In Search Of An Offloading Standard
When it comes to multicenter clinical trials for various wound care modalities, it stands to reason all the elements of the study should be constant with the key variable being the modality or modalities one is comparing in order to determine the efficacy. However, what if one of those study elements (say offloading) is handled differently by the researchers involved in the study? Wouldn’t that detract from the validity of the results?
It’s a significant question raised in a recent Diabetes Care editorial, “Trials In Neuropathic Diabetic Foot Ulceration,” penned by David Armstrong, DPM and Andrew Boulton, MD, and a Diabetes Care article, “Activity Patterns Of Patients With Diabetic Foot Ulceration,” that they co-authored with others.
In the aforementioned prospective study of 20 patients with noninfected and nonischemic diabetic foot ulcers, the authors found the removable cast walker was only worn “during 28 percent of daily activity.” (See “Does Compliance Hamper The Efficacy Of Removable Cast Walkers?,” News and Trends, pg. 6.) They and others in the know postulate this lack of offloading compliance among those with noninfected, neuropathic diabetic foot ulcers may have played a role in “many trials” that had “less than impressive outcomes.”
So what is the best offloading modality when it comes to treating noninfected, neuropathic diabetic foot ulcers? Total contact casting (TCC) is the most proven offloading tool. In an oft-quoted study that compared TCC with a removable cast walker and a half-shoe, the researchers achieved an 89.5 percent healing rate with TCC whereas the removable cast walker netted a 65 percent healing rate and the half-shoe had a 58.3 percent healing rate.
While some recommend TCC as a “first-line therapy” for noninfected, neuropathic plantar foot wounds, the modality has not achieved broader mainstream use. It has an arduous learning curve, is widely perceived as time-consuming, and there is a lack of standardization when it comes to applying the cast and the materials that one uses for the cast.
Drs. Armstrong and Boulton have proposed an “instant TCC,” which would involve converting a removable cast walker into a non-removable device by wrapping it with plaster or a cohesive bandage. They believe the lighter device will help facilitate compliance, be easier to apply and reduce costs. However, others say this kind of device would thwart “the ability to check for infection on a daily basis and the ability to apply topical wound medications daily.”
In another recent Diabetes Care article, Ha Van, et. al., suggested the use of a non-removable, windowed fiberglass cast boot to treat noninfected, nonischemic plantar diabetic ulcers. Comparing the open-toed boot (which features a window cut over the ulcer and rubber heels) to an offloading shoe, the researchers found “excellent compliance” with the cast boot despite the fact that a history of prior non-compliance was among the patient selection criteria. However, they also noted that the cast boot was “bigger than the usual TCC” and took 60 to 90 minutes to create.
What about other alternatives? Removable casts or cam walkers with pressure off inserts are “becoming very popular,” says one DPM who sees a large number of diabetes patients. He also notes employing felted foam with unna boots and coban “works very well for offloading.”
Clearly, there is a need for future studies to evaluate different offloading modalities. However, for now, there needs to be a more unified front among the different researchers in multicenter wound care studies on what constitutes the offloading standard.