Planus Foot Research Articles

The effect of a 12-week custom foot orthotic intervention on muscle size and muscle activity of the intrinsic foot muscle of young adults during gait termination

BackgroundThe tissue stress theory is commonly used to prescribe foot orthoses, however the mechanisms of foot orthoses are not understood well. The effect foot orthotics have on the plantar intrinsic muscles remains unclear. The study was designed to assess changes in muscle size and activity of the intrinsic muscles of individuals with pes planus after wearing custom-made foot orthotics for 12-weeks. MethodsEighteen young adults with pes planus were allocated by stratified sampling into the orthotic group (n = 9) or control group (n = 9). Ultrasonography measured the cross-sectional area of the flexor digitorum brevis, abductor digiti minimi, and abductor hallucis at baseline, 6 and 12-weeks. Subsequently, participants completed an unexpected gait termination protocol (12 of 50 trials unexpected) and average electromyography magnitude was recorded. FindingsAfter 12-weeks the orthotic group cross-sectional area significantly decreased by 9.6% (P < .001) for the flexor digitorum brevis, 17.1% for abductor digiti minimi (P < .001) and 17.4% for abductor hallucis (P < .001). There were no significant differences of muscle activity magnitude for the intrinsic muscles. InterpretationThe short-term use of custom-made foot orthoses created a decrease in muscle size of the flexor digitorium brevis, abductor digiti minimi and abductor hallucis plantar intrinsic muscles but had no effect on muscle activity. Clinically, these results help to understand the adaptations that are created when foot orthoses are supporting a pes planus foot structure when reducing plantar pressures. These findings may help enhance the prescription of foot orthoses by adding a strength program to prevent disuse atrophy of these muscles.

Musculoskeletal abnormalities in a large international cohort of boys with 49,XXXXY.

49,XXXXY is the rarest X and Y chromosomal variation, with an incidence of 1 in 80,000-100,000 live male births and has been associated with numerous musculoskeletal abnormalities. Data was collected from an international cohort of boys with 49,XXXXY over 10 years. Children were evaluated by a multidisciplinary team consisting of a pediatric orthopedist, a neurogeneticist, a neurodevelopmentalist, and two physical therapists. Increased rates of torticollis (32.4%), hamstring tightness (42%), radioulnar synostosis (67.6%), pes planus (65.2%), and other foot abnormalities (86.9%) were observed. Several anomalies increased with age, specifically hamstring tightness, kyphosis, and scoliosis. The elucidation of the orthopedic profile of this population is necessary in order to provide healthcare providers with current medical information. This research further supports the necessity for the comprehensive multidisciplinary treatment of boys with 49,XXXXY.

Radiographic measurements of the talus and calcaneus in the adult pes planus foot type.

A distinctive feature of the modern human foot is the presence of a medial longitudinal arch when weight-bearing. Although the talus and calcaneus play a major role in the structure and function of the human foot, the association between the morphology of these bones and longitudinal arch height has not been fully investigated. A better understanding of this relationship may assist in the interpretation of pedal remains of fossil hominins, where features of the foot and ankle morphology have been described as providing evidence for the presence of a longitudinal arch. For this study, weight-bearing radiographs of 103 patients from an urban US Level 1 trauma center, taken as part of a clinical examination for medical evaluation, were selected. These radiographs were classified as to foot type by arch height as defined using the calcaneal inclination angle. From this group, 68 radiographs were suitable for linear and angular measurements of the talus and 74 of the calcaneus. The relationships between these measurements and arch height were explored using least squared linear regression analysis. The results demonstrate that angular measurements of the calcaneus (particularly those that reflect the relationship of the talar articular facets to each other and the tilt of the calcaneocuboid joint to the longitudinal axis of the calcaneus) are predictive of arch height (r2 = .29-.44 p ≤ .001). All angular measurements of the talus and all examined linear measurements of both the talus and calcaneus were not predictive of arch height. These results suggest that certain angular measurements of the calcaneus are associated with arch height in the modern human foot. While this information is useful in the interpretation of hominin pedal remains, the relationship of the morphology of these bones, as well as other bones of the foot, to arch height is complex, requiring further investigation.

Tarsal Morphology Differs in Plano Valgus Feet

Category:HindfootIntroduction/Purpose:While there are established associated conditions, the intrinsic cause of symptomatic adult flatfoot is not known. There are published data suggesting that the relationship of the hindfoot bones in acquired flatfoot are subluxated. And there is some support in 2 D for the concept that the bones are shaped differently in flatfoot but the complexity of bone shape and human variation makes comparisons difficult. The purpose of this study was to utilize principal component analysis (PCA) to determine whether morphology of the hind- and midfoot bones differs in neutral and plano-valgus feet.Methods:Forty subjects (23 male and 17 Female, average age 52.6 +/- 8.9) with no history of injury or surgery underwent bilateral foot WB CT scan for another study. The talus, calcaneus, navicular and cuboid were segmented into bone models from these previously acquired CT images. Morphometric Shape analysis software (Geomorph) was used to assess shape variations among foot types using Principal component analysis (PCA). PCA is a statistical modelling technique used to study variation in the shape of structures that are difficult to compare and bring out strong patterns in a dataset objectively. Forty feet had been classified into 4 foot groups prior to this study; neutral, cavus, asymptomatic flatfoot and symptomatic flatfoot. This study included the painful flatfeet and neutral feet. Each bone was compared between the feet that were flat and those that were neutral. Comparisons were made between men and women as well.Results:There were no differences between groups in age or sex. There were 38 principle components identified. The first two PC accounted for 38% of the calcaneal variation and 33% of the talar variation. Subtle differences between men and women were found only at the talus and navicular. The cuboid did not exhibit any differences between foot types. The navicular in symptomatic planus had a more posteriorly positioned tuberosity (tuber wrapped around the medial side of the talus) and were wider than neutral feet. The calcaneus showed planus feet to have calcanei that have decreased height and increased length compared to neutrally aligned feet. The cross -sectional area of the calcaneus was reduced compared to neutral feet. The talar shape was not different in the PC.Conclusion:A flat foot is present in over 20% of the population and most often not symptomatic. The root cause of symptomatic adult plano valgus foot is not known and is likely multi factorial. The study demonstrates that there is intrinsic difference in the shape of the calcaneus and navicular bones in flat foot. it is possible that the catalyst for collapse is bony rather than soft tissue.

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

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

Comparison of plantar pressure variables during walking at different speeds between individuals with planus and normal feet: a pilot study

Comparison of plantar pressure variables during walking at different speeds between individuals with planus and normal feet: a pilot study

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

Footprints have long been used as proxy measures of foot morphology, yet there is little consensus regarding footprints versus measures of foot posture, which address foot anatomy directly. Foot posture in children can be a confusing clinical presentation, with previous studies both supporting and refuting the relationship between childhood obesity and flat feet. The aim of this study was to determine the relationship between footprints and foot posture in children. A total of 316 school children (153 boys, 163 girls) from Spain, aged 6-9 years, were assessed for both footprint (Clarke's angle (CA)), by Tecniwork Pedrograph Plate, and foot posture (foot posture index (FPI)) measures, with participants barefoot, in a relaxed standing position, on a 50-cm elevated platform. A negative correlation was found between FPI and footprints (CA) (rho = -0.505 left, P < 0.001) and by gender (rho = -0.457 for the left foot in girls, P < 0.001; rho = -0.548 for the left foot in boys, P < 0.001). The children with pes cavus according to the CA (73.3%) had normal feet according to FPI, and the children with severe pes planus according to the CA (78.98%) had pronated feet according to the FPI. A χ2 test showed these results to be statistically significant (P > 0.001). An inverse relationship between CA and FPI was identified, that is, the greater the FPI, the smaller the CA, but not all pronated foot are planus feet and not all cavus feet are supinated feet. Footprints may overestimate and misguide paediatric foot posture concerns.

Hubungan Antara Pes Planus Dengan Keseimbangan Dinamis Pada Murid MI Nurul Karim Colomadu

Background: The ability to balance children at the age of development is very important to be reviewed, both in terms of balance sitting, standing, and walking. One of the factors that can cause balance disorders in children is musculoskeletal disorders in the form of deformity of the soles of the feet. The shape of the human foot is divided into three types, namely normal foot, pes planus and cavus foot according to the arcus structure or arches on the soles of the feet. Normally the arch is formed from the first 5 years with a 2-6 year age range. The critical period for arch formation is the age of 6 years (Campbell, 2012). In the early age of school there were 28% - 35% of children experiencing deformity of pes planus, 80% of which were categorized as "moderate". Methods: This research is a type of correlational research with a cross sectional design which aims to determine the relationship between pes planus and the dynamic balance in MI Nurul Karim Colomadu's students. The subjects used were grade 1-5 students with the condition of pes planus at MI Nurul Karim Colomadu, who had determined the inclusion and exclusion criteria. The number of subjects was 40 people with male and female sex from a total population of 92 people. Result: Using the Spearman Correlation Test Based on the table above, it is known that the value of p = 0.869 shows that there is no significant relationship between sex and dynamic balance. The value of r = 0.27 indicates the strength of the weak correlation. While the value of p = 0,000 shows there is a significant relationship between pes planus and dynamic balance. The value of r = -0,599 shows the strength of the medium correlation. Conclusion: One conclusion is 1. The prevalence of pes planus in girls is greater than that of boys, ie 16 boys and 24 girls have Pes Planus.

Method to Evaluate the Sagittal Plane Mobility of the Medial Arch of the Shod Foot with Foot Orthosis

ABSTRACT Introduction Midfoot mobility plays an important role in the orthotic treatment of foot pathomechanical disorders, such as flexible pes planus and abnormal foot pronation. The sagittal plane mobility of the medial arch of only the unshod foot with a foot orthosis has been evaluated for improving therapeutic outcomes. Because foot orthoses are in-shoe devices, it is necessary to evaluate the sagittal plane mobility of the medial arch of the shod foot with a foot orthosis to optimize in-shoe orthotic effectiveness. Materials and Methods This technical note describes a procedure using digital photography to evaluate the sagittal plane mobility of the medial arch of the shod foot with a foot orthosis. The procedure involves digitally photographing two weight-bearing states of the shoe in which the foot orthosis supports the foot: 1) 10% of body weight achieved by sitting, and 2) 50% of body weight achieved by standing. The two digital images of the shoe are then geometrically analyzed to calculate the displacement of the medial height of the dorsal surface of the shoe in response to the change in the two weight-bearing states. Conclusions Clinicians and researchers can use the method described in this note to evaluate the sagittal plane mobility of the medial arch of the shod foot with a foot orthosis. The method is clinically useful for optimizing the in-shoe effectiveness of foot orthoses to treat foot pathomechanical disorders.

Hind- and midfoot bone morphology varies with foot type and sex.

Foot type has been associated with pain, injury, and altered gait mechanics. Morphological variations in foot bones due to foot type variation may impact surgical and therapeutic treatments. The purpose of this study was to utilize principal component analysis (PCA) to determine how morphology of the hind- and midfoot bones differs among foot types and sex. The calcaneus, talus, navicular, and cuboid were segmented using previously obtained computed tomography (CT) scans and converted to surface models. The CTs were sorted into four foot types-cavus, neutrally aligned, asymptomatic planus, and symptomatic planus. Morphometric shape analysis software (Geomorph) was used to perform a PCA to determine which components varied between foot types and between sexes. The calcaneus showed planus feet of both types to have calcanei that have decreased height and increased length compared to neutrally aligned feet. The talus demonstrated increased posterior mass for cavus feet compared to neutrally aligned feet. For the navicular, symptomatic planus had a more posteriorly positioned tuberosity and were wider than asymptomatic planus feet. The cuboid did not exhibit any differences between foot types. Sex differences, found only at the talus and navicular, were subtle. PCA is an objective technique that helped elucidate differences in bone morphology between foot types and sex without needing to determine the features of interest before comparing groups. Understanding these variations can help inform diagnosis of foot pathologies and surgical protocols as well as improve computer models of the foot. Published 2018. This article is a U.S. Government work and is in the public domain in the USA. J Orthop Res 9999:1-16, 2019.

The effect of foot type on the Achilles tendon moment arm and biomechanics

BackgroundThe aim was to calculate the Achilles tendon moment arm in different degrees of plantarflexion for pes planus, pes cavus and normal arched feet. Methods99 patients (99 radiographs; 40 males, 59 females; mean age 49 years, SD 15) with a healthy ankle joint and a preoperative weightbearing lateral radiograph of the foot were included. Three groups (pes planus, pes cavus and normal-arched feet) with equal sample sizes (n=33) were formed. On radiographs, the angle formed between a horizontal line and the line connecting the insertion of the Achilles tendon with the center of rotation of the ankle, was measured. The interrater reliabilities (ICC) of the angle alpha were compared on radiographs and on MRIs. Using the angle alpha, the Achilles tendon moment arm was calculated in different plantarflexion positions. ResultsThe ICC of alpha was higher on radiographs (0.84, [0.73–0.91]) than on MRIs (0.61, [0.27–0.81]). The average alpha was statistically significantly different (normal arched foot 31 degrees (°), pes planus 24°, pes cavus 36°, p=0.021), resulting in a significant shorter Achilles tendon moment arm for pes cavus than for pes planus (p<0.0001) and normal arched feet (p=0.006) in neutral position. ConclusionThe data suggests that it is feasible to use radiographs to measure the Achilles tendon moment arm. The maximum Achilles tendon moment arm is reached at different angles of ankle flexion for pes cavus, pes planus and normal-arched feet. This has to be taken into consideration when planning surgeries.

The Immediate Effect of Foot Orthoses on Subtalar Joint Mechanics and Energetics.

Foot orthoses maybe used in the management of musculoskeletal disorders related to abnormal subtalar joint (STJ) pronation. However, the precise mechanical benefits of foot orthoses for preventing injuries associated with the STJ are not well understood. The aim of this study was to investigate the immediate effect of foot orthoses on the energy absorption requirements of the STJ and subsequently tibialis posterior (TP) muscle function. Eighteen asymptomatic subjects with a pes planus foot posture were prescribed custom-made foot orthoses made from a plaster cast impression. Participants walked at preferred and fast velocities barefoot, with athletic footwear and with athletic footwear plus orthoses, as three-dimensional motion capture, force data, and intramuscular electromyography of the TP muscle were simultaneously collected. Statistical parametric mapping was used to identify time periods across the stride cycle during which footwear with foot orthoses significantly differed to barefoot and footwear only. During early stance, footwear alone and footwear with orthoses significantly reduced TP muscle activation (1%-12%), supination moments (3%-21%), and energy absorption (5%-12%) at the STJ, but had no effect on STJ pronation displacement. The changes in TP muscle activation and STJ energy absorption were primarily attributed to footwear because the addition of foot orthoses provided little additional effect. We speculate that these results are most likely a result of the compliant material properties of footwear. These results suggest that athletic footwear may be sufficient to absorb energy in the frontal plane and potentially reducing any benefit associated with the addition of foot orthoses.

Custom 3D-printed Total Talar Prostheses Restore Normal Joint Anatomy Throughout the Hindfoot

Category: Hindfoot Introduction/Purpose: Third generation total talar prostheses (TTP) are viable options for talar avascular necrosis (AVN) in the absence of neighboring joint pathology. The use of modern three-dimensional (3D) printing allows for the production of custom implants that exactly mimic the patient’s anatomy. The aim of this study is to determine the accuracy of 3D printing in reproducing a synthetic talus, and in doing so, restoring more normal anatomic relationships. We hypothesize that this mode of replication will restore and maintain normal radiographic alignment of the ankle, subtalar, and forefoot joints in the setting of talar AVN. Methods: A retrospective analysis was performed on all patients undergoing TTP implantation for the treatment of talar AVN between 2016 and 2017. Pertinent demographic and operative factors were recorded. Radiographic measurements were taken pre- and post-operatively to determine native talar dimensions, TTP implant dimensions, and the corresponding radiographic alignment about the forefoot, hindfoot, and ankle. Results: Fourteen patients, treated for AVN between 2016-2017, were identified in our cohort. Talar arc length and width were not found to be significantly changed, however talar height was significantly increased with use of TTP. Five alignment dimensions were measured (tibiotalar alignment, talar tilt angle, Boehler’s angle, talar declination angle, and Meary’s Angle), of which, only talar tilt angle was significantly changed. Instances of Meary’s angle correction were observed in cavus and planus foot deformity. Conclusion: This study represents the largest case series of TTP performed in the United States, and is the first to investigate the 3D printed TTP. As a proof-of-concept, 3D printed TTP was successful in restoring talar height and talar tilt in the setting of AVN. Additionally, the procedure maintained normal alignment in non-pathologic joints. Total talar prosthesis, based on our cohort, is a viable option to restore more normal anatomic alignment.

The Effect of Three Foot Types on the Achilles Tendon Lever Arm

Category: Hindfoot Introduction/Purpose: During locomotion, propulsion of the body is created by the force of the triceps surae complex as it is transmitted to the metatarsal heads. The amount and pattern of the resulting propulsion force highly depends on the moment arm of the Achilles tendon. To our knowledge, no data exists on how and to which extent position and morphology of the foot affects the moment arm of the Achilles tendon. The aim of this study was 1) to develop a method to determine the Achilles tendon moment arm, and 2) to calculate the Achilles tendon moment arm with the foot in different degrees of dorsi- and plantarflexion for 3 foot types (normal arched foot, pes planus, and pes cavus). Methods: 99 study participants with a healthy ankle joint (males, 40; females, 59; mean age 49 [range, 14 – 78] years) were included. Participants’ foot type was classified as a normal arched foot (n = 33), as pes planus (n = 33), or as pes cavus (n = 33) based on the calcaneal inclination angle (CI) (Figure 1). Besides the foot type, the foot length (FL), the calcaneal insertion of the Achilles tendon (ATI), the angle (a) between the line (L) connecting ATI with the center of rotation of the ankle (COR) and the horizontal line (L’) were measured on the lateral radiographs. The interrater reliabilities of measuring a on radiographs and on MRIs were compared. The lever arm of the Achilles tendon (L’calculated) was calculated as following (foot and tibia were regarded as two rigid segments; the influences of other muscles were neglected): L’calculated = cos(a - plantarflexion)*L Results: The interrater reliability of a was higher on radiographs (ICC = 0.84, [0.73 – 0.91]) than on MRIs (ICC = 0.61, [0.27 – 0.81]). The ICC comparing a measured on MRIs and radiographs was 0.63 [0.50-0.74]. There was no difference in FL between the three foot types (p = 0.199). However, the average a was significantly different (normal arched foot 31°, pes planus 24°, pes cavus 36°, p = 0.021), resulting in a statistically significant shorter Achilles tendon lever arm for pes cavus than for pes planus (p &lt; 0.0001) and normal arched feet (p = 0.006) in neutral position. The maximum lever arm for the three different foot types was reached at different degrees of plantarflexion (Figure 2). Conclusion: The assessment of the Achilles tendon lever arm using radiographs is reliable. The foot configuration determines the lever arm of the Achilles tendon for a given flexion position of the foot. It also determines the plantarflexion position where the Achilles tendon reaches the maximum of its lever arm. This has to be taken into consideration when planning surgeries that change a or L, as they may also result in changes of plantarflexion power.

Custom 3D-Printed Total Talar Prostheses Restore Normal Joint Anatomy Throughout the Hindfoot.

Third generation total talar prostheses (TTPs) are viable options for talar avascular necrosis (AVN) in the absence of neighboring joint pathology. The use of modern three-dimensional (3D) printing allows the production of custom implants that exactly mimic the patient's anatomy. The aim of this study is to determine the accuracy of 3D printing in reproducing a synthetic talus and, in doing so, restoring more normal anatomical relationships. We hypothesize that this mode of replication will restore and maintain normal radiographic alignment of the ankle, subtalar, and forefoot joints in the setting of talar AVN. A retrospective analysis was performed on all patients undergoing TTP implantation for the treatment of talar AVN between 2016 and 2017. Radiographic measurements were taken preoperatively and postoperatively to determine native talar dimensions, TTP implant dimensions, and the corresponding radiographic alignment about the forefoot, hindfoot, and ankle. A total of 14 patients were identified in our cohort. Talar arc length and width were not found to be significantly changed; however, talar height was significantly increased with use of TTP. Five alignment dimensions were measured, of which, only talar tilt angle was significantly changed. Instances of Meary's angle correction were observed in cavus and planus foot deformity. As a proof of concept, 3D-printed TTP was successful in restoring talar height and talar tilt in the setting of AVN. Additionally, the procedure maintained normal alignment in nonpathological joints. TTPs, based on our cohort, are a viable option to restore more normal anatomical alignment. Level IV: Case series.

Foot posture is associated with plantar pressure during gait: A comparison of normal, planus and cavus feet

BackgroundVariations in foot posture, such as pes planus (low medial longitudinal arch) or pes cavus (high medial longitudinal arch) are associated with some lower limb injuries. However, the mechanism that links foot posture to injury is not clear. Research question The aim of this study was to compare plantar pressure between healthy individuals with normal, planus or cavus feet. MethodsNinety-two healthy volunteers (aged 18 to 45) were classified as either normal (n = 35), pes planus (n = 31) or pes cavus (n = 26) based on the Foot Posture Index, Arch Index and normalised navicular height truncated. Barefoot walking trials were conducted using an emed®-x400 plantar pressure system (Novel GmbH, Munich, Germany). An 11 region mask was used that included the medial heel, lateral heel, midfoot, 1st, 2nd, 3rd, 4th and 5th metatarsophalangeal joints, hallux, 2nd toe, and the 3rd, 4th and 5th toes. Peak pressure, pressure-time integral, maximum force, force-time integral and contact area were calculated for each region. One way analyses of variance and effect sizes were used to compare the three foot posture groups. ResultsOverall, the largest differences were between the planus and cavus foot groups in forefoot pressure and force. In particular, peak pressures at the 4th and 5th MTPJs in the planus foot group were lower compared to the normal and cavus foot groups, and displayed the largest effect sizes. Significance This study confirms that foot posture does influence plantar pressures, and that each foot posture classification displays unique plantar pressure characteristics.

Use of high speed stereo radiography to assess the foot orthoses effectiveness in controlling midfoot posture during walking: A pilot study

BackgroundThe intent of this pilot study was to determine the feasibility of using high-speed stereo radiography (HSSR) to assess the effectiveness of footwear and foot orthoses in controlling the change in the position of the midfoot during walking in individuals with a flexible pes planus foot type. MethodsFour individuals (1 female; 3 male) with a mean age of 25 years (range 22–29) and a bilateral flexible pes planus foot type participated in the study. The HSSR system was used to measure 3-dimensional changes in the longitudinal arch angle (LAA) with each participant walking barefoot, shoe only and shoes with orthoses. ResultsThe HSSR system was found to be highly effective in measuring the change in the position of the midfoot, as measured using the LAA, when wearing footwear with or without foot orthoses. Based on an assessment of mean values, three out of the four participants demonstrated a change in the LAA as a result of using either shoes only or shoes with orthoses. The methodology used in this pilot study for assessing the effect of footwear and foot orthoses on the posture of the midfoot was highly effective with no side-effects noted by any of the study participants. ConclusionsFuture studies using the HSSR will require modifications to participant inclusion criteria as well as alterations to the data collection methodology. The HSSR system used in this study is feasible for use in larger cohort studies assessing footwear and foot orthosis effectiveness with the described modifications.

Centre of pressure characteristics in normal, planus and cavus feet

BackgroundThe aim of this study was to compare centre of pressure (COP) characteristics between healthy adults with normal, planus or cavus feet who were allocated to groups based on reliable foot posture measurement techniques.MethodsNinety-two healthy adult participants (aged 18 to 45) were recruited and classified as either normal (n = 35), pes planus (n = 31) or pes cavus (n = 26) based on Foot Posture Index, Arch Index and normalised navicular height truncated measurements. Barefoot walking trials were conducted using an emed®-x 400 plantar pressure system (Novel GmbH, Munich, Germany). Average, maximum, minimum and range (difference between maximum and minimum) values were calculated for COP velocity and lateral-medial force index during loading response, midstance, terminal stance and pre-swing phases of stance. The COP excursion index was also calculated. One-way analyses of variance were used to compare the three foot posture groups.ResultsThe cavus foot exhibited the slowest average and minimum COP velocity during terminal stance, but this pattern was reversed during pre-swing, when the cavus foot exhibited the fastest maximum COP velocity. The planus foot exhibited the smallest lateral medial force index range during terminal stance. There were no differences between the groups for COP excursion index.ConclusionThese findings indicate that there are differences in COP characteristics between foot postures, which may represent different mechanisms for generating force to facilitate forward progression of the body during the propulsive phases of gait.

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

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

Finite element simulation on posterior tibial tendinopathy: Load transfer alteration and implications to the onset of pes planus

BackgroundPosterior tibial tendinopathy is a challenging foot condition resulting in pes planus, which is difficult to diagnose in the early stage. Prior to the deformity, abnormal internal load transfer and soft tissue attenuation are anticipated. The objective of this study was to investigate the internal load transfer and strain of the ligaments with posterior tibial tendinopathy, and the implications to pes planus and other deformities. MethodsA three-dimensional finite element model of the foot and ankle was reconstructed from magnetic resonance images of a 28-year-old normal female. Thirty bones, plantar fascia, ligaments and tendons were reconstructed. With the gait analysis data of the model subject, walking stance was simulated. The onset of posterior tibial tendinopathy was resembled by unloading the tibialis posterior and compared to the normal condition. FindingsThe load transfer of the joints at the proximal medial column was weaken by posterior tibial tendinopathy, which was compromised by the increase along the lateral column and the intercuneiforms during late stance. Besides, the plantar tarsometatarsal and cuboideonavicular ligaments were consistently over-stretched during stance. Particularly, the maximum tensile strain of the plantar tarsometatarsal ligament was about 3-fold higher than normal at initial push-off. InterpretationPosterior tibial tendinopathy altered load transfer of the medial column and unbalanced the load between the proximal and distal side of the medial longitudinal arch. Posterior tibial tendinopathy also stretched the midfoot plantar ligaments that jeopardized midfoot stability, and attenuated the transverse arch. All these factors potentially contributed to the progress of pes planus and other foot deformities.