Table 28.1 A general guide to footwear prescription based on risk status
Prior plantar Activity ulcer/deformity/callus/ high plantar pressure Low Moderate High
No Sports shoe with a Sports shoe or Sports shoe or soft insole extra-depth shoe with extra-depth shoe with a thick insole a thick insole; consider rocker bottom Yes/moderate Sports shoe or Sports shoe or Sports shoe or extra-depth shoe extra-depth shoe with extra-depth shoe with with a thick insole a thick insole, a thick insole, metatarsal pads or metatarsal pads or bar, bar; consider rocker rocker bottom; bottom consider custom insole Yes/severe Customised upper or Customised upper or Customised upper or custom shoe, thick custom shoe, thick custom shoe, thick insole; consider custom insole with custom insole with custom insole reliefs, rocker bottom complex reliefs, rocker bottom
Adapted from Ref. 26.
patient who is habitually more active will require greater protection, although the few studies that are available are equivocal on this issue.33−35 All of these factors can be put together in the risk matrix shown in Table 28.1, which guides the prescriber towards an appropriate level of footwear intervention.
The Newly Diagnosed Diabetic Patient Many patients who are newly diagnosed with diabetes will visit a foot specialist for a ‘foot check-up’ because they know that diabetes carries an increased risk for foot complications.
In- variably, these patients will have good pulses, good sensation and no significant foot deformity and will not, therefore, have special requirements in footwear.
The provider should take the opportunity to explain why they are not ‘at risk’ for immediate foot problems and to suggest that they return for an annual examination to reassess their risk.
It is not too early for these individuals to begin adopting good footwear habits, and they should be educated at every visit to their physician about the need for shoes that do not apply excessive loads to the foot, on either the dorsal or the plantar surfaces.
Patients should shake out their shoes before putting them on, carefully wash and thoroughly dry their feet daily (including the web spaces) and begin to inspect their feet regularly.
The Patient Who Is at Risk for an Ulcer How to perform a foot examination to help determine the risk for ulceration or other foot injury is described elsewhere in this volume (Chapter 6). The most important sign is loss of protective sensation (LOPS), implying that the patient cannot feel the stimuli that would
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344 FOOTWEAR FOR PEOPLE WITH DIABETES
otherwise be interpreted as leading to foot injury.
LOPS alone is sufficient to result in ulceration, e.g. if the patient were to wear shoes that apply pressure along the lateral border of the foot.
However, when LOPS is combined with foot deformity, the risk is likely to be even greater.
Special prescription footwear should always be provided in such cases.
The deformity may be obvious (a large bunion, for example) or more subtle (a mildly prominent MTH).
There may be indications of the at-risk areas such as redness, warmth or callus (which has been shown to be a risk factor for ulceration).36 A first line of defense for at-risk patients, as shown in Table 28.1, is a quality sports shoe, as long as any deformity can be accommodated.
Sport shoes can reduce plantar pressures compared to conventional shoes37 and can also reduce the accumulation of callus.38 There will, however, be some patients who cannot safely wear sports shoes because of their need for more cushioning in certain locations under the foot or their significant foot deformity.
For example, toes that are dorsally prominent because of clawing or hammering will need more room in what is called the ‘toe box’ , the front part of the shoe.
In such cases, the patient will need an extra-depth shoe or a super-extra-depth shoe,39 which have, respectively, approximately 1/4 and 1/2 in. (6 and 13 mm) of additional space in the toe box.
This space can accommodate prominent toes when a normal insole is used, or, in patients without dorsal deformity but with plantar prominences, allow the use of a thick insole or orthosis with features that distribute pressure or unload regions of focal pressure.
Certain deformities will need to be accommodated by stretching a specific region of the shoe upper, using special tools.
Some shoes are designed to stretch easily when heated.
In many instances, a thick ‘off-the-shelf’ insole without customisation or modification will suffice, but in a patient who is at least moderately active or has at least moderate foot deformity, customisation of the insole will be required.
Cost is usually an issue in the prescription because (as short sighted as such a policy is) many health services will not pay for primary prevention.
The Diabetic Patient with an Ulcer With rare exceptions, shoes should not be worn at all by diabetic patients with active ulcers, except special prescription shoes (sometimes called ‘half shoes’40 ), which isolate regions of the foot completely from weight bearing.
Patients who walk into an examination room wearing the very shoes in which their foot became ulcerated should not walk out wearing those same shoes.
Some form of offloading such as a cast or other device (Chapters 25 and 30) must be immediately employed until the ulcer is healed.
However, while an ulcer is healing, the practitioner should be making plans for the footwear that the patient will need after the ulcer has healed; any delay in providing definitive footwear to the patient, after the treated ulcer has healed, can result in rapid re-ulceration in the same or an associated area.
Any impressions that need to be taken of the foot (for custom-made insoles, for example) can be made even on the healing ulcer if it is fully covered with a clear film dressing.
The Diabetic Patient with a Recently Healed Ulcer The first few weeks following return to normal ambulation after ulcer healing is a period of very high risk, and it may be preferable to transition the patient into new therapeutic footwear by providing a very well-cushioned walking splint or orthopaedic walker to enable the fragile new
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CHOOSING THE APPROPRIATE FOOTWEAR FOR THE PATIENT 345
tissue to consolidate.
Recurrence of foot ulcers is a significant clinical problem.41 Estimates of recurrence range from 28% at 12 months42 to 100% at 40 months.16 It has been suggested that ulcer-free survival should be used as an indicator of the effectiveness of foot ulcer management in different centres.43 Once a patient’s ulcer has healed, the clinician needs to mount a major initiative, first, to get the patient into appropriate therapeutic shoes, and second, to convince the patient that wearing the shoes may be critical to preventing another ulcer and a possible amputation (see below).
Since there is a high likelihood that the original ulcer was footwear related, the patient’s previous footwear is often not a good starting point for the new footwear prescription.
It can, however, be an extremely useful piece of evidence of what did not work and can guide the next iteration of footwear.
Depending on the patient’s level of activity and extent of foot deformity (Table 28.1), the practitioner will need to be prepared to take extraordinary steps to provide a protective shoe.
This will likely involve a footwear professional who can implement necessary modifications to the foot, shoe interface and convert the shoe into one with a rocker sole, if needed.
Sizing the shoe to accommodate thick socks and insoles provides another means of reducing the pressure on the foot,44 but care must be taken to ensure that this does not result in excessive pressure on the dorsum of prominent toes.
As with all new footwear, the patients should wear their new shoes in a graduated manner, starting with a few hours per day, after which they, or a companion, should inspect their feet carefully.
Any excessive redness or damage to the skin should be the trigger for an immediate return visit to the footwear provider for modifications.
Unfortunately, the prescription and dispensing of therapeutic shoes is still very much a trial-and-error process, and it is not unusual for a new pair of shoes to require several such modifications before they are satisfactory.
In addition to a pair of shoes for use outside the home, several centres also provide custom- moulded sandals or slippers to patients with healed ulcers for use in the home.
This implicitly acknowledges that patients are unlikely to wear their therapeutic shoes consistently at home and provides an interface that is better than that during barefoot walking.
Since many diabetic patients wake during the night to urinate, footwear that can be easily slipped on may make the difference between staying healed and creating new ulcers resulting from barefoot walking.
Occasionally, the practitioner will recognise that the patient’s most dangerous activities from a foot injury standpoint occur during an activity for which the prescribed shoes cannot be worn.
One example was a factory worker for whom it was necessary to make extra-depth shoes with steel toecaps, and another was a special pair of shoes for horse riding.
In such cases, an effort should be made to provide a footwear solution that facilitates the activity and prevents injury.