Effect of shoe modifications on center of pressure and in-shoe plantar pressures

Foot Function, Foot Pain, and Falls in Older Adults: The Framingham Foot Study

BACKGROUND

Although foot pain has been linked to fall risk, contributions of pain severity, foot posture, or foot function are unclear. These factors were examined in a cohort of older adults.

OBJECTIVE

The purpose of this study was to examine the associations of foot pain, severity of foot pain, and measures of foot posture and dynamic foot function with reported falls in a large, well-described cohort of older adults from the Framingham Foot Study.

METHODS

Foot pain, posture, and function were collected from Framingham Foot Study participants who were queried about falls over the past year (0, 1, and ≥2 falls). Logistic regression was used to calculate odds ratios (ORs) and 95% confidence intervals (CIs) for the relation of falls with foot pain, pain severity, foot posture, and foot function adjusting for covariates.

RESULTS

The mean age of the 1,375 participants was 69 years; 57% were female, and 21% reported foot pain (40% mild pain, 47% moderate pain, and 13% severe pain). One-third reported falls in the past year (1 fall: n = 263, ≥2 falls: n = 152). Foot pain was associated with a 62% increased odds of recurrent falls. Those with moderate and severe foot pain showed increased odds of ≥2 falls (OR 1.78, CI 1.06-2.99, and OR 3.25, CI 1.65-7.48, respectively) compared to those with no foot pain. Foot function was not associated with falls. Compared to normal foot posture, those with planus foot posture had 78% higher odds of ≥2 falls.

CONCLUSION

Higher odds of recurrent falls were observed in individuals with foot pain, especially severe foot pain, as well as in individuals with planus foot posture, indicating that both foot pain and foot posture may play a role in increasing the risk of falls among older adults.

Ergonomic footwear for Sri Lankan primary schoolchildren: A review of the literature

BACKGROUND

Foot ailments are common among schoolchildren, some of which may be attributed to wearing ill-fitting footwear. As schoolchildren often participate in athletic activity, they are doubly vulnerable to foot ailments, and are particularly vulnerable to conditions such as hallux valgus, Achilles tendonitis, athlete's foot, corns and calluses. Thus, there is an acute need for the design and manufacture of ergonomic footwear for this target group. While research on appropriate footwear for children has been carried out in relation to child populations in other societies, research on the circumstances of Sri Lankan schoolchildren is lacking. Neither the requisite design know-how nor the information for design is available to footwear manufacturers.

OBJECTIVES

This review of the literature is aimed at confirming the need for ergonomic footwear from the point of view of the effects of wearing ill-fitting shoes and at identifying the requirements in terms of design information, especially for schoolchildren of the age group five to ten years, to empower footwear manufacturers.

METHODS

PubMed, Google scholar and Science Direct were used for the literature search.

RESULTS

208 publications were read in full, 94 of which are referenced in this review.

CONCLUSION

The review shows morphological measurements, behavior and activity patterns of schoolchildren and environmental conditions they are exposed to should be determined to formulate design information.

Influence of heel design in an orthopedic shoe on ground reaction forces during walking

BACKGROUND

One of the treatments prescribed for musculoskeletal patients is orthopedic shoe. The use of an orthopedic shoe is thought to produce a more typical ground reactive force pattern.

OBJECTIVES

This study was designed to determine the influence of three heel designs of an orthopedic shoe on the ground reaction forces during walking in healthy subjects.

STUDY DESIGN

Quasi-experimental.

METHOD

In total, 30 healthy adults (12 males, 18 females) walked at a self-selected pace for six trials in each of the three shoe conditions having three different heels which included the following: standard heel, beveled heel, and positive posterior heel flare. For each trial, ground reaction force parameters were recorded using a force plate.

RESULTS

Repeated measures analysis of variance indicated that the impact force was significantly reduced for the positive posterior heel flare condition by 8% and 13% compared with standard and beveled heels, respectively (p < 0.001). The first peak of vertical force showed a significant reduction in the beveled heel by 5% and 4% compared with the standard heel and the positive posterior heel flare, respectively (p < 0.001). Loading rate was significantly reduced in the beveled heel and the positive posterior heel flare conditions (p < 0.05).

CONCLUSION

Positive posterior heel flare reduced impact force due to its geometry flexibility, while a beveled heel reduced first peak of vertical force. The findings of this study show that the shape of the heel therefore has the potential to modify impact loads during walking.

CLINICAL RELEVANCE

This study provides new evidence that by changing shape in the heel of orthopedic shoe impact loads are reduced during walking. Thus, these findings indicate that use of heel design may be beneficial for various musculoskeletal disorders, including key public health problems.

The role of shoe design on the prediction of free torque at the shoe-surface interface using pressure insole technology

The goal of the current study was to expand on previous work to validate the use of pressure insole technology in conjunction with linear regression models to predict the free torque at the shoe-surface interface that is generated while wearing different athletic shoes. Three distinctly different shoe designs were utilised. The stiffness of each shoe was determined with a material's testing machine. Six participants wore each shoe that was fitted with an insole pressure measurement device and performed rotation trials on an embedded force plate. A pressure sensor mask was constructed from those sensors having a high linear correlation with free torque values. Linear regression models were developed to predict free torques from these pressure sensor data. The models were able to accurately predict their own free torque well (RMS error 3.72 ± 0.74 Nm), but not that of the other shoes (RMS error 10.43 ± 3.79 Nm). Models performing self-prediction were also able to measure differences in shoe stiffness. The results of the current study showed the need for participant-shoe specific linear regression models to insure high prediction accuracy of free torques from pressure sensor data during isolated internal and external rotations of the body with respect to a planted foot.

Foot Pain and Pronated Foot Type Are Associated with Self-Reported Mobility Limitations in Older Adults: The Framingham Foot Study

BACKGROUND

The foot plays an important role in supporting the body when undertaking weight-bearing activities. Aging is associated with an increased prevalence of foot pain and a lowering of the arch of the foot, both of which may impair mobility.

OBJECTIVE

To examine the associations of foot pain, foot posture and dynamic foot function with self-reported mobility limitations in community-dwelling older adults.

METHODS

Foot examinations were conducted on 1,860 members of the Framingham Study in 2002-2005. Foot posture was categorized as normal, planus or cavus using static pressure measurements, and foot function was categorized as normal, pronated or supinated using dynamic pressure measurements. Participants were asked whether they had foot pain and any difficulty performing a list of eight weight-bearing tasks. Multivariate logistic regression and linear regression models were used to examine the associations of foot pain, posture, function and ability to perform these activities.

RESULTS

After adjusting for age, sex, height and weight, foot pain was significantly associated with difficulty performing all eight weight-bearing activities. Compared to those with normal foot posture and function, participants with planus foot posture were more likely to report difficulty remaining balanced [odds ratio (OR) = 1.40, 95% confidence interval (CI) 1.06-1.85; p = 0.018] and individuals with pronated foot function were more likely to report difficulty walking across a small room (OR = 2.07, 95% CI 1.02-4.22; p = 0.045). Foot pain and planus foot posture were associated with an overall mobility limitation score combining performances on each measure.

CONCLUSION

Foot pain, planus foot posture and pronated foot function are associated with self-reported difficulty undertaking common weight-bearing tasks. Interventions to reduce foot pain and improve foot posture and function may therefore have a role in improving mobility in older adults.

The efficacy of foot orthoses on alteration to center of pressure displacement in subjects with flat and normal feet: a literature review

PURPOSE

The aim of this review was to evaluate and compare the effect of foot orthoses on center of pressure (CoP) displacement in healthy patients and those with flat foot.

METHOD

The search strategy was based on the Population Intervention Comparison Outcome (PICO) method. A search was performed in PubMed, Science Direct, Google scholar and ISI web of knowledge databases by using selected keywords. Seventeen articles were selected for final evaluation. The procedure was followed using the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) method.

RESULT

The results of the literature review demonstrated that there is lack of evidence to show that FOs improve CoP displacement in subjects with flat foot.

CONCLUSION

There is no consistent evidence to prove the efficacy of FOs on altering CoP displacement in healthy subjects but in those with flat foot, FOs decreased CoP excursion. Implications for Rehabilitation Foot orthoses (FOs) have become an integral part of the treatment of injuries of the foot, ankle, and lower extremity. Assessment of FOs effect on the COP displacement can help to provide a better understanding of the body's compensatory mechanisms and their therapeutic effects. There is no consistent evidence to prove the efficacy of FOs on CoP displacement in healthy subjects but in flat foot subjects foot orthoses decreased CoP excursion has been demonstrated.

Foot center of pressure trajectory alteration by biomechanical manipulation of shoe design

BACKGROUND

Footwear-generated biomechanical manipulations have been shown to alter lower limb kinetics. It has been suggested that this is due to altered trajectory of the foot's center of pressure (COP), conveying a shift in location of the ground reaction force and modifying moments and forces acting on proximal body segments. However, past studies have focused on qualitative association between footwear design and the COP locus. Moreover, this association was calculated via indirect analysis. The purpose of the present study was to directly examine and quantify the correlation between measured footwear biomechanical manipulation and the location of the COP trajectory during gait.

METHODS

A novel biomechanical device allowing flexible positioning of 2 convex-shaped elements attached to its sole was utilized. A total of 20 healthy male adults underwent direct in-shoe pressure measurements while walking with the device set at 7 mediolateral configurations. COP data were collected during gait and analyzed with respect to different stance subphases.

RESULTS

COP location significantly correlated with a shift of the elements medially or laterally. The linear model describing this correlation was found to be statistically significant.

CONCLUSION

There was significant correlation between the plantar orientation of the shoe device configuration and the COP.

CLINICAL RELEVANCE

Changes in COP trajectory may be valuable in patients suffering from multiple foot disorders elevating pressure on the foot. Accurate COP control could aid in the manipulation of the forces acting on the proximal joints during gait. In addition, these findings may have implications in the field of biomechanical apparatus design and practice.

Apparent mass distribution at the feet of standing subjects exposed to whole-body vibration

This study was carried out to investigate the influence of the body posture and of the foot support on the apparent mass distribution at the feet of standing subjects exposed to whole-body vibration. The apparent mass was measured at the driving point through a capacitive pressure sensor matrix, which allowed to separate the contributions of the different foot regions. The overall value was also determined using a conventional measurement system based on piezoelectric load cells. Ten male subjects performed 15 tests with three kinds of feet supports (flat rigid, anatomic rigid and flat soft) in five different postures. Static components of the pressure measurements were exploited to identify which fraction of the weight is supported by the rearfoot, the midfoot and the forefoot in the various test configurations. Factorial design of experiments on different response variables showed that the apparent mass is affected by the posture but not by the type of feet contact surface; conversely, the presence of insoles varies with the apparent mass distribution on the different feet parts.

PRACTITIONER SUMMARY

The response of standing subjects to whole-body vibration has always been considered as a global parameter measured at the driving point, neglecting the local phenomena occurring in different foot parts. We have experimentally identified the apparent mass distribution of subjects in different standing postures and with different foot supports.

Immediate effects of contralateral and ipsilateral cane use on normal adult gait

OBJECTIVE

To determine the effects of ipsilateral and contralateral cane use on gait kinematics and peak vertical force in young healthy adults.

DESIGN

Prospective observational study.

SETTING

Veterans Affairs Healthcare Center.

PARTICIPANTS

Fifteen healthy adults of aged 26 to 52 years (mean age 31 years) with no gait impairment and minimal experience using single-point canes.

METHODS

The Pedar-X Mobile System plantar pressure measurement system was used to collect kinematic data from subjects walking in 3 different conditions (relative to a randomly "assigned" limb): contralateral cane (C), ipsilateral cane (I), and no cane (N).

MAIN OUTCOME MEASURES

Peak vertical force, cadence, percentage swing phase and double limb support, and regional plantar pressure ratios.

RESULTS

Peak vertical force (normalized for body weight) was reduced during both cane use conditions on the randomly assigned limb when compared to walking unaided (P<.001). The peak vertical force was 7% to 11% lower for the assigned limb than the opposite limb when a cane was used on either side (P<.016). Mean cadence was higher when participants ambulated without a cane (113 steps/min) than with a cane used on either the contralateral (98 steps/min) or ipsilateral (98 steps/min) side (P<.0001). Mean cadence did not significantly differ between the cane use conditions (P=.93). Regional plantar pressure ratios did not significantly change on either limb in any of the tested conditions. Double limb support slightly increased with cane use (P<.016).

CONCLUSION

Both ipsilateral and contralateral cane use reduced cadence and mean peak vertical plantar force on the limb advanced with the cane in healthy young adults. Double limb support increased with cane use likely due to the reduced cadence and initial unfamiliarity with using an assistive device. A clinical implication of these findings is that prescription of canes for either ipsilateral or contralateral use effectively offloads a designated lower limb.

Biomechanics of the double rocker sole shoe: gait kinematics and kinetics

The use of footwear with contoured soles is common in treatment and care of patients with diabetes; these rocker sole shoes are designed to alleviate loading in key areas on the plantar surface of the foot, reducing pressure in key areas and alleviating pain, and potential soft tissue damage. While investigations of pressure changes have been conducted, no quantitative study to date has addressed the three-dimensional (3D) kinematic and kinetic changes that result from using these shoes. Forty subjects were tested wearing both unmodified and double rocker sole shoes, and the resulting motion patterns were compared to assess change caused by the rocker sole. Overall walking speed remained unchanged throughout testing; slightly increased flexion (<5 degrees ) was apparent at the hip, knee, and ankle during early and mid-stance. These results demonstrate the maintenance of gait function with minimal kinematic changes when using the rocker sole shoe. Investigations of multisegmental foot motion may reveal additional information about the contour effects; analysis of contour variations may also be warranted to investigate the possibility of controlling motion based on rocker sole parameters.

Biomechanics of the double rocker sole shoe: gait kinematics and kinetics

This paper reports the kinematic and kinetic changes in gait with bilateral double rocker sole shoe modifications. Three-dimensional motion analysis techniques were used to evaluate gait characteristics (temporal-spatial, kinematic, and kinetic measures) of forty (40) subjects while wearing baseline and double rocker sole shoes. Walking speed was unchanged by the double rocker modification. Sagittal plane motions showed significant change at the pelvis, hip, knee, and ankle. (p = 0.01). The toe-only rocker consistently resulted in increase in posterior pelvic tilt (p =0.01). Kinetic changes were observed at the hip in the sagittal and transverse planes, and at the knee and ankle in the sagittal planes. Changes in pelvic tilt and hip rotation were hypothesized to result from feelings of imbalance during ambulation with the double rocker sole shoe.

Biomechanical implications of the negative heel rocker sole shoe: gait kinematics and kinetics

Rocker sole shoes are commonly prescribed to diabetic patients with insensate feet. Recent passage of the therapeutic shoe bill has drawn an increased focus to prescription rehabilitative footwear. The purpose of this work is to investigate the dynamics of lower extremity joints (hip, knee and ankle) with the application of a negative heel rocker sole shoe under controlled lab conditions. Forty normal adults volunteered for gait evaluations using controlled baseline and prescription negative heel rocker sole shoes. Three-dimensional motion analysis techniques were used to acquire kinematic and kinetic data using a six-camera Vicon 370 motion system and two AMTI force plates. No significant change in walking speed or stride length was seen with the negative heel rocker shoe, although cadence was increased. The most significant kinematic changes with the application of the negative heel shoe occurred at the ankle in the sagittal plane with increased plantarflexion at terminal stance. Significant hip and knee changes were also noted with increased mid-stance hip extension and knee flexion. The most significant kinetic effects were seen in the transverse plane followed by changes in the sagittal and coronal planes. Changes in power were mostly noted in the sagittal plane. Other statistically significant changes in gait kinematics and kinetics were observed, although the magnitudes and durations were limited and as a result were not considered clinically significant. The study results indicated the negative heel rocker shoe significantly altered proximal joint metrics (hip and knee). The most significant distal joint alterations were seen in sagittal plane ankle kinetics. These kinematic and kinetic changes, along with previously studied effects of pressure relief at the metatarsal heads, should aid medical professionals in prescribing prophylactic footwear.

Clinical determinants of plantar forces and pressures during walking in older people

The aim of this study was to determine the extent to which clinical tests of structural characteristics of the foot and ankle could account for variation in the magnitude of regional forces and pressures under the foot during walking in older people. Plantar forces and pressures were obtained from 172 older people (53 men, 119 women) aged 62-96 years (mean 80.0, S.D. 6.4) using a floor-mounted resistive sensor mat system. Subjects also completed tests of foot posture, range of motion, strength, sensation and toe deformity. Multiple regression analysis was then used to determine which clinical variables were most strongly correlated with plantar forces and pressures. Maximum forces and peak pressures under most regions of the foot were largely explained by differences in bodyweight, with some important exceptions. Loading under the midfoot was associated with the arch index, loading under the first metatarsophalangeal joint (1st MPJ) was associated with 1st MPJ range of motion, and loading under the hallux was associated with hallux plantarflexor strength, 1st MPJ range of motion and the degree of hallux valgus deformity. Clinical measurements accounted for 13-53% of the variance in maximum force and 4-40% of the variance in peak pressures. These findings indicate that structural foot and ankle characteristics identified from clinical measurements can explain some key aspects of plantar loading patterns of the foot. This information provides further insights into the dynamic function of the foot, which might assist in the development of interventions for pressure-related foot complaints in older people.

Effects of the toe-only rocker on gait kinematics and kinetics in able-bodied persons

Rocker sole shoes are commonly prescribed to diabetic patients with insensate feet. Recent passage of the therapeutic shoe bill has drawn an increased focus on prescription of rehabilitative footwear. The purpose of this work is to investigate the dynamics of lower extremity joints (hip, knee, and ankle) with the application of a toe-only rocker sole shoe under controlled laboratory conditions. Forty (40) normal adults volunteered for gait analysis using controlled baseline and prescription toe-only rocker sole shoes. Three-dimensional motion analysis techniques were used to acquire kinematic and kinetic data using a six camera Vicon 370 motion system and two AMTI force plates. While significant changes from baseline to toe-only rocker were noted in cadence (increased) and stride length (decreased), no significant change in walking speed was observed. The most significant kinematic changes with the application of the toe-only shoe occurred at the ankle and knee in the sagittal plane during stance. The most significant kinetic effects were observed in the hip and knee during swing phase. Changes in power were noted at all joints, mostly in terminal stance. These kinematic and kinetic changes, along with previously studied effects of pressure relief at the metatarsal heads, should aid medical professionals in prescribing prophylactic footwear.

Temporal changes in postural sway caused by ultrashort-acting hypnotics: triazolam and zolpidem

Two ultrashort-acting hypnotics, triazolam 0.25 mg and zolpidem 10 mg, were studied for their effects on equilibrium function in humans. Eight healthy male subjects participated in a double-blind, placebo-controlled study after informed consent. They subjected to static equilibrium tests, oculomotor tests and an assay of drug concentrations in the blood. Zolpidem was statistically significant in postural sway in tandem stance test, as defined by parametric values of tracing sum length and polygonal area of foot pressure center measured by a gait analysis system. In the tandem stance test, triazolam was statistically significant in postural sway only as defined by the polygonal area. However, in the Romberg test, the only statistically significant difference in zolpidem use was observed in polygonal area values. Blood concentrations of triazolam and zolpidem were found to closely correlate with the extent of postural sway in both tandem stance and Romberg tests. In this study, zolpidem with minimal muscle-relaxant effect incurred imbalance more extensively than triazolam, which is known for its effect of muscle relaxation. In addition, gaze deviation nystagmus was observed only in zolpidem use in 5 of 8 subjects (62.5%). From these results, it is suggested that in the use of hypnotics, sway derives from the suppression of the central nervous system relevant to awakening rather than from muscle relaxation. The prior reference to blood concentrations of hypnotics should help improve safety care in minimizing loss of balance control and possible fall.

Evaluation of Rocker Sole by Pressure???Time Curves in Insensate Forefoot During Gait

OBJECTIVE

The rocker sole reduces plantar pressure in the insensate forefoot during gait, but the reasons have remained unclear. This study aimed to derive new variables descriptive of the effects of the rocker sole.

DESIGN

We measured plantar pressures in eight forefoot areas in the insensate feet of ten diabetic subjects and performed stepwise regression of pressures as cubic functions of time in patients wearing shoes without and with prefabricated rocker soles.

RESULTS

Pressure-time curves were all sigmoid in shape, but inflected at different time points, and were regressed by different variables in different forefoot areas in shoes without rocker soles. The rocker sole reduced peak pressures and pressure-time integrals and made pressure-time curves more concave. Inflections occurred at 15% or 16% of the gait cycle time and reached peak pressure later with the rocker. The more anterior the forefoot areas, the more concave their curves and the greater their regression parameters became.

CONCLUSIONS

To evaluate the effectiveness of a rocker sole, physiatrists may regress sigmoid pressure-time curves as cubic functions of time in the insensate forefoot, check simultaneous inflections of the curves in areas rotated by the rocker sole, and compare their concavity and regression parameters in areas rotated at different distances from the axis of rotation. By doing so, physiatrists may be better able to improve the design of rocker sole and other forms of forefoot orthoses.

Changes of Joint Moments in the Gait of Normal Subjects Wearing Laterally Wedged Insoles

OBJECTIVE

The purpose of this study was to assess the kinematic and kinetic effects of wearing a laterally wedged insole on the knee joint moment during gait, specifically in the frontal plane, in normal healthy adults.

DESIGN

Motion analyses were conducted with (1) a three-dimensional motion analysis system and (2) ground reaction force analysis using force platforms when subjects walked under three different insole conditions: no wedge, a low wedge with a 3-degree lateral angle, and a high wedge with a 6-degree lateral angle.

RESULTS

The high-wedge insole significantly reduced the knee joint varus moment during gait compared with the gait with the no-wedge insole. The actual segment angles at the subtalar and knee joints did not show any changes due to insole conditions. In contrast, the subtalar joint valgus moment increased for the high-wedge insole. This finding was correlated with a greater moment arm of the subtalar joint valgus moment with the high-wedge insole.

CONCLUSIONS

These results indicate that, under dynamic conditions, the subjects wearing laterally wedged insoles had both changes of moments at the subtalar and knee joints via the more laterally shifted location of the center of pressure.

An in vitro study of individual ankle muscle actions on the center of pressure

The objective of this study was to correlate the effects of muscle force on the movement of the center of pressure (COP) for increased clinical utility of the COP measurement. Five fresh frozen cadaveric specimens were used to apply a 49 N sinusoidal muscle force to isolated or grouped extrinsic ankle muscles, and a constant ankle joint reaction force at different tibial positions. The muscle force and the vertical ground reaction force (GRF) play the role of a mechanical lever system so that the differential COP movement can be interpreted as a moment arm for the vertical GRF.

Walking strategy in diabetic patients with peripheral neuropathy

OBJECTIVE

Diabetic neuropathic patients show a peculiar loading pattern of the foot, which led us to hypothesize that a substantial modification exists in their deambulatory strategy. The aim of the present study was to support this hypothesis by quantifying the changes of the loading patterns and by monitoring the excursion of center of pressure (COP) during gait.

RESEARCH DESIGN AND METHODS

-A total of 21 healthy volunteers (C) and 61 diabetic patients were evaluated: 27 diabetic subjects without neuropathy (D), 19 with neuropathy (DN), and 15 with previous neuropathic ulcer (DPU). A piezo-dynamometric platform was used to record the foot-to-floor interaction by measuring loading time and the instantaneous COP position during the stance phase of gait.

RESULTS

Loading time was significantly longer in neuropathic patients than in control subjects (DPU: 816.8 +/- 150 ms; DN: 828.6 +/- 152 ms; D: 766.5 +/- 89.9 ms; C: 723.7 +/- 65.7 ms; P < 0.05). COP excursion along the medio-lateral axis of the foot clearly decreased from C to DPU groups (C: 6.41 +/- 0.1 cm; D: 4.88 +/- 0.2 cm; DN: 4.57 +/- 0.1 cm; DPU: 3.36 +/- 0.1 cm; P < 0.05) as well as COP excursion along the longitudinal axis for the DPU group only (C: 26.6 +/- 1 cm; D: 26.9 +/- 1 cm; DN: 27.2 +/- 1 cm; DPU: 24.2 +/- 1 cm; P < 0.05). COP integrals were significantly reduced for all pathological classes (DPU: 14.2 +/- 8 cm(2); DN: 25.8 +/- 6 cm(2); D: 27.7 +/- 3 cm(2); C: 38.6 +/- 6 cm(2); P < 0.05).

CONCLUSIONS

The accurate quantification of loading patterns and of COP excursions and integrals highlights changes of foot-to-floor interaction in diabetic neuropathic patients. The decreased medio-lateral and longitudinal COP excursions and corresponding changes of loading times and patterns support our hypothesis that a change in the walking strategy of diabetic patients with peripheral neuropathy does occur.