Coverage of complex pararectal pelvic defects: role of the free myocutaneous musculus vastus lateralis flap

Abstract

In the event of an advanced rectal carcinoma, an evisceration with rectal amputation may become necessary. The resulting defects, due to their extent, depth, or local tissue damage from previous surgeries and radiation, can in many cases only be closed through free microvascular tissue transfer. In this case series, we demonstrate the successful combination of a musculocutaneous musculus vastus lateralis flap (MVL) with a direct connection to the superior gluteal artery. Over a 47-month period, we retrospectively examined 11 cases of patients with dorsal pelvic defects after evisceration and rectal amputation that could not be closed using local or regional means. In cases of extensive defects with deep pararectal wound cavities, all these patients underwent defect coverage through a free myocutaneous MVL flap with a direct vascular anastomosis to the superior gluteal vessels. The mean defect size was 290.0 cm² (SD: 131.2; range: 200-600 cm²). The mean defect depth was 10.5 cm, necessitating MVL flap reconstruction with an average size of 336.3 cm². Three operative revisions were required due to postoperative bleeding. There were no arterial or venous thromboses, and no flap loss occurred. Only one necrosis of a distal flap tip was observed, which could be corrected secondarily by direct suturing. The case-mix evaluation yielded an average value of 24.251 (SD: 21.699; range: 7.036-65.748) points, emphasizing the complexity of the cases. Our results indicate that a free microvascular MVL flap is a viable therapeutic option for pararectal defects that cannot be closed by local or regional methods. The superior gluteal artery proves to be a safe and sufficient vascular connection. In combination, even extensive defects can be successfully closed.