Cadaveric anatomical study of anterior and posterior ankle arthroscopic portals in ankle plantarflexion and dorsiflexion positions

Abstract

Category: Arthroscopy Introduction/Purpose: Arthroscopy of the foot and ankle, which is minimally invasive technique, is able to be used in the treatment of various foot and ankle pathologies. However, complications after anterior or posterior ankle arthroscopies have been described, such as neurovascular structures injury around portals. On the other hand, plantarflexion and dorsiflexion of the ankle joint leads movement of the neurovascular structures. However, there were a few reports about the change of the distance between each portal and nerves or vessels during motion of the ankle. The purpose of this study was to evaluate the distance between each anterior or posterior portal and neurovascular structures, to elucidate the change of the distance between each portal and neurovascular structures in ankle plantarflexion and dorsiflexion positions. Methods: Six feet of 6 fresh cadavers (3 males and 3 females) were enrolled in this study. The mean age was 81.5 years. Standard antero-lateral (AL), antero-medial (AM), postero-lateral (PL) and postero-medial (PM) portals were identified using needles. Skin was dissected from the underlying soft tissue to visualize neurovascular structures clearly as little as possible. The distances were assessed in ankle plantarflexion position and dorsiflexion position, from AL portal to superficial peroneal nerve (SPN), from AM portal to saphenous nerve (SpN), great saphenous vein (SpV), from PL portal to sural nerve (SN) and lesser SpV, and from PM portal to flexor hallux longus, posterior tibial artery PTA and tibial nerve (TN). Results: SPN was the closest structure to any of the anterior portals (3.2 /8.3 mm in ankle plantarflexion position and 5.2 /10.8 mm in ankle dorsiflexion position from AL portal as Fig.1 was showing), followed by SpN in anterior ankle arthroscopy. Distances from SPN to AL portal, and from SpN and great SpV to AM portal increased with ankle dorsiflexion and decreased with plantarflexion. SN was the closest structure to any of the posterior portals (10.4 mm in ankle plantarflexion position and 8.5 mm in ankle dorsiflexion position from PL portal), followed by lesser SpV in posterior ankle arthroscopy. Distances from SN, SpN and lesser SpV to PL portal, and from FHL, PTA and TN to PM portal increased with ankle plantarflexion and decreased with dorsiflexion. Conclusion: Results of this study showed the distances from each anterior or posterior arthroscopic portal to neurovascular structures, and elucidated the change of the distances between each portal and neurovascular structures in ankle plantarflexion and dorsiflexion positons in ankle plantarflexion and dorsiflexion positions. The ankle dorsiflexion position for the standard AL and AM portals placement and the ankle plantarflexion position for PL and PM portals placement might be recommended. Results of this study might be useful to prevent injury to the neurovascular structures during anterior or posterior ankle arthroscopy.