Introduction The Accessory Postero-Lateral (AccPL) portal has recently been described to improve the visualisation for the endoscopic debridement of Haglund's tubercle. The safety of using this portal has been considered previously for posterior ankle arthroscopy. We performed a study to determine the proximity of the AccPL portal to the sural nerve. Methods We compared the distances between AccPL and PL portals to the sural nerve in 17 cadaveric specimens. Results The AccPL portal was significantly closer (mean 12.0 mm, range 6–19 mm, SD = 3.64) to the sural nerve than the PL portal (mean 14.1 mm, range 11–18 mm, SD = 2.34) (t(16) = −2.34, p = 0.03). In two cases the sural nerve was in contact with the clip but on close inspection, the nerve had not been damaged in any of the specimens. Conclusions We conclude that the AccPL portal is a safe method to allow visualisation during endoscopic debridement of the Achilles tendon insertion. We also recommend that the portal is used for visualisation rather than instrumentation.