The course of the superficial peroneal nerve in relation to the ankle position: anatomical study with ankle arthroscopic implications

Abstract

Despite the fact that the superficial peroneal nerve is the only nerve in the human body that can be made visible; iatrogenic damage to this nerve is the most frequently reported complication in anterior ankle arthroscopy. One of the methods to visualize the nerve is combined ankle plantar flexion and inversion. In the majority of cases, the superficial peroneal nerve can be made visible. The portals for anterior ankle arthroscopy are however created with the ankle in the neutral or slightly dorsiflexed position and not in combined plantar flexion and inversion. The purpose of this study was to undertake an anatomical study to the course of the superficial peroneal nerve in different positions of the foot and ankle. We hypothesize that the anatomical localization of the superficial peroneal nerve changes with different foot and ankle positions. In ten fresh frozen ankle specimens, a window, only affecting the skin, was made at the level of the anterolateral portal for anterior ankle arthroscopy in order to directly visualize the superficial peroneal nerve, or if divided, its terminal branches. Nerve movement was assessed from combined 10 degrees plantar flexion and inversion to 5 degrees dorsiflexion, standardized by the Telos stress device. Also for the 4th toe flexion, flexion of all the toes and for skin tensioning possible nerve movement was determined. The mean superficial peroneal nerve movement was 2.4 mm to the lateral side when the ankle was moved from 10 degrees plantar flexion and inversion to the neutral ankle position and 3.6 mm to the lateral side from 10 degrees plantar flexion and inversion to 5 degrees dorsiflexion. Both displacements were significant (P < 0.01). The nerve consistently moves lateral when the ankle is manoeuvred from combined plantar flexion and inversion to the neutral or dorsiflexed position. If visible, it is therefore advised to create the anterolateral portal medial from the preoperative marking, in order to prevent iatrogenic damage to the superficial peroneal nerve.

Fig. 1

Transverse section at the level of the ankle joint. a. Anatomical relations of the anterolateral portal. b. Anatomical relations of the anteromedial portal 1 Lateral malleolus, 2 Medial malleolus, 3 Talus, 4 Tibialis anterior tendon, 5 Extensor hallucis longus tendon, 6 Extensor digitorum longus and peroneus tertius tendons, 7 Peroneus brevis tendon, 8 Peroneus longus tendon, 9 Achilles tendon, 10 Tibialis posterior tendon, 11 Flexor digitorum longus, 12 Flexor hallucis tendon (musculotendinous), 13 Deep peroneal nerve and anterior tibial artery and veins, 14 Medial dorsal cutaneous nerve (medial terminal branch of superficial peroneal nerve), 15 Intermediate dorsal cutaneous nerve (lateral terminal branch of superficial peroneal nerve), 16 Posterior tibial nerve and posterior tibial artery and veins, 17 Sural nerve and small saphenous vein, 18 Saphenous nerve and great saphenous vein, 19 Posterior peroneal artery and 20 Anterior peroneal artery

Fig. 2

Anatomical dissection of the cutaneous nerves of the foot and ankle. 1 Superficial peroneal nerve, 2 Fascial piercing of the superficial peroneal nerve, 3 Superficial peroneal nerve before piercing the crural fascia, 4 Anterior compartment of the leg, 5 Lateral compartment of the leg, 6 Medial dorsal cutaneous nerve (medial terminal branch of superficial peroneal nerve), 7 Intermediate dorsal cutaneous nerve (lateral terminal branch of superficial peroneal nerve), 8 Lateral dorsal cutaneous nerve (terminal branch of sural nerve), 9 Sural nerve (the saphenous vein was removed), 10 Medial calcaneal nerve (Branco or sural nerve), 11 Common nerves digital of medial dorsal cutaneous nerve (medial terminal branch of superficial peroneal nerve), 12 Cutaneous branch (medial terminal branch) of deep peroneal nerve, 13 Superior extensor retinaculum, 14 Inferior extensor retinaculum, 15 Tip of lateral malleolus, 16 Inferior peroneal retinaculum, 17 Achilles tendon and 18 Tuberosity of the V metatarsal bone

Fig. 3

Using the combined ankle plantar flexion and inversion position, the superficial peroneal nerve (the intermediate dorsal cutaneous nerve or lateral terminal branch of superficial peroneal nerve) could be visualized in 3 out of the 10 examined ankles (30%)

Fig. 4

Photograph showing the used method in the study. The course of the superficial peroneal nerve, or if divided its terminal branches, was determined by creating a window (20 mm wide and 15 mm long), only affecting the skin without manipulating the nerve. Manipulating the ankle in the different ankle positions was standardized by means of the Telos stress device (Telos equipment, Weiterstadt, Germany). The reference point was regarded being the combined plantar flexion and inversion position. In this position, the medial edge of the nerve was marked with a pin (yellow in the photography)