Background Several footwear design characteristics are known to have detrimental effects on the foot. However, one characteristic that has received relatively little attention is the point where the sole flexes in the sagittal plane. Several footwear assessment forms assume that this should ideally be located directly under the metarsophalangeal joints (MTPJs), but this has not been directly evaluated. The aim of this study was therefore to assess the influence on plantar loading of different locations of the shoe sole flexion point. Method Twenty-one asymptomatic females with normal foot posture participated. Standardised shoes were incised directly underneath the metatarsophalangeal joints, proximal to the MTPJs or underneath the midfoot. The participants walked in a randomised sequence of the three shoes whilst plantar loading patterns were obtained using the Pedar® in-shoe pressure measurement system. The foot was divided into nine anatomically important masks, and peak pressure (PP), contact time (CT) and pressure time integral (PTI) were determined. A ratio of PP and PTI between MTPJ2-3/MTPJ1 was also calculated. Results Wearing the shoe with the sole flexion point located proximal to the MTPJs resulted in increased PP under MTPJ 4–5 (6.2%) and decreased PP under the medial midfoot compared to the sub-MTPJ flexion point (−8.4%). Wearing the shoe with the sole flexion point located under the midfoot resulted in decreased PP, CT and PTI in the medial and lateral hindfoot (PP: −4.2% and −5.1%, CT: −3.4% and −6.6%, PTI: −6.9% and −5.7%) and medial midfoot (PP: −5.9% CT: −2.9% PTI: −12.2%) compared to the other two shoes. Conclusion The findings of this study indicate that the location of the sole flexion point of the shoe influences plantar loading patterns during gait. Specifically, shoes with a sole flexion point located under the midfoot significantly decrease the magnitude and duration of loading under the midfoot and hindfoot, which may be indicative of an earlier heel lift.
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Background. Barefoot plantar pressure measurements are routinely used in the risk evaluation for ulceration in diabetic patients with neuropathy. The aim was to compare three step-protocols commonly used for pressure assessment in these patients. Methods. Dynamic barefoot plantar pressures were measured in 14 diabetic neuropathic patients (vibration perception threshold >35 V) contacting a pressure platform on the first, second or third step after gait initiation. Ten repeated trials per step-protocol were collected. The 3-step protocol was regarded the reference protocol. Peak pressure, pressure-time integral and contact time were calculated for each of six anatomical foot regions. Intraclass correlation coefficients (ICC) were calculated to assess reliability in each protocol. Findings. Regional peak pressures and pressure-time integrals were not significantly different between protocols. Contact time was significantly different in the heel region between the 1-step and 3-step protocol only (P < 0.05). Intraclass correlation coefficients for the maximum 10 repeated trials were high (>0.87) and similar between protocols. Reliable estimates (ICC > 0.85) of peak pressure were achieved with three repeated trials in the 2-step protocol, and four in the other two; for pressure-time integral these numbers were 7 (1-step), 4 (2-step), and 5 trials (3-step). Interpretation. Barefoot plantar pressures in the diabetic neuropathic foot can be assessed in a reproducible manner with any of the step-protocols used. For this purpose, the 1-step and 2-step protocols prove to be valid methods. A 2-step protocol requires the least amount of repeated trials for obtaining reliable pressure data and may be recommended for assessment of these patients.
Elevated plantar foot pressures during gait in diabetic patients with neuropathy have been suggested to result, among other factors, from the distal displacement of sub-metatarsal head (MTH) fat-pad cushions caused by to claw/hammer toe deformity. The purpose of this study was to quantitatively assess these associations. Thirteen neuropathic diabetic subjects with claw/hammer toe deformity, and 13 age- and gender-matched neuropathic diabetic controls without deformity, were examined. Dynamic barefoot plantar pressures were measured with an EMED pressure platform. Peak pressure and force-time integral for each of 11 foot regions were calculated. Degree of toe deformity and the ratio of sub-MTH to sub-phalangeal fat-pad thickness (indicating fat-pad displacement) were measured from sagittal plane magnetic resonance images of the foot. Peak pressures at the MTHs were significantly higher in the patients with toe deformity (mean 626 (SD 260) kPa) when compared with controls (mean 363 (SD 115) kPa, Po0.005). MTH peak pressure was significantly correlated with degree of toe deformity (r= 0.74) and with fat-pad displacement (r= 0.71) (Po0.001). The ratio of force-time integral in the toes and the MTHs (toe-loading index) was significantly lower in the group with deformity. These results show that claw/hammer toe deformity is associated with a distal-to-proximal transfer of load in the forefoot and elevated plantar pressures at the MTHs in neuropathic diabetic patients. Distal displacement of the plantar fat pad is suggested to be the underlying mechanism in this association. These conditions increase the risk for plantar ulceration in these patients.
In Europe nearly 10% of the population suffers from diabetes and almost 1% from Rheumatoid Arthritis which can lead to serious problems with mobility and active participation, especially in the ageing population. Pedorthists deliver personalised designed and manufactured orthopaedic footwear or insoles for these patients. However, despite their often laborious efforts upfront, the industry has very little means to quantify how successful the fitting and function of a shoe is. They have to rely on subjective, qualitative measures such as client satisfaction and diminishing of complaints. Although valuable, the need for objective quantitative data in this field is growing. Foot plantar pressure and shear forces are considered major indicators of potential foot problems. Devices to measure plantar pressure slowly gain terrain as providers of objective quantitative data to guide orthotic design and manufacturing. For shear forces however, measuring devices are not yet commercial available. Although shear forces are considered as a major contributor to ulcer formation in diabetic feet, their exact role still requires elucidation and quantification. This project aims to develop a prototype of an in-shoe wearable device that measures both shear forces and pressure using state-of-the-art developments in sensor technologies, smart textiles and wireless data transfer. The collaboration of pedorthists’ small and medium-sized enterprises (SME)’s with medical device engineering companies, knowledge institutes,technical universities and universities of applied sciences in this project will bring together the different fields of expertise required to create an innovative device. It is expected that the tool will be beneficial to improve the quality of pedorthists’ services and potentially reduce health insurance costs. Furthermore, it can be used in new shear forces research and open new business potential. However, the eventual aim is to improve patient care and help maintain personal mobility and participation in society.
