Sural Nerve Splitting in Reverse Sural Artery Perforator Flap: Anatomical Study in 40 Cadaver Legs

Background: The reverse sural artery perforator flap has been widely used in reconstruction of the lower extremity. However, along with the high rate of flap necrosis, sural nerve injury is one of the most frequent complications. This cadaveric study investigated a simple sural nerve preservation technique during reverse sural artery perforator flap surgery. Methods: Cadaver dissection was performed on 40 cadaver lower legs, to investigate the pattern of sural nerve distribution. The points where the lateral and medial sural cutaneous nerves penetrate the deep fascia were measured. The converging point of these nerves into the sural nerve was also recorded. Furthermore, the sural nerve was split until no tethering was observed, to simulate the sural nerve-sparing reverse sural artery perforator flap. Results: Twenty-nine legs (72.5 percent) showed the lateral and medial sural cutaneous nerves converging to become the sural nerve (combined pattern); seven (17.5 percent) and four legs (10.0 percent) demonstrated the diminished and parallel types, respectively. The distances between the lateral malleolus and the fascia-penetrating point of the lateral and medial sural cutaneous nerves were 29.9 +/- 3.3 cm and 18.8 +/- 5.6 cm, respectively. In the combined type, the point of convergence was 13.6 +/- 4.2 cm from the lateral malleolus. Nerve splitting was successfully performed in all combined cases, without injuring the nerve fascicles. Conclusions: The medial sural cutaneous nerve enters the deep fascia significantly more distally than does the lateral sural cutaneous nerve. Furthermore, using nerve splitting, the medial sural cutaneous nerve can be kept intact during reverse sural artery perforator flap surgery.