Offloading
(Removing Pressure and Friction From An Ulcer)

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If there's on thing to learn from this website it is this: 

 

For most neuropathic wounds, the single most important
factor in wound healing is offloading.  

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If you can remember that, you'll know how to heal most

neuropathic / diabetic wounds. 

 

So what is offloading? 

 

Offloading is the removal of pressure and friction from a wound. 

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And it is important because neuropathic wounds are caused by a combination of neuropathy (the loss of normal sensation that serves to warn us of damage to our  feet), combined with pressure and friction (shear)--the forces

that damage our feet.  

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At this point in time, medicine cannot cure the sensory loss neuropathy.  So we must control the other side of that equation--the pressure and shear.  And removing pressure and shear from a wound is the definition of offloading.

 

Look at it from your body's perspective.  An ulceration like the one

to the right, develops on the bottom of the foot from pressure and

friction.  

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The body produces fragile skin cells in the attempt to heal a wound,

all the while fighting off bacteria that have entered the wound. 

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And because neuropathic patients can't feel pain, they don't know

there is a problem.   So they walk on the foot, with every step

applying the weight of our entire body on those fragile skin cells,

destroying them with each step.  

 

We must protect our feet.

  

As important as offloading is, it is unfortunate that most provincial

health insurers won't pay for devices to offload wounds.  Instead of

covering the one thing most likely to heal a wound, provincial health

authorities have chosen to pay for endless dressing changes,

hospitalizations for infections and amputations in non-responsive wounds. 

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Regardless, offloading a wound is vital to get it to heal, so let's discuss it, and how it can be performed.  

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So how can ulcers be offloaded?  

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There are many ways to offload, or remove pressure from an ulceration, and each has pluses and minuses.  Statistically, the most effective way of getting an ulcer to heal is with a non-removable device, such as a total contact cast or a non-removable walking boot.  But these may not be practical in all cases. 

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So the best choice in an individual case depends upon factors such as the severity of the wound, the location of the wound, the age, health, and fitness of the patient.  We'll review a variety of ways wounds are offloaded, discuss the pluses and minuses of each, and give you some recommendations.

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Let's start with some common techniques for simpler wounds. 

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Accommodative Felt Padding

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Offloading may be achieved with accommodative padding to redistribute weight from a wound.  This is sometimes known as a poor-man's cast. 

 

The way it is done is by placing a thick piece of felt or similar non-compressive material around the wound, (but not on the wound), as seen in the two patients below.  On the left is a thick pad offloading a 4th metatarsal head (the bone to which the 4th toe attaches) before a wound bandage and cover is applied.  To the right is a pad offloading the 2nd metatarsal head (where the 2nd toe attaches to the foot), with the dressing and cover applied.

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The idea is to redistribute weight away from the ulcer by building up the surrounding areas so that area bears more weight.  In these examples the felt is 1/4" thick, though different thicknesses may be used. 

 

A dressing of some sort is applied over the wound.  Perhaps it's a simple non-adherent bandage, perhaps it's a dressing to add or remove moisture, perhaps the dressing is something else.  The felt pad and wound dressing would then be covered over in some fashion, as you see in the photo on the upper right.  

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Felt padding has fallen out of favor for some, yet it remains one of the most common ways to offload a wound.  And there is a fair bit of support in the literature for the suggestion that accommodative padding is effective in offloading wounds.

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Zimny S, Meyer MF, Schatz H, Pfohl M. Applied felted foam for plantar pressure relief is an efficient therapy in neuropathic diabetic foot ulcers. Exp Clin Endocrinol Diabetes. 2002 Oct;110(7):325-8.  PubMed PMID: 12397530.

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Nube V, Molyneux L, Bolton T, Palmer E, Yue D. The use of deflective padding in the management of plantar hallux and forefoot ulcers in people with diabetes. Foot. 2006;16(1):38–43. doi: 10.1016/j.foot.2005.11.005.

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As one might imagine, thicker accommodative felt padding applied around the wound reduces pressure on an ulcer by a greater degree than thinner padding. 

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Curran, M, Ratcliffe, C; Campbell, J  A comparison of types and thicknesses of adhesive felt padding in the reduction of peak plantar pressure of the foot: a case report.  J Med Case Rep. 2015; 9: 203.  Published online 2015 Sep 24. doi: 10.1186/s13256-015-0675-8 PMCID: PMC4581116 PMID: 26400619

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This is one reason that studies suggest that padding reduces pressure by varying amounts.  For example, on the lower end, this British study found that peak pressure (PP) and pressure time integral (PTI) at the ulcer site was cut by 25%-29%. 

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Paton J, Woodrow T, Passmore C. The effect of plantar cover padding with U'd cut-out on plantar foot pressure; preliminary study. Brit J Podiatry. 2007;10(3):110–5

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This Australian study found pressures dropped by 49% with accommodative padding.

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Raspovic A, Waller K, Wong, WM  The effectiveness of felt padding for offloading diabetes-related foot ulcers, at baseline and after one week of wear  Diabetes Research and Clinical Practice November 2016 Volume 121, Pages 166-172  DOI: https://doi.org/10.1016/j.diabres.2016.09.018

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And this German study found accommodative padding reduced pressure by 70%, from 297.3 ± 120.0 kPa before to 90.3 ± 38.2 kPa. 

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Zimny S, Reinsch B, Schatz H, Pfohl M. Effects of felted foam on plantar pressures in the treatment of neuropathic diabetic foot ulcers. Diabetes Care. 2001;24(12):2153–4. doi: 10.2337/diacare.24.12.2153.

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And as you might expect, because felt tends to compress with time, newly-applied padding diminishes pressure on a wound better than worn padding.  

 

Pressure  averaged 367.2 kPa with no padding; 188.0 kPa with fresh padding; 248 kPa with worn padding.

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Raspovic A, Waller K, Wong, WM  The effectiveness of felt padding for offloading diabetes-related foot ulcers, at baseline and after one week of wear  Diabetes Research and Clinical Practice November 2016 Volume 121, Pages 166-172 
DOI: https://doi.org/10.1016/j.diabres.2016.09.018

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Pressure averaged 297.3 ± 120.0 kPa with no padding to 90.3 ± 38.2 kPa, and it maintained the strong offloading force for 3-4 days before diminishing. 

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Zimny S, Reinsch B, Schatz H, Pfohl M. Effects of felted foam on plantar pressures in the treatment of neuropathic diabetic foot ulcers. Diabetes Care. 2001;24(12):2153–4.

doi: 10.2337/diacare.24.12.2153.

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Beyond relieving pressure, accommodative felt dressings work.  In this 2002 study out of LSU, researchers found that 81% of forefoot wounds healed within 12 weeks if treated by felt.

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Birke JA, Pavich MA, Patout CA Jr, Horswell R.  Comparison of forefoot ulcer healing using alternative off-loading methods in patients with diabetes mellitus.  Adv Skin Wound Care 2002 Sep-Oct;15(5):210-5.

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If a practitioner wishes to consider using felt, it's worth noting its advantages and disadvantages relative to other offloading techniques. 

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Some advantages to using accommodative felt to offload a wound are: 

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• Felt is inexpensive.   

• It doesn't require a sophisticated skill set to apply.  

• It's not as bulky as some of the other forms of offloading discussed below, so it's not uncomfortable and doesn't make the foot unstable. 

• It has the benefit of staying on the foot even when the patient isn't wearing a shoe. 

• The patient can drive with it.

• It doesn't lift the treated leg excessively throwing off the opposite limb.  So it doesn't typically tend to irritate the back or make walking difficult or unstable.

• The patient and clinician can also keep an eye on the foot for signs of infection or discharge with this technique.

• Patients tend to be compliant with it, and don't typically remove it.

• It's easily removed if there is a problem of some sort.  

• And it can be coupled with other forms of offloading, to augment the effectiveness of offloading.

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Some of the downsides to using accommodative felt to offload a wound are:

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• The padding can compress or slide, which can make it ineffective. 

• It can create new pressure issues at the edge of the pad, if not cut and applied correctly.

• The patient can't get the foot wet, as the padding will absorb water. (Though one doesn't usually want the wound to get wet anyway.)

• As a rule, thicker padding is more effective than thinner felt padding.  However, it can be hard to source padding that is thick enough.  We can find thin felt padding at Canadian medical supply facilities, but our office must import thick padding.  

• Accommodative padding works better for  simpler ulcerations on the ball of the foot or great toe than ulcers in the midfoot or rearfoot. 

• And felt padding is less effective than other means of offloading discussed below, particularly for midfoot or rearfoot ulcers, or for more complicated ulcers in the forefoot.  On average it diminishes pressure on a wound by about 45%.

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Our Bottom Line on Accomodative Felt Padding:

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By itself, padding is not statistically the most effective way to offload a wound.  That honor

is reserved for non-removable offloading systems such as the Total Contact Cast (TCC) or a

non-removable offloading boot, both of which are discussed below. 

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Nonetheless, accommodative felt dressings can be effective if applied correctly, particularly

for simpler wounds located in the forefoot, or in wounds where other options of offloading

are contraindicated for some reason.  Further, it's easy to use, it's cheap, and it offers a high

degree of acceptability to most patients.   

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It doesn't work as well for midfoot or rearfoot wounds.  And generally speaking, when this

method is employed, the preference is to couple it with offloading footwear, as discussed

below.

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Off-the-Shelf Shoes and Sandals & Customizable Innersoles

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A variety of footwear products have been used for foot ulcers.  And they've been shown to work with most forefoot ulcers.

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Birke JA, Pavich MA, Patout CA Jr, Horswell R.  Comparison of forefoot ulcer healing using alternative off-loading methods in patients with diabetes mellitus.  Adv Skin Wound Care 2002 Sep-Oct;15(5):210-5.

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Perhaps the simplest is a standard surgical shoe (right).  While

some physicians use a surgical shoe as its own offloading tool,

a surgical shoe like this is rather ineffective at offloading  wound. 

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It should be used with a customizable, offloading innersole.  We'll

discuss the shoe first, then discuss an appropriate innersole.

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A surgical shoe like this one uses a velcro closure that can be

easily adjusted for the thickness of a bandage and a customizable

innersole.

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The sole of the shoe does not bend like a regular shoe, which can decrease pressure and strain of bending of the joints in the ball of the foot during gait.

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The heel height is made to be similar to a regular shoe on the opposite limb, making it easy on the back.

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And the sole has good grip, making them suitable for use in Canadian winters.

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Another benefit of a shoe like this is that it is removable for sleeping.  The patient doesn't have to wear a dirty shoe that's been on the street to bed. 

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They're also cheap enough that patients will often choose to buy two--one for inside the house, and one for the street.

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But its being removable is also a downside.  Because it can be removed, it often is, and patients may not use it when weight bearing.  So only very compliant patients can use this effectively.

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But this shoe does not, by itself, offload a wound effectively.  The innersole a surgical shoe comes with is not customizable, nor does it offload a wound.  Thus a shoe like this needs to be coupled with an offloading innersole of some sort, like seen below. 

 

 

There are several types of customizable innersoles for a shoe like this.

 

One of the most common innersoles used in a shoe like this consists of several layers  of foam.  Plugs can be removed from the bottom of the innersole, creating a hole in the area of the ulcer, meant to offload the ulcer.  

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The idea of this makes intuitive sense. 

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Our Bottom Line on Surgical Shoes and Offloading Innersoles

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A flat-soled surgical shoe like the one above with an innersole system like the FORS may

work well to treat a smaller, simpler wound of the forefoot.  

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With this said, we tend not to use this on its own.  We prefer to couple this system with a 

accommodative, felt dressing applied to the foot.  No study combining a FORS innersole

in a surgical shoe and an accommodative, felt dressing has been done, but it has been

our experience that the combination improves wound healing success.

 

With this said, it is our opinion that it works better for smaller, simpler wounds of the

forefoot, less well for midfoot and rearfoot lesions. 

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They need to be used in patients who can be trusted to be compliant.  If the patient

removes them because they're "just going to the bathroom," or "just going  to the

kitchen," they are often not used enough to allow for uneventful healing.  

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Healing Shoes and Sandals

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Other offloading shoes on the market are offloading shoes and sandals.  These shoes are better made and more substantial than those above--with a better heel counter that better controls side-to side movement (shear).  These shoes are therefore more expensive. 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

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To provide offloading, these shoes come with a set of customizable innersoles.  In the example below, offloading is achieved not through the removal of plugs, but through apertures cut into the middle layers of the innersole system.     

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We have found shoes and sandals like these can be effective.  Though when these shoes are used by the author of this webpage in the treatment of active wounds, the shoes and innersoles are coupled with an offloading felt dressing.

 

The shoes and sandals are well made, and the innersole system it comes with is not bad.  The quality will vary based on the brand of offloading shoe / sandal.  Still, our preference is for the FORS innersole system discussed above, so we will often begin with the innersoles the shoe comes with, then trade them for a FORS innersole when the original system begins to wear.  

 

As with all removable offloading devices, they're dependent upon the patient to use with each and every step.  Patients who cannot be trusted to wear these shoes religiously should be placed in a non-removable system like a Total Contact Cast (TCC) or a non-removable boot.  Both are discussed below.  

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There are a few downsides to shoes and sandals.  First, they are more costly than the simple surgical shoe we described above.  But these are better made and many patients feel they're worth the added cost. 

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However, in order to fit in four innersoles, these shoes and sandals have to be deep.  This means the soles are quite elevated, and they can be unstable for some patients, especially the elderly, the frail, and those who are unsteady with neuropathy or some other issue. 

 

This is especially true when only one sandal or shoe is used at any one time, with normal footwear on the other foot.  Thus using only one shoe on the foot with the wound along with a lower-height street shoe on the other limb can make it hard on the back.  So most patients buy the pair of shoes, even if there is a wound on just one foot.

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One other common complaint we find for our Canadian patients in winter is that the sole is quite smooth, making them less practical in the winter.  

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Our Bottom Line on Offloading Shoes and Sandals  

 

The good:  Very well-made footwear, ideal for those who want more lateral stability

than a surgical shoe can offer.  They hold up well enough that some patients like them

for the long term, even after the ulcer has healed. 

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The not-so good:  The 4-layer offloading system that comes with the shoe is better

than some, but not as good as others, such as the FORS.  The place the foot high, and

can be unstable for some.  The sole has minimal tread for winter.

 

 

 

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Wedge Shoes

 

One footwear option commonly used in Canada are these 

wedged, half-soled shoes.

 

They can be made with the forefoot elevated (left) to relieve pressure in the forefoot, or with the rearfoot elevated (below left) to relieve pressure in the rearfoot.

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These shoes have a removable innersole, so one could use a customizable offloading innersole with it, like the one shown above.  But these shoes are usually just given out as is, with no customized innersole.  

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While these shoes can decrease the forces on an ulcer by up to 50%, they come with some significant downsides.  For example, they're quite a bit elevated compared to normal shoes, or to the flat surgical shoe above.  They make one limb higher than the other, which can be uncomfortable for the back. 

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Further, the cliff-edge design can make transfer of weight forward jarring and clumsy.  They can make the patient unstable, and more prone to falls.  

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They're also not as good as other offloading options.   In one study, shoes like this offered healing rates of just 58%, and they took nearly twice as long to heal as a total contact cast.

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Armstrong DG, Nguyen HC, Lavery LA, van Schie CH, Boulton AJ, Harkless LB.  Off-loading the diabetic foot wound: a randomized clinical trial. Diabetes Care.

2001 Jun;24(6):1019-22. Erratum in: Diabetes Care 2001 Aug;24(8):1509. PubMed  PMID: 11375363.

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​​Total Contact Cast (TCC)

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A total contact cast or TCC is a specially-designed cast used to

treat neuopathic wounds and Charcot neuroarthropathy. 

 

The TCC redistributes weight from the wound, sheltering it from

the pressure and sheer forces that create ulcerations. 

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They're somewhat awkward and clumsy.  Patients using them take
shorter steps and fewer steps.  They're typically changed weekly.

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The big benefit to a TCC is that the foot is kept safe and sheltered

from the pressure and sheer forces that create ulcerations.  TCCs

simply work better than anything else, making it the gold standard

in offloading neuropathic foot ulcers.  For this reason, TCCs have

long been this author's favorite method of offloading difficult

wounds, and wounds of the midfoot and rearfoot.

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TCCs are so effective that we can consistently get 90% healing

rates within 6-8 weeks.  Below we see a chart of nine studies showing

the healing rate of ulcers treated with a TCC.

 

 

 

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Ulcers also heal pretty quickly with a TCC.  If we compare the results of twelve studies from several different countries, TCCs heal ulcers in an average of 39.1 days or 6 weeks, with most studies falling into an average of between 5 and 8 weeks.

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

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How do total contact casts compare to other treatment options?  When we compile data from these various studies, (below), we find that TCCs have higher healing rates (red bars) and faster healing times (blue line) compared to other treatment options.

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One reason the TCC performs well is that it is very solid, and it effectively distributes weight away from

the wound. Further, it keeps the ankle at 90 degrees, diminishing the deforming forces when the foot

pushes off.  It also shortens the patient's stride and diminishes the number of steps taken.  Perhaps the primary reason for the TCCs superior success, though, is that it's not removable by the patient.  It

enforces compliance. 

In severe wounds, particularly in midfoot and rearfoot wounds, the TCC is often vital. 

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So if TCCs are so great, why doesn't everybody use them? 

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TCCs are used somewhere between 5 and 10% of wound care clinics in North America.  And even though they are this author's favorite way to offload a wound, even I use them in less than half of all ulcers.

 

There are several reasons they're not used frequently. 

 

• First, TCC application requires a degree of specialized training.  And training people to apply TCCs is not something the provincial health systems appear to be prioritizing. 

• Casts are relatively expensive, and they're typically removed and reapplied weekly, adding to the expense.  And that cost is not typically covered by most Canadian provincial health programs. 

• Some podiatric wound specialists apply them, but they are mostly private-paid.  

• TCCs are time consuming to put on and take off, particularly if the clinician doesn't have a lot of experience with them.  

• TCCs have the potential to cause harm--abrasions, pressure--that can create new ulcers, particularly if the foot and leg swells a lot or if it's improperly applied.  This is not a major problem in most cases, however, particularly for practitioners who apply a lot of TCCs.

• You also can't use it with infected wounds, and you might miss new infections while the patient is sealed up in a cast.  

• TCCs can also be unstable for the elderly and those with balance issues. 

• It's hard to drive with a TCC on the right foot.

• Those sensitive to claustrophobia may not enjoy a TCC. 

• You can't bathe easily with it. 

• It can be cumbersome to sleep with a TCC. 

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Nonetheless, TCCs do have success rates higher than any other offloading technique, and if you have a difficult wound, particularly in the midfoot or rearfoot, it may be the treatment of choice. 

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Our Bottom Line on Total Contact Casts (TCCs) 

 

There are some contra-indications for TCCs, and you can't use them on every ulcer patient. 

There are times when other offloading methods may be preferable because they are simpler,
more economical, and more practical in terms of function in every day life.

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But the bottom line is that multiple studies show that TCCs are the most effective offloading

option, the gold standard, with healing rates of approximately 90% in 6 to 8 weeks.  And

TCCs are usually the first choice for midfoot wounds, for rearfoot wounds, and for wounds

that are non-responsive to other offloading techniques.  

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To learn how they're put on the foot, we have a page on the application of a Total Contact Cast here.

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CROW Boot

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A CROW boot (where CROW stands for Charcot Restraint Orthotic Walker) is a custom-made boot similar in external appearance to an offloading boot like those discussed above, but it's custom made, and the inside is more similar

to a TCC.    

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In theory, the CROW should be as safe and comfortable as a TCC, but unlike the TCC, a CROW boot is removable. 

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The benefit to a CROW boot being removable is that it allows the patient to take it off at night to sleep or to bathe. 

 

The downside is that the patient may take it off and not use it consistently.  It's also takes some time to make--sometimes the ulcer is healed by the time the CROW is ready.  And as a CROW boot is custom made, it can be rather costly. 

 

For these reasons the CROW is often reserved more for Charcot neuroarthropathy (which is what it is really

intended for) than a routine ulcer. 

 

But these can be quite helpful to treat ulcers as well, particularly in difficult wounds, or as a long-term offloading option for difficult wounds.

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Our Bottom Line on CROW Boots. 

 

CROW boots are costly and take time to make, so they're not practical to treat most 

wounds.  

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They may be a very good option for slow-healing wounds, or as a long-term offloading

option for certain wounds with an unstable or problematic foot structure. 

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They're excellent options for Charcot patients, who need longer-term offloading 

options.  

 

 

 

 

 

 

 

 

 

Long-term offloading

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Once the ulcer is healed, there is a need for long-term offloading, otherwise the wound tends to return.  There are various devices that can offload a toe ulcer long-term.  

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For toes, often simple digital offloading devices are more helpful than more expensive inserts or shoes.  For digital ulcers, simple surgical options are often very helpful too, which we discuss here.

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Ulcers in the ball of the foot, arch or rear foot may be offloaded through an orthotic with an accommodation (depression) built in (below left), or through a custom shoe (below right is a custom, steel-toed work boot), with similar offloading built in.

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What about getting all the patient's body weight off the wound? 

 

For instance, a wheelchair could offload a wound completely. 

The downside is that it's not convenient or practical for patients, and not really healthy for a patient to sit for weeks on end while a wound heals.  And it may not be healthy for the skin either, as there is some evidence that being completely immobile may cause the skin to atrophy and  weaken, making future ulcers more likely.

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Crutches could completely offload a wound, too.  But they can be

uncomfortable and unstable for many.  Further, there's a significant

tendency for patients to be non-compliant and use the crutches only

intermittently. 

 

They're more likely to be effective for younger, fitter patients, but

younger, fitter patients are not typically those who present with a

wound.  Thus we rarely recommend crutches to offload a wound.

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There are kneeling scooters (right) that can be used for complete

offloading.  These are often more stable than crutches, and we do

recommend them in patients who need complete offloading, in

those we trust to be compliant, and those stable enough to use

them. 

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However, the continued pressure on the knee can prove

uncomfortable.  

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While techniques to completely offload the foot are sometimes

necessary, but when possible, we try to keep the patient offloaded

while still able to walk.

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