QS59. Pulsed-release Dexamethasone-loaded Microspheres Mitigate Scar Contracture and Adhesions in Composite Tissue Burn Reconstruction

Abstract

Purpose: Soft-tissue loss after complex burns is devastating to quality of life, ability to work, and psychosocial well-being. These are disfiguring injuries requiring surgical management and are almost universally limited by contracture, adhesion, and soft-tissue deficit. We have previously described a fat-first, delayed-skin approach to complex burn reconstruction to treat the hypodermal deficit and improve soft tissue-mobility and deficits. Here we describe the use of timed- and pulse-release dexamethasone to augment this approach and mitigate contracture during skin-graft delay. Methods: Yorkshire swine received 16, 4x4 cm full-thickness burns. After 48 hours, eschar was removed to fascia. Wounds were stratified across untreated pigs to receive A) No Reconstruction, B) Skin-Only, C) Fat-Only, D) Immediate-Skin, Delayed-Fat, or E) Immediate-Fat, Delayed-Skin. Treatment pigs with Group E wounds then received either 1) Empty Microspheres or Dexamethasone as follows 2) Continuous/Sustained, 3) Immediate-Pulsed, 4) Delayed-Pulsed, or 5) Bimodal-Pulsed. At 8 weeks post-engraftment animals were sacrificed and all wounds were collected for photography, ultrasound, histology and serum studies. Results: Fat-first reconstruction minimizes adhesions soft-tissue deficits, however, is limited by rapid early contracture which was mitigated by the skin-first approach. Early dexamethasone blocks contracture, however, sustained dosing limited skin graft take. Pulsed-dosing was permissive of skin grafts in the drug elution nadir. Combination fat-first with pulsed-dexamethasone resulted in significant reduction in adhesion, soft-tissue deficit, and contracture vs. skin-first approaches. Conclusion: Here we demonstrate augmentation of a fat-first approach by timed-release dexamethasone to safely mitigate contracture, adhesion, and soft-tissue deficits vs. current reconstructive standards for complex burn wounds.