorbed by the MTP joint (26-51%) and generated by the midtarsal joint (30-38%) were both less in BR_EX and BR_NT compared to BR_UN.

CONCLUSION

Implications and sources of coupling between the MTP and midtarsal joints are discussed within the context of center of pressure shifts and changes to segmental foot forces. Our results suggest that interventions aimed at modulating MTP negative work (such as footwear or assistive device design) should not ignore the midtarsal joint.

Using surface markers to describe the kinematics of the medial longitudinal arch

BACKGROUND

Static and dynamic assessment of the medial longitudinal arch (MLA) is an essential aspect for measuring foot function in both clinical and research fields. Despite this, most multi-segment foot models lack the ability to directly track the MLA. This study aimed to assess various methods of MLA assessment, through motion capture of surface markers on the foot during various activities.

METHODS

Thirty general population participants (mean age 20 years) without morphological alterations to their feet underwent gait analysis. Eight measures, each representing a unique definition of the MLA angle using either real only, or both real and floor-projected markers, were created. Participants performed tasks including standing, sitting, heel lift, Jack's test and walking, and had their Arch Height Index (AHI) measured using callipers. Multiple-criteria decision analysis (MCDA) with 10 criteria was utilised for selecting the optimal measure for dynamic and static MLA assessment.

RESULTS

In static tasks, the standing MLA angle was significantly greater in all measures but one when compared to sitting, Jack's test and heel lift. The MLA angle in Jack's test was significantly greater than in heel lift in all measures. Across the compared dynamic tasks, significant differences were noted in all measures except one for foot strike in comparison to 50% gait cycle. All MLA measures held significant inverse correlations with MLA measured from static and dynamic tasks. Based on MCDA criteria, a measure comprising the first metatarsal head, fifth metatarsal base, navicular and heel markers was deemed the best for MLA assessment.

SIGNIFICANCE

This study aligns with the current literature recommendations for the use of a navicular marker for characterising the MLA. It contrasts with previous recommendations and advocates against the use of projected markers in most situations.

Gluteus medius muscle strengthening exercise effects on medial longitudinal arch height in individuals with flexible flatfoot: a randomized controlled trial

This study aimed to compare the effects of 8 weeks of foot plus hip exercise to foot exercise alone on medial longitudinal arch (MLA) parameters; navicular drop (ND), arch height index (AHI), plantar pressure, static balance, and dynamic balance were measured at baseline, 4 weeks, and 8 weeks. A total of 52 healthy participants with bilateral flatfoot were randomly assigned into foot exercise (n=26) and foot plus hip exercise (n=26) group. At 4 weeks, the foot plus hip exercise group showed significantly less ND (P=0.002), plantar pressure at the medial forefoot (P=0.002), and mediolateral displacement (P=0.001) while showing a greater AHI (P=0.019) than the foot exercise group. At 8 weeks, there was also significantly less plantar pressure at the medial hindfoot (P=0.017) and less anteroposterior displacement (P=0.002) in the foot plus hip exercise group than in the foot exercise group. No significant differences between groups were found in dynamic balance. The addition of gluteus medius muscle strengthening exercise to foot exercise was more effective in supporting the MLA than performing foot exercise alone.

Does ankle arthrodesis induce satisfactory changes in the medial longitudinal arch height of the foot for severe varus ankle arthritis?

PURPOSE

We designed this study to determine how changes in coronal ankle alignment affect sagittal alignment of the foot. Specifically, we focused on the changes in medial longitudinal arch height, which could be reflected by the medial cuneiform height (MCH), Meary's angle, and calcaneal pitch angle (CPA).

METHODS

We retrospectively analyzed the radiographic findings of 37 patients who underwent open ankle arthrodesis without inframalleolar correction (such as first metatarsal dorsal closing wedge osteotomy, calcaneal osteotomies, tendon transfers, or tarsal joint arthrodesis) of severe varus ankle arthritis. The inclusion criterion was a pre-operative tibial axis to talar dome angle of 80 degrees or less. The enrolled patients were divided into two groups according to the post-operative decrease in MCH (≥ 2 mm or < 2 mm).

RESULTS

A post-operative MCH decrease of ≥ 2 mm was observed in 43.2% (16 patients). Although the degree of coronal ankle varus correction was similar, the decrease in the Meary's angle was significantly greater in the group with a post-operative MCH decrease of ≥ 2 mm than in those with < 2 mm (- 4.1 degrees vs. - 1.3 degrees, P = 0.01). The changes in CPA were not significantly different (P = 0.172).

CONCLUSION

Correction of ankle varus deformity via ankle arthrodesis could lead to a decrease in the medial longitudinal arch height in less than half of the enrolled patients. In these patients, a cavus component of the foot might be an important factor in determining a successful sagittal foot alignment change, while the CPA was maintained post-operatively.

Arch volume：a new method for medial longitudinal arch measurement

BACKGROUND

As a flexible and elastic structure, the dynamic morphometry of medial longitudinal arch remains to be an unresolved Issue for clinic. Here we introduce a new measurement named arch volume to describe the morphological changes of the medial longitudinal arch during weight-bearing and compare with present method for measuring MLA.

METHODS

64 healthy participants were enrolled. And the dynamic arch morphology was measured under four weight bearing status with navicular height, arch area and arch volume, respectively.

RESULTS

With the increase of weight loading, the flattening or slightly deformation of medial longitudinal arch was observed by all method (p<0.05). However, as a 3D indicator, arch volume not only showed higher sensitivity than other method, but also provide visualization of MLA during loading changing.

CONCLUSIONS

Compared with navicular height and arch area, arch volume has a significant advantage in describing arch morphological changes under different weight bearing status.

Comparison of each bundle of the spring ligament complex between the standing and supine positions: A multiposture magnetic resonance imaging study

BACKGROUND

The spring ligament complex (SLC) supports the medial longitudinal arch of the foot, particularly in standing. We evaluated posture-related changes in the thickness and length of the three SLC bundles and their histology.

METHODS

The thickness and length of the supramedial calcaneonavicular ligament (smCNL), medioplantar oblique calcaneonavicular ligament (mpoCNL), and inferoplantar calcaneonavicular ligament (iplCNL) were measured in the supine and standing positions, using a multiposture magnetic resonance imaging system, in 72 healthy adult feet. Histological examination was performed for 10 feet from five cadavers.

RESULTS

The smCNL thickness decreased and its length increased from the supine to the standing position (P < 0.001); no other posture-related effects were noted. Histologically, smCNL fibers overlapped along multiple directions while mpoCNL and iplCNL, fibers were oriented horizontally along the longitudinal axis and vertically along the short axis, respectively.

CONCLUSION

The complex, multidirectional, orientation of the smCNL allows an adaptive response to changes in loading.

The typically developing pediatric foot - The data of the 1744 children in China

BACKGROUND

The medial longitudinal arch (MLA) improves with age in childhood. However, it still causes parents to worry that children have flat feet. Due to the lack of a standard to quantitatively assess the arch development in kids at certain age, the pediatricians judge the flat feet by experience, causing many cases to be overtreated. The aim of this study was to plot the distribution of MLA parameters in children.

METHODS

Children without lower limb deformity and lower limb pain were recruited from 12 primary schools and kindergartens in Chongqing province-level city. Foot length (FL) and navicular height (NH) was measured manually, arch index (AI) and arch volume (AV) were measured with the Foot Plantar Scanner. Each parameter was measured in both weight-bearing and non-weight-bearing positions. Significant differences were also compared between the measurements of consecutive years.

RESULTS

This study was the first to use a three-dimensional laser surface scanner to measure the MLA parameters of children aged 3-12 years in China. 1744 children (871 girls, 873 boys) participated in this study. FL, NH, AI and AV varied significantly with age in both the weight-bearing and non-weight-bearing positions. These parameters have significant differences between the weighted and non-weighted positions (p < 0.05).

CONCLUSIONS

The age distribution characteristics of these parameters indicated that the MLA improves with age. The establishment of a developmental scale for the children's MLA is necessary.

The influence of the windlass mechanism on kinematic and kinetic foot joint coupling

Background

Previous research shows kinematic and kinetic coupling between the metatarsophalangeal (MTP) and midtarsal joints during gait. Studying the effects of MTP position as well as foot structure on this coupling may help determine to what extent foot coupling during dynamic and active movement is due to the windlass mechanism. This study’s purpose was to investigate the kinematic and kinetic foot coupling during controlled passive, active, and dynamic movements.

Methods

After arch height and flexibility were measured, participants performed four conditions: Seated Passive MTP Extension, Seated Active MTP Extension, Standing Passive MTP Extension, and Standing Active MTP Extension. Next, participants performed three heel raise conditions that manipulated the starting position of the MTP joint: Neutral, Toe Extension, and Toe Flexion. A multisegment foot model was created in Visual 3D and used to calculate ankle, midtarsal, and MTP joint kinematics and kinetics.

Results

Kinematic coupling (ratio of midtarsal to MTP angular displacement) was approximately six times greater in Neutral heel raises compared to Seated Passive MTP Extension, suggesting that the windlass only plays a small kinematic role in dynamic tasks. As the starting position of the MTP joint became increasingly extended during heel raises, the amount of negative work at the MTP joint and positive work at the midtarsal joint increased proportionally, while distal-to-hindfoot work remained unchanged. Correlations suggest that there is not a strong relationship between static arch height/flexibility and kinematic foot coupling.

Conclusions

Our results show that there is kinematic and kinetic coupling within the distal foot, but this coupling is attributed only in small measure to the windlass mechanism. Additional sources of coupling include foot muscles and elastic energy storage and return within ligaments and tendons. Furthermore, our results suggest that the plantar aponeurosis does not function as a rigid cable but likely has extensibility that affects the effectiveness of the windlass mechanism. Arch structure did not affect foot coupling, suggesting that static arch height or arch flexibility alone may not be adequate predictors of dynamic foot function.

Supplementary Information

The online version contains supplementary material available at 10.1186/s13047-022-00520-z.

Validity and inter-rater reliability of ankle motion observed during a single leg squat

BACKGROUND

The single leg squat (SLS) test is a clinical functional test commonly used to evaluate clinically aberrant movement patterns of the knee. The SLS could be an interesting option to analyze ankle control in the frontal plane during dynamic load analysis. However, to date, there are no studies that have analyzed the associations between the increased subtalar joint pronation by navicular drop (ND) test and ankle control with single leg squat (SLS_ankle) using a three-point scale. The purpose of this study was to evaluate the reliability of a clinical observation method to assess and determine the relationship between navicular drop (ND) and ankle control on the SLS_ankle score.

METHODS

A total of fifty-five healthy, physically active (31 females and 24 males) volunteers participated in this study. The degree of subtalar pronation was assessed through the ND test, and the ankle control was defined as the ankle displacement in the frontal plane during the SLS.

RESULTS

We found good intra-rater and inter-rater agreement during SLS_ankle, with Kappa values from 0.731 to 0.750. The relationship between the SLS_ankle and ND was significant ; the Spearman's rank correlation coefficient was 0.504 (p < 0.05).

CONCLUSIONS

The SLS_ankle score supplied the clinical practice with a reliable and valid alternative for quantifying foot mobility in comparison to the ND test.

Accuracy and correlation between skin-marker based and radiographic measurements of medial longitudinal arch deformation

Static and dynamic measurements of the medial longitudinal arch (MLA) in the foot are critical across different clinical and biomechanical research fields. While MLA deformation can be estimated using skin-markers for gait analysis, the current understanding of the correlates between skin-marker based models and radiographic measures of the MLA is limited. This study aimed at assessing the correlation and accuracy of skin-marker based measures of MLA deformation with respect to standard clinical X-ray based measures, used as reference. 20 asymptomatic subjects without morphological alterations of the foot volunteered in the study. A lateral X-ray of the right foot of each subject was taken in monopodalic upright posture with and without a metatarsophalangeal-joint dorsiflexing wedge. MLA angle was estimated in the two foot postures and during gait using 16 skin-marker based models, which were established according to the marker set of a validated multi-segment foot kinematic protocol. The error of each model in tracking MLA deformation was assessed and correlated with respect to standard radiographic measurements. Estimation of MLA deformation was highly affected by the skin-marker models. Skin-marker models using the marker on the navicular tuberosity as apex of the MLA angle showed the smallest errors (about 2 deg) and the largest correlations (R = 0.64-0.65; p < 0.05) with respect to the radiographic measurements. According to the outcome of this study, skin-marker based definitions of the MLA angle using the navicular tuberosity as apex of the arch may provide a more accurate estimation of MLA deformation with respect to that from radiographic measures.

Percutaneous plantar fasciotomy: radiological evolution of medial longitudinal arch and clinical results after one year

PURPOSE

Plantar fasciitis (PF) is the most common cause of plantar heel pain. Conservative treatment and corrections of risks factors are the first line of care. For the 10% of patients who do not respond to conservative treatment, surgical release can offer relief of symptoms. Due to the critical role of the PF in the function of the foot and its architectural maintenance, its surgical release could cause a collapse of the internal arch of the foot and an alteration of its function. With the hypothesis that an isolated percutaneous PF release may not lead to these alterations of the foot while providing relief to the patients, we evaluated the radiological evolution and clinical results of this surgery after one year.

MATERIAL AND METHOD

Between January 2013 and Augustus 2017, we conducted a single arm monocentric prospective study on 22 patients (25 feet) aged from 33 to 84 years, with plantar fasciitis and failure of conservative management who benefited a percutaneous total plantar fasciotomy through a plantar approach. The American Orthopedic Foot and Ankle Score (AOFAS) and the Djian-Annonier's angle were evaluated preoperatively and postoperatively.

RESULTS

Among the 22 patients, sixteen patients were female and six patients were male. Three patients (2 females and 1 male) for six feet were operated for bilateral plantar fasciitis. The mean pre-operative Djian-Annonier's angle was 117.6° (range 101-132.9°), and the mean post-operative angle was 119.3° (range 102-137°). There was no statistically significant difference in Djian-Annonier's angle before and after surgery. The mean pre-operative AOFAS was 42.8 (range 32-51). The scores at 15 days, six weeks, and three months show a gradual increase up to 89.9 in the results with significant differences between the groups (p < 0.05). There was no difference between the scores after three months.

CONCLUSION

Complete percutaneous plantar fasciotomy is simple and safe and allows a quick recovery to activity without impacting the MLA.

Effect of soft inflatable orthosis on the medial longitudinal arch in patients with flexible flatfoot deformity

BACKGROUND

Orthoses can stabilize the foot and restore the medial longitudinal arch for symptomatic flexible flatfoot. However, the effectiveness of orthoses remains controversial. The purpose of this study was to evaluate effectiveness of a customized soft inflatable orthosis on the medial longitudinal arch of flexible flatfoot patients under load.

METHODS

We obtained CT scans of the feet of 14 healthy volunteers and 14 patients with flexible flatfoot under non- and simulated weight-bearing conditions. Then CT scans under the same conditions were taken for patients with flexible flatfoot equipped with soft inflatable orthosis. Three-dimensional models of the medial longitudinal arch and hindfoot were constructed from CT images. The three-dimensional mobility of the medial longitudinal arch joints under load was compared between patients with flexible flatfoot equipped with soft inflatable orthosis or not.

FINDINGS

From non- to simulated weight-bearing condition, the eversion and dorsiflexion of the talocalcaneal joint, the eversion of the talonavicular joint, the abduction and dorsiflexion of the cuneonavicular joint, and the dorsiflexion of the first tarsometatarsal joint were significantly larger in patients with flexible flatfoot than healthy volunteers. The customized soft inflatable orthosis could reduce the eversion of the talonavicular joint and the eversion and dorsiflexion of the talocalcaneal joint.

INTERPRETATION

The soft inflatable orthosis is effective to improve medial longitudinal arch height and reduce excessive mobility of joints for flexible flatfoot deformity. The results of this study could provide evidence for the optimal orthosis design to treat flexible flatfoot in the future.

Semi-automatic measurements of foot morphological parameters from 3D plantar foot scans

Background

Foot healthcare research is focusing increasingly on personalized orthotic and prosthetic devices to address patient-specific morphology and ailments. Customization requires advanced 3D image processing tools to assess foot and leg geometrical parameters and alterations. The aim of this study is to present a new software for the measurement of the foot shape from 3D scans of the foot plantar surface.

Methods

A Kinect-based scanning device was used to acquire the 3D foot shape of 44 healthy subjects. A software was developed in Matlab to measure the foot main morphological parameters from foot scans. Principal Component Analysis was used to orientate the foot scans with respect to the same reference system. Accuracy, via percentage errors and Bland-Altman plots, and correlation of the software-based foot parameters were assessed against manual measurements. A normalized Arch Volume Index (nAVI) was proposed and correlated to the traditional Arch Index. Test-retest Intraclass Correlation Coefficient was used to assess the inter-session repeatability of foot measurements.

Results

The average percentage error between software and manual measurements was 1.2 ± 0.8% for foot length, 9.1 ± 3.7% for foot width, 22.3 ± 13.5% for arch height and 23.1 ± 12.7% for arch depth. Very strong correlations were observed for foot length (R = 0.97) and foot width (R = 0.83), and strong correlations for arch height (R = 0.62) and arch depth (R = 0.74). nAVI was negatively correlated to the Arch Index (R = -0.54). A small difference was found between software and manual measurements of foot length (Δ = 0.92 mm), a software overestimation of foot width (Δ = 8.6 mm) and underestimation of arch height (Δ = -1.4%) and arch depth (Δ = -11%). Moderate to excellent repeatability was observed for all measurements (0.67–0.99).

Conclusions

The present software appears capable to estimate the foot main morphological parameters without the need for skin markers or for identification of anatomical landmarks. Moreover, measurements are not affected by the foot orientation on the scanning device. The good accuracy and repeatability of measurements make the software a potentially useful operator-independent tool for the assessment of foot morphological alterations and for orthotics customization. nAVI may be used for a more realistic classification of foot types when 3D foot images are available.

The development of the medial longitudinal arch in the intrauterine period

In this study, we aimed to reveal whether the medial longitudinal arch is formed in the intrauterine period and the structural features of the medial longitudinal arch. The study was conducted on 146 feet of 73 fetuses (38 male, 35 female) aged between 15 and 40 weeks of gestation. The fetuses were grouped by trimesters. The footprints taken were photographed with a millimeter ruler, and the development of the medial longitudinal arch was examined on footprints based on the Clarke index, Chipaux-Smirak index, and Staheli index. In Clarke index and Staheli index, it was observed that the arch height was normalized in the transition from the second trimester to the third trimester, the arch decreased in the transition to full-term, and the rate of pes planus increased. All indices detected pes planus by 81.81% in the full-term period. The rate of pes planus determined according to Clarke index and Staheli index, especially in the third trimester period, was 6.94% and 11.11%, respectively. We have provided a perspective on how the development of the medial longitudinal arch is shaped in the intrauterine period. Based on the results of study, we consider that the data on the medial longitudinal arch, especially in the third trimester period, may be more significant. In the evaluations made from the footprints of premature infants in the intrauterine third trimester period in the future, a study, in which infants detected with pes planus can be followed up and the development of their medial longitudinal arch is evaluated, can be conducted.

Anomalous plantar intrinsic foot muscle attaching to the medial longitudinal arch: possible mechanism for medial nerve entrapment: a case report

Background

Muscular variations are potentially symptomatic and may complicate imaging interpretation. Intrinsic foot musculature and extrinsic tendon insertion variations are common. Distinct supernumerary muscles are rare. We report a novel anomalous intrinsic foot muscle on the medial longitudinal arch.

Case presentation

An accessory muscle was encountered on the medial arch of the right foot of a 78-year-old white male cadaver, between layers two and three of the foot intrinsics. It did not appear to be a slip or variant of a known foot muscle. This muscle consisted of two slips that ran transversely on the plantar aspect of the medial arch, crossing the medial transverse tarsal joint and attaching to the tuberosity of the navicular, the short and long plantar ligaments, and spring ligament.

Conclusions

The medial plantar vessels and nerve passed from deep to superficial between the two slips, and this suggests a possible location for medial nerve entrapment.

Navicular drop is negatively associated with flexor hallucis brevis thickness in community-dwelling older adults

BACKGROUND

Flatfoot is characterized as a lower longitudinal arch and is a common foot deformity in older adults. Foot intrinsic muscle dysfunction has been considered as one of the factors for a lower medial longitudinal arch. The objective of this study was to investigate the association of the navicular drop with the thickness of foot intrinsic muscles in older adults.

RESEARCH QUESTION

Which intrinsic muscle contributes most to support the medial longitudinal arch in older adults?

METHODS

We studied 88 community-dwelling older adults (mean age 74.2 ± 6.2 years). We measured the navicular height, the calcaneus inclination, and hallux valgus angle on the right foot in the sitting and standing positions using a 3D foot scanner. Then, we calculated the navicular drop and changes in the calcaneus inclination from the sitting to the standing position. The muscle thickness of the flexor hallucis brevis (FHB), flexor digitorum brevis (FDB), and abductor hallucis (AbH) was measured on the right foot using Bmode ultrasonography.

RESULTS

Multiple regression analysis demonstrated that FHB thickness was significantly associated with navicular height in the standing positions (β = 8.568, P = 0.016) as well as navicular drop (β = -9.495, P = 0.037) after adjusting for age, sex, height, weight, and hallux valgus angle. There was no association with FDB or AbH. The thickness of any intrinsic muscle was not associated with the calcaneus inclination or changes in the calcaneus inclination.

SIGNIFICANCE

Our data suggest that FHB plays an important role in preventing navicular drop and that intrinsic muscles likely do not contribute to the rearfoot angle in older adults.

Is subtalar extra articular screw arthroereisis (SESA) reducing pain and restoring medial longitudinal arch in children with flexible flat foot?

Subtalar arthroereisis has been accounted for as a minimally invasive, successful and generally safe technique in the treatment of flatfoot in children. The primary aim of our study was to evaluate the subtalar extra-articular screw arthroereisis (SESA) in children with flexible flatfoot clinically and radiologically. This prospective case series study included 84 feet of 42 patients who underwent Subtalar Extra-articular Screw Arthroereisis (SESA) due to symptomatic flexible flatfoot. This study included 26 males (62 ℅) and 16 females (38℅). The mean age at surgery was (9.92 years); range from (7-15 years).The average follow up period was 29.1 months (ranged from 2 to 48 months). The values of the pre- and post-SESA weight bearing X-ray angles were 149 ± 6 and 127° ± 8° respectively for the Costa-Bartani angle, 43° ± 8° and 25° ± 6° respectively for the lateral T-1stMT angle and 26° ± 7° and 8° ± 3° respectively for calcaneal pitch angle 6° ± 4° and 15° ± 5°. The average AOFAS preoperative score was 68.7 ± 5.7 (Range, 58 to 78) whereas post operative AOFAS score was 97.4 ± 2.3 (range, 94 to 100). All data were analyzed statistically with graph instat. With final conclusion that SESA is an optimal technique for the correction of flexible flatfoot (FFF) as it is simple and can be performed rapidly and is effective procedure in reducing pain and restoring medial longitudinal arch in children with flexible flat foot. Level of clinical evidence (LOCE): Level 4.

Correlation between radiographic morphometry and body surface somatometry for foot arches

[Purpose] Foot arches are evaluated using radiographic morphometry and body surface somatometry. While several studies have examined the correlations between these methods and the medial longitudinal arch, very few studies have investigated the same for transverse arches. In this study, we analyzed the correlation between radiographic morphometry and body surface somatometry at medial longitudinal and transverse arches. [Participants and Methods] Fifty healthy adults were included in the study. Six medial longitudinal and three transverse arch evaluation methods were evaluated for the correlation, including the foot posture index. [Results] A correlation was found between the evaluation methods for the medial longitudinal arch, except the lateral talocalcaneal angle; however, no correlation was found between the navicular-metatarsal angle and transverse arch-length ratio in transverse arch evaluation. Additionally, there was no correlation between the evaluation methods for the medial longitudinal and transverse arches. The foot posture index was particularly correlated with radiographic medial longitudinal arch evaluation methods. [Conclusion] During evaluation with radiographic morphometry, it is difficult to set bone markers and differences in tarsal bone arrangement affect the relationship between them; in body surface somatometry, there were differences in measurement at sites with excessive soft tissue. Elucidating the cause for the lack of correlation between the medial longitudinal and transverse arches requires further investigation.

Correlation between three-dimensional medial longitudinal arch joint complex mobility and medial arch angle in stage II posterior tibial tendon dysfunction

BACKGROUND

The purpose of this study was to evaluate correlation between three-dimensional medial longitudinal arch joint complex mobility and medial arch angle in stage II posterior tibial tendon dysfunction flatfoot under loading.

METHODS

CT scans of 15 healthy feet and 15 feet with stage II posterior tibial tendon dysfunction flatfoot were taken both in non- and simulated weight-bearing condition. The CT images of the hindfoot and medial longitudinal arch bones were reconstructed into three-dimensional models with Mimics and Geomagic reverse engineering software. The three-dimensional complex mobility of each joint in the medial longitudinal arch and their correlation with the medial arch angle change were calculated.

RESULTS

From non- to simulated weight-bearing condition, the medial arch angle change and the medial longitudinal arch joints mobility were significant larger in stage II posterior tibial tendon dysfunction flatfoot (p<0.05). The eversion of the talocalcaneal joint, the proximal translation of the calcaneus relative to the talus, the dorsiflexion of the talonavicular joint, the dorsiflexion and abduction of the medial cuneonavicular joint, and the lateral translation of the medial cuneiform relative to the navicular, and the dorsiflexion of the first tarsometatarsal joint were all significantly correlated to the medial arch angle change in stage II posterior tibial tendon dysfunction flatfoot (all r>0.5, p<0.05).

CONCLUSIONS

There is increased mobility in the medial longitudinal arch joints in stage II posterior tibial tendon dysfunction flatfoot and the medial arch angle change under loading causes displacement not only at hindfoot joints but also involve midfoot and forefoot joint.

Validation of a novel Kinect-based device for 3D scanning of the foot plantar surface in weight-bearing

Background

Advancements in additive manufacturing, along with new 3D scanning tools, are increasingly fulfilling the technological need for custom devices in personalized medicine. In podiatry and in the footwear industry, custom orthotic and footwear solutions are often required to address foot pathologies or morphological alterations which cannot be managed with standard devices. While laser scanners are the current gold-standard for 3D digitization of the foot shape, their costs limit their applications and diffusion, therefore traditional operator-dependent casting methods are still in use. The aim of this study was to design and validate a novel 3D foot scanner based on the Microsoft Kinect sensor, allowing a 3D scan of the plantar shape of the foot to be acquired in weight-bearing.

Methods

The accuracy and repeatability of the prototypal foot scanner were investigated in a population of 14 asymptomatic healthy subjects, with no history of foot or lower limb injuries. The accuracy was estimated by comparing the Kinect foot scans with those obtained with a high-resolution laser scanner used as reference. The repeatability was assessed by comparing scans of the same foot acquired in different sessions.

Results

The inter-subject average Root Mean Square Error (RMSE) of the Kinect scans was lower than 3 mm for the whole plantar surface, and lower than 1.6 mm for the arch region alone, both in left and right feet. The repeatability, quantified as the average RMSE of pairwise comparisons between sessions, was 1.2 ± 0.4 mm.

Conclusions

The present Kinect-based 3D foot scanner showed optimal intra-operator repeatability and its accuracy appears adequate to obtain 3D scans of the foot plantar surface suitable for different clinical applications. This device could represent a valid low-cost alternative to expensive laser-based scanners and could be used for automatic foot measurements, supporting the design of custom insoles and footwear.

The relationship between static and dynamic foot posture and running biomechanics: A systematic review and meta-analysis

BACKGROUND

Medial longitudinal arch characteristics are thought to be a contributing factor to lower limb running injuries. Running biomechanics associated with different foot types have been proposed as one of the potential underlying mechanisms. However, no systematic review has investigated this relationship.

RESEARCH QUESTION

The aim of this study was to conduct a systematic literature search and synthesize the evidence about the relationship between foot posture and running biomechanics.

METHODS

For this systematic review and meta-analysis different electronic databases (Pubmed, Web of Science, Cochrane, SportDiscus) were searched to identify studies investigating the relationship between medial longitudinal arch characteristics and running biomechanics. After identification of relevant articles, two independent researchers determined the risk of bias of included studies. For homogenous outcomes, data pooling and meta-analysis (random effects model) was performed, and levels of evidence determined.

RESULTS

Of the 4088 studies initially identified, a total of 25 studies were included in the qualitative review and seven in the quantitative analysis. Most studies had moderate and three studies a low risk of bias. Moderate evidence was found for a relationship between foot posture and subtalar joint kinematics (small pooled effects: -0.59; 95%CI -1.14 to - 0.003) and leg stiffness (small pooled effect: 0.59; 95%CI 0.18 to 0.99). Limited or very limited evidence was found for a relationship with forefoot kinematics, tibial/leg rotation, tibial acceleration/shock, plantar pressure distribution, plantar fascia tension and ankle kinetics as well as an interaction of foot type and footwear regarding tibial rotation.

SIGNIFICANCE

While there is evidence for an association between foot posture and subtalar joint kinematics and leg stiffness, no clear relationship was found for other biomechanical outcomes. Since a comprehensive meta-analysis was limited by the heterogeneity of included studies future research would benefit from consensus in foot assessment and more homogenous study designs.

Reliability of medial-longitudinal-arch measures for skin-markers based kinematic analysis

The medial-longitudinal arch (MLA) is perhaps the most important feature characterizing foot morphology. While current skin-markers based models of the MLA angle used in stereophotogrammetry allow to estimate foot arch shape and deformation, these do not always appear consistent with foot anatomy and with standard clinical definitions. The aim of this study was to propose novel skin-markers based measures of MLA angle and investigate their reliability during common motor tasks. Markers on the calcaneus, navicular tuberosity, first metatarsal head and base, and on the two malleoli were exploited to test eight definitions of MLA angle consistent with foot anatomy, both as angles between two 3-dimensional vectors and as corresponding projections on the sagittal plane of the foot. The inter-trial, inter-session and inter-examiner reliability of each definition was assessed in multiple walking and running trials of two volunteers, tested by four examiners in three sessions. Inter-trial variability in walking was in the range 0.7-1.2 deg, the inter-session 2.8-7.5 deg, and the inter-examiner in the range 3.7-9.3 deg across all MLA definitions. The Rizzoli Foot Model definition showed the lowest inter-session and inter-examiner variability. MLA measures presented similar variability in walking and running. This study provides preliminary information on the reliability of MLA measurements based on skin-markers. According to the present study, angles between 3-dimensional vectors and minimal marker sets should be preferred over sagittal-plane projections. Further studies should be sought to investigate which definition is more accurate with respect to the real MLA deformation in different loading conditions.

Flatfeet: Biomechanical implications, assessment and management

Several complications due to flatfeet have been reported in previous literature such as poor postural stability, injuries, pathologies, and discomfort. Early detection and appropriate management are mandatory to minimize these effects. There are different feet assessments established in the field with distinct advantages and disadvantages. Additionally, selection of management methods from various options should be done vigilantly as the application differs according to the individual. Therefore, the objective of this article is to review previous literature on structural anatomy, pathomechanics, assessment, and proper management of flatfeet to provide a condensed summary for healthcare professionals, occupational therapists, kinesiologists, biomechanists, coaches, and ergonomists.

The effect of additional activation of the plantar intrinsic foot muscles on foot kinematics in flat-footed subjects

BACKGROUND

Strengthening exercises of the plantar intrinsic foot muscles (PIFMs) are often prescribed to flat-footed subjects because of the capacity of the PIFMs to support the medial longitudinal arch (MLA). However, it is unclear whether the capacity of the PIFMs to support the MLA is enough to change the foot kinematics in flat-footed subjects. To confirm this, the current study examined changes in foot kinematics in flat-footed subjects during standing and gait accompanied by changes in the activity of the PIFMs.

METHODS

Eighteen flat-footed subjects were randomly assigned to an electrical stimulation group (ESG) or a control group (CG). In the ESG, electrical stimulation to the PIFMs was applied during standing and gait to simulate reinforcement of the PIFMs. Then, foot kinematics were measured using 3D motion analysis, and the amount of change from baseline (when no electrical stimulation was applied) was compared between the groups.

RESULTS

In the gait analysis, the time at which the MLA height reached its minimum value was significantly later in the ESG, with no reduction in the MLA height at that time. Moreover, forefoot inversion angle and tibial external rotation angle were significantly increased in the ESG at that time. In the standing analysis, there were no significant differences between the groups.

CONCLUSION

The results revealed that in flat-footed subjects, the PIFMs have the capacity to support the MLA enough to change foot kinematics during gait. Strengthening these muscles may be effective in preventing or treating lower extremity overuse injuries related to flat-foot alignment.

Effect of plano-valgus foot posture on midfoot kinematics during barefoot walking in an adolescent population

Background

Plano-valgus is a common alteration of the paediatric foot, characterized by valgus hindfoot, foot pronation and drop of the medial longitudinal arch. Despite their importance in the diagnosis and classification of plano-valgus foot condition, little information is available on functional alterations of the major joints spanning the medial longitudinal arch – i.e. midtarsal and tarso-metatarsal. Aim of the study was to provide objective description of the alterations in plano-valgus midfoot joints with respect to those in an age-matched normally-developed feet population.

Methods

Twenty adolescents (13.3 ± 0.8 years) with bilateral plano-valgus feet underwent clinical examination and were gait-analysed via a validated 4-segment foot model. This allowed to measure static foot posture, kinematics of the main foot joints, and medial longitudinal arch deformation during walking at comfortable speed. Range of motion and temporal profiles of joint rotations were compared to those from a control population of age-matched adolescents with normally-developed feet.

Results

The plano-valgus midtarsal joint was more dorsiflexed, everted and abducted than that in the control group, and showed reduced sagittal-plane RoM (plano-valgus = 15.9 degrees; control = 22.2 degrees; P <  0.01). The tarso-metarsal joint was more plantarflexed and adducted, and showed larger frontal-plane RoM. The MLA showed larger RoM and was lower throughout the stance phase of the gait cycle.

Conclusion

Significant postural and kinematic alterations are present at the midtarsal and tarso-metarsal joints of adolescents with plano-valgus feet. Objective identification and quantification of plano-valgus foot alterations, via non-invasive gait-analysis, is relevant to improving the diagnosis of this condition and to evaluating the effect of conservative treatments and of surgical corrections by different techniques.

Gender difference in factors affecting the medial longitudinal arch height of the foot in healthy young adults

[Purpose] Medial longitudinal arch (MLA) height is associated with various injuries and diseases and gender differences, if any. This study aimed to examine factors affecting the MLA height associated with gender differences in healthy subjects with no orthopedic disorders. [Subjects and Methods] This study included 36 healthy adults (19 males, 17 females; mean age, 21.8 ± 3.6 years; body mass index, 21.1 ± 2.0 kg/m²). Their height, body weight, foot length, muscle strength of the tibialis posterior muscle (TPM), toe-gripping strength, hallux valgus angle, inversion microdactylia angle, angle of leg-heel alignment, femoro-tibial angle, and navicular height were measured. Correlation between the ratio of arch height and other measurement parameters was examined. [Results] In females, the ratio of arch height was significantly positively correlated with muscle strength of the TPM and toe-gripping strength and negatively correlated with the hallux valgus angle and the leg-heel alignment, whereas in males, only a positive correlation between the ratio of arch height and muscle strength of the TPM was observed. [Conclusion] These results reveal that etiological mechanisms determining MLA height are different between males and females. Overall, the present results indicate that further studies identifying causes of MLA height variation must include gender-based analysis.

Arch index and running biomechanics in children aged 10-14 years

BACKGROUND

While altered foot arch characteristics (high or low) are frequently assumed to influence lower limb biomechanics and are suspected to be a contributing factor for injuries, the association between arch characteristics and lower limb running biomechanics in children is unclear.

RESEARCH QUESTION

Therefore, the aim of this study was to investigate the relationship between a dynamically measured arch index and running biomechanics in healthy children.

METHODS

One hundred and one children aged 10-14 years were included in this study and underwent a biomechanical investigation. Plantar distribution (Novel, Emed) was used to determine the dynamic arch index and 3D motion capture (Vicon) to measure running biomechanics. Linear mixed models were established to determine the association between dynamic arch index and foot strike patterns, running kinematics, kinetics and temporal-spatial outcomes.

RESULTS

No association was found between dynamic arch index and rate of rearfoot strikes (p = 0.072). Of all secondary outcomes, only the foot progression angle was associated with the dynamic arch index (p = 0.032) with greater external rotation in lower arched children.

SIGNIFICANCE

Overall, we found only few associations between arch characteristics and running biomechanics in children. However, altered foot arch characteristics are of clinical interest. Future studies should focus on detailed foot biomechanics and include clinically diagnosed high and low arched children.

Effect of total-contact orthosis on medial longitudinal arch and lower extremities in flexible flatfoot subjects during walking

BACKGROUND

Total-contact orthosis (TCO) is one kind of foot orthosis (FO) that is used to adjust biomechanics in flexible flatfoot.

OBJECTIVE

To determine the effects of a TCO on the MLA moment, MLA deformation angle and lower limb biomechanics.

STUDY DESIGN

Cross-sectional study.

METHODS

Seven-flatfoot and thirteen-normal foot subjects were recruited by footprint and radiographs. The biomechanics of subjects with normal foot (NF), flatfoot with shoe only (FWOT) and flatfoot with TCO (FWT) were collected in a 3D motion analysis laboratory and force plates. The MLA and lower limb biomechanics in each condition during specific sub-phases of stance were analyzed.

RESULTS

The NF had larger MLA eversion moment after shod walking ( p = 0.001). The FWT condition compared with the FWOT condition had a significantly larger peak MLA upward moment ( p = 0.035) during pre-swing, larger peak knee external rotation angle ( p = 0.040) during mid stance, smaller peak knee extension moment during terminal stance ( p = 0.035) and a larger ground reaction force in the anterior-posterior direction during early stance ( p < 0.05).

CONCLUSION

Our study found positive effects from the customized TCOs which included an increased TCO angle that led to a decreased peak MLA moment in the frontal plane in flexible flatfoot subjects during walking. Clinical relevance Lower limb biomechanics is different from normal in subjects with flexible flatfoot. The design of a TCO affects MLA, ankle and knee biomechanics and may be used to clinically correct biomechanical changes in flexible flatfoot.

Prevalence of Flexible Flat Foot in Adults: A Cross-sectional Study

INTRODUCTION

Flat foot (pes planus) is a commonly observed disorder in clinical practice. The height of Medial Longitudinal Arch (MLA) determines the degree of pes planus. Majority of the previous studies on prevalence of flexible flat foot were done among children.

AIM

The present study was undertaken to determine the prevalence of flexible flat foot among 18-21-year-old Indian adults using Navicular Drop Test (NDT) which is regarded as reliable and valid method to characterise MLA.

MATERIALS AND METHODS

The present study was a cross-sectional study in which Brody's Navicular Drop Test was performed in five hundred healthy subjects (250 males and 250 females) aged 18-21-year-old. Navicular Drop (ND) of ≥ 10 mm was regarded as flexible flat foot. Statistical analysis was done using SPSS version 23.0.

RESULTS

The prevalence of flexible flat foot was 13.6% (for males-12.8%; for females-14.4%). The median with Inter Quartile Range (IQR) for ND among males was 6 mm (4-8) and 6 mm (4-9) for right and left foot respectively. The median with IQR for ND among females was 6mm (4-10) and 7mm (3-8) for right & left respectively. The correlation of Right Side Navicular Drop (RND) with height and weight was significant, but insignificant correlation was found between RND and BMI. The correlation of Left Side Navicular Drop (LND) with height, weight and BMI of individuals was statistically not significant. The difference between the ND of males and female group was statistically not significant.

CONCLUSION

The present study quantified the prevalence of flexible flat foot and gender wise normative values of ND among 18-21-year-old Indian adults. The information obtained by this study will be useful in the field of orthopaedics.

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

OBJECTIVE

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

METHOD

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

RESULTS

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

CONCLUSION

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

The influence of the Peroneus Longus muscle on the foot under axial loading: A CT evaluated dynamic cadaveric model study

BACKGROUND

Subtle hypermobility of the first tarsometatarsal joint can occur concomitantly with other pathologies and may be difficult to diagnose. Peroneus Longus muscle might influence stability of this joint. Collapse of the medial longitudinal arch is common in flatfoot deformity and the muscle might also play a role in correcting Meary's angle.

METHODS

A radiolucent frame was used to simulate weightbearing during CT examination. Eight pairs fresh-frozen lower legs were imaged in neutral position under non-weightbearing (75N), weightbearing (700N) and with 15kg weights hung from Peroneus Longus tendon. Measurements included first metatarsal rotation, intermetatarsal angle, first tarsometatarsal joint subluxation and Meary's angle.

FINDINGS

Weightbearing significantly increased Meary's angle and significantly decreased first tarsometatarsal joint subluxation (both P<0.01). Pulling Peroneus Longus tendon significantly increased first metatarsal rotation (P<0.01), significantly decreased the intermetatarsal angle (P<0.01) and increased non-significantly Meary's angle (P=0.52).

INTERPRETATION

A considerable effect weightbearing has on the medial longitudinal arch and first tarsometatarsal joint was observed. Pulling Peroneus Longus tendon improved first metatarsal subluxation but increased its rotation. The study calls into question the importance of this tendon in maintaining the medial longitudinal arch and raises concerns about rotational deformity of the first metatarsal following hallux valgus correction without first tarsometatarsal arthrodesis.

CLINICAL RELEVANCE

Study outcomes will provide more insight in foot pathology.

WHAT IS KNOWN ABOUT THE SUBJECT

Weightbearing affects anatomy of the foot. No reliable information is available concerning the influence of the Peroneus muscle.

WHAT THIS STUDY ADDS TO EXISTING KNOWLEDGE

This study investigates the influence of weightbearing and the impact the Peroneus muscle on the anatomy of the foot.

Elastic energy within the human plantar aponeurosis contributes to arch shortening during the push-off phase of running

During locomotion, the lower limb tendons undergo stretch and recoil, functioning like springs that recycle energy with each step. Cadaveric testing has demonstrated that the arch of the foot operates in this capacity during simple loading, yet it remains unclear whether this function exists during locomotion. In this study, one of the arch׳s passive elastic tissues (the plantar aponeurosis; PA) was investigated to glean insights about it and the entire arch of the foot during running. Subject specific computer models of the foot were driven using the kinematics of eight subjects running at 3.1m/s using two initial contact patterns (rearfoot and non-rearfoot). These models were used to estimate PA strain, force, and elastic energy storage during the stance phase. To examine the release of stored energy, the foot joint moments, powers, and work created by the PA were computed. Mean elastic energy stored in the PA was 3.1±1.6J, which was comparable to in situ testing values. Changes to the initial contact pattern did not change elastic energy storage or late stance PA function, but did alter PA pre-tensioning and function during early stance. In both initial contact patterns conditions, the PA power was positive during late stance, which reveals that the release of the stored elastic energy assists with shortening of the arch during push-off. As the PA is just one of the arch׳s passive elastic tissues, the entire arch may store additional energy and impact the metabolic cost of running.

Selected static foot assessments do not predict medial longitudinal arch motion during running

Background

Static assessments of the foot are commonly advocated within the running community to classify the foot with a view to recommending the appropriate type of running shoe. The aim of this work was to determine whether selected static foot assessment could predict medial longitudinal arch (MLA) motion during running.

Methods

Fifteen physically active males (27 ± 5 years, 1.77 ± 0.04 m, 80 ± 10 kg) participated in the study. Foot Posture Index (FPI-6), MLA angle and rearfoot angle were measured in a relaxed standing position. MLA motion was calculated using the position of retro-reflective markers tracked by a VICON motion analysis system, while participants ran barefoot on a treadmill at a self-selected pace (2.8 ± 0.5 m.s⁻¹). Bivariate linear regression was used to determine whether the static measures predicted MLA deformation and MLA angles at initial contact, midsupport and toe off.

Results

All three foot classification measures were significant predictors of MLA angle at initial contact, midsupport and toe off (p < .05) explaining 41–90 % of the variance. None of the static foot classification measures were significant predictors of MLA deformation during the stance phase of running.

Conclusion

Selected static foot measures did not predict dynamic MLA deformation during running. Given that MLA deformation has theoretically been linked to running injuries, the clinical relevance of predicting MLA angle at discrete time points during the stance phase of running is questioned. These findings also question the validity of the selected static foot classification measures when looking to characterise the foot during running. This indicates that alternative means of assessing the foot to inform footwear selection are required.

Electronic supplementary material

The online version of this article (doi:10.1186/s13047-015-0113-6) contains supplementary material, which is available to authorized users.

Relationship between navicular drop and measuring position of maximal plantar flexion torque of the first and second-fifth metatarsophalangeal joints

[Purpose] The purpose of this study was to determine the relationship between navicular drop and plantar flexion torque of the first and second-fifth metatarsophalangeal joints. [Subjects] Ten healthy young men participated in this study. [Methods] The Pearson product-moment correlation coefficient was calculated to determine the relationship between navicular drop and plantar flexion torque of the first and second-fifth metatarsophalangeal joints. [Results] Significant negative correlations were observed between navicular drop and plantar flexion torques in the lengthened position of the intrinsic toe plantar flexion muscles, but no correlations were found between navicular drop and plantar flexion torques in the neutral position of the ankle and metatarsophalangeal joints. Moreover, the intrinsic toe plantar flexion muscles were found to contribute to the formation of the medial longitudinal arch. [Conclusion] Navicular drop correlates with metatarsophalangeal joint muscle strength in plantar flexion where the intrinsic toe muscles are capable of exerting force.

Effect of therapeutic insoles on the medial longitudinal arch in patients with flatfoot deformity: a three-dimensional loading computed tomography study

BACKGROUND

Insoles are frequently used in orthotic therapy as the standard conservative treatment for symptomatic flatfoot deformity to rebuild the arch and stabilize the foot. However, the effectiveness of therapeutic insoles remains unclear. In this study, we assessed the effectiveness of therapeutic insoles for flatfoot deformity using subject-based three-dimensional (3D) computed tomography (CT) models by evaluating the load responses of the bones in the medial longitudinal arch in vivo in 3D.

METHODS

We studied eight individuals (16 feet) with mild flatfoot deformity. CT scans were performed on both feet under non-loaded and full-body-loaded conditions, first with accessory insoles and then with therapeutic insoles under the same conditions. Three-dimensional CT models were constructed for the tibia and the tarsal and metatarsal bones of the medial longitudinal arch (i.e., first metatarsal bone, cuneiforms, navicular, talus, and calcaneus). The rotational angles between the tarsal bones were calculated under loading with accessory insoles or therapeutic insoles and compared.

FINDINGS

Compared with the accessory insoles, the therapeutic insoles significantly suppressed the eversion of the talocalcaneal joint.

INTERPRETATION

This is the first study to precisely verify the usefulness of therapeutic insoles (arch support and inner wedges) in vivo.

Multi-segment foot kinematics and ground reaction forces during gait of individuals with plantar fasciitis

BACKGROUND

Clinically, plantar fasciitis (PF) is believed to be a result and/or prolonged by overpronation and excessive loading, but there is little biomechanical data to support this assertion. The purpose of this study was to determine the differences between healthy individuals and those with PF in (1) rearfoot motion, (2) medial forefoot motion, (3) first metatarsal phalangeal joint (FMPJ) motion, and (4) ground reaction forces (GRF).

METHODS

We recruited healthy (n=22) and chronic PF individuals (n=22, symptomatic over three months) of similar age, height, weight, and foot shape (p>0.05). Retro-reflective skin markers were fixed according to a multi-segment foot and shank model. Ground reaction forces and three dimensional kinematics of the shank, rearfoot, medial forefoot, and hallux segment were captured as individuals walked at 1.35 ms(-1).

RESULTS

Despite similarities in foot anthropometrics, when compared to healthy individuals, individuals with PF exhibited significantly (p<0.05) (1) greater total rearfoot eversion, (2) greater forefoot plantar flexion at initial contact, (3) greater total sagittal plane forefoot motion, (4) greater maximum FMPJ dorsiflexion, and (5) decreased vertical GRF during propulsion.

CONCLUSION

These data suggest that compared to healthy individuals, individuals with PF exhibit significant differences in foot kinematics and kinetics. Consistent with the theoretical injury mechanisms of PF, we found these individuals to have greater total rearfoot eversion and peak FMPJ dorsiflexion, which may put undue loads on the plantar fascia. Meanwhile, increased medial forefoot plantar flexion at initial contact and decreased propulsive GRF are suggestive of compensatory responses, perhaps to manage pain.

Foot lengthening and shortening during gait: a parameter to investigate foot function?

INTRODUCTION

Based on the windlass mechanism theory of Hicks, the medial longitudinal arch (MLA) flattens during weight bearing. Simultaneously, foot lengthening is expected. However, changes in foot length during gait and the influence of walking speed has not been investigated yet.

METHODS

The foot length and MLA angle of 34 healthy subjects (18 males, 16 females) at 3 velocities (preferred, low (preferred -0.4 m/s) and fast (preferred +0.4 m/s) speed were investigated with a 3D motion analysis system (VICON(®)). The MLA angle was calculated as the angle between the second metatarsal head, the navicular tuberculum and the heel in the local sagittal plane. Foot length was calculated as the distance between the marker at the heel and the 2nd metatarsal head. A General Linear Model for repeated measures was used to indicate significant differences in MLA angle and foot length between different walking speeds.

RESULTS

The foot lengthened during the weight acceptance phase of gait and shortened during propulsion. With increased walking speed, the foot elongated less after heel strike and shortened more during push off. The MLA angle and foot length curve were similar, except between 50% and 80% of the stance phase in which the MLA increases whereas the foot length showed a slight decrease.

CONCLUSION

Foot length seems to represent the Hicks mechanism in the foot and the ability of the foot to bear weight. At higher speeds, the foot becomes relatively stiffer, presumably to act as a lever arm to provide extra propulsion.

Comparison of the calcaneal pitch angle and modified projection area per length squared method for medial longitudinal arch evaluation of the foot

OBJECTIVE

To compare the calcaneal pitch angle (CPA) values measured on direct lateral radiographs of feet, and the modified projection area per length squared (PAL), which was calculated as a new method for the evaluation of the medial longitudinal arch (MLA) of the foot.

MATERIAL AND METHODS

Direct lateral radiographs of patients who had weightbearing feet radiographies for any reason except trauma were retrospectively obtained from the archives. Direct lateral radiographs of the feet were printed and a transparent sheet was placed on it. A straight line was drawn between the most plantar process of the calcaneus and the head of the first metatarsal bone for the calculation of the PAL of the MLA. Two semilunar arcs were drawn upon this straight line. PAL1 and PAL2 were estimated using a point-counting technique. The CPA, lateral talo-calcaneal angles (LTCA), and talo-first metatarsal angles (TFMA) were measured. The correlations between PAL1, PAL2 of right and left feet and CPA, LTCA, and TFMA were explored.

RESULTS

Fifty patients (27 females, 23 males) with a mean age of 40.12 (4-78) years were evaluated. Significant correlations were detected between PAL1, PAL2 and CPA, and TFMA for both right and left feet (p<0.05).

CONCLUSION

A significant correlation was detected between the modified PAL method as a new technique and the standard CPA method for MLA evaluation. The PAL method is suggested as a simple and practical method for MLA evaluation.