Revisit of flap factors relating to partial necrosis of distally based sural flaps: an analysis of 435 cases in a single center

Partial necrosis is an ongoing topic in regard to flap complications of the distally based sural (DBS) flap However, the factors influencing partial necrosis of the flap remain in debate. The aim of the present study is to further illuminate the flap-related risk factors and the effects of several technical improvements. We retrospectively reviewed the data of 429 patients who underwent 435 DBS flaps between April 2001 and December 2019. The reconstruction outcomes, flap viability-related complications, and potential risk factors were compared between the survival group and partial necrosis group, as well as between group A (the procedures performed from April 2001 to March 2010) and group B (those from April 2010 to December 2019). Among the 435 flaps, 39 flaps (8.97%) exhibited partial necrosis. With the increase of the top edge of the flap, the partial necrosis rate increased significantly (P < 0.05). When the length-to-width ratio [LWR] of the flap was more than 5:1 or the total length of the flap (the length of the skin island plus the length of the adipofascial pedicle) was more than 20 cm, the partial necrosis rate increased significantly (P < 0.05). The partial necrosis rate in group B (5.86%, 15/256) was significantly lower than that in group A (13.41%, 24/179) (P = 0.007). The top edge of the flap is an essential indicator for predicting the prognosis of the DBS flap. When the total length of the flap is more than 20 cm or the LWR of the flap more than 5:1, the partial necrosis rate will increase significantly. Various technical modifications can lower the top edge of the flap and reduce the LWR of the flap and width of the skin island, and thus improve the flap survival effectively.