Ankle Arthroscopy Portals - Anterior and Posterior

ANTERIOR PORTALS

1. Anteromedial Portal (established first)

• Location: Just lateral to the medial malleolus, immediately medial to the tibialis anterior tendon, at the joint line
• Technique: Dorsiflex the ankle to open the joint space; insufflate with saline via 18G spinal needle first; use "nick-and-spread" blunt dissection
• Structures at risk: Saphenous nerve and great saphenous vein
• Established first because fewer structures are at risk than the anterolateral

2. Anterolateral Portal

• Location: Anterior to the fibula, lateral to the extensor digitorum longus tendon, at the joint line
• Technique: Mark the superficial peroneal nerve before making this portal - visualize it by plantarflexing and inverting the foot; it moves laterally when foot goes to neutral/dorsiflexion
• Structures at risk: Intermediate dorsal cutaneous branch of the superficial peroneal nerve (most commonly injured nerve in ankle arthroscopy; 68% of cadavers had a branch near this portal); peroneus tertius tendon
• The nerve crosses near this portal in 83% of specimens

3. Anterocentral Portal (accessory/seldom used)

• Location: Between the two main anterior portals, along the extensor hallucis longus tendon
• Structures at risk: Anterior tibial neurovascular bundle (deep peroneal nerve + dorsalis pedis artery) - generally avoided for this reason

POSTERIOR PORTALS

1. Posterolateral Portal (established first / arthroscope portal)

• Location: 1 mm anterior to the lateral border of the Achilles tendon, at the intermalleolar line (level of the ankle joint)
• Technique: A blunt trocar is inserted directed toward the lateral border of the 3rd metatarsal (aim toward 1st web space) to avoid the neurovascular bundle; stay lateral to the FHL tendon; use "nick-and-spread" for skin
• Structures at risk: Branches of the sural nerve and small saphenous vein - placing the portal too laterally risks the sural nerve
• The arthroscope is inserted through this portal

2. Posteromedial Portal (working/instrument portal)

• Location: 1 mm anterior to the medial border of the Achilles tendon, at the same level as the posterolateral portal
• Technique: Establish after the arthroscope is in the posterolateral portal; instruments (shaver, probes) inserted here
• Structures at risk: Posterior tibial neurovascular bundle (tibial nerve + posterior tibial artery and vein); these must be avoided by staying medial to the FHL tendon
• Key rule: keep all instruments lateral to the FHL tendon - FHL is the "lighthouse" protecting the neurovascular bundle

3. Trans-Achilles Portal (accessory, rarely used)

• Location: Directly through the Achilles tendon
• Occasionally used for specific posterior procedures

Summary Table

Key Operative Pearls

• SPN identification: Plantarflex + invert the 4th toe to visualize the superficial peroneal nerve before making the anterolateral portal; 49% of ankle arthroscopy complications involve nerve injury
• Nick-and-spread technique is essential at all portals to avoid nerve laceration
• FHL as a landmark: In posterior arthroscopy, the flexor hallucis longus (FHL) tendon is the key safe-zone boundary - instruments must stay lateral to it to protect the posterior tibial NV bundle
• Anteromedial before anterolateral (fewer at-risk structures anteriorly)
• Posterolateral before posteromedial (arthroscope in PL, instruments in PM)
• Posterior third of talar dome is inaccessible from anterior approach in ~55% of cases - use posterior portals for posterior talar pathology