Technique for Fabrication of an “Instant Total-Contact Cast” for Treatment of Neuropathic Diabetic Foot Ulcers

Abstract

Addressing pressure reduction in the treatment of diabetic foot wounds is a critical component of therapy. The total-contact cast has proven to be the gold standard of treatment because of its ability to reduce pressure and facilitate patient adherence to the off-loading regimen. Removable cast walkers have proven to be as effective as total-contact casts in pressure reduction, but this has not translated into equivalent time to healing. A simple technique to convert the removable cast walker into a device that is not as easily detached from the lower extremity, thereby encouraging the use of this device over a 24-hour period, is presented in this article. The procedure involves wrapping the cast walker with cohesive bandage or plaster of Paris. In the authors’ opinion, this technique addresses many of the disadvantages of the total-contact cast, resulting in an adequate compromise in this aspect of care.

Total-contact casting has been called the gold standard modality in off-loading the diabetic foot.[1] Without question, it is as effective as any other existing therapeutic treatment in off-loading the foot.[2] Armstrong et al [3] recently published results of the first randomized controlled trial comparing the total-contact cast with two other readily available and popular devices, removable cast walkers and half-shoes, in the healing of ulcers. The authors found that the proportion of patients healed using the total-contact cast was significantly higher than the proportions healed using the other devices. The researchers also found similar activity levels in patients wearing a total-contact cast and those wearing a removable cast walker. Previous studies have suggested that certain removable cast walkers, including the one reviewed in the above-mentioned study, reduce pressure in the laboratory approximately as well as the total-contact cast.[2,4] One may, therefore, rightly question why a higher proportion of patients healed in the total-contact cast than in the removable cast walker. It could be argued that pressure reduction is not important, and that some other characteristic of the cast promotes healing better than other modalities, or that patients remove their removable cast walker and walk without protective footwear. Certainly, numerous studies have suggested that plantar pressure is an important aspect of the pathogenesis and healing of diabetic foot wounds.[5-10] The literature includes two descriptive reports evaluating compliance with footwear off-loading modalities in patients at high risk for lower-extremity amputation. Knowles and Boulton [11] reported that only 22% of 50 patients at risk for ulceration regularly wore their protective shoes. Armstrong et al [12] evaluated a similar patient population using a novel, computerized, Internet-based continuous activity monitor. In this study, only 15% of the patients indicated that they wore their shoes at home, where they conducted more than 50% of their daily activity. On the basis of these results and the clinical experience of the current authors with patients with profound neuropathy, it is suggested that the easier a device is to remove, the more difficult it may be to reapply.

The removable cast walker is a very attractive off-loading device. It is probably less expensive in terms of time and material costs than the repeated application of total-contact casts. It requires very little training to apply and is reusable. In the authors’ experience, the removable cast walker is better tolerated than a total-contact cast by patients and preferred by most clinicians. It could be argued that the least attractive attribute of the removable cast walker is its ease of removal. For several years, the authors have suggested to various manufacturers of these devices that they develop a system that could lock in place, thereby reducing the risk of loosening or early removal. Unfortunately, there appears to be no movement on behalf of the manufacturers to modify these devices. Therefore, the current authors present a technique for rapidly converting a removable cast walker to one that is less easily removed.

Any removable cast walker can be used for this technique. The authors generally prefer the Aircast removable cast walker (Aircast Inc, Summit, New Jersey) or DH Pressure Relief Walker (Centec Orthopaedics, Camarillo, California), as these two devices have generally excellent off-loading characteristics.[2] The devices should be applied in the recommended manner. If warranted, cast padding can be applied to the patient’s leg. Two layers of 4-inch cohesive bandage or plaster of Paris should be applied around the removable cast walker (Fig. 1, Fig. 2, Fig. 3 and Fig. 4). If plaster of Paris is used, the device should be covered with 4-inch cohesive bandage or a stockinet before the plaster of Paris is applied to prevent soiling the removable cast walker and facilitate its reuse. Care should be taken not to extend casting material or bandage proximal to the foam padding of the walker to avoid skin irritation or impingement of the common peroneal nerve as it courses near the fibular head. The digits can be padded with self-adhesive foam (Reston Self-Adhering Foam, 3M, St Paul, Minnesota) if the clinician wants to cover the toes to prevent foreign objects from entering the cast walker. The clinician may then consider dispensing a cast protector to allow the patient to shower more easily. Alternatively, the patient may use a large, thick trash bag to protect the cast walker.

Conclusion

A simple, rapid technique to convert a removable cast walker into a device that is less easily removed has been presented. Rather than being punitive, this approach emphasizes the clinician’s understanding of the importance of aggressive off-loading of diabetic foot wounds. The authors eagerly await a randomized trial comparing the use of this modification with a standard total-contact cast.