Lateral supramalleolar flap: Is it based on perforator of peroneal/anterior tibial artery; A cross-sectional study at tertiary care centre

Background: To determine the anatomical basis of supramalleolar flap; retrograde versus antegrade and its clinical outcome based on the vascular pattern. Methods: This analytic cross-sectional study was conducted at a tertiary care hospital in Karachi, Pakistan. Patients who underwent coverage of soft tissue defects around the foot and ankle with supramalleolar flaps were included. Data collection was through medical records including demographic parameters, mechanism of injury, per-operative findings of perforator origin, and patient interviewing for final assessment. Patients with peripheral vascular disease, unavailability of skin, and radiation injuries were excluded. All analysis was done using SPSS version 25.0. Results: 49 patients were included in the study from May 1999 to December 2020. The male to female ratio was 37:12. The cause of soft tissue defects was trauma in 9 (38.7%) followed by Infection in 16 (32.6%) and Blast injury in 5 cases (10.2%). The maximum flap size harvested was 20 x 8 cm. In 19 cases the peroneal artery perforator was absent and the flap was based on the perforator of an anterolateral malleolar branch (antegrade) while the remaining 30 flaps were based on the perforator of the peroneal artery (retrograde). Overall, the flap survival rate was 98%; as 1 case had partial necrosis and required skin grafting. However, there were 9 minor complications. In 8 patients, the flap was rotated as a 'delay flap'. All patients had satisfactory functional outcomes without significant morbidity of the donor site. Conclusion: The lateral supramalleolar flap provided coverage to almost all regions of the foot and ankle with a cosmetically acceptable donor and recipient site. There were no problems with shoe wear, as only 2 patients required defatting for cosmetic reasons. Microvascular expertise was required for a predictable outcome.