An investigation into plantar pressure measurement protocols for footwear research

Influence of circumferential ankle pressure of shoe collar on the kinematics, dynamic stability, electromyography, and plantar pressure during normal walking

BACKGROUND

The shoe's collar plays a significant role in supporting the ankle during walking. Since the protective effect of the collar requires the circular embracing of the ankle and shank, a stiffer collar might be involved with increased circumferential ankle pressure (CAP). It is not clear how collar CAP affects walking performance. Therefore, this study was aimed at examining the influence of the collar CAP on the kinematics, dynamic stability, electromyography (EMG), and plantar pressure during normal walking.

METHOD

Sixteen healthy male participants walked on a treadmill while wearing a custom-designed high-collar shoe with 10 (low), 30 (medium), and 60 mmHg (high) CAP conditions, and the joint angles, dynamic stability index, EMG, and plantar pressure were measured.

RESULT

While the low CAP condition did not affect the ankle range of motion (ROM), The high CAP condition restricted both the ankle sagittal and frontal ROM, whereas the medium CAP condition limited only the ankle frontal ROM. The knee and hip ROM did not differ between conditions. The dynamic stability for the high and medium CAP cases was comparable but significantly higher than that of the low CAP condition. The ankle muscle activity and corresponding co-contraction increased with increasing CAP for gastrocnemius medialis (GM), soleus (SOL), peroneus longus (PL), tibialis anterior (TA) muscles in the weight acceptance and push-off phases but not in the single limb support. Knee muscle activity, including vastus lateralis (VL) and semitendinosus (SEMI) was similar between all conditions. A higher relative pressure was observed under the lateral aspect of the heel when walking in the high CAP condition.

CONCLUSION

The results suggest that a high-collar shoe with a high CAP may not be an appropriate choice for walking owing to the injury risk factors and limited walking efficiency. A medium CAP is associated with certain advantages and, thus, a superior choice for high-collar shoe design.

The influence of partial weight bearing on plantar peak forces using three different types of postoperative shoes

BACKGROUND

Therapeutic shoes and partial weight bearing regimes are used after foot surgery to prevent the operated region from excessive load. It remains unclear to which extent partial weight bearing reduces the plantar peak forces. Therefore, we investigated the correlation of weight bearing and plantar peak forces in commonly used therapeutic shoes.

METHODS

Three different weight bearing regimes (20 kg, 40 kg, full weight) were investigated in 20 healthy volunteers. Sensor insoles were used to measure peak forces of the forefoot, midfoot, heel and the complete foot using four kind of shoes (bandage shoe, forefoot relief shoe, short walker and standard sneaker). Peak forces were compared between shoes using one-way ANOVA. The influence of partial weight bearing relative to the peak forces was examined by linear regression analysis.

RESULTS

All therapeutic shoes reduced significantly peak forces of the fore- and midfoot when compared to the reference shoe; the largest reduction was achieved by the forefoot relief shoe (-70 % at forefoot). Weight load and the resulting peak force showed a positive linear correlation for all regions and shoe types. Partial weight bearing significantly reduced the forefoot's force ratio compared to full weight bearing for all shoes except the forefoot relief shoe.

CONCLUSIONS

Partial weight bearing is a strong instrument to reduce plantar peak forces of the forefoot, additionally to the proven offloading effect of therapeutic shoes.

Pressure Properties of Three Different Types of Prefabricated Insoles Related to Plantar Pressure in Asymptomatic Men

BACKGROUND

In clinical fields, many types of insoles are used to not only realign movement patterns, but also treat pressure-related foot diseases. However, the characteristics of and plantar pressure in each type of insole are still unclear. Therefore, the aim of this study was to validate the plantar pressure-relieving effect of three representative types of insoles (metatarsal padding insole [MPI], lateral heel wedge insole [LHI], and arch support insole [ASI]) in asymptomatic men.

METHODS

A total of 35 feet of 35 asymptomatic men with a mean age of 23.4 ± 2.0 years were included. Pedobarographic data were evaluated by dividing the foot into eight designated regions to compare the three types of insoles. Peak plantar pressure (PPP) and pressure time integral (PTI) were assessed using the Pedar-X system. A repeated measures analysis of variance was used for statistical analyses.

RESULTS

In the hallux region, there was no statistically significant difference. MPI showed highest pressure in the 2nd-5th toe and midfoot region, but lowest in the central and lateral forefoot regions. Meanwhile, ASI showed highest pressure in the medial forefoot region but lowest in the lateral heel region. Lastly, pressure in the lateral heel region was highest in LHI. Overall, results of PTI were similar to those of PPP.

CONCLUSIONS

This study demonstrated that the three types of insole each could reduce and redistribute pressure of specific part of the foot to help select an appropriate insole for each purpose.

Change of In-Shoe Plantar Pressure According to Types of Shoes (Flat Shoes, Running Shoes, and High Heels)

Background

The type of footwear is one of several factors that affect foot pressure. Despite its usefulness in identifying pathology and preventing and treating foot-related diseases, the type of shoes has been investigated and compared in only a few studies. This study aimed to investigate differences in plantar pressure, induced by flat, running, and high-heeled shoes in healthy, young women.

Methods

A total of 27 healthy women (27 feet) with a mean age of 21.5 ± 2.03 years were included in this study. Based on demographic data, radiologic measurements, clinical scores, temporal gait parameters, and kinematic parameters of gait, we confirmed the participants had normal feet. Then, pedobarographic data were measured by dividing each foot into seven regions to compare the three types of shoes. Peak plantar pressure and pressure-time integral were calculated using the Pedar-X system. The one-way analysis of variance and the Kruskal-Wallis test with Mann Whitney U-test were used for statistical analyses.

Results

Regarding the 7 regions of the foot, flat shoes resulted in a significantly higher pressure than running shoes in the hallux and lesser toes and the highest pressure in the metatarsal head (MTH) 3-5 and the hindfoot. In contrast, in the MTH 1 and MTH 2 regions, the high-heeled shoes had the highest measured pressure, followed by the flat shoes. Lastly, there was no high pressure in running shoes in any region except for the midfoot compared to the other shoes.

Conclusions

It can be inferred from our findings that flat and high-heeled shoes can generate a considerable burden on specific parts of the foot, which will aid in choosing appropriate shoes. Also, wearing running shoes places less burden on the overall foot.

Systematic reduction of leg muscle activity throughout a standard assessment of running footwear

PURPOSE

This study aimed to investigate whether there is a systematic change of leg muscle activity, as quantified by surface electromyography (EMG), throughout a standard running footwear assessment protocol at a predetermined running speed.

METHODS

Thirty-one physically active adults (15 females and 16 males) completed 5 testing rounds consisting of overground running trials at a speed of 3.5 m/s. The level of muscle activity from 6 major leg muscles was recorded using surface EMG. The variables assessed were the EMG total intensity as a function of time and the cumulative EMG overall intensity. Systematic effects of the chronological testing round (independent variable) on the normalized EMG overall intensity (dependent variable) were examined using Friedman analysis of variates and post hoc pairwise Wilcoxon signed-rank tests (α = 0.05).

RESULTS

There was a systematic reduction in overall EMG intensity for all 6 muscles over the time course of the running protocol (p < 0.001) until the fourth testing round when EMG intensities reached a steady state. The one exception was the biceps femoris muscle, which showed a significant reduction of EMG intensity during the stance phase (p < 0.001) but not the swing phase (p = 0.16).

CONCLUSION

While running at a predetermined speed, the neuromuscular system undergoes an adaptation process characterized by a progressive reduction in the activity level of major leg muscles. This process may represent an optimization strategy of the neuromuscular system towards a more energetically efficient running style. Future running protocols should include a familiarization period of at least 7 min or 600 strides of running at the predetermined speed.

RELIABILITY OF WIRELESS INSOLE BAROPODOMETRY OF NORMAL INDIVIDUAL'S GAIT

Objective:

The plantar pressure distribution can be assessed quantitatively by computerized baropodometry such as carpet or insole. An insole-type system with wireless transmission was developed and plantar pressure results were previously validated by force platform. However, the reproducibility of the system had not been determined. Our objective was to evaluate the reliability of the results in different gait cycles, clinical characteristics and in different plantar anatomical sites.

Methods:

41 healthy adults (age, 34 ± 13 years; body mass index, 25 ± 5 kg/m²; 26 [63%], male, 26 [63%] practicing physical activity) were evaluated. Baropodometer evaluations were performed in 3 walking cycles with 100 m each, and the reliability between the cycles was examined. Pressure points on the heel, first metatarsal, fifth metatarsal and total plantar pressure were analyzed and compared.

Results:

Moderate agreement was identified between the second and third cycles (ICC, 0.66; 95% CI, 0.14-0.83). Physical activity practitioners showed higher total plantar pressure (70.8 vs 68.2 Kpa; p = 0.04) and higher pressure in the heel (70.7 vs 68.1 Kpa; p = 0.036) in relation to sedentary ones.

Conclusion:

The insole was able to assess plant pressure with moderate reliability from the adaptation period. Level of Evidence III, Case control study - Investigating a diagnostic test.

Intra-subject sample size effects in plantar pressure analyses

Background

Recent work using large datasets (>500 records per subject) has demonstrated seemingly high levels of step-to-step variation in peak plantar pressure within human individuals during walking. One intuitive consequence of this variation is that smaller sample sizes (e.g., 10 steps per subject) may be quantitatively and qualitatively inaccurate and fail to capture the variance in plantar pressure of individuals seen in larger data sets. However, this remains quantitatively unexplored reflecting a lack of detailed investigation of intra-subject sample size effects in plantar pressure analysis.

Methods

Here we explore the sensitivity of various plantar pressure metrics to intra-subject sample size (number of steps per subject) using a random subsampling analysis. We randomly and incrementally subsample large data sets (>500 steps per subject) to compare variability in three metric types at sample sizes of 5–400 records: (1) overall whole-record mean and maximum pressure; (2) single-pixel values from five locations across the foot; and (3) the sum of pixel-level variability (measured by mean square error, MSE) from the whole plantar surface.

Results

Our results indicate that the central tendency of whole-record mean and maximum pressure within and across subjects show only minor sensitivity to sample size >200 steps. However, <200 steps, and particularly <50 steps, the range of overall mean and maximum pressure values yielded by our subsampling analysis increased considerably resulting in potential qualitative error in analyses of pressure changes with speed within-subjects and in comparisons of relative pressure magnitudes across subjects at a given speed. Our analysis revealed considerable variability in the absolute and relative response of the single pixel centroids of five regions to random subsampling. As the number of steps analysed decreased, the absolute value ranges were highest in the areas of highest pressure (medial forefoot and hallux), while the largest relative changes were seen in areas of lower pressure (the midfoot). Our pixel-level measure of variability by MSE across the whole-foot was highly sensitive to our manipulation of sample size, such that the range in MSE was exponentially larger in smaller subsamples. Random subsampling showed that the range in pixel-level MSE only came within 5% of the overall sample size in subsamples of >400 steps. The range in pixel-level MSE at low subsamples (<50) was 25–75% higher than that of the full datasets of >500 pressure records per subject. Overall, therefore, we demonstrate a high probability that the very small sample sizes (n < 20 records), which are routinely used in human and animal studies, capture a relatively low proportion of variance evident in larger plantar pressure data set, and thus may not accurately reflect the true population mean.

Insoles of uniform softer material reduced plantar pressure compared to dual-material insoles during regular and loaded gait

There is limited evidence on the efficacy of insole materials to reduce plantar pressure during regular walking and loaded walking. In-shoe plantar pressures and subjective footwear comfort were recorded in twenty healthy participants at a self-selected treadmill walking speed in six conditions: two commercial insoles or no insole, and with or without carrying a load in a backpack. A single-material insole, comprised of polyurethane, had reduced density and compressive stiffness compared to a dual-material insole with added viscoelastic material in rearfoot and forefoot regions. Load carriage increased peak pressure across the foot. Both insoles reduced plantar pressure in the rearfoot. Yet, the softer single-material insole also attenuated forefoot pressure and loaded walking did not appear to cause bottoming-out of the polyurethane. Plantar pressure changes did not affect perceived footwear comfort. The softer single-material insole was more effective in reducing plantar pressure, further research would confirm if this influences injury prevalence.

Minimal shoes improve stability and mobility in persons with a history of falls

Postural and walking instabilities contribute to falls in older adults. Given that shoes affect human locomotor stability and that visual, cognitive and somatosensory systems deteriorate during aging, we aimed to: (1) compare the effects of footwear type on stability and mobility in persons with a history of falls, and (2) determine whether the effect of footwear type on stability is altered by the absence of visual input or by an additional cognitive load. Thirty participants performed standing and walking trials in three footwear conditions, i.e. conventional shoes, minimal shoes, and barefoot. The outcomes were: (1) postural stability (movement of the center of pressure during eyes open/closed), (2) walking stability (Margin of Stability during normal/dual-task walking), (3) mobility (the Timed Up and Go test and the Star Excursion Balance test), and (4) perceptions of the shoes (Monitor Orthopaedic Shoes questionnaire). Participants were more stable during standing and walking in minimal shoes than in conventional shoes, independent of visual or walking condition. Minimal shoes were more beneficial for mobility than conventional shoes and barefoot. This study supports the need for longitudinal studies investigating whether minimal footwear is more beneficial for fall prevention in older people than conventional footwear.

Plantar pressure distribution and wearing characteristics of three forefoot offloading shoes in healthy adult subjects

Forefoot offloading shoes are used to reduce pressure on specific regions of the foot. Aim of the pressure reduction is to aid healing of the soft and bony tissues and prevent complications by treating foot disorders. A great variety of forefoot offloading shoes are available. In a first step to investigate the appropriate use of these footwear in orthopedic settings, we studied plantar pressure distribution and wearing characteristics of three forefoot offloading shoes namely the Mailand, OrthoWedge and Podalux in a healthy population. Twenty subjects walked in a randomized order wearing three forefoot offloading shoes and a reference shoe for six minutes. The Pedar system was used to measure the pressure in 7 regions. Peak pressure and pressure time integral were analyzed as measures of pressure distribution. Furthermore, wearing characteristics were addressed using a Numeric Rating Scale. Pressure distribution and wearing characteristics of the forefoot offloading shoes were compared to a reference shoe. The Mailand and OrthoWedge shoes significantly reduced peak pressure with more than 80% under the hallux and more than 45% under MTH1 (p<.001). The Podalux did not show significant peak pressure reduction under the forefoot compared to the reference shoe. Under the lesser toes, the MTH4-5 region and heel region the Podalux shoe showed even a significant increase in peak pressure (p=.001). Looking at wearing characteristics, the Podalux and reference shoe scored significantly better than the other two forefoot offloading shoes (p<.01). In this study the differences between different forefoot offloading shoes was assessed. The Mailand and OrthoWedge shoes gave the best pressure reduction in the forefoot but are less comfortable in use. The Podalux rocker shoe showed opposite results. Next step is a patient study to compare our results in a patient population.

Changes in plantar pressure and spatiotemporal parameters during gait in older adults after two different training programs

BACKGROUND

Improving gait is in exercise programs for older adults (OAs) but little is known about how different gait-training approaches affect spatiotemporal parameters and plantar pressure distributions in OAs. High plantar pressures are linked to tissue injury risk, ulceration, and pain in OAs, but no studies have yet compared how they affect podobarometric variables.

RESEARCH QUESTION

The effect of changing plantar pressure on absolute and mean maximum pressure, the pressure-time integral, stride time, stance time, and gait speed in OAs following either a multicomponent training program (EG) or interval-walking training (WG).

METHODS

Comfortable gait speed, strength (seat-to-stand test), and plantar pressure (Pedar-X mobile in-shoe system), were evaluated in 23 OAs (EG: n = 12, 7 female, 71.58 ± 4.56 years; WG: n = 11, 6 female, 69.64 ± 3.56 years), by dividing the plantar area into 9 regions.

RESULTS

After 14 weeks, the maximum pressure in medial and central metatarsus areas in the dominant leg were reduced in the EG (p = 0.01 &p = 0.04, respectively), but increased in the non-dominant leg lateral heel in the WG (p = 0.03). The mean maximum pressure also increased in the WG in medial heel in the dominant leg (p = 0.02) and lateral heel in the non-dominant leg (p = 0.03). The overall pressure-time integral reduced in the whole plantar area in both legs in both groups. WG reduced stride time (dominant: p = 0.01; non-dominant: p = 0.01) and stance time (dominant: p < 0.005; non-dominant: p < 0.005). Gait speed did not change in any group. As expected, lower limb strength improved after both exercise programs (EG: p = 0.02; WG: p = 0.01).

SIGNIFICANCE

Although these training interventions were short, they indicate the importance of exercise types. Our results suggest that OAs might benefit from periodized training, especially when multicomponent programs are introduced prior to the walking goals. Future, larger studies should explore situations in which special populations with specific foot problems might benefit from these interventions.

Minimal footwear improves stability and physical function in middle-aged and older people compared to conventional shoes

BACKGROUND

Effects of minimal shoes on stability and physical function in older people are under-researched. No studies have systematically explored effects of a range of minimal footwear features on these factors in older people.

METHODS

A within-participant repeated-measures design was used. Participants were subjected to thirteen footwear conditions: (i) barefoot, (ii) a conventional shoe, (iii) a control minimal shoe, (iv-xiii) minimal shoes differing from the control minimal shoe by one design feature. The outcomes were: (i) postural stability expressed with movement of the center of pressure (CoP) during standing (ii) dynamic stability expressed with the CoP movement during walking, (iv) physical function assessed with the Timed Up and Go test (TUG), and (iv) perceptions of footwear assessed with the Monitor Orthopaedic Shoes questionnaire. Linear Mixed Models were applied for statistical analyses.

FINDINGS

Twenty-two people participated in the study. Compared to the conventional shoe, participants: (i) were more stable during standing and walking in the majority of minimal shoes, and (ii) completed the TUG test faster when wearing the minimal shoe with wider sole. Compared to the control minimal shoe, participants: (i) completed the TUG test faster when wearing the minimal shoe with wider sole; and (ii) perceived features such as a split toe and a higher ankle collar as less fashionable and wearable.

INTERPRETATION

Wearing minimal shoes might be more beneficial for stability and physical function in older adults than wearing conventional shoes. The results will be highly valuable for the design of minimal footwear for older adults.

Gait stability of diabetic patients is altered with the rigid rocker shoes

BACKGROUND

Rigid-rocker shoes may induce gait instability in diabetics, however, this is not clearly investigated. The present study investigates if rigid-rocker shoes influence diabetic gait stability.

METHODS

Fourteen non-neuropathic and nine neuropathic diabetics, plus eleven healthy young-adults were recruited. Full-body kinematic data was captured during walking. Experimental conditions included barefoot and three rocker-shoe designs according to the rocker angle, apex angle and apex position (R10: 10°, 80°, 60%; R15: 15°, 95°, 52%; R20: 20°, 95°, 60%). Sagittal and frontal stability margin, plus fear of fall were main outcome measures.

FINDINGS

Sagittal stability margin was not affected by health, however, was increased with R10 and R15 in non-neuropathic diabetics and healthy individuals (R² = 0.16). Variability of sagittal stability margin was not altered in neuropathic diabetics, but was increased with R15 and R20 in healthy participants, with R15 in non-neuropathic diabetics (R² = 0.12). Frontal stability margin (R² = 0.46) and its variability (R² = 0.39) were significantly increased in neuropathic and non-neuropathic diabetics compared to healthy individuals. Frontal stability margin was significantly higher with R15 in neuropathic diabetics, and with R20 in both non-neuropathic and healthy participants. Sagittal and frontal stability margin were strongly correlated with fear of fall in neuropathic diabetics.

INTERPRETATIONS

R15 and R20 might challenge gait stability of diabetics cause them restrict centre of mass motion thereby imposing a tighter control over walking. However, neuropathic diabetics generally walk very cautious due to neuropathy and increased fear of fall. Frontal stability margin, highly affected by health and experimental condition, is a more sensitive indicator of gait stability.

Relationship between skin temperature monitoring with Smart Socks and plantar pressure distribution: a pilot study

OBJECTIVE

Increased skin temperature at the plantar aspect of the foot can predict foot ulceration. However its relation to plantar pressure overload is unknown. The aim of this study was to assess the ability of 'smart socks', monitoring plantar temperature under real-life conditions, to predict plantar pressure distribution.

METHOD

The 'smart socks' have seven thermal sensors woven into the fabric of the sock to measure the temperature beneath the foot in real-life conditions. The upper part of the sock is connected to a central unit through which changes in the sensor resistance is converted into temperature changes. Participants were instructed to wear the socks for three continuous hours. Plantar pressure was measured by the MatScan plantar-pressure measurement system (Tekscan Inc., US).

RESULTS

The study included 25 healthy volunteers (11 males, 14 females, mean age was 41.1 years (standard deviation (SD): 17.6) years, a mean body mass index of 29.4 kg/m² (SD: 6.95). Temperature changes at sensor (S) five significantly correlated with metatarsal (M) 2 pressure time integral (PTI) (r=0.519, p=0.008), M3 PTI (r=0.435, p=0.03), M4 PTI (r=0.452, p=0.023). Changes at S5 also significantly correlated with peak pressure at M2 (r=0.66, p=0.000), M3 (r=0.52, p=0.01), and M4 (r=0.60, p=0.002). Temperature changes at S6 were significantly correlated with changes at S1, S2, S3, S4, S5, and S7.

CONCLUSION

Temperature changes at the plantar aspect of the foot measured by the smart socks are correlated with plantar pressure distribution. Furthermore, two sensors at positions S5 and S6 were sufficient to predict plantar pressure changes.

A systematic review of shock-attenuating componentry for lower limb amputees

BACKGROUND

Shock-attenuating pylons are commonly fitted to prostheses in order to compensate for the anatomical and biomechanical shock-absorbing features of the lower limb removed upon amputation. However, studies concerning their shock-attenuating capacity are highly variable and, to date, have not yet been reviewed, making them difficult to interpret and apply in clinical practice.

OBJECTIVES

To synthesise and appraise the available literature examining the effectiveness of shock-attenuating pylons in attenuating shock upon limb loading compared to rigid pylons among lower limb amputees.

STUDY DESIGN

Systematic review.

METHODS

A comprehensive search of seven databases was conducted using search terms concerning amputation level, shock-attenuating and rigid pylons as well as measures of shock attenuation. All studies yielded were screened against established inclusion and exclusion criteria before eligible articles were appraised using the Quality Assessment Standard for Crossover Studies adapted from the Cochrane handbook.

RESULTS

Nine articles were eligible for inclusion. While there was a trend among studies to indicate only a limited positive effect of shock-attenuating pylons in attenuating transient impact forces, limitations to the study designs, namely, in sampling, poor reporting of methodological details and heterogeneity of outcomes made conclusive interpretation of results difficult.

CONCLUSION

While the current body of literature does not reconcile with claims made by manufacturers of shock-attenuating pylons, it is insufficient to conclusively determine how effective shock-attenuating pylons are, in comparison with conventional rigid pylons, in attenuating transient impact forces among lower limb amputees. Higher quality research is required to better guide decisions regarding prescription of shock-attenuating componentry in clinical practice. Clinical relevance When delivered well, research can provide clinicians with objective and reliable data that can be applied in their practice to guide prescription of componentry. However, methodological limitations to research may compromise the reliability of findings, thereby producing potentially misleading outcomes. These limitations must be recognised and appreciated such that findings may be interpreted accurately and applied appropriately.

Effect of different casting design characteristics on offloading the diabetic foot

BACKGROUND

Non-removable knee-high devices, such as a total contact cast (TCC), are recommended for offloading diabetic plantar forefoot ulcers. However, it is insufficiently known how each of the different design characteristics of these devices contribute to offloading the diabetic foot.

RESEARCH QUESTION

What is the offloading effect of the different design characteristics that make up a non-removable knee-high cast for people with diabetes and active or previous plantar forefoot ulcers?

METHODS

Sixteen persons with diabetes, peripheral neuropathy and a healed or active plantar forefoot ulcer had their plantar pressures measured during walking in a non-removable knee-high device (TCC), in that device made removable (BTCC), in that device made below-ankle (cast shoe), in that cast shoe worn with a different walking sole and in a newly made cast shoe without a custom-moulded foot-device interface. Peak pressures, force-time integral, and perceived walking comfort were assessed.

RESULTS

Compared with the BTCC, peak pressures in the TCC were 47% (P = 0.028), 26% (P = 0.003) and 15% (P = 0.050) lower at the hallux, midfoot and (previous) ulcer location, respectively. Compared to the cast shoe, peak pressures in the BTCC were 39-43% and 47% (both P < 0.001) lower in the forefoot regions and (previous) ulcer location, respectively. The total force-time integral was 21% and 11% (P < 0.007) lower in the TCC and BTCC compared to the cast shoe. Perceived walking comfort was 5.6 in the TCC and 6.5 in the BTCC (P = 0.037). Effects of the other design characteristics (i.e. walking sole and plantar moulding) were non-significant.

SIGNIFICANCE

The TCC gives superior offloading, mostly because of being a knee-high and non-removable device, providing an optimal 'shaft effect'. The TCC does, however, negatively affect walking comfort. These results aid decision-making in offloading diabetic plantar forefoot ulcers.

Sex Differences in Pedobarographic Findings and Relationship between Radiographic and Pedobarographic Measurements in Young Healthy Adults

Background

Although pedobarographic measurement is increasingly used for clinical and research purposes, relatively few published studies have investigated normative data. This study examined pedobarographic findings in young healthy adults with regard to sex-related differences and correlations among measurement indices.

Methods

Twenty young healthy adults (mean age, 22.4 years; standard deviation, 1.2 years; and 10 males and 10 females) were included. Weight bearing anteroposterior (AP) and lateral foot radiographs were taken, and dynamic pedobarographic data during treadmill walking and maximum ankle dorsiflexion were obtained. AP talo-first metatarsal angle, naviculocuboid overlap, lateral talo-first metatarsal angle, and plantar soft tissue thickness were measured on foot radiographs. Pedobarographic data including peak pressure and pressure-time integral were measured on five plantar segments: medial forefoot (MFF), lateral forefoot (LFF), medial midfoot (MMF), lateral midfoot (LMF), and heel.

Results

Male and female subjects significantly differed in body mass index (BMI, p < 0.001), AP talo-first metatarsal angle (p = 0.018), soft tissue thickness under the metatarsal head (p = 0.040) and calcaneal tuberosity (p < 0.001), maximum dorsiflexion during stance phase (p = 0.041), peak pressure on the MFF (p = 0.005) and LFF (p = 0.004), and pressure-time integral on the MFF (p = 0.018) and heel (p = 0.001). BMI was significantly correlated with soft tissue thickness under the metatarsal head (r = 0.521, p = 0.018) and calcaneal tuberosity (r = 0.585, p = 0.007), peak pressure on the MFF (r = 0.601, p = 0.005) and LFF (r = 0.487, p = 0.029), pressure-time integral on the heel (r = 0.552, p = 0.012), and total pressure-time integral (r = 0.755, p < 0.001). Maximum dorsiflexion demonstrated significant negative correlations with pressure-time integral on the MFF (r = −0.595, p = 0.007) and total pressure-time integral (r = −0.492, p = 0.032). Pressure-time integral varus/valgus index was significantly correlated with pressuretime integral forefoot/heel index (r = 0.472, p = 0.036).

Conclusions

Sex-related differences in pedobarographic examination were observed, which could provide useful information in setting appropriate treatment goals and obtaining appropriate control data. The effects of subtalar motion in distributing plantar pressure should be investigated in a future study.

Age-related plantar centre of pressure trajectory changes during barefoot walking

Plantar centre of pressure (COP) variables during gait have been used to predict risk of injury, or consequences thereof. The aim of this study was to determine the effect of age on the COP trajectory during barefoot gait at a self-selected speed. 287 participants (aged 18-80year, 163 women) walked barefoot at self-selected speed across a Footscan^® force platform, completing five trials for each side. COP trajectories were extracted and trajectory-level canonical correlation analysis was used to test their correlation with age. Post hoc linear regressions were performed on the medio-lateral (COPx) and anterior-posterior (COPy) components. The test statistic trajectory exceeded the critical threshold for the left (p=0.001) and right foot (p=0.003). Post hoc analyses showed positive correlation between age and COPx in late stance, placed more laterally with increasing age, while no significant correlation was found for COPy. While no significant correlations were observed for the test statistic trajectory during heel strike and mid-stance, post hoc analysis indicated that the COPx component was placed more laterally at heel strike for the left foot with increasing age (p=0.016). The findings suggest that older individuals tend to push-off with less metatarso-phalangeal dorsiflexion. These results do not necessarily imply that ageing itself causes the observed correlation. Further evidence is needed to determine whether the laterally placed COP during roll-off may be a useful factor for determining risk for falling in the older population, or as a risk for future injuries or overuse disorders.

Stiffness Effects in Rocker-Soled Shoes: Biomechanical Implications

Rocker-soled shoes provide a way to reduce the possible concentration of stress, as well as change movement patterns, during gait. This study attempts to examine how plantar force and spatio-temporal variables are affected by two rocker designs, one with softer and one with denser sole materials, by comparing them with the barefoot condition and with flat-soled shoes. Eleven subjects' gait parameters during walking and jogging were recorded. Our results showed that compared with barefoot walking, plantar forces were higher for flat shoes while lower for both types of rocker shoes, the softer-material rocker being the lowest. The plantar force of flat shoes is greater than the vertical ground reaction force, while that of both rocker shoes is much less, 13.87-30.55% body weight. However, as locomotion speed increased to jogging, for all shoe types, except at the second peak plantar force of the denser sole material rocker shoes, plantar forces were greater than for bare feet. More interestingly, because the transmission of force was faster while jogging, greater plantar force was seen in the rocker-soled shoes with softer material than with denser material; results for higher-speed shock absorption in rocker-soled shoes with softer material were thus not as good. In general, the rolling phenomena along the bottom surface of the rocker shoes, as well as an increase in the duration of simultaneous curve rolling and ankle rotation, could contribute to the reduction of plantar force for both rocker designs. The possible mechanism is the conversion of vertical kinetic energy into rotational kinetic energy. To conclude, since plantar force is related to foot-ground interface and deceleration methods, rocker-design shoes could achieve desired plantar force reduction through certain rolling phenomena, shoe-sole stiffness levels, and locomotion speeds.