Plantar temperatures in stance position: A comparative study with healthy volunteers and diabetes patients diagnosed with sensoric neuropathy

Pressure-Induced Microvascular Reactivity With Whole Foot Loading Is Unique Across the Human Foot Sole

BACKGROUND

Foot sole plantar pressure generates transient but habitual cutaneous ischemia, which is even more exacerbated in atypical gait patterns. Thus, adequate post-occlusive reactive hyperaemia (PORH) is necessary to maintain skin health. Plantar pressure regional variance during daily tasks potentially generates region-specific PORH, crucial for ischemic defence.

AIMS

The current work investigated regional PORH across the human foot sole resulting from stance-like loading.

MATERIALS & METHODS

A loading device equipped with an in-line laser speckle contrast imager measured blood flux before, during, and after whole-foot loading for 2 and 10 min durations at 15% and 50% body weight. Flux was compared between six regions: the heel, lateral arch, medial arch, and fifth, third, and first metatarsals (MT).

RESULTS

Baseline flux was significantly greater in the 1MT and 3MT than all other regions. Loading occluded the heel, 5MT and 3MT more than all other regions. Regional PORH peak, time to peak, area under the curve, and recovery rate were ranked between regions.

DISCUSSION

The 3MT, followed by 5MT, overall had the strongest PORH response, suggesting a heightened protection against ischemia compared to other regions.

CONCLUSION

This work highlights regional variations within a healthy foot, providing a framework for future ulcer risk assessments and interventions to preserve foot health.

Thermography, Temperature, Pressure Force Distribution and Physical Activity in Diabetic Foot: A Systematic Review

One of the most significant complications of diabetes mellitus is diabetic sensory neuropathy. A reduction in pain perception increases the risk of diabetic patients developing foot ulcers and requiring amputation, which in turn results in impaired mobility and a diminished quality of life. Despite recent advances in our understanding of the aetiology of diabetic foot ulcers (DFUs), there remains a significant gap in the clinical prevention and management of these ulcers. Given that inflammation represents the initial stage in the formation of skin wounds, the utilisation of infrared thermography for the early detection of inflammatory tissue, the analysis of plantar pressures and the monitoring of controlled physical activity (PA) may facilitate the close observation of plantar skin alterations that are susceptible to the development of DFUs, thereby enabling the implementation of timely interventions such as personalised PA for these patients. It is recommended that an integrated approach be adopted which encompasses the utilisation of all emerging technologies in order to enhance outcomes in the prevention and management of DFUs. The aim of this study is to examine the existing literature on the relationship between temperature, pressure and physical activity in the diabetic foot. To this end, a systematic review was conducted in accordance with the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) format across the PubMed, Scopus and Web of Science databases, with no temporal restriction. A total of 14 studies were included in the review. The use of infrared thermography for the early detection of inflammatory tissue, plantar pressures and the monitoring of controlled PA can facilitate the close monitoring of changes that may pose a risk for the formation of UFDs and provide timely intervention, thereby personalising the PA of the diabetic patient.

Effect of different inner pressures of air insoles and walking durations on plantar pressure time integral

Air insoles have provided insights for reducing the risk of diabetic foot ulcers (DFU). The pressure time integral (PTI) is an effective assessment that considers the time effect in various physical activities. We investigated the interactions between three different insole inner pressures (80, 160, and 240 mmHg) and two walking durations (10 and 20 min). The big toe (T1), first metatarsal head (M1), and second metatarsal head (M2) were investigated in 13 healthy participants. One-way analysis of variance (ANOVA) showed that the effects of each insole inner pressure significantly differed (P < 0.05) with a 10 min walking duration. The PTI values resulting from 80 mmHg in M2 (38.4 ± 3.8, P = 0.002) and 160 mmHg in M1 (44.3 ± 4.3, P = 0.027) were lower than those from 240 mmHg. Additionally, the paired t test showed that the effects of each walking duration were also considerably different at 160 mmHg. The PTI at 10 min was lower than that at 20 min in M1 (44.31 ± 4.31, P = 0.015) and M2 (47.14 ± 5.27, P = 0.047). Thus, we suggest that walking with a pressure of 160 mmHg for 10 min has a lower risk of DFU.

Mechanoreceptor sensory feedback is impaired by pressure induced cutaneous ischemia on the human foot sole and can predict cutaneous microvascular reactivity

Introduction

The foot sole endures high magnitudes of pressure for sustained periods which results in transient but habitual cutaneous ischemia. Upon unloading, microvascular reactivity in cutaneous capillaries generates an influx of blood flow (PORH: post-occlusive reactive hyperemia). Whether pressure induced cutaneous ischemia from loading the foot sole impacts mechanoreceptor sensitivity remains unknown.

Methods

Pressure induced ischemia was attained using a custom-built-loading device that applied load to the whole right foot sole at 2 magnitudes (15 or 50% body weight), for 2 durations (2 or 10 minutes) in thirteen seated participants. Mechanoreceptor sensitivity was assessed using Semmes-Weinstein monofilaments over the third metatarsal (3MT), medial arch (MA), and heel. Perceptual thresholds (PT) were determined for each site prior to loading and then applied repeatedly to a metronome to establish the time course to return to PT upon unload, defined as PT recovery time. Microvascular flux was recorded from an in-line laser speckle contrast imager (FLPI-2, Moor Instruments Inc.) to establish PORH peak and recovery rates at each site.

Results

PT recovery and PORH recovery rate were most influenced at the heel and by load duration rather than load magnitude. PT recovery time at the heel was significantly longer with 10 minutes of loading, regardless of magnitude. Heel PORH recovery rate was significantly slower with 10minutes of loading. The 3MT PT recovery time was only longer after 10 minutes of loading at 50% body weight. Microvascular reactivity or sensitivity was not influenced with loading at the MA. A simple linear regression found that PORH recovery rate could predict PT recovery time at the heel (R2=0.184, p<0.001).

Conclusion

In populations with degraded sensory feedback, such as diabetic neuropathy, the risk for ulcer development is heightened. Our work demonstrated that prolonged loading in healthy individuals can impair skin sensitivity, which highlights the risks of prolonged loading and is likely exacerbated in diabetes. Understanding the direct association between sensory function and microvascular reactivity in age and diabetes related nerve damage, could help detect early progressions of neuropathy and mitigate ulcer development.

Preventative Sensor-Based Remote Monitoring of the Diabetic Foot in Clinical Practice

Diabetes and its complications, particularly diabetic foot ulcers (DFUs), pose significant challenges to healthcare systems worldwide. DFUs result in severe consequences such as amputation, increased mortality rates, reduced mobility, and substantial healthcare costs. The majority of DFUs are preventable and treatable through early detection. Sensor-based remote patient monitoring (RPM) has been proposed as a possible solution to overcome limitations, and enhance the effectiveness, of existing foot care best practices. However, there are limited frameworks available on how to approach and act on data collected through sensor-based RPM in DFU prevention. This perspective article offers insights from deploying sensor-based RPM through digital DFU prevention regimens. We summarize the data domains and technical architecture that characterize existing commercially available solutions. We then highlight key elements for effective RPM integration based on these new data domains, including appropriate patient selection and the need for detailed clinical assessments to contextualize sensor data. Guidance on establishing escalation pathways for remotely monitored at-risk patients and the importance of predictive system management is provided. DFU prevention RPM should be integrated into a comprehensive disease management strategy to mitigate foot health concerns, reduce activity-associated risks, and thereby seek to be synergistic with other components of diabetes disease management. This integrated approach has the potential to enhance disease management in diabetes, positively impacting foot health and the healthspan of patients living with diabetes.

Monitoring of Dynamic Plantar Foot Temperatures in Diabetes with Personalised 3D-Printed Wearables

Diabetic foot ulcers (DFUs) are a life-changing complication of diabetes that can lead to amputation. There is increasing evidence that long-term management with wearables can reduce incidence and recurrence of this condition. Temperature asymmetry measurements can alert to DFU development, but measurements of dynamic information, such as rate of temperature change, are under investigated. We present a new wearable device for temperature monitoring at the foot that is personalised to account for anatomical variations at the foot. We validate this device on 13 participants with diabetes (no neuropathy) (group name D) and 12 control participants (group name C), during sitting and standing. We extract dynamic temperature parameters from four sites on each foot to compare the rate of temperature change. During sitting the time constant of temperature rise after shoe donning was significantly (p < 0.05) faster at the hallux (p = 0.032, 370.4 s (C), 279.1 s (D)) and 5th metatarsal head (p = 0.011, 481.9 s (C), 356.6 s (D)) in participants with diabetes compared to controls. No significant differences at the other sites or during standing were identified. These results suggest that temperature rise time is faster at parts of the foot in those who have developed diabetes. Elevated temperatures are known to be a risk factor of DFUs and measurement of time constants may provide information on their development. This work suggests that temperature rise time measured at the plantar surface may be an indicative biomarker for differences in soft tissue biomechanics and vascularisation during diabetes onset and progression.