The efficacy of a removable vacuum-cushioned cast replacement system in reducing plantar forefoot pressures in diabetic patients
Introduction
Foot ulcers are a significant burden in patients with diabetes mellitus. These ulcers may lead to infection and eventually amputation if not adequately treated (Boulton et al., 2004). Excessive mechanical pressure on the foot causing trauma which is not recognized by the patient due to loss of protective sensation is a major risk factor for the development of foot ulcers, in particular on the plantar surface (Veves et al., 1992). Reducing these excessive pressures (named ‘offloading’) is the most important component of treatment of these neuropathic plantar foot ulcers. Different devices are used for this purpose in clinical practice. The total contact cast (TCC) is the best described offloading modality and has proven to be highly effective in reducing plantar foot pressures (Baumhauer et al., 1997, Beuker et al., 2005, Lavery et al., 1996) and in healing neuropathic plantar foot ulcers (Armstrong et al., 2001). However, the use of the TCC requires trained casting personnel and sufficient time for application and re-application of the cast. Furthermore, complications may occur with the use of the TCC and patient acceptance is not always high. For these reasons, the use of the TCC for ulcer treatment is limited in many centers as data from a recent US survey shows (Wu et al., 2008).
As alternatives for casting, prefabricated devices are commonly used in clinical practice. These devices include below-the-knee systems such as removable walking braces and ankle-high devices such as half shoes and forefoot offloading shoes. All these devices have been shown to be effective in reducing plantar foot pressures (Beuker et al., 2005, Bus et al., 2009, Fleischli et al., 1997, Lavery et al., 1996), and many have also been shown to be effective in healing plantar diabetic foot ulcers (Armstrong et al., 2005, Chantelau et al., 1993, Katz et al., 2005). The data from these studies also show that ankle-high devices do not reduce pressure to the same level as below-the-knee devices but have the advantage that they are lighter in weight and do not immobilize the ankle joint, which facilitates walking, prevents muscle atrophy with long term use, and improves patient acceptance.
A new prefabricated ankle-high vacuum-cushioned cast replacement system (VCRS) has been designed for treatment of plantar forefoot ulcers in diabetic patients. This system comprises a vacuum cushion (bean bag) in conjunction with a roller walking sole. The vacuum cushion can be remodeled instantly to accommodate for structural abnormalities or changes in the shape of the patients’ foot. Furthermore, the system features a lightweight stable lattice frame structure in which the foot and lower leg are placed to provide stability. The VCRS is a removable device which can be reapplied instantly for wound control purposes and it requires only limited instruction to apply. Currently, no scientific evidence exists for the efficacy of the VCRS in reducing pressures underneath the forefoot in diabetic patients. Therefore, the purpose of this study was to assess the plantar forefoot offloading efficacy of the VCRS in neuropathic diabetic patients at risk for plantar ulceration and compare this with a forefoot offloading shoe (FOS) and a control shoe condition. Furthermore, we aimed to assess the specific contribution of the instantly moldable vacuum cushion and the roller outsole of the VCRS in offloading the forefoot as well as perceived walking comfort using this system. We hypothesized that the VCRS would be more effective than the control shoe and similarly effective as the FOS in reducing plantar forefoot pressures in diabetic patients. Furthermore, we anticipated a significant contribution of the custom molded vacuum cushion and roller outsole in the forefoot offloading effect of the VCRS together with a higher walking comfort in the VCRS than in the FOS.
Section snippets
Study design
This study was conducted using a repeated measures study design in which five different footwear conditions were tested in each patient during one single test session.
Subjects
Fifteen diabetic patients at high risk for developing plantar foot ulcers were recruited from our outpatient diabetic foot clinic and participated in this study. All patients had loss of protective sensation due to peripheral neuropathy as confirmed by the inability to sense a 10 g monofilament on the plantar hallux, first
Results
Walking speed varied marginally between footwear conditions and no significant differences were present. The results for walking speed, peak pressure, pressure–time integral, and perceived walking comfort are summarized in Table 2.
Peak pressures were significantly lower in both VCRS and FOS conditions when compared with the control shoe in each of the six foot regions, except the midfoot, with the largest pressure reductions found at the metatarsal heads: 45–59%. At the midfoot, peak pressure
Discussion
The results of the study show that the VCRS was effective in relieving forefoot pressures in the neuropathic diabetic patients tested. Between 41% and 56% relief in peak pressure and pressure–time integral were found when compared with the control shoe condition. The VCRS was less effective than the FOS in reducing peak pressure at the metatarsal heads, but more effective in relieving the hallux region. Furthermore, the results showed that the offloading contribution of the instant custom
Conclusions
This study was performed to assess the offloading efficacy, mechanisms of offloading and the perceived walking comfort of a new prefabricated vacuum-cushioned cast replacement system in diabetic patients at risk for plantar foot ulceration. The use of the VCRS resulted in a substantial pressure relief in the forefoot when compared to a control shoe condition. In comparison with a FOS, the VCRS was less effective in relieving peak pressures at the metatarsal heads, similarly effective in
Conflict of Interest
The authors declare that there is no conflict of interest.
Acknowledgements
The authors gratefully acknowledge the help of Tessa Busch, physiatrist, in recruiting patients for this study. The study was sponsored by OPED GmbH (Valley, Germany) who provided an unrestricted research grant to conduct the study. The sponsor did not have any involvement in the setup, data collection, analysis or interpretation of the study, the writing of the manuscript, or the decision to submit the manuscript for publication.
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The effect of induced joint restriction on plantar pressure during gait – a pilot study
2021, Gait and PostureCitation Excerpt :Total contact casts and removable walkers have been reported to be the most effective offloading options in the presence of ulceration, showing that they successfully redistribute and reduce excessive plantar loads by transferring the load to the devices themselves, and also by modifying the biomechanics of the roll-over process [7]. Other treatment options which do not entail constraints to ankle joint movement, such as forefoot offloading footwear or total-contact orthoses, are somewhat less effective when used on their own both in ulcer healing and prevention [8,9]; thus it seems that the underlying pathomechanism of plantar pressure should be investigated by also addressing joint kinematics and kinetics. To date, several authors have reported significantly altered joint kinematics, joint kinetics and plantar pressures during gait in individuals who are at high risk of developing diabetic foot ulceration [10–13].
The value of reporting pressure-time integral data in addition to peak pressure data in studies on the diabetic foot: A systematic review
2013, Clinical BiomechanicsCitation Excerpt :If walking speed would have been standardized, differences would have probably been absent or minimal in these studies. Third, explanations for the differences found between results from both pressure parameters were not provided or not meaningful in four studies (Bacarin et al., 2009; Bus et al., 2009a, 2009b; Rao et al., 2010). For example, the footwear studies by Bus et al. showed that contact time may play a role in explaining differences between the data from both parameters.
A novel approach to mechanical foot stimulation during human locomotion under body weight support
2011, Human Movement ScienceCitation Excerpt :The tactile pressure input from the soles is attenuated and may vary significantly with body unloading (Flynn, Canavan, Chiang, & Cavanagh, 1997; Ivanenko et al., 2002) or when using gait machines enabling the repetitive foot motion (Dietz & Colombo, 2004; Hesse, Schmidt, & Werner, 2006). Several techniques have been previously proposed to increase or modify an input from the foot (Hijmans, Geertzen, Schokker, & Postema, 2007; Priplata, Niemi, Harry, Lipsitz, & Collins, 2003) such as step-synchronized vibration stimulation of soles (Novak & Novak, 2006; Priplata et al., 2006), ankle–foot orthosis (Gordon, Wu, Kahn, Dhaher, & Schmit, 2009), redistributing plantar pressure footwear (Bus, Waaijman, Arts, & Manning, 2009; Duranti, Galletti, & Pantaleo, 1985; Rao, Baumhauer, Becica, & Nawoczenski, 2009), mechanical support stimulation imitating walking in conditions of microgravity or prolonged hypokinesia (Chernikova, Umarova, Saenko, & Kozlovskaya, 2007; Sayenko, Miller, Ivanov, Galanov, & Guekht, 2005) or electrical stimulation of distal nerves. The latter approach has been typically used to test cutaneous reflexes rather than to imitate or restore the sensory input from the foot.
Off-loading the diabetic foot for ulcer prevention and healing
2010, Journal of Vascular SurgeryCitation Excerpt :For these reasons, devices that only extend to the ankle, such as cast shoes and forefoot off-loading shoes, may be less effective in off-loading the foot than devices that extend above the ankle, as do TCCs and walkers. Reported off-loading values for such devices range from 44% to 64% compared with control.18,19,21,22 Various therapeutic footwear designs can effectively off-load at-risk foot regions.
Effectiveness of offloading interventions for people with diabetes-related foot ulcers: A systematic review and meta-analysis
2024, Diabetes/Metabolism Research and ReviewsOffloading treatment for diabetes‑related foot ulcer: introduction to 9th International Symposium on the Diabetic Foot and interpretation of the latest guideline
2023, Chinese Journal of Diabetes Mellitus