A Review of the Biomechanics of the Diabetic Foot

Advanced multifunctional hydrogels for diabetic foot ulcer healing: Active substances and biological functions

AIM

Hydrogels with excellent biocompatibility and biodegradability can be used as the desirable dressings for the therapy of diabetic foot ulcer (DFU). This review aimed to summarize the biological functions of hydrogels, combining with the pathogenesis of DFU.

METHODS

The studies in the last 10 years were searched and summarized from the online database PubMed using a combination of keywords such as hydrogel and diabetes. The biological functions of hydrogels and their healing mechanism on DFU were elaborated.

RESULTS

In this review, hydrogels were classified by their active substances such as drugs, cytokines, photosensitizers, and biomimetic peptide. Based on this, the biological functions of hydrogels were summarized by associating the pathogenesis of DFU, including oxidative stress, chronic inflammation, cell phenotype change, vasculopathy, and infection. This review also pointed out some of the shortcomings of hydrogels in present researches.

CONCLUSIONS

Hydrogels were classified into carrier hydrogels and self-functioning hydrogels in this review. Besides, the functions and components of existing hydrogels were clarified to provide assistance for future researches and clinical applications.

Concomitants of Diabetic Foot Ulcer - A Review

BACKGROUND

Diabetes mellitus leading to foot ulcer is a serious complication, and it is considered a global epidemic. Neuropathyand high blood glucose levels are the primary causes of foot ulcers. Fifteen percent of people with diabetes develop foot ulcers, and these foot disorders are the main cause of lower extremity amputation among such patients.

INTRODUCTION

Complications of diabetic foot, affecting the lower extremities are common and quite complex and life-threatening. This review focuses on the life-threatening factors associated with diabetic foot ulcers and also the diagnosing and preventive measures. Neuropathy assessment and the range of foot ulcers were accurately examined.

CONCLUSION

Novel therapies focusing on the vascularity of the lower limbs, infection control, and ischemic control are being developed to mainly treat nonhealing ulcers.

Effects of individually optimized rocker midsoles and self-adjusting insoles on plantar pressure in persons with diabetes mellitus and loss of protective sensation

INTRODUCTION

Rocker shoes and insoles reduce peak pressure (PP) in persons with diabetes (DM) and loss of protective sensation (LOPS). However, they are handmade, leading to inconsistent effectiveness. If foot structure changes over time, high PP-locations also change. To address this, individualized algorithm based 3D-printed rockers and self-adjusting pressure-reducing insoles are applied.

METHODS

PP across seven foot regions was analyzed in 21 persons with DM and LOPS. Regions with PP < 200 kPa were considered not at risk (RnoR); regions with PP ≥ 200 kPa at risk (RaR). The aim was to offload RaR, while remaining PP < 200 kPa in RnoR.

RESULTS

Individualized rockers and self-adjusting insoles combined successfully reduce PP < 200 kPa (on average 24 % - 48 %) in all feet with toes, central and lateral forefoot identified as RaR. Same intervention reduces PP in 68 % of the feet with medial forefoot identified as RaR. With the heel as RaR, no intervention reduces PP successfully in all feet.

CONCLUSIONS

Individualized 3D-printed rockers combined with self-adjusting insoles reduce PP (< 200 kPa) in toes, central and lateral forefoot, but not in heels. Alternative insoles with medial arch support, heel cup and compliant midsole materials might enhance success rate across entire foot.

STrain Analysis and Mapping of the Plantar Surface (STAMPS): A novel technique of plantar load analysis during gait

Diabetic foot ulceration is driven by peripheral neuropathy, resulting in abnormal foot biomechanics and elevated plantar load. Plantar load comprises normal pressure and tangential shear stress. Currently, there are no in-shoe devices measuring both components of plantar load. The STAMPS (STrain Analysis and Mapping of the Plantar Surface) system was developed to address this and utilises digital image correlation (DIC) to determine the strain sustained by a plastically deformable insole, providing an assessment of plantar load at the foot-surface interface during gait. STAMPS was developed as a multi-layered insole, comprising a deformable mid-layer, onto which a stochastic speckle pattern film is applied. A custom-built imaging platform is used to obtain high resolution pre- and post-walking images. Images are imported into commercially available DIC software (GOM Correlate, 2020) to obtain pointwise strain data. The strain and displacement data are exported and post-processed with custom analysis routines (MATLAB, Mathworks Inc.), to obtain the resultant global and regional peak strain (SMAG), antero-posterior strain (SAP) and medio-lateral strain (SML). To validate the core technique an experimental test process used a Universal Mechanical Tester (UMT) system (UMT TriboLab, Bruker) to apply controlled vertical and tangential load regimes to the proposed multi-layer insole. A pilot study was then conducted to assess the efficacy of using the STAMPS system to measure in-shoe plantar strain in three healthy participants. Each participant walked 10 steps on the STAMPS insole using a standardised shoe. They also walked 10 m in the same shoe using a plantar pressure measurement insole (Novel Pedar®) to record peak plantar pressure (PPP) as a gold-standard comparator. The results of the experimental validation tests show that with increased normal force, at a constant shear distance, SMAG increased in a linear fashion. Furthermore, they showed that with increased shear distance, at a constant force, SMAG increased. The results of the pilot study found participant 1 demonstrated greatest SMAG in the region toes 3-5 (15.31%). The highest mean SMAG for participant 2 was at the hallux (29.31%). Participant 3 exhibited highest strain in the regions of the first and second metatarsal heads (58.85% and 41.62% respectively). Increased PPP was strongly associated with increased SMAG with a Spearman's correlation coefficient 0.673 (p < 0.0001). This study has demonstrated the efficacy of a novel method to assess plantar load across the plantar surface of the foot. Experimental testing validated the sensitivity of the method to both normal pressure and tangential shear stress. This technique was successfully incorporated into the STAMPS insole to reliably measure and quantify the cumulative degree of strain sustained by a plastically deformable insole during a period of gait, which can be used to infer plantar loading patterns. Future work will explore how these measures relate to different pathologies, such as regions at risk of diabetic foot ulceration.

Digital Biomarkers of Gait and Balance in Diabetic Foot, Measurable by Wearable Inertial Measurement Units: A Mini Review

People with diabetic foot frequently exhibit gait and balance dysfunction. Recent advances in wearable inertial measurement units (IMUs) enable to assess some of the gait and balance dysfunction associated with diabetic foot (i.e., digital biomarkers of gait and balance). However, there is no review to inform digital biomarkers of gait and balance dysfunction related to diabetic foot, measurable by wearable IMUs (e.g., what gait and balance parameters can wearable IMUs collect? Are the measurements repeatable?). Accordingly, we conducted a web-based, mini review using PubMed. Our search was limited to human subjects and English-written papers published in peer-reviewed journals. We identified 20 papers in this mini review. We found preliminary evidence of digital biomarkers of gait and balance dysfunction in people with diabetic foot, such as slow gait speed, large gait variability, unstable gait initiation, and large body sway. However, due to heterogeneities in included papers in terms of study design, movement tasks, and small sample size, more studies are recommended to confirm this preliminary evidence. Additionally, based on our mini review, we recommend establishing appropriate strategies to successfully incorporate wearable-based assessment into clinical practice for diabetic foot care.

Factors Associated with the Local Increase of Skin Temperature, 'Hotspot,' of Callus in Diabetic Foot: A Cross-Sectional Study

BACKGROUND

Increased local skin temperature (hotspot) on a callus site as detected by thermography is a well-known precursor of diabetic foot ulcers. This study aimed to determine the factors associated with callus hotspots in order to predict the risk of callus hotspots and then provide information for specific interventions.

METHODS

In this cross-sectional study, 1,007 patients' data from a diabetic foot prevention clinic between April 2008 and March 2020 were used. Data regarding patients' characteristics, foot calluses, and callus hotspots were collected and analyzed. Callus and callus hotspot were confirmed from foot photos and thermographs, respectively. A callus hotspot was defined as a relative increase in temperature compared to the skin surrounding the callus on the thermograph. Plantar pressure was measured with a pressure distribution measurement system. A generalized linear mixed model was used to identify the factors associated with callus hotspots.

RESULTS

Among the 2,014 feet, 28.5% had calluses, and 18.5% of feet with calluses had callus hotspots. The factors associated with callus hotspots were number of calluses (Adjusted odds ratio (aOR): 1.540, P = .003), static forefoot peak plantar pressure (SFPPP) (aOR: 1.008, P = .001), and body mass index (aOR: 0.912, P = .029).

CONCLUSIONS

Patients with a higher SFPPP were more likely to have callus hotspots suggesting that SFPPP might contribute to callus inflammation. SFPPP has the potential to be a useful predictor of callus hotspots in people with diabetes and at the same time provide information for off-loading interventions to prevent callus hotspots.

Effects of a 12-Week Interventional Exercise Programme on Muscle Strength, Mobility and Fitness in Patients With Diabetic Foot in Remission: Results From BIONEDIAN Randomised Controlled Trial

OBJECTIVES

Diabetic foot syndrome (DFS) is a serious late diabetic complication characterised by limited joint mobility and other biomechanical and muscle abnormalities.

AIM

To evaluate the effect of an interventional exercise programme on anthropometric parameters, muscle strength, mobility and fitness in patients with diabetic foot in remission.

DATA SOURCES AND STUDY SELECTION

Thirty-eight patients with type 2 diabetes and DFS without active lesions (mean age 65 ± 6.9 years, BMI 32 ± 4.7 kg.m^-2, waist-hip ratio (WHR)1.02 ± 0.06) were enrolled in our randomised controlled trial. All subjects were randomised into two groups: an intervention group (I; n=19) and a control group (C; n=19). The 12-week exercise intervention focused on ankle and small-joint mobility in the foot, strengthening and stretching of the lower extremity muscles, and improvements in fitness. Changes (Δ=final minus initial results) in physical activity were assessed using the International Physical Activity Questionnaire (IPAQ), with joint mobility detected by goniometry, muscle strength by dynamometry, and fitness using the Senior Fitness Test (SFT).

DATA EXTRACTION

Due to reulceration, 15.8% of patients from group I (3/19) and 15.8% of patients from group C were excluded. Based on the IPAQ, group I was more active when it came to heavy (p=0.03) and moderate physical activity (p=0.06) after intervention compared to group C. Group I improved significantly in larger-joint flexibility (p=0.012) compared to controls. In group I, dynamometric parameters increased significantly in both lower limbs (left leg; p=0.013, right leg; p=0.043) compared to group C. We observed a positive trend in the improvement of fitness in group I compared to group C. We also confirmed positive correlations between heavy physical activity and selected parameters of flexibility (r=0.47; p=0.007), SFT (r=0.453; p=0.011) and dynamometry (r=0.58; p<0.0025). Anthropometric parameters, such as BMI and WHR, were not significantly influenced by the intervention programme.

CONCLUSION

Our 12-week interventional exercise programme proved relatively safe, resulting in improved body flexibility and increased muscle strength in DF patients in remission.

Reliability of ultrasound in evaluating the plantar skin and fat pad of the foot in the setting of diabetes

Ultrasound can be used to assess injury and structural changes to the soft-tissue structure of the foot. It may be useful to assess the feet of people with diabetes who are at increased risk of plantar soft-tissue pathological changes. The aim of this study was to determine if ultrasound measurements of plantar soft-tissue thickness and assessments of tissue acoustic characteristics are reliable in people with and without diabetes mellitus. A repeated measures design was used to determine intra-observer reliability for ultrasound measurements of plantar skin and fat pad thickness and intra- and inter-observer reliability of plantar skin and fat pad tissue characterisation assessments made at foot sites which are at risk of tissue injury in people with diabetes. Thickness measurements and tissue characterisation assessments were obtained at the heel and forefoot in both the unloaded and compressed states and included discrete layers of the plantar tissues: skin, microchamber, horizontal fibrous band, macrochamber and total soft-tissue depth. At each site, relative intra-observer reliability was achieved for the measurement of at least one plantar tissue layer. The total soft-tissue thickness measured in the unloaded state (ICC 0.925-0.976) demonstrated intra-observer reliability and is the most sensitive for detecting small change on repeated measures. Intra-observer agreement was demonstrated for tissue characteristic assessments of the skin at the heel (k = 0.70), fat pad at the lateral sesamoid region (k = 0.70) and both skin and fat pad at the second (k = 0.80, k = 0.70 respectively) and third metatarsal heads (k = 0.90, k = 0.79 respectively). However, acceptable inter-observer agreement was not demonstrated for any tissue characteristic assessment, therefore the use of multiple observers should be avoided when making these assessments.

Associations between changes in loading pattern, deformity, and internal stresses at the foot with hammer toe during walking; a finite element approach

Over the past decade, Finite Element (FE) modelling has been used as a method to understand the internal stresses within the diabetic foot. Foot deformities such as hammer toe have been associated with increased risk of foot ulcers in diabetic patients. Hence the aim of this study is to investigate the influence of hammer toe deformity on internal stresses during walking. A 3D finite element model of the human foot was constructed based on capturing Magnetic Resonance Imaging (MRI) of a diabetic neuropathic volunteer exhibiting hammer toe. 3D gait measurements and a multi-body musculoskeletal model for the same participant were used to define muscle forces. FE simulations were run at five different instances during the stance phase of gait. Peak plantar pressure and pressure distribution results calculated from the model showed a good agreement with the experimental measurement having less than 11% errors. Maximum von Mises internal stresses in the forefoot hard tissue were observed at the 3^rd and 5^th metatarsals and 4^th proximal phalanx. Moreover, presence of hammer toe deformity was found to shift the location of maximum internal stresses on the soft tissue to the forefoot by changing the location of centre of pressure with internal stress 1.64 times greater than plantar pressure. Hammer toe deformity also showed to reduce the involvement of the first phalanx in internal/external load-bearing during walking. The findings of this study support the association between changes in loading pattern, deformity, and internal stresses in the soft tissue that lead to foot ulceration.

Ankle and foot mechanics in individuals with chronic ankle instability during shod walking and barefoot walking: A cross-sectional study

PURPOSE

This study evaluated the angular kinematic and moment of the ankle and foot during shod walking and barefoot walking in individuals with unilateral chronic ankle instability (CAI).

METHODS

Recreational soccer players with unilateral CAI were recruited for this cross sectional study conducted between January and August 2019. A total of 40 participants were screened for eligibility but only 31 met the inclusion criteria based on the methods of Delahunt et al and Gribble et al. Except for 3 participants not attending the evaluation session, 28 participants were finally included. A three dimensional motion analysis system made up of ProReflex motion capture unit and an AMTIb Kistler force plate, embedded in the middle of nine meter walkway, were used to assess the ankle and foot angles and moment during shod walking and barefoot walking conditions. A Statistical Package for Social Sciences (version 20.0) was used to analyze data.

RESULTS

During shod walking, the ankle joint plantar-flexion range of motion (ROM) at 10% of the gait cycle (GC) and dorsiflexion ROM at 30% of the GC were significantly higher than those during barefoot walking for both feet (p = 0.001, 0.001, 0.027, and 0.036 respectively). The inversion ROM during shod walking was significantly higher than that during barefoot walking for both feet at 10% and 30% of the GC (p = 0.001. 0.001, 0.001, and 0.042 respectively). At 10% of the GC, the eversion moment was significantly higher between barefoot and shod walking for both feet (both p = 0.001). At 30% of the GC, there was no significant difference between shod and barefoot walking plantar-flexion moment of both feet (p = 0.975 and 0.763 respectively), and the eversion moment of both feet (p = 0.116 and 0.101 respectively).

CONCLUSION

At the early stance, shod walking increases the ankle plantar-flexion and foot inversion ROM, and decreases the eversion moment for both feet in subjects with unilateral CAI. Therefore, the foot wearing condition should be considered during evaluation of ankle and foot kinematics and kinetics.

Facile Fabrication of Flexible Pressure Sensor with Programmable Lattice Structure

Flexible pressure sensors have attracted intense attention because of their widespread applications in electronic skin, human-machine interfaces, and healthcare monitoring. Conductive porous structures are always utilized as active layers to improve the sensor sensitivities. However, flexible pressure sensors derived from traditional foaming techniques have limited structure designability. Besides, random pore distribution causes difference in structure and signal repeatability between different samples even in one batch, therefore limiting the batch production capabilities. Herein, we introduce a structure designable lattice structure pressure sensor (LPS) produced by bottom-up digital light processing (DLP) 3D printing technique, which is capable of efficiently producing 55 high fidelity lattice structure models in 30 min. The LPS shows high sensitivity (1.02 kPa^-1) with superior linearity over a wide pressure range (0.7 Pa to 160 kPa). By adjusting the design parameters such as lattice type and layer thickness, the electrical sensitivities and mechanical properties of LPS can be accurately controlled. In addition, the LPS endures up to 60000 compression cycles (at 10 kPa) without any obvious electrical signal degradation. This benefits from the firm carbon nanotubes (CNTs) coating derived from high-energy ultrasonic probe and the subsequent thermal curing process of UV-heat dual-curing photocurable resin. For practical applications, the LPS is used for real time pulse monitoring, voice recognition and Morse code communication. Furthermore, the LPS is also integrated to make a flexible 4 × 4 sensor arrays for detecting spatial pressure distribution and a flexible insole for foot pressure monitoring.

The Design and Simulation of a 16-Sensors Plantar Pressure Insole Layout for Different Applications: From Sports to Clinics, a Pilot Study

The quantification of plantar pressure distribution is widely done in the diagnosis of lower limbs deformities, gait analysis, footwear design, and sport applications. To date, a number of pressure insole layouts have been proposed, with different configurations according to their applications. The goal of this study is to assess the validity of a 16-sensors (1.5 × 1.5 cm) pressure insole to detect plantar pressure distribution during different tasks in the clinic and sport domains. The data of 39 healthy adults, acquired with a Pedar-X® system (Novel GmbH, Munich, Germany) during walking, weight lifting, and drop landing, were used to simulate the insole. The sensors were distributed by considering the location of the peak pressure on all trials: 4 on the hindfoot, 3 on the midfoot, and 9 on the forefoot. The following variables were computed with both systems and compared by estimating the Root Mean Square Error (RMSE): Peak/Mean Pressure, Ground Reaction Force (GRF), Center of Pressure (COP), the distance between COP and the origin, the Contact Area. The lowest (0.61%) and highest (82.4%) RMSE values were detected during gait on the medial-lateral COP and the GRF, respectively. This approach could be used for testing different layouts on various applications prior to production.

Does the Application of a Semiocclusive Dressing Alter the Microflora of Healthy Intact Skin on the Foot?

BACKGROUND

The skin on human feet presents unique environments for the proliferation of potentially pathogenic commensals. This study examined microflora changes on healthy intact skin under a semiocclusive dressing on the medial longitudinal arch of the foot to determine changes in growth, distribution, and frequency of microflora under the dressing.

METHODS

Nine human participants wore a low-adherent, absorbent, semiocclusive dressing on the medial longitudinal arch of the left foot for 2 weeks. An identical location on the right foot was swabbed and used as a control. Each foot was swabbed at baseline, week 1, and week 2. The swabs were cultured for 48 hours. Visual identification, Gram staining, DNase test agar, and a latex slide agglutination test were used to identify genera and species.

RESULTS

Microflora growth was categorized as scant (0-10 colony-forming units [CFU]), light (11-50 CFU), moderate (51-100 CFU), or heavy (>100 CFU). Scant and light growth decreased and moderate and heavy growth increased under the dressing compared with the control. Seven different genera of bacteria were identified. Coagulase-negative Staphylococcus spp appeared most frequently, followed by Corynebacterium spp.

CONCLUSIONS

Changes in microflora distribution, frequency, and growth were found under the dressing, supporting historical studies. Microflora changes were identified as an increase in bioburden and reduction in diversity. The application of similar methods, using more sophisticated identification and analysis techniques and a variety of dressings, could lead to a better understanding of bacterial and fungal growth under dressings, informing better dressing selection to assist the healing process of wounds and prevent infection.

A smart wearable device for monitoring and self-management of diabetic foot: A proof of concept study

BACKGROUND AND OBJECTIVE

Diabetic foot is one of the important complications of diabetes, which is occurred due to the destructive parameters in different anatomical sites of feet. Management and monitoring of these parameters are very important to decrease or prevent foot ulcers. We aimed to develop a smart wearable device to monitor these parameters to prevent diabetic foot.

METHODS

Following literature review and expert panel discussions, we considered pressure, temperature and humidity to develop the system. During these sessions, we also developed the system architecture and determined the required technologies. We also developed a mobile application. Finally, all sensors were evaluated for accurate monitoring of pressure, temperature and humidity. A standard protocol was used to evaluate each of these sensors. To this end, five people (four with diabetes and one healthy person) participated. They did a series of movements including walking, sitting, and standing. We considered the pressure measured by Pedar system as the gold standard. Furthermore, we changed the environment temperature and humidity during several experiments and considered the environment temperature and humidity as gold standard. We compared the measured values by sensors with these gold standards.

RESULTS

The evaluation indicated the accurate performance of pressure, humidity and temperature sensors. Sensitivity, specificity, accuracy, positive predictive value, and negative predictive value of the system to provide alarms based on the pressure measured using Pedar were 100, 50, 92.5, 91.8, and 100 %, respectively. The performance of temperature sensors in smart shoes was confirmed by slight differences compared to thermometers. Relatively equal values of humidity measured by two sensors on the left and right feet and the increased difference with the environment humidity showed the exact humidity measured using these sensors.

CONCLUSION

This smart shoes monitors pressure, humidity, and temperature of patients' feet and sends this data to their smart phone by the Bluetooth module. Furthermore, it controls these parameters; as each of these parameters exceeds the defined threshold, alerts are given to patients for self-management.

The Role of Foot-Loading Factors and Their Associations with Ulcer Development and Ulcer Healing in People with Diabetes: A Systematic Review

We aimed to comprehensively and systematically review studies associating key foot-loading factors (i.e., plantar pressure, weight-bearing activity, adherence or a combination thereof) with ulcer development and ulcer healing in people with diabetes. A systematic literature search was performed in PubMed and EMBASE. We included studies if barefoot or in-shoe plantar pressure, weight-bearing activity or footwear or device adherence was measured and associated with either ulcer development or ulcer healing in people with diabetes. Out of 1954 records, 36 studies were included and qualitatively analyzed. We found low to moderate quality evidence that lower barefoot plantar pressure and higher footwear and device adherence associate with lower risk of ulcer development and shorter healing times. For the other foot-loading factors, we found low quality evidence with limited or contradictory results. For combined measures of foot-loading factors, we found low quality evidence suggesting that lower cumulative plantar tissue stress is associated with lower risk of ulcer development and higher ulcer healing incidence. We conclude that evidence for barefoot plantar pressure and adherence in association with ulcer outcome is present, but is limited for the other foot-loading factors. More comprehensive investigation in particularly the combination of foot-loading factors may improve the evidence and targeting preventative treatment.

The Association of Diabetes With Knee Pain Locations, Pain While Walking, and Walking Speed: Data From the Osteoarthritis Initiative

OBJECTIVE

Osteoarthritis (OA) and diabetes mellitus (DM) often coexist and can result in negative outcomes. DM can affect pain and walking speed in people with knee OA; however, the impact of DM on OA is understudied. The purpose of this study was to investigate the association between diabetes and knee pain locations, pain severity while walking, and walking speed in people with knee OA.

METHODS

A cross-sectional analysis was used. Data from 1790 individuals from the Osteoarthritis Initiative (mean [SD] age = 69 [8.7] years) with knee pain were included and grouped into knee OA and diabetes (n = 236) or knee OA only (n = 1554). Knee pain locations were categorized as no pain, localized pain, regional pain, or diffuse pain. Knee pain during a 20-m walk test was categorized as no pain, mild, moderate, or severe knee pain. Walking speed was measured using the 20-m walk test. Multinomial and linear regression analyses were performed.

RESULTS

Diabetes was associated with regional knee pain (odds ratio [OR] = 1.77; 95% CI = 1.01-3.11). Diabetes was associated only with moderate (OR = 1.78; 95% CI = 1.02-3.10) or severe (OR = 2.52; 95% CI = 1.01-6.28) pain while walking. Diabetes was associated with decreased walking speed (B = -0.064; 95% CI = -0.09 to -0.03).

CONCLUSIONS

Diabetes was associated with regional knee pain but not with localized or diffuse knee pain and was associated with moderate to severe knee pain while walking and slower walking speed in people with knee OA.

IMPACT

Clinicians can use a knee pain map for examining knee pain locations for people with diabetes and knee OA. Knee pain during walking and walking speed should be screened for people with knee OA and diabetes because of the influence of diabetes on these parameters in this population.

LAY SUMMARY

Diabetes might be associated with specific knee pain locations, pain during activities such as walking, and reduced walking speed in people with knee OA.

Clustering classification of diabetic walking abnormalities: a new approach taking into account intralimb coordination patterns

BACKGROUND

It is well recognized that diabetes and peripheral neuropathy have a detrimental effect on gait. However, there are large variations in the results of studies addressing this aspect due to the heterogeneity of diabetic population in relation to presence and severity of diabetes complications. The aim of this study is to adopt an unsupervised classification technique to better elucidate the gait changes throughout the entire spectrum of diabetes and neuropathy.

METHODS

Sixty subjects were assessed and classified into four groups using a fuzzy logic model: 13 controls (55 ± 7years), 18 diabetics subjects without neuropathy (59 ± 6 years, 11 ± 7 diabetes years), 7 with mild neuropathy (56 ± 4years, 19 ± 7 diabetes years), and 22 with moderate to severe neuropathy (57 ± 5 years, 14 ± 8 diabetes years). Data were gathered by six infrared cameras at 100 Hz regarding lower limb joint kinematics (angles and angular velocities) and the relative phase for the hip-ankle, hip-knee, and knee-ankle were calculated. The K-means clustering algorithm was adopted to classify subjects considering the whole kinematics time series. A one-way ANOVA test was used to compare both clinical and kinematics parameters across clusters.

RESULTS

Only the classification based on the intralimb coordination variables succeeded in defining 5 well separated clusters with the following clinical characteristics: controls were grouped mainly in Cluster 2, diabetics in Cluster 4, and neuropathic subjects in Cluster 5 (which included various degrees of severity). Hip-ankle coordination in Clusters 4 and 5 were significantly different (p < 0.05) with respect to Cluster 2, mainly in the stance phase. During the swing phase, differences were observed in the ankle-knee coordination (p < 0.05) across clusters.

CONCLUSION

Classification based on intralimb coordination patterns succeeded in efficiently categorize gait alterations in diabetic subjects. It can be speculated that variables extracted from sagittal plane kinematics might be adopted as a support to clinical decision making in diabetes.

Does the application of Opsite⋄ Flexigrid⋄ occlude the oxygen saturation readings in healthy individuals using the moorVMS-OXY machine?

Background

A proportion of people who have been diagnosed with peripheral arterial disease and diabetes mellitus will be susceptible to chronic wounds. Oxygen is vital for wound healing, so oxygen measurements should to be taken as predictive values for wound healing in patients. When measuring oxygen at the wound bed, there is potentially a risk of cross-infection if no protective barrier is used; and skin stripping if an adhesive barrier is used on the wound bed. This cross sectional within subject repeated measures pilot study, aims to determine if the application of opsite film, as an infection control measure, in one or two layers, impacts on tissue oxygenation readings obtained when using the MoorVMS-OXY.

Methods

Mean oxygen saturation percentages were measured from 29 limbs of 18 healthy participants. Oxygen saturation was measured for 20 s and analysed at the first metatarsophalangeal joint using no film, one and two layers using the MoorVMS-OXY. A one-way repeated ANOVA with a Bonferroni post hoc test was performed to test for statistically significant differences between the values of the three parameters and multiple pairwise comparisons was completed.

Results

Amongst the three layers, there was a statistically significant difference in oxygen saturation between the two layers of Opsite Flexigrid and none; and also between the two layers of Flexigrid and single layer (p < 0.05). It was also established that there was no statistically significant difference between the single layer of Opsite Flexigrid and no Flexigrid layer (p > 0.05).

Conclusions

The results imply that one layer of Opsite Flexigrid is a suitable protective barrier to use when establishing capillary bed oxygen perfusion with the MoorVMS-OXY. However, the application of two Opsite Flexigrid layers, to prevent skin stripping, decreases the recorded values of oxygen saturation percentages significantly, therefore providing inaccurate results. Indicating that a double layer cannot be used over ulceration sites if measuring oxygen levels at the wound bed.

The role of foot pressure measurement in the prediction and prevention of diabetic foot ulceration-A comprehensive review

The predominant risk factor of diabetic foot ulcers (DFU), peripheral neuropathy, results in loss of protective sensation and is associated with abnormally high plantar pressures. DFU prevention strategies strive to reduce these high plantar pressures. Nevertheless, several constraints should be acknowledged regarding the research supporting the link between plantar pressure and DFUs, which may explain the low prediction ability reported in prospective studies. The majority of studies assess vertical, rather than shear, barefoot plantar pressure in laboratory-based environments, rather than during daily activity. Few studies investigated previous DFU location-specific pressure. Previous studies focus predominantly on walking, although studies monitoring activity suggest that more time is spent on other weight-bearing activities, where a lower "peak" plantar pressure might be applied over a longer duration. Although further research is needed, this may indicate that an expression of cumulative pressure applied over time could be a more relevant parameter than peak pressure. Studies indicated that providing pressure feedback might reduce plantar pressures, with an emerging potential use of smart technology, however, further research is required. Further pressure analyses, across all weight-bearing activities, referring to location-specific pressures are required to improve our understanding of pressures resulting in DFUs and improve effectiveness of interventions.

Monitoring of external predisposing factors for Diabetic Foot: A literature review and physicians' perspectives

Background: Diabetic foot is one of the most important complications of diabetes caused by the existence of some destructive factors in different anatomical locations of feet. Management and monitoring of these factors are very important to decrease or avoid ulcerating lesions of the foot. The purpose of this study is to identify and introduce the predisposing factors and anatomical locations associated with these destructive factors. Methods: First, we conducted a comprehensive review of different databases to identify the factors and associated anatomical locations from the previous studies. Then, we designed a questionnaire and invited physicians and specialists to express their perspectives on these factors and locations. The data were analyzed using SPSS version 23. Frequency, percentage, mean and standard deviation of these variables were calculated. Results: Based on the literature review, four factors, including pressure, moisture and sweat, temperature, and acceleration were identified as factors destructive to the tissues of the diabetic foot and worsen ulcers. The view of specialists approved the results of the literature review. Besides, there was an insignificant difference between the results of the literature review and the specialists' view in terms of anatomical locations that need to be continuously monitored. Conclusion: Monitoring the pressure in heel, first metatarsal, and first metatarsal head; moisture and sweat under the fingers, hallux and heels as well as the temperature at the first metatarsal, first metatarsal head, and the third metatarsal head are important in preventing ulceration, destructing the foot tissue, and accelerating the treatment process.

Cross-cultural Adaptation and Validation of the French Version of the Diabetic Foot Self-care Questionnaire of the University of Malaga

BACKGROUND

Diabetic foot care management is directed at patients with a history of complications, especially those with rising levels of hemoglobin A_1c, and those who have had diabetes for several years. The aim of this study was to cross-culturally adapt a French-language version of the Diabetic Foot Self-care Questionnaire of the University of Malaga (DFSQ-UMA) for use in France.

METHODS

Cross-cultural adaptation was performed according to relevant international guidelines (International Society for Pharmacoeconomics and Outcomes Research), and the factor structure was determined. Internal consistency was measured using the Cronbach α. Item-total and inter-item correlations were assessed.

RESULTS

The French data set comprised 146 patients. The mean ± SD patient age was 62.60 ± 15.47 years. There were 47 women and 99 men. The structure matrix (with three factors) was tested by confirmatory factor analysis. The 16-item questionnaire had a Cronbach α of 0.92. The mean value for inter-item correlations was 0.48 (range, 0.17-0.86). The rotated solution revealed a three-factor structure that accounted for 48.10% of the variance observed. A significant inverse correlation was observed between questionnaire scores and hemoglobin A_1c levels (r = -0.17; P < .01).

CONCLUSIONS

This study validates the French-language version of the DFSQ-UMA, which can be used as a self-reported outcome measure for French-speaking patients in France.

The effect of exercises and insoles on the feet in leprosy patients

ABSTRACT The purpose of this study is to analyze the effects of using customized insoles and leg and foot exercises on the feet of patients with neuropathy caused by leprosy. Thirty volunteers diagnosed with leprosy were assigned to one of three groups: (1) Exercise group (n=10): performed exercises for the intrinsic muscles of the foot; (2) Insole group (n=10): used insoles to correct foot positioning; (3) Insole and Exercise group (n=10): used insoles and performed an exercise routine. The results of the treatments were analyzed with photogrammetry using the Alcimagem® and AutoCAD® programs. Left hindfoot posture changed after treatment in the Exercise and Insole groups (hindfoot, pre versus post <0.001). We also found that combining exercise and insoles did not alter the alignment of the feet during the study’s evaluation period (customized insoles and exercises, pre versus post <0.05), which suggests that follow-up for more than four months may be needed. The left hindfoot’s alignment can be changed with supervised exercises and the use of insoles.

Healing ulcers and preventing their recurrences in the diabetic foot

Fifteen percent of people with diabetes develop an ulcer in the course of their lifetime. Eighty-five percent of the major amputations in diabetes mellitus are preceded by an ulcer. Management of ulcers and preventing their recurrence is important for the quality of life of the individual and reducing the cost of care of treatment. The main causative factors of ulceration are neuropathy, vasculopathy and limited joint mobility. Altered bio-mechanics due to the deformities secondary to neuropathy and limited joint mobility leads to focal points of increased pressure, which compromises circulation leading to ulcers. Ulcer management must not only address the healing of ulcers but also should correct the altered bio-mechanics to reduce the focal pressure points and prevent recurrence. An analysis of 700 patients presenting with foot problems to the Diabetic Clinic of Ganga Hospital led to the stratification of these patients into four classes of incremental severity. Class 1 – the foot at risk, Class 2 – superficial ulcers without infection, Class 3 – the crippled foot and Class 4 – the critical foot. Almost 77.5% presented in either Class 3 or 4 with complicated foot ulcers requiring major reconstruction or amputation. Class 1 foot can be managed conservatively with foot care and appropriate foot wear. Class 2 in addition to measures for ulcer healing would need surgery to correct the altered bio-mechanics to prevent the recurrence. The procedures called surgical offloading would depend on the site of the ulcer and would need an in-depth clinical study of the foot. Class 3 would need major reconstructive procedures and Class 4 would need amputation since it may be life-threatening. As clinicians, our main efforts must be focused towards identifying patients in Class 1 and offer advice on foot care and Class 2 where appropriate surgical offloading procedure would help preserve the foot.

Early Foot Structural Changes After Lateral Column Exostectomy in Patients With Charcot Foot

Although exostectomy for chronic midfoot plantar ulcers in Charcot foot is apparently effective, with healing rates of nearly 75%, a subset of patients develop recurrent ulceration and show an unstable foot position, especially after undergoing exostectomy confined to the lateral column. The reasons for this failure have not been investigated. The main objective of this study was to evaluate the early changes in radiographic alignment after an exostectomy in patients with Charcot neuropathic osteoarthropathy (rocker bottom) and plantar ulcer located in the lateral column. The present study evaluated retrospectively changes in radiographic alignment after an exostectomy in 12 Charcot feet (rocker bottom) with plantar ulcer located in the lateral column. Indication for plantar exostectomy was the treatment of ulcer affected by osteomyelitis. We evaluated the early changes in the alignment of the foot on weight-bearing lateral radiographs 6 months after exostectomy. Paired sample Wilcoxon test was used to calculate the differences between preoperative and postoperative measurements. Furthermore, the relationship between revision surgery and early changes in radiographic angular measurements was determined by using the Mann-Whitney U test. After exostectomy, the inclination of the calcaneal bone decreased ( P = .003; r = 0.849) and declination of talus bone increased ( P = .041; r = 0.589). The change in calcaneal inclination was associated with revision surgery ( P = .042; r = 0.586). The present case series demonstrates that exostectomy procedure for the lateral column in patients with Charcot foot results in radiological changes in the hindfoot over the sagittal plane. The inversion of the calcaneal pitch angle suggests the possibility of further adverse events and the need for revision surgery.

A convolutional neural network Cascade for plantar pressure images registration

BACKGROUND

Plantar pressure image (PPI) recorded in high spatial and temporal resolution is very useful in clinical gait analysis. For functional analysis of PPI, image registration is often performed to maximally correlate source image with a template image. Previous methods estimate the registration parameters by iteratively optimizing different objective functions. These methods are often computational expensive to achieve satisfactory registration accuracy.

RESEARCH QUESTION

Can we develop a single PPI registration technique that performs more rapidly than previous methods, and that also maintains adequate PPI correspondence as defined by various (dis)similarity metrics?

METHODS

A cascaded convolutional neural network (CNN) was proposed for the registration of PPIs. Our model was trained to learn a regression from the difference between the template and misaligned images to the registration parameters. The registration performance was evaluated by three different metrics, i.e. the mean squared error (MSE), the exclusive or (XOR), and the mutual information (MI). For comparison, four previous methods were also implemented. These included the principal axes (PA) method, the center of pressure trajectory (COP) method, the MSE method, and the XOR method.

RESULTS

Experimental results on a dataset with 71 PPI template-source pairs showed that the proposed CNN-based method could obtain comparable registration accuracy to the MSE and XOR method. With regards to the registration speed, registration durations (mean ± sd in seconds) per image pair were: MSE (30.584 ± 2.171), XOR (24.245 ± 1.596), PA (0.016 ± 0.003), COP (25.614 ± 0.341), and the proposed model (0.054 ± 0.007).

SIGNIFICANCE

Our findings indicate that the proposed registration approach can achieve high accuracy but less computational time. Thus, it is more practical to utilize our pre-trained CNN-based model to develop near-real time applications for plantar pressure images registration.

Distribution of the Highest Plantar Pressure Regions in Patients with Diabetes and Its Association with Peripheral Neuropathy, Gender, Age, and BMI: One Centre Study

The abnormal plantar pressure distribution and value play a key role in the formation of plantar calluses and diabetic foot ulcer. The prevalence of the highest pressure different distribution and its association with various factors among patients with diabetes is not well known. The study purpose was to evaluate the prevalence of different regions for the highest pressure on the sole and its association with selected factors among patients with diabetes. Medical records of nonulcer patients were retrospectively analysed. The relationship between pressure patterns on the sole obtained during a pedobarographic test as a semiquantitative assessment with colourful print analysis and neuropathy, gender, age, and BMI was searched. The most common location of the highest pressure was the central part of the forefoot. No association was found between the different highest pressure regions and age, sensory neuropathy, calluses, and foot deformities. The highest pressure on the lateral part of the foot and midfoot was observed more often in females and in patients with a BMI ≥ 35. The prevalence of the highest pressure on the forefoot was more common in patients with a BMI < 35. Conclusions. The most frequent regions of the highest pressure on the sole in patients with diabetes were the central part of the forefoot (2-3 metatarsal heads) with no simple relationship to the assessed variables other than BMI < 35. Female gender and higher BMI seem to be responsible for shifting the place of the highest pressure to other places of the foot.

Effects of nanoparticles of hydroxy-aluminum phthalocyanine on markers of liver injury and glucose metabolism in diabetic mice

Photodynamic therapy, by reducing pain and inflammation and promoting the proliferation of healthy cells, can be used to treat recurrent lesions, such as diabetic foot ulcers. Studies using the photosensitizer phthalocyanine, together with the nanostructured copolymeric matrix of Pluronic® and Carbopol® for the treatment of diabetic foot ulcers and leishmaniosis lesions, are showing promising outcomes. Despite their topical or subcutaneous administration, these molecules are absorbed and their systemic effects are unknown. Therefore, we investigated the effect of the subcutaneous administration of the hydroxy-aluminum phthalocyanine hydrogel without illumination on systemic parameters, markers of liver injury, and liver energy metabolism in type 1 diabetic Swiss mice. Both the hydrogel and the different doses of phthalocyanine changed the levels of injury markers and the liver glucose release, sometimes aggravating the alterations caused by the diabetic condition itself. However, the dose of 2.23 µg/mL caused less marked plasmatic and metabolic changes and did not change glucose tolerance or insulin sensitivity of the diabetic mice. These results are indicative that the use of hydroxy-aluminum phthalocyanine hydrogel for the treatment of cutaneous ulcers in diabetic patients is systemically safe.

Novel insole design for diabetic foot ulcer management

Around the world, over 400 million people suffer from diabetes. In a chronic diabetic condition, the skin underneath the foot often becomes extremely soft and brittle, resulting in the development of foot ulcers. In literature, a plethora of footwear designs have been developed to reduce the induced stresses on a diabetic foot and to consequently prevent the incidences of foot ulcers. However, to date, no insole design exists which can handle post-ulcer diabetic foot conditions without hindering the mobility of the patients. In the current work, a novel custom insole design with arch support and ulcer isolations was tested for effective stress reduction in a diabetic foot with ulcers using finite element modeling. A full-scale model of the foot was developed with ulcers of different geometries and sizes at the heel and metatarsal regions of the foot. The stresses at the ulcer locations were quantified for standing and walking with and without the novel custom insole model. The effect of material properties of the insole on the ulcer stress reduction was quantified extensively. Also, the effectivity of a novel synthetic skin material as the insole material was tested for stress offloading at the ulcers and the rest of the foot. From the analyses, peak stress reductions were observed at the ulcers up to 91.5% due to the ulcer isolation in the novel custom insole design and the skin-like material. Specifically, the ulcer isolation feature in the insole was found to be approximately 25% more effective in peak stress reduction for commonly occurring ulcers with irregular geometry, over the tested regular circular ulcer geometry. Also, a threshold material stiffness was found for the custom insole, below which the peak stresses at the ulcers did not decrease any further. Based on this information, a working prototype of the custom insole was developed with custom ulcer isolations, which will be subjected to further testing. The results of this study would inform better custom insole designing and material selection for post-ulcer diabetic conditions, with effective stress reduction at the ulcers, and the possibilities of preventing further ulceration.

Quadriceps muscle architecture ultrasonography of individuals with type 2 diabetes: Reliability and applicability

Muscle architecture parameters performed using ultrasound serve as an aid to monitor muscle changes derived from diseases, however there are no studies that determine the reliability and applicability of this evaluation in individuals with type 2 diabetes (DM2). Three raters captured three images of measurements of thickness of the rectus femoris (RF), vastus intermedius and anterior quadriceps, RF muscle cross-sectional area, RF pennation angle in 17 individuals with DM2 above 50 and sedentary. Intra and inter-raters analysis showed reliability from high to very high for the three raters (ICC> 0.87), except for the RF pennation angle with moderate to low intra-raters (ICC = 0.58, 0.48, 0.51), and high inter-rater reliability (ICC = 0.70). Ultrasound measurements of quadriceps muscles showed high to very high intra and inter-raters reliability, thus allowing its use to monitor muscle changes provoked by diabetes or interventions in individuals with DM2.

Risk factors for diabetic foot ulcer recurrence: A prospective 2-year follow-up study in Egypt

OBJECTIVES

To determine the frequency of diabetic foot ulcer recurrence and its potential risk factors.

METHODS

This study included 93 patients with type 2 diabetes and followed for 2 years after primary healed foot ulceration. Demographic, diabetes related, comorbid and ulcer related variables were investigated as risk factors. Multiple logistic regression analysis was used to identify independent risk factors.

RESULTS

61.3% of patients had recurrent ulcers particularly in the forefoot (33.3%) and big toe (24.6%). Peripheral neuropathy, peripheral arterial disease or both were reported in 69%, 12% and 19% of feet with recurrent ulcers respectively. In multivariate analysis, the significant independent potential risk factors for recurrence of foot ulcers were smoking (P=0.040), poor glycemic control [HbA1c cutoff of 10%] (P=0.010), peripheral neuropathy with lost ankle reflex (P=0.0001), peripheral arterial disease (P=0.0001) and previous ulcer location (P=0.050).

CONCLUSION

The frequency rate of recurrent diabetic foot ulceration in patients with type 2 diabetes is high particularly in the first year despite regular follow-up and patient education.

Duration of Type 2 Diabetes is a Predictor of Elevated Plantar Foot Pressure

AIMS

Elevated plantar pressure is considered a significant risk factor for ulceration in diabetes mellitus. The aim of this study was to determine whether duration of diabetes could affect plantar pressure in patients with no known significant comorbidity or foot pathology.

METHODS

Participants with type 2 diabetes, but without known confounding factors that could alter peak pressure, were matched for age, weight, and gender and categorized into 3 groups of diabetes duration: group 1 (1-5 yr), group 2 (6-10 yr), and group 3 (11-15 yr). Plantar pressures were recorded utilizing a two-step protocol at a self-selected speed.

RESULTS

One-way analysis of variance (ANOVA) revealed significant differences in mean peak plantar pressures between the three groups under the 2^nd - 4^th metatarsophalangeal joint (MPJ) region of interest (ROI) (p = 0.012 and p = 0.022, respectively) and left heel (p = 0.049). Also, a significant difference in mean pressure-time integral under the left 2^nd - 4^th MPJ ROI (p = 0.021) and right heel (p = 0.048) was observed. Regression analysis confirmed that mean peak plantar pressures in the first group (but not in the second group) were significantly lower than in the third group (p = 0.005).

CONCLUSIONS

As the duration of diabetes increased, peak plantar pressure increased significantly under the 2^nd - 4^th MPJ ROIs. These findings suggest that clinicians should make more use of pressure mapping technology as part of their clinical management plan in patients with diabetes >10 yr, even if they have no complications or deformities, to preserve functional limbs in this high-risk population.

Validation of plantar pressure simulations using finite and discrete element modelling in healthy and diabetic subjects

Plantar pressure simulation driven by integrated 3D motion capture data, using both a finite element and a discrete element model, is compared for ten healthy and ten diabetic neuropathic subjects. The simulated peak pressure deviated on average between 16.7 and 34.2% from the measured peak pressure. The error in the position of the peak pressure was on average smaller than 4.2 cm. No method was more accurate than the other although statistical differences were found between them. Both techniques are thus complementary and useful tools to better understand the alteration of diabetic foot biomechanics during gait.

Strategies towards rapid generation of forefoot model incorporating realistic geometry of metatarsals encapsulated into lumped soft tissues for personalized finite element analysis

Use of finite element (FE) foot model as a clinical diagnostics tool is likely to improve the specificity of foot injury predictions in the diabetic population. Here we proposed a novel workflow for rapid construction of foot FE model incorporating realistic geometry of metatarsals encapsulated into lumped forefoot's soft tissues. Custom algorithms were implemented to perform unsupervised segmentation and mesh generation to directly convert CT data into a usable FE model. The automatically generated model provided higher efficiency and comparable numerical accuracy when compared to the model constructed using a traditional solid-based mesh process. The entire procedure uses MATLAB as the main platform, and makes the present approach attractive for creating personalized foot models to be used in clinical studies.

Association between ankle equinus and plantar pressures in people with diabetes. A systematic review and meta-analysis

BACKGROUND

Diabetes is one of the most common chronic diseases in the world and is associated with a life-time risk of foot ulcer of 12-25%. Diabetes related restriction in ankle joint range of dorsiflexion is proposed to contribute to elevated plantar pressures implicated in the development of foot ulcers.

METHODS

A systematic search of EBSCO Megafile Premier (containing MEDLINE, CINAHL, SPORTSdiscus and Academic Search Complete) and The Cochrane Library was conducted to 23rd November 2016. Two authors independently reviewed and selected relevant studies. Meta-analysis of study data were conducted where possible.

FINDINGS

Fifteen studies met the inclusion criteria. Three studies were eligible to be included in the meta-analysis which found that equinus has a significant, but small, effect on increased plantar pressures (ES=0.26, CI 95% 0.11 to 0.41, p=0.001). Of the remaining studies, eight found evidence of an association between limited ankle dorsiflexion and increased plantar pressures while four studies found no relationship.

INTERPRETATION

Limited ankle joint dorsiflexion may be an important factor in elevating plantar pressures, independent of neuropathy. Limited ankle dorsiflexion and increased plantar pressures were found in all the studies where the sample population had a history of neuropathic foot ulceration. In contrast, the same association was not found in those studies where the population had neuropathy and no history of foot ulcer. Routine screening for limited ankle dorsiflexion range of motion in the diabetic population would allow for early provision of conservative treatment options to reduce plantar pressures and lessen ulcer risk.

Weight-Bearing Exercise and Foot Health in Native Americans

Diabetes contributes to sensory peripheral neuropathy, which has been linked to lower limb abnormalities that raise the risk for foot ulcers and amputations. Because amputations are a reason for pain and hospitalization in those with diabetes, it is of critical importance to gain insight about prevention of ulcer development in this population. Although the American Diabetes Association (ADA) now recommends that individuals with neuropathy can engage in moderate-intensity weight-bearing activity (WBA), they must wear appropriate footwear and inspect their feet daily. The physical forces and inflammatory processes from WBA may contribute to plantar characteristics that lead to ulcers. The purpose of this study was to compare neuropathic status and foot characteristics in Native Americans according to WBA classification. The t tests for unequal sample sizes found that exercisers had more difficulty sensing baseline temperature than nonexercisers, except at the right foot (all p values < .05). By dividing groups into no/low risk and high risk for ulcer, a majority showed no/low risk according to touch and vibration sense. Exercisers demonstrated higher surface skin temperature gradients at the first metatarsal head, a plantar site where wounds tend to form. The more consistently exercisers performed, the higher the plan-tar pressures were at the right second (r = .24, p = .02) and third metatarsal heads (r = .26, p = .01). Findings from this investigation do not refute current ADA recommendations and further intervention studies are needed that are longitudinal and measures WBA more accurately.

The development of a charcot foot after significant weight loss in people with diabetes: three cautionary tales

Medication to aid weight loss and weight loss surgery are becoming more commonly available for people with diabetes. As a result of profound weight loss, diabetes may go into remission and many biochemical and physical parameters improve. However, some of the end organ damage associated with diabetes may not improve, peripheral neuropathy being an example. We present three cases in people with diabetes and pre-existing peripheral neuropathy who had lost significant weight. They became more mobile and developed a Charcot foot despite their diabetes improving significantly. People who have lost significant weight should continue to monitor their feet because the risks of foot disease remain even if diabetes goes into remission.

Towards the generation of a parametric foot model using principal component analysis: A pilot study

There have been many recent developments in patient-specific models with their potential to provide more information on the human pathophysiology and the increase in computational power. However they are not yet successfully applied in a clinical setting. One of the main challenges is the time required for mesh creation, which is difficult to automate. The development of parametric models by means of the Principle Component Analysis (PCA) represents an appealing solution. In this study PCA has been applied to the feet of a small cohort of diabetic and healthy subjects, in order to evaluate the possibility of developing parametric foot models, and to use them to identify variations and similarities between the two populations. Both the skin and the first metatarsal bones have been examined. Besides the reduced sample of subjects considered in the analysis, results demonstrated that the method adopted herein constitutes a first step towards the realization of a parametric foot models for biomechanical analysis. Furthermore the study showed that the methodology can successfully describe features in the foot, and evaluate differences in the shape of healthy and diabetic subjects.

GAIT ANALYSIS DRIVEN 2D FINITE ELEMENT MODEL OF THE NEUROPATHIC HINDFOOT

The diabetic foot is one of the most serious complications of diabetes mellitus and it can lead to foot ulcerations and amputations. Finite element analysis quantifies the loads developed in the different anatomical structures and describes how these affect foot tissue during foot–floor interaction. This approach for the diabetic subjects’ foot could provide valuable information in the process of plantar orthosis fabrication and fit. The purpose of this study was to develop two finite element models of the hindfoot, of healthy and diabetic neuropathic subjects. These models accounts for in vivo kinematics, kinetics, plantar pressure (PP) data and magnetic resonance images. These were acquired during gait analysis on 10 diabetic neuropathics and 10 healthy subjects. Validity of the models has been assessed through comparison between the peak PPs of simulated and experimental data: root mean square error (RMSE) in percentage of the experimental peak value was evaluated. Two different finite elements analysis were performed: subject-specific simulations in terms of both geometry and gait analysis, and by adopting the complete gait analysis dataset as boundary conditions. Model predicted plantar pressures were in good agreement with those experimentally measured. Best agreement was obtained in the subject-specific case (RMSE of 13%).

Intralimb Coordination Patterns in Absent, Mild, and Severe Stages of Diabetic Neuropathy: Looking Beyond Kinematic Analysis of Gait Cycle

AIM

Diabetes Mellitus progressively leads to impairments in stability and joint motion and might affect coordination patterns, mainly due to neuropathy. This study aims to describe changes in intralimb joint coordination in healthy individuals and patients with absent, mild and, severe stages of neuropathy.

METHODS

Forty-seven diabetic patients were classified into three groups of neuropathic severity by a fuzzy model: 18 without neuropathy (DIAB), 7 with mild neuropathy (MILD), and 22 with moderate to severe neuropathy (SVRE). Thirteen healthy subjects were included as controls (CTRL). Continuous relative phase (CRP) was calculated at each instant of the gait cycle for each pair of lower limb joints. Analysis of Variance compared each frame of the CRP time series and its standard deviation among groups (α = 5%).

RESULTS

For the ankle-hip CRP, the SVRE group presented increased variability at the propulsion phase and a distinct pattern at the propulsion and initial swing phases compared to the DIAB and CTRL groups. For the ankle-knee CRP, the 3 diabetic groups presented more anti-phase ratios than the CTRL group at the midstance, propulsion, and terminal swing phases, with decreased variability at the early stance phase. For the knee-hip CRP, the MILD group showed more in-phase ratio at the early stance and terminal swing phases and lower variability compared to all other groups. All diabetic groups were more in-phase at early the midstance phase (with lower variability) than the control group.

CONCLUSION

The low variability and coordination differences of the MILD group showed that gait coordination might be altered not only when frank evidence of neuropathy is present, but also when neuropathy is still incipient. The ankle-knee CRP at the initial swing phase showed distinct patterns for groups from all degrees of neuropathic severity and CTRLs. The ankle-hip CRP pattern distinguished the SVRE patients from other diabetic groups, particularly in the transitional phase from stance to swing.

Skin disorders in diabetes mellitus: an epidemiology and physiopathology review

Skin disorders, usually neglected and frequently underdiagnosed among diabetic patients, are common complications and encounter a broad spectrum of disorders in both type 1 and type 2 diabetes mellitus (DM)-e.g. cutaneous infection, dry skin, pruritus. Skin disorders are highly associated with increased risk of important outcomes, such as skin lesions, ulcerations and diabetic foot, which can lead to major complications and revolve around multifactorial factors besides hyperglycemia and advanced glycation end products. Although diabetic's skin disorders are consistent in the literature, there is limited data regarding early-stage skin disorders in DM patients. Disease control, early-stage treatment (e.g. skin hydration, orthotic devices) and awareness can reduce morbidity of DM patients. Thus, better understanding of the burden of skin disorders in DM patients may raise awareness on prevention and management. Therefore, the aim of this study is to perform a literature review to evaluate the main clinical characteristics and complications of skin disorders in diabetic's patients. Additionally, physiopathology early-stage skin disorders and dermocosmetic management were also reviewed.

Footwear and Foam Surface Alter Gait Initiation of Typical Subjects

Gait initiation is the task commonly used to investigate the anticipatory postural adjustments necessary to begin a new gait cycle from the standing position. In this study, we analyzed whether and how foot-floor interface characteristics influence the gait initiation process. For this purpose, 25 undergraduate students were evaluated while performing a gait initiation task in three experimental conditions: barefoot on a hard surface (barefoot condition), barefoot on a soft surface (foam condition), and shod on a hard surface (shod condition). Two force plates were used to acquire ground reaction forces and moments for each foot separately. A statistical parametric mapping (SPM) analysis was performed in COP time series. We compared the anterior-posterior (AP) and medial-lateral (ML) resultant center of pressure (COP) paths and average velocities, the force peaks under the right and left foot, and the COP integral x force impulse for three different phases: the anticipatory postural adjustment (APA) phase (Phase 1), the swing-foot unloading phase (Phase 2), and the support-foot unloading phase (Phase 3). In Phase 1, significantly smaller ML COP paths and velocities were found for the shod condition compared to the barefoot and foam conditions. Significantly smaller ML COP paths were also found in Phase 2 for the shod condition compared to the barefoot and foam conditions. In Phase 3, increased AP COP velocities were found for the shod condition compared to the barefoot and foam conditions. SPM analysis revealed significant differences for vector COP time series in the shod condition compared to the barefoot and foam conditions. The foam condition limited the impulse-generating capacity of COP shift and produced smaller ML force peaks, resulting in limitations to body-weight transfer from the swing to the support foot. The results suggest that footwear and a soft surface affect COP and impose certain features of gait initiation, especially in the ML direction of Phase 1.

A two-phase model of plantar tissue: a step toward prediction of diabetic foot ulceration

A new computational model, based on the thermodynamically constrained averaging theory, has been recently proposed to predict tumor initiation and proliferation. A similar mathematical approach is proposed here as an aid in diabetic ulcer prevention. The common aspects at the continuum level are the macroscopic balance equations governing the flow of the fluid phase, diffusion of chemical species, tissue mechanics, and some of the constitutive equations. The soft plantar tissue is modeled as a two-phase system: a solid phase consisting of the tissue cells and their extracellular matrix, and a fluid one (interstitial fluid and dissolved chemical species). The solid phase may become necrotic depending on the stress level and on the oxygen availability in the tissue. Actually, in diabetic patients, peripheral vascular disease impacts tissue necrosis; this is considered in the model via the introduction of an effective diffusion coefficient that governs transport of nutrients within the microvasculature. The governing equations of the mathematical model are discretized in space by the finite element method and in time domain using the θ-Wilson Method. While the full mathematical model is developed in this paper, the example is limited to the simulation of several gait cycles of a healthy foot.

Plantar pressure in diabetic peripheral neuropathy patients with active foot ulceration, previous ulceration and no history of ulceration: a meta-analysis of observational studies

Aims

Elevated dynamic plantar pressures are a consistent finding in diabetes patients with peripheral neuropathy with implications for plantar foot ulceration. This meta-analysis aimed to compare the plantar pressures of diabetes patients that had peripheral neuropathy and those with neuropathy with active or previous foot ulcers.

Methods

Published articles were identified from Medline via OVID, CINAHL, SCOPUS, INFORMIT, Cochrane Central EMBASE via OVID and Web of Science via ISI Web of Knowledge bibliographic databases. Observational studies reporting barefoot dynamic plantar pressure in adults with diabetic peripheral neuropathy, where at least one group had a history of plantar foot ulcers were included. Interventional studies, shod plantar pressure studies and studies not published in English were excluded. Overall mean peak plantar pressure (MPP) and pressure time integral (PTI) were primary outcomes. The six secondary outcomes were MPP and PTI at the rear foot, mid foot and fore foot. The protocol of the meta-analysis was published with PROPSERO, (registration number CRD42013004310).

Results

Eight observational studies were included. Overall MPP and PTI were greater in diabetic peripheral neuropathy patients with foot ulceration compared to those without ulceration (standardised mean difference 0.551, 95% CI 0.290–0.811, p<0.001; and 0.762, 95% CI 0.303–1.221, p = 0.001, respectively). Sub-group analyses demonstrated no significant difference in MPP for those with neuropathy with active ulceration compared to those without ulcers. A significant difference in MPP was found for those with neuropathy with a past history of ulceration compared to those without ulcers; (0.467, 95% CI 0.181– 0.753, p = 0.001). Statistical heterogeneity between studies was moderate.

Conclusions

Plantar pressures appear to be significantly higher in patients with diabetic peripheral neuropathy with a history of foot ulceration compared to those with diabetic neuropathy without a history of ulceration. More homogenous data is needed to confirm these findings.

Effects of strengthening, stretching and functional training on foot function in patients with diabetic neuropathy: results of a randomized controlled trial

Background

Foot musculoskeletal deficits are seldom addressed by preventive medicine despite their high prevalence in patients with diabetic polyneuropathy.

AIM: To investigate the effects of strengthening, stretching, and functional training on foot rollover process during gait.

Methods

A two-arm parallel-group randomized controlled trial with a blinded assessor was designed. Fifty-five patients diagnosed with diabetic polyneuropathy, 45 to 65 years-old were recruited. Exercises for foot-ankle and gait training were administered twice a week, for 12 weeks, to 26 patients assigned to the intervention group, while 29 patients assigned to control group received recommended standard medical care: pharmacological treatment for diabetes and foot care instructions. Both groups were assessed after 12 weeks, and the intervention group at follow-up (24 weeks). Primary outcomes involved foot rollover changes during gait, including peak pressure (PP). Secondary outcomes involved time-to-peak pressure (TPP) and pressure–time integral (PTI) in six foot-areas, mean center of pressure (COP) velocity, ankle kinematics and kinetics in the sagittal plane, intrinsic and extrinsic muscle function, and functional tests of foot and ankle.

Results

Even though the intervention group primary outcome (PP) showed a not statistically significant change under the six foot areas, intention-to-treat comparisons yielded softening of heel strike (delayed heel TPP, p=.03), better eccentric control of forefoot contact (decrease in ankle extensor moment, p<.01; increase in function of ankle dorsiflexion, p<.05), earlier lateral forefoot contact with respect to medial forefoot (TPP anticipation, p<.01), and increased participation of hallux (increased PP and PTI, p=.03) and toes (increase in PTI, medium effect size). A slower COP mean velocity (p=.05), and an increase in overall foot and ankle function (p<.05) were also observed. In most cases, the values returned to baseline after the follow-up (p<.05).

Conclusions

Intervention discreetly changed foot rollover towards a more physiological process, supported by improved plantar pressure distribution and better functional condition of the foot ankle complex. Continuous monitoring of the foot status and patient education are necessary, and can contribute to preserving the integrity of foot muscles and joints impaired by polyneuropathy.

Trial registration

ClinicalTrials.gov Identifier: NCT01207284, registered in 20^th September 2010.

The effect of prior compression tests on the plantar soft tissue compressive and shear properties

Changes in the shear plantar soft tissue properties with diabetes are believed to play a role in plantar ulceration, yet little is known about these properties. Our group recently conducted shear tests on specimens previously tested in compression to fully characterize the tissue under both these loading modes. However, previously tested specimens may not necessarily provide representative mechanical properties as prior testing may have altered the tissue to an unknown extent. Thus, the purpose of this study was to test the effect of prior compression testing on both the plantar soft tissue shear and compressive properties using paired specimens. First, one specimen from each pair was subject to compression using our standard protocol with modifications to compare compressive properties before and after the protocol while the other specimen from each pair was left untested. Then, both specimens (i.e., one previously compression tested and one previously untested) were subject to shear testing. The results indicate that prior compression testing may affect the tissue compressive properties by reducing peak stress and modulus; however, additional testing is needed since these results were likely confounded by stress softening effects. In contrast, neither the elastic nor the viscoelastic plantar soft tissue shear properties were affected by prior testing in compression, indicating that previously compression tested specimens should be viable for use in future shear tests. However, these results are limited given the small sample size of the study and the fact that only nondiabetic specimens were examined.

How effective is orthotic treatment in patients with recurrent diabetic foot ulcers?

BACKGROUND

We assessed the efficacy of customized foot orthotic therapy by comparing reulceration rates, minor amputation rates, and work and daily living activities before and after therapy. Peak plantar pressures and peak plantar impulses were compared with the patients not wearing and wearing their prescribed footwear.

METHODS

One hundred seventeen patients with diabetes were prescribed therapeutic insoles and footwear based on the results of a detailed biomechanical study and were followed for 2 years. All of the patients had a history of foot ulcers, but none had undergone previous orthotic therapy.

RESULTS

Before treatment, the reulceration rate was 79% and the amputation rate was 54%. Two years after the start of orthotic therapy, the reulceration rate was 15% and the amputation rate was 6%. Orthotic therapy reduced peak plantar pressures in patients with reulcerations and in those without (P < .05), although a significant decrease in peak plantar impulses was achieved only in patients not experiencing reulceration. Sick leave was reduced from 100% to 26%.

CONCLUSIONS

Personalized orthotic therapy targeted at reducing plantar pressures by off-loading protects high-risk patients against reulceration. Treatment reduced the reulceration rate and peak plantar pressures, leading to patients' return to work or other activities.

Classification of forefoot plantar pressure distribution in persons with diabetes: a novel perspective for the mechanical management of diabetic foot?

Background

The aim of this study was to identify groups of subjects with similar patterns of forefoot loading and verify if specific groups of patients with diabetes could be isolated from non-diabetics.

Methodology/Principal Findings

Ninety-seven patients with diabetes and 33 control participants between 45 and 70 years were prospectively recruited in two Belgian Diabetic Foot Clinics. Barefoot plantar pressure measurements were recorded and subsequently analysed using a semi-automatic total mapping technique. Kmeans cluster analysis was applied on relative regional impulses of six forefoot segments in order to pursue a classification for the control group separately, the diabetic group separately and both groups together. Cluster analysis led to identification of three distinct groups when considering only the control group. For the diabetic group, and the computation considering both groups together, four distinct groups were isolated. Compared to the cluster analysis of the control group an additional forefoot loading pattern was identified. This group comprised diabetic feet only. The relevance of the reported clusters was supported by ANOVA statistics indicating significant differences between different regions of interest and different clusters.

Conclusion/s Significance

There seems to emerge a new era in diabetic foot medicine which embraces the classification of diabetic patients according to their biomechanical profile. Classification of the plantar pressure distribution has the potential to provide a means to determine mechanical interventions for the prevention and/or treatment of the diabetic foot.