Reliability of peak foot pressure in patients with previous diabetic foot ulceration

BackgroundPrevious reliability studies on peak plantar pressure measurements in patients with previous diabetic foot ulceration (DFU) did not stratify their analyses according to whether the foot had a previous ulcer.Research questionDoes test-retest reliability of peak foot pressure measurements from the various foot regions differ between the ulcerated and non-ulcerated feet?MethodsData from 23 participants with peripheral neuropathy and healed plantar DFU were analysed in this test-retest reliability comparison study. Plantar pressure was evaluated on two sessions using Pedar^®-X in-shoe system, with a mean of 7.2 days (SD = 1.6) between sessions.ResultsThe intraclass correlation coefficient (ICC) and coefficient of variation (CV) were calculated for 10 foot regions. Overall, test-retest reliability was excellent (ICCs, 0.82 to 0.95) for all peak pressure variables. CV ranged between 6.3% and 18.3%, and exceeded 15% over the hallux and medial forefoot regions in the ulcer foot (18.3% and 16.4%, respectively). Hallux peak pressure CV was significantly higher over the ulcer foot than over the non-ulcer foot (5.7%, 95% CI, 1.7%–10.2%). Peak pressure CV over the forefoot also tended to be higher over the ulcer foot (medial forefoot: 6.1%, 95% CI, -0.5%–14.5%; lateral forefoot: 4.1%, 95%CI, -0.7%–11.1%).SignificancePeak plantar foot pressure may be useful to distinguish between groups of patients with peripheral neuropathy and healed plantar DFU. However, clinical decisions based on ulcer foot hallux and forefoot peak pressure measurements should be interpreted with caution.     

A biomechanical assessment of the acute hallux abduction manipulation intervention

BackgroundNaturally aligned toes, particularly hallux, have reported with gripping functions during locomotion, thus expanding the forefoot loading area.Research questionThe purpose of this study was aimed to investigate the influence of hallux abduction manipulation on the foot plantar pressure distribution and inter-segment kinematic alterations.MethodsThirteen subjects participated in this toe manipulation study. A Footscan® pressure plate and Vicon motion capture system were utilized for the measurement of plantar pressure distribution and lower extremity and foot inter-segment kinematics during walking and running. Paired-sample t-test from statistical parametric mapping 1d was used to check the kinematic significance.ResultsPeak pressure in third metatarsal (M3) increased significantly during walking under manipulation. Contact area increased in second metatarsal (M2) with manipulation during running. Peak pressure and pressure-time integral illustrated significant increases in M3, and the maximum force and impulse in fourth metatarsal (M4) increased significantly. Arch height index increased while walking with toe manipulation. The foot progression angle in the frontal plane showed significant decrease in mid-swing phase during walking and significant increase in mid-stance phase during running. The hallux relative to forefoot angles presented higher axial rotation in the frontal plane.SignificanceFindings form this study showed centrally and laterally redistributed foot loadings and increased forefoot inter-segment flexibility with manipulation, which may be used as baseline to evaluate toe-manipulation interventions in foot disorders, specifically hallux valgus deformity.     

The influence of population characteristics and measurement system on barefoot plantar pressures: A systematic review and meta-regression analysis

BackgroundThe measurement of plantar pressure distributions during gait can provide insights into the effects of musculoskeletal disease on foot function. A range of hardware, software, and protocols are available for the collection of this type of data, with sometimes disparate and conflicting results reported between individual studies. In this systematic review and meta-regression analysis of dynamic regional peak pressures, we aimed to test if 1) the system used to obtain the pressure measurements and 2) the characteristics of the study populations had a significant effect on the results.MethodsA systematic review of the literature was undertaken to identify articles reporting regional peak plantar pressures during barefoot walking. A mixed-effects modeling approach was used to analyze the extracted data. Initially, the effect of the system used to collect the data was tested. Following this, the effect of participant characteristics on the results were analyzed, using moderators of cohort type (defined as the primary health characteristic of the participants), age, sex, and BMI.Results115 participant groups were included in the analysis. Sufficient cohorts were available to test those that consisted of healthy individuals, and those with diabetes and diabetic neuropathy. Significant differences were found between results reported by studies using different pressure measurement systems in 8 of the 16 regions analyzed. The analysis of participant characteristics revealed a number of significant relationships between regional peak pressures and participant characteristics, including: BMI and midfoot plantar pressures; elevated forefoot pressures as a result of diabetic neuropathy; and sex-differences in regional loading patterns.ConclusionsAt the level of the literature, we confirmed significant effects of disease status, age, BMI, and sex on regional peak plantar pressures. Researchers and clinicians should be aware that measurements of peak plantar pressure variables obtained from different collection equipment are not directly comparable.     

Abnormalities of plantar pressure distribution in early,intermediate, and late stages of diabetic neuropathy

Inconsistent findings with regard to plantar pressure while walking in the diabetic population may be due to the heterogeneity of the studied groups resulting from the classification/grouping criteria adopted. The clinical diagnosis and classification of diabetes have inherent uncertainties that compromise the definition of its onset and the differentiation of its severity stages. A fuzzy system could improve the precision of the diagnosis and classification of diabetic neuropathy because it takes those uncertainties into account and combines different assessment methods. Here, we investigated how plantar pressure abnormalities evolve throughout different severity stages of diabetic polyneuropathy (absent, n = 38; mild, n = 20; moderate, n = 47; severe, n = 24). Pressure distribution was analysed over five areas while patients walked barefoot. Patients with mild neuropathy displayed an increase in pressure–time integral at the forefoot and a lower peak pressure at the heel. The peak and pressure–time integral under the forefoot and heel were aggravated in later stages of the disease (moderate and severe) compared with early stages of the disease (absent and mild). In the severe group, lower pressures at the lateral forefoot and hallux were observed, which could be related to symptoms that develop with the aggravation of neuropathy: atrophy of the intrinsic foot muscles, reduction of distal muscle activity, and joint stiffness. Although there were clear alterations over the forefoot and in a number of plantar areas with higher pressures within each severity stage, they did not follow the aggravation evolution of neuropathy classified by the fuzzy model. Based on these results, therapeutic interventions should begin in the early stages of this disease to prevent further consequences of the disease.     

Elevated plantar pressure in diabetic patients and its relationship with their gait features

PurposeHigh plantar pressure is a major risk factor for diabetic foot ulcers. The relationship between plantar pressure and foot mobility has been investigated in some studies. However, when the foot is in motion, foot mobility is only a small feature of the gait. Therefore, we investigated relationship between high plantar pressure and gait and also studied the motion of the trunk. In addition, we investigated the relationship between gait and patient characteristics to identify patients at high-risk of developing diabetic foot ulcers.MethodsThe relationships between elevated plantar pressure, gait features, and patient characteristics were analyzed. Plantar pressure distribution in the stance phase was divided on the four plantar segments. Elevated plantar pressure was defined as being more than the mean plus one standard deviation of the corresponding segment in non-diabetic subjects. Plantar pressure distribution was measured by an F-scan system, and gait features were measured using wireless motion sensors attached to the sacrum and feet. Patient characteristics were obtained from medical records or by interview.ResultsSmall roll and yaw motions of the body and yaw motion of the foot during the mid-stance phase were related to the elevated plantar pressure in 57 diabetic patients. Furthermore, these gait features were related to sensory neuropathy, diabetes duration, patient weight, toe-gap force, and ankle range of motion.ConclusionGiven our findings, it may be possible to prevent diabetic foot ulcers by increasing foot motion during the mid-stance phase. Passive exercise aimed at expanding ankle range of motion in patients with sensory neuropathy or long-standing diabetes may assist in achieving this.     

Abnormalities of plantar pressure distribution in early,intermediate, and late stages of diabetic neuropathy

Inconsistent findings with regard to plantar pressure while walking in the diabetic population may be due to the heterogeneity of the studied groups resulting from the classification/grouping criteria adopted. The clinical diagnosis and classification of diabetes have inherent uncertainties that compromise the definition of its onset and the differentiation of its severity stages. A fuzzy system could improve the precision of the diagnosis and classification of diabetic neuropathy because it takes those uncertainties into account and combines different assessment methods. Here, we investigated how plantar pressure abnormalities evolve throughout different severity stages of diabetic polyneuropathy (absent, n = 38; mild, n = 20; moderate, n = 47; severe, n = 24). Pressure distribution was analysed over five areas while patients walked barefoot. Patients with mild neuropathy displayed an increase in pressure–time integral at the forefoot and a lower peak pressure at the heel. The peak and pressure–time integral under the forefoot and heel were aggravated in later stages of the disease (moderate and severe) compared with early stages of the disease (absent and mild). In the severe group, lower pressures at the lateral forefoot and hallux were observed, which could be related to symptoms that develop with the aggravation of neuropathy: atrophy of the intrinsic foot muscles, reduction of distal muscle activity, and joint stiffness. Although there were clear alterations over the forefoot and in a number of plantar areas with higher pressures within each severity stage, they did not follow the aggravation evolution of neuropathy classified by the fuzzy model. Based on these results, therapeutic interventions should begin in the early stages of this disease to prevent further consequences of the disease.     

Changes to stance limb peak,cumulative, and regional plantar foot forces among normal walking and three mobility aids in healthy older adults

BackgroundMobility aids are commonly prescribed to offload an injured lower extremity. Device selection may impact stance foot loading patterns and foot health in clinical populations at risk of foot ulceration.Research questionsTwo questions motivated this study: How does device selection influence peak plantar and regional (rearfoot, mid foot and forefoot) foot forces on the stance foot? Does device selection influence peak, cumulative, and regional plantar forces within a 200 m walking trial?MethodsTwenty-one older adults walked 200 m at self-selected pace in four randomized conditions for this prospective crossover study. Participants used a walker, crutches, wheeled knee walker (WKW), and no assistive device (control condition). Plantar forces were measured using a wireless in-shoe system (Loadsol, Novel Inc., St. Paul, MN). Repeated measures analyses of variance were used to determine differences in peak and cumulative total and regional forces among walking conditions. Paired sample t-tests compared forces during first and last 30 s epochs of each condition to determine device influence over time.ResultsThe WKW reduced peak net forces by 0.29 and 0.35 bodyweight (BW) when compared to the walker or control condition with similar trends in all foot regions. Crutch use had similar peak forces as control. There were no differences in the number of steps taken within devices comparing first and last epochs. Crutches had a 0.04 and 0.07 BW increase in peak net and forefoot forces during the last epoch. Walker use had 66.44 BW lower cumulative forefoot forces in the last epoch.SignificanceCrutches had similar stance foot loading as normal walking while a walker lowered forefoot forces at the expense of increased steps. A WKW may be the best choice to ‘protect’ tissues in the stance foot from exposure to peak and cumulative forces in the forefoot region.     

Understanding the role of foot biomechanics on regional foot orthosis deformation in flatfoot individuals during walking

BackgroundFoot orthoses (FOs) are one of the most common interventions to restore normal foot mechanics in flatfoot individuals. New technologies have made it possible to deliver customized FOs with complex designs for potentially better functionalities. However, translating the individuals’ biomechanical needs into the design of customized FOs is not yet fully understood.Research questionOur objective was to identify whether the deformation of customized FOs is related to foot kinematics and plantar pressure during walking.MethodsThe kinematics of multi-segment foot and FOs contour were recorded together with plantar pressure in 17 flatfoot individuals while walking with customized FOs. The deformation of FOs surface was predicted from its contour kinematics using an artificial neural network. Plantar pressure map and deformation were divided into five anatomically based regions defined by the corresponding foot segments. Forward stepwise linear mixed models were built for each of the four gait phases to determine the feet-FOs interaction.ResultsIt was observed that some associations existed between foot kinematics and pressure with regional FOs deformation. From heel-strike to foot-flat, longitudinal arch angle was associated with FOs deformation in forefoot. From foot-flat to midstance, rearfoot eversion accounted for variation in the deformation of medial FOs regions, and forefoot abduction for the lateral regions. From midstance to heel-off, rearfoot eversion, longitudinal arch angle, and plantar pressure played significant role in deformation. Finally, from heel-off to toe-off, forefoot adduction affected the deformation of forefoot and midfoot.SignificanceThis study provides guidelines for designing customized FOs. Flatfoot individuals with excessive rearfoot eversion or very flexible medial arches require more support on medial FOs regions, while the ones with excessive forefoot abduction need the support on lateral regions. However, a compromise should be made between the level of support and the level of increase in plantar pressure to avoid stress on foot structures.     

Regional plantar pressure during walking, stair ascent and descent

Regional plantar pressures during stair walking may be injurious in at risk populations. However, limited data are available examining the reliability of plantar pressure data collected during stair walking. The aims of this study were three fold; to assess the reliability of the plantar pressure data recorded during stair walking, to assess the effects of level ground and stair walking on plantar loading, and to develop regression equations to predict regional plantar pressures in stair walking from those collected on level ground. Fifteen subjects without conditions affecting their ability to walk on level surfaces or stairs were recruited. Each participant performed at least 10 steps in level ground and stair walking while plantar pressure data were recorded in six foot regions. Reliability was assessed using Intraclass Correlation Coefficient. A repeated measures ANOVA was used to assess the effect of activity on plantar pressure, and a linear regression was used to predict forefoot loading during stair walking. A reliability of 0.9 was achieved within 10 steps in all foot regions, with the forefoot requiring fewer steps. Plantar pressures were influenced by both, foot region and activity, with the heel and forefoot regions generally experiencing lower peak pressures and maximal forces during stair walking than level ground walking. The regression equations predicting peak pressure during stair walking accounted for between 37% and 70% of the variance of the stair walking data. These findings establish the reliability of plantar pressure data collected during stair walking. Future studies should investigate these parameters in clinical populations.     

Alterations to plantar loading and ankle range of motion of the contralateral foot during assisted walking in patients with Type 2 Diabetes Mellitus

AimsPatients with diabetic foot ulcers are instructed to be non-weight bearing on the affected limb to promote healing. Therefore, the aim of this study was to investigate the effect of different assistive devices on whole foot plantar loading, peak forefoot force, ankle range of motion, and locomotion speed during gait in patients with Type 2 Diabetes Mellitus.MethodsParticipants walked normally, with crutches, a walker, and a wheeled knee walker (WKW) in randomized order. Force sensitive insoles and 3D motion capture were used to record plantar normal force and ankle kinematics. Force sensitive pads were wrapped around handles of the crutches and walker to measure bodyweight offloaded onto the assistive device. An instrumented WKW was used to measure bodyweight offloaded onto the handlebars and knee cushion.ResultsLocomotion with the WKW produced the lowest whole foot plantar loading and peak forefoot force in the propulsive limb, while also producing the greatest ankle range of motion and locomotion speed amongst assistive devices.ConclusionsThis pre-clinical study found that the WKW could be the preferred assistive device for total unilateral offloading of diabetic foot ulcers as it reduced propulsive limb whole foot and forefoot plantar loading while retaining ankle range of motion and locomotion speed.     

Simultaneous measurement of plantar pressure and shear forces in diabetic individuals.

Plantar foot ulceration is a diabetic complication whose underlying causative factors are still not fully understood. The goal of the current work was to simultaneously record plantar pressure and shear and examine the interrelationship of these forces; specifically, if peak shear and pressure occurred at the same site/time and whether adjacent shear forces had a greater tendency to be directed towards or away from each other. A custom built 16 transducer array was used to record forefoot shear and pressure during gait initiation in a cohort of 12 neuropathic diabetic individuals. The individuals were barefoot and the transducers were covered with a 5 mm thick layer of Minorplast. The greatest pressure occurred in the medial metatarsal heads (189 kPa) and the greatest shear in the lateral metatarsal heads (33 kPa). The interaction of the shear forces revealed that the plantar tissue was stretched to a greater magnitude than it was bunched (24 kPa vs 12 kPa, averaged over all regions). Normal distributions were determined for stretching and bunching in both the medial-lateral and anterior-posterior directions. When shear and pressure were considered in combination, half of the neuropathic individuals had peak shear and pressure occurring at the same site. These peak stresses did not occur at the same time (average difference of 0.186 s). The results of this study help to further characterize tissue stresses experienced on the plantar surface of the foot during gait initiation in neuropathic diabetic individuals.     

Dynamic plantar pressure patterns in children and adolescents with Charcot-Marie-Tooth disease

BackgroundThe dynamic plantar pressure patterns of children and adolescents with Charcot-Marie-Tooth (CMT) disease and its relationship to musculoskeletal alterations may help to understand the natural history of the disease and improve therapeutic interventions.Research questionThe study compared dynamic plantar pressure patterns in children and adolescents with and without CMT. It also tested the associations between isometric muscle strength (IMS), passive range of motion (ROM), foot posture and dynamic plantar pressure patterns in CMT.MethodsThis cross-sectional study compared children and adolescents (aged 8–18 years) with CMT (n = 40) with a typical group (n = 40). The plantar pressure distribution during gait was recorded, and the contact area (CA), peak pressure (PP), contact time (CT) and pressure-time integral (PTI) in five foot regions (rearfoot, midfoot lateral, midfoot medial, lateral forefoot and medial forefoot) were analysed. The IMS of the dorsiflexors and plantar flexors, passive ROM, and foot posture were also recorded.ResultsPP (medial midfoot and medial forefoot) and PTI (rearfoot, lateral midfoot and medial forefoot) were higher in children with CMT compared with the typical group. The adolescents with CMT presented a less CA (whole foot) and a higher CT (medial midfoot) when compared with typical group. For CMT, in the medial midfoot, plantar flexor IMS associated with PP (β=-11.54, p = 0.01) and PTI (β=-3.38, p = 0.04); supinated foot posture associated with PP (β = 33.89, p = 0.03) and PTI (β = 12.01, p = 0.03).SignificanceChildren with CMT showed clear changes in most of the dynamic plantar pressure variables, while adolescents with CMT showed changes mostly in CA and CT. This information together with the associations established between supinated foot, dorsiflexion ROM and plantar flexions IMS can be useful for guiding rehabilitation professionals in their therapies.     

External feedback during walking improves measures of plantar pressure in individuals with chronic ankle instability

BackgroundIndividuals with chronic ankle instability (CAI) commonly present with an altered walking gait which favors the lateral aspect of their foot. Current rehabilitative protocols are unable to address these gait modifications which are potentially hindering improvements in patient-reported outcomes. Protocols for gait retraining are scarce, thus there is a need to develop intervention strategies and instruments to specifically target foot motion to address gait deficits in individuals with CAI.Research QuestionTo determine the ability of a novel laser device providing external visual feedback (ExFB) during real-time to cause alterations in plantar pressure measures in individuals with CAI.MethodsTwenty-six participants with CAI walked on a treadmill while real-time plantar pressure measures were being recorded during a baseline and feedback condition. Baseline trials were compared with ExFB trials within each subject.ResultsThe ExFB condition was able to significantly reduce plantar pressures on the lateral midfoot and forefoot compared to baseline. A statistically significant medial shift in center of pressure trajectory was also observed in the ExFB condition compared to baseline.SignificanceReal-time external feedback provided by a novel laser device has the ability to reduce lateral column plantar pressures during walking in individuals with CAI.     

Pressure characteristics in painful pes cavus feet resulting from Charcot-Marie-Tooth disease

Charcot–Marie–Tooth (CMT) disease often presents with peripheral muscle imbalance associated with a painful cavus (medial high-arched) foot deformity which becomes increasingly severe and rigid as the disease progresses. The purpose of this study was to investigate the effect of pes cavus on foot pain and dynamic plantar pressure in CMT, and to explore the relationships between plantar pressure and pain. Sixteen participants diagnosed with CMT and painful pes cavus were assessed for foot posture, ankle dorsiflexion range of motion, levels of foot pain, functional impairment, health-related quality of life and plantar pressure distribution while walking. Plantar pressure parameters (mean pressure, peak pressure, pressure–time integral) and contact duration were measured using the Novel Pedar^® in-shoe capacitance transducer system and the foot was divided into rearfoot, midfoot and forefoot regions for analysis. Increasing cavus foot deformity was associated with more widespread foot pain and increased pressure under the forefoot and midfoot regions. In contrast, peak pressure decreased under the rearfoot. Neither relationship was found between foot pain intensity and any of the pressure variables, nor was ankle dorsiflexion range of motion correlated with pain location, intensity or degree of pes cavus. Although pes cavus in CMT is associated with substantial pain and dysfunction, there is no clear link between foot pain and plantar pressure. The more severe the degree of pes cavus, however, the more pressure develops under the lateral margin of the foot; probably as a result of the changed foot–ground contact seen during gait.     

Comparison of muscle activity during walking in subjects with and without diabetic neuropathy

The purpose of this study was to compare muscle activity and joint moments in the lower extremities during walking between subjects with diabetic neuropathy (DN) and control subjects. Tests were performed on nine subjects with DN, and nine age, gender, and weight-matched controls. Onset and cessation times of lower extremity electromyographic (EMG) activity and joint moments were determined. Results demonstrated that subjects with DN had less ankle mobility, slower walking speeds, longer stance phases, and lower peak ankle dorsiflexion, ankle plantar flexion, and knee extension moments than control subjects. Onset times with respect to heel-strike (HS) for the soleus, medial gastrocnemius, and medial hamstring muscles were significantly earlier during the gait cycle (GC) in subjects with DN than in control subjects. The cessation times of soleus, tibialis anterior, vastus medialis, and medial hamstring muscles were significantly prolonged in subjects with DN. Subjects with DN showed more co-contractions of agonist and antagonist muscles at the ankle and knee joints during stance phase compared with control subjects. These gait changes and co-contractions may allow subjects with DN to adopt a safer, more stable gait pattern to compensate for diminished sensory information from the ankle and the foot. The premature activation of soleus and medial gastrocnemius muscles in subjects with DN could be contributing to abnormal forefoot plantar pressure distribution. Additional research is needed to clarify the relationship between the premature activation of triceps surae muscles and the forefoot plantar pressure parameters in subjects with DN.     

Effects of rocker radii with two longitudinal bending stiffnesses on plantar pressure distribution in the forefoot

IntroductionOutsole parameters of the shoe can be adapted to offload regions of pain or region of high pressures. Previous studies already showed reduced plantar pressures in the forefoot due to a proximally placed apex position and higher longitudinal bending stiffness (LBS). The aim of this study was to determine the effect of changes in rocker radii and high LBS on the plantar pressure profile during gait.Method10 participants walked in seven shoe conditions of which one control shoe and six rocker shoes with small, medium and large rocker radii and low and high longitudinal bending stiffness. Pedar in-shoe plantar pressure measuring system was used to quantify plantar pressures while walking on a treadmill at self-selected walking speed. Peak plantar pressure, maximum mean pressure and force-time integral were analyzed with Generalized Estimated Equation (GEE) and Tukey post hoc correction (α = .05).ResultsSignificantly lower plantar pressures were found in the first toe, toes 2–5, distal and proximal forefoot in all rocker shoe conditions as compared to the control shoe. Plantar pressures in the first toe and toes 2–5 were significantly lower in the small radius compared to medium and large radii. For the distal forefoot both small and medium radii significantly reduced plantar pressure compared to large radii. Low LBS reduced plantar pressure at the first toe significantly compared to high LBS independent of the rocker radius. Plantar pressures in the distal forefoot and toes 2–5 were lower in high LBS compared to low LBS.ConclusionManipulation of the rocker radius and LBS can effectively reduce peak plantar pressures in the forefoot region during gait. In line with previous studies, we showed that depending on the exact target location for offloading, different combinations of rocker radius and LBS need to be adopted to maximize treatment effects.     

Effects of running-induced fatigue on plantar pressure distribution in runners with different strike types

BackgroundRunning induced-fatigue is an important factor in running related injuries. Runners with different strike types have different running mechanics and suffer from different injury patterns. Underlying mechanism of this difference is not well understood.Research questionThe aim of this study was to examine the effects of running-induced fatigue on plantar pressure distribution in runners with different strike types.Methods30 rearfoot (age = 21.56 ± 2.28 years; height = 1.67 ± 0.08 m; mass = 61.43 ± 11.57 kg; BMI = 21.77 ± 2.9 kg∙m⁻²) and 30 forefoot (age = 19.73 ± 1.68 years; height = 1.71 ± 0.08 m; mass = 65.7 ± 13.45; BMI = 22.53 ± 3.39 kg∙m⁻²) strike male and female recreational runners were recruited to this study. Participants ran in 3.3 m/s barefoot along the plantar pressure measuring device (Footscan®, Rsscan International) before and after running-induced fatigue. Fatigue protocol was performed on a treadmill. Peak plantar pressure and peak plantar force (% body weight), contact time and medio-lateral force ratio were calculated while running. Repeated measures ANOVA test was used to investigate the effect of running-induced fatigue on plantar pressure variables (p ≤ 0.05).ResultsAfter running-induced fatigue, in the rearfoot strike group, increases in loading of medial and lateral portions of the heel, first metatarsal and big toe was observed, and in lesser toes and in the forefoot push off phase, the medio-lateral force ratio decreased. While, in the forefoot strike group first to third metatarsals loading increased and fifth metatarsal loading decreased after fatigue, and medio-lateral force ratio in the foot flat and forefoot push off phase increased. In both groups contact time increased after fatigue.SignificanceOur data indicate that running-induced fatigue has different effects on plantar pressure distribution pattern in runners with different strike type. These different effects reflect different adaptation strategies in runners with different strike types, and could explain existence of different injury patterns in runners with different strike types.     

Between-day reliability of repeated plantar pressure distribution measurements in a normal population

The objective of this study was to determine the reliability of repeated plantar pressure distribution measurements during normal gait across multiple testing sessions. Testing sessions were conducted on 5 separate days at approximately the same time of day. Nine subjects (five males, four females, age 26 ± 8.4 years) who were free of any musculoskeletal injury were recruited. A capacitive pressure distribution platform (EMED AT, Novel GmbH, Munich, Germany), sampling at 50 Hz was used to collect plantar pressure patterns during barefoot walking at a self-selected speed. Four parameters were investigated: peak pressure, maximum force, impulse, and contact time, and these were investigated in 10 areas of the foot after using the PRC mask method of subdividing the foot into ten anatomical areas of interest. Individual means of all the five repeated trials for each foot were calculated, and these values were used to calculate intraclass correlation coefficients (ICC) and coefficients of variation (CoV) for all parameters. The results of this investigation show a generally good level of reliability, the quality of which is dependent on the region of the foot and the parameter investigated. Areas with typically high loading characteristics, such as the central forefoot showed a higher level of reliability in the ICC's (>0.9) than less loaded areas such as the medial midfoot (<0.8). The conclusion of this study is that plantar pressure distribution measurements can be used in comparative evaluations since the measures of repeatability are satisfactory for the parameters and foot regions usually used in the investigation of clinical populations such as neuropathic diabetics.     

Vertical ground reaction forces during gait in children with and without calcaneal apophysitis

BackgroundHeightened vertical load beneath the foot has been anecdotally implicated in the development of activity-related heel pain of the calcaneal apophysis in children but is supported by limited evidence.Research questionThis study investigated whether vertical loading patterns during walking and running differed in children with and without calcaneal apophysitis.MethodsVertical ground reaction force, peak plantar pressure (forefoot, midfoot, heel) and temporospatial gait parameters (cadence, step length, stride, stance and swing phase durations) were determined in children with (n = 14) and without (n = 14) calcaneal apophysitis. Measures were acquired during barefoot walking and running at matched and self-selected speed using an instrumented treadmill, sampling at 120 Hz. Statistical comparisons between groups were made using repeated measure ANOVAs.ResultsThere were no significant between group differences in vertical ground reaction force peaks or regional peak plantar pressures. However, when normalised to stature, cadence was significantly higher (≈ 5%) and step length shorter (≈ 5%) in children with calcaneal apophysitis than those without, but only during running (P <.05). Maximum pressure beneath the rearfoot during running was significantly correlated with self-reported pain in children with calcaneal apophysitis.SignificancePeak vertical force and plantar pressures did not differ significantly in children with and without calcaneal apophysitis during walking or running. However, children with calcaneal apophysitis adopted a higher cadence than children without heel pain during running. While the findings suggest that children with calcaneal apophysitis may alter their cadence to lower pressure beneath the heel and, hence pain, they also highlight the benefit of evaluating running rather than walking gait in children with calcaneal apophysitis.