Comparative biomechanical effectiveness of over-the-counter devices for individuals with a flexible flatfoot secondary to forefoot varus

Effect of Different Foot Orthosis Inverted Angles on Walking Kinematics in Females with Flexible Flatfeet

Background

Although the inverted technique was shown to be more effective compared to other orthotic designs for the treatment of flatfeet, the biomechanical mechanisms underlying the therapeutic effect of the inverted angle orthoses is still unclear. Therefore, the aim of this study was to examine the effect of different inverted angles of foot orthoses on walking kinematics in females with flexible flatfeet.

Methods

Thirty-one female adults with flexible flatfeet aged 18-35 years old participated in this study. Kinematic data of the hip, knee, and ankle were collected via BTS motion-capture system during walking under three test conditions in random order: with shoes only; with 15° inverted orthoses; and with 25° inverted orthoses.

Results

Compared to the shoes only condition, both the 15° and 25° inverted orthotic conditions significantly decreased the maximum ankle plantarflexion angle during loading response, maximum ankle dorsiflexion angle during mid-stance, maximum ankle external rotation angle, and maximum ankle internal rotation angle. The maximum ankle plantarflexion angle at toe-off showed a significant decrease with the 25° inverted angle orthosis compared to both the 15° inverted angle and shoes only conditions. No significant differences were found in the knee kinematic variables, maximum hip extension angle, and maximum hip adduction angle between test conditions.

Conclusion

Using inverted orthoses at 15° and 25° inverted angles resulted in significant changes in ankle joint kinematics during walking in female adults with flexible flatfeet. A 25° inverted angle orthosis significantly decreased ankle plantarflexion during push-off, potentially impacting gait mechanics. This suggests that a smaller inverted angle may be more effective for managing flexible flatfeet in female adults.

The Soft Prefabricated Orthopedic Insole Decreases Plantar Pressure during Uphill Walking with Heavy Load Carriage

This study aimed to investigate the effect of varying the hardness of prefabricated orthopedic insoles on plantar pressure and muscle fatigue during uphill walking with a heavy backpack. Fifteen healthy male recreational athletes (age: 20.4 ± 1.0 years, height: 176.9 ± 5.7 cm, weight: 76.5 ± 9.0 kg) wore prefabricated orthopedic insoles with foot arch support; a heel cup with medium (MI), hard (HI), and soft (SI) relative hardnesses; and flat insoles (FI). They performed treadmill walking on uphill gradients with 25 kg backpacks. The plantar pressure and surface electromyographic activity were recorded separately, in 30 s and 6 min uphill treadmill walking trials, respectively. The HI, MI, and SI significantly decreased peak plantar pressure in the lateral heel compared to FI. The MI and SI significantly decreased the peak plantar pressure in the fifth metatarsal compared to FI. The MI significantly reduced the pressure–time integral in the lateral heel compared to FI. The HI significantly increased the peak plantar pressure and pressure–time integral in the toes compared to other insoles, and decreased the contact area in the metatarsal compared to SI. In conclusion, a prefabricated orthopedic insole made of soft material at the fore- and rearfoot, with midfoot arch support and a heel cup, may augment the advantages of plantar pressure distribution during uphill weighted walking.

Pie plano y tratamientos conservadores en adultos físicamente activos. Una revisión sistemática

El término pie plano es utilizado para describir cualquier anormalidad que causa el colapso del arco longitudinal medial del pie, cuando es sintomático condiciona el grado, tipo y calidad de actividad física que practique un adulto. Como objetivo nos planteamos revisar los tratamientos conservadores existentes para el pie plano en adultos jóvenes y de mediana edad. Siguiendo las directrices de la declaración PRISMA, se realizó una revisión sistemática de la literatura científica publicada sobre el pie plano y tratamientos conservadores. Los tratamientos conservadores para el pie plano son aplicados de manera aislada o en combinación, estos incluyen ejercicios de fortalecimiento, de estiramientos, uso de ortesis, aplicación de vendaje, modificación del calzado y estimulación eléctrica. Son requeridos estudios de tratamientos conservadores en adultos de mediana edad con pie plano sintomático que evalúen el efecto a corto y largo plazo de los actuales protocolos en poblaciones con diferente nivel de condición física. 

The Effect of Customized and Silicon Insoles on Mid- and Hindfoot in Adult Flexible Pes Planovalgus

BACKGROUND

Flexible flat foot or pes planovalgus is a common foot deformity, and silicone and customized insole are commonly used as a non-operative treatment modality of flexible planovalgus. However, there are inadequate data and limited evidence available regarding the immediate effects of their use in midfoot and hindfoot of adults. The aim of this study is to quantify and compare the radiological parameters immediately on weightbearing with silicon and customized insoles and without them to assess the effect on midfoot and hindfoot of the flexible planovalgus in adults.

METHODS

A total number of 11 (8 females and 3 males) subjects with flexible pes planovalgus deformity without any other foot deformity were included in the study. Each patient was assessed three times in a random sequence without and with use of either silicon insoles or customized insole. The radiographic parameters without insole, with silicon insole, and with customized insole conditions were calculated using online available computer software Kinovea.

RESULTS

One-way ANOVA analysis was performed between groups (without insole, with silicone insole and with customized insole). The hindfoot parameters depicted that calcaneal inclination angle (CIA) was significant increased (P = 0.000) and talar declination angle (TDA) was significantly decreased (P = 0.003) only with the use of customized insole compared to without insole. The midfoot parameters depicted that the first metatarsal angle (FMA) and talonavicular coverage angle (TCA) were significantly lower with customized insole (P = 0.00) as compared to other two groups and significantly lower with silicone insole (P = 0.00) as compared to without insole group.

CONCLUSION

The results imply that the compressibility of the insole material affects the forefoot and hindfoot biomechanics differently. This study concludes that silicone insole affects only the midfoot which bears 45% of bodyweight and customized insole affects both midfoot and more importantly the hindfoot which bears 55% of bodyweight.

Different Design Feature Combinations of Flatfoot Orthosis on Plantar Fascia Strain and Plantar Pressure: A Muscle-Driven Finite Element Analysis With Taguchi Method

Customized foot orthosis is commonly used to modify foot posture and relieve foot pain for adult acquired flexible flatfoot. However, systematic investigation of the influence of foot orthotic design parameter combination on the internal foot mechanics remains scarce. This study aimed to investigate the biomechanical effects of different combinations of foot orthoses design features through a muscle-driven flatfoot finite element model. A flatfoot-orthosis finite element model was constructed by considering the three-dimensional geometry of plantar fascia. The plantar fascia model accounted for the interaction with the bulk soft tissue. The Taguchi approach was adopted to analyze the significance of four design factors combination (arch support height, medial posting inclination, heel cup height, and material stiffness). Predicted plantar pressure and plantar fascia strains in different design combinations at the midstance instant were reported. The results indicated that the foot orthosis with higher arch support (45.7%) and medial inclination angle (25.5%) effectively reduced peak plantar pressure. For the proximal plantar fascia strain, arch support (41.8%) and material stiffness (37%) were strong influencing factors. Specifically, higher arch support and softer material decreased the peak plantar fascia strain. The plantar pressure and plantar fascia loading were sensitive to the arch support feature. The proposed statistics-based finite element flatfoot model could assist the insole optimization and evaluation for individuals with flatfoot.

Foot orthoses for treating paediatric flat feet

BACKGROUND

Paediatric flat feet are a common presentation in primary care; reported prevalence approximates 15%. A minority of flat feet can hurt and limit gait. There is no optimal strategy, nor consensus, for using foot orthoses (FOs) to treat paediatric flat feet.

OBJECTIVES

To assess the benefits and harms of foot orthoses for treating paediatric flat feet.

SEARCH METHODS

We searched CENTRAL, MEDLINE, and Embase to 01 September 2021, and two clinical trials registers on 07 August 2020.

SELECTION CRITERIA

We identified all randomised controlled trials (RCTs) of FOs as an intervention for paediatric flat feet. The outcomes included in this review were pain, function, quality of life, treatment success, and adverse events. Intended comparisons were: any FOs versus sham, any FOs versus shoes, customised FOs (CFOs) versus prefabricated FOs (PFOs).

DATA COLLECTION AND ANALYSIS

We followed standard methods recommended by Cochrane.

MAIN RESULTS

We included 16 trials with 1058 children, aged 11 months to 19 years, with flexible flat feet. Distinct flat foot presentations included asymptomatic, juvenile idiopathic arthritis (JIA), symptomatic and developmental co-ordination disorder (DCD). The trial interventions were FOs, footwear, foot and rehabilitative exercises, and neuromuscular electrical stimulation (NMES). Due to heterogeneity, we did not pool the data. Most trials had potential for selection, performance, detection, and selective reporting bias. No trial blinded participants. We present the results separately for asymptomatic (healthy children) and symptomatic (children with JIA) flat feet. The certainty of evidence was very low to low, downgraded for bias, imprecision, and indirectness. Three comparisons were evaluated across trials: CFO versus shoes; PFO versus shoes; CFO versus PFO. Asymptomatic flat feet 1. CFOs versus shoes (1 trial, 106 participants): low-quality evidence showed that CFOs result in little or no difference in the proportion without pain (10-point visual analogue scale (VAS)) at one year (risk ratio (RR) 0.85, 95% confidence interval (CI) 0.67 to 1.07); absolute decrease (11.8%, 95% CI 4.7% fewer to 15.8% more); or on withdrawals due to adverse events (RR 1.05, 95% CI 0.94 to 1.19); absolute effect (3.4% more, 95% CI 4.1% fewer to 13.1% more). 2. PFOs versus shoes (1 trial, 106 participants): low to very-low quality evidence showed that PFOs result in little or no difference in the proportion without pain (10-point VAS) at one year (RR 0.94, 95% CI 0.76 to 1.16); absolute effect (4.7% fewer, 95% CI 18.9% fewer to 12.6% more); or on withdrawals due to adverse events (RR 0.99, 95% CI 0.79 to 1.23). 3. CFOs versus PFOs (1 trial, 108 participants): low-quality evidence found no difference in the proportion without pain at one year (RR 0.93, 95% CI 0.73 to 1.18); absolute effect (7.4% fewer, 95% CI 22.2% fewer to 11.1% more); or on withdrawal due to adverse events (RR 1.00, 95% CI 0.90 to 1.12). Function and quality of life (QoL) were not assessed. Symptomatic (JIA) flat feet 1. CFOs versus shoes (1 trial, 28 participants, 3-month follow-up): very low-quality evidence showed little or no difference in pain (0 to 10 scale, 0 no pain) between groups (MD -1.5, 95% CI -2.78 to -0.22). Low-quality evidence showed improvements in function with CFOs (Foot Function Index - FFI disability, 0 to 100, 0 best function; MD -18.55, 95% CI -34.42 to -2.68), child-rated QoL (PedsQL, 0 to 100, 100 best quality; MD 12.1, 95% CI -1.6 to 25.8) and parent-rated QoL (PedsQL MD 9, 95% CI -4.1 to 22.1) and little or no difference between groups in treatment success (timed walking; MD -1.33 seconds, 95% CI -2.77 to 0.11), or withdrawals due to adverse events (RR 0.58, 95% CI 0.11 to 2.94); absolute difference (9.7% fewer, 20.5 % fewer to 44.8% more). 2. PFOs versus shoes (1 trial, 25 participants, 3-month follow-up): very low-quality evidence showed little or no difference in pain between groups (MD 0.02, 95% CI -1.94 to 1.98). Low-quality evidence showed no difference between groups in function (FFI-disability MD -4.17, 95% CI -24.4 to 16.06), child-rated QoL (PedsQL MD -3.84, 95% CI -19 to 11.33), or parent-rated QoL (PedsQL MD -0.64, 95% CI -13.22 to 11.94). 3. CFOs versus PFOs (2 trials, 87 participants): low-quality evidence showed little or no difference between groups in pain (0 to 10 scale, 0 no pain) at 3 months (MD -1.48, 95% CI -3.23 to 0.26), function (FFI-disability MD -7.28, 95% CI -15.47 to 0.92), child-rated QoL (PedsQL MD 8.6, 95% CI -3.9 to 21.2), or parent-rated QoL (PedsQL MD 2.9, 95% CI -11 to 16.8).

AUTHORS' CONCLUSIONS

Low to very low-certainty evidence shows that the effect of CFOs (high cost) or PFOs (low cost) versus shoes, and CFOs versus PFOs on pain, function and HRQoL is uncertain. This is pertinent for clinical practice, given the economic disparity between CFOs and PFOs. FOs may improve pain and function, versus shoes in children with JIA, with minimal delineation between costly CFOs and generic PFOs. This review updates that from 2010, confirming that in the absence of pain, the use of high-cost CFOs for healthy children with flexible flat feet has no supporting evidence, and draws very limited conclusions about FOs for treating paediatric flat feet. The availability of normative and prospective foot development data, dismisses most flat foot concerns, and negates continued attention to this topic. Attention should be re-directed to relevant paediatric foot conditions, which cause pain, limit function, or reduce quality of life. The agenda for researching asymptomatic flat feet in healthy children must be relegated to history, and replaced by a targeted research rationale, addressing children with indisputable foot pathology from discrete diagnoses, namely JIA, cerebral palsy, congenital talipes equino varus, trisomy 21 and Charcot Marie Tooth. Whether research resources should continue to be wasted on studying flat feet in healthy children that do not hurt, is questionable. Future updates of this review will address only relevant paediatric foot conditions.

Foot orthoses for treating paediatric flat feet

BACKGROUND

Paediatric flat feet are a common presentation in primary care; reported prevalence approximates 15%. A minority of flat feet can hurt and limit gait. There is no optimal strategy, nor consensus, for using foot orthoses (FOs) to treat paediatric flat feet.

OBJECTIVES

To assess the benefits and harms of foot orthoses for treating paediatric flat feet.

SEARCH METHODS

We searched CENTRAL, MEDLINE, and Embase to 01 September 2021, and two clinical trials registers on 07 August 2020.

SELECTION CRITERIA

We identified all randomised controlled trials (RCTs) of FOs as an intervention for paediatric flat feet. The outcomes included in this review were pain, function, quality of life, treatment success, and adverse events. Intended comparisons were: any FOs versus sham, any FOs versus shoes, customised FOs (CFOs) versus prefabricated FOs (PFOs).

DATA COLLECTION AND ANALYSIS

We followed standard methods recommended by Cochrane.

MAIN RESULTS

We included 16 trials with 1058 children, aged 11 months to 19 years, with flexible flat feet. Distinct flat foot presentations included asymptomatic, juvenile idiopathic arthritis (JIA), symptomatic and developmental co-ordination disorder (DCD). The trial interventions were FOs, footwear, foot and rehabilitative exercises, and neuromuscular electrical stimulation (NMES). Due to heterogeneity, we did not pool the data. Most trials had potential for selection, performance, detection, and selective reporting bias. No trial blinded participants. We present the results separately for asymptomatic (healthy children) and symptomatic (children with JIA) flat feet. The certainty of evidence was very low to low, downgraded for bias, imprecision, and indirectness. Three comparisons were evaluated across trials: CFO versus shoes; PFO versus shoes; CFO versus PFO. Asymptomatic flat feet 1. CFOs versus shoes (1 trial, 106 participants): low-quality evidence showed that CFOs result in little or no difference in the proportion without pain (10-point visual analogue scale (VAS)) at one year (risk ratio (RR) 0.85, 95% confidence interval (CI) 0.67 to 1.07); absolute decrease (11.8%, 95% CI 4.7% fewer to 15.8% more); or on withdrawals due to adverse events (RR 1.05, 95% CI 0.94 to 1.19); absolute effect (3.4% more, 95% CI 4.1% fewer to 13.1% more). 2. PFOs versus shoes (1 trial, 106 participants): low to very-low quality evidence showed that PFOs result in little or no difference in the proportion without pain (10-point VAS) at one year (RR 0.94, 95% CI 0.76 to 1.16); absolute effect (4.7% fewer, 95% CI 18.9% fewer to 12.6% more); or on withdrawals due to adverse events (RR 0.99, 95% CI 0.79 to 1.23). 3. CFOs versus PFOs (1 trial, 108 participants): low-quality evidence found no difference in the proportion without pain at one year (RR 0.93, 95% CI 0.73 to 1.18); absolute effect (7.4% fewer, 95% CI 22.2% fewer to 11.1% more); or on withdrawal due to adverse events (RR 1.00, 95% CI 0.90 to 1.12). Function and quality of life (QoL) were not assessed. Symptomatic (JIA) flat feet 1. CFOs versus shoes (1 trial, 28 participants, 3-month follow-up): very low-quality evidence showed little or no difference in pain (0 to 10 scale, 0 no pain) between groups (MD -1.5, 95% CI -2.78 to -0.22). Low-quality evidence showed improvements in function with CFOs (Foot Function Index - FFI disability, 0 to 100, 0 best function; MD -18.55, 95% CI -34.42 to -2.68), child-rated QoL (PedsQL, 0 to 100, 100 best quality; MD 12.1, 95% CI -1.6 to 25.8) and parent-rated QoL (PedsQL MD 9, 95% CI -4.1 to 22.1) and little or no difference between groups in treatment success (timed walking; MD -1.33 seconds, 95% CI -2.77 to 0.11), or withdrawals due to adverse events (RR 0.58, 95% CI 0.11 to 2.94); absolute difference (9.7% fewer, 20.5 % fewer to 44.8% more). 2. PFOs versus shoes (1 trial, 25 participants, 3-month follow-up): very low-quality evidence showed little or no difference in pain between groups (MD 0.02, 95% CI -1.94 to 1.98). Low-quality evidence showed no difference between groups in function (FFI-disability MD -4.17, 95% CI -24.4 to 16.06), child-rated QoL (PedsQL MD -3.84, 95% CI -19 to 11.33), or parent-rated QoL (PedsQL MD -0.64, 95% CI -13.22 to 11.94). 3. CFOs versus PFsO (2 trials, 87 participants): low-quality evidence showed little or no difference between groups in pain (0 to scale, 0 no pain) at 3 months (MD -1.48, 95% CI -3.23 to 0.26), function (FFI-disability MD -7.28, 95% CI -15.47 to 0.92), child-rated QoL (PedsQL MD 8.6, 95% CI -3.9 to 21.2), or parent-rated QoL (PedsQL MD 2.9, 95% CI -11 to 16.8).

AUTHORS' CONCLUSIONS

Low to very low-certainty evidence shows that the effect of CFOs (high cost) or PFOs (low cost) versus shoes, and CFOs versus PFOs on pain, function and HRQoL is uncertain. This is pertinent for clinical practice, given the economic disparity between CFOs and PFOs. FOs may improve pain and function, versus shoes in children with JIA, with minimal delineation between costly CFOs and generic PFOs. This review updates that from 2010, confirming that in the absence of pain, the use of high-cost CFOs for healthy children with flexible flat feet has no supporting evidence, and draws very limited conclusions about FOs for treating paediatric flat feet. The availability of normative and prospective foot development data, dismisses most flat foot concerns, and negates continued attention to this topic. Attention should be re-directed to relevant paediatric foot conditions, which cause pain, limit function, or reduce quality of life. The agenda for researching asymptomatic flat feet in healthy children must be relegated to history, and replaced by a targeted research rationale, addressing children with indisputable foot pathology from discrete diagnoses, namely JIA, cerebral palsy, congenital talipes equino varus, trisomy 21 and Charcot Marie Tooth. Whether research resources should continue to be wasted on studying flat feet in healthy children that do not hurt, is questionable. Future updates of this review will address only relevant paediatric foot conditions.

Understanding the role of foot biomechanics on regional foot orthosis deformation in flatfoot individuals during walking

BACKGROUND

Foot orthoses (FOs) are one of the most common interventions to restore normal foot mechanics in flatfoot individuals. New technologies have made it possible to deliver customized FOs with complex designs for potentially better functionalities. However, translating the individuals' biomechanical needs into the design of customized FOs is not yet fully understood.

RESEARCH QUESTION

Our objective was to identify whether the deformation of customized FOs is related to foot kinematics and plantar pressure during walking.

METHODS

The kinematics of multi-segment foot and FOs contour were recorded together with plantar pressure in 17 flatfoot individuals while walking with customized FOs. The deformation of FOs surface was predicted from its contour kinematics using an artificial neural network. Plantar pressure map and deformation were divided into five anatomically based regions defined by the corresponding foot segments. Forward stepwise linear mixed models were built for each of the four gait phases to determine the feet-FOs interaction.

RESULTS

It was observed that some associations existed between foot kinematics and pressure with regional FOs deformation. From heel-strike to foot-flat, longitudinal arch angle was associated with FOs deformation in forefoot. From foot-flat to midstance, rearfoot eversion accounted for variation in the deformation of medial FOs regions, and forefoot abduction for the lateral regions. From midstance to heel-off, rearfoot eversion, longitudinal arch angle, and plantar pressure played significant role in deformation. Finally, from heel-off to toe-off, forefoot adduction affected the deformation of forefoot and midfoot.

SIGNIFICANCE

This study provides guidelines for designing customized FOs. Flatfoot individuals with excessive rearfoot eversion or very flexible medial arches require more support on medial FOs regions, while the ones with excessive forefoot abduction need the support on lateral regions. However, a compromise should be made between the level of support and the level of increase in plantar pressure to avoid stress on foot structures.

Is there a dose-response of medial wedge insoles on lower limb biomechanics in people with pronated feet during walking and running?

BACKGROUND

Although the effects of medial wedge insoles on lower limb biomechanics have been investigated, information about the effects of different magnitudes of medial posting is still lacking.

RESEARCH QUESTION

What are the dose-response effects of medial wedge insoles with postings varying between 0 °, 3 °, 6 °, and 9 ° of inclination on the lower limb biomechanics during walking and running in individuals with pronated feet?

METHODS

Sixteen participants with an FPI ≥ 6 were recruited. Four arch-supported insole conditions with varying degrees of medial heel wedge were tested (0°, 3°, 6°, and 9°). A 3D motion analysis system with force plates was used to obtain the kinetics and kinematics of walking and running at self-selected speeds. To compare the ankle, knee, and hip angles and moments among conditions, a time series analysis was performed using Statistical Parametric Mapping (SPM).

RESULTS

A reduction in ankle eversion angle was observed during walking for all insoles. For running, the 6° and 9° insoles decreased the ankle eversion angle during early stance and increased this angle during the propulsive phase. A decrease in ankle eversion moment was observed in walking and running for 6° and 9° insoles. An increase in knee adduction moment occurred in walking and running for all insoles. For hip, the 6° and 9° insoles showed, during walking, a decrease in hip adduction angle and an increase in hip adduction and external rotation moments. For most variables, statistical differences were found for a greater period across the stance phase as the medial wedge increased, except for ankle eversion moment and hip external rotation moment during walking.

SIGNIFICANCE

The biomechanical effects over the time series for many of the parameters increased with the addition of insole inclination, showing a dose-response effect of medial wedge insoles on the lower limb biomechanics during walking and running in adults with excessive foot pronation.

Extrinsic foot muscle forces and joint contact forces in flexible flatfoot adult with foot orthosis: A parametric study of tibialis posterior muscle weakness

BACKGROUND

The posterior tibialis tendon dysfunction (PTTD) is typically associated with progressive flatfoot deformity, which could be alleviated with foot orthosis. However, the evaluation of tibialis posterior (TP) weakness on lower limb mechanics of flatfoot adults with foot orthoses is scarce and requires further investigation.

RESEARCH QUESTION

This study aimed to examine the effects of TP weakness on lower limb mechanics in flatfoot adults with foot orthosis through gait analysis and musculoskeletal modelling.

METHODS

Fifteen young adults with flatfoot were recruited from University to perform a gait experiment with and without foot orthoses. Data collected from the motion capture system were used to drive the musculoskeletal modelling for the estimation of the joint force and extrinsic muscle forces of the lower limb. A parametric analysis was conducted by adjusting the TP muscle strength from 40 % to 100 %. Two-way repeated measures ANOVA was used to compare the peak extrinsic foot muscle forces and joint forces among different levels of TP weakness and insole conditions.

RESULTS

TP weakness significantly increased ankle joint force superoinferiorly (F = 125.9, p < 0.001) and decreased anteroposteriorly (F = 125.9, p < 0.001), in addition to a significant increase in the muscle forces of flexor hallucis longus (p < 0.001) and flexor digitorum longus (p < 0.001). Besides, the foot orthosis significantly reduced most peak muscle forces whilst significantly reduced the second peak knee force and peak ankle force compared to the control condition (F = 8.79-30.9, p < 0.05).

SIGNIFICANCE

The increased extrinsic foot muscle forces (flexor hallucis longus and flexor digitorum longus) and ankle joint forces in the TP weakness condition indicated that TP weakness may induce compensatory muscle activation and attenuated joint load. The abnormal muscle and joint mechanics in flatfoot adults with TP weakness might be restored by the orthosis.

Major factors influencing rearfoot external eversion moment during barefoot walking

BACKGROUND

Excessive rearfoot eversion motion during walking has been considered as a risk factor for lower limb chronic injuries. External moment due to ground reaction force (GRF) is the essential cause by which the rearfoot is passively everted during walking.

RESEARCH QUESTION

This study aims to identify the key factors influencing the rearfoot external eversion moments due to the GRF during walking.

METHODS

From 3-D foot coordinates and GRF data of 29 healthy participants during walking, the rearfoot external eversion moments due to the GRF and factors composing the moment (height of the ankle joint center, mediolateral GRF, mediolateral distance of the center of pressure relative to the ankle joint center in the transverse plane, vertical GRF) were computed.

RESULTS

The mediolateral GRF was a key factor influencing the magnitude of the rearfoot external eversion moment just after foot contact, with which pre-contact medial foot velocity was significantly correlated. During the subsequent support phase, the mediolateral distance of the center of pressure (the application point of the vertical GRF) relative to the ankle joint center was also found to be another determinant of the magnitude of the rearfoot external eversion moment.

SIGNIFICANCE

We succeeded in demonstrating the specific factors that most likely explain the magnitude of the rearfoot external eversion moment during initial contact and the subsequent support phase during walking. Based on the findings, specific measures to suppress the rearfoot external eversion moment could be proposed.

Biomechanical Evaluation and Strength Test of 3D-Printed Foot Orthoses

Foot orthoses (FOs) are commonly used as interventions for individuals with flatfoot. Advances in technologies such as three-dimensional (3D) scanning and 3D printing have facilitated the fabrication of custom FOs. However, few studies have been conducted on the mechanical properties and biomechanical effects of 3D-printed FOs. The purposes of this study were to evaluate the mechanical properties of 3D-printed FOs and determine their biomechanical effects in individuals with flexible flatfoot. During mechanical testing, a total of 18 FO samples with three orientations (0°, 45°, and 90°) were fabricated and tested. The maximum compressive load and stiffness were calculated. During a motion capture experiment, 12 individuals with flatfoot were enrolled, and the 3D-printed FOs were used as interventions. Kinematic and kinetic data were collected during walking by using an optical motion capture system. A one-way analysis of variance was performed to compare the mechanical parameters among the three build orientations. A paired t-test was conducted to compare the biomechanical variables under two conditions: walking in standard shoes (Shoe) and walking in shoes embedded with FOs (Shoe+FO). The results indicated that the 45° build orientation produced the strongest FOs. In addition, the maximum ankle evertor and external rotator moments under the Shoe+FO condition were significantly reduced by 35% and 16%, respectively, but the maximum ankle plantar flexor moments increased by 3%, compared with the Shoe condition. No significant difference in ground reaction force was observed between the two conditions. This study demonstrated that 3D-printed FOs could alter the ankle joint moments during gait.

Biomechanical Effect of Foot Orthoses on Rearfoot Motions and Joint Moment Parameters in Patients with Flexible Flatfoot

Background

The effect of foot orthoses in terms of kinematics and kinetics during walking could be affected on different geometrical designs. Therefore, the purpose of this study was to compare the biomechanical and clinical effects of 3 different insoles on rearfoot motion (RFM) and ankle joint moment parameters.

Material/Methods

Twenty eight university students with flexible flatfoot were recruited for this study, and each participant was asked to wear 3 different insoles: normal insole without arch support function, type A insole with only arch support function, and type B insole with both arch support and cushion pads for shock absorbing functions. Three-dimensional motion analysis was performed to compute the ranges and peak orientation angles of RFM and ankle joint moment parameters.

Results

The type A and type B insoles exhibited significantly smaller peak everted position and evertor moment than the normal insole. Also, the type A insole showed significantly smaller range of rearfoot motion in the longitudinal axis and the length of MA (moment arm) in the mediolateral axis than the normal insole.

Conclusions

The use of the type A insole using arch support function was induced to promote a cautious gait pattern associated with a relatively lower potential risk compared to the normal insole. The type A and type B insoles could be important to positively reduce the possibility of injury. Also, the smaller length of MA in the type A insole might have a contribution to the decrease of ankle joint evertor moment.

Mechanical factors affecting the foot eversion moment during the stance phase of running in non-rearfoot strikers

This study aimed to identify the primary factors that induce rearfoot external eversion moments due to ground reaction force (GRF) in non-rearfoot strikers. The data were compared with those of rearfoot strikers. Totally, 11 healthy males who were habitually non-rearfoot strikers ran barefoot. Rearfoot external eversion/inversion moments due to GRF (Mtot) were decomposed into two components based on mediolateral (Mxy) and vertical (Mz) GRFs. The height of the ankle joint centre and the mediolateral distance from the centre of pressure (COP) to the ankle joint centre (a_cop) were calculated as the lever arms to the Mxy and Mz components. Just after foot contact, non-rearfoot strikers demonstrated a significantly larger Mz, which was strongly dependent on a_cop and produced most of the Mtot, whereas Mxy dominated Mtot in rearfoot strikers. During the consecutive loading phase, non-rearfoot strikers demonstrated a significantly larger Mxy, which was strongly dependent on the mediolateral GRF and substantially contributed to Mtot, unlike the rearfoot strikers, whose Mtot was almost dominated by Mz during the loading phase. It was found that since the factor of generating the moment differs depending on the foot contact pattern, the strategies for suppressing the moment may be different for each foot contact pattern.

Effect of foot orthosis design on lower limb joint kinematics and kinetics during walking in flexible pes planovalgus: A systematic review and meta-analysis

BACKGROUND

Foot orthoses are commonly used for the management of excessive foot pronation in people with pes planovalgus. However, results are inconsistent due to variability in orthosis geometrical designs. This systematic review with meta-analysis aimed to classify and investigate the effects of foot orthoses, based on their design, in terms of lower limb kinematics and kinetics in people with pes planovalgus.

METHODS

Electronic databases were searched up until August 2017. Peer-reviewed journal studies including adult participants with flexible pes planovalgus and reporting kinematics and kinetics effects of foot orthoses during walking were included and classified based on the orthosis design. Eleven studies were retained and assessed according to methodological (mean 76.1%; range [63.2%-84.2%] - high) and biomechanical (mean 71.6%; range [44.4%-100%] - moderate) qualities. Meta-analysis was performed by calculating the effect size, using standardized mean differences, between control and orthotics conditions.

FINDINGS

Meta-analysis revealed less rearfoot eversion with the use of foot orthoses including medial forefoot or both forefoot and rearfoot posting. However, no significant effect of foot orthoses with arch support and neutral rearfoot posting to control excessive foot pronation were found. In terms of kinetics, none of the foot orthoses showed effects.

INTERPRETATION

Using medial posting is the most effective foot orthotic feature to reduce the peak rearfoot eversion and to control excessive foot pronation. Nevertheless, heterogeneity between study protocols contributes to the low evidences of foot orthoses effects on kinematics and kinetics during walking in people with pes planovalgus.

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.

Analysis of medial deviation of center of pressure after initial heel contact in forefoot varus

BACKGROUND/PURPOSE

After initial heel contact, the rearfoot everts and causes medial deviation of the center of pressure (CoP). Although rearfoot angle in single-limb stance has been associated with forefoot varus (FV) ≥ 8°, medial CoP deviation has not.

METHODS

After 12 participants with FV < 8° (neutral group) and 11 participants with FV ≥ 8° (FV group) stepped one heel initially onto an array of pressure sensors parallel to its Y coordinate axis, when the CoP of array deviated most medially, the X coordinate of the CoP of each row was calculated to find the most medial CoP of the row. Starting since the row with the most medial CoP just began to have the same sensors with pressures >0 kPa as when it had the most medial CoP, the medial deviations of the CoP of the array, the most medial CoP of the row, and its relative position in the row (CoP%), were compared between neutral and FV groups.

RESULTS

The medial deviations of the most medial CoP of the row (1.1 ± 0.6 vs. 1.6 ± 0.3 mm, p = 0.049) and CoP% (2.9 ± 1.4 vs. 4.2 ± 1.1%, p = 0.023) were significantly different between neutral and FV groups, whereas that of the CoP of the array (1.1 ± 0.6 vs. 1.4 ± 0.6 mm, p = 0.36) was not.

CONCLUSION

The most medial CoP of the row and CoP% detected increased medial CoP deviation in FV ≥ 8°, and may be applied to other clinical conditions where rearfoot angle and CoP of the array after initial heel contact cannot detect significant differences.

Foot orthoses for adults with flexible pes planus: a systematic review

BACKGROUND

Foot orthoses are widely used in the management of flexible pes planus, yet the evidence to support this intervention has not been clearly defined. This systematic review aimed to critically appraise the evidence for the use of foot orthoses for flexible pes planus in adults.

METHODS

Electronic databases (Medline, CINAHL, Cochrane, Web of science, SportDiscus, Embase) were systematically searched in June 2013 for randomised controlled, controlled clinical and repeated measure trials where participants had identified flexible pes planus using a validated and reliable measure of pes planus and the intervention was a rigid or semi-rigid orthoses with the comparison being a no-orthoses (shoes alone or flat non-posted insert) condition. Outcomes of interest were foot pain, rearfoot kinematics, foot kinetics and physical function.

RESULTS

Of the 2,211 articles identified by the searches, 13 studies met the inclusion criteria; two were randomised controlled trials, one was a controlled trial and 10 were repeated measure studies. Across the included studies, 59 relevant outcome measures were reported with 17 calculated as statistically significant large or medium effects observed with use of foot orthoses compared to the no orthoses condition (SMD range 1.13 to -4.11).

CONCLUSIONS

No high level evidence supported the use of foot orthoses for flexible pes planus. There is good to moderate level evidence that foot orthoses improve physical function (medial-lateral sway in standing (level II) and energy cost during walking (level III)). There is low level evidence (level IV) that foot orthoses improve pain, reduce rearfoot eversion, alter loading and impact forces; and reduce rearfoot inversion and eversion moments in flexible pes planus. Well-designed randomised controlled trials that include appropriate sample sizes, clinical cohorts and involve a measure of symptom change are required to determine the efficacy of foot orthoses to manage adult flexible pes planus.