Characterization of How a Walking Boot Affects Balance

Personalized Offloading Treatments for Healing Plantar Diabetic Foot Ulcers

BACKGROUND

Non-removable knee-high devices are the gold-standard offloading treatments to heal plantar diabetic foot ulcers (DFUs). These devices are underused in practice for a variety of reasons. Recommending these devices for all patients, regardless of their circumstances and preferences influencing their ability to tolerate the devices, does not seem a fruitful approach.

PURPOSE

The aim of this article is to explore the potential implications of a more personalized approach to offloading DFUs and suggest avenues for future research and development.

METHODS

Non-removable knee-high devices effectively heal plantar DFUs by reducing plantar pressure and shear at the DFU, reducing weight-bearing activity and enforcing high adherence. We propose that future offloading devices should be developed that aim to optimize these mechanisms according to each individual's needs. We suggest three different approaches may be developed to achieve such personalized offloading treatment. First, we suggest modular devices, where different mechanical features (rocker-bottom sole, knee-high cast walls/struts, etc.) can be added or removed from the device to accommodate different patients' needs and the evolving needs of the patient throughout the treatment period. Second, advanced manufacturing techniques and novel materials could be used to personalize the design of their devices, thereby improving common hindrances to their use, such as devices being heavy, bulky, and hot. Third, sensors could be used to provide real-time feedback to patients and clinicians on plantar pressures, shear, weight-bearing activity, and adherence.

CONCLUSIONS

By the use of these approaches, we could provide patients with personalized devices to optimize plantar tissue stress, thereby improving clinical outcomes.

Should weight-bearing activity be reduced during healing of plantar diabetic foot ulcers, even when using appropriate offloading devices?

Physical activity is an essential part of general health and diabetes management. However, recommending weight-bearing physical activity for people with plantar diabetic foot ulcers is controversial, even when gold standard offloading devices are used, as it is commonly thought to delay healing. We aimed to narratively review relevant studies investigating the relationship between plantar diabetic foot ulcer healing and weight-bearing activity, plantar pressure and device adherence. We defined relevant studies as those from two systematic reviews, along with those identified since using a similar updated Pubmed search strategy. We identified six studies. One study found that more daily steps were associated with worse ulcer healing, three found no significant association between steps and ulcer healing, and in two others the association was unclear. Thus, there is weak evidence for an inverse relationship between weight-bearing physical activity and plantar ulcer healing while utilizing offloading devices. We propose a Diabetic foot Offloading and Activity framework to guide future research to find the optimal balance between the positive and negative effects of weight-bearing activity in the context of foot ulcers. We hope such future studies will shed more conclusive light on the impact of weight-bearing activity on healing of plantar diabetic foot ulcers.

The role of vestibular cues in postural sway

Controlling posture requires continuous sensory feedback about body motion and orientation, including from the vestibular organs. Little is known about the role of tilt vs. translation vs. rotation vestibular cues. We examined whether intersubject differences in vestibular function were correlated with intersubject differences in postural control. Vestibular function was assayed using vestibular direction-recognition perceptual thresholds, which determine the smallest motion that can be reliably perceived by a subject seated on a motorized platform in the dark. In study A, we measured thresholds for lateral translation, vertical translation, yaw rotation, and head-centered roll tilts. In study B, we measured thresholds for roll, pitch, and left anterior-right posterior and right anterior-left posterior tilts. Center-of-pressure (CoP) sway was measured in sensory organization tests (study A) and Romberg tests (study B). We found a strong positive relationship between CoP sway and lateral translation thresholds but not CoP sway and other thresholds. This finding suggests that the vestibular encoding of lateral translation may contribute substantially to balance control. Since thresholds assay sensory noise, our results support the hypothesis that vestibular noise contributes to spontaneous postural sway. Specifically, we found that lateral translation thresholds explained more of the variation in postural sway in postural test conditions with altered proprioceptive cues (vs. a solid surface), consistent with postural sway being more dependent on vestibular noise when the vestibular contribution to balance is higher. These results have potential implications for vestibular implants, balance prostheses, and physical therapy exercises.NEW & NOTEWORTHY Vestibular feedback is important for postural control, but little is known about the role of tilt cues vs. translation cues vs. rotation cues. We studied healthy human subjects with no known vestibular pathology or symptoms. Our findings showed that vestibular encoding of lateral translation correlated with medial-lateral postural sway, consistent with lateral translation cues contributing to balance control. This adds support to the hypothesis that vestibular noise contributes to spontaneous postural sway.

Effect of Leg Length–Evening Device on Perceived Balance in Patients Wearing a Controlled Ankle Motion Boot

Background:

Patients are often made weightbearing as tolerated (WBAT) in a controlled ankle motion (CAM) boot for the management of various foot and ankle conditions. The CAM boot causes a leg length discrepancy (LLD) between the booted (longer) and contralateral (shorter) lower extremities. This discrepancy can potentially cause balance problems, undue strain on joints, and discomfort in patients. We hypothesized that a leg length–evening orthotic placed on the plantar aspect of the contralateral shoe improves balance among patients who are WBAT in a CAM boot.

Methods:

Patients made WBAT in a CAM boot were randomized to either the leg length–evening orthotic intervention group or to a control group in which patients wore a normal shoe of their choice. Patients were followed for 2 weeks and asked a series of questions pertaining to balance and pain experienced at their knees, hips, and back. Balance was the primary outcome and was scored from 0 (no difficulty with balance) to 10 (great difficulty with balance). Of 107 subjects enrolled and randomized, 95 (88.8%) completed the study, satisfying the a priori sample size requirement of 94 patients. There were no differences in baseline characteristics between groups (P > .05 for each).

Results:

Intervention patients reported less difficulty with balance than control patients (intention-to-treat analysis: 2.0±1.5 vs 3.2±1.8, P = .001; as-treated analysis: 2.1±1.7 vs 3.0±1.7, P = .009). Intervention and control patients did not differ with respect to pain experienced at their knees, hips, or back, or in a composite total pain score (P > .05 for each).

Conclusion:

This multicenter randomized controlled trial found that adding a limb length–evening orthotic to the plantar aspect of the contralateral shoe in a patient that is WBAT in a CAM boot improved patient-reported self-assessment of balance. The trial was powered to identify a difference in the primary outcome measure of balance and may have been insufficiently powered to identify differences in knee, hip, back, or total pain.

Level of Evidence:

Level II, prospective comparative study.

Associated Joint Pain With Controlled Ankle Movement Walker Boot Wear

Background:

Controlled ankle movement (CAM) walker boots may cause gait alterations and leg-length discrepancy. This study evaluates secondary site pain relating to immobilization in a CAM walker boot.

Methods:

Patients wearing a CAM walker boot were prospectively enrolled and evaluated for new or worsened secondary site pain. Surveys at four time points were completed to evaluate secondary site pain severity and its effect on function.

Results:

The study included 46 patients (mean age, 49 years). At transition out of the boot (mean, 4.2 weeks), 31 patients (67%) reported pain which was new or worse than at baseline. The sites most susceptible to pain were lower back, contralateral hip, and ipsilateral knee. Most pains (84%) began within the first 2 weeks of boot wear. Secondary site pain was less common after transition out of the boot: 18 patients (39%) at 1 month and 15 patients (33%) at 3 months.

Conclusion:

Secondary site pain after CAM walker boot wear is common. The frequency and severity of pain lessened after transition out of the boot. Yet, one-third of patients still had new or worsened secondary site pain 3 months after cessation of boot wear.

Decreasing an Offloading Device's Size and Offsetting Its Imposed Limb-Length Discrepancy Lead to Improved Comfort and Gait

OBJECTIVE

Patient adherence is a challenge in offloading diabetic foot ulcers (DFUs) with removable cast walkers (RCWs). The size and weight of an RCW, changes to gait, and imposed limb-length discrepancies may all discourage adherence. This study sought to determine whether RCW size and provision of a contralateral limb lift affected users' comfort and gait.

RESEARCH DESIGN AND METHODS

Twenty-five individuals at risk for DFUs completed several 20-m walking trials under five footwear conditions: bilateral standardized shoes, a knee-high RCW with shoe with or without an external shoe lift contralaterally, and an ankle-high RCW with shoe with or without an external shoe lift contralaterally. Perceived comfort ratings were assessed through the use of visual analog scales. Spatial and temporal parameters of gait were captured by an instrumented walkway, and plantar pressure was measured and recorded using pedobarographic insoles.

RESULTS

The bilateral shoes condition was reported to be most comfortable; both RCW conditions without the lift were significantly less comfortable (P < 0.01). In contrast to the ankle-high RCW, the knee-high RCW resulted in significantly slower walking (5.6%; P < 0.01) but greater offloading in multiple forefoot regions of the offloaded foot (6.8-8.1%; P < 0.01). Use of the contralateral shoe lift resulted in significantly less variability in walking velocity (52.8%; P < 0.01) and reduced stance time for the offloaded foot (2.6%; P = 0.01), but it also reduced offloading in multiple forefoot regions of the offloaded foot (3.7-6.0%; P < 0.01).

CONCLUSIONS

Improved comfort and gait were associated with the ankle-high RCW and contralateral limb lift. Providing this combination to patients with active DFUs may increase offloading adherence and subsequently improve healing.

Multivariate Analyses of Balance Test Performance, Vestibular Thresholds, and Age

We previously published vestibular perceptual thresholds and performance in the Modified Romberg Test of Standing Balance in 105 healthy humans ranging from ages 18 to 80 (1). Self-motion thresholds in the dark included roll tilt about an earth-horizontal axis at 0.2 and 1 Hz, yaw rotation about an earth-vertical axis at 1 Hz, y-translation (interaural/lateral) at 1 Hz, and z-translation (vertical) at 1 Hz. In this study, we focus on multiple variable analyses not reported in the earlier study. Specifically, we investigate correlations (1) among the five thresholds measured and (2) between thresholds, age, and the chance of failing condition 4 of the balance test, which increases vestibular reliance by having subjects stand on foam with eyes closed. We found moderate correlations (0.30–0.51) between vestibular thresholds for different motions, both before and after using our published aging regression to remove age effects. We found that lower or higher thresholds across all threshold measures are an individual trait that account for about 60% of the variation in the population. This can be further distributed into two components with about 20% of the variation explained by aging and 40% of variation explained by a single principal component that includes similar contributions from all threshold measures. When only roll tilt 0.2 Hz thresholds and age were analyzed together, we found that the chance of failing condition 4 depends significantly on both (p = 0.006 and p = 0.013, respectively). An analysis incorporating more variables found that the chance of failing condition 4 depended significantly only on roll tilt 0.2 Hz thresholds (p = 0.046) and not age (p = 0.10), sex nor any of the other four threshold measures, suggesting that some of the age effect might be captured by the fact that vestibular thresholds increase with age. For example, at 60 years of age, the chance of failing is roughly 5% for the lowest roll tilt thresholds in our population, but this increases to 80% for the highest roll tilt thresholds. These findings demonstrate the importance of roll tilt vestibular cues for balance, even in individuals reporting no vestibular symptoms and with no evidence of vestibular dysfunction.

Preliminary Evaluation of a Cycling Cleat Designed for Diabetic Foot Ulcers

BACKGROUND

Offloading devices for diabetic foot ulcers (DFU) generally restrict exercise. In addition to traditional health benefits, exercise could benefit DFU by increasing blood flow and acting as thermotherapy. This study functionally evaluated a cycling cleat designed for forefoot DFU.

METHODS

Fifteen individuals at risk of developing a DFU used a recumbent stationary bicycle to complete one 5-minute cycling bout with the DFU cleat on their study foot and one 5-minute bout without it. Foot stress was evaluated by plantar pressure insoles during cycling. Laser Doppler perfusion monitored blood flow to the hallux. Infrared photographs measured foot temperature before and after each cycling bout.

RESULTS

The specialized cleat significantly reduced forefoot plantar pressure (9.9 kPa versus 62.6 kPa, P < .05) and pressure time integral (15.4 versus 76.4 kPa*sec, P < .05). Irrespective of footwear condition, perfusion to the hallux increased (3.97 ± 1.2 versus 6.9 ± 1.4 tissue perfusion units, P < .05) after exercise. Infrared images revealed no changes in foot temperature.

CONCLUSIONS

The specialized cleat allowed participants to exercise with minimal forefoot stress. The observed increase in perfusion suggests that healing might improve if patients with active DFU were to use the cleat. Potential thermotherapy for DFU was not supported by this study. Evaluation of the device among individuals with active DFU is now warranted.

Psychological and Biomechanical Aspects of Patient Adaptation to Diabetic Neuropathy and Foot Ulceration

PURPOSE OF REVIEW

The purpose of this review was to elucidate how psychological and biomechanical factors interrelate in shaping patients' experience with diabetic symmetric polyneuropathy (DSPN) and its sequela-diabetic foot ulceration (DFU).

RECENT FINDINGS

Recent findings emphasize the importance not only of neuropathic pain but also of other DSPN symptoms, such as unsteadiness. We highlight the negative spiral between unsteadiness, falls, and psychological distress. Moreover, unsteadiness is a key determinant of non-adherence to offloading resulting in the delayed DFU healing. While depression is an established predictor of incident DFU, findings linking depression and DFU healing remain inconclusive. Examination of physical activity in DFU development and healing represents the most recent application of research to this field. Research evidence indicates that DSPN markedly impairs physical and emotional functioning and suggests that there is an unmet need for the development of multifaceted interventions that address both psychological distress and biomechanical challenges experienced by patients with this debilitating complication of diabetes.

Monitoring Location-Specific Physical Activity via Integration of Accelerometry and Geotechnology Within Patients With or At Risk of Diabetic Foot Ulcers: A Technological Report

OBJECTIVE

Physical activity variability is a risk factor for diabetic foot ulcers (DFU). Geographic context may influence variability. This study developed initial methods for monitoring location-specific physical activity in this population. Secondarily, preliminary comparisons in location-specific physical activity were made between patients at risk versus patients with active DFU.

METHODS

Five at-risk and 5 actively ulcerated patients were monitored continuously for 72 hours with physical activity and GPS monitors. A custom algorithm time synchronized the 2 devices' data.

RESULTS

On average for all 10 subjects, 1.5 ± 2.1% of activity lacked a corresponding GPS location. 80 ± 11% of self-reported activity events per subject had a GPS identified location. The GPS identified locations were in agreement with the self-reported locations 98 ± 6% of the time. DFU participants' weight-bearing activity was 188% higher at home than away from home. At-risk participants showed similar weight-bearing activity at home as active DFU participants, however, at-risk participants had 132% more weight-bearing activity away-from-home.

CONCLUSIONS

Objectively monitoring location-specific physical activity proved feasible. Future studies using such methodology may enhance understanding of pathomechanics and treatment of DFU.

Physiological and psychological challenges of increasing physical activity and exercise in patients at risk of diabetic foot ulcers: a critical review

Obesity and a sedentary lifestyle are common challenges among individuals at risk of diabetic foot ulcers. While substantial research exists on physical activity interventions in adults with diabetes, those at greatest risk for foot ulceration were often excluded or not well represented. Both at-risk patients and their clinicians may be hesitant to increase physical activity because of their perception of diabetic foot ulcer risks. Physical activity is not contraindicated for those at risk of diabetic foot ulcer, yet patients at risk present with unique barriers to initiating increases in physical activity. This review focuses upon the physiological and psychological challenges of increasing physical activity and exercise in patients at risk of diabetic foot ulcers. Offloading, diabetic peripheral neuropathy, depression, pain, self-efficacy and social support, diabetic foot ulcer risk-specific beliefs and emotions, and research to date on exercise interventions in this population are all discussed. Additionally, recommendations for implementing and researching physical activity interventions for individuals at risk for diabetic foot ulcer are provided. Copyright © 2016 John Wiley & Sons, Ltd.

Role and Determinants of Adherence to Off-loading in Diabetic Foot Ulcer Healing: A Prospective Investigation

OBJECTIVE

Studies indicate that off-loading adherence is low in patients with diabetic foot ulcers (DFUs), which may subsequently delay healing. However, there is little empirical evidence for this relationship or the factors that influence adherence.

RESEARCH DESIGN AND METHODS

This prospective, multicenter, international study of 79 (46 from the U.K. and 33 the U.S.) persons with type 2 diabetes and plantar DFUs assessed the association between off-loading adherence and DFU healing over a 6-week period. Additionally, potential demographic, disease, and psychological determinants of adherence were examined. DFUs were off-loaded with a removable device (77% a removable cast walker). Off-loading adherence was assessed objectively by activity monitors. Patient-reported measures included Hospital Anxiety and Depression Scale (HADS), Neuropathy and Foot Ulcer Quality of Life (NeuroQoL) instrument, and Revised Illness Perception Questionnaire (IPQ-R).

RESULTS

Off-loading adherence was monitored for 35 ± 10 days, and devices were used during 59 ± 22% of subjects' activity. In multivariate analyses, smaller baseline DFU size, U.K. study site, and better off-loading adherence predicted smaller DFU size at 6 weeks (P < 0.05). Better off-loading adherence was, in turn, predicted by larger and more severe baseline DFUs, more severe neuropathy, and NeuroQoL foot pain (P < 0.05). In contrast, greater NeuroQoL postural instability predicted worse off-loading adherence (P < 0.001). HADS and IPQ-R measures were not significantly associated with off-loading adherence.

CONCLUSIONS

Off-loading adherence is associated with the amount of DFU healing that occurs, while postural instability is a powerful predictor of nonadherence. Clinicians should take this neuropathic symptom into consideration when selecting an off-loading device, as off-loading-induced postural instability may further contribute to nonadherence.