Unna Boot With Keystone Advancement Flap Leads to Excellent Outcomes for Lower Extremity Reconstruction

December 2021 | Volume 20 | Issue 12 | Original Article | 1308 | Copyright © December 2021

Published online November 30, 2021

Kristina Navrazhina BA, Tatyana A. Petukhova MD MS, Gulce Askin MPH, Kira Minkis MD PhD

Weill Cornell Medicine, New York, NY

Background: The reconstruction of lower extremity defects can be technically challenging. The keystone island perforator flap is a workhorse reconstructive option for difficult-to-repair regions, including the lower limb. The goal of this study is to evaluate outcomes using the keystone flap in combination with the zinc oxide compression dressing (Unna boot) for repair of lower extremity defects. Methods: We retrospectively evaluated 96 patients who underwent resection of malignancies or atypical neoplasms on the lower legs. A total of 114 defects were repaired with the keystone flap in combination with the Unna boot. Post-operative outcomes were assessed. Results: The combination of the keystone flap with postoperative Unna boot application led to excellent outcomes. There was no association between complication rates and patient co-morbidities. Conclusion: The combination of the keystone flap with the Unna boot is a safe and efficacious approach for reconstruction of lower extremity defects. J Drugs Dermatol. 2021;20(12):1308-1312. doi:10.36849/JDD.5915


Reconstruction of lower extremity defects following resection of cutaneous tumors is clinically and technically challenging.1 The lower limb has poor skin laxity and scarce subcutaneous tissue, which contributes to the complexity of surgical repair. Ambulation introduces sheer forces that hinder healing, while the increased hydrostatic forces exerted on the limb during movement promote hematoma and seroma formation.2 As a consequence of these factors, wounds on the lower limb have increased rates of infection and prolonged healing times.1,3,4

The anatomical and physiological factors predisposing patients to potential complications must be considered when selecting a repair method for defects of the lower extremities.1,5 The lower limb’s limited skin laxity and scarce subcutaneous tissue contributes to frequent dehiscence of primary linear closures.6,7 Alternatively, secondary intention healing (SIH) eliminates the risk of dehiscence, but carries an increased risk of bleeding, scar contracture and prolonged healing time.8 While multiple studies demonstrated the efficacy of split-thickness skin grafts (STSGs) and full-thickness skin grafts (FTSGs) in repairing lower extremity defects, grafts on the legs are associated with unfavorable outcomes, ranging from scarring to graft failure. Furthermore, poor vascularity in the lower third of the leg predisposes the region to higher complication rates.1,4,9 Ambulation increases hydrostatic and sheer forces, promoting seroma and hematoma formation, as well as jeopardizing graft imbibition and inosculation. Many physicians recommend immobilizing the affected limb for several days to decrease graft failure.8,10,11 However, even short post-operative immobilization can increase the risk of deep vein thrombosis, pulmonary embolism, and physical deconditioning, especially among the elderly or those with pre-existing co-morbidities.5,8,10,11 Additionally patient compliance with immobilization can be difficult to monitor and enforce in an outpatient setting. Despite various graft modifications, including delayed grafting and quilting the graft to the wound bed, lower extremity grafting remains challenging with high rates of graft failure.9,11-13

In recent years, the keystone flap has emerged as a versatile reconstructive approach for defects of varying sizes on the head and neck, trunk, and extremities.10,14,15 As described by Felix Behan, the keystone flap is a local fasciocutaneous flap that relies on perforator vessels for a robust vascular supply.3,14 The flap incorporates the musculocutaneous and fasciocutaneous perforators, promoting increased flap viability and survival, while minimizing tension and subsequent risk of dehiscence and necrosis, making it ideal for reconstruction in areas with low tissue laxity.6 Several keystone flap modifications have been described for regions requiring greater tissue recruitment, such as leaving the skin bridge intact to enhance flap survival and utilizing only the unilateral portion of the traditional keystone design,5,16 with several reports promoting the keystone flap for repair of lower extremity defects following dermatologic surgery.3,5,13,17,18