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Let's Be Frank

Going Beyond Healing With DFU Offloading

The patient’s care doesn’t always end with a closed wound, especially when it comes to offloading and total contact casts.

As the adage goes, “an ounce of prevention is worth a pound of cure.” But what happens to diabetic foot ulcers (DFU) after they progress through the phases of healing? It’s true that our patients are ecstatic when their wounds reach closure, but does that really signal that they are finished with their wound care? It shouldn’t. And there are specific assessments post-offloading that all wound care clinicians must be vigilant about.

When it comes to chronic wound care, we focus on caring for patients through the lens of best practices. Or, at least, we should be. With DFUs, patient-centered care, when combined with best practices, yields positive outcomes. Examples of these best practices primarily include establishing adequate perfusion, maintaining adequate glucose levels, ruling out infection, promoting a moist wound environment, and offloading.

What Offloading Offers

Offloading is an important component of treating plantar DFUs because it removes abnormal and unwanted excessive biomechanical pressures that may be compounded with peripheral neuropathy. Studies indicate that offloading with total contact casting (TCC) can raise the healing rate up to 89.5% with an average of 43 days of use.1,2 As long as there are no contraindications, TCC has helped neuropathic plantar ulcers.

The TCC mechanism of action may be related to the theory of load redistribution.6 Total contact casts’ rigid material covers the entire foot, creating full contact with the foot and locking it into a neutral ankle position. As ambulation occurs, the patient will have a shorter stride with a decreasing propulsive gait, leading to less pressure to the injured area as weightbearing pressure is redistributed throughout the foot. This protects the foot from further trauma. Another theory for the mechanism of action is known as the “load sharing” theory, where the proximal portion of the cast may bear 30% of the load.3 This translates to offloading the foot by transferring weight to the walls of the cast/tibia. One study demonstrates a reduction of peak plantar pressure at the ulcer site, ranging from 81% to 92% with TCC compared to tennis shoes.4

Studies report DFU healing rates with TCC to range from 34–58 days with 50–100% healed.5 Often, clinicians recommend continuing use of the TCC for 2–3 weeks post-closure for protection, and then transitioning patients into their own prescription footwear. This is an imperative step because wounds heal by scar formation. Scar tissue reaches only 70–80% strength compared to our normal skin, and it may take approximately six weeks to reach this terminal strength. If wound care clinicians are following best practices for DFUs, it is fair to estimate that the patient’s foot will be immobilized for approximately 55–79 days from start until scar tensile strength reaches maturity.

The Other Side Of TCC

Physical therapists and wound specialists see a different perspective of DFUs post-closure and post-TCC intervention. It is rewarding to see patients excited by their healing after being offloaded, but the use of TCC may also come with some unwanted problems that are only resolved when addressed properly and promptly.

I once asked a physician, “What complications can we encounter when using TCC?” He was quick to answer that complications are rare, but if the cast is not applied properly and the foot “pistons” in the cast, then you will have complications (assuming these patients are also likely to be living with neuropathy).

The literature has reported that major complications have also stemmed from undiagnosed osteomyelitis, patient noncompliance, dermal abrasions, minor pressure ulcers, maceration, and fungal infections.6 It has also been determined that iatrogenic complications associated by TCC are low at 5.5% per cast, with the highest risk occurring when foot deformities, as with Charcot foot-related wounds, are present.7 Proper TCC application and techniques will decrease complications.7

Going Beyond TCC

Treatment is not necessarily over for the patient when the DFU ulcer is healed and no cast is warranted. When patients are in TCC, they have to adapt to new biomechanical challenges that may affect their functional status and gait. They will now walk slower, have difficulty with walking long distances, gait patterns may be abnormal, muscle could be wasting, and/or there could be a decrease in upright balance. It would be a disservice to the patient not to assess and address these possible post-TCC findings.

For starters, muscle wasting or atrophy occurs when the muscle is not being used. Think about another adage here: Use it or lose it. When applying TCC, the ankle is locked in a neutral position, therefore limiting the amount of available range of motion (ROM). If we consider that someone may be treated with TCC up to approximately 79 days, muscle wasting, especially in the gastrocnemius, may be observed. This is evident when we remove the cast and see a leg girth difference as well as marked weakness. If a joint such as the ankle is kept immobile, there’s a tendency to develop a contracture, such as in the Achilles. Remember that diabetes can lead to stiffness and tendon damage due to glycation of collagen. Decreased movement and contractures can also lead to a decrease in ROM. A joint with decreased ROM compounded with muscle/tendon stiffness may also increase unwanted plantar pressures during the gait cycle. When muscle atrophy, joint stiffness, and decreased ROM are combined with older age, the “perfect storm” for balance dysfunction is the result. We are aware that medications and orthostatic hypotension may cause seniors to lose their balance, among other causes. Patients living with diabetes may also experience nerve damage, which will affect balance, not to mention cause muscle atrophy. Any combination of these will decrease the patient’s activity level and quality of life.

How Is Balance Affected?

We utilize three systems to maintain our upright balance: vestibular (inner ear), proprioception (muscle, joints), and sensorimotor (vision). To prevent falling, we initiate the “ankle strategy” for small balance corrections. If this perturbation is too large, then the “hip strategy” will come into play. Think of the last few patients with diabetes you’ve treated—they most likely also have neuropathy and poor eyesight, thus leaving the vestibular system as the remaining source for their balance. This, in addition to age, increases risks for falling.

A Guide To Patient Assessment

All patients should be assessed for contractures, balance impairments, muscle atrophy, and any other underlying medical conditions. Treatments may include exercise, physical therapy, and/or surgery.

A gait analysis should be used to determine the root cause of any problems if an abnormal biomechanical issue exists. A therapist who specializes in vestibular rehab might be a worthy consult to address inner ear problems affecting balance. Specific muscle weakness should also be addressed to formulate a specific plan of care that will be carried over to a functional manner. A literature review revealed that exercise is supported for patients with diabetes because it increases their maximum rate of oxygen consumption, anaerobic threshold, time to anaerobic threshold, endurance, strength, metabolic control, emotional well-being, mental health, and vitality while decreasing metabolic syndrome risk factors, insulin requirement, and falls.8

Another study found that patients with diabetes who are educated through a foot-and-ankle exercise program experienced decreased joint stiffness and decreased peak plantar pressure during gait after only one month of intervention.8,9 Guidelines published by the United States government recommend that adults participate in 150 minutes of moderate or 75 minutes of vigorous aerobic activity per week. (Walking is considered to be a simple exercise that can be done at a vigorous pace.) These guidelines also recommend strengthening exercises twice per week. Patients should also be given a flexibility program to help keep their muscles and tendons from stiffening.

Conclusion

As we provide our diabetic population with appropriate offloading interventions, attention must be focused on potential side effects to keeping the extremity in a locked position. Recognizing late offloading effects, such as muscle atrophy, decreased ROM, decreased strength, and decreased balance can improve each patient’s functional status and safety while decreasing ulcer formation.

Frank Aviles Jr. is wound care service line director at Natchitoches (LA) Regional Medical Center; wound care and lymphedema instructor at the Academy of Lymphatic Studies, Sebastian, FL; physical therapy (PT)/wound care consultant at Louisiana Extended Care Hospital, Natchitoches; and PT/wound care consultant at Cane River Therapy Services LLC, Natchitoches.

 

Let's Be Frank
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Frank Aviles Jr., PT, CWS, FACCWS, CLT
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References

1. Fife CE, Carter MJ, Walker D. Why is it so hard to do the right thing in wound care? Wound Rep Reg. 2010; 18(2):154–158.
2. Fife CE, Carter MJ, Walker D, et al. Diabetic foot ulcer off-loading: The gap between evidence and practice. Data from the US Wound Registry. Adv Skin Wound Care. 2014; 27(7):310-6.
3. Shaw JE, His WL, Ulbrecht JS, et al. The mechanism of plantar unloading in total contact casts: Implications for design and clinical use. Foot Ankle Int. 1997; 18(12):809-17.
4. Lavery LA, Vela SA, Lavery DC, Quebedeaux TL. Total contact casts: Pressure reduction at ulcer sites and the effect on the contralateral foot. Arch Phys Med Rehabil. 1997; 78(11):1268-71.
5. Jaakola E, Weber A. Current Concepts in total contact casting for DFUs. Podiatry Today. 2014;27(4):20-27.
6. Greenhagen R. Complications of total contact casting. Podiatry Management. June/July 2012. Available at https://podiatrym.com/pdf/2013/6/Greenhagen612web.pdf .
7. Guyton GP. An analysis of iatrogenic complications from the total contact cast. Foot Ankle Int. 2005; 26(11):903-7.
8. Ritzline P. Foot and ankle exercise in patients with diabetes. Lower Extremity Review. January 2011. Available at https://lermagazine.com/article/foot-and-ankle-exercises-in-patients-with-diabetes
9. Biesenbach G, Bodlaj G, Sedlak M, et al. Exercise program for older patients with insulin-treated type 2 diabetes: long-term effects on metabolic control and BMI. Z Gerontol Geriatr. 2009;42(6):465-469.
10. Armstrong DG, Nguyen HC, Lavery LA, et al. Off-loading the diabetic foot wound. Diabetes Care. 2001; 24(6):1019-1022.
11. Brand PW. The insensitive foot (including leprosy). In Jahss M (ed.) Disorders of the Foot and Ankle. Saunders, Philadelphia, 1991, pp. 2170-2175.

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