Evidence Corner: Biologic Dressings for Foot Ulcers
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Healthy feet help us preserve our independence, earn our livelihood, and participate actively in our social environment. A foot ulcer can isolate and depress the individual who suffers it while increasing risk of amputation, infection, or mortality. Healing foot ulcers quickly helps limit the costs and burden of care and keeps patients active as contributing members of family and society. Most foot ulcers will decrease in area by at least 50% in 4 weeks and proceed to complete healing by 12 weeks1,2 when their growth factor-rich, enzyme-laden fluid is sealed over the wound, cause(s) of injury stopped, and devitalized tissue removed.1
Foot ulcers unresponsive to this best standard of care may need further impetus to heal. Biologic skin substitutes (BSS) containing different types of living or dead cells or matrices have been explored as interventions to speed foot ulcer healing. In a large randomized controlled trial (RCT) involving patients with full-thickness plantar diabetic foot ulcers (DFU), 56% of 112 subjects healed in 12 weeks when dressed with a BSS containing living allogeneic fibroblasts and keratinocytes, compared to 39% of the 96 subjects randomized to receive a porous wound contact layer covered by a saline gauze dressing,3 a dubious standard of care.4-6 Interpretation of biologic dressing results has been clouded by use of removable offloading devices which delays healing7 and differences in test and control dressings’ capacity to seal moisture over the wound to permit moist healing.5,6 The 2 recent studies reviewed below identify important variables to control and to study in clarifying effects of foot ulcer treatment with BSS.
Living Cells Improve Foot Ulcer Healing
Reference: Felder JM III, Goyal SS, Attinger CE. A systematic review of skin substitutes for foot ulcers. Plast Reconstr Surg. 2012;130(1):145-164.
Rationale: The clinical and economic challenges of foot ulcers have been addressed in recent years by increasing numbers of biologically derived artificial skin substitutes as tissue culture technology progressed.
Objective: Inform decisions about foot ulcer care with a systematic review describing the quality and quantity of evidence of safety and efficacy of BSS in treatment of chronic foot ulcers of all types.
Methods: PubMed, MEDLINE, EBSCO, EMBASE, and the Cochrane Central Register of Controlled Trials were searched for controlled or prospective comparative cohort studies and systematic reviews reporting outcomes of human controlled clinical trials including non-traumatic foot ulcers of any etiology treated with any form of BSS. Derivative references and trials known to experts were included. Three reviewers wrote structured abstracts of each reference, including standardized entries of study citation, design, procedures, and outcomes reported. Evidence quality was rated on the Jadad scale based on blinding, randomization, and subject withdrawal information.
Results: Of 271 studies identified, 15 RCTs and 1 prospective comparative cohort study qualified for inclusion in the systematic review: 12 studies on DFUs, 3 on venous ulcers, and 1 on foot ulcers of unspecified etiology. Six studies of a neonatal fibroblast- and-keratinocyte-populated BSS on a bovine Type I collagen substrate supported its safety and effectiveness on DFUs and venous ulcers. Four studies of a fibroblast-derived BSS on a polyglactin substrate reported it safe and effective on DFUs only if the fibroblasts were metabolically active. Three studies reported more DFUs healed when dressed with an acellular dermal layer derived from human cadaver skin than control-treated DFUs.