Effectiveness of Off-Loading Devices in Patients With Active Diabetic Foot Ulcer: A Systematic Review

Abstract

A systematic review of the effectiveness of off-loading in the diabetic foot was done. Searches were conducted in October 2022 using the PubMed and Scielo databases. Randomized clinical trials or controlled clinical trials were included. Two authors performed the study selection and data extraction, and any discrepancies between the 2 reviewers were resolved through discussion with a third reviewer. Fourteen papers met the selection criteria with 822 patients included, but the sample sizes in all studies were small. Most of the published studies were done in European countries. Total contact cast was the most effective off-loading. The present review studies the effectiveness of off-loading systems in patients with diabetic foot ulcer, as well as different off-loading methods, with total contact cast proving to be the gold standard, despite its adverse effects.

Keywords

diabetic foot (DF)diabetic foot ulcer (DFU) off-loading

Introduction

According to the World Health Organization, diabetes mellitus (DM) is a chronic disease that occurs when the pancreas does not secrete enough insulin or when the body does not effectively use the insulin it produces.¹

One of the complications of DM is Diabetic Foot Syndrome. Diabetic Foot Syndrome is defined as ulceration, infection, and deep tissue destruction associated with diabetic neuropathy and peripheral arterial disease (PAD) in the lower extremities.²

Diabetic foot ulcer (DFU) is a complication with high incidence. These ulcers are associated with severe morbidity and a great reduction in patients’ quality of life. It is very common to find osteomyelitis in these lesions, an infection of the bone that requires early treatment to avoid its spread and negative consequences.^3,4

The prevalence of foot ulcers in the DM population is 4% to 10%. The lifetime risk of developing this complication is estimated to be 15%. The risk of foot ulceration and lower limb amputation increases with the patient's age and duration of DM.⁴ The many risk factors and interactions between other conditions such as obesity, psychosocial factors, activity, and treatment compliance make it very difficult to control and assess the situation, thus, making it hard to reproduce the different kinds of therapies and results shown in the literature.⁵ The failure to decrease the number of amputations may be partially attributed to poor understanding of direct wound care, off-loading, and choice of the appropriate treatment modality.⁶

The mainstays of current DFU management include local wound care through debridement, dressings, off-loading, vascular assessment, treatment of active infection, and glycemic control.⁷

For good and rapid healing of DFU, the absence or relief of pressure is vital. For this reason, different types of off-loading systems depend on the case to be treated. Some off-loading devices are postsurgical shoes with rigid soles, boots, orthopedic walkers, and felts. The total contact cast (TCC) is considered the gold standard device, although it is not indicated in patients with PAD or infection.^7,8 The authors consider that off-loading methods promote the healing of DFU. It should be emphasized that pharmacological treatment alone cannot lead to the successful treatment of DFUs without adequate off-loading. Inadequate off-loading is one of the most frequent reasons for delayed wound healing.⁹ Therefore, the main aim of the review is to evaluate the effectiveness of off-loading in patients with active DFU.

Methods

Study Design

A systematic review of the effectiveness of off-loading in DFU was carried out using a checklist of The Preferred Reporting Items for Systematic Reviews and Meta-Analyses.¹⁰

Literature Search

Searches were conducted in October 2022. For this systematic review, several bibliographic searches were carried out in the PubMed and Scielo databases. The following search terms were used in the PubMed database: “Diabetic foot ulcer” and “off-loading.” And another search is carried out in the Scielo database, using “Diabetic foot ulcer” and “off-loading” as search criteria. In both cases, AND was used as the Boolean operator. Vancouver style, citing in order of appearance in the bibliography section.

Article Selection Criteria

Inclusion criteria were as follows: published articles were selected that demonstrated research on diabetic foot off-loading systems regardless of the year of publication, but up to complete healing of the lesion and the effectiveness of different off-loading systems and their types. In addition, the focus was on inclusion in controlled clinical trials and randomized controlled clinical trials. All the studies that have been chosen are conducted in humans with DM. The languages selected for the articles are Spanish and English.

Exclusion criteria were as follows: case reports, meta-analyses, letters, editorials, and articles that did not show interest in off-loadings and their effectiveness were excluded. References from systematic reviews and meta-analyses were also examined to identify additional articles. In addition, articles dealing with off-loading through surgeries were excluded.

The search and selection of articles were performed by 2 independent raters (SV-R-R and AT-G). Any discrepancies between the raters were resolved through discussion with a third reviewer (JLL-M).

Results

Search Results

In the initial search, with the search descriptors and the Boolean operator AND, 658 articles were acquired, of which, after applying the inclusion and exclusion criteria, 564 articles were discarded, leaving 94 records to examine. After an assessment of the title and abstract, 76 articles were excluded, leaving 18 full-text articles assessed for eligibility. Four full-text articles were excluded due to protocol criteria or insufficient data. Ultimately, 14 articles were used to produce the results of this systematic review (Figure 1).

Figure 1.

Flowchart of the identified studies.

Characteristics of the Included Studies

The data extracted from the 14 articles in the systematic review are summarized in Table 1. A total of 822 patients were included in the total number of articles.

Table 1.

Summary of Studies Included in the Systematic Review.

Author	Study design	Study site	Number of participants	Comparative group	Method of off-loading	Type of ulcer	Mesure of off-loading effectiveness	Effective/not effective	Complications of off-loading
Potier et al¹²	RCT, open-label, multicenter.	France	112 patients	Standard or customized removable discharge device	Orthodiab	Neuropathic DFU	Higher healing rate was observed with conventional device	Noneffective	Low adherence
Bus et al¹⁵	RCT, multicenter, blinded	The Netherlands and Germany	60 patients	Ankle-high custom-made shoe or prefabricated ankle-high shoe FOS	TCC bivalve	Plantar forefoot neuropathic DFU	Statistical analysis was performed (the result was not significant between treatments)	-	Pressure points and abrasions
Najafi et al¹³	CT	United States	49 patients	iTCC	Removable plaster walker	Plantar neuropathic DFU	Measurement of adherence to off-loading by PAMshirt	Effective	Muscle weakness and atrophy. Loss of mobility. Poor adherence
Lavery et al²⁰	Single-blind RCT	United States	73 patients	HS and SRB	TCC	Grade 1A and 2A forefoot UPD in Texas	Through a patient satisfaction survey	Effective	Secondary wounds, infections, iatrogenic wounds, and bad acceptance
Miyan et al²¹	RCT	Pakistan	70 patients	Modified plaster of Paris with plywood platform and Scotchcast boot	Modified footwear (sandal)	Plantar UPD of the foot, stages 1A and 2A in Texas	The modified footwear group was found to be the most profitable	Effective	Device rupture and mild maceration
Gutekunst et al¹⁶	RCT	United States	23 patients	Removable plaster boot	TCC	Plantar neuropathic DFU, Wagner grade 1 or 2	Analysis of covariance to compare loading patterns. Healed a higher percentage with TCC	Effective	-
Faglia et al²²	RCT	Italy	45 patients	TCC	RCW	Neuropathic, noninfected, nonischemic plantar DFU	There was not much difference in healing time with the different treatments	-	Partial rupture of the stapes, catching, bad odor, and maceration of the perilesional skin
Van De Weg et al¹⁹	CT	The Netherlands	43 patients	CTF	TCC	Neuropathic DFU, Wagner grade 1 or 2	Shorter healing time in plaster cast patients	Effective	Costly, discomfort, postural instability, abrasions, and local complications associated with the device
Caravaggi et al²³	RCT	Italy	60 patients	Fiberglass discharge plaster	Aircast pneumatic off-loading device	Plantar neuropathic DFU	The healing time of the glass fiber off-loading plaster group was shorter	Effective	Infection of ulcer, new plaster ulcer
Piaggesi et al¹⁸	RCT	Italy	40 patients	Optima Diab walking frame	TCC	Plantar neuropathic DFU, superficial and noninfectious	By means of a patient satisfaction survey	Effective	Maceration in the perilesional area with TCC
Katz et al¹⁷	RCT	United States	41 patients	TCC	iTCC^a	Nonischemic, neuropathic plantar DFU	iTCC can be as effective as TCC on superficial lesions	-	Local maceration, broken plaster, second ulcer, abrasions, and edema
Armstrong et al¹⁴	RCT	Estados Unidos	50 patients	RCW	iTCC^a	DFU neuropathic, grade 1A Texas	Patients treated with iTCC healed earlier than those treated with TCC	Effective	Low adherence to the device
Ha Van et al²⁴	Non-RCT	France	93 patients	Off-loading shoes	Nonremovable fiberglass plaster cast boot	Nonischemic, noninfected, plantar DFUs	By means of a questionnaire	Effective	Cellulitis and osteomyelitis, secondary ulcers, distal edema, and pressure ulcers.
Armstrong et al¹¹	RCT	United States	63 patients	Half shoe or RCW	TCC	Nonischemic and noninfected superficial plantar DFU	TCC heals more wounds in a shorter period	Effective	Discomfort, instability, and poor grip

Abbreviations: RCT, randomized controlled trial; DFU, diabetic foot ulcer; FOS, forefoot-offloading shoe; TCC, total contact cast; CT, controlled trial; HS, healing sandal; SRB, shear-reducing footbed; CTF, custom-made temporary footwear; iTCC, “instant” total contact cast; RCW, removable cast walker; non-RCT, nonrandomized controlled trial.

iTCC is an RCW that is made nonremovable by wrapping it circumferentially with a single strip of glass fiber casting material.

Most of the publications have been developed in European countries, but several have been carried out in the United States, one of them in Pakistan. The sample sizes were generally not very large, with only one article exceeding 100 subjects.

The first clinical trial of off-loading devices for the management of UPD was published in 2001 by Armstrong et al.¹¹ The last published article is from 2 years ago (2020) by Potier et al,¹² which shows that, despite being a fundamental pillar for the management of UPD, it is not a topic of concern among scientific publications, with only 14 RCTs in the last 22 years.

Concerning the off-loading device used in the studies, TCC is the most used. In addition, the most common method used to assess treatment efficacy was healing time, where shorter times are more effective for off-loading. Most of the articles showed off-loading devices that were found to be effective.

Finally, among the complications, we can observe that the most frequent are muscle weakness and atrophy, secondary to immobilization. However, the patient's poor adherence to these devices also stands out.

Discussion

After reviewing 14 articles, we can state that off-loading efficacy is crucial for managing DFU, but the ideal off-loading must be chosen in each case. Najafi et al¹³ and Armstrong et al¹⁴ agree that patients are less active when treated with irremovable casts than with removable shoes or casts. Irremovable casts are considered the gold standard off-loading treatment for DFU.¹³ Similarly, removable off-loading is the common standard of care for treating DFU.¹² The present study¹⁵ suggests a higher prevalence of healing in patients treated with TCC. This irremovable cast does not indicate ulcers with soft tissue infection or osteomyelitis.¹¹

In addition, Gutekunst et al¹⁶ also show that to improve healing, it is advisable to use immovable devices such as the TCC or a cast walker boot that has become immovable.

Likewise, Najafi et al¹³ and Armstrong et al¹⁴ seem to agree that there are significant differences in activity behavior between patients off-loaded with a removable cast walker (RCW) and those off-loaded with the same device but nonremovable (iTCC), concluding that patients treated with iTCC healed earlier than those treated with RCW.

However, Katz et al¹⁷ suggest that iTCC may be as effective as standard TCC and may also be associated with fewer complications, less time to implement, and therefore, lower cost.

Potier et al¹² studied the Orthèse diabète, a removable off-loading that immobilizes the foot and ankle joints but did not show any superiority over the standard removable off-loading for the healing of neuropathic DFU. Therefore, this method does not seem very effective for this type of ulcer. In addition, more adverse events were detected with this method compared to the conventional approach. However, Piaggesi et al affirm the efficacy and safety of the Optima Diab immovable walker, which is more practical, less expensive, and more accepted by patients than the TCC.¹⁸

Bus et al¹⁵ conducted the first single-blind multicenter RCT to compare 3 removable off-loading devices for the healing of neuropathic DFU; no significant differences in healing efficacy were observed between these 3 devices. Likewise, Van De Weg et al¹⁹ show the first RCT comparing off-loading using a standard TCC with a custom-made shoe.

Similarly, Lavery et al²⁰ evaluated the efficacy of 3 off-loading techniques for healing DFU: TCC, a healing sandal, and a removable boot with a shear-reducing insole (SRB). The authors concluded that patients treated with TCC had the highest proportion of healed wounds and the fastest healing time. However, the SRB had the lowest healing and the highest attrition rate during the study. A patient satisfaction survey is conducted.

On the other hand, in Pakistan, Miyan et al²¹ evaluated the efficacy of locally applied pressure relief techniques on plantar foot ulceration in people with DM. The modified footwear group was the most cost-effective among the 3 techniques. Faglia et al described another type of off-loading called Stabil-D; this walker promotes healing due to its rigid capacity and good pressure distribution. Therefore, it is a good off-loading option for patients who do not tolerate TCC.²²

Caravaggi et al²³ compare an Air cast pneumatic off-loading device and a fiberglass off-loading plaster. It was concluded that the healing time with the fiberglass off-loading plaster is shorter. Ha Van et al also claim that the nonremovable fiberglass plaster boot effectively reduced the risk of osteomyelitis and healing DFU, as it enforced compliance with off-loading.²⁴

Nowadays, although the use of TCC is considered the gold standard of off-loading for DFUs, it should be noted that the recommendation is aimed at patients with neuropathic ulcers. In contrast, the use of TCC is limited in patients with neuroischemic ulcers and contraindicated in patients with infection and/or critical ischemia. In addition, the presence of ischemia complicates the management of DFUs with no direct benefit being obtained by off-loading, and revascularization being necessary for the correct management of the patient and to obtain ulcer healing.²²

Importance of the Study

In short, based on the scientific evidence found for this review, early treatment of DFU should be considered of great importance. Also, off-loading is vital to reduce the pressure and friction on the ulcer and thus help to heal more quickly. Also, whenever an off-loading is administered, it is advisable to explain to the patient the importance of compliance with the treatment, as well as not walking excessively to avoid complications. Poor adherence to the device, weakness, muscle atrophy, and postural instability is common adverse effects.

Weaknesses and Strengths of the Study

This is the only systematic review of controlled clinical trials addressing the different types of off-loading in DFU. The available evidence is insufficient to decide how to treat an ulcer in a patient with DM, as each patient and each ulcer is different and requires individualized treatment. Therefore, more studies comparing different types of off-loading are needed.

In addition, most studies are not blinded, as there is no possibility of blinding the discharge to the patient and the investigator, which may influence the analysis of efficacy, and there is a risk of bias.

One of the strengths of our study is to compare the different off-loading methods, analyzing their adverse effects, ulcer etiology, and off-loading effectiveness in each study, ultimately identifying the most effective method.

Unanswered Questions and Future Research

There are few studies comparing the methods of off-loading currently in use, and there is a lack of scientific evidence to recommend their use. Therefore, RCTs with a blinded evaluator comparing different off-loading devices for managing DFU are needed to help understand the advantages and disadvantages of different treatments.

Conclusion

Using off-loading devices generally promotes ulcer healing in patients with DM. Here, we compared off-loading methods for active diabetic foot ulceration (TCC, FOS, RCW, HS, and SRB). TCC was identified as the most effective off-loading method despite its adverse effects on ulcers in patients with diabetic foot.

Footnotes

Declaration of Conflicting Interests

The author(s) declared no potential conflicts of interest with respect to the research, authorship, and/or publication of this article.

Funding

The author(s) received no financial support for the research, authorship, and/or publication of this article.

ORCID iDs

Susana Velasco-Rodríguez-Rabadán

Aroa Tardáguila-García

Marta García-Madrid

Mateo López-Moral

José Luis Lázaro-Martínez

References

OMS | Diabetes. WHO [Internet]. 2017. Accessed February 24, 2021. http://www.who.int/topics/diabetes_mellitus/es/

Allison

Flanagin

. How ESKD complicates the management of diabetic foot ulcers: the vital role of the dialysis team in prevention, early detection, and support of multidisciplinary treatment to reduce lower extremity amputations. Semin Dial. 2020;33(3):245-253.

Pitocco

Spanu

Di Leo

, et al. Diabetic foot infections: a comprehensive overview. Eur Rev Med Pharmacol Sci. 2019;23(2 Suppl):26-37.

Alexiadou

Doupis

. Management of diabetic foot ulcers. Diabetes Ther. 2012;3(1):4.

Lazaro-Martinez

Aragon-Sanchez

Alvaro-Afonso

Garcia-Morales

Garcia-Alvarez

Molines-Barroso

. The best way to reduce reulcerations: if you understand biomechanics of the diabetic foot, you can do it. Int J Low Extrem Wounds. 2014;13(4):294-319.

Mulder

Tenenhaus

D'Souza

. Reduction of diabetic foot ulcer healing times through use of advanced treatment modalities. Int J Low Extrem Wounds. 2014;13(4):335-346.

Everett

Mathioudakis

. Update on management of diabetic foot ulcers. Ann N Y Acad Sci. 2018;1411(1):153-165.

Perez-Favila

Martinez-Fierro

Rodriguez-Lazalde

, et al. Current therapeutic strategies in diabetic foot ulcers. Medicina (Kaunas). 2019;55(11):1-21.

Eleftheriadou

Samakidou

Tentolouris

Papanas

Tentolouris

. Nonpharmacological management of diabetic foot ulcers: an update. Int J Low Extrem Wounds. 2021;20(3):188-197.

10.

Moher

Liberati

Tetzlaff

Altman

Group

. Preferred Reporting Items for Systematic Reviews and Meta-Analyses: the PRISMA statement. Open Med. 2009;3(3):e123-e130.

11.

Armstrong

Nguyen

Lavery

van Schie

Boulton

Harkless

. Off-loading the diabetic foot wound: a randomized clinical trial. Diabetes Care. 2001;24(6):1019-1022.

12.

Potier

Francois

Dardari

, et al. Comparison of a new versus standard removable offloading device in patients with neuropathic diabetic foot ulcers: a French national, multicentre, open-label randomized, controlled trial. BMJ Open Diabetes Res Care. 2020;8(1):1-11.

13.

Najafi

Grewal

Bharara

Menzies

Talal

Armstrong

. Can't stand the pressure: the association between unprotected standing, walking, and wound healing in people with diabetes. J Diabetes Sci Technol. 2017;11(4):657-667.

14.

Armstrong

Lavery

Boulton

. Evaluation of removable and irremovable cast walkers in the healing of diabetic foot wounds: a randomized controlled trial. Diabetes Care. 2005;28(3):551-554.

15.

Bus

van Netten

Kottink

, et al. The efficacy of removable devices to offload and heal neuropathic plantar forefoot ulcers in people with diabetes: a single-blinded multicentre randomised controlled trial. Int Wound J. 2018;15(1):65-74.

16.

Gutekunst

Hastings

Bohnert

Strube

Sinacore

DR.

Removable cast walker boots yield greater forefoot off-loading than total contact casts. Clin Biomech (Bristol, Avon). 2011;26(6):649-654.

17.

Katz

Harlan

Miranda-Palma

, et al. A randomized trial of two irremovable off-loading devices in the management of plantar neuropathic diabetic foot ulcers. Diabetes Care. 2005;28(3):555-559.

18.

Piaggesi

Macchiarini

Rizzo

, et al. An off-the-shelf instant contact casting device for the management of diabetic foot ulcers: a randomized prospective trial versus traditional fiberglass cast. Diabetes Care. 2007;30(3):586-590.

19.

Van De Weg

Van Der Windt

Vahl

. Wound healing: total contact cast vs. custom-made temporary footwear for patients with diabetic foot ulceration. Prosthet Orthot Int. 2008;32(1):3-11.

20.

Lavery

Higgins

La Fontaine

Zamorano

Constantinides

Kim

. Randomised clinical trial to compare total contact casts, healing sandals and a shear-reducing removable boot to heal diabetic foot ulcers. Int Wound J. 2015;12(6):710-715.

21.

Miyan

Ahmed

Zaidi

Ahmedani

Fawwad

Basit

. Use of locally made off-loading techniques for diabetic plantar foot ulcer in Karachi, Pakistan. Int Wound J. 2014;11(6):691-695.

22.

Faglia

Caravaggi

Clerici

, et al. Effectiveness of removable walker cast versus nonremovable fiberglass off-bearing cast in the healing of diabetic plantar foot ulcer: a randomized controlled trial. Diabetes Care. 2010;33(7):1419-1423.

23.

Caravaggi

Sganzaroli

Fabbi

, et al. Nonwindowed nonremovable fiberglass off-loading cast versus removable pneumatic cast (AircastXP Diabetic Walker) in the treatment of neuropathic noninfected plantar ulcers: a randomized prospective trial. Diabetes Care. 2007;30(10):2577-2578.

24.

Ha Van

Siney

Hartmann-Heurtier

Jacqueminet

Greau

Grimaldi

. Nonremovable, windowed, fiberglass cast boot in the treatment of diabetic plantar ulcers: efficacy, safety, and compliance. Diabetes Care. 2003;26(10):2848-2852.