Evolving Concepts of Keystone Perforator Island Flaps (KPIF): Principles of Perforator Anatomy, Design Modifications, and Extended Clinical Applications

Background: Keystone flaps have demonstrated growing clinical applications in reconstructive surgery in the past decade. This article highlights flap modifications and their versatility for clinical applications and management of complex defects. Methods: A retrospective chart review was conducted of consecutive patients undergoing keystone flap reconstruction at the authors' institution from January of 2012 to December of 2014. Patient demographics, indications, and operative and postoperative details were abstracted. Results: Forty-two keystone flaps were performed in 36 patients. Indications included malignant melanoma (n = 14), soft-tissue sarcoma (n = 12), benign pathologic conditions (e.g., exposed hardware, enterocutaneous fistula, tissue necrosis) (n = 6), and nonmelanoma skin cancer (n = 4). Twenty-eight percent received neoadjuvant irradiation, and 70 percent of these were for sarcoma. Locoregional adjunct flaps were performed in eight patients. The deep fascia was nearly completely in a circumferential manner in 18 of 36 patients (50 percent), in 92 percent of the sarcoma reconstructions, and located mainly in the lower extremity. Average defect size was 215 cm² (range, 4 to 1000 cm²). Average defect size was 474 cm² and 35.8 cm² after sarcoma and malignant melanoma resection, respectively. Average flap size was 344 cm² (range, 5 to 1350 cm²). Ninety percent of cases had flap sizes exceeding the traditional 1:1 ratio. There was no flap loss or partial necrosis. Mean time to mobilization was 1.8 days, and mean hospital length of stay was 6.8 days. Conclusions: Keystone flaps offer an excellent versatile tool for reconstructive surgeons. Fundamental principles behind the vascular basis of the keystone flap and its modifications permit their greater utility in complex wounds in the settings of large oncologic resections, irradiation, and trauma.