The effect of foot orthoses on gait biomechanics and pain among people with rheumatoid arthritis: A quasi-experimental study.

BACKGROUND: Foot pain is frequent among people with rheumatoid arthritis (RA). Foot orthoses (FO) are commonly prescribed with the intention to reduce pain symptoms and improve function. RESEARCH QUESTION: How do a custom-made FO affect pain, gait biomechanics and daily activity among people with RA? METHODS: Twenty-five participants with RA and foot pain completed this quasi-experimental study using a control insole for four weeks and then a custom-made FO in the following four weeks. The foot orthoses were customized by plantar foot shape targeting optimal restoration of normal arch height. A visual analog scale was used to monitor changes in ankle/foot, knee, hip joints, and global arthritis pain. In addition, the perceived pain area was measured using a body chart analysis. Kinematics and kinetics of the hip, knee and ankle joints during gait were analyzed using 3D-motion capture. Daily steps were measured with a wrist-based activity tracker for both the control insole and custom-made FO period, respectively. RESULTS: In comparison to the control insole, the custom-made FO reduced ankle/foot pain intensity (p < 0.001) in addition to a reduction of the perceived pain areas in the feet (p < 0.001), legs (p = 0.012), as well as the arms and hands (p = 0.014). Ankle plantar flexion and eversion moments were also reduced (p < 0.001). No difference in daily steps was observed between the two periods (p = 0.657). SIGNIFICANCE: This study has demonstrated an ankle/foot pain-relieving effect in conjunction with alterations of the ankle joint moments in people with RA using custom-made FO. The pain relief is plausibly attributed to alterations of the ankle joint moments when using the custom-made FO. However, future studies are needed to explore further into therapeutic implication of custom-made FO in pain management of people with RA.

Different types of foot orthoses effect on gait mechanics in patients with rheumatoid arthritis.

Foot orthoses are a first line conservative treatment for foot impairments in patients with rheumatoid arthritis (RA), however their effect on gait mechanics is poorly understood. We aimed to compare changes in lower limb and foot mechanics between two types of commonly used foot orthoses (FO) with a control. Twenty-seven patients with rheumatoid arthritis participated in this crossover study. Two different types of FO (a medially wedged custom-made FO and a prefabricated FO with a metatarsal dome, respectively), were compared against a control insole. During gait, lower limb mechanics were analyzed using 3D motion capture, force plates, and an in-shoe pressure system. Inverse dynamics models were created in the Anybody Modeling System to calculate joint angles and joint moments during gait. Gait variables were analyzed using statistical parametric mapping. Compared to the control, the prefabricated FO had limited effect on gait mechanics. Compared to the control the custom-made FO reduced ankle plantarflexion moment with 0.4 %body weight * body height (BW * BH) between 66 and 76% of stance and ankle eversion moment was reduced 0.16% BW*BH between 3 and 40% of stance. Furthermore, it also reduced the average forefoot plantar pressure by 9 kPa between 20 and 62% of stance compared to the control. Changes in foot pressure distribution, joint moments and angles were most pronounced for custom-made FO compared to the prefabricated FO. The findings suggest that patients with RA and foot impairments may benefit more from an individualized FO strategy, if the aim of the treatment is to alter gait mechanics. (NCT03561688).

Plantar soft tissues and Achilles tendon thickness and stiffness in people with diabetes: a systematic review.

BACKGROUND: Diabetes mellitus is associated with changes in soft tissue structure and function. However, the directionality of this change and the extent to which either tissue thickness or stiffness contributes to the pathogenesis of diabetes-related foot ulcerations is unclear. Hence, this systematic review aims to summarise the existing evidence for soft tissue structural differences in the feet of people with and without diabetes. METHODS: In compliance with MOOSE and PRISMA guidelines, AMED, CINAHL, MEDLINE, ProQuest Health & Medical Collection, ProQuest Nursing & Allied Health Database, and Web of Science electronic databases were systematically searched for studies published from database inception until 1st October 2020 [Prospero CRD42020166614]. Reference lists of included studies were further screened. Methodological quality was appraised using a modified critical appraisal tool for quantitative studies developed by McMaster University. RESULTS: A total of 35 non-randomised observational studies were suitable for inclusion. Within these, 20 studies evaluated plantar tissue thickness, 19 studies evaluated plantar tissue stiffness, 9 studies evaluated Achilles tendon thickness and 5 studies evaluated Achilles tendon stiffness outcomes. No significant differences in plantar tissue thickness were found between people with and without diabetes in 55% of studies (11/20), while significantly increased plantar tissue stiffness was found in people with diabetes in 47% of studies (9/19). Significantly increased Achilles tendon thickness was found in people with diabetes in 44% of studies (4/9), while no significant differences in Achilles tendon stiffness were found between people with and without diabetes in 60% of studies (3/5). CONCLUSIONS: This systematic review found some evidence of soft tissue structural differences between people with and without diabetes. However, uncertainty remains whether these differences independently contribute to diabetes-related foot ulcerations. The heterogeneity of methodological approaches made it difficult to compare across studies and methodological quality was generally inadequate. High-quality studies using standardised and validated assessment techniques in well-defined populations are required to determine more fully the role of structural tissue properties in the pathogenesis of diabetes-related foot ulcerations.

Association of peripheral artery disease and chronic limb-threatening ischemia with socioeconomic deprivation in people with diabetes: A population data-linkage and geospatial analysis.

The association between the prevalence and geographical distribution of peripheral artery disease (PAD) and chronic limb-threatening ischemia (CLTI) in patients with diabetes in the context of socioeconomic deprivation is not well understood. We undertook a retrospective cohort study of 76,307 people with diabetes admitted as a hospital inpatient in a large Scottish health administrative area. Utilising linked health records, we identified diagnoses of PAD and/or CLTI and their distribution using small area cartography techniques according to multiple deprivation maps. Spatial autocorrelation techniques were applied to examine PAD and CLTI patterning. Association between crude inpatient prevalence-adjusted outcome rates and exposure to social deprivation were determined. We found crude prevalence-adjusted rates of 8.05% for PAD and 1.10% for CLTI with a five- to sevenfold difference from the least to most deprived regions. Statistically significant hot spots were found for PAD (p < 0.001) and CLTI (p < 0.001) in the most deprived areas, and cold spots for PAD (p < 0.001) but not CLTI (p = 0.72) in the least deprived areas. Major health disparities in PAD/CLTI diagnoses in people with diabetes is driven by socioeconomic deprivation.

Measuring Inflammatory Foot Disease in Rheumatoid Arthritis: Development and Validation of the Rheumatoid Arthritis Foot Disease Activity Index-5.

OBJECTIVE: Omission of foot joints from composite global disease activity indices may lead to underestimation of foot and overall disease in rheumatoid arthritis (RA) and under-treatment. The aim of this study was to evaluate the measurement properties of the Rheumatoid Arthritis Foot Disease Activity Index-5 (RADAI-F5), a newly developed patient-reported outcome measure for capturing foot disease activity in people with RA. METHODS: Participants with RA self-completed the RADAI-F5, modified Rheumatoid Arthritis Disease Activity Index (mRADAI-5), Foot Function Index (FFI), and Foot Impact Scale (FIS) impairment/footwear and activity/participation subscales. The 28-joint Disease Activity Score using the erythrocyte sedimentation rate (DAS28-ESR) was also recorded. Subgroups completed the RADAI-F5 at 1 week and 6 months. Psychometric properties, including construct, content and longitudinal validity, internal consistency, 1-week reproducibility, and responsiveness over 6 months were evaluated. RESULTS: Of 142 respondents, 103 were female, with a mean ± SD age of 55 ± 12.5 years and median RA disease duration of 10 (interquartile range 3.6-20.8) months. Theoretically consistent associations confirming construct validity were observed with mRADAI-5 (0.789 [95% confidence interval (95% CI) 0.73, 0.85]), FFI (0.713 [95% CI 0.62, 0.79]), FIS impairment/footwear (0.695 [95% CI 0.66, 0.82], P < 0.001), FIS activity/participation (0.478 [95% CI 0.37, 0.63], P < 0.001), and the DAS28-ESR (0.379 [95% CI 0.26, 0.57], P < 0.001). The RADAI-F5 demonstrated high internal consistency (Cronbach's α = 0.90) and good reproducibility (intraclass correlation coefficient = 0.868 [95% CI 0.80, 0.91], P < 0.001, smallest detectable change = 2.69). Content validity was confirmed, with 82% rating the instrument relevant and easy to understand. CONCLUSION: The RADAI-F5 is a valid, reliable, responsive, clinically feasible patient-reported outcome measure for measuring foot disease activity in RA.

Sex- and osteoarthritis-related differences in muscle co-activation during weight-bearing tasks.

BACKGROUND: Individuals with knee osteoarthritis (OA) demonstrate impairments in muscle function (i.e. muscle weakness, high muscle co-activation believed to have detrimental effects on joint integrity). Women with knee OA exhibit poorer health outcomes than men. Sex and muscle function are known risk factors for knee OA. It is unclear how these risk factors are associated with muscle function in knee OA and the implications for disease aetiology. RESEARCH QUESTION: How does sex and knee osteoarthritis disease status relate to muscle function, specifically strength and muscle co-activation, during walking, stair negotiation and sit-to-walk activities. METHODS: A cross-sectional study assessed muscle co-activation in 77 individuals with knee OA (mean[SD], 62.5[8.1] years; 48/29 women/men) and 18 age-matched controls (62.5[10.4] years; 9/9 women/men), during a series of walking, stair ascent and descent and sit-to-walk activities. Muscle strength of the knee extensors and flexors was assessed using maximal voluntary isometric contractions (MVIC). Electromyography was recorded from the vastus lateralis/medalis, rectus femoris, biceps femoris, semitendinosus, medial/lateral gastrocnemius normalised to MVIC. Multiple regression assessed the relationship between sex, disease status, and muscle strength on muscle co-activation. RESULTS: Individuals with knee OA were weaker than controls, had higher hamstrings-quadriceps and medial-lateral co-activation for specific phases of gait. Women were weaker than men with higher muscle co-activation across all activities. Sex and muscle weakness, but not age or disease status predicted high muscle co-activation. SIGNIFICANCE: High muscle co-activation was associated with female sex and muscle weakness regardless of disease status and age. High muscle co-activation is believed to be a compensatory mechanism for muscle weakness to maintain a certain level of function. High muscle co-activation is also thought to have detrimental effects on cartilage and joint integrity this may explain high muscle co-activation in women with muscle weakness and contribute to increased risk of incidence and progression of knee OA in women.

The future for diabetic foot ulcer prevention: A paradigm shift from stratified healthcare towards personalized medicine.

Prevention of diabetic foot ulcers is important to reduce the burden of diabetic foot disease. However, we found that ulcer prevention is underexposed in research and clinical practice. Barriers to explain this are seen in patient's goal-setting; in the lack of interdisciplinary teams for ulcer prevention; in sample sizes and funding for research; in industrial engagement; and in limited understanding of ulcer development. Rather than separately solving these barriers, we propose a paradigm shift from stratified healthcare towards personalized medicine for diabetic foot disease. Personalized medicine aims to deliver the right treatment to the right patient at the right time, based on individual diagnostics. Different treatment strategies should be available for different patients, delivered in an integrated, objective, quantitative and evidence-based approach. More than on the classical risk factors of peripheral neuropathy and peripheral artery disease, individual diagnostics should focus on modifiable risk factors for ulceration. This includes structured biomechanical and behavioral profiling, while new research with (big) data science may identify additional risk factors, such as geographical or temporal patterns in ulceration. Industry involvement can drive the development of wearable instruments and assessment tools, to facilitate large-scale individual diagnostics. For a paradigm shift towards personalized medicine in prevention, large-scale collaborations between stakeholders are needed. As each ulcer episode not prevented costs about €10,000 in medical costs alone, such investments can be cost-effective. We hope to see more discussions around this paradigm shift, and increasing investments of energy and money in diabetic foot ulcer prevention in research and clinical practice.

Geospatial mapping and data linkage uncovers variability in outcomes of foot disease according to multiple deprivation: a population cohort study of people with diabetes.

AIMS/HYPOTHESIS: Our aim was to investigate the geospatial distribution of diabetic foot ulceration (DFU), lower extremity amputation (LEA) and mortality rates in people with diabetes in small geographical areas with varying levels of multiple deprivation. METHODS: We undertook a population cohort study to extract the health records of 112,231 people with diabetes from the Scottish Care Information - Diabetes Collaboration (SCI-Diabetes) database. We linked this to health records to identify death, LEA and DFU events. These events were geospatially mapped using multiple deprivation maps for the geographical area of National Health Service (NHS) Greater Glasgow and Clyde. Tests of spatial autocorrelation and association were conducted to evaluate geographical variation and patterning, and the association between prevalence-adjusted outcome rates and multiple deprivation by quintile. RESULTS: Within our health board region, people with diabetes had crude prevalence-adjusted rates for DFU of 4.6% and for LEA of 1.3%, and an incidence rate of mortality preceded by either a DFU or LEA of 10.5 per 10,000 per year. Spatial autocorrelation identified statistically significant hot spot (high prevalence) and cold spot (low prevalence) clusters for all outcomes. Small-area maps effectively displayed near neighbour clustering across the health board geography. Disproportionately high numbers of hot spots within the most deprived quintile for DFU (p < 0.001), LEA (p < 0.001) and mortality (p < 0.001) rates were found. Conversely, a disproportionately higher number of cold spots was found within the least deprived quintile for LEA (p < 0.001). CONCLUSIONS/INTERPRETATION: In people with diabetes, DFU, LEA and mortality rates are associated with multiple deprivation and form geographical neighbourhood clusters.

Muscle Co-Activation Across Activities of Daily Living in Individuals With Knee Osteoarthritis.

OBJECTIVE: Muscle co-activation has been shown to be elevated in individuals with knee osteoarthritis (OA) during gait. Comparisons of muscle co-activation across different activities of daily living such as stair negotiation have yet to be explored. The aim of this study was to explore muscle co-activation across different activities of daily living in patients with knee OA. METHODS: Muscle co-activation was assessed in 77 symptomatic knee OA patients (mean ± SD age 62.5 ± 8.1 years, body mass index 29.4 ± 6.0 kg/m2 , and sex 48:29 female:male) using electromyography (EMG), during a series of walking, stair negotiation (ascent, descent), and sit-to-walk activities. EMG was recorded from 7 sites, mediolateral gastrocnemius, biceps femoris, semitendinosus, vastus lateralis/medialis, and rectus femoris, and normalized to maximal voluntary isometric contraction. Correlation was used to assess the consistency of co-activation across activities. Repeated-measures analysis of variance assessed the muscle combination by activity differences. RESULTS: Muscle co-activation was highest during stair ascent. When comparing muscle combinations within the same activity, we found that correlations ranged from r = 0.003 to r = 0.897, of which 80% of the combinations were significant. Between activities, muscle co-activation was significantly different (P < 0.05). Mediolateral muscle co-activation was higher than hamstrings/quadriceps across activities. CONCLUSION: Two muscle co-activation strategies were observed during activities of daily living in patients with knee OA to maintain stability. Muscle co-activation was higher during more challenging activities, particularly when the joint was accepting load. Mediolateral muscle co-activation was higher than hamstrings/quadriceps, so that mediolateral co-activation was thought to be a stabilization mechanism, while hamstrings/quadriceps co-activation responds to knee flexion moments, suggesting that different muscle combinations may have different roles in responding to joint demand.

The immediate effect of a soft knee brace on pain, activity limitations, self-reported knee instability, and self-reported knee confidence in patients with knee osteoarthritis.

BACKGROUND: We aimed to (i) evaluate the immediate effect of a soft knee brace on pain, activity limitations, self-reported knee instability, and self-reported knee confidence, and (ii) to assess the difference in effect between a non-tight and a tight soft brace in patients with knee osteoarthritis (OA). METHODS: Forty-four patients with knee OA and self-reported knee instability participated in the single-session, laboratory, experimental study. A within-subject design was used, comparing a soft brace with no brace, and comparing a non-tight with a tight soft brace. The outcome measures were pain, self-reported knee instability and knee confidence during level and perturbed walking on the treadmill and activity limitations (10-m walk test and the get up and go (GUG) test). Linear mixed-effect model analysis for continuous outcomes and logistic generalized estimating equations for categorical outcomes were used to evaluate the effect of wearing a soft brace. RESULTS: Wearing a soft brace significantly reduced pain during level walking (B - 0.60, P = 0.001) and perturbed walking (B - 0.80, P < 0.001), reduced the time to complete the 10-m walk (B - 0.23, P < 0.001) and the GUG tests (B - 0.23, P = 0.004), reduced self-reported knee instability during level walking (OR 0.41, P = 0.002) and perturbed walking (OR 0.36, P < 0.001), and reduced lack of confidence in the knees during level walking (OR 0.45, P < 0.001) and perturbed walking (OR 0.56, P < 0.001), compared with not wearing a soft brace. There was no difference in effects between a non-tight and tight brace, except for the 10-m walk test. Wearing a tight brace significantly reduced the time to complete the 10-m walk test in comparison with wearing a non-tight brace (B - 0.11, P = 0.03). CONCLUSION: The results of this study indicate that a soft brace is an efficacious intervention targeting pain, activity limitations, self-reported knee instability, and knee confidence in the immediate term in patients with knee OA. Further studies are needed evaluating the mode of action based on exerted pressure, and on the generalization to functioning in daily life. TRIAL REGISTRATION: trialregister.nl, NTR6363 . Retrospectively registered on 15 May 2017.

Prevalence, impact and care of foot problems in people with rheumatoid arthritis: results from a United Kingdom based cross-sectional survey.

BACKGROUND: Foot symptoms in rheumatoid arthritis (RA) derive from a combination of inflammation, altered foot mechanics, deformity and secondary skin lesions. Guidelines recommend regular review of patients' feet, but the extent to which the general population of RA patients report foot symptoms and access foot care has not been established. The aims of this study were to determine the prevalence, impact and care of foot problems in all patients with RA in one geographical area and identify factors associated with accessing foot care. METHODS: Cross-sectional survey of a random sample of patients with RA, who resided within a single community-based National Health Service (NHS) podiatry service. The questionnaire collected demographic data (age, gender, local deprivation score), clinical data (disease duration, arthritis medications, disability (Health Assessment Questionnaire (HAQ)), current foot problems, foot care accessed (podiatry, orthotics and/or orthopaedics) and care received, measures of impact (Foot Impact Scale) and ability to work. RESULTS: Of 1003 total eligible patients in the target population, 739 were posted survey packs. Of these 413 (56%) replied. Responders and non-responders had similar age (63.5 yr. vs.61.5 yr), gender (74.1%F vs. 75.2%F), and highest deprivation category (13.3% vs.15.9%). Of the responders 92.1% reported current foot problems: articular 73.8%, cutaneous lesions 65.4%, structural 57.6%, extra-articular 42.6%. Responders' median (IQR) disease duration 10 (5-20) years, HAQ 1.5 (0.75-2.0), FISIF 10 (6-14) and FISAP 16 (7-23) and 37.8% reported impacts on work. While 69.5% had accessed foot care there were differences in the route of access (by gender and whether independent or NHS provision) and were older (64.9 yr. vs 60.4 yr. p = 0.001), had longer disease duration (12 yr. vs 7 yr. p < 0.001) and had a greater proportion of females (72.2% vs 61.7% p = 0.04) than those who had not accessed care. CONCLUSIONS: Current foot problems were reported by 92.1% of the study sample and substantially impacted on life and work. While overall access to foot care was higher than anticipated, routes of access differed and extent of current problems suggests the provision of effective, timely and targeted care is a pressing need.

Knee joint kinetics in response to multiple three-dimensional printed, customised foot orthoses for the treatment of medial compartment knee osteoarthritis.

The knee adduction moment is consistently used as a surrogate measure of medial compartment loading. Foot orthoses are designed to reduce knee adduction moment via lateral wedging. The 'dose' of wedging required to optimally unload the affected compartment is unknown and variable between individuals. This study explores a personalised approach via three-dimensional printed foot orthotics to assess the biomechanical response when two design variables are altered: orthotic length and lateral wedging. Foot orthoses were created for 10 individuals with symptomatic medial knee osteoarthritis and 10 controls. Computer-aided design software was used to design four full and four three-quarter-length foot orthoses per participant each with lateral posting of 0° 'neutral', 5° rearfoot, 10° rearfoot and 5° forefoot/10° rearfoot. Three-dimensional printers were used to manufacture all foot orthoses. Three-dimensional gait analyses were performed and selected knee kinetics were analysed: first peak knee adduction moment, second peak knee adduction moment, first knee flexion moment and knee adduction moment impulse. Full-length foot orthoses provided greater reductions in first peak knee adduction moment (p = 0.038), second peak knee adduction moment (p = 0.018) and knee adduction moment impulse (p = 0.022) compared to three-quarter-length foot orthoses. Dose effect of lateral wedging was found for first peak knee adduction moment (p < 0.001), second peak knee adduction moment (p < 0.001) and knee adduction moment impulse (p < 0.001) indicating greater unloading for higher wedging angles. Significant interaction effects were found for foot orthosis length and participant group in second peak knee adduction moment (p = 0.028) and knee adduction moment impulse (p = 0.036). Significant interaction effects were found between orthotic length and wedging condition for second peak knee adduction moment (p = 0.002). No significant changes in first knee flexion moment were found. Individual heterogeneous responses to foot orthosis conditions were observed for first peak knee adduction moment, second peak knee adduction moment and knee adduction moment impulse. Biomechanical response is highly variable with personalised foot orthoses. Findings indicate that the tailoring of a personalised intervention could provide an additional benefit over standard interventions and that a three-dimensional printing approach to foot orthosis manufacturing is a viable alternative to the standard methods.

Clinical practice guidelines for the foot and ankle in rheumatoid arthritis: a critical appraisal.

BACKGROUND: Clinical practice guidelines are recommendations systematically developed to assist clinical decision-making and inform healthcare. In current rheumatoid arthritis (RA) guidelines, management of the foot and ankle is under-represented and the quality of recommendation is uncertain. This study aimed to identify and critically appraise clinical practice guidelines for foot and ankle management in RA. METHODS: Guidelines were identified electronically and through hand searching. Search terms 'rheumatoid arthritis', 'clinical practice guidelines' and related synonyms were used. Critical appraisal and quality rating were conducted using the Appraisal of Guidelines for Research and Evaluation (AGREE) II instrument. RESULTS: Twenty-four guidelines were included. Five guidelines were high quality and recommended for use. Five high quality and seven low quality guidelines were recommended for use with modifications. Seven guidelines were low quality and not recommended for use. Five early and twelve established RA guidelines were recommended for use. Only two guidelines were foot and ankle specific. Five recommendation domains were identified in both early and established RA guidelines. These were multidisciplinary team care, foot healthcare access, foot health assessment/review, orthoses/insoles/splints, and therapeutic footwear. Established RA guidelines also had an 'other foot care treatments' domain. CONCLUSIONS: Foot and ankle management for RA features in many clinical practice guidelines recommended for use. Unfortunately, supporting evidence in the guidelines is low quality. Agreement levels are predominantly 'expert opinion' or 'good clinical practice'. More research investigating foot and ankle management for RA is needed prior to inclusion in clinical practice guidelines.

The Glasgow-Maastricht foot model, evaluation of a 26 segment kinematic model of the foot.

BACKGROUND: Accurately measuring of intrinsic foot kinematics using skin mounted markers is difficult, limited in part by the physical dimensions of the foot. Existing kinematic foot models solve this problem by combining multiple bones into idealized rigid segments. This study presents a novel foot model that allows the motion of the 26 bones to be individually estimated via a combination of partial joint constraints and coupling the motion of separate joints using kinematic rhythms. METHODS: Segmented CT data from one healthy subject was used to create a template Glasgow-Maastricht foot model (GM-model). Following this, the template was scaled to produce subject-specific models for five additional healthy participants using a surface scan of the foot and ankle. Forty-three skin mounted markers, mainly positioned around the foot and ankle, were used to capture the stance phase of the right foot of the six healthy participants during walking. The GM-model was then applied to calculate the intrinsic foot kinematics. RESULTS: Distinct motion patterns where found for all joints. The variability in outcome depended on the location of the joint, with reasonable results for sagittal plane motions and poor results for transverse plane motions. CONCLUSIONS: The results of the GM-model were comparable with existing literature, including bone pin studies, with respect to the range of motion, motion pattern and timing of the motion in the studied joints. This novel model is the most complete kinematic model to date. Further evaluation of the model is warranted.

Metatarsal Loading During Gait-A Musculoskeletal Analysis.

Detailed knowledge of the loading conditions within the human body is essential for the development and optimization of treatments for disorders and injuries of the musculoskeletal system. While loads in the major joints of the lower limb have been the subject of extensive study, relatively little is known about the forces applied to the individual bones of the foot. The objective of this study was to use a detailed musculoskeletal model to compute the loads applied to the metatarsal bones during gait across several healthy subjects. Motion-captured gait trials and computed tomography (CT) foot scans from four healthy subjects were used as the inputs to inverse dynamic simulations that allowed the computation of loads at the metatarsal joints. Low loads in the metatarsophalangeal (MTP) joint were predicted before terminal stance, however, increased to an average peak of 1.9 times body weight (BW) before toe-off in the first metatarsal. At the first tarsometatarsal (TMT) joint, loads of up to 1.0 times BW were seen during the early part of stance, reflecting tension in the ligaments and muscles. These loads subsequently increased to an average peak of 3.0 times BW. Loads in the first ray were higher compared to rays 2-5. The joints were primarily loaded in the longitudinal direction of the bone.

Acquired midfoot deformity and function in individuals with diabetes and peripheral neuropathy.

BACKGROUND: Diabetes mellitus related medial column foot deformity is a major contributor to ulceration and amputation. However, little is known about the relationship between medial column alignment and function and the integrity of the soft tissues that support and move the medial column. The purposes of this study were to determine the predictors of medial column alignment and function in people with diabetes and peripheral neuropathy. METHODS: 23 participants with diabetes and neuropathy had radiographs, heel rise kinematics, magnetic resonance imaging and isokinetic muscle testing to measure: 1) medial column alignment (Meary's angle--the angle between the 1st metatarsal longitudinal axis and the talar head and neck), 2) medial column function (forefoot relative to hindfoot plantarflexion during heel rise), 3) intrinsic foot muscle and fat volume, ratio of posterior tibialis to flexor digitorum tendon volume, 4) plantar fascia function (Meary's angle change from toes flat to extended) and 5) plantarflexor peak torque. Predictors of medial column alignment and function were determined using simultaneous entry multiple regression. FINDINGS: Posterior tibialis to flexor digitorum tendon volume ratio and intrinsic foot muscle volume were significant predictors of medial column alignment (P<.05), accounting for 44% of the variance. Intrinsic foot fat volume and plantarflexor peak torque were significant predictors of medial column function (P<.05), accounting for 37% of the variance. INTERPRETATION: Deterioration of medial column supporting structures predicted alignment and function. Prospective research is required to monitor alignment, structure, and function over time to inform early intervention strategies to prevent deformity, ulceration, and amputation.

Simplified versus geometrically accurate models of forefoot anatomy to predict plantar pressures: A finite element study.

Integration of patient-specific biomechanical measurements into the design of therapeutic footwear has been shown to improve clinical outcomes in patients with diabetic foot disease. The addition of numerical simulations intended to optimise intervention design may help to build on these advances, however at present the time and labour required to generate and run personalised models of foot anatomy restrict their routine clinical utility. In this study we developed second-generation personalised simple finite element (FE) models of the forefoot with varying geometric fidelities. Plantar pressure predictions from barefoot, shod, and shod with insole simulations using simplified models were compared to those obtained from CT-based FE models incorporating more detailed representations of bone and tissue geometry. A simplified model including representations of metatarsals based on simple geometric shapes, embedded within a contoured soft tissue block with outer geometry acquired from a 3D surface scan was found to provide pressure predictions closest to the more complex model, with mean differences of 13.3kPa (SD 13.4), 12.52kPa (SD 11.9) and 9.6kPa (SD 9.3) for barefoot, shod, and insole conditions respectively. The simplified model design could be produced in <1h compared to >3h in the case of the more detailed model, and solved on average 24% faster. FE models of the forefoot based on simplified geometric representations of the metatarsal bones and soft tissue surface geometry from 3D surface scans may potentially provide a simulation approach with improved clinical utility, however further validity testing around a range of therapeutic footwear types is required.

Let me Google that for you: a time series analysis of seasonality in internet search trends for terms related to foot and ankle pain.

BACKGROUND: The analysis of internet search traffic may present the opportunity to gain insights into general trends and patterns in information seeking behaviour related to medical conditions at a population level. For prevalent and widespread problems such as foot and ankle pain, this information has the potential to improve our understanding of seasonality and trends within these conditions and their treatments, and may act as a useful proxy for their true incidence/prevalence characteristics. This study aimed to explore seasonal effects, general trends and relative popularity of internet search terms related to foot and ankle pain over the past decade. METHODS: We used the Google Trends tool to obtain relative search engine traffic for terms relating to foot and ankle pain and common treatments from Google search and affiliated pages for major northern and southern hemisphere English speaking nations. Analysis of overall trends and seasonality including summer/winter differences was carried out on these terms. RESULTS: Searches relating to general foot pain were on average 3.4 times more common than those relating to ankle pain, and twice as common as searches relating to heel pain. Distinct seasonal effects were seen in the northern hemisphere, with large increases in search volumes in the summer months compared to winter for foot (p = 0.004, 95 % CI [22.2-32.1]), ankle (p = 0.0078, 95 % CI [20.9-35.5]), and heel pain (p = 0.004, 95 % CI [29.1-45.6]). These seasonal effects were reflected by data from Australia, with the exception of ankle pain. Annual seasonal effects for treatment options were limited to terms related to foot surgery and ankle orthoses (p = 0.031, 95 % CI [3.5-20.9]; p = 0.004, 95 % CI [7.6-25.2] respectively), again increasing in the summer months. CONCLUSIONS: A number of general trends and annual seasonal effects were found in time series internet search data for terms relating to foot and ankle pain. This data may provide insights into these conditions at population levels.

Predictors of barefoot plantar pressure during walking in patients with diabetes, peripheral neuropathy and a history of ulceration.

OBJECTIVE: Elevated dynamic plantar foot pressures significantly increase the risk of foot ulceration in diabetes mellitus. The aim was to determine which factors predict plantar pressures in a population of diabetic patients who are at high-risk of foot ulceration. METHODS: Patients with diabetes, peripheral neuropathy and a history of ulceration were eligible for inclusion in this cross sectional study. Demographic data, foot structure and function, and disease-related factors were recorded and used as potential predictor variables in the analyses. Barefoot peak pressures during walking were calculated for the heel, midfoot, forefoot, lesser toes, and hallux regions. Potential predictors were investigated using multivariate linear regression analyses. 167 participants with mean age of 63 years contributed 329 feet to the analyses. RESULTS: The regression models were able to predict between 6% (heel) and 41% (midfoot) of the variation in peak plantar pressures. The largest contributing factor in the heel model was glycosylated haemoglobin concentration, in the midfoot Charcot deformity, in the forefoot prominent metatarsal heads, in the lesser toes hammer toe deformity and in the hallux previous ulceration. Variables with local effects (e.g. foot deformity) were stronger predictors of plantar pressure than global features (e.g. body mass, age, gender, or diabetes duration). CONCLUSION: The presence of local deformity was the largest contributing factor to barefoot dynamic plantar pressure in high-risk diabetic patients and should therefore be adequately managed to reduce plantar pressure and ulcer risk. However, a significant amount of variance is unexplained by the models, which advocates the quantitative measurement of plantar pressures in the clinical risk assessment of the patient.

What has finite element analysis taught us about diabetic foot disease and its management? A systematic review.

BACKGROUND: Over the past two decades finite element (FE) analysis has become a popular tool for researchers seeking to simulate the biomechanics of the healthy and diabetic foot. The primary aims of these simulations have been to improve our understanding of the foot's complicated mechanical loading in health and disease and to inform interventions designed to prevent plantar ulceration, a major complication of diabetes. This article provides a systematic review and summary of the findings from FE analysis-based computational simulations of the diabetic foot. METHODS: A systematic literature search was carried out and 31 relevant articles were identified covering three primary themes: methodological aspects relevant to modelling the diabetic foot; investigations of the pathomechanics of the diabetic foot; and simulation-based design of interventions to reduce ulceration risk. RESULTS: Methodological studies illustrated appropriate use of FE analysis for simulation of foot mechanics, incorporating nonlinear tissue mechanics, contact and rigid body movements. FE studies of pathomechanics have provided estimates of internal soft tissue stresses, and suggest that such stresses may often be considerably larger than those measured at the plantar surface and are proportionally greater in the diabetic foot compared to controls. FE analysis allowed evaluation of insole performance and development of new insole designs, footwear and corrective surgery to effectively provide intervention strategies. The technique also presents the opportunity to simulate the effect of changes associated with the diabetic foot on non-mechanical factors such as blood supply to local tissues. DISCUSSION: While significant advancement in diabetic foot research has been made possible by the use of FE analysis, translational utility of this powerful tool for routine clinical care at the patient level requires adoption of cost-effective (both in terms of labour and computation) and reliable approaches with clear clinical validity for decision making.