Dynamic impression insole in rheumatoid foot with metatarsal pain

Biomechanical investigation of a custom-made insole to decrease plantar pain of children with flatfoot: A technical note

OBJECTIVE

The abnormal plantar pressure of flatfoot patients is a common condition. The main objective of the present study was to investigate the effect of custom-molded insole on the plantar pain of flatfoot METHODS: 105 patients (representing 174 feet) participated in evaluating a custom-made orthotic insole from June 2018 to March 2019. The height of the navicular tubercle (HNT) and the deflection angle of calcaneus (DAC) in flatfoot patients after using orthotic insoles for 6 months were recorded by X-ray imaging and scanning measurements. Plantar pressure on metatarsals 1-5 was measured by using an RSscan system RESULTS: Without the use of an orthotic insole, mean HNT was 0.99±0.34 cm and mean DAC was 20.0 ± 3.78 ° during the bearing weight. After using the insole, mean HNT and DAC values reduced to 0.87±0.30 cm and 14.3 ± 3.45 °, respectively (P < 0.05). Hindfoot plantar pressure did not change significantly (P > 0.05). Furthermore, pressure at metatarsals 1-3 decreased by 48.5 %, 45.6 %, and 14.3 %, respectively; that at metatarsals 4-5 increased by 33.3 % and 137.5 %, separately, when using the custom-made insole CONCLUSIONS: Visual analog scale score for plantar pain was significantly reduced. These findings indicate that metatarsal pain of flatfoot patients might be the cause of load imbalance in plantar foot.

pressuRe: an R package for analyzing and visualizing biomechanical pressure distribution data

In many biomechanical analyses, the forces acting on a body during dynamic and static activities are often simplified as point loads. However, it is usually more accurate to characterize these forces as distributed loads, varying in magnitude and direction, over a given contact area. Evaluating these pressure distributions while they are applied to different parts of the body can provide effective insights for clinicians and researchers when studying health and disease conditions, for example when investigating the biomechanical factors that may lead to plantar ulceration in diabetic foot disease. At present, most processing and analysis for pressure data is performed using proprietary software, limiting reproducibility, transparency, and consistency across different studies. This paper describes an open-source software package, 'pressuRe', which is built in the freely available R statistical computing environment and is designed to process, analyze, and visualize pressure data collected on a range of different hardware systems in a standardized manner. We demonstrate the use of the package on pressure dataset from patients with diabetic foot disease, comparing pressure variables between those with longer and shorter durations of the disease. The results matched closely with those from commercially available software, and individuals with longer duration of diabetes were found to have higher forefoot pressures than those with shorter duration. By utilizing R's powerful and openly available tools for statistical analysis and user customization, this package may be a useful tool for researchers and clinicians studying plantar pressures and other pressure sensor array based biomechanical measurements. With regular updates intended, this package allows for continued improvement and we welcome feedback and future contributions to extend its scope. In this article, we detail the package's features and functionality.

Developing a core outcome set for foot and ankle disorders in rheumatic and musculoskeletal diseases: A scoping review and report from the OMERACT 2022 foot and ankle special interest group session

OBJECTIVES

Foot and ankle involvement is common in rheumatic and musculoskeletal diseases, yet high-quality evidence assessing the effectiveness of treatments for these disorders is lacking. The Outcome Measures in Rheumatology (OMERACT) Foot and Ankle Working Group is developing a core outcome set for use in clinical trials and longitudinal observational studies in this area.

METHODS

A scoping review was performed to identify outcome domains in the existing literature. Clinical trials and observational studies comparing pharmacological, conservative or surgical interventions involving adult participants with any foot or ankle disorder in the following rheumatic and musculoskeletal diseases (RMDs) were eligible for inclusion: rheumatoid arthritis (RA), osteoarthritis (OA), spondyloarthropathies, crystal arthropathies and connective tissue diseases. Outcome domains were categorised according to the OMERACT Filter 2.1.

RESULTS

Outcome domains were extracted from 150 eligible studies. Most studies included participants with foot/ankle OA (63% of studies) or foot/ankle involvement in RA (29% of studies). Foot/ankle pain was the outcome domain most commonly measured (78% of studies), being the most frequently specified outcome domain across all RMDs. There was considerable heterogeneity in the other outcome domains measured, across core areas of manifestations (signs, symptoms, biomarkers), life impact, and societal/resource use. The group's progress to date, including findings from the scoping review, was presented and discussed during a virtual OMERACT Special Interest Group (SIG) in October 2022. During this meeting, feedback was sought amongst delegates regarding the scope of the core outcome set, and feedback was received on the next steps of the project, including focus group and Delphi methods.

CONCLUSION

Findings from the scoping review and feedback from the SIG will contribute to the development of a core outcome set for foot and ankle disorders in RMDs. The next steps are to determine which outcome domains are important to patients, followed by a Delphi exercise with key stakeholders to prioritise outcome domains.

The Management of Metatarsalgia in Rheumatoid Arthritis Using Simple Insoles: An Effective Concurrent Treatment to Drug Therapy

BACKGROUND

Metatarsalgia is a common affliction in rheumatoid arthritis (RA), often requiring aggressive pharmacologic treatment that carries associated adverse effects. The aim of this study was to investigate whether simple insoles would have a beneficial effect on forefoot pain, disability, and functional limitation in participants with RA experiencing forefoot pain.

METHOD

A prospective, quasi-experimental, pretest-posttest trial was performed at a rheumatology outpatient clinic. Participants were supplied with a simple insole comprising a valgus pad and a plantar metatarsal pad and covered with a cushioning material. The Foot Function Index (FFI) was self-administered before and 3 months after insole use.

RESULTS

Reductions in forefoot pain (from 56.78 to 42.97) and total (from 41.64 to 33.54) FFI scores were noted. Statistical significance for this reduction was achieved following the t test (P = .002 and P = .0085, respectively). However, although reductions in mean disability and activity limitation scores were recorded (from 50 to 44.85 and from 18 to 14.57, respectively), these did not reach significance (P = .151 and P = .092, respectively) Conclusions: Simple insoles have been shown to be effective in reducing total and forefoot pain FFI scores in patients with RA experiencing metatarsalgia. This treatment offers advantages because these devices can be fabricated simply and cheaply, thus initiating the patient on an effective orthosis therapy immediately in the clinic without having to wait for prolonged periods until custom orthotic devices can be supplied.

Comparison of the Forefoot Pressure-Relieving Effects of Foot Orthoses

PURPOSE

Metatarsal pads are prescribed to decrease forefoot plantar pressure. However, the appropriate metatarsal pad placement location remains a debated issue. We aimed to identify the most effective insole design that reduces forefoot plantar pressure and determine the optimal position for metatarsal pad placement.

MATERIALS AND METHODS

We recruited 16 healthy adult volunteers, and measured their plantar pressure data during walking while using an in-shoe system. The volunteers were randomly assigned to one of four insole conditions: 1/16-inch insole (i.e., control), 1/4-inch soft plastazote (SP) flat insole, metatarsal pad positioned proximal to the metatarsal head (MTH) on the control insole (P0), and metatarsal pad positioned 10 mm distal from the proximal border of the MTH on the control insole (P10). A masking protocol was created by dividing the forefoot into three subareas, distal to the MTH (dMTH), beneath to the MTH (bMTH), and proximal to the MTH (pMTH). The participants reported their comfort level for each insole using a visual analog scale.

RESULTS

The SP flat insole and metatarsal pads both had a forefoot plantar pressure-reducing effect and provided insole comfort. Of the three insole designs, the SP flat insole was the most effective. No clear difference existed in efficacy in terms of the location of the metatarsal pad placement.

CONCLUSION

Considering the possibility of discomfort caused by improper metatarsal pad placement, the SP that increases shock absorption may be more clinically useful.

Orthetik bei rheumatologischen Erkrankungen

Die Versorgung von Patienten mit körpernahen Hilfsmitteln wie Orthesen, Bandagen oder Tapes stellt einen wichtigen Pfeiler der konservativen Maßnahmen der Versorgung von rheumatologischen Erkrankungen dar. Ziel ist es dabei stets schmerzauslösende Belastungen zu reduzieren sowie durch Destruktion instabile Gelenke zu stabilisieren um somit die Funktionsfähigkeit im Alltag so gut es geht aufrecht zu erhalten. Die Teilhabe an täglichen Arbeiten kann dadurch oftmals verbessert werden, was sich konsekutiv auf die Lebensqualität auswirkt. In diesem Beitrag soll die Systematik von verordnungsfähigen Orthesen erklärt werden und anschließend darauf aufbauend für wichtige, oftmals betroffene Gelenke Stabilisationsmöglichkeiten aufgezeigt werden. Die Evidenz und die Verordnungsweise werden dabei wenn möglich aufgezeigt.

The effect of pre-fabricated insole on plantar pressure distribution in patients with rheumatoid arthritis

BACKGROUND

Foot deformities result in pain and changes in plantar pressure distribution in rheumatoid arthritis (RA) patients. Medical insoles are commonly prescribed for declining pain and modifying foot pressure distribution in these patients. The purpose of this study was to evaluate the effect of a pre-fabricated insole with metatarsal pad and medial longitudinal arch support on plantar pressure distribution in rheumatoid arthritis patients.

METHODS

Fifteen females with RA participated in this study. All patients received a pair of pre-fabricated insoles that were individually modified using metatarsal pads and medial longitudinal arch supports. Mean peak pressure (kPa), maximum force (N), and contact area (cm²) were calculated for the heel, midfoot, metatarsophalangeal joint, and toe regions using the Pedar-X system immediately and after a month follow-up.

FINDINGS

In the heel and metatarsophalangeal joint regions, maximum pressure and force showed a significant reduction in the follow-up assessment (p < 0.05). The comparison showed a significant increase in maximum pressure and force in the midfoot when participants walked with insole compared to without insole condition (p < 0.001).

INTERPRETATION

Using a pre-fabricated insole with an individually modified metatarsal pad and medial longitudinal arch support could alter rheumatoid arthritis patients' plantar pressures after one month of follow-up. This type of insole is simple and inexpensive and showed a significant effect on decreasing pressures under the metatarsal heads.

Outcomes and potential mechanism of a protocol to optimize foot orthoses in patients with rheumatoid arthritis

Background

Foot problems are highly prevalent in patients with rheumatoid arthritis. Treatment of foot problems related to rheumatoid arthritis often consists of custom made foot orthoses. One of the assumed working mechanisms of foot orthoses is redistribution of plantar pressure by creating a larger weight bearing area. Overall, the reported treatment effect of foot orthoses on foot pain in rheumatoid arthritis is small to medium. Therefore, we developed a foot orthoses optimization protocol for evaluation and adaptation of foot orthoses by using the feedback of in-shoe plantar pressure measurements. The objectives of the present study were: 1) to evaluate the 3-months outcomes of foot orthoses developed according to the protocol on pain, physical functioning and forefoot plantar pressure in patients with foot problems related to rheumatoid arthritis, and 2) to determine the relationship between change in forefoot plantar pressure and change in pain and physical functioning.

Methods

Forty-five patients with foot problems related to rheumatoid arthritis were included and received foot orthoses developed according to the protocol. Outcome measures were assessed at baseline and after three months of wearing foot orthoses in 38 patients. Change scores and effect sizes (ES) were calculated for pain, physical functioning and plantar pressure. In a subgroup of patients with combined forefoot pain and high plantar pressure, the relationship between change in plantar pressure and change in pain and physical functioning was analyzed.

Results

In the total group of 38 patients, statistically significant changes in pain (ES 0.69), physical functioning (ES 0.82) and forefoot plantar pressure (ES 0.35) were found. In the subgroup (n = 23) no statistically significant relationships were found between change in plantar pressure and change in pain or physical functioning.

Conclusion

Foot orthoses developed according to a protocol for improving the plantar pressure redistribution properties lead to medium to large improvements in pain and physical functioning. The hypothesis that more pressure reduction would lead to better clinical outcomes could not be proven.

Foot Plantar Pressure Measurement System Using Highly Sensitive Crack-Based Sensor

Measuring the foot plantar pressure has the potential to be an important tool in many areas such as enhancing sports performance, diagnosing diseases, and rehabilitation. In general, the plantar pressure sensor should have robustness, durability, and high repeatability, as it should measure the pressure due to body weight. Here, we present a novel insole foot plantar pressure sensor using a highly sensitive crack-based strain sensor. The sensor is made of elastomer, stainless steel, a crack-based sensor, and a 3D-printed frame. Insoles are made of elastomer with Shore A 40, which is used as part of the sensor, to distribute the load to the sensor. The 3D-printed frame and stainless steel prevent breakage of the crack-based sensor and enable elastic behavior. The sensor response is highly repeatable and shows excellent durability even after 20,000 cycles. We show that the insole pressure sensor can be used as a real-time monitoring system using the pressure visualization program.

Systematic review on the comparative effectiveness of foot orthoses in patients with rheumatoid arthritis

Background

Foot orthoses (FOs) are prescribed as an important conservative treatment option in patients with foot problems related to rheumatoid arthritis. However, a broad variation in FOs is used, both in clinical practice and in research. To date, there is no overview on the outcomes of the treatment with different kinds of FOs in patients with rheumatoid arthritis and a specific foot problem. The objectives of the present study were to summarize the comparative effectiveness of FOs in the treatment of various foot problems in patients with rheumatoid arthritis, on the primary outcomes foot function and foot pain, and the secondary outcomes physical functioning, health related quality of life, compliance, adverse events, the costs of FOs and patient satisfaction.

Methods

Studies comparing different kinds of FOs, with a presumed therapeutic effect, in the treatment of foot problems related to rheumatoid arthritis were included. A literature search was conducted in The Cochrane Central Registry for Controlled Trials (CENTRAL), PubMed, EMBASE and PEDro up to May 18th, 2018. Data was meta-analyzed, when this was not possible qualitative data analysis was performed.

Results

Ten studies were identified, with a total number of 235 patients. These studies made a comparison between different materials used (soft versus semi-rigid), types of FOs (custom-made versus ready-made; total-contact versus non-total contact), or modifications applied (metatarsal bars versus domes). Also, different techniques to construct custom-made FOs were compared (standard custom-molding techniques versus more sophisticated techniques). A medium effect for (immediate) reduction of forefoot plantar pressure was found in favor of treatment with soft FOs compared to semi-rigid FOs (SMD 0.60, 95% CI 0.07-1.14; P = 0.03; 28 participants). Other comparisons between FOs resulted in non-significant effects or inconclusive evidence for one kind of FOs over the other.

Conclusions

Foot orthoses made of soft materials may lead to more (immediate) forefoot plantar pressure reduction compared to foot orthoses constructed of semi-rigid materials. Definitive high quality RCTs, with adequate sample sizes and long-term follow-up, are needed to investigate the comparative (cost-) effectiveness of different kinds of foot orthoses for the treatment of foot problems related to rheumatoid arthritis.

Quantifying the effectiveness of static and dynamic insoles in reducing the tibial shock experienced during walking

Many individuals work in jobs that require them to spend much of their day walking. There is evidence to suggest that shoe insoles may reduce the lower extremity discomfort for these workers. This study compared the effects of static and dynamic shoe insoles on lower extremity forces when walking at different speeds. Tibial acceleration (a.k.a. tibial shock) was assessed bilaterally in 30 participants who walked in both athletic shoes and work boots without any additional insole, with additional static insoles, and with additional dynamic insoles. The participants walked a prescribed course at a "slow", "normal", and "fast" pace. With both shoe types, there were significant reductions in tibial shock values when insoles were used. With the work boots, the dynamic insole further reduced tibial shock relative to the static insole. The significant interactions show that the differences between insole conditions become greater with faster walking speeds.

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

BACKGROUND

The 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.

METHODS

A 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.

RESULTS

115 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.

CONCLUSIONS

At 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.

Clinical effectiveness and cost-effectiveness of foot orthoses for people with established rheumatoid arthritis: an exploratory clinical trial

OBJECTIVES

Foot orthoses are commonly prescribed as an intervention for people with rheumatoid arthritis (RA). Data relating to the cost-effectiveness of foot orthoses in people with RA are limited. The aim was to evaluate the clinical and cost-effectiveness of two types of foot orthoses in people with established RA.

METHOD

A single-blind randomized controlled trial was undertaken to compare custom-made foot orthoses (CMFOs) and simple insoles (SIs) in 41 people with established RA. The Foot Function Index (FFI) was used to measure foot pain, disability, and functional limitation. Costs were estimated from the perspective of the UK National Health Service (NHS), societal (patient and family) perspective, and secondary care resource use in terms of the intervention and staff time. Effects were assessed in terms of health gain expressed as quality-adjusted life years (QALYs).

RESULTS

At baseline, 20 participants received a CMFO and 21 participants received an SI. After 16 weeks foot pain improved in both the CMFOs (p = 0.000) and the SIs (p < 0.01). However, disability scores improved for CMFOs (p < 0.001) but not for SIs (p = 0.40). The cost-effectiveness results demonstrated no difference in cost between the arms (CMFOs: £159.10; SIs: £79.10; p = 0.35), with the CMFOs being less effective in terms of cost per QALY gain (p < 0.001).

CONCLUSIONS

In people with established RA, semi-rigid customized foot orthoses can improve pain and disability scores in comparison to simple insoles. From a cost-effectiveness perspective, the customized foot orthoses were far more expensive to manufacture, with no significant cost per QALY gain.

[Orthopedic shoe treatment: Inserts]

The use of inserts and orthopedic shoe adjustment represents an essential component of the conservative therapy of degenerative diseases and deformities of the musculoskeletal system. Inserts can have supportive, bedding and corrective effects and are used in particular for complaints of the feet and ankles. The combination of diverse materials allows a high level of cushioning and supporting features and corresponding longevity to be accomplished. The production is carried out on an individual basis and if necessary computer-assisted in order to achieve an optimal fit. For severe and rigid deformities the formation of pressure ulcers can be prevented by orthopedic shoe adjustment and by the use of orthopedic tailor-made shoes.

Parametric study of orthopedic insole of valgus foot on partial foot amputation

Orthopedic insole was important for partial foot amputation (PFA) to achieve foot balance and avoid foot deformity. The inapposite insole orthosis was thought to be one of the risk factors of reamputation for foot valgus patient, but biomechanical effects of internal tissues on valgus foot had not been clearly addressed. In this study, plantar pressure on heel and metatarsal regions of PFA was measured using F-Scan. The three-dimensional finite element (FE) model of partial foot evaluated different medial wedge angles (MWAs) (0.0°-10.0°) of orthopedic insole on valgus foot. The effect of orthopedic insole on the internal bone stress, the medial ligament tension of ankle, plantar fascia tension, and plantar pressure was investigated. Plantar pressure on medial heel region was about 2.5 times higher than that of lateral region based on the F-Scan measurements. FE-predicted results showed that the tension of medial ankle ligaments was the lowest, and the plantar pressure was redistributed around the heel, the first metatarsal, and the lateral longitudinal arch regions when MWA of orthopedic insole ranged from 7.5° to 8.0°. The plantar fascias maintained about 3.5% of the total load bearing on foot. However, the internal stresses from foot bones increased. The simulation in this study would provide the suggestion of guiding optimal design of orthopedic insole and therapeutic planning to pedorthist.

Use of custom insoles for redistributing plantar pressure, decreasing musculoskeletal pain and reducing postural changes in obese adults

Introduction Insoles are used for different purposes and they can be an additional factor aiding weight loss in obese people due to their contribution in reducing musculoskeletal pain. Objective The aim of the present study was to assess the effect of custom insoles for redistributing plantar pressure, decreasing musculoskeletal pain and reducing postural changes in obese adults. Materials and methods Data was obtained from morbidly obese people, who had a Body Mass Index (BMI) ≥ 35 and < 45 kg/m2, at three moments: before the insole was provided, immediately after insole use began and after two months of use. Anthropometric, postural, musculoskeletal pain and computerized baropodometry data were collected. Results When comparing the stages before the use of the insole and after two months of use, significant (p < 0.05) decreases were observed in the number of people with right lateral postural misalignment, in the intensity of the musculoskeletal pain of the body segments evaluated (except for the right knee), and in the mean of the peak plantar pressure values. In terms of total plantar contact area, the mean increased significantly (p < 0.05) in both right and left feet after the intervention. Conclusion This study demonstrated that the daily use of proprioceptive insoles contributed to reducing peak plantar pressure, musculoskeletal pain and lateral postural deviations. The use of proprioceptive insoles may be an important strategy to encourage obese people to exercise and, consequently, reduce weight.

Dynamic plantar loading index detects altered foot function in individuals with rheumatoid arthritis but not changes due to orthotic use

BACKGROUND

Altered foot function is common in individuals with rheumatoid arthritis. Plantar pressure distributions during gait are regularly assessed in this patient group; however, the association between frequently reported magnitude-based pressure variables and clinical outcomes has not been clearly established. Recently, a novel approach to the analysis of plantar pressure distributions throughout stance phase, the dynamic plantar loading index, has been proposed. This study aimed to assess the utility of this index for measuring foot function in individuals with rheumatoid arthritis.

METHODS

Barefoot plantar pressures during gait were measured in 63 patients with rheumatoid arthritis and 51 matched controls. Additionally, 15 individuals with rheumatoid arthritis had in-shoe plantar pressures measured whilst walking in standardized footwear for two conditions: shoes-only; and shoes with prescribed custom foot orthoses. The dynamic plantar loading index was determined for all participants and conditions. Patient and control groups were compared for significant differences as were the shod and orthosis conditions.

FINDINGS

The patient group was found to have a mean index of 0.19, significantly lower than the control group's index of 0.32 (p>0.001, 95% CI [0.054, 0.197]). No significant differences were found between the shoe-only and shoe plus orthosis conditions. The loading index was found to correlate with clinical measures of structural deformity.

INTERPRETATION

The dynamic plantar loading index may be a useful tool for researchers and clinicians looking to objectively assess dynamic foot function in patients with rheumatoid arthritis; however, it may be unresponsive to changes caused by orthotic interventions in this patient group.

Plantar pressure analysis of accommodative insole in older people with metatarsalgia

Foot pain frequently reduces physical activity and increases the risk of falls in older people. In current orthotic management of forefoot pain, metatarsal padding is the main strategy to reduce metatarsal pressure. However, pressure reductions are usually diverse and limited. The multi-step accommodative insole is fabricated by sequential foam padding on Plastazote under dynamic accommodation in daily walking. The aims of this study were to investigate the effectiveness and mechanisms of accommodative insole on plantar pressure redistribution in older people with metatarsalgia. The study was conducted on 21 old outpatients with moderate to severe metatarsalgia, using the ethylene vinyl acetate control, 9-mm flat Plastazote, and accommodative insoles with and without metatarsal and arch support. Outcome measures included pressure-related variables measured by a Pedar-X system, and pain scores assessed with a 0-10 Visual Analog Scale. The accommodative insole significantly decreased peak pressure under the metatarsal heads by 47.2% (p<0.001) and the pain scores from 8.2 to 1.1 (p<0.001). Plantar pressure analyses indicated that the effects of dynamic metatarsal contouring and cushioning on reducing peak pressure were greater than those of metatarsal padding. The temporo-spatial relationships between the toe and metatarsal head can assist in explaining an elevated metatarsal pressure and higher risk of falls in older people with toe deformities. The multi-step insole is simple in orthotic fabrication and ensures an even distribution of plantar pressure loading in walking. It can effectively relieve metatarsalgia and help to preserve regular walking activity for older people with metatarsalgia.

Dose-response effects of customised foot orthoses on lower limb muscle activity and plantar pressures in pronated foot type

Customised foot orthoses (FOs) featuring extrinsic rearfoot posting are commonly prescribed for individuals with a symptomatic pronated foot type. By altering the angle of the posting it is purported that a controlled dose-response effect during the stance phase of gait can be achieved, however these biomechanical changes have yet to be characterised. Customised FOs were administered to participant groups with symptomatic pronated foot types and asymptomatic normal foot types. The electromyographic (EMG) and plantar pressure effects of varying the dose were measured. Dose was varied by changing the angle of posting from 6° lateral to 10° medial in 2° steps on customised devices produced using computer aided orthoses design software. No effects due to posting level were found for EMG variables. Significant group effects were seen with customised FOs reducing above knee muscle activity in pronated foot types compared to normal foot types (biceps femoris p=0.022; vastus lateralis p<0.001; vastus medialis p=0.001). Interaction effects were seen for gastrocnemius medialis and soleus. Significant linear effects of posting level were seen for plantar pressure at the lateral rearfoot (p=0.001), midfoot (p<0.001) and lateral forefoot (p=0.002). A group effect was also seen for plantar pressure at the medial heel (p=0.009). This study provides evidence that a customised FOs can provide a dose response effect for selected plantar pressure variables, but no such effect could be identified for muscle activity. Foot type may play an important role in the effect of customised orthoses on activity of muscles above the knee.