Anatomical study of the medial sural artery perforator flap and its application in the reconstruction of infected defects.

The medial sural artery perforator (MSAP) flap is widely used clinically for infected soft tissue defect repair and reconstruction due to its numerous advantages. However, the safe boundary of it was limited. The aim of this study was to explore the causes underlying the limited boundary of the MSAP flap via an anatomical study and to present the results of our clinical utilization of this flap for the reconstruction of infected defects. Five fresh lower limb specimens were perfused and then radiographed. From April 2023 to July 2025, 7 MSAP flaps were elevated in 7 patients for the reconstruction of infected soft-tissue defects over the knee, middle and distal leg, and heel. The reconstruction outcomes were documented and evaluated. The arteriography revealed that the anastomoses between adjacent medial sural artery perforators, as well as those between medial sural artery perforators and surrounding perforators, were choke anastomoses. All of the 7 flaps survived completely without any indications of arterial insufficiency or venous congestion. No clinical signs of persistent or recurrent infection, wound dehiscence, or flap necrosis were detected during the available follow - up period. These findings demonstrate that the MSAP flap can be effectively utilized to repair small - and medium - sized infected defects on the extremities. The possible factors influencing the limited harvestable boundary of this flap are that all adjacent perforators are anastomosed through choke vessels.