Evaluation of Effects of Conformable Bovine Collagen on Diabetic Foot Wounds Requiring Surgical Reconstruction

Introduction:
Diabetic foot ulcers represent a major cause of morbidity in diabetic patients, with lifetime risk of foot ulceration often greater than 30%, and are the underlying etiology of the majority of amputations performed in the US unrelated to trauma.1,2 Many adjunctive products are available to assist in healing, and a cornerstone of surgical management of DFUs have been products made of bovine collagen, which have been found in prior investigations to enhance wound healing through its effects on modulating and attracting local inflammatory cells, acting as a scaffold for cellular processes,  and cultivating extracellular matrix through mitigating the buildup ECM degrading matrix metalloproteinases.3 However, many topical collagens come in pre-formed sheets. In this study we investigate a flowable bovine collagen matrix intended to better conform to irregular wound bed surfaces in DFUs.
 

Methods:
This single arm, open label, single institution, historic comparative quality assessment enrolled 4 patients with DFUs appropriate for OR debridement and placement of cellular and/or tissue-based products (CTPs), for application of flowable bovine collagen matrix in the OR. Patients followed up for 4 weeks with weekly visits. Re-application of the product was performed, if necessary, in the clinic setting. Primary endpoints were treatment tolerance and lack of wound infection; secondary endpoints included percentage of wound closure at 4 weeks, compliance, and adverse events.
 

Results:
Patient wound sizes ranged from .4cm2 to 10cm2. All patients participating in the study had initial application of the flowable bovine collagen matrix in the OR after appropriate debridement, and all patients tolerated application without issue. No new wound infections were reported during the 4 week follow up. There were 5 total wounds treated, as one patient had the product additionally applied to a post-op TMA wound on clinic follow up. Average wound size decreased by 28.6%. The studied generation of product had a low viscosity which was more difficult to apply and maintain in contact with shallow wound beds, even with offloading. The product also tended to stick to the initial non-stick secondary dressing of knitted cellulose acetate impregnated with petroleum emulsion, and the dressing was changed to a transparent film dressing with more success.
 

Conclusions:
Flowable matrices represent an efficacious delivery method for bovine collagen products intended to accelerate wound healing in diabetic foot ulcers. Although this was a limited study, the initial results—particularly with deeper wound beds—were encouraging, with good tolerance of the product, no infections or adverse events, and an overall average decrease in wound size of 28.6% over 4 weeks of follow up. We look forward to the improved viscosity addressed in the next generation of this product as well as further investigating the best secondary dressing for securing the product in the wound bed.

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