Center Of Pressure Excursion Index Research Articles

Effects of short foot exercise combined with lower extremity training on dynamic foot function in individuals with flexible flatfoot: A randomized controlled trial

BackgroundFlexible flatfoot has demonstrated biomechanical linkages between distal and proximal lower extremities. However, supporting evidence is required to investigate the benefits of short foot exercise (SF) and short foot exercise in combination with lower extremity training (SFLE) on dynamic foot function. Research questionThis study aimed to determine the effects of a 6-week SF, 6-week SFLE, or control condition (no intervention) on dynamic foot function during gait in individuals with flexible flatfoot. MethodsForty-five individuals with flexible flatfoot were randomly assigned into three conditions: (1) SF, (2) SFLE, and (3) control conditions. Participants in two intervention programs performed daily training via telerehabilitation and a home-based exercise program. Foot kinematics and center of pressure excursion index (CPEI) during the gait, intrinsic foot muscle test, and navicular drop test were assessed at baseline and after the 6-week intervention program. ResultsPost-intervention participants in the SF and SFLE conditions showed a shorter time to the lowest medial longitudinal arch (MLA) and improved MLA motion during the stance phase compared with the baseline. In addition, participants in the SFLE conditions showed greater changes in CPEI than in the SF and control conditions. Improvements in intrinsic foot muscle and navicular drop tests were also observed in participants in both intervention programs post-intervention. SignificanceA major finding of the study was the improvement in dynamic foot function during gait in individuals with flexible flatfoot after the six weeks of the SF and SFLE intervention programs. Both intervention programs appear to have the potential for inclusion in a corrective program for individuals with flexible flatfoot.

Feature Selection, Construction, and Validation of a Lightweight Model for Foot Function Assessment During Gait With In-Shoe Motion Sensors

Identifying and monitoring overpronation and oversupination in the long term during activities of daily living is essential for people’s ambulatory health. Using an in-shoe motion sensor (IMS) with power-saving functions is a potential solution. In this study, we challenged the development of an estimation model of foot function using the foot center of pressure excursion index (CPEI) as an index via linear multivariate regression, which is sufficiently light for this type of IMS. Data collected from 65 and 17 participants were involved in model construction and validation, respectively. We validated ten scenarios simulating daily living activities, including walking on different surfaces, using different shoes, with or without carrying a bag, and indoors and outdoors. We applied statistic parametric mapping (SPM) to determine significant predictors and performed our original feature selection algorithm, leave-one-subject-out LASSO, to compress the volume of the predictors. We successfully discovered significant sex-specific predictors for foot function estimation from foot motion and constructed large effect-sized sex-specific foot function estimation models that achieved high-precision CPEI estimation. In the validation, the model successfully estimated a maximum of 99.0% and 100.0% males’ and females’ data under the same experimental conditions with the training data and 92.8–100.0% and 85.8–100.0% data in different scenarios. The constructed models are effective and possible to provide applications for long-term foot function monitoring by using an IMS.

Comparing the effects of University of California Biomechanics Laboratory and custom-made semi-rigid insole on pedobarographic parameters in pediatric flexible flat foot.

Pediatric flexible flat foot (PFFF) is often associated with pain along the medial longitudinal arch and potential disability. There are several conservative treatment options for PFFF, ranging from intrinsic muscle exercises to orthosis, including University of California Biomechanics Laboratory (UCBL) and custom-made semi-rigid insoles. To investigate and compare the effect of UCBL and custom-made semi-rigid insoles on pedobarographic and radiologic parameters in PFFF. This study prepared a retrospective chart review of 143 children diagnosed with PFFF between the age of 4 and 12 years. Data of twenty-seven children with PFFF who were prescribed foot orthoses between the age of 4 and 12 years were retrospectively reviewed. Medical charts were retrospectively reviewed, and pedobarographic and radiological parameters assessed before and 1 year after application of orthoses were reviewed. The difference in the calcaneal pitch angle and the center of pressure excursion index (CPEI) were significantly improved in the custom-made semi-rigid insole group compared to that in the UCBL group. The contact area ratio of the midfoot and toe and CPEI at 1 year after wearing the insole was significantly improved in the custom-made semi-rigid insole group compared to that in the UCBL group. Moreover, the calcaneal pitch angle and CPEI were significantly improved 1 year after application of the insole in the custom-made semi-rigid insole group. This result showed that the custom-made semi-rigid insole is more effective in improving the deviation of the center pressure curve and calcaneal pitch angle than the UCBL. The custom-made semi-rigid insole may help relieve foot instability during gait and improve the medial longitudinal arch in children with PFFF.

The Impact of Progressive Collapsing Foot Deformity on Foot & Ankle Kinematics and Plantar Pressure During Simulated Gait

Category:Basic Sciences/Biologics; HindfootIntroduction/Purpose:Progressive collapsing foot deformity (PCFD) is a 3-dimensional pathology associated with insufficiency of the posterior tibial tendon (PTT), ligamentous failure, joint malalignment, and aberrant plantar force distribution. Existing knowledge of PCFD consists of static measurements, which provide information about the structure of the foot but none about its function. Cadaveric gait models provide an opportunity to measure motion both at the joints primarily affected in PCFD and the adjacent joints that are at risk for progressive subluxation and arthritis. This study sought to develop a flatfoot model for a robotic gait simulator and quantify gait kinematics and plantar pressure between normal and flatfoot conditions, which we hypothesized would be altered after the creation of a flatfoot deformity model.Methods:Cadaveric specimens were loaded on a 6-degree of freedom robotic gait simulator and the extrinsic tendons were attached to linear motors. Ground reaction forces and muscle forces were optimized utilizing an established iterative process. An 8-camera motion capture system was utilized to calculate joint kinematics using reflective markers attached by k-wires into bone. A plantar pressure mat attached to the force platform was used to calculate the center of pressure excursion index (CPEI) for each condition. The flatfoot model was created via sectioning of the spring ligament and medial talonavicular joint capsule followed by cyclic axial compression until 5-15° of talonavicular abduction was achieved in a static, loaded pose. Testing of the flatfoot state was then performed with inactivation of the PTT. Bias-corrected bootstrapped 95% confidence intervals were constructed from the repeated measures difference between flatfoot and normal conditions. Paired t-tests were used to compare the CPEI between conditions.Results:Twelve mid-tibia cadaveric specimens (mean age 73 years, 8 female) with no prior foot/ankle surgery were used. There were significant differences in kinematics between normal and PCFD conditions at the ankle, subtalar, and talonavicular joints (Figure). There was significantly increased ankle plantar flexion in flatfoot in the first 80% of stance phase. There was significantly greater subtalar eversion in flatfoot compared to normal from 10-90% of stance phase. Talonavicular abduction and eversion were also significantly greater in flatfoot from 10-100% of stance. The CPEI was significantly decreased in the flatfoot condition (Figure), indicating a medialization in center of pressure (p<0.0001).Conclusion:The results from this study support our hypothesis of altered kinematics and plantar pressure after flatfoot deformity creation and corroborate previous biomechanical studies of static alignment in PCFD. Increased talonavicular abduction and subtalar eversion are hallmarks of flatfoot deformity, and increased ankle plantarflexion may represent the plantarflexed position of the talus in PCFD. In addition, plantar pressure was significantly medialized with flatfoot deformity. These findings highlight the utility of the gait simulator as a tool for future study of PCFD, especially for analysis of deformity patterns and the specific effects of individual interventions.

The biomechanical effects of pronated foot function on gait. An experimental study.

The relationship between foot kinematics and the development of lower extremity musculoskeletal disorders (MSD) has been the focus of recent attention. However, most studies evaluated static foot type and not dynamic foot function. The purpose was to compare lower limb and foot kinematics, and plantar pressures during gait in physically active individuals with pronated and non-pronated foot function. Foot function in 154 adult participants was documented as pronated (n=63) or neutral (n=91) using 2 established methods: The Foot Posture Index and the Center of Pressure Excursion Index. Difference between the groups in triplanar motion of the lower limb during barefoot gait was evaluated using a 3D motion capture system incorporating the Oxford Foot Model. Dynamic parameters of plantar pressure were recorded using a pressure platform. Anterior-posterior pelvic tilt range of motion (ROM), peak knee internal rotation, forefoot dorsiflexion ROM, peak forefoot abduction, and rearfoot eversion were all increased in those with pronated foot function. Hallux contact time and time to peak force under the medial forefoot were increased with pronated foot function, and maximal force under the lateral forefoot was reduced. Pronated foot function affected the whole lower limb kinematic chain during gait. These kinematic alterations could increase the risk of developing MSD. Further studies should elucidate the relationship between pronated foot function and MSD, and, if confirmed, foot function should be evaluated in clinical practice for patients with lower limb and low back pain.

The Association of Parity with Greater Dynamic Pronation of the Feet.

Postpartum women are at increased risk for lower limb musculoskeletal disorders. Foot arch collapse following pregnancy has been reported as a mechanism for this increased risk. However, dynamic changes during gait in postpartum women have not been reported. Therefore, we assessed the association between parity and dynamic foot pronation during gait. To determine (1) if there is an association between parity and dynamic foot pronation (center of pressure excursion index, CPEI) during gait; and (2) the extent to which there is a dose-effect of parity on foot pronation. The Multicenter Osteoarthritis Study (MOST) Study is a longitudinal cohort study of adults with or at risk for knee osteoarthritis (OA). Two communities in the United States, Birmingham, Alabama and Iowa City, Iowa. Not applicable PARTICIPANTS: A population-based sample of 1177 MOST participants who were female, had complete CPEI and parity data and completed the baseline, 30- and 60-month visits. Odds of a one quintile decrease in CPEI by parity group and mean CPEI by parity group. In 1177 women, mean age was 67.7 years and mean body mass index (BMI) was 30.6 kg/m2 . As parity increased, there was significantly greater foot pronation, lower mean CPEI: 19.1 (18.2-20.1), 18.9 (18.4-19.4), 18 (17.5-18.6) to 17.5 (16.4-18.6) in the 0 to 4 and >5 children groups, respectively; (P = .002), which remained significant after adjusting for race and clinic site (P = .005). There was a positive linear trend (β = 1.08, 1.03-1.14) in odds ratios of a one quintile decrease in CPEI (greater pronation) with increasing parity level (P = .004), which remained significant after adjusting for race and clinic site (P = .01). After adjusting for age and BMI, these two associations were no longer statistically significant. This study indicates a positive correlation between parity and greater dynamic pronation of the feet.

Center of pressure limb path differences for the detection of lameness in dogs: a preliminary study

BackgroundThe limb center of pressure (COP) path measures and quantifies the load distribution within a limb in a still or moving subject. Under this premise, the aim of this study was to test whether data derived from this parameter could detect the differences between sound and lame limbs in unilaterally lame dogs with elbow dysplasia.To accomplish this purpose, ten unilaterally lame dogs of similar conformation were walked over a pressure platform. Next, the COP path, in relation to the position of sound and lame limbs, was measured in a coordinate system over a standard paw template obtained by pedobarography during the whole support phase. To compare variables, force platform data (peak vertical force and vertical impulse) from the same animals were obtained. Sound and lame limb statokinesiograms were also obtained while the animals stood still.ResultsThe statistical analysis clearly showed that COP in lame limbs start cranially and were shorter than sound limbs. In addition, the value of the COP excursion index was lower in lame limbs. Finally, the area of statokinesiograms was greater in lame limbs.ConclusionThis methodology based in limb COP characteristics serves to discriminate between sound and lame limbs in dogs with elbow dysplasia.

Static and dynamic effects of customized insoles on attenuating arch collapse with pregnancy: A randomized controlled trial

IntroductionAnthropometric changes to the feet with pregnancy may increase risk for musculoskeletal disease. Customized arch-supportive orthoses to prevent anthropometric changes could potentially provide an inexpensive means to prevent musculoskeletal impairments and improve quality of life for women during their post-reproductive years. The objective of this prospective, randomized controlled trial was to determine whether customized foot orthoses can prevent arch collapse during pregnancy. Materials and methodsSeventy-two first trimester women (age 18–40) were randomized to wear either their usual footwear (control) or their usual footwear with custom-molded arch-supportive orthoses. Each participant in the customized orthosis group had orthoses customized by a certified orthotist. Baseline assessments were completed during the first trimester and follow-up assessments were completed approximately 8 weeks postpartum. The primary outcome measurements were static arch height index (AHI), arch drop, arch rigidity index, and center of pressure excursion index (CPEI). ResultsThere were no statistically significant differences in the change in static foot structure or dynamic arch function between baseline and follow-up within either group. Comparing the customized orthosis and control groups, no significant differences were detected in change in AHI sitting (p=.44), AHI standing (p=.48), arch drop (p=.67), arch rigidity (p=.68) or CPEI (p=.77). ConclusionsThere was no difference in arch change when comparing women who were randomized to wear customized orthoses or self-selected footwear. The finding of no arch drop in either group may indicate that both groups supported their arches during the study period or that neither group was predisposed to lose arch height with pregnancy.

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

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

Concurrent validity of an automated algorithm for computing the center of pressure excursion index (CPEI)

Center of Pressure Excursion Index (CPEI), a parameter computed from the distribution of plantar pressures during stance phase of barefoot walking, has been used to assess dynamic foot function. The original custom program developed to calculate CPEI required the oversight of a user who could manually correct for certain exceptions to the computational rules. A new fully automatic program has been developed to calculate CPEI with an algorithm that accounts for these exceptions. The purpose of this paper is to compare resulting CPEI values computed by these two programs on plantar pressure data from both asymptomatic and pathologic subjects. If comparable, the new program offers significant benefits—reduced potential for variability due to rater discretion and faster CPEI calculation. CPEI values were calculated from barefoot plantar pressure distributions during comfortable paced walking on 61 healthy asymptomatic adults, 19 diabetic adults with moderate hallux valgus, and 13 adults with mild hallux valgus. Right foot data for each subject was analyzed with linear regression and a Bland-Altman plot. The automated algorithm yielded CPEI values that were linearly related to the original program (R2=0.99; P<0.001). Bland-Altman analysis demonstrated a difference of 0.55% between CPEI computation methods. Results of this analysis suggest that the new automated algorithm may be used to calculate CPEI on both healthy and pathologic feet.

Impact of Arch Height Flexibility on Dynamic Plantar Pressure in Healthy Young Subjects with Planus Feet

INTRODUCTION AND OBJECTIVES: Healthy feet are important for overall health and well-being. Previous studies of older subjects showed that those with a lowered arch had an increased odds of having foot deformities, pain, and hyperpronation in gait. (1–3) No investigation to date has comprehensively characterized foot biomechanics in a large sample of healthy active young subjects. METHODS: Foot structure, function, and arch height flexibility (AHF) were measured in 1,052 incoming cadets to the United States Military Academy. Based on the previously established standing arch height index (AHI), 70% of subjects exhibited planus foot structures. (4,5) To examine the effects of AHF on dynamic barefoot plantar pressure, 1,414 planus feet were further categorized by AHF. Those that fell within the highest and the lowest quintiles were defined as flexible and stiff AHF, respectively, while the middle 3 quintiles were categorized as referent. RESULTS: Descriptive statistics and normality testing were performed using SPSS software version 22 (IBM, Chicago, IL, USA). A Generalized Linear Model with an identify link function was used to examine the effects of AHF category while accounting for potential dependence in bilateral data. The Wald Chi-square was calculated for each dependent variable with significance set at p &amp;lt; 0.05. Post hoc pairwise comparisons for all pairs were performed using the Generalized Chi Square test at P &amp;lt; 0.017. CONCLUSIONS: A significant difference was found in Center of Pressure Excursion Index (CPEI) and Peak Pressure (PP). Post hoc pairwise comparisons showed a significant difference between flexible versus stiff AHF: those with flexible AHF exhibited reduced CPEI (greater hyperpronation) while those with stiff AHF showed elevated PP. Results suggest that, in addition to AHI, the arch flexibility may affect dynamic foot function. This was a part of larger study. Additional studies are needed to examine the effects of AHI and AHF on regional plantar loading and overuse injuries.

Foot disorders associated with overpronated and oversupinated foot function: the Johnston County osteoarthritis project.

The occurrence of musculoskeletal foot disorders differs by race and obesity, and these disorders may be related to pronated (low arch) or supinated (high arch) foot structure. This cross-sectional analysis examined relationships of foot disorders and foot function by race and obesity in a community-based observational study of adults 50+ years old with and without osteoarthritis. Members of a prospective cohort study in North Carolina were included in this analysis (N = 1466, 67.2% women, 29.5% African American, mean age 68.5 years). Foot disorders were identified with a validated assessment tool, and each foot was categorized as overpronated, oversupinated, and referent using the center of pressure excursion index from foot pressure scans during normal-paced walking. Logistic regression models estimated associations between foot function and each foot disorder with age, body mass index (BMI), gender, and race as covariates. Compared to referent, an overpronated foot was associated with hallux valgus (adjusted odds ratio [aOR] 1.36, 95% confidence interval [CI] 1.13-1.65) and overlapping toes (aOR 1.36, 95% CI 1.12-1.64), especially in the obese. An oversupinated foot was inversely associated with hallux valgus (aOR 0.85, 95% CI 0.74-0.97). An oversupinated foot was less likely to be associated with bunionettes among the obese and was more likely to be associated with plantar fasciitis in Caucasians. Foot function was related to hallux valgus and overlapping toes, especially among the obese. In clinical patients as well as in the community of older adults, treatments for both the foot disorder and the pronated/supinated foot may be needed. Level II, comparative cohort study.

Dynamic barefoot plantar pressure in gait and foot type biomechanics

Song et al demonstrated that healthy subjects with planus and neutral foot type exhibited a distinguishable foot posture and dynamic foot function [1]. However, such a relationship has not been demonstrated in a large sample study. Foot structure was categorized into one of three foot types (cavus, neutral, and planus) based on the standing arch height index (AHI) in 1,054 incoming cadets at the US Military Academy (172 female, 18.5±1.1 years, 24.5±3.0 kg/m2) [2]. Five trials of barefoot dynamic planar pressure were obtained for each foot with the Novel emed-x (novel GmbH, Munich) using the two-step method for walking data acquisition. The Center of Pressure Excursion Index (CPEI, %) and the peak pressure (PP, in kiloPascal) were calculated for each trial. Analysis of Variance was performed across the foot type groups on the left foot. The cavus group exhibited the largest CPEI while the planus group demonstrated the smallest CPEI. The neutral group demonstrated the lowest peak pressure, which was significantly lower than the planus group. Results of this study provide additional evidence which support the link between the dynamic plantar pressure in gait and foot type biomechanics. Table 1 The mean Center of Pressure Excursion Index and the Peak Pressure are shown for three foot type groups. The analysis was limited to left foot only.

Association of Planus Foot Posture and Pronated Foot Function With Foot Pain: The Framingham Foot Study

To examine the associations of foot posture and foot function to foot pain. Data were collected on 3,378 members of the Framingham Study cohort who completed foot examinations in 2002-2008. Foot pain (generalized and at 6 locations) was based on the response to the following question: "On most days, do you have pain, aching or stiffness in either foot?" Foot posture was categorized as normal, planus, or cavus using static pressure measurements of the arch index. Foot function was categorized as normal, pronated, or supinated using the center of pressure excursion index from dynamic pressure measurements. Sex-specific multivariate logistic regression models were used to examine the effect of foot posture and function on generalized and location-specific foot pain, adjusting for age and weight. Planus foot posture was significantly associated with an increased likelihood of arch pain in men (odds ratio [OR] 1.38, 95% confidence interval [95% CI] 1.01-1.90), while cavus foot posture was protective against ball of foot pain (OR 0.74, 95% CI 0.55-1.00) and arch pain (OR 0.64, 95% CI 0.48-0.85) in women. Pronated foot function was significantly associated with an increased likelihood of generalized foot pain (OR 1.28, 95% CI 1.04-1.56) and heel pain (OR 1.54, 95% CI 1.04-2.27) in men, while supinated foot function was protective against hindfoot pain in women (OR 0.74, 95% CI 0.55-1.00). Planus foot posture and pronated foot function are associated with foot symptoms. Interventions that modify abnormal foot posture and function may therefore have a role in the prevention and treatment of foot pain.

Associations of Foot Posture and Function to Lower Extremity Pain: Results From a Population‐Based Foot Study

Studies have implicated foot posture and foot function as risk factors for lower extremity pain. Empirical population-based evidence for this assertion is lacking; therefore, the purpose of this study was to evaluate cross-sectional associations of foot posture and foot function to lower extremity joint pain in a population-based study of adults. Participants were members of the Framingham Foot Study. Lower extremity joint pain was determined by the response to the National Health and Nutrition Examination Survey-type question, "On most days do you have pain, aching or stiffness in your (hips, knees, ankles, or feet)?" The Modified Arch Index classified participants as having planus, rectus (referent), or cavus foot posture. The Center of Pressure Excursion Index classified participants as having overpronated, normal (referent), or oversupinated foot function. Crude and adjusted (age, sex, and body mass index) logistic regression determined associations of foot posture and function to lower extremity pain. Participants with planus structure had higher odds of knee (odds ratio [OR] 1.57, 95% confidence interval [95% CI] 1.24-1.99) or ankle (OR 1.47, 95% CI 1.05-2.06) pain, whereas those with a cavus foot structure had increased odds of ankle pain only (OR 7.56, 95% CI 1.99-28.8) and pain at 1 lower extremity site (OR 1.37, 95% CI 1.04-1.80). Associations between foot function and lower extremity joint pain were not statistically significant except for a reduced risk of hip pain in those with an oversupinated foot function (OR 0.69, 95% CI 0.51-0.93). These findings offer a link between foot posture and lower extremity pain, highlighting the need for longitudinal or intervention studies.

Foot disorders, foot posture, and foot function: the Framingham foot study.

IntroductionFoot disorders are common among older adults and may lead to outcomes such as falls and functional limitation. However, the associations of foot posture and foot function to specific foot disorders at the population level remain poorly understood. The purpose of this study was to assess the relation between specific foot disorders, foot posture, and foot function.MethodsParticipants were from the population-based Framingham Foot Study. Quintiles of the modified arch index and center of pressure excursion index from plantar pressure scans were used to create foot posture and function subgroups. Adjusted odds ratios of having each specific disorder were calculated for foot posture and function subgroups relative to a referent 3 quintiles.ResultsPes planus foot posture was associated with increased odds of hammer toes and overlapping toes. Cavus foot posture was not associated with the foot disorders evaluated. Odds of having hallux valgus and overlapping toes were significantly increased in those with pronated foot function, while odds of hallux valgus and hallux rigidus were significantly decreased in those with supinated function.ConclusionsFoot posture and foot function were associated with the presence of specific foot disorders.

Survival on controlled-release morphine versus controlled-release oxycodone in opioid-naïve patients with non-malignant pain: data from Danish national health registers

mingham Foot Study. A validated exam of the foot was used to assess the presence of hallux valgus, hallux rigidus, and plantar fasciitis. To determine foot type, center of pressure excursion index (CPEI) measurements were recorded using the TekScan Matscan (1.4 sensors/ cm2) system. CPEI is a dynamic measure of foot type that uses the concavity of the center of pressure curve in the metatarsal head region, normalized to foot width during the stance phase of gait. In a prior study by Hillstrom et al., utilizing the emed-x plantar pressure system (4 sensors/cm2), CPEI thresholds discriminated planus, rectus (normal arch), and cavus (high arch) feet. Due to the differences in system resolution, a scaling equation was developed in order to determine the equivalent CPEI threshold on a TekScan Matscan system that differentiated planus from non-planus (rectus and cavus) feet. This threshold was defined as a CPEI 19.4% on a TekScan Matscan system. Crude and adjusted logistic regression models, using generalized estimating equations (GEE) to account for the correlation between left and right feet, were used to calculate odds ratios for the relation between foot type and the prevalence of hallux rigidus, hallux valgus, and plantar fasciitis. Adjusted models included age, sex and body mass index (BMI). Results: This study included 2,994 participants (5,778 feet) with an age range of 36-98 years and 55% women. The results are shown in Table 1. Approximately 74% of the study population (mean age1⁄465.5 9.9 years) was classified as having pes planus in at least one foot. Those with flat feet were at an increased odds for hallux valgus (OR 1.6, 95% CI 1.4, 1.8) and hallux rigidus (OR 1.6, 95% CI 1.1, 2.3). These results remained significant when adjusted for age, gender, and BMI. Conclusions: Those with planus foot type had a higher odds of hallux valgus and hallux rigidus, but not plantar fasciitis. The high prevalence rate of pes planus in the Framingham cohort may be because the average participant is 66 years old and arch height has been shown to decrease with age. Further, CPEI recordings may be more sensitive to less severe cases of pes planus, contributing to this high prevalence rate. Hallux valgus and hallux rigidus was more prevalent in pes planus versus non-planus feet. This is important because foot structure and function are potentially modifiable factors for these pathologies that have implications for prevention and treatment.

Pregnancy Leads to Lasting Changes in Foot Structure

Women are disproportionately affected by musculoskeletal disorders. Parous women seem to be at a particularly elevated risk for structural and functional changes in the lower limbs. The combination of increased weight on the joints with potentially greater laxity during pregnancy could lead to permanent structural changes in the feet. Although arches may become lax during pregnancy, it is unknown whether the changes persist. The objective of this study was to determine whether arch height loss persists postpartum. Forty-nine women completed this longitudinal study. Static and dynamic arch measurements were collected in the first trimester and at 19 wks postpartum. Linear mixed models were used to determine whether outcome measures significantly changed overall or by parity. Arch height and rigidity indices significantly decreased, with concomitant increases in foot length and arch drop. The first pregnancy accounted for the reduction in arch rigidity and the increases in foot length and arch drop. No changes were detected in the center of pressure excursion index. Pregnancy seems to be associated with a permanent loss of arch height, and the first pregnancy may be the most significant. These changes in the feet could contribute to the increased risk for musculoskeletal disorders in women. Further research should assess the efficacy of rehabilitative interventions for prevention of pregnancy-related arch drop.

Factors affecting center of pressure in older adults: the Framingham Foot Study

BackgroundAlthough aberrant foot movement during gait has been associated with adverse outcomes in the lower extremities in clinical patients, few studies have analyzed population differences in foot function. The purpose of this study was to assess demographic differences in foot function in a large population-based study of community-dwelling adults.MethodsParticipants in this study were from the Framingham Foot Study. Walking data were collected from both feet using a Tekscan Matscan pressure mat. Foot function was characterized using the center of pressure excursion index (CPEI). T-tests were used to assess differences between population subsets based on sex, and in men and women separately, age, body mass index (BMI), physical activity and in women, past high heel use.ResultsThere were 2111 participants included in this analysis. Significant differences in CPEI were noted by sex (p< 0.0001), by age in women (p = 0.04), and by past high heel use in women (p = 0.04).ConclusionsFoot function during gait was affected by sex, as well as by age and shoe-wear in women, but not by BMI or physical activity. Future work will evaluate possible relations between CPEI and outcomes such as falls, sarcopenia, and lower extremity function.

Hallux valgus and plantar pressure loading: the Framingham foot study

BackgroundHallux valgus (HV), a common structural foot deformity, can cause foot pain and lead to limited mobility. The purpose of this study was to evaluate differences in plantar pressure and force during gait by HV status in a large population-based cohort of men and women.MethodsA trained examiner performed a validated physical examination on participants’ feet and recorded the presence of hallux valgus and other specific foot disorders. Each foot was classified into one of four mutually exclusive groups based on the foot examination. Foot groups were: (i) HV only, (ii) HV and at least one additional foot disorder (FD), (iii) no HV but at least one other FD, and (iv) neither HV nor FD (referent). Biomechanical data for both feet were collected using Tekscan Matscan. Foot posture during quiet standing, using modified arch index (MAI), and foot function during gait, using center of pressure excursion index (CPEI), were calculated per foot. Further, walking scans were masked into eight sub-regions using Novel Automask, and peak pressure and maximum force exerted in each region were calculated.ResultsThere were 3205 participants, contributing 6393 feet with complete foot exam data and valid biomechanical measurements. Participants with HV had lower hallucal loading and higher forces at lesser toes as well as higher MAI and lower CPEI values compared to the referent. Participants with HV and other FDs were also noted to have aberrant rearfoot forces and pressures.ConclusionsThese results suggest that HV alters foot loading patterns and pressure profiles. Future work should investigate how these changes affect the risk of other foot and lower extremity ailments.