forefoot ulceration? Diabetes Metab Res Rev 2004;20:S37, S40. 17. Mueller MJ, Sinacore DR, Hastings MK, Strube MJ, Johnson JE. Effect of Achilles tendon lengthen- ing on neuropathic plantar ulcers. A randomized clinical trial. J Bone Joint Surg Am 2003;85A:1436, 1445.
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25 Conventional Offloading and Activity Monitoring Lawrence A. Lavery and Douglas P. Murdoch
Ulcers in persons with diabetes and neuropathy often develop as a result of a moderate or high level of mechanical stress on the sole of the foot.
The magnitude, duration, rate and direction of mechanical stress are pivotal factors in repetitive injuries.
The number of times a day the foot is exposed to these forces or the number of steps the patient takes on a daily basis is the other part of the equation.
Until recently, pressure at the site of foot ulceration has been the principal focus of much of the clinical and laboratory research, because there were tools readily available to measure foot pressures.
Activity evaluation has only recently received attention in the literature, while other factors such as shear still do not have adequate clinical equipment for routine assessment.
Reduction of pressure and shear forces on the foot may be the single most important and most neglected aspect of neuropathic ulceration treatment.
Offloading therapy is a pivotal part of the treatment plan for diabetic foot ulcers.
The goal is to reduce or eliminate pressure at the ulcer while keeping the patient walking.1,2 There are a variety of methods available to protect the foot from abnormal pressures.
The selection of an offloading treatment must be tailored to the strength, activity, postural stability and co-morbidities of the patient.
However, in most cases, the more restrictive the offloading strategy, the better the healing environment.3 The patient and clinician must appreciate that foot ulcers are usually the result of repetitive injury and that every unprotected step is literally tearing the wound apart.
Without addressing this important component of the causal pathway, the wound will continue to be re-injured, and in many instances, it will remain open.
Obviously, patients prefer something that is light and easy to walk with, but in reality, the most effective treatment strategy requires a device that will severely disrupt normal activity for 6, 8 weeks.
Who would think of allowing a patient with a tibia or ankle fracture to walk without proper immobilisation?
Yet, we often provide ineffective but convenient forms of offloading therapies in patients at risk of amputation.
The total contact cast (TCC) is considered the ‘ideal’ gold standard to heal diabetic foot ulcers.4−10 The strength of this technique is that the extremity is protected every minute of the day.
It is one of the techniques most often reported in the medical literature to facilitate wound healing in the insensate extremity (Table 25.1).
Across centres, in descriptive cohort studies and randomised clinical trials, TCCs heal about 90% of foot ulcers.
The average healing time ranges from 6 to 8 weeks.
The consistency and high rate of wound healing with TCCs is much
The Foot in Diabetes, 4th Edition. Edited by Andrew J.M. Boulton, Peter R. Cavanagh and Gerry Rayman. C 2006 John Wiley & Sons, Ltd. ISBN: 0-470-01504-7
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Table 25.1 Healing times with total contact casts
Offloading Type of modality Mean healing time Type of study % Healed wound References
TCC Forefoot ulcers: Retrospective 90 Wagner Myerson et al.11 30 days cohort‡ 1, 2 Rearfoot, midfoot ulcers: 63 days TCC Forefoot ulcers: Retrospective Not reported Wagner Walker et al.4 31 days cohort‡ 1, 2, 3 Rearfoot, midfoot ulcers: 42 days TCC 40 days Retrospective 94 Wagner Birke5 cohort‡ 1, 2 TCC 38 days Retrospective 73 Wagner Helm et al.6 cohort‡ 1, 2, 3 TCC 44 days Retrospective 82 Wagner Sinacore et al.7 cohort‡ 1, 2 TCC Midfoot ulcers: Retrospective 100 Wagner Lavery et al.8 28 days cohort‡ 1, 2 TCC 34 days RCT† 90 UT 1A Armstrong et al.9 RCW 50 days 65 Half shoe 61 days 58 TCC 85 days RCT† 90 Wagner Mueller et al.10 Shoe insole 65 days 32 1, 2 RCW 42 days RCT 83 UT 1A, Armstrong and ITCC 58 days 52 2A Lavery12
TCC, total contact cast; RCT, randomised clinical trial; UT, University of Texas; RCW, removable cast walker; ITCC, instant total contact cast. ‡ Percentage healed no specified time. * Percentage healed in 30 days. † Percentage healed in 12 weeks. ‡ Percentage healed in 10 weeks.
better than what has been reported in randomised clinical trials with ‘advanced technologies’ such as bioengineered tissue, growth factors and electrical stimulation.
These types of advanced technologies report ulcer healing in 30, 65% of patients in 12- to 20-week studies.13−18 One of the most criticised design elements of ‘advanced wound therapies’ studies is their lack of a rigorous form of offloading as part of standard therapy.
Most studies use a therapeutic shoe or healing sandal as the standard offloading technique, ensuring that their ‘control group’ will have suboptimal healing rates.
There is no published work that compares an advanced wound therapy product with aggressive offloading with a TCC.
TCCs contrast with traditional fracture casts in several important ways.
TCCs usually have very little cast padding.
Felt padding is applied to the anterior crest of the tibia and over the medial and lateral prominences of the ankle bones (Figure 25.1).
These are often sites of pressure, friction and iatrogenic ulceration, even when a well-moulded TCC is expertly applied.
The toes are padded with foam and covered with cast material in order to protect them from injury.
Well-moulded plaster cast material is the first layer used over the cast padding.
It is applied to conform to the contour of the foot and ankle, then actively massaged and moulded
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Figure 25.1 (a,b,c) Total contact cast application demonstrating padding over the toes and prominences of the ankle bones. The first layer of plaster is well moulded to conform to the foot and ankle
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Figure 25.1 (Continued )
to achieve total contact with the surfaces of the lower extremity.
This reduces motion as the cast dries and cast padding compresses.
Fibreglass cast material is then applied as an outer layer, so that the patient can walk on the cast within 30 min.
Classically, a 3-mm-thick board is incorporated into the fibreglass and a cast heel is positioned in the plantar central aspect of foot.
This helps to further reduce pressure on the foot during ambulation.
TCCs are usually changed every week or two.
Ideally, they are initially applied and scheduled to be changed in the morning, to reduce the severity of lower extremity swelling.
If an extremity is severely swollen, a compression dressing should be applied for 2, 5 days before a cast is applied.
Walkers, canes or crutches should be used especially in older and obese patients or in patients with postural instability.
TCCs are often thought to be contraindicated in patients with infection and severe peripheral vascular disease (PVD).
In fact, most published clinical studies of wound-healing therapies sys- tematically eliminated these patients from consideration.
It is therefore difficult to extrapolate much of the existing data to patients with neuroischaemic wounds or wounds with infection.
Nabuurs-Franssen and colleagues reported clinical outcomes of TCC therapy in a prospective cohort of 98 patients with neuropathy (100%), PVD (44%) and infection (29%).
As in other studies, 90% of patients without infection or ischaemia healed, and 87% of infected ulcers healed.
In patients with vascular impairment, 69% healed.
However, in patients with PVD and infection, only 36% healed.19 TCCs are advantageous for several reasons.
They allow complete rest of the foot, even though the patient can be mobile and active during the therapy.
They help control oedema that can impede healing and protect the foot from trauma and infection.20 Perhaps, most importantly,