Jinsup Song

Foot type biomechanics. comparison of planus and rectus foot types.

The basic premise central to the diagnosis and treatment of most mechanogenic foot and ankle pathologies is that a given foot will display a characteristic function depending on the biomechanical alignment of the hindfoot and forefoot. However, the effects of foot type on an individuals ability to perform comfortable cadence locomotion have not been scientifically proven. Therefore, this study was conducted on 21 healthy, young subjects (10 subjects with planus foot type and 11 subjects with rectus foot type) to test whether different foot types yield distinguishable foot functions. New methods were developed to quantify biomechanical foot function during posture and comfortable cadence locomotion. The results of the study indicate that individuals with planus and rectus foot types show statistically significant differences in the biomechanical function of the foot.

Arch height index measurement system: establishment of reliability and normative values.

BACKGROUND The purposes of this study were 1) to determine the intrarater and interrater reliability of the arch height index measurement system device, 2) to establish population normative values for the arch height index in recreational runners, and 3) to compare arch height index values between the right and left feet and between genders. METHODS Eleven subjects were used to establish intrarater and interrater reliability of the arch height index measurement system. This system was then used to measure the arch height index of 100 recreational runners. RESULTS Measurements taken with the arch height index measurement system device exhibited high intrarater and interrater reliability. The mean +/- SD arch height index of the recreational runners was 0.340 +/- 0.030. Men had larger feet than women, but the arch height index between genders was similar. CONCLUSIONS The arch height index measurement system device is reliable to use between testers while simplifying the measurement procedure for recording the arch height index. The arch height index may be helpful in identifying potential structural factors that predispose individuals to lower-extremity injuries.

The Effect of Gender, Age, and Lateral Dominance on Arch Height and Arch Stiffness:

Background: Arch structure is known to vary widely. However, it may be linked to intrinsic factors such as gender, age, and lateral dominance. Understanding the association between these factors and arch structure may be useful in understanding injury biases that exist between individuals with different foot types. Methods: The foot structure of 145 subjects, 68 men and 77 women (18 to 65 years) was examined in this study. The arch height index, a measure of dorsal height normalized to foot length, and arch stiffness of both feet were measured in each subject. Comparisons of both arch height and arch stiffness were made between genders and between the dominant and nondominant feet. In addition, the relationship between both arch height and stiffness and age was examined. Results: There was no difference between the arch height index of men and women; however, the arches in women were significantly less stiff (p = 0.00). There were no statistically significant relationships between increasing age and either arch height index or stiffness. The within-subject comparisons showed that the dominant foot had a significantly higher arch height index than the nondominant foot (p = 0.00). However, arch stiffness was not different between sides. There was a significant, but weak, relationship between arch height index and arch stiffness (p = 0.00, R 2 = 0.09) with a higher arch height index corresponding to a stiffer arch. Conclusion: Understanding differences in arch structure may lend insight into the predilection for injury between genders, with increasing age, and between sides of a given subject.

Foot type biomechanics part 1: Structure and function of the asymptomatic foot

BACKGROUND Differences in foot structure are thought to be associated with differences in foot function during movement. Many foot pathologies are of a biomechanical nature and often associated with foot type. Fundamental to the understanding of foot pathomechanics is the question: do different foot types have distinctly different structure and function? AIM To determine if objective measures of foot structure and function differ between planus, rectus and cavus foot types in asymptomatic individuals. METHODS Sixty-one asymptomatic healthy adults between 18 and 77 years old, that had the same foot type bilaterally (44 planus feet, 54 rectus feet, and 24 cavus feet), were recruited. Structural and functional measurements were taken using custom equipment, an emed-x plantar pressure measuring device, a GaitMat II gait pattern measurement system, and a goniometer. Generalized Estimation Equation modeling was employed to determine if each dependent variable of foot structure and function was significantly different across foot type while accounting for potential dependencies between sides. Post hoc testing was performed to assess pair wise comparisons. RESULTS Several measures of foot structure (malleolar valgus index and arch height index) were significantly different between foot types. Gait pattern parameters were invariant across foot types. Peak pressure, maximum force, pressure-time-integral, force-time-integral and contact area were significantly different in several medial forefoot and arch locations between foot types. Planus feet exhibited significantly different center of pressure excursion indices compared to rectus and cavus feet. CONCLUSIONS Planus, rectus and cavus feet exhibited significantly different measures of foot structure and function.

Effects of Pediatric Obesity on Joint Kinematics and Kinetics During 2 Walking Cadences

UNLABELLED Shultz SP, Sitler MR, Tierney RT, Hillstrom HJ, Song J. Effects of pediatric obesity on joint kinematics and kinetics during 2 walking cadences. OBJECTIVE To determine whether differences existed in lower-extremity joint biomechanics during self-selected walking cadence (SW) and fast walking cadence (FW) in overweight- and normal-weight children. DESIGN Survey. SETTING Institutional gait study center. PARTICIPANTS Participants (N=20; mean age +/- SD, 10.4+/-1.6y) from referred and volunteer samples were classified based on body mass index percentiles and stratified by age and sex. Exclusion criteria were a history of diabetes, neuromuscular disorder, or recent lower-extremity injury. INTERVENTIONS Not applicable. MAIN OUTCOME MEASURES Sagittal, frontal, and transverse plane angular displacements (degrees) and peak moments (newton meters) at the hip, knee, and ankle joints. RESULTS The level of significance was set at P less than .008. Compared with normal-weight children, overweight children had greater absolute peak joint moments at the hip (flexor, extensor, abductor, external rotator), the knee (flexor, extensor, abductor, adductor, internal rotator), and the ankle (plantarflexor, inverter, external/internal rotators). After including body weight as a covariate, overweight children had greater peak ankle dorsiflexor moments than normal-weight children. No kinematic differences existed between groups. Greater peak hip extensor moments and less peak ankle inverter moments occurred during FW than SW. There was greater angular displacement during hip flexion as well as less angular displacement at the hip (extension, abduction), knee (flexion, extension), and ankle (plantarflexion, inversion) during FW than SW. CONCLUSIONS Overweight children experienced increased joint moments, which can have long-term orthopedic implications and suggest a need for more nonweight-bearing activities within exercise prescription. The percent of increase in joint moments from SW to FW was not different for overweight and normal-weight children. These findings can be used in developing an exercise prescription that must involve weight-bearing activity.

Reliability of plantar pressure platforms

Plantar pressure measurement is common practice in many research and clinical protocols. While the accuracy of some plantar pressure measuring devices and methods for ensuring consistency in data collection on plantar pressure measuring devices have been reported, the reliability of different devices when testing the same individuals is not known. This study calculated intra-mat, intra-manufacturer, and inter-manufacturer reliability of plantar pressure parameters as well as the number of plantar pressure trials needed to reach a stable estimate of the mean for an individual. Twenty-two healthy adults completed ten walking trials across each of two Novel emed-x(®) and two Tekscan MatScan(®) plantar pressure measuring devices in a single visit. Intraclass correlation (ICC) was used to describe the agreement between values measured by different devices. All intra-platform reliability correlations were greater than 0.70. All inter-emed-x(®) reliability correlations were greater than 0.70. Inter-MatScan(®) reliability correlations were greater than 0.70 in 31 and 52 of 56 parameters when looking at a 10-trial average and a 5-trial average, respectively. Inter-manufacturer reliability including all four devices was greater than 0.70 for 52 and 56 of 56 parameters when looking at a 10-trial average and a 5-trial average, respectively. All parameters reached a value within 90% of an unbiased estimate of the mean within five trials. Overall, reliability results are encouraging for investigators and clinicians who may have plantar pressure data sets that include data collected on different devices.

The effect of foot structure on 1st metatarsophalangeal joint flexibility and hallucal loading.

The purpose of our study was to examine 1st metatarsophalangeal (MTP) joint motion and flexibility and plantar loads in individuals with high, normal and low arch foot structures. Asymptomatic individuals (n=61), with high, normal and low arches participated in this study. Foot structure was quantified using malleolar valgus index (MVI) and arch height index (AHI). First MTP joint flexibility was measured using a specially constructed jig. Peak pressure under the hallux, 1st and 2nd metatarsals during walking was assessed using a pedobarograph. A one-way ANOVA with Bonferroni-adjusted post hoc comparisons was used to assess between-group differences in MVI, AHI, early and late 1st MTP joint flexibility in sitting and standing, peak dorsiflexion (DF), and peak pressure under the hallux, 1st and 2nd metatarsals. Stepwise linear regression was used to identify predictors of hallucal loading. Significant between-group differences were found in MVI (F(2,56)=15.4, p<0.01), 1st MTP late flexibility in sitting (F(2,57)=3.7, p=0.03), and standing (F(2,57)=3.7, p=0.03). Post hoc comparisons demonstrated that 1st MTP late flexibility in sitting was significantly higher in individuals with low arch compared to high arch structure, and that 1st MTP late flexibility in standing was significantly higher in individuals with low arch compared to normal arch structure. Stepwise regression analysis indicated that MVI and 1st MTP joint early flexibility in sitting explain about 20% of the variance in hallucal peak pressure. Our results provide objective evidence indicating that individuals with low arches show increased 1st MTP joint late flexibility compared to individuals with normal arch structure, and that hindfoot alignment and 1st MTP joint flexibility affect hallucal loading.

Wound measurement by curvature maps: a feasibility study

A non-contact wound measurement method by laser scanner and curvature maps is presented. A patients foot ulcer is scanned by FastSCAN ten times over a three-week period. With the surfaces 3D coordinates, curvature maps of the ulcerous area are calculated. Utilizing a specified rim curvature value, the wound edge is detected and processed via cubic spline smoothing, which is qualitatively verified by a photograph. Subsequently, the depth, area and volume of the wound can be calculated. The results indicate that laser scanning followed by curvature analysis might be a potential clinical tool for non-contact measurement of wounds.

Consequences of pediatric obesity on the foot and ankle complex.

BACKGROUND Anthropometric status can influence gait biomechanics, but there is relatively little published research regarding foot and ankle characteristics in the obese pediatric population. We sought to compare the structural and functional characteristics of the foot and ankle complex in obese and non-obese children. METHODS Twenty healthy children (ten obese and ten normal weight) were recruited for a cross-sectional research study. Anthropometric parameters were measured to evaluate active ankle dorsiflexion, arch height (arch height index, arch rigidity index ratio, and arch drop), foot alignment (resting calcaneal stance position and forefoot-rearfoot alignment in unloaded and loaded positions), and foot type (malleolar valgus index). Independent t tests determined significant differences between groups for all assessed parameters. Statistical significance was set at P < .0125. RESULTS Compared with non-obese participants, obese participants had significantly greater arch drop (mean ± SD: 5.10 ± 2.13 mm versus 2.90 ± 1.20 mm; P =.011) and a trend toward lower arch rigidity index ratios (mean ± SD: 0.92 ± 0.03 versus 0.95 ± 0.02; P = .013). In addition, obese participants had significantly less active ankle dorsiflexion at 90° of knee flexion versus non-obese participants (mean ± SD: 19.57 ± 5.17 versus 29.07 ± 3.06; P < .001). No significant differences existed between groups for any other anthropometric measurements. CONCLUSIONS The decreased active ankle dorsiflexion in the obese group can increase foot contact for a longer period of the stance phase of gait. Obese participants also presented with a more flexible foot when bearing weight.

Effects of weight loss on foot structure and function in obese adults: A pilot randomized controlled trial

OBJECTIVE To investigate the effects of weight reduction on foot structure, gait, and dynamic plantar loading in obese adults. DESIGN In a 3-month randomized-controlled trial, participants were randomized to receive either a weight loss intervention based on portion-controlled meals or a delayed-treatment control. PARTICIPANTS 41 adults (32 F, 9 M) with a mean ± SD age of 56.2 ± 4.7 years and a BMI of 35.9 ± 4.2 kg/m(2). MEASUREMENTS Arch Height Index (AHI), Malleolar Valgus Index (MVI), spatial and temporal gait parameters, plantar peak pressure (PP) and weight were measured at baseline, 3, and 6 months. RESULTS The intervention group experienced significantly greater weight loss than did the control group (5.9 ± 4.0 kg versus 1.9 ± 3.2 kg, p = 0.001) after 3 months. There were no differences between the groups in anatomical foot structure or gait. However, the treatment group showed a significantly reduced PP than the control group beneath the lateral arch and the metatarsals 4 (all p values < .05) at 3 months. The change in PP correlated significantly with the change in weight at the metatarsal 2 (r = 0.57, p = 0.0219), metatarsal 3 (r = 0.56, p = 0.0064) and the medial arch (r = 0.26, p < 0.0001) at 6 months. CONCLUSION This was the first RCT designed to assess the effects of weight loss on foot structure, gait, and plantar loading in obese adults. Even a modest weight loss significantly reduced the dynamic plantar loading in obese adults. However, weight loss appeared to have no effects on foot structure and gait.