FELTED FOAM PADDED DRESSINGS Padding techniques that use glue or tape to secure a pad around or over an ulcer on the sole of the foot have also been reported in the medical literature with success.
This type of technique can be used in the patients’ shoes if they have a deep toe box, with healing sandals or in removable cast boots (Plate 4).
This is an easy technique to use and can be mastered by many members of the health care team.
This technique involves two basic materials, adhesive felt and adhesive foam.
The non-ulcerated skin is usually prepared with a standard skin adherent for protection and to assist in keeping the felt in place.
The felt, which can be of different
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302 CONVENTIONAL OFFLOADING AND ACTIVITY MONITORING
Figure 25.5 (a,b) Custom healing sandal
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thicknesses (typically 0.125 in., 0.25 in.), is cut to support the areas around the ulcer site, taking into account specific anatomical variations.
Additional pieces of felt can be added as needed to effect a flat plantar surface (much like the TCC concept).
The ulcer is treated with the topical and primary dressing to fill the apertured part of the felt.
The foam is then cut to cover the entire dressing including the felt and ulcer site.
Tape is then utilised to seal the edges.
It is a quick and inexpensive technique.
However, patients must leave it in place for a week at a time.
It is often malodorous and surrounding soft tissue is easily macerated.
Healing with this offloading approach is usually less successful than with more aggres- sive immobilisation.
Zimny et al.29 compared felted foam padded dressings to conventional wound therapy and found that healing times were almost identical.
The padded dressing group healed in 79.6 days (range 75, 84 days) compared to 83.2 days (range 77, 90 days) using conventional therapy.
In contrast, Birke and colleagues30 reported an average heal- ing time of 36 days with 93% complete wound closure, using felted foam in a retro- spective cohort of diabetic foot wounds.
Special load-relieving dressings are also available (Chapter 30).
THERAPEUTIC SHOES AND INSOLES Therapeutic shoes and insoles are often the easiest choice for the busy clinician.
They are always a choice of compromise for patients that cannot tolerate other offloading strategies.
They are widely available, but manufactured with considerable variability in quality, customi- sation and effectiveness.
Therapeutic shoes and insoles offer only a fraction of the pressure reduction at the site of ulceration provided by casts, removable cast boots or even padded dressings and healing sandals (Table 25.2).22 The magnitude of pressure reduction is vari- able and depends on the location of the ulceration.
In a gait lab study, therapeutic shoes with insoles reduced pressure at the site of ulceration in a wide range, from 3.4 to 48.4% (Table 25.3).31 Data regarding the effectiveness of therapeutic shoes and insoles are sparse.
Most often, therapeutic shoes and insoles have been used as a control group in clinical trials of advanced
Table 25.2 Pressure reduction with removable cast walkers, half shoes, felted foam and surgical shoes
% Changea Great toe Forefoot Modalities ulcer group ulcer group
Royce walker 79 85 Total cotact cast 85 76 Half shoe 64 66 Felted foam dressing 34 48 Post-operative shoe 7 36
a Percent change from the baseline measurements in canvas Oxford shoes.
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Table 25.3 Percent pressure reduction from baseline among diabetic patients with foot ulcers treated with off-the-shelf footwear with and without accommodative insoles
Xtra Depth Cross Trainer San Antonio shoes
Insole Yes No Yes No Yes No First metatarsal 42.9 28.5 42.6 34.7 45.0 41.3 Second to fifth 47.2 38.8 45.5 41.4 48.4 45.4 metatarsal Great toe 18.3 8.8 3.2 −12.2 16.8 6.2
wound therapies (Table 25.4).15,17 In randomised clinical trials of Dermagraft, only 18% of patients healed in 12 weeks in the control group that was offloaded with extra-depth shoes with custom insoles. In a 12-week randomised clinical trial by Mueller and colleagues,10 therapeutic shoes and insoles were evaluated against TCCs. Only 32% of subjects treated with therapeutic shoes and insoles healed, compared to 90% of subjects treated with TCCs.
Table 25.4 Healing times with shoes, healing sandals, half shoes and felted foam dressings
Offloading Mean Type of modality healing time Type of study % Healed wound References
Fibreglass cast 34 Retrospective 91 Wagner 1 Hissink et al.32 shoe cohort† Fibreglass cast, Not reported RCT* 50 Wagner 1 Caravaggi shoe and 21 et al.33 insole Scotchcast boot 130 days Retrospective 80 Wagner Knowles et al.34 cohort‡ 1, 2, 3 Fibreglass cast 69 days Prospective 81 UT 2A Ha Van et al.28 Half shoe 134 days cohort‡ 70 UT 1A Custom splint 300 days Retrospective Not reported Not stated Boninger and cohort‡ Leonard27 Felted foam 80 days RCT Not reported Wagner Zimny et al.29 dressing 1, 2 Half shoe 83 days TCC 48 days Retrospective 92 Wagner Birke et al.30 Felted foam 36 days cohort† 93 1, 2, 3 dressing Healing shoe 42 days 81 Walking splint 51 days 83
RCT, randomised clinical trial. ‡ Percentage healed no specified time. * Percentage healed in 30 days. † Percentage healed in 12 weeks. ‡ Percentage healed in 10 weeks.
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ACTIVITY AS A TREATMENT TOOL The patient’s activity is an important component of developing and healing foot wounds.
The most effective offloading devices limit activity because they restrict joint motion and make it difficult to walk.
Until recently, measurements of patients’ activity have been missing from our evaluation of cumulative stress on the diabetic foot.
With the availability of inexpensive computerised activity monitors, the ability of patients and physicians to accurately evaluate activity as a clinical tool is at hand.35,36 In many cases, persons with diabetes and foot ulcers are less active than non-diabetic and diabetic controls.
Armstrong et al.37 and Maluf and Mueller38 have reported that the variability in activity is more significant than the total numbers of steps per day.
Smoothing out the peaks and troughs may help with prevention and treatment of foot wounds.
Using embedded monitoring instruments in removable offloading devices may improve patients’ understanding of the treatment process and enhance the abysmal compliance with healing sandals and RCWs.23,28 We may be able to dose activity to facilitate healing and prevent ulceration just as we would a drug.
Or, we could simply make the offloading device in a way so it cannot be removed by the patient.
CONCLUSION Attention to offloading should be a basic element of every treatment plan for diabetic foot ulcers. It is often neglected entirely or provided half-heartedly. Offloading is not an easy part of the treatment plan for either the patient or the physician, but it is one of the most critical aspects of care.