Muscle strength and foot pressure vary depending on the type of foot pain

This study compared muscle strength and foot pressure among patients with metatarsalgia, patients with plantar fasciitis, and healthy controls. A total of 31 patients with foot pain (14 metatarsalgia and 17 plantar fasciitis) and 29 healthy controls participated in the study. The strengths of the plantar flexor and hip muscles were measured using isokinetic and handheld dynamometers, respectively. Foot pressure parameters, including the pressure-time integral (PTI) and foot arch index (AI), were assessed using pedobarography. Compared with the healthy control group, plantar flexor strength was significantly reduced in the affected feet of the metatarsalgia and plantar fasciitis groups (F = 0.083, all p < 0.001); however, hip strength was significantly decreased only in the affected feet of the metatarsalgia group (F = 20.900, p < 0.001). Plantar flexor (p < 0.001) and hip (p = 0.004) strength were significantly lower in the metatarsalgia group than in the plantar fasciitis group. The PTI was lower in the forefeet of the affected feet in the metatarsalgia (p < 0.001) and plantar fasciitis (p = 0.004) groups. Foot AI (p < 0.001) was significantly reduced only in the metatarsalgia group. These results suggest the need to consider the evaluation of muscle strength and foot pressure in both feet for the diagnosis and treatment of foot pain.

The importance of foot posture when recording lower leg electromyography when walking in non-textured and textured foot orthoses

Foot posture describes the anatomical variance in an individual's overall foot shape, an important consideration in the provision of foot orthoses. Current orthoses designs could be optimized by considering the topographical organization of cutaneous mechanoreceptors. Currently, the effect of foot orthoses designs to enhance skin stimulation across different anatomical foot posture remains unknown. Thus, the purpose of this study was to investigate how foot posture variance modulates lower leg muscle activity when walking in non-textured orthoses and in textured orthoses which facilitates cutaneous mechanoreceptors under five different regions of the foot sole. Fifty-one (51) healthy young adults were subdivided by the Foot Posture Index and completed level walking trials wearing non-textured and textured foot orthoses. Surface and fine-wire electromyography (EMG) recorded muscle activity in 8 lower leg muscles. Statistically significant interactions were observed in each muscle's average EMG across textured location and Foot Posture Index score. For example, in pes cavus compared to pes planus feet, texture under the calcaneus generated greater aEMG of the tibialis anterior (44.9 mV ± 22.7 mV to 30.9 mV ± 11.4 mV) medial gastrocnemius (26.1 mV ± 16.7 mV to 17.5 mV ± 6.0 mV), and tibialis posterior (84.4 mV ± 77.1 mV to 64.4 mV ± 44.5 mV) muscles. This study demonstrates that lower leg muscle activity is modulated across the foot posture spectrum wearing non-textured and textured foot orthoses. Furthermore, in the development of new orthoses designs, specifically with texture, foot posture remains an important consideration when clinicians interpret EMG results and academics are designing new experimental protocols.

Is Morton's neuroma in a pes planus or pes cavus foot lead to differences in pressure distribution and gait parameters?

Morton's neuroma (MN) is a compressive neuropathy of the common digital plantar nerve causing forefoot pain. Foot posture and altered plantar pressure distribution have been identified as predispoing factors, however no studies have compared individuls with different foot postures with MN. Thus, we aimed to compare the effect of MN on spatiotemporal gait parameters and foot-pressure distribution in individuals with pes planus and pes cavus. Thirty-eight patients with unilateral MN were evaluated between June and August 2021. Nineteen patients with bilateral pes planus and 19 age and gender-matched patients with pes cavus who had no prior surgery were recruited. A Zebris FDM-THM-S treadmill system (Zebris Medical GmbH, Germany) was used to evaluate step length, stride length, step width, step time, stride time, cadence, velocity, foot-pressure distribution, force and whole stance phase, loading response, mid stance, pre-swing and swing phase percentages. There were no significant differences between the groups in spatiotemporal gait parameters (p > 0.05). Patients with pes planus displayed the following results for step length (49.36 ± 8.38), step width (9.05 ± 2.12), stance phase percentage (65.92 ± 2.11), swing phase percentage (34.08 ± 2.12), gait speed (2.96 ± 0.55), and cadence (100.57 ± 8.84). In contrast, patients with pes cavus displayed the following results for step length (49.06 ± 8.37), step width (8.10 ± 2.46), stance phase percentage (64.96 ± 1.61), swing phase percentage (34.79 ± 1.60), gait speed (2.95 ± 0.65), and cadence (99.73 ± 13.81). Foot-pressure distribution values showed no differences were detected in force, forefoot, and rearfoot pressure distribution, except for midfoot force (p < 0.05). The forefoot, midfoot, and rearfoot pressure values for the pronated group were 32.14 ± 10.90, 13.80 ± 3.03, and 22.78 ± 5.10, and for the supinated group were 33.50 ± 11.49, 14.23 ± 3.11 and 24.93 ± 6.52. MN does not significantly affect spatiotemporal gait parameters or foot-pressure distribution in patients with pes cavus or pes planus.

Correlation between the foot pressure index and the prevalence of plantar hyperkeratosis

BACKGROUND

Plantar hyperkeratosis (HK) is a very prevalent foot lesion formed due to an alteration in the keratinisation process, thereby increasing keratynocites and accumulating multiple layers of the stratum corneum that leads to plantar pain. As foot shape and plantar pressures is related with their appearance, the aim of this study is to examine how foot posture and plantar pressure influence the appearance of this keratopathy.

MATERIAL AND METHODS

On a sample of 400 subjects (201 men and 199 women), the plantar pressures were evaluated by the Footscan® platform in 10 zones. The clinical exploration consisted in the valuation of the Foot Posture Index (FPI), and the assessment of the appeerance (and location) or not of plantar calluses or hyperkeratosis.

RESULTS

6.3% of the feet presented a highly supinated FPI, 15.5% were supinated, 57.3% corresponded to neutral, 17.3% were pronated and 3.8% were highly pronated. The participants with HK on the hallux, on the 1st, 2nd, 3rd or 5th MTH or on the lateral heel had a significantly higher pressure index (p < 0.001), ranging from 24.3 to 44% higher than those with no such alteration. Of the highly pronated feet, 66.7% presented HK in the hallux, while 32.3% of the supinated feet and 60% of the highly supinated feet presented it beneath the first MTH.

CONCLUSION

Foot posture influences the appearance of HK, though its association with plantar pressures. The participants with HK presented a mean foot pressure that was 32.3% higher than in those with no such condition. These values can be considered predictive for the appearance of HK and should be indicative of the need for preventive treatment.

Tibialis posterior muscle stiffness assessment in flat foot subjects by ultrasound based Shear-Wave Elastography

BACKGROUND

Few methodologies are used to assess Tibialis Posterior muscle stiffness. Those present limitations leading to a lack of evidence. Muscle stiffness assessment can help in the injuries risk factors identification while coupling with Ultrasound based Shear-Wave Elastography for its management. However, a precise and reliable methodology needs to be utilized to increase stiffness accuracy among the entire Tibialis Posterior muscle. Therefore, this study aims to investigate the stiffness association between Tibialis posterior deep and superficial layer and between flat and neutral footed subjects.

METHODS

The sample consisted of 18 participants, where 9 subjects represent the flatfoot group and 9 the neutral foot group. Only the subjects who presented a Navicular Drop Test value of > 9 mm were included in the flatfooted group. All participants were submitted to the Tibialis posterior stiffness assessment with the help of Ultrasound base Shear-Wave Elastography in a lying supine position. Association between Tibialis Posterior deep and superficial layers were determined by Pearson's correlation analysis and group differences were assessed using the U-Mann Whitney test in the comparison between flat foot and neutral foot group (p < 0.05).

RESULTS

No significant correlations between Tibialis Posterior layers stiffness were found (p = 0.194), nor in the comparison between both neutral and flat foot groups (p = 0.424/p = 0.258).

CONCLUSION

Among participants, no associations between tibialis posterior layers stiffness were found. Also, we did not find any differences in the stiffness between flat and neutral foot groups. In this study, the stiffness did not differentiate flat-footed subjects from neutral subjects.

Functional gait analysis reveals insufficient hindfoot compensation for varus and valgus osteoarthritis of the knee

PURPOSE

The hindfoot is believed to compensate varus and valgus deformities of the knee by eversion and inversion movements. But these mechanisms were merely found in static radiologic measurements. The aim of this study was, therefore, to assess dynamic foot posture during gait using pressure-sensitive wireless insoles in patients with osteoarthritis of the knee and frontal knee deformities.

METHODS

Patients with osteoarthritis of the knee were prospectively included in this study. Patients were clinically and radiologically (mechanical tibiofemoral angle (mTFA), hindfoot alignment view angle (HAVA), and talar tilt (TT)) exa mined. Gait line analysis was conducted using pressure-sensitive digital shoe insoles.

RESULTS

Eighty-two patients (varus n = 52, valgus n = 30) were included in this prospective clinical study. Radiologically, the mTFA significantly correlated with the HAVA (cor = -0.72, p < 0.001) and with the TT (Pearson's cor = 0.32, p < 0.006). Gait analysis revealed that the gait lines in varus knee osteoarthritis were lateralized, despite the hindfoot valgus. In valgus knee osteoarthritis, gait lines were medialized, although the hindfoot compensated by varization.

CONCLUSIONS

Functional dynamic gait analysis could demonstrate that the hindfoot is not able to sufficiently compensate for frontal malalignments of the knee joint, contrary to static radiologic findings. This led to a narrowing of the joint space of the ankle medially in varus and laterally in valgus knee osteoarthritis.

Children's foot parameters and basic anthropometry - do arch height and midfoot width change?

The aims of this study were as follows: (1) to assess how foot posture and morphology assessments change according to body mass index (BMI) status; (2) to determine which body composition parameter (BMI or waist circumference) correlates better with the foot posture index (FPI), arch height index (AHI), and midfoot width (MFW) in children. Foot morphometry (FPI, AHI, and MFW) and body composition (BMI and waist circumference (WC)) were assessed in a cross-sectional study of 575 children (mean age = 7.42 ± 1.67 years; 53.27% female). When comparing BMI groups, an increase of 8.3% in AHI and 13.6% in MFW (both p < 0.0001) was seen. In linear regression analyses, BMI and WC were positively associated with MFW explaining together 64.8% of its variance. Noteworthy, MFW is the most related to body composition parameters.

CONCLUSION

Foot morphology assessed by FPI, AHI, and MFW differs among BMI categories in children. Noteworthy, WC correlates better with foot measures than does the more commonly used BMI, and more importantly the MFW is the foot measure best explained by children's body weight. Since foot morphometry is different among different BMI groups, children would benefit from shoes with different patterns (thinner and wider), as well as a good system to adjust midfoot height.

WHAT IS KNOWN

• Children who are overweight and obese have flatter feet, when assessed using footprints. • Up to 72% of people have incorrectly fitted shoes.

WHAT IS NEW

• Children with underweight have thinner and flatter feet than children with normal weight, while children with overweight and obesity have wider and higher arched feet. • Body weight is related to foot shape, which has relevance for footwear manufacturers.

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

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

Symptomatic and asymptomatic pronated feet show differences in the forefoot abduction motion during jogging, but not in the arch deformation

Pronated feet have been associated with higher risks of running-related overuse injuries than neutral feet. However, it remains unclear why some pronated feet develop running-related injuries, while others do not. This study aimed to examine the differences in foot kinematics during jogging among individuals with symptomatic pronated feet (SP), asymptomatic pronated feet (AP) and asymptomatic neutral feet (AN). Thirty-nine recreational runners were recruited and classified into the SP, AP and AN groups. Statistical parametric mapping (SPM) and ANOVA were used to identify kinematic differences among three groups. The SPM results showed that the SP had larger forefoot abduction than the AN and AP during jogging, while three groups had similar rearfoot eversion during jogging. Both the AP and SP had larger forefoot sagittal range of motion (ROM) (mean difference = 3.5 and 4.8 deg, respectively) and smaller rearfoot sagittal ROM (mean difference = 5.0 and 3.5 deg, respectively) than the AN. Forefoot abduction during jogging may have the potential to identify pronated feet at greater risk of injury. Pronated feet, symptomatic or not, have comparable large forefoot sagittal ROM, i.e., arch deformation, compared to neutral feet. The findings could have implications for the injury aetiology and intervention strategies for SP.

Do different foot types affect the 6-min walk test capacity of younths with Charcot-Marie-Tooth neuropathy ?

BACKGROUND

The present study aimed to assess the gait capacity of youths with Charcot Marie Tooth disease (CMT), considering the different foot postures as a grouping variable.  METHODS: The total distance, the predicted distance, and gait velocity obtained during the six-minute walking test (6MWT) were compared between participants with and without CMT. In addition, part of the CMT group completed a 12-month follow-up. The study evaluated 63 participants (CMT group = 31; Non-CMT group = 32) aged 6 to 18, both sexes. Data included anthropometric measures, foot posture index (FPI), the distance (D6), percentage of predicted distance (%D6), and walking velocity(V) in 6MWT.

RESULTS

The D6% presented no significant difference between the types of feet in CMT or Non-CMT (p < 0.05, Kruskal Wallis test). CMT presented reduced values of D6, %D6, and V when compared to Non-CMT.

CONCLUSIONS

These findings indicate that gait performance was decreased in youths with CMT in comparison to non-CMT. Contrary to what was expected, the cavus foot type did not show lower gait capacity than the flatfoot, suggesting that the types of feet alone did not determine differences in gait capacity within the CMT group.

Is there a relationship between lower-extremity injuries and foot postures in professional football players? A prospective cohort study

BACKGROUND

Lower extremity injuries are an ongoing concern for professional football players. This study aims to evaluate the relationship between foot posture and lower extremity injuries in professional football players.

METHOD

In this prospective cohort study, 420 male players of the Iran Premium football league were evaluated during the 2015-2016 season. The players were assessed for their foot types based on optical and static foot scans and foot posture index (FPI). The trained club physicians recorded all injuries during the season.

RESULT

The analyzed data of 244 players showed the highest rate of lower extremity injury in hamstrings, ankle, and groin, respectively. These injuries led to 46% of time loss. The probability of hamstrings injuries was higher among pronated players based on static, optic, FPI, and visual examination, 2.1, 1.8, 1.8, and 2.3, respectively. Medial Collateral Ligament (MCL) injuries were associated with subtalar joint abnormality defined by visual observation. An increased relative risk of leading-to-absence injuries among the flat foot group was significant based on optic scanning, FPI, and visual observation.

CONCLUSION

Abnormal foot postures in professional football players may increase the risk of hamstring and MCL injuries and time loss due to lower extremity injuries.

Dose-response effects of forefoot and arch orthotic components on the center of pressure trajectory during running in pronated feet

BACKGROUND

Foot orthoses are widely used in runners with pronated feet, who are characterized with large forefoot abduction and arch deformation during gait. However, the relationship between the amount of forefoot and arch orthotic correction and the alterations in foot biomechanics remains unclear.

RESEARCH QUESTION

This study aimed to determine dose-response effects of foot orthoses with forefoot wedge and arch support components on the center of pressure (COP) trajectories and pressure distribution during running in symptomatic pronated feet.

METHODS

Fifteen recreational runners participated in this study. A pressure plate was used to measure plantar pressures during running with control shoe only and ten foot orthoses, varying in forefoot wedges (5 levels) and arch supports (2 levels). The COP trajectory across the entire stance phase was compared between orthotic and control conditions using one-dimensional statistical parametric mapping. The differences in the force-time integral (FTI) and temporal variables were explored between conditions using repeated measures ANOVAs. The main effect of the two orthotic components and their interaction on tested variables were examined using two-way ANOVAs.

RESULTS

A forefoot wedge, whether laterally or medially located, shifted the COP trajectory laterally during some subphases of running (p < 0.05), while using an arch support only had minimal effect on the COP. Almost all orthoses reduced the FTI on the 2nd metatarsal and medial heel, and only medial forefoot wedges reduced the FTI on the hallux. There was a linear effect of forefoot wedges on the medial-lateral COP displacements during the propulsion phase, but no interactions were found between two orthotic components.

SIGNIFICANCE

These findings suggest that forefoot orthotic components rather than arch supports are effective in altering forefoot dynamics in runners with pronated feet. This study could have implications for foot orthotic prescription and running-related injury prevention for individuals with pronated feet.

Assessment of foot posture and related factors in patients with knee osteoarthritis

Objectives

The aim of this study was to compare foot posture between patient and control groups, and to identify factors associated with foot posture abnormality in knee osteoarthritis (OA).

Patients and methods

This case-control study included a total of 115 patients (26 males, 89 females; mean age: 54.4±9.3 years; range, 29 to 73 years) with OA and 77 healthy controls (20 males, 57 females; mean age: 52.1±8.1 years; range, 32 to 69 years) between May 2019 and July 2019. The participants were evaluated using the Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC), Visual Analog Scale (VAS), and the Beighton criteria. Radiological assessments were performed using the Kellgren-Lawrence grading, condylar plateau angle, and medial tibiofemoral joint width. The Foot Posture Index-6 (FPI-6) was used for foot posture analysis and three groups were formed as supinated, neutral, and pronated postures.

Results

Foot posture was significantly different between the patient and control groups (p<0.05). Of the patients with knee OA, significant differences were found in the VAS, WOMAC-pain, WOMAC-physical function, and WOMAC-total (p<0.05) among the foot postures. No significant difference was found among the foot posture groups in terms of the radiological parameters and WOMAC-stiffness (p>0.05). Hypermobility and WOMAC-total scores were significantly associated with foot posture abnormality (p<0.05).

Conclusion

Joint hypermobility and foot posture are the factors which may influence the clinical characteristics of knee OA. Foot posture and joint hypermobility should be taken into consideration during the examination and management of patients with knee OA.

Abnormalities of foot and ankle alignment in individuals with chronic ankle instability: a systematic review

Background

To prevent recurrent ankle sprain, it is important to clarify the pathology of chronic ankle instability (CAI). An association has been reported between CAI and abnormalities of foot posture and ankle alignment. There is no consensus on the types of these abnormalities that occur in individuals with CAI. The objective of this systematic review is to clarify the relevance of abnormality of foot posture and ankle alignment for CAI.

Methods

A systematic computerized literature search was performed of the PubMed, CINAHL, SPORTDiscus, Web of Science, and the Cochrane Register of Clinical Trials databases. The selected studies either compared CAI patients with a control group or CAI ankles with contralateral healthy ankles and specifically reported foot posture and alignment of the ankle in the outcomes. They were written in English and published prior to June 2021. The methodological quality of the included studies was evaluated using a 16-question index. Data were extracted independently by two reviewers, and the certainty of evidence was assessed using GRADE approach.

Results

Sixteen studies including 872 patients of high to low methodological quality were included. These showed there was significant anterior displacement and internal rotation of the talus in CAI ankles (low evidence), but there was no consensus on fibular alignment or foot posture.

Conclusions

This review showed there was significant anterior displacement and internal rotation of the talus in CAI ankles but found no consensus on the characteristics of fibular and foot alignment. Further investigations are required to clarify the characteristic foot and ankle malalignment in CAI to facilitate the development of efficient interventions.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12891-021-04537-6.

Alligators employ intermetatarsal reconfiguration to modulate plantigrade ground contact

Feet must mediate substrate interactions across an animal's entire range of limb poses used in life. Metatarsals, the ‘bones of the sole’, are the dominant pedal skeletal elements for most tetrapods. In plantigrade species that walk on the entirety of their sole, such as living crocodylians, intermetatarsal mobility offers the potential for a continuum of reconfiguration within the foot itself. Alligator hindlimbs are capable of postural extremes from a belly sprawl to a high walk to sharp turns – how does the foot morphology dynamically accommodate these diverse demands? We implemented a hybrid combination of marker-based and markerless X-ray reconstruction of moving morphology (XROMM) to measure 3D metatarsal kinematics in three juvenile American alligators (Alligator mississippiensis) across their locomotor and maneuvering repertoire on a motorized treadmill and flat-surfaced arena. We found that alligators adaptively conformed their metatarsals to the ground, maintaining plantigrade contact throughout a spectrum of limb placements with non-planar feet. Deformation of the metatarsus as a whole occurred through variable abduction (twofold range of spread) and differential metatarsal pitching (45 deg arc of skew). Internally, metatarsals also underwent up to 65 deg of long-axis rotation. Such reorientation, which correlated with skew, was constrained by the overlapping arrangement of the obliquely expanded metatarsal bases. Such a proximally overlapping metatarsal morphology is shared by fossil archosaurs and archosaur relatives. In these extinct taxa, we suggest that intermetatarsal mobility likely played a significant role in maintaining ground contact across plantigrade postural extremes.

Summary: We measured 3D metatarsal kinematics in American alligators. Alligator metatarsals conform with the ground across a diversity of high walk and maneuvering postures, providing a context for interpreting the evolutionary history of metatarsals in the fossil record.

Comparison Of Short-Term Effects Of Virtual Reality and Short Foot Exercises In Pes Planus

BACKGROUND

Virtual reality exercises (VRE) offers functional, multipurpose usage with a motivational approach. This study aimed to compare VRE and short foot exercises (SFE) in individuals with flexible pes planus.

METHODS

Forty participants with pes planus were assigned to the SFE group (n = 20) or VR exercise group (n = 20). Both groups performed exercises three times a week for four weeks. The groups were assessed with a navicular drop test for the height of the medial longitudinal arch, craig Test for femoral anteversion, Star Excursion Test for balance,10 step test for performance.

RESULTS

For two groups there is a statistically significant difference between before and after treatments(p < 0.05). There is no difference between VRE and SFE groups after treatments for all parameters(p > 0.05).

CONCLUSIONS

Two different 4-week-exercise programs for pes planus have a similar effect on performance, balance, and navicular drop values in both groups. It was considered that the practice of VR exercises like short foot exercises could also address rehabilitation goals, which included improving balance, performance, and foot posture. CLINICALTRIALS.

GOV IDENTIFIER

NCT04283357.

Foot characteristics and mechanics in individuals with knee osteoarthritis: systematic review and meta-analysis

Background

Foot characteristics and mechanics are hypothesized to affect aetiology of several lower extremity musculoskeletal conditions, including knee osteoarthritis (KOA). The purpose of this systematic review was to identify the foot characteristics and mechanics of individuals with KOA.

Methods

Five databases were searched to identify relevant studies on foot characteristics and mechanics in people with KOA. Meta-analyses were performed where common measures were found across included studies. Included studies were evaluated for data reporting quality using the STROBE (STrengthening the Reporting of OBservational studies in Epidemiology) checklist.

Results

Thirty-nine studies were included in this systematic review. Two studies reported participants with KOA had statistically significantly (P < 0.05) more pronated foot postures than those without. Meta-analyses for foot progression angle (FPA) and peak rearfoot eversion angle found no difference between those with and without KOA (FPA mean difference:-1.50 [95% confidence interval − 4.20-1.21]; peak rearfoot eversion mean difference: 0.71 [1.55–2.97]).

Conclusion

A more pronated foot posture was noticed in those with KOA. However, it was not possible to establish a relationship between other foot characteristics or mechanics in people with KOA due to heterogeneity between the included study and limited number of studies with similar measurements. There is need for identifying common measurement techniques and reporting metrics when studying the foot in those with KOA.

Shank and rearfoot coordination and its variability during running in flatfoot

Flatfoot is a risk factor for patellofemoral pain syndrome (PFPS), and excessive rearfoot eversion occurring in flatfoot has been associated with the development and progression of PFPS; however, the mechanism remains unclear. This study aimed to investigate transverse shank and frontal rearfoot coordination patterns and variability when running with normal foot and flatfoot. Participants with normal foot (n = 13) and flatfoot (n = 13) were asked to run at their preferred speed. The coupling angle between the shank and rearfoot, representing intersegmental coordination, was calculated using the modified vector coding technique and categorized into four coordination patterns. Standard deviation of the coupling angle was computed as a measure of coordination variability during the stance phase. No differences in the characteristics and spatiotemporal parameters between groups were found, and all participants had rearfoot strike pattern. During midstance, the flatfoot group showed a significantly greater proportion of anti-phase with proximal (shank) dominancy than the normal foot group (p = 0.04, effect size = 0.88 [large]). Furthermore, flatfoot group showed a significantly greater in variability than the normal foot group (p = 0.03, effect size = 0.91 [large]). This study's results may help explain why flatfoot is likely to result in PFPS. However, the occurrence mechanism of running injuries like PFPS is multi- factorial. Since these results alone are not sufficient to explain the cause-effect relationship between flatfoot and injuries like PFPS, a prospective study including other factors such as patellofemoral joint stress would also be needed.

Influence of foot posture on immediate biomechanical responses during walking to variable-stiffness supported lateral wedge insole designs

BACKGROUND

Novel designs of lateral wedge insoles with arch support can alter walking biomechanics as a conservative treatment option for knee osteoarthritis. However, variations in foot posture may influence individual responses to insole intervention and these effects are not yet known.

RESEARCH QUESTION

How does foot posture influence biomechanical responses to novel designs of lateral wedge insoles with arch support?

METHODS

This exploratory biomechanical investigation categorized forty healthy volunteers (age 23-34) into pronated (n = 16), neutral (n = 15), and supinated (n = 9) foot posture groups based on the Foot Posture Index. Three-dimensional gait analysis was conducted during walking with six orthotic insole conditions: flat control, lateral wedge, uniform-stiffness arch support, variable-stiffness arch support, and lateral wedge + each arch support. Frontal plane knee and ankle/subtalar joint kinetic and kinematic outcomes were compared among insole conditions and foot posture groups using a repeated measures analysis of variance.

RESULTS

The lateral wedge alone and lateral wedge + variable-stiffness arch support were the only insole conditions effective at reducing the knee adduction moment. However, the lateral wedge + variable-stiffness arch support had a smaller increase in peak ankle/subtalar eversion moment than the lateral wedge alone. Supinated feet had smaller ankle/subtalar eversion excursion and moment impulse than neutral and pronated feet, across all insole conditions.

SIGNIFICANCE

Supinated feet have less mobile ankle/subtalar joints than neutral and pronated feet and, as a result, may be less likely to respond to biomechanical intervention from orthotic insoles. Supported lateral wedge insoles incorporating an arch support design that is variable-stiffness may be better than uniform-stiffness since reductions in the knee adduction moment can be achieved while minimizing increases in the ankle/subtalar eversion moment.

Posture of the foot: Don't keep it out of sight, out of mind in knee osteoarthritis

BACKGROUND

There are many contributors of knee osteoarthritis including the postural abnormalities of the adjacent joints. The relationship between foot posture and the clinical-radiological parameters of knee osteoarthritis is poorly understood.

RESEARCH QUESTION

Is foot posture related to the clinical and radiological parameters in patients with knee osteoarthritis?

METHODS

Patients diagnosed with primary clinical and radiographic medial tibiofemoral knee osteoarthritis were included in the study. Anteroposterior knee radiographs were staged by using the Kellgren-Lawrence grading system. Computer-based measurements of the medial joint space width (mJSW), condylar angle, anatomical axis angle, tibial plateau angle and condylar plateau angle were performed on digital anteroposterior knee radiographs. The Western Ontario and Mc Master University Osteoarthritis Index (WOMAC) questionnaire was used to assess pain and the functional status of the patients. Foot posture was assessed by the Foot Posture Index (FPI) system and feet were categorized into three (pronated, neutral and supinated).

RESULTS

The study included 150 patients (150 knees and feet at one side) with a mean age of 61.2 ± 10.1 years. In terms of foot posture groups; percentages for supination, neutral and pronation were 22.66%, 68.66% and 8.66%, respectively. In the group with supinated FPI; WOMAC total score, pain and function subscale scores were higher (p < 0.001), mJSW was narrowed (p = 0.038) and the condylar plateau angle was increased (p = 0.009). In the FPI pronation group; anatomic axis angle values were found to change in the varus direction (p = 0.012).

SIGNIFICANCE

The potential postural dysfunction of the foot should be taken into consideration during the assessment and/or management of a patient with knee osteoarthritis.

Reliability of Foot Posture Index individual and total scores for adults and older adults

BACKGROUND

Previous studies have suggested that the Foot Posture Index (FPI-6) is valid and reliable to evaluate foot posture of adults and children. However, studies with adults had some important limitations. In addition, it is not clear if FPI-6 is reliable for older adults. Variations in foot structure, such as edema, bone callosity and bunions, are more frequent in older adults, which may compromise FPI-6 reliability for this population.

OBJECTIVES

To investigate test-retest and inter-rater reliability of FPI-6 total and individual scores for the assessment of foot posture of adults and older adults.

METHODS

Twenty-one adults and 19 older adults participated in this study. The examiners performed FPI-6 on two days of data collection. We used Cohen Weighted Kappa and Intraclass Correlation Coefficient for categorical and continuous variables, respectively.

RESULTS

For adults, FPI-6 scores demonstrated test-retest reliability varying from fair to substantial and inter-rater reliability varying from fair to almost perfect. For older adults, FPI-6 scores demonstrated test-retest reliability varying from not reliable to moderate and inter-rater reliability varying from fair to almost perfect. The examiners demonstrated more than 80% of agreement in all FPI-6 scores for adults and older adults.

CONCLUSIONS

The relatively low reliability in light of this high level of agreement suggest that the current version of FPI-6 can be a useful tool to assess foot posture for adults and should be further examined. On the other hand, FPI-6 should be cautiously used for older adults.

Paediatric flexible flat foot: how are we measuring it and are we getting it right? A systematic review

BACKGROUND

Flexible flat foot is a normal observation in typically developing children, however, some children with flat feet present with pain and impaired lower limb function. The challenge for health professionals is to identify when foot posture is outside of expected findings and may warrant intervention. Diagnoses of flexible flat foot is often based on radiographic or clinical measures, yet the validity and reliability of these measures for a paediatric population is not clearly understood. The aim of this systematic review was to investigate how paediatric foot posture is defined and measured within the literature, and if the psychometric properties of these measures support any given diagnoses.

METHODS

Electronic databases (MEDLINE, CINAHL, EMBASE, Cochrane, AMED, SportDiscus, PsycINFO, and Web of Science) were systematically searched in January 2017 for empirical studies where participants had diagnosed flexible flat foot and were aged 18 years or younger. Outcomes of interest were the foot posture measures and definitions used. Further articles were sought where cited in relation to the psychometric properties of the measures used.

RESULTS

Of the 1101 unique records identified by the searches, 27 studies met the inclusion criteria involving 20 foot posture measures and 40 definitions of paediatric flexible flat foot. A further 18 citations were sought in relation to the psychometric properties of these measures. Three measures were deemed valid and reliable, the FPI-6 > + 6 for children aged three to 15 years, a Staheli arch index of > 1.07 for children aged three to six and ≥ 1.28 for children six to nine, and a Chippaux-Smirak index of > 62.7% in three to seven year olds, > 59% in six to nine year olds and ≥ 40% for children aged nine to 16 years. No further measures were found to be valid for the paediatric population.

CONCLUSION

No universally accepted criteria for diagnosing paediatric flat foot was found within existing literature, and psychometric data for foot posture measures and definitions used was limited. The outcomes of this review indicate that the FPI - 6, Staheli arch index or Chippaux-Smirak index should be the preferred method of paediatric foot posture measurement in future research.

Correlates and predictors of paediatric leg pain: a case-control study

Paediatric leg pains, long described as 'growing pains', frequently present to clinicians, are prevalent in early childhood, disrupt sleep, and distress affected children and parents. There are many cited associations, but no defined leg pain sub-types, nor revealed predictive factors. We explored the implicated factors (viz. foot arches, foot strength, joint mobility, vitamin D, iron) in children with leg pain versus a control group. Leg pain sub-groups-growing pains (GP), restless legs (RLS), both (mixed)-are defined for the first time. A case controlled study design, in a primary care setting, Mumbai, India. A total of 77 children with leg pains (n = 64) and controls (n = 13), aged 3-12 years, identified by paediatricians, completed data collection. Blood assays for iron and vitamin D, pain, Beighton score, foot arch, foot strength and anthropometrical data were collected. All outcome measures were validated, with standardised protocols. Leg pain (all groups) was predicted by increased joint mobility and increased ankle dorsiflexion strength (β = 0.56, P < 0.05). GP sub-group was predicted by increased ankle dorsiflexion strength (β = - 0.06, P < 0.05). Mixed (GP/RLS) and RLS sub-groups were predicted by increased ankle dorsiflexion strength (β = 0.66, P < 0.05) and pain questionnaire (β = 0.11, P < 0.05). Hypovitaminosis D was detected in 87% of the sample, and anaemia in 13%. Increased strength of ankle dorsiflexors and joint flexibility were each found predictive for leg pain. Increased body weight, waist girth, and BMI were all associated with leg pain.

The relationship between foot posture and plantar pressure during walking in adults: A systematic review

BACKGROUND

Foot posture is a risk factor for some lower limb injuries, however the underlying mechanism is not well understood. Plantar pressure analysis is one technique to investigate the interaction between foot posture and biomechanical function of the lower limb.

RESEARCH QUESTION

The aim of this review was to investigate the relationship between foot posture and plantar pressure during walking.

METHODS

A systematic database search was conducted using MEDLINE, CINAHL, SPORTDiscus and Embase to identify studies that have assessed the relationship between foot posture and plantar pressure during walking. Included studies were assessed for methodological quality. Meta-analysis was not conducted due to heterogeneity between studies. Inconsistencies included foot posture classification techniques, gait analysis protocols, selection of plantar pressure parameters and statistical analysis approaches.

RESULTS

Of the 4213 citations identified for title and abstract review, sixteen studies were included and underwent quality assessment; all were of moderate methodological quality. There was some evidence that planus feet display higher peak pressure, pressure-time integral, maximum force, force-time integral and contact area predominantly in the medial arch, central forefoot and hallux, while these variables are lower in the lateral and medial forefoot. In contrast, cavus feet display higher peak pressure and pressure-time integral in the heel and lateral forefoot, while pressure-time integral, maximum force, force-time integral and contact area are lower for the midfoot and hallux. Centre of pressure was more laterally deviated in cavus feet and more medially deviated in planus feet. Overall, effect sizes were moderate, but regression models could only explain a small amount of variance in plantar pressure variables.

SIGNIFICANCE

Despite these significant findings, future research would benefit from greater methodological rigour, particularly in relation to the use of valid foot posture measurement techniques, gait analysis protocols, and standardised approaches for analysis and reporting of plantar pressure variables.

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

BACKGROUND

Variations 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.

METHODS

Ninety-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.

RESULTS

Overall, 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.

Structural differences in the lower extremities in children aged 7-9 years, caused by playing football: A cross-sectional study

BACKGROUND

Physical activity during childhood can be beneficial in the long term. However, this practice can influence the child's physiological development. The aim of this study was to determine whether the practice of soccer, in moderation, could be a risk factor for the inadequate development of the lower limb.

METHODS

The study group was composed of 115 children, of whom 59 (mean age 8.03±0.89years) practised soccer 3 times a week and had a positive Physical Activity Questionnaire for Adolescents (PAQ-A) score, while a further 56 (mean age 7.96±0.87years) did not perform any additional physical activity and had a negative PAQ-A score. A foot posture analysis, based on the foot posture index (FPI), the valgus index, the orientation of the subtalar joint (STJ) and the Q angle of the knee, was carried out.

RESULTS

For the group of soccer players, the following results were obtained: FPI 4.79±2.38 (R) and 3.95±2.31 (L); valgus index 13.56°±1.66° (R) and 13.42°±1.48° (L); STJ test 79% pronated; Q angle 13.13°±2.06° (R) and 13.18°±1.93° (L). For the non-players, the corresponding values were: FPI 3.62±2.82 (R) and 3.74±2.77 (L); valgus index 12.76°±1.71° (R) and 12.84°±1.72° (L); STJ test 50% pronated; Q angle 13.87°±3.01° (R) and 13.86°±2.94° (L).

CONCLUSION

There is a degree of difference between the two groups, but the values do not vary greatly from those considered normal for this age group. Any alterations in this respect can be assumed to be caused at older ages than those analysed.

Centre of pressure characteristics in normal, planus and cavus feet

Background

The 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.

Methods

Ninety-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.

Results

The 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.

Conclusion

These 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.

The typically developing paediatric foot: how flat should it be? A systematic review

Background

All typically developing children are born with flexible flat feet, progressively developing a medial longitudinal arch during the first decade of their lives. Whilst the child’s foot is expected to be flat, there is currently no consensus as to how flat this foot should be. Furthermore, whilst feet are observed to decrease in flatness with increasing age, it is not known how flat they should be at each age increment. The objective of this systematic review is to define the postural characteristics of the ‘typically’ developing paediatric foot.

Methods

The PRISMA protocol was applied to compare all data currently published describing the typical development of the paediatric foot. The Epidemiological Appraisal Instrument (EAI) was used to assess the risk of bias of the included studies.

Results

Thirty four epidemiological papers pertaining to the development of the paediatric foot were graphically compared. Sixteen different foot posture assessments were identified of which footprint based measures were the most reported outcome.

Conclusion

Firstly, the use of the term normal in relation to foot posture is misleading in the categorisation of the paediatric foot, as indeed a flat foot posture is a normal finding at specific ages. Secondly, the foot posture of the developing child is indeed age dependent and has been shown to change over time. Thirdly, no firm conclusion could be reached as to which age the foot posture of children ceases to develop further, as no two foot measures are comparable, therefore future research needs to consider the development of consensus recommendations as to the measurement of the paediatric foot, using valid and reliable assessment tools.

Electronic supplementary material

The online version of this article (doi:10.1186/s13047-017-0218-1) contains supplementary material, which is available to authorized users.

Association of frontal plane knee alignment with foot posture in patients with medial knee osteoarthritis

Background

To examine the association of radiographic frontal plane knee alignment with three-dimensional foot posture in patients with medial knee osteoarthritis (OA).

Methods

Participants in orthopedic clinics with Kellgren/Lawrence (K/L) grade ≥1 (88 patients and 88 knees; age, 61–91 years; 65.9% female) were enrolled. An anteroposterior radiographic view was used to assess the anatomical axis angle (AAA) after subtracting a sex-specific correction factor. The three-dimensional foot posture was also evaluated.

Results

Multiple regression analyses showed that increased corrected AAA (i.e., valgus direction) was independently associated with a decrease in the hallux valgus angle (regression coefficient: −0.40 per degree, 95% confidence interval [CI]: −0.72, −0.09; P = 0.013) and increase in the pronation angle of the calcaneus relative to floor (regression coefficient: 0.33 per degree, 95% CI: 0.10, 0.56; P = 0.005) adjusted for age, sex, and body mass index. The relationship between the corrected AAA and hallux valgus angle strengthened (regression coefficient: −0.60 per degree, 95% CI: −1.08, −0.13; P = 0.014) in varus-aligned knees examined separately (63 knees). The other foot postures (navicular height, navicular height/foot length, and rearfoot angle) were not significantly associated with corrected AAA.

Conclusions

Radiographic frontal plane knee alignment was associated with hallux valgus angle and calcaneus angle relative to the floor in patients with medial knee OA, particularly in varus-aligned knees. These results indicate a connection between altered frontal knee alignment and foot posture, which may be helpful in understanding the pathogenesis of altered foot posture observed in patients with knee OA.

Influence of foot posture on the functioning of the windlass mechanism

The absence of a functioning windlass mechanism may delay re-supination of the foot during locomotion and put excess stress on the mid-tarsal joint and soft tissues of the foot. The purpose of this study was to describe the foot posture of individuals that have an impaired or absent windlass mechanism. Forty-seven individuals (34 females and 13 males) with a mean age of 26 years were recruited to participate in this study. The Foot Posture Index was used to visually assess the posture of both feet. In addition, a digital gauge was used to measure dorsal arch height and midfoot width in bilateral resting standing. Dorsal arch height and mid-foot width were also measured in non-weight bearing. Finally, for those individuals without a functioning windlass mechanism, the amount of medial wedging needed to restore its function was measured. Subjects with an "absent" or "impaired" windlass mechanism had a mean Foot Posture Index of +6.8 (sd=2.5) compared to +2.5 (sd=3.1) for those with a functioning windlass mechanism. A series of independent t-tests showed that individuals without a functioning windlass mechanism had a more pronated foot posture, a lower dorsal arch height and a wider mid-foot width compared to those that had a functioning windlass mechanism. Finally, an average medial wedge of 5.1mm (sd=2.1) was able to produce a functioning windlass mechanism in those individuals that previously lacked one.

The influence of foot posture on dorsiflexion range of motion and postural control in those with chronic ankle instability

BACKGROUND

To investigate the effect of foot posture on postural control and dorsiflexion range of motion in individuals with chronic ankle instability.

METHODS

The study employed a cross-sectional, single-blinded design. Twenty-one individuals with self-reported chronic ankle instability (male=5; age=23.76(4.18)years; height=169.27(11.46)cm; weight=73.65(13.37)kg; number of past ankle sprains=4.71(4.10); episode of giving way=17.00(18.20); Cumberland Ankle Instability Score=18.24(4.52); Ankle Instability Index=5.86(1.39)) participated. The foot posture index was used to categorize subjects into pronated (n=8; Foot Posture Index=7.50(0.93)) and neutral (n=13; Foot Posture Index=3.08(1.93)) groups. The dependent variables of dorsiflexion ROM and dynamic and static postural control were collected for both groups at a single session.

FINDINGS

There were no significant differences in dorsiflexion range of motion between groups (p=0.22) or any of the eyes open time-to-boundary variables (p>0.13). The pronated group had significantly less dynamic postural control than the neutral group as assessed by the anterior direction of the Star Excursion Balance Test (p<0.04). However, the pronated group had significantly higher time-to-boundary values than the neutral group for all eyes closed time-to-boundary variables (p≤0.05), which indicates better eyes closed static postural control.

INTERPRETATION

Foot posture had a significant effect on dynamic postural control and eyes closed static postural control in individuals with chronic ankle instability. These findings suggest that foot posture may influence postural control in those with chronic ankle instability.

The use of a static measure to predict foot posture at midstance during walking

Previous studies have successfully used the longitudinal arch angle (LAA) to assess foot posture, but the measurement consistency and ability of the LAA to predict dynamic foot posture during activity in a variety of foot types have not been evaluated. The purpose of this study was to determine the reliability of the LAA as well as if the clinical method of assessing the LAA could be used to predict the LAA at midstance during walking for supinated, normal, and pronated foot types. The Arch Height Ratio was used to select 35 participants with 12 supinated, 46 normal, and 12 pronated feet. A standard goniometer was used to measure the LAA (CLINIC_LAA) on both feet while standing. Both feet were then filmed using a high speed camera while walking on a treadmill. The LAA was determined by the angle formed by two lines drawn between the markers placed on the first metatatarsal and medial malleolus with the apex the navicular tuberosity. The LAA in midstance (WALK_LAA) was determined using the mean of five walking trials. The reliability of the CLINIC_LAA assessed on both feet by two raters over two days were excellent. There was no difference between the left and right foot for the CLINIC_LAA. The Pearson correlation between CLINIC_LAA and WALK_LAA for all 70 feet was r=0.96 (r²=0.92). The results indicate the LAA is highly predictive of foot posture at midstance in walking explaining over 90% of the variance for a wide range of foot types.

Effects of body mass index on foot posture alignment and core stability in a healthy adult population

Foot biomechanics and core stability (CS) play significant roles in the quality of standing and walking. Minor alterations in body composition may influence base support or CS strategies. The aim of this study was to investigate the effect of the body mass index (BMI) on the foot posture index (FPI) and CS in a healthy adult population. A total of 39 healthy adult subjects with a mean age of 24.3±6.4 years and over-weight BMI values between 25 and 29.9 kg/m2 (27.43±6.1 kg/m2) participated in this study. Foot biomechanics were analyzed using the FPI. CS was assessed using a plank test with a time-to-failure trial. The Spearman correlation coefficient indicated a significant correlation between BMI and both the FPI (r=0.504, P=0.001) and CS (r= -0.34, P=0.036). Present study concluded that an overweight BMI influences foot posture alignment and body stability. Consequently, BMI should be considered during rehabilitation management for lower extremity injuries and body balance.

The relationship between foot posture, body mass, age and ankle, lower-limb and whole-body flexibility in healthy children aged 7 to 15 years

Background

The complex relationship between foot posture, flexibility, body mass and age in children is not well understood. The objectives of this post hoc analysis were to explore the relationships between foot posture, flexibility, body mass in children aged seven to 15 years.

Methods

Thirty healthy, asymptomatic children (20 girls, 10 boys) aged 7 to 15 years with a mean age (SD) of 10.7 (2.3) years, were recruited through the Auckland University of Technology (AUT) Podiatry Clinic, Auckland, New Zealand. Clinical data were collected by a podiatrist with 20 years’ experience and included: height and weight (for Body Mass Index), Foot Posture Index-6 (FPI), Beighton score, Lower Limb Assessment Scale score (LLAS); and ankle lunge angle. For this post hoc analysis, Pearson’s test and Spearman’s rho were used to explore relationships between variables. Statistical significance level was p < 0.05.

Results

Data for each of the 30 participants for each variable were included in analyses, which returned the following statistically significant results: higher FPI was associated moderately with higher Beighton score (r = 0.44, p = 0.01); greater lunge angle was associated moderately with higher Beighton (r = 0.40, p = 0.02) and LLAS (r = 0.42, p = 0.02) scores; older age was associated strongly with higher BMI (r = 0.52, p = <0.01) and moderately with lower Beighton (r = −0.41, p = 0.024) and LLAS (r = −0.40, p = 0.03) scores; and higher Beighton score was associated strongly with higher LLAS (r = 0.85, p = <0.01). There was no difference in foot posture between girls and boys (p = 0.21).

Conclusions

In this sample of healthy, asymptomatic children age 7 to 15 years, children with a more pronated foot type exhibited greater lower limb and whole-body flexibility, but not greater ankle joint flexibility. There was strong agreement between lower-limb and whole-body flexibility. This study highlights the importance of assessing the paediatric flat foot in the context of a developing body.

Range of motion, muscle length, and balance performance in older adults with normal, pronated, and supinated feet

[Purpose] To compare the lower limb joint range of motion and muscle length between different types of foot posture, and determine the correlation of range of motion and muscle length with balance performance. [Subjects and Methods] Ninety individuals (age, 65.2±4.6 years) were assessed using the Foot Posture Index to determine their type of foot (Normal [0 to +5], pronated [+6 to +9], and supinated [-1 to -4]; n=30 per group). The range of motion (goniometer), muscle length (goniometer and tape measure), and balance performance (functional reach test and four square step test) were measured for each participant. Data were analyzed using the Kruskal-Wallis test and Spearman's rank-order correlation. [Results] No significant differences were found in range of motion, muscle length, and balance performance among different types of foot posture, except for right and left ankle dorsiflexion range of motion. Balance performance was significantly correlated with selected muscle length and range of motion, especially in the supinated foot. [Conclusion] Range of motion and muscle length of the lower limb may be associated with balance performance in older adults with foot deformities. These findings may guide physiotherapists in choosing intervention based on specific assessments for older adults with foot deformity.

Navicular bone position determined by positional MRI: a reproducibility study

OBJECTIVE

To examine intraobserver, interobserver and between-day reproducibility of positional MRI for evaluation of navicular bone height (NVH) and medial navicular position (MNP).

MATERIALS AND METHODS

Positional MRI (pMRI) of the foot was performed on ten healthy participants (0.25 T G-scanner). Scanning was performed in supine and standing position, respectively. Two radiologists evaluated the images in a blinded manner. Reliability and agreement were assessed by calculation of intraclass correlation coefficient (ICC) and 95 % limits of agreement as a percentage of the mean (LOA%).

RESULTS

Intraobserver and interobserver reliability was "substantial" in both supine and standing position (ICC 0.86-0.98) and showed good agreement (LOA% 4.9-14.7 %). Between-day reliability of navicular height and medial navicular position in standing position remained substantial (ICC 0.85-0.92) with adequate agreement (LOA% 8.3-19.8 %). In supine position between-day reliability was "moderate" for NVH (ICC 0.72) and "slight" for MNP (ICC 0.39). Agreement remained adequate between-days for MNP in supine position (LOA% 17.7 %), but it was less than adequate for NVH in supine position (LOA% 24.2 %).

CONCLUSION

Navicular height and medial navicular position can be measured by pMRI in a very reproducible manner within and between observers. Increased measurement variation is observed between-days in supine position, which may be due to small positional differences or other unknown biomechanical factors.

THE USE OF A STATIC MEASURE TO PREDICT FOOT POSTURE AT MIDSUPPORT DURING RUNNING

BACKGROUND

The posture of the foot has been implicated as a factor in the development of running-related injuries. A static measure of foot posture, such as the longitudinal arch angle (LAA), that can be easily performed and is predictive of the posture of the foot at midsupport while running could provide valuable information to enhance the clinician's overall evaluation of the runner.

PURPOSE

The purpose of this study was to determine if the LAA, assessed in relaxed standing, could predict the posture of the foot at midsupport while running on a treadmill.

STUDY DESIGN

Cross-sectional Study.

METHODS

Forty experienced runners (mean age 26.6 years) voluntarily consented to participate. Inclusion criteria included running at least 18 miles per week, previous experience running on a treadmill, no history of lower extremity congenital or traumatic deformity, or acute injury three months prior to the start of the study. Each runner had markers placed on the medial malleolus, navicular tuberosity, and medial aspect 1(st) metatarsal head of both feet. A high speed camera (240 Hz) was used to film both feet of each runner in standing and while running on a treadmill at their preferred speed. The LAA in standing and at mid-support while running was determined by angle formed by two lines drawn between the three markers with the navicular tuberosity serving as the apex. The LAA in midsupport was determined using the mean of the middle five running trials.

RESULTS

The levels of intra-rater and inter-rater reliability for the dynamic LAA were excellent. The results of the t-tests indicated that mean values between the left and right foot were not significantly different for the standing or running LAA. The results of the t-tests between male and female runners were also not significantly different for standing or running LAA. The Pearson correlation between standing and running LAA for all 80 feet was r = 0.95 (r(2) = 0.90).

CONCLUSIONS

The standing LAA was found to be highly predictive of the running LAA at midsupport while running. Approximately 90% of the variance associated with foot posture at midsupport in running could be explained by the standing LAA.

LEVEL OF EVIDENCE

4, Controlled laboratory study.

Effects of different heel angles in sleep mode on heel interface pressure in the elderly

BACKGROUND

The heels are one of the most common sites of pressure ulcers, and the incidence rate in the elderly aged 70 years or older is high. Although there is literature on heel interface pressure, the heel interface pressure of the elderly in different postures has not yet been explored, which will be investigated in this study, as well as the effects of different foot positions. Their skin conditions will also be examined.

METHODS

Twenty-five females and twenty-six males, 70 years old or older, are evaluated while lying down, with only their naked foot in its natural position on a mattress, as well as placed on a standard or pressure-relieving mattress in different positions. The moisture, sebum content, and elasticity of the skin of the heel are tested.

FINDINGS

The heel of most of the participants is positioned at a 60°-69° or 90°-99° angle to the support surface. The heel interface pressure is the greatest when the foot is upright. The age, weight, and body mass index have no significant impacts. The moisture and sebum content are extremely low while elasticity is normal.

INTERPRETATION

The relaxed position of the foot is in neutral external rotation and upright positions. A greater amount of pressure is experienced when the foot is upright. The pressure-relieving mattress is more effective for reducing heel pressure but may not apply to all cases. Finally, the skin of the heel is dry and lacks sebum, which implies greater risk of developing heel sores.

Correlates of functional ankle instability in children and adolescents with Charcot-Marie-Tooth disease

BACKGROUND

Functional ankle instability (FAI) is commonly reported by children and adolescents with Charcot-Marie-Tooth disease (CMT), however,, the specific variables associated with FAI remain unknown. An improved understanding of these variables may suggest interventions to improve ankle stability and possibly prevent the long-term complications associated with ankle instability in this population. The aim of this study was to therefore investigate the relationship between FAI and other functional, structural, anthropometric and demographic characteristics in a cross sectional sample of children and adolescents with CMT.

METHODS

Thirty children and adolescents with CMT aged 7-18 years were recruited from the Peripheral Neuropathy Clinics of a large tertiary paediatric hospital. Measures of FAI were obtained using the Cumberland Ankle Instability Tool (CAIT). Demographic and anthropometric data was also collected. Other variables collected included foot structure (Foot Posture Index), ankle range of motion (weight bearing lunge) and functional parameters (balance, timed motor function and falls). Descriptive statistics were calculated to characterise the participants. Pearson's correlation coefficients were calculated to investigate the correlates of right and left FAI and demographic (age), anthropometric (height, weight, BMI), foot/ankle (foot structure and ankle flexibility) and functional parameters (balance task, timed motor function and falls frequency). Point biserial correlation was employed to correlate gender with right and left FAI.

RESULTS

All but one study participant (n = 29) reported moderate to severe bilateral FAI with females reporting significantly greater ankle instability than males. FAI was significantly associated with cavus foot structure (r = .69, P < .001), female gender (r = -.47, P < .001) and impaired balance (r = .50, P < .001).

CONCLUSIONS

This study confirms FAI is common in children and adolescents with CMT. An examination of the correlates of FAI suggests interventions, which target balance, and normalise foot structure should be explored to evaluate whether they might help to improve ankle stability in this population.

The relationship between paediatric foot posture and body mass index: do heavier children really have flatter feet?

Background

Several studies have found positive correlation between flatfeet and increased body mass in children. One study, utilizing a differing method of foot posture assessment, found the inverse. The purpose of this study was to further explore the relationship between children’s foot posture and body mass, utilizing the foot posture index in a large study population, as opposed to the footprint based measures of most previous studies.

Methods

Data for both foot posture index (FPI) and body mass index (BMI) for healthy children were acquired from five previous studies. The amalgamated dataset comprised observations for both BMI and FPI-6 in 728 children aged from three to 15 years. Three FPI-6 scores levels defined the range of flatfeet detected: FPI-6 ≥ +6; FPI-6 ≥ +8; FPI-6 ≥ +10. BMI cut-points were used to define overweight for each age group.

Results

In the study population of 728 children, flatfeet (FPI ≥ +6) were found in 290 (40 %) cases and non-flatfeet in 438 (60 %) cases. FPI ≥ +8 yielded flatfeet in 142 (20 %) cases and FPI ≥ +10 yielded flatfeet in 41 (5 %) cases. Whilst 272 (37 %) children were overweight, only 74 (10.1 %) of the overweight children had flatfeet (FPI ≥ +6), which diminished to 36 (4.9 %) at FPI ≥ +8, and 9 (1.2 %) at FPI ≥ +10.

Significant and moderate correlation was found between BMI and age (r = 0.384, p < 0.01). Very weak, but significant, correlation was found between BMI and FPI (r = −0.077, p < 0.05). Significant mean differences between gender and BMI were found (t-test = 2.56, p < 0.05). There was strong correlation between FPI scores on left and right sides (r = 0.899, p < 0.01).

Conclusions

This study found no association between increased body mass and flatfeet in children, a finding in contrast to that repeatedly concluded by many previous studies. Whilst properties of the FPI and BMI are limiting, these findings question the concern about children’s increased body mass as a specific influence on (flatter) foot posture, and also the validity of footprint versus anatomically based foot posture measures.

Dynamic in-vivo assessment of navicular drop while running in barefoot, minimalist, and motion control footwear conditions

Running-related injuries are common and previous research has suggested that the magnitude and/or rate of pronation may contribute to the development of these injuries. Accurately and directly measuring pronation can be challenging, and therefore previous research has often relied on navicular drop (under both static and dynamic conditions) as an indirect assessment of pronation. The objectives of this study were to use dynamic, biplane X-ray imaging to assess the effects of three footwear conditions (barefoot, minimalist shoes, motion control shoes) on the magnitude and rate of navicular drop during running, and to determine the association between static and dynamic measures of navicular drop. Twelve healthy distance runners participated in this study. The magnitude and rate of navicular drop were determined by tracking the 3D position of the navicular from biplane radiographic images acquired at 60Hz during the stance phase of overground running. Static assessments of navicular drop and foot posture were also recorded in each subject. Footwear condition was not found to have a significant effect on the magnitude of navicular drop (p=0.22), but motion control shoes had a slower navicular drop rate than running barefoot (p=0.05) or in minimalist shoes (p=0.05). In an exploratory analysis, static assessments of navicular drop and foot posture were found to be poor predictors of dynamic navicular drop in all footwear conditions (p>0.18).

A positive association between foot posture index and medial compartment knee osteoarthritis in moroccan people

Objectives :

To compare foot posture in people with and without medial compartment knee osteoarthritis (OA), and to assess association between its abnormalities and medial compartment knee OA.

Methods :

We compared the foot posture of patients with clinically and radiographically-confirmed medial compartment knee OA and asymptomatic healthy controls using the foot posture index (FPI), navicular height, and the medial arch.

Results :

We included 100 patients and 80 asymptomatic controls. The mean age of patients was 59 ± 7 (44-76) years and 48 ± 9 (28-60) years in the control (p=0.06). Patients group have more pronated foot for FPI (1.50 ± 2.68 vs 0.72 ± 2.63; p=0.05), more flat foot (42% vs 22%; p=0.03), and less pes cavus than the control group (58% vs 77%; p=0.004). However, there was no significant difference between the groups in the navicular height (3.90 ± 0.85 cm vs 4.00 ± 0.76 cm; p=0.41).

In multivariate statistical analysis, after adjusting for age and body mass index, pronated foot in FPI (OR=1.22, 95%IC= [1.06-1.40], p=0.005), and pes cavus (OR=0.32, 95%IC= [0.11-0.93], p=0.03) had a significant correlation with the knee osteoarthritis.

Conclusion :

Pronated foot posture and flat foot are significantly associated with medial compartment knee osteoarthritis.

Can static foot posture measurements predict regional plantar surface area?

BACKGROUND

The intent of this study was to determine if the use of a single or combination of static foot posture measurements can be used to predict rearfoot, midfoot, and forefoot plantar surface area in individuals with pronated or normal foot types.

METHODS

Twelve foot measurements were collected on 52 individuals (mean age 25.8 years) with the change in midfoot width used to place subjects in a pronated or normal foot mobility group. Dynamic plantar contact area was collected during walking with a pressure sensor platform. The 12 measures were entered into a stepwise regression analysis to determine the optimal set of measures associated with regional plantar surface area.

RESULTS

A two variable model was found to describe the relationship between the foot measurements and forefoot plantar contact area (r(2)=0.79, p<0.0001). A four variable model was found to describe the relationship between the foot measurements and midfoot plantar contact area (r(2)=0.85, p<0.0001) in those individuals with a 1.26cm or greater change in midfoot width.

CONCLUSIONS

The results indicate that clinicians can use a combination of simple, reliable and time efficient foot measures to explain 79% and 85% of the plantar surface area in the forefoot and midfoot, respectively.

Intra-rater and inter-rater reliability of the five image-based criteria of the foot posture index-6

PURPOSE/BACKGROUND

The Foot Posture Index-6 (FPI-6) is considered a simple quantification tool to assess static foot alignment. Palpation of the foot is required for assessment of one of the six criteria that comprise the FPI-6; the remaining five criteria may be evaluated using still-frame photographs. Using only the image-based criteria may allow multiple clinicians to evaluate large groups of patients quickly. Reliability using only these five image-based criteria has not been established. The purposes of the current study were to establish the inter- and intra-rater reliability using five image-based criteria from the Foot Posture Index-6 (FPI-6) as well as to examine the agreement between the raters in identifying foot type using the composite five FPI scores.

METHODS

Forty participants (23 females, 17 males; 23.67 ± 8.49 years; 64.59 ± 14.43 kg; 166.07 ± 11.79 cm) volunteered for this study. An investigator took three photos with a digital camera of the medial longitudinal arch, posterior ankle, and of the talonavicular joint approximately 45° from the posterior calcaneus for both right and left feet. Two investigators assessed the five image-based criteria of the FPI-6 for both feet of 40 participants on three occasions separated by a day. Inter-and intra-rater reliability were assessed with Intraclass Correlation Coefficients (ICC3,2). The amount of agreement for classification of foot posture type between the two raters was assessed with Cohen's kappa coefficient. Significance was set a priori at P < 0.05.

RESULTS

The inter-rater reliability was poor to moderate for all three sessions (ICC3,2 = 0.334-0.634). For the foot posture classification, the amount of agreement between two raters was poor for left (κ= 0.12) and right (κ= 0.19) feet. The intra-rater reliability was excellent for left (ICC3,2=0.956) and right feet (ICC3,2=0.959).

CONCLUSIONS

Excellent intra-rater and poor to moderate inter-rater reliability was found using only the five image-based criteria of the FPI-6. However, the classification of foot posture did not improve the amount of agreement between raters. Therefore, caution is needed when interpreting FPI scores from five image-based criteria.

LEVELS OF EVIDENCE

3b.

The effects of stance width and foot posture on lumbar muscle flexion-relaxation phenomenon

BACKGROUND

Characterizing the lumbar muscle flexion-relaxation phenomenon is a clinically relevant approach in understanding the neuromuscular alternations of low back pain patients. Previous studies have indicated that changes in stance posture could directly influence trunk kinematics and potentially change the lumbar tissue synergy. In this study, the effects of stance width and foot posture on the lumbar muscle relaxation responses during trunk flexion were investigated.

METHODS

Thirteen volunteers performed trunk flexion using three different stance widths and 'toe-forward' or 'toe-out' foot postures (six conditions in total). Lumbar muscle electromyography was collected from the L3 and L4 level paraspinals; meanwhile three magnetic motion sensors were placed over the S1, T12, and C7 vertebrae to track lumbar and trunk kinematics. The lumbar angle at which muscle activity diminished to a near resting level was recorded. At the systemic level, the boundary where the internal moment started to shift from active to passive tissues was identified.

FINDINGS

For the L3 paraspinals, the flexion relaxation lumbar angle reduced 1.3° with the increase of stance width. When changed from 'toe-forward' to 'toe-out' foot posture, the flexion relaxation lumbar angle reduced 1.4° and 1.1° for the L3 and L4 paraspinals respectively. However, the active and passive lumbar tissue load shifting boundary was not affected.

INTERPRETATION

Findings of this study suggest that changes in stance width and foot posture altered the lumbar tissue load sharing mechanism. Therefore, in a clinical setting, it is critical to maintain consistent stance postures when examining the characteristics of lumbar tissue synergy.

No association between q-angle and foot posture with running-related injuries: a 10 week prospective follow-up study

BACKGROUND/PURPOSE

There is a paucity of knowledge on the association between different foot posture quantified by Foot Posture Index (FPI) and Quadriceps angle (Q-angle) with development of running-related injuries. Earlier studies investigating these associations did not include an objective measure of the amount of running performed. Therefore, the purpose of this study was to investigate if kilometers to running-related injury (RRI) differ among novice runners with different foot postures and Q-angles when running in a neutral running shoe.

METHODS

A 10 week study was conducted including healthy, novice runners. At baseline foot posture was evaluated using the foot posture index (FPI) and the Q-angle was measured. Based on the FPI and Q-angle, right and left feet / knees of the runners were categorized into exposure groups. All participants received a Global Positioning System watch to allow them to quantify running volume and were instructed to run a minimum of two times per week in a conventional, neutral running shoe. The outcome was RRI.

RESULTS

Fifty nine novice runners of mixed gender were included. Of these, 13 sustained a running-related injury. No significant difference in cumulative relative risk between persons with pronated feet and neutral feet was found after 125 km of running (Cumulative relative risk = 1.65 [0.65; 4.17], p = 0.29). Similarly, no difference was found between low and neutral Q-angle (Cumulative relative risk = 1.25 [0.49; 3.23], p = 0.63).

CONCLUSION

Static foot posture as quantified by FPI and knee alignment as quantified by Q-angle do not seem to affect the risk of injury among novice runners taking up a running regimen wearing a conventional neutral running shoe. These results should be interpreted with caution due to a small sample size.

LEVEL OF EVIDENCE

2a.

The effects of prolonged running on foot posture: a repeated measures study of half marathon runners using the foot posture index and navicular height

Background

Different foot postures are associated with alterations in foot function, kinetics and the subsequent occurrence of injury. Little is known about changes in foot posture following prolonged weightbearing exercise. This study aimed to identify changes in foot posture after running a half marathon.

Methods

Foot posture was measured using the Foot Posture Index (FPI-6) and navicular height in thirty volunteer participants before and after running a half marathon. FPI-6 scores were converted to Rasch logit values and means compared for these and navicular height using an ANOVA.

Results

There was a 5 mm drop in navicular height in both feet when measured after the half marathon (P < 0.05). The FPI-6 showed a side x time interaction with an increase in score indicating a more ‘pronated’ position in the left foot of + 2 [Rasch value + 1.7] but no change in the right foot (+ 0.4 [+ 0.76]) following the half marathon.

Conclusion

The apparent differences between the FPI-6 and navicular height on the right foot may be because the FPI-6 takes soft tissue contour changes into consideration whilst the navicular height focuses on skeletal changes. The changes in foot posture towards a more pronated position may have implications for foot function, and therefore risk of injury; shoe fit and comfort and also the effect of therapeutic orthoses worn during prolonged running.