Evaluation of Removable and Irremovable Cast Walkers in the Healing of Diabetic Foot Wounds: A randomized controlled trial

In this randomized controlled trial, 50 patients were randomly assigned to one of two off-loading modalities. All patients provided written informed consent, and this study was approved by the University’s institutional review board. This included an RCW (Active Offloading Walker; Royce Medical, Camarillo, CA) or the same device wrapped entirely in a cohesive bandage (iTCC). The description of the application of this device has been previously described (11). The diagnosis of diabetes was made before enrollment and confirmed by either communication with primary care providers or by review of medical records. All patients had experienced the loss of protective sensation (>25 V) as measured with a vibration perception threshold meter (Xilas, San Antonio, TX) (12,13), at least one palpable foot pulse, and a neuropathic plantar diabetic foot ulcer corresponding to grade 1A (superficial, not extending to tendon, capsule, or bone, according to the University of Texas Diabetic Foot Wound Classification System) (14,15). Wound size was evaluated by measuring the maximum length by the maximum width. Patients with active infection; unable to walk without a wheelchair; with wounds in locations on the heel, rearfoot, or a location other than the plantar aspect of the foot; or with severe peripheral vascular disease (diagnosed by the criteria listed above based on the absence of both foot pulses on the affected extremity) were excluded. If patients had more than one plantar wound, the largest wound was used as the index ulcer for inclusion in this study.

Patients were randomly assigned through a computerized randomization schedule. Randomization was performed after the initial screening, with allocation provided to the treating clinician by a single study coordinator via telephone. All patients were instructed to use their devices at all times during ambulation. All patients were followed on a weekly basis for device inspection, wound care, and wound debridement. All wounds were surgically debrided as required on each visit. Patients were followed in this manner for 12 weeks or until wound healing (defined as complete epithelialization), whichever came first.

We evaluated the influence of the effect of continuous variables on healing in general with a Mann-Whitney U test. Dichotomous variables were evaluated with a χ² test with odds ratio (OR) and 95% CI. To evaluate the healing characteristics of each device as a function of weeks of therapy and mean time to closure among patients healing within the 12-week study period, we used a Kaplan-Meier life table analysis (log-rank test). With the above analyses, a difference of 40% between groups could be detected with a sample size of 18 per group, yielding a power exceeding 80%. For all analyses, we used an α value of 0.05. Of an initial enrollment pool of 50 patients, 4 failed to complete the course of study. Reasons for this included discomfort/weight of the device (one RCW, one iTCC) or failure to return for follow-up appointments or data collection visits (two RCW). These patients were considered treatment failures (nonhealers) for the purpose of the intent-to-treat analysis.

Descriptive characteristics of the populations are listed in Table 1. There were no significant differences in any of the descriptive characteristics evaluated. However, wound size was nearly greater in the iTCC group (2.7 ± 1.3 vs. 2.0 ± 1.1 cm², P = 0.07).

Within the intent-to-treat population, a significantly higher proportion of patients healed at 12 weeks in the iTCC group than in the RCW group (82.6%/19 patients vs. 51.9%/14 patients, P = 0.02, OR 1.8 [95% CI 1.1−2.9]). This was also true for the 46 patients who completed the entire course of evaluation (86.4%/19 patients vs. 58.3%/14 patients, P = 0.04, 1.5 [1.0−2.2]). There was also a significant difference in cumulative wound survival at 12 weeks between patients treated with an iTCC versus an RCW (P = 0.003). These data are illustrated in Fig. 1. Of the patients that healed during the period of evaluation, those treated with an iTCC healed significantly sooner (41.6 ± 18.7 vs. 58.0 ± 15.2 days, P = 0.02).

There were no falls, device-related ulcerations, or hospitalizations reported during the course of study. However, significantly more patients using the iTCC presented with at least one episode of periwound maceration than did those using the RCW (68.2%/15 patients vs. 37.5%/9 patients, P = 0.04, OR 1.8 [95% CI 1.0−3.3]). With the numbers available for study, there was no significant difference between the proportion of patients requiring antibiotics to treat a soft tissue infection during the course of treatment (27.3%/6 patients iTCC vs. 41.7%/10 patients RCW, P = 0.4).

TCCs have been espoused to be one of the most effective treatments in healing neuropathic ulcers in people with diabetes. Despite evidence that several brands of RCWs, such as the Active Offloading Walker, Aircast (Aircast, Summit, NJ), and Conformer Boot (Bledsoe, Dallas, TX), may reduce peak foot pressure as effectively as a TCC (8,14,15), they have not been as effective as TCCs in clinical practice (9,16).

In a randomized trial comparing RCWs and TCCs, 65% of ulcers healed in the RCW group (using an Aircast RCW) and 90% of ulcers healed in the TCC group. Our results with the Active Offloading Walker were similar to results with the Aircast RCW. When the Active Offloading Walker was modified, the iTCC study group demonstrated a healing rate similar (86% in 12 weeks) to that in previous studies that used a traditional TCC as the off-loading treatment. There is a large body of literature that reports consistently high rates of healing (73–100%) with TCCs (Table 2) (3,4,6,7,9,17–26). However, because TCCs are technically difficult to use and time consuming to place, they are not widely used in most clinics worldwide. In essence, in most communities they remain an ideal gold standard of treatment and not the true community standard. Instead many clinicians choose to compromise and use less demanding and often less effective pressure off-loading therapies.

One of the most attractive features of the genre of RCW products is that they are easy to apply and safe to use; thus, clinicians with a wide range of experience use an effective pressure-reducing product. Many clinicians and therapists who would not be comfortable applying a TCC can readily use most RCWs. The unfortunate downside is that patients can also remove the product. Patient adherence to use of removable devices seems to be poor. By implanting a computerized activity monitor in patients’ RCWs, we previously demonstrated that these off-loading devices are used for less than one- third of the total activity taken per day (10). By applying a simple wrap around a traditional RCW, both the proportion and rate of wound healing was substantially improved by preventing patients from removing the device. Like most therapies, the iTCC requires thoughtful patient selection and diligent monitoring, but our initial clinical results are thought provoking and may be a catalyst for modifying our current clinical approach.

This work was supported by U.S. Department of Veterans Affairs, Health Services Research and Development Award IIR 20-059 and the Rehabilitation Research and Development Merit Award A2150RC.