Plantar pressure in off-loading devices used in diabetic ulcer treatment

In-shoe plantar pressure measurement technologies for the diabetic foot: A systematic review

Introduction

Loss of cutaneous protective sensation and high plantar pressures increase the risk for diabetic foot patients. Trauma and ulceration are imminent threats, making assessment and monitoring essential. This systematic review aims to identify systems and technologies for measuring in-shoe plantar pressures, focusing on the at-risk diabetic foot population.

Methods

A systematic search was conducted across four electronic databases (Scopus, Web of Science, PubMed, Oxford Journals) using PRISMA methodology, covering articles published in English from 1979 to 2024. Only studies addressing systems or sensors exclusively measuring plantar pressures inside the shoe were included.

Results

A total of 87 studies using commercially available devices and 45 articles proposing new systems or sensors were reviewed. The prevailing market offerings consist mainly of instrumented insoles. Emerging technologies under development often feature configurations with four, six or eight resistive sensors strategically placed within removable insoles. Despite some variability due to the inherent heterogeneity of human gait, these devices assess plantar pressure, although they present significant differences between them in measurement results. Individuals with diabetic foot conditions appears exhibit elevated plantar pressures, with reported peak pressures reaching approximately 1000 kPa. The results also showed significant differences between the diabetic and non-diabetic groups.

Conclusion

Instrumented insoles, particularly those incorporating resistive sensor technology, dominate the field. Systems employing eight sensors at critical locations represent a pragmatic approach, although market options extend to systems with up to 960 sensors. Differences between devices can be a critical factor in measurement and highlights the importance of individualized patient assessment using consistent measurement devices.

The pressure time integral: An underused, clinically significant parameter as a determinant of neuropathic ulceration in diabetes

BACKGROUND

The purpose of this study was to evaluate plantar pressure dynamics in the occurrence of active diabetic neuropathic ulceration (DNU) and any changes in loadings occurring in individuals with a history of diabetic neuropathic ulceration (DHNU). Since current gold standard offloading strategies are not producing desirable healing outcomes and optimum ulcer prevention, this study aimed to better understand the effect of diabetic peripheral neuropathy (DPN) and ulceration on mean peak plantar pressure (MPPP) and pressure-time integral (PTI) changes.

RESEARCH QUESTION

Is there a redistribution of plantar pressure during gait in the presence of active and history of diabetic neuropathic ulceration?

METHODS

A prospective, cross-sectional study was conducted, in which, eighty adult participants were divided into four groups, namely, the DM, DPN, DNU and DHNU groups. Participants were instructed to walk barefoot over a Tekscan HR Mat™ at self-selected speed. MPPP and PTI data were analysed under five forefoot anatomical landmarks and compared between individuals with and without active neuropathic ulceration.

RESULTS

Minimal MPPP significant changes were observed between ulcerated and non-ulcerated groups, however, PTI values were significantly increased in the ulcerated groups under all plantar ulceration regions. No significant plantar pressure differences were observed between the DNU and DHNU groups. Logistic regression tests demonstrated that as PTIs under the hallux increase, the likelihood of an individual living with DPN developing ulceration increases.

SIGNIFICANCE

A significant increase in PTI values in the presence of ulceration highlights the importance of evaluating the duration of loads under forefoot regions during gait rather than just focusing on the magnitude of pressures during ulcer management and prevention. Moreover, results show that PTI values remain high in the presence of a history of neuropathic ulceration, possibly demonstrating the value of PTI as a clinical tool over MPPP in the assessment of the high-risk diabetic foot.

Differences in adherence to using removable cast walker treatment during daytime and nighttime weight-bearing activities in people with diabetes-related foot ulcers

AIMS

Patients' adherence to using knee-high offloading treatment is critical to effective healing of diabetes-related foot ulcers (DFUs). Previous studies have found that patients generally have low adherence to using removable knee-high offloading treatments, yet no study has investigated whether their adherence differs during daytime and nighttime. This study aimed to investigate the levels and factors associated with adherence to using knee-high removable cast walker (RCW) treatment during daytime and nighttime weight-bearing activities in people with DFUs.

METHODS

This was a secondary analysis of data collected from a multi-centre cross-sectional study investigating adherence to using knee-high RCWs among 57 participants with DFUs. All participants had multiple socio-demographic, physiological and psychosocial factors collected, before having their adherence to using RCWs during weight-bearing activity monitored over a 1-week period using the dual activity monitor method. Adherence data were categorised into daytime (06:00-18:00) and nighttime (18:00-06:00) periods and calculated separately. Multiple linear regression was used to identify factors associated with daytime and nighttime adherence.

RESULTS

Mean adherence to using RCW during weight-bearing activities in people with DFUs was higher during daytime compared with nighttime [39.9% (SD = 18.9) versus 20.4% (SD = 16.7), p < 0.001]. Factors independently associated with lower adherence during daytime were being male, longer diabetes duration, not having peripheral artery disease (PAD), and higher perceived RCW heaviness. Factors associated with lower adherence during nighttime were higher mean daytime steps, not having retinopathy and having dyslipidaemia.

CONCLUSIONS

Adherence to using RCWs during weight-bearing activities reduced significantly at nighttime compared with daytime among people with DFUs, and this was associated with different factors. Interventions to improve adherence, in research and clinical practice, should incorporate methods to target daytime or nighttime adherence specifically.

The Effects of Blue Light on Human Fibroblasts and Diabetic Wound Healing

Diabetes is a serious threat to global health and is among the top 10 causes of death. The Diabetic foot ulcer (DFU) is among the most common and severe complications of the disease. Bacterial infections are common; therefore, timely aggressive management, using multidisciplinary management approaches is needed to prevent complications, morbidity, and mortality, particularly in view of the growing cases of antibiotic-resistant bacteria. Photobiomodulation (PBM) involves the application of low-level light at specific wavelengths to induce cellular photochemical and photophysical responses. Red and near-infrared (NIR) wavelengths have been shown to be beneficial, and recent studies indicate that other wavelengths within the visible spectrum could be helpful as well, including blue light (400–500 nm). Reports of the antimicrobial activity and susceptibility of blue light on several strains of the same bacterium show that many bacteria are less likely to develop resistance to blue light treatment, meaning it is a viable alternative to antibiotic therapy. However, not all studies have shown positive results for wound healing and fibroblast proliferation. This paper presents a critical review of the literature concerning the use of PBM, with a focus on blue light, for tissue healing and diabetic ulcer care, identifies the pros and cons of PBM intervention, and recommends the potential role of PBM for diabetic ulcer care.

The impact of topical phenytoin loaded nanostructured lipid carriers in diabetic foot ulceration

OBJECTIVE

The aim of this study is to develop, and characterize nanostructured lipid carriers (NLCs) of phenytoin (PHT) in order to improve its entrapment efficiency and sustained release to improve the healing process.

METHODS

Twenty-seven patients with neuropathic diabetic foot ulceration (DFU) were enrolled in this study. Patients were comparable regarding size, grading of ulcer and control of diabetes with no major deformity. All patients were managed by weekly sharp debridement if indicated and offloaded with cast shoes. They were equally divided into three groups: PHT-NLC-hydrogel (0.5%w/v), phenytoin hydrogel (0.5%w/v) and blank hydrogel groups. Changes in wound area were monitored over 2 months.

RESULTS

Baseline wound area of PHT-NLC, PHT and blank hydrogels were 5.50 ± 3.66, 3.94 ± 1.86 and 5.36 ± 2.14 cm², respectively. Ulcers treated with PHT-NLC hydrogel showed smaller wound area compared to control groups (ρ < 0.05). The overall reduction in ulcer size were 95.82 ± 2.22% for PHT-NLC-hydrogel in comparison to 47.10 ± 4.23% and -34.91 ± 28.33% for PHT and blank-hydrogel (ρ < 0.001), respectively.

CONCLUSION

PHT-NLC hydrogel speeds up the healing process of the DFU without adverse effects when compared to the positive and negative control hydrogels. Moreover, the study can open a window for topical application of NLCs loaded with PHT in the treatment of numerous dermatological disorders that resist conventional treatment.

KEY MESSAGE

The delivery of drug molecules and their localization into the skin is the main purpose of the topical dosage forms. In this manuscript, the impact of topical phenytoin loaded nanostructured lipid carrier in improving wound healing in patients with neuropathic diabetic foot ulceration was investigated. Phenytoin loaded nanostructured lipid carrier dressing was found to be more effective than phenytoin hydrogel at the same concentration in healing of neuropathic diabetic foot ulcer.

The lived experience of people with diabetes using off-the-shelf prescription footwear in Singapore: a qualitative study using interpretative phenomenological analysis

BACKGROUND

Diabetic foot ulceration (DFUs) is increasingly prevalent in Singapore. Appropriate management is important since DFU brings with it an associated risk for lower limb amputations, high morbidity rates and costs. Footwear prescription has been a part of clinical guidelines to manage DFUs. However, adherence to prescription footwear is typically poor amongst patients. Reasons for this have been explored in Northern American and Western European studies, but not in Singapore's context. As cultural and climate differences limit transferability of findings from existing studies to individuals in Singapore, this study aims to explore the lived experiences of participants with diabetes using prescription footwear in Singapore.

METHODS

This was a qualitative study using interpretative phenomenological analysis (IPA) to understand some people's personal experience of using off the shelf prescription footwear. A total of 8 people with diabetes who received prescription footwear as part of their diabetic foot management were recruited. All participants provided written consent and took part in a semi-structured interview lasting up to an hour. Interviews were digitally recorded, transcribed and analysed using an IPA approach.

FINDINGS AND DISCUSSION

The analysis identified the super-ordinate themes of 1) security and 2) acceptance with sub-themes of 1.1) risk and 1.2) protection and 2.1) personal and social acceptance and 2.2) social and cultural acceptance respectively that inter-related to influence how participants' made footwear decisions. This process of evaluation was portrayed to be a fluctuant one, making it difficult to predict yet necessary to understand. A modified seesaw model of adherence is suggested to explain this decision-making process.

CONCLUSIONS

The complex manner by which participants grappled with security and acceptance is often overlooked when footwear is prescribed, highlighting a need for a more collaborative clinician-patient partnership for these issues to surface in clinical practice. Furthermore, prescription footwear should be seen more holistically. Empowering patients with choice to select from a range of therapeutic yet normalised footwear could increase the level of security and acceptance they experience with its use.

Effect of different casting design characteristics on offloading the diabetic foot

BACKGROUND

Non-removable knee-high devices, such as a total contact cast (TCC), are recommended for offloading diabetic plantar forefoot ulcers. However, it is insufficiently known how each of the different design characteristics of these devices contribute to offloading the diabetic foot.

RESEARCH QUESTION

What is the offloading effect of the different design characteristics that make up a non-removable knee-high cast for people with diabetes and active or previous plantar forefoot ulcers?

METHODS

Sixteen persons with diabetes, peripheral neuropathy and a healed or active plantar forefoot ulcer had their plantar pressures measured during walking in a non-removable knee-high device (TCC), in that device made removable (BTCC), in that device made below-ankle (cast shoe), in that cast shoe worn with a different walking sole and in a newly made cast shoe without a custom-moulded foot-device interface. Peak pressures, force-time integral, and perceived walking comfort were assessed.

RESULTS

Compared with the BTCC, peak pressures in the TCC were 47% (P = 0.028), 26% (P = 0.003) and 15% (P = 0.050) lower at the hallux, midfoot and (previous) ulcer location, respectively. Compared to the cast shoe, peak pressures in the BTCC were 39-43% and 47% (both P < 0.001) lower in the forefoot regions and (previous) ulcer location, respectively. The total force-time integral was 21% and 11% (P < 0.007) lower in the TCC and BTCC compared to the cast shoe. Perceived walking comfort was 5.6 in the TCC and 6.5 in the BTCC (P = 0.037). Effects of the other design characteristics (i.e. walking sole and plantar moulding) were non-significant.

SIGNIFICANCE

The TCC gives superior offloading, mostly because of being a knee-high and non-removable device, providing an optimal 'shaft effect'. The TCC does, however, negatively affect walking comfort. These results aid decision-making in offloading diabetic plantar forefoot ulcers.

The efficacy of removable devices to offload and heal neuropathic plantar forefoot ulcers in people with diabetes: a single-blinded multicentre randomised controlled trial

Non-removable offloading is the 'gold standard' treatment for neuropathic diabetic plantar forefoot ulcers. However, removable offloading is the common 'standard of care'. We compared three removable offloading devices for ulcer healing efficacy. In this multicentre, randomised controlled trial, 60 persons with neuropathic diabetic plantar forefoot ulcers were randomly assigned to wear a custom-made knee-high cast [BTCC (bivalved TCC)], custom-made ankle-high cast shoe or a prefabricated ankle-high forefoot-offloading shoe (FOS). Primary outcome was healing at 12 weeks. Dynamic plantar pressures, daily stride count and treatment adherence were assessed on a randomly selected subset (n = 35). According to intention-to-treat analysis, 58% of patients healed with BTCC [OR 0·77 (95% CI 0·41-1·45) versus FOS], 60% with cast shoe [OR 0·81 (95% CI 0·44-1·49) versus FOS] and 70% with FOS (P = 0·70). Mean ± SD peak pressure in kPa at the ulcer site was 81 ± 55 for BTCC, 176 ± 80 for cast shoe and 107 ± 52 for FOS (P = 0·005); stride count was 4150 ± 1626, 3514 ± 1380 and 4447 ± 3190, respectively (P = 0·71); percentage of 2-week intervals that patients wore the device <50% of time was 17·3%, 5·2% and 4·9%, respectively. Non-significant differences in healing efficacy between the three devices suggest that, when non-removable offloading is contraindicated or not available, each can be used for plantar forefoot ulcer offloading. Efficacy is lower than previously found for non-removable offloading maybe because suboptimal adherence and high stride count expose the patient to high repetitive stresses. These factors should be carefully considered in decision making regarding ulcer treatment.

The Role of Pressure Offloading on Diabetic Foot Ulcer Healing and Prevention of Recurrence

BACKGROUND

An increased plantar pressure is a causative factor in the development of plantar foot ulcers in people with diabetes mellitus, and ulcers are a precursor of lower extremity amputation.

METHODS

In this article, the evidence is reviewed that relieving areas of increased plantar pressure (ie, offloading) can heal plantar foot ulcers and prevent their recurrence.

RESULTS

Noninfected, nonischemic neuropathic plantar forefoot ulcers should heal in 6 to 8 weeks with adequate offloading. Recent meta-analyses and systematic reviews show that nonremovable knee-high devices are most effective. This is probably because they eliminate the problem of nonadherence with the use of a removable device. Studies show a large discrepancy between evidence-based recommendations on offloading and what is used in clinical practice. Many clinics continue to use methods that are less effective or have not been proven to be effective, while ignoring evidence-based methods. Strategies are proposed to address this issue, notably the adoption and implementation of recent international guidelines by professional societies and a stronger focus of clinicians on expedited healing. For the prevention of plantar foot ulcer recurrence in high-risk patients, 2 recent trials have shown that the incidence of recurrence can be significantly reduced with custom-made footwear that has a demonstrated pressure-relieving effect through guidance by plantar pressure measurements, under the condition that the footwear is worn.

CONCLUSION

This review helps to inform clinicians about effective offloading treatment for healing plantar foot ulcers and preventing their recurrence.

Total contact cast wall load in patients with a plantar forefoot ulcer and diabetes

BACKGROUND

The total contact cast (TCC) is an effective intervention to reduce plantar pressure in patients with diabetes and a plantar forefoot ulcer. The walls of the TCC have been indirectly shown to bear approximately 30 % of the plantar load. A new direct method to measure inside the TCC walls with capacitance sensors has shown that the anterodistal and posterolateral-distal regions of the lower leg bear the highest load. The objective of this study was to directly measure these two regions in patients with Diabetes and a plantar forefoot ulcer to further understand the mechanism of pressure reduction in the TCC.

METHODS

A TCC was applied to 17 patients with Diabetes and a plantar forefoot ulcer. TCC wall load (contact area, peak pressure and max force) at the anterodistal and posterolateral-distal regions of the lower leg were evaluated with two capacitance sensor strips measuring 90 cm(2) (pliance®, novel GmbH, Germany). Plantar load (contact area, peak pressure and max force) was measured with a capacitance sensor insole (pedar®, novel GmbH, Germany) placed inside the TCC. Both pedar® and pliance® collected data simultaneously at a sampling rate of 50Hz synchronised to heel strike. The magnitude of TCC wall load as a proportion of plantar load was calculated. The TCC walls were then removed to determine the differences in plantar loading between the TCC and the cut down shoe-cast for the whole foot, rearfoot, midfoot and forefoot (region of interest).

RESULTS

TCC wall load was substantial. The anterodistal lower leg recorded 48 % and the posterolateral-distal lower leg recorded 34 % of plantar contact area. The anterodistal lower leg recorded 28 % and the posterolateral-distal lower leg recorded 12 % of plantar peak pressure. The anterodistal lower leg recorded 12 % and the posterolateral-distal lower leg recorded 4 % of plantar max force. There were significant differences in plantar load between the TCC and the cut down shoe-cast for the whole foot, rearfoot, midfoot and forefoot (region of ulcer). Contact area significantly increased by 5 % beneath the whole foot, 8 % at the midfoot and 6 % at the forefoot in the shoe-cast (p < 0.05). Peak pressure significantly increased by 8 % beneath the midfoot and 13 % at the forefoot in the shoe-cast (p < 0.05). Max force significantly increased 6 % beneath the midfoot in the (shoe-cast p < 0.05).

CONCLUSION

In patients with diabetes and a plantar forefoot ulcer, the walls of the TCC bear considerable load. Reduced plantar contact area in the TCC compared to the shoe-cast suggests that the foot is suspended by the considerable load bearing capacity of the walls of the TCC which contributes mechanically to the pressure reduction and redistribution properties of the TCC.

Custom Orthotics to Mitigate Effects of Chemotherapy-induced Peripheral Neuropathy

Background

Chemotherapy-induced peripheral neuropathy (CIPN) is a complication commonly involving extremities characterized by dysthesias. Given the predilection towards diminished proprioceptive feedback, balance and gait deficits often result, leading to an increase in falls risk. To date there is no published evidence to support the use of orthotics in the treatment of balance dysfunction secondary to CIPN.

Purpose

This report describes custom foot orthotics with a closed cell foam overlay to improve postural stability and mobility in CIPN.

Case Description

An individual experiencing progressive balance dysfunction was provided orthotics when standard interventions were not effective. Expectations were that improved joint contact via midfoot compression and improved bony alignment would alter proprioceptive feedback throughout the kinetic chain and result in greater postural stability. Finding a cosmetically appealing shoe to provide sufficient tactile cues and support, without undue pressure challenged clinical decision making.

Outcome Measures

Computerized dynamic posturography and accelerometry were used to measure postural sway. Three conditions (barefoot, shoes only, and shoe plus orthotics) were tested to differentiate effects of orthotics and shoes. With orthotic use measures of sway velocity and area improved as did his ability to stand unassisted. Timed Up and Go and gait speed measures also improved.

The management of diabetic foot ulcers through optimal off-loading: building consensus guidelines and practical recommendations to improve outcomes

BACKGROUND

We sought to develop a consensus statement for the use of off-loading in the management of diabetic foot ulcers (DFUs).

METHODS

A literature search of PubMed for evidence regarding off-loading of DFUs was initially conducted, followed by a meeting of authors on March 15, 2013, in Philadelphia, Pennsylvania, to draft consensus statements and recommendations using the GRADE (Grading of Recommendations Assessment, Development, and Evaluation) approach to assess quality of evidence and develop strength of recommendations for each consensus statement.

RESULTS

Evidence is clear that adequate off-loading increases the likelihood of DFU healing and that increased clinician use of effective off-loading is necessary. Recommendations are included to guide clinicians on the optimal use of off-loading based on an initial comprehensive patient/wound assessment and the necessity to improve patient adherence with off-loading devices.

CONCLUSIONS

The likelihood of DFU healing is increased with off-loading adherence, and, current evidence favors the use of nonremovable casts or fixed ankle walking braces as optimum off-loading modalities. There currently exists a gap between what the evidence supports regarding the efficacy of DFU off-loading and what is performed in clinical practice despite expert consensus on the standard of care.

A comparison of two total contact cast constructs with variable body mass

OBJECTIVE

There is a growing body of evidence implicating obesity as having a negative effect on the development and treatment of diabetic foot disease. The aim of this study was to increase the body of knowledge on the effects of obesity on foot function, specifically as it relates to peak plantar pressures in the total contact cast (TCC). Our investigational objectives were to compare the effect of two different TCC designs on mean peak plantar pressures, and to evaluate the efficacy of two TCC constructs with increasing body mass.

METHOD

The primary outcome measure was mean peak plantar pressure in the heel, midfoot, forefoot and first metatarsal as measured with an in-shoe pressure measurement system. The variables were patient weight (from 'normal' body mass index (BMI) to 'overweight', 'obese' and 'morbidly obese') and the TCC construct (with both a standard and alternate cast design). The standard TCC is considered the gold standard for off-loading of the diabetic foot. The alternate TCC was designed to use the essential offloading component of the traditional TCC, namely the total contact leg section, with use of an open cell polyurethane foam to transfer load from the foot to the lower leg, thereby offloading the foot by suspending it within a padded fiberglass walking cast.

RESULTS

We did not observe statistically significant differences in mean peak plantar pressures in any plantar foot anatomic area or with any body mass between the two TCC designs.

CONCLUSION

Based on the results, we concluded that the alternate TCC design provides another viable TCC construct option for practitioners working with the neuropathic foot. This investigation also provides specific data on changes that occur in peak plantar pressures with use of the total contact cast and variable BMIs.

DECLARATION OF INTEREST

none.

Biofeedback can reduce foot pressure to a safe level and without causing new at-risk zones in patients with diabetes and peripheral neuropathy

BACKGROUND

Plantar pressure reduction is mandatory for diabetic foot ulcer healing. Our aim was to evaluate the impact of a new walking strategy learned by biofeedback on plantar pressure distribution under both feet in patients with diabetic peripheral neuropathy.

METHODS

Terminally augmented biofeedback has been used for foot off-loading training in 21 patients with diabetic peripheral sensory neuropathy. The biofeedback technique was based on a subjective estimation of performance and objective visual feedback following walking sequences. The patient was considered to have learned a new walking strategy as soon as the peak plantar pressure (PPP) under the previously defined at-risk zone was within a range of 40-80% of baseline PPP in 70% of the totality of steps and during three consecutive walking sequences. The PPP was measured by a portable in-shoe foot pressure measurement system (PEDAR(®)) at baseline (T0), directly after learning (T1) and at 10-day retention test (T2).

RESULTS

The PPP under at-risk zones decreased significantly at T1 (165 ± 9 kPa, p < 0.0001) and T2 (167 ± 11, p = 0.001), as compared with T0 (242 ± 12 kPa) without any increase of the PPP elsewhere. At the contralateral foot (not concerned by off-loading), the PPP was slightly higher under the lateral midfoot at T1 (68 ± 8 kPa, p = 0.01) and T2 (65 ± 8 kPa, p = 0.01), as compared with T0 (58 ± 6 kPa).

CONCLUSIONS

The foot off-loading by biofeedback leads to a safe and regular plantar pressure distribution without inducing any new 'at-risk' area under both feet.

A novel approach to mapping load transfer from the plantar surface of the foot to the walls of the total contact cast: a proof of concept study

BACKGROUND

Total contact casting is regarded as the gold standard treatment for plantar foot ulcers. Load transfer from the plantar surface of the foot to the walls of the total contact cast has previously been assessed indirectly. The aim of this proof of concept study was to determine the feasibility of a new method to directly measure the load between the cast wall and the lower leg interface using capacitance sensors.

METHODS

Plantar load was measured with pedar® sensor insoles and cast wall load with pliance® sensor strips as participants (n=2) walked along a 9 m walkway at 0.4±0.04 m/sec. The relative force (%) on the cast wall was calculated by dividing the mean cast wall force (N) per step by the mean plantar force (N) per step in the shoe-cast condition.

RESULTS

The combined average measured load per step upon the walls of the TCC equated to 23-34% of the average plantar load on the opposite foot. The highest areas of load on the lower leg were located at the posterior margin of the lateral malleolus and at the anterior ankle/extensor retinaculum.

CONCLUSIONS

These direct measurements of cast wall load are similar to previous indirect assessment of load transfer (30-36%) to the cast walls. This new methodology may provide a more comprehensive understanding of the mechanism of load transfer from the plantar surface of the foot to the cast walls of the total contact cast.

Vibrating perception threshold and body mass index are associated with abnormal foot plantar pressure in type 2 diabetes outpatients

AIMS

This study investigated the influencing factors of foot plantar pressure and attempted to find practical indicators to predict abnormal foot pressure in patients with type 2 diabetes mellitus (T2DM).

SUBJECTS AND METHODS

Vibration perception threshold (VPT) and foot plantar pressure in 1,126 T2DM outpatients were examined. Patients were assigned to Group A (n=599), Group B (n=312), and Group C (n=215) according to VPT values and to Group I (n=555), Group II (n=436), and Group III (n=135) based on body mass index (BMI). The clinical characteristics and pressure-time integral (PTI) were compared among the three groups, and the associated factors of the total PTI in the entire foot (T-PTI) were analyzed.

RESULTS

PTI of Group C in heel medial and heel lateral was significantly higher than that of Group A (all P<0.01). PTI of Group B in the right fifth metatarsal and heel medial was significantly higher than that of Group A (all P<0.05). T-PTI of Group C was significantly higher than those of Groups A and B, and that of Group B was higher than that of Group A (all P<0.01). PTI of Groups II and III in the second, third, and fourth metatarsal, midfoot, heel medial, and heel lateral was significantly higher than that of Group I (all P<0.05). T-PTI of Groups II and III was significantly higher than that of Group I (all P<0.01). Pearson correlation analysis showed that T-PTI was positively associated with age, VPT, waist circumference, waist-to-hip ratio, and BMI (P<0.05). In multiple stepwise regression analysis, VPT (P=0.004) and BMI (P=0.000) were independent risk factors of T-PTI, and each 1 unit increase in BMI increased the T-PTI by 5.962 kPa•s. Receiver operator characteristic curve analysis further revealed that the optimal cutpoint of VPT and BMI to predict the abnormal PTI was 21 V (odds ratio=2.33, 95% confidence interval 1.67-3.25) and 24.9 kg/m(2) (odds ratio=2.12, 95% confidence interval 1.55-2.90), respectively.

CONCLUSIONS

Having a VPT higher than 21 V and a BMI above 24.9 kg/m(2) increases the risk of excessive foot plantar pressure in Chinese T2DM.

Assessment and management of diabetic foot ulcers

Diabetic foot ulcers can cause considerable disability and morbidity. The complex pathology requires expert and in-depth assessment and management to achieve the best outcomes. Assessment is underpinned by attention to four key points: vascular sufficiency, neurological/sensory status, appropriateness of footwear, and presence of foot deformity. The 'shopping list' for management is derived from the assessment and requires careful planning and a multidisciplinary approach. This article outlines key first line principles and practices in assessment and management of diabetic foot ulcers, including the importance of offloading pressure and mechanical trauma to aid healing and prevent recurrence.

Off-loading the diabetic foot for ulcer prevention and healing

Retrospective and prospective studies have shown that elevated plantar pressure is a causative factor in the development of many plantar ulcers in diabetic patients and that ulceration is often a precursor of lower-extremity amputation. Herein, we review the evidence that relieving areas of elevated plantar pressure (off-loading) can prevent and heal plantar ulceration.There is no consensus in the literature concerning the role of off-loading through footwear in the primary or secondary prevention of ulcers. This is likely due to the diversity of intervention and control conditions tested, the lack of information about off-loading efficacy of the footwear used, and the absence of a target pressure threshold for off-loading. Uncomplicated plantar ulcers should heal in 6 to 8 weeks with adequate off-loading. Total-contact casts and other nonremovable devices are most effective because they eliminate the problem of nonadherence to recommendations for using a removable device. Conventional or standard therapeutic footwear is not effective in ulcer healing. Recent US and European surveys show that there is a large discrepancy between guidelines and clinical practice in off-loading diabetic foot ulcers. Many clinics continue to use methods that are known to be ineffective or that have not been proved to be effective while ignoring methods that have demonstrated efficacy.A variety of strategies are proposed to address this situation, notably the adoption and implementation of recently established international guidelines, which are evidence based and specific, by professional societies in the United States and Europe. Such an approach would improve the often poor current expectations for healing diabetic plantar ulcers.

Optimizing the offloading properties of the total contact cast for plantar foot ulceration

AIMS

Total contact casting is the gold standard offloading treatment for plantar foot ulceration, but the optimal technique and preferred materials are poorly defined and not readily prescribed in daily practice. We investigated in-cast pressure offloading in two types of total contact casts vs. a control condition, in patients with plantar foot ulceration.

METHODS

In-cast walking pressures were collected using the Novel Pedar-X system in 20 participants with a plantar foot ulcer in two types of total contact casts: a conventional total contact cast and a cushion-modified total contact cast incorporating an inlay of 6 mm slow-rebound cellular urethane and 6 mm soft cellular urethane. Casts were compared with a canvas cast shoe to establish baseline pressure values.

RESULTS

Compared with the cast shoe, the conventional total contact cast significantly reduced peak pressure at the ulcer site by 44%, mean pressure by 47% and pressure-time integral by 37% (P<0.001), while the cushion-modified total contact cast significantly reduced peak pressure at the ulcer site by 70%, mean pressure by 60% and pressure-time integral by 69% (P<0.001). Plantar pressure across the entire foot and each region of the foot was also reduced with the conventional total contact cast compared with the cast shoe, and further reduced by the cushion-modified total contact cast (P<0.05).

CONCLUSIONS

The offloading properties of the total contact cast can be enhanced with a 12 mm cellular urethane cushion modification. Further well-designed trials are required to understand and validate this cast technique and to demonstrate healing rates and safety in different patient populations.

Dressing plantar wounds with foam dressings, is it too much pressure?

Diabetes and its associated complications have become a major concern locally, nationally and internationally. One such complication is lower extremity amputation, commonly preceded by chronic ulceration. The cause of this tissue breakdown is multi-faceted, but includes an increase in pressure, particularly plantar pressure. As such, the choice of dressing to be applied to a plantar wound should ideally not increase this pressure further. A commonly used and possibly more bulky dressing is the foam dressing. This pilot study investigates the plantar pressures associated with three common foam dressings (Allevyn(®), Lyofoam(®) and Mepilex(®)) compared with a control dressing (Melolin(®)). Twelve healthy males and 19 females [SD] age 36.6 [10.4] were measured using the F-scan plantar pressure measurement system. Substantial variations in individual pressure changes occurred across the foot. No significant differences were identified, once a Bonferroni correction was applied. In healthy adults, it could be concluded that foam dressings do not have any effect on the plantar pressures of the foot. However, the need remains for a robust trial on a pathological population.

Heel skin stiffness effect on the hind foot biomechanics during heel strike

BACKGROUND

The human heel pad is a complex biological structure consisting of the fat pad and the skin. The mechanical properties of the skin layer are of significant importance to the load-bearing function of the heel pad and human locomotion. The condition of the heel skin is also directly associated with some medical conditions such as heel ulcers that may become a site for the skin breakdown, which is the most common precursor to lower extremity amputation among persons with diabetes. It is essential to develop a detailed understanding of the properties of the heel skin layer and its effect on hind foot biomechanics during heel strike.

OBJECTIVES

This work aims to gain a better insight into the biomechanical behaviour of the heel skin layer through a combined experimental and numerical study. The main objective is to characterise the biomechanical responses of the hind foot system during heel strike with potential variation of the skin stiffness based on a subject-specific finite element (FE) model and biomechanical testing.

METHODS

A three-dimensional (3D) FE model of the human hind foot incorporating a separate heel skin layer was developed based on subject-specific medical images. An inverse FE analysis of the in vivo indentation test was carried out to study the nonlinear material property of the heel skin. The FE model was then used to study the deformation of the hind foot during heel strike in comparison with the plantar pressure measurement results and to establish the effects of stiffness of the heel skin on the stress and pressure distributions.

RESULTS

The FE foot model with subject-specific heel skin properties was successfully used to predict the deformation of the hind foot during heel strike, and the results showed good agreements with biomechanical pressure measurements. The results showed that the high pressure and stress in the heel skin appeared in the centre region during a heel strike. Heel skin stiffness sensitivity studies showed that an increase in the skin stiffness had a limited effect on the stress and contact pressure of the hind foot bones, but caused a slight increase in the skin stresses, while skin softening caused a decrease in the peak plantar pressure and its distribution pattern changed. In addition, the results also suggest that skin softening may cause a higher stress level in the bones and ligaments.

CONCLUSION

The nonlinear parameter of the heel skin has been successfully predicted from in vivo indentation tests based on a subject-specific FE model. Skin properties' sensitivity tests clearly showed that the stiffness of the heel skin could have a direct effect on the biomechanics of the hind foot. The results suggest that individuals with a pathologically stiffened heel skin could exert an increase in the heel pressure, which may potentially lead to skin breakdown or ulcer.

Off-loading the diabetic foot for ulcer prevention and healing

BACKGROUND

Retrospective and prospective studies have shown that elevated plantar pressure is a causative factor in the development of many plantar ulcers in diabetic patients and that ulceration is often a precursor of lower extremity amputation. In this article, we review the evidence that relieving areas of elevated plantar pressure (off-loading) can prevent and heal plantar ulceration.

RESULTS

There is no consensus in the literature concerning the role of off-loading through footwear in primary or secondary prevention of ulcers. This is likely due to the wide diversity of intervention and control conditions tested, the lack of information about off-loading efficacy of the footwear used, and the absence of a target pressure threshold for off-loading. Uncomplicated plantar ulcers should heal in 6 to 8 weeks with adequate off-loading. The total contact cast and other nonremovable devices are most effective because they eliminate the problem of nonadherence to recommendations for using a removable device. Conventional or standard therapeutic footwear is not effective in ulcer healing. Recent United States and European surveys show a large discrepancy between guidelines and clinical practice in off-loading diabetic foot ulcers. Many clinics continue to use methods that are known to be ineffective or have not been proven effective, while ignoring methods that have been demonstrated to be efficacious.

CONCLUSIONS

A number of strategies are proposed to address this situation, notably the adoption and implementation of recently established international guidelines, which are evidence-based and specific, by professional societies in the United States and Europe. Such an approach would change the often poor current expectations for healing diabetic plantar ulcers.

Shoe inserts alter plantar loading and function in patients with midfoot arthritis

STUDY DESIGN

Experimental laboratory study supplemented by a case series.

OBJECTIVES

(1) To assess the effect of a 4-week intervention with a full-length insert on functional outcomes in patients with midfoot arthritis; (2) to examine the effect of the custom molded three-quarter-length (3Q) and full-length (FL) carbon graphite insert on plantar loading in patients with midfoot arthritis.

BACKGROUND

Given the coexistence of pain and lower-arched foot alignment in patients with midfoot arthritis, arch-restoring orthotic devices such as the 3Q insert are frequently recommended. However, patients continue to report foot pain despite using the 3Q insert. The FL insert has been proposed as an alternative, but objective data examining its efficacy are lacking.

METHODS

Twenty female patients with midfoot arthritis participated in the study. Functional outcomes were assessed using the Foot Function Index-Revised (FFI-R). Plantar loading during walking was measured in the following conditions: shoe only, shoe with 3Q insert, and shoe with FL insert. Repeated-measures analyses of variance with post hoc analyses were used for statistical analysis.

RESULTS

FL insert use for 4 weeks resulted in a 12% improvement in total FFI-R score (mean +/- SD before, 35.6 +/- 10.9; after, 31.1 +/- 9.8 [P = .03]). FL insert use resulted in a 20% reduction in medial midfoot average pressure loading (mean +/- SD, 64.8 +/- 20.4 and 51.0 +/- 15.4 kPa, with 3Q and FL insert respectively [P = .015]) and an 8.5% reduction in medial midfoot contact time (mean +/- SD, 84.9% +/- 6.4% and 76.4% +/- 7.1% of stance, with 3Q and FL insert respectively [P<.01]), compared to the 3Q insert. No differences in plantar loading were discerned between the shoe-only and FL conditions.

CONCLUSION

Symptomatic improvement in patients with midfoot arthritis treated with a FL insert was accompanied by reduced magnitude and duration of loading under the medial midfoot. These preliminary outcomes suggest that the FL insert may be a viable alternative in the conservative management of patients with midfoot arthritis.

LEVEL OF EVIDENCE

Therapy, level 4. J Orthop Sports Phys Ther 2009;39(7):522-531. doi:10.2519/jospt.2009.2900.

The efficacy of a removable vacuum-cushioned cast replacement system in reducing plantar forefoot pressures in diabetic patients

BACKGROUND

The purpose of this study was to determine the plantar forefoot offloading efficacy of a new prefabricated vacuum-cushioned cast replacement system designed for foot ulcer treatment in neuropathic diabetic patients.

METHODS

Fifteen diabetic subjects with peripheral neuropathy underwent in-shoe plantar pressure assessment while walking in five different footwear types: a standard vacuum-cushioned system with instantly moldable vacuum cushion and roller outsole, two modified vacuum-cushioned systems, one with flat surface vacuum cushion and one with flat outsole, a forefoot offloading shoe, and a control shoe. Regional peak pressures, pressure-time integrals, and inter-regional load transfers were calculated to determine the mechanical action of the footwear. Perceived walking comfort was tested using a 10-point visual analogue scale.

FINDINGS

Forefoot peak pressures and pressure-time integrals were significantly lower (by 41-56%) in the vacuum-cushioned system compared to control. Compared to the forefoot offloading shoe, the vacuum-cushioned system showed significantly higher metatarsal head peak pressures, similar metatarsal head pressure-time integrals, and significantly lower hallux peak pressures and pressure-time integrals. A major transfer of forefoot load to the midfoot explained the offloading efficacy of the vacuum-cushioned system. Few significant differences were present between the modified and standard vacuum-cushioned systems. Perceived walking comfort was significantly higher in the vacuum-cushioned system (score 6.6) than in the forefoot offloading shoe (score 3.4).

INTERPRETATION

The results showed that the vacuum-cushioned cast replacement system was effective in offloading the plantar forefoot of diabetic patients at risk for ulceration, although the contribution of the instantly moldable vacuum cushion and roller outsole were relatively small. The combined peak pressure, pressure-time integral and walking comfort results indicate that the vacuum-cushioned system may be a useful alternative for the forefoot offloading shoe in offloading the plantar diabetic forefoot.

Plantar pressure relief in the diabetic foot using forefoot offloading shoes

PURPOSE

Forefoot offloading shoes (FOS) are commonly used in clinical practice for treatment of plantar forefoot ulcers in the diabetic foot. The aim of this study was to assess the offloading efficacy of four different FOS models in comparison with a cast shoe and control shoe.

METHODS

In-shoe plantar pressures were measured during walking in each of the six footwear conditions in 24 neuropathic diabetic patients at high risk for plantar foot ulceration. For each of six foot regions, peak pressure, pressure-time integral, and force-time integral were calculated. Load transfer diagrams were developed to assess the footwear mechanisms of action. Perceived walking comfort was measured using a visual analogue scale (VAS). All comparisons between conditions were tested at P<0.05.

RESULTS

Peak pressures and pressure-time integrals at the metatarsal heads and hallux regions were significantly reduced (by 38-58%) in all FOS models when compared with the control shoe. The FOS also relieved metatarsal head peak pressure to a significantly larger extent than the cast shoe (approximately 20%). The load transfer diagrams showed a major transfer of approximately 40% of forefoot load to the midfoot explaining the offloading efficacy of the FOS. Perceived walking comfort was significantly lower in the FOS (VAS score 2.7-5.9) when compared with the control shoe (VAS 8.2) and cast shoe (VAS 6.8).

CONCLUSIONS

The data showed that all FOS models were effective in their primary goal, relieving forefoot pressure in at-risk neuropathic diabetic patients. Therefore, these shoes may be effective in offloading and healing plantar forefoot ulcers, although the low comfort scores should be considered as this may potentially affect adherence to treatment.

Footwear for the neuropathic patient: offloading and stability

Diabetic neuropathy is related to plantar ulceration through a variety of factors of which increased plantar pressures and loss of protective sensation are the most important. Loss of sensation in the lower limbs is also related to postural instability and an increased risk of falling. Ankle and foot proprioception play an important role in postural control and this sensory function is also affected by neuropathy. It is conceivable that footwear, orthotics, casts and braces used for treatment or prevention of plantar ulceration through offloading of the injured or at-risk foot area can exacerbate the postural instability and risk of falling. This has, however, received very limited attention in the literature. There are studies that have demonstrated that footwear adjustments can influence balance and stability in healthy, elderly subjects. The adjustments made to footwear for the diabetic foot are generally more dramatic and, therefore, are expected to have a greater influence on postural stability. Furthermore, casts and braces tend to deviate even more from normal footwear. This may seriously interfere with normal gait and posture and, therefore, stability. So far the evidence suggests that patients wearing such devices demonstrate markedly reduced activity levels. This reduced activity could add to the effect of offloading. This could also be interpreted to indicate problems with stability. This presentation will review the different types of offloading interventions frequently used for ulcer treatment and prevention and will consider the mechanical effect of these interventions on stability.

Diabetic foot ulcers — a comprehensive review

As the incidence of diabetes mellitus is increasing globally, complications related to this endocrine disorder are also mounting. Because of the large number of patients, foot ulcers developing in the feet of diabetics have become a public health problem. The predisposing factors include abnormal plantar pressure points, foot deformities, and minor trauma. Vulnerable feet usually already have vascular insufficiency and peripheral neuropathy. The complex nature of these ulcers deserves special care. The most useful prognostic feature for healing remains the ulcer depth, ulcers heal poorly if they clearly involve underlying tendons, ligament or joints and, particularly, when gangrenous tissue is seen. Local treatment of the ulcer consists of repeated debridement and dressing. No 'miraculous' outcome is expected, even with innovative agents like skin cover synthetics, growth factors and stem cells. Simple surgery like split skin grafting or minor toe amputations may be necessary. Sophisticated surgery like flap coverages are indicated for younger patients. The merits of an intact lower limb with an abnormal foot have to be weighed against amputation and prosthesis in the overall planning of limb salvage or sacrifice. If limb salvage is the decision, additional means like oxygen therapy, and other alternative medicines, might have benefits. The off-loading of footwear should always be a major consideration as a prevention of ulcer formation.

Plantar pressures are higher under callused regions of the foot in older people

BACKGROUND

Mechanically induced hyperkeratotic lesions (corns and calluses) are among the most common foot problems in older people. However, their aetiology is not well understood.

AIM

To compare the magnitude of pressures generated under the foot when walking in older people with and without plantar calluses.

METHODS

Peak plantar pressure measurements were obtained from 292 participants (99 men and 193 women) aged 62-96 years (mean +/- SD 77.6 +/- 6.9) recruited from a retirement village and a university health sciences clinic. Comparisons were then made between callused and noncallused regions of the foot.

RESULTS

In total, 151 participants (52%) had at least one plantar callus. Those with plantar calluses were more likely to be female, have moderate to severe hallux valgus, and at least one lesser toe deformity. Regional peak plantar pressures were significantly higher in people with calluses under the second metatarsophalangeal joint (2.34 +/- 0.46 vs. 2.12 +/- 0.51 kg/cm(2), P = 0.001), the third to fifth metatarsophalangeal joints (1.71 +/- 0.46 vs. 1.50 +/- 0.51 kg/cm(2), P = 0.009) and the hallux (1.40 +/- 0.34 vs. 1.23 +/- 0.47 kg/cm(2), P = 0.007) compared with people without calluses under these sites.

CONCLUSION

Plantar pressures are significantly higher under callused regions of the foot in older people. Raised pressure may play a role in the development of plantar calluses by accelerating the turnover rate of keratinocytes in the epidermis. Future studies should focus on evaluating the efficacy of pressure-relieving interventions in the prevention and treatment of keratotic disorders in older people.