The anteromedial portal is the first to be performed. It is established just medial to the tibialis anterior tendon at the anterior joint line of the ankle and coinciding with a soft spot, a visible and palpable depression seen when the ankle is in dorsiflexion (Figs. 3.10 and 3.11). It is important to palpate the tibialis anterior tendon with the ankle in the dorsiflexed position. There is a potential for injury to the saphenous nerve and the great saphenous vein, which at this level, divides into numerous branches that communicate with the deep venous system (Fig. 3.12). These structures lie at a mean safe distance of 9 mm (3–16 mm) from the saphenous vein and 7.4 mm (0–17 mm) from the saphenous nerve (Feiwell and Frey 1993). Although some investigators consider these structures risk-free (Saito and Kikuchi 1998), Chen reported one case of saphenous vein lesion in 67 ankles treated with arthroscopy (Chen 1976); Ferkel and Fischer described 27 neurologic complications, 5 corresponding to saphenous nerve injuries (Ferkel and Fischer 1989); and Zengerink and van Dijk reported two cases in a large series of 1,305 arthroscopies (Zengerink and van Dijk 2012).

At the anterior edge of the tibia, where it joins with the medial malleolus, there is a notch (medial notch of Harty) (Harty 1985) that provides the anteromedial portal with additional space to allow easier passage of the instruments in the anteroposterior direction (Guhl 1993) (Fig. 3.13).

The anterolateral portal is created at the anterior joint line just lateral to the peroneus tertius tendon (present in 90 % of cases) (Reinmann 1981) or, in its absence, lateral to the extensor digitorum longus tendons (Figs. 3.10 and 3.14). The main structure at risk of injury when performing this portal is the intermediate dorsal cutaneous nerve (the lateral branch of the superficial peroneal nerve) (Takao et al. 2001). Most of the complications described in arthroscopy of the ankle involve this nerve (Barber et al. 1990; Ferkel et al. 1996; Martin et al. 1989; Zengerink and van Dijk 2012) (Fig. 3.15).

The superficial peroneal nerve, which is the motor for the muscles of the lateral compartment of the leg (peroneus longus and peroneus brevis) and the sensory nerve for the greater part of the dorsal foot, has been the subject of numerous anatomical studies (Adkison et al. 1991; Blair and Botte 1994; Feiwell and Frey 1993; Ögüt et al. 2004; Saito and Kikuchi 1998; Sayli et al. 1998; Takao et al. 1998). After providing motor innervation, the superficial peroneal nerve runs along the lateral intermuscular septum. The superficial peroneal nerve usually divides into two branches: the more laterally located, the intermediate dorsal cutaneous nerve and the medial dorsal cutaneous nerve (Fig. 3.14). Various types or patterns have been described according to the level and manner in which the superficial peroneal nerve divides into its branches (Adkison et al. 1991; Blair and Botte 1994; Saito and Kikuchi 1998; Sayli et al. 1998; Takao et al. 1998).

The arthroscopist should be aware that this important nerve lies very close to the anterolateral portal and that a protocolled arthroscopic technique can avoid injury to this structure.

It is fortunate that this nerve is visible on clinical examination (it is the only nerve in the body that can be seen in this way) (Stephens and Kelly 2000). By performing inversion of the ankle, the nerve is tensed (particularly the intermediate dorsal cutaneous branch), and its subcutaneous course becomes evident (Ferkel 1996). De Leeuw et al. reported that the superficial peroneal nerve moves in a lateral direction in relation to the skin when the ankle is moved back from this inverted position to the neutral position. This movement is mean 3.6 mm to the lateral side. It is therefore important to stay on the medial side of the cutaneous nerve marking, performed in inversion of the ankle (de Leeuw et al. 2010).

A vertical incision affecting only the skin, together with blunt dissection up to the capsule, contributes to decreasing the risk of injury to the nerve. The anterolateral portal can also be created by an inside-out technique through the anteromedial portal, similar to the way the anterior portal is made in arthroscopy of the shoulder. Cutaneous transillumination obtained in this manner allows localization of the superficial peroneal nerve (intermediate dorsal cutaneous nerve) (Ferkel et al. 1996; Barber et al. 1988).

The medial midline portal, with the aim of obtaining an interarticular view similar to the anterocentral portal, but with a lower risk of lesion to vital structures, was first described by Buckingham et al. (1997).

The anterocentral portal is established between the extensor digitorum longus tendons at the level of the joint line. This portal provides a wide field of view and facilitates passage of the instruments in the anteroposterior direction (Guhl 1988). Nevertheless, most investigators discourage the use of this portal because there is a high associated risk of injury to numerous neurovascular structures, and today is an unused portal.

The medial midline portal is located just lateral to the tibialis anterior tendon, between the tibialis anterior and the extensor hallucis longus tendon, which is located medial to the portal.

This approach can also be used to introduce fluid into the joint.

Additional portals can be performed distal to the anterolateral and anteromedial portals. The separation between the main portal and the accessory portal should be wide enough to allow proper triangulation and instrumentation and to avoid the risk of cutaneous necrosis (around 5 mm).

These portals can facilitate the instrumentation in certain cases or can be used to introduce fluid into the joint.

The standard posterolateral in combination with anterior portals is the most widely used of the posterior portals because it presents the lowest risk of neurovascular injury. It is located 1.2–2.5 cm proximal to the tip of the lateral malleolus, adjacent to the lateral axis of the calcaneal or Achilles tendon (Ferkel 1996). The sural nerve and its branches and the small saphenous vein are in close proximity and at risk of injury (Ferkel et al. 1996; Guhl 1988; Martin et al. 1989). Ferkel et al. reported five cases of sural nerve lesion in 612 arthroscopic procedures of the ankle (Ferkel et al. 1996). According to Feiwell and Frey, the sural nerve is located at a mean distance of 6 mm (0–12 mm) and the small saphenous vein at 9.5 mm (2–18 mm) from the posterolateral portal (Feiwell and Frey 1993).

This portal is usually made with an outside-in technique. It is also possible to use an inside-out technique for this purpose (Katchis and Smith 1997), but considerable articular distraction is required to overcome the difference in positioning of the two joint lines, necessary for anteroposterior passage of the instruments.

In any case, after meticulous anatomical study of the posterior ligaments of the ankle joint (Golanó et al. 2002) and having performed and observed numerous arthroscopic procedures in this articulation, the authors concluded that the posterolateral portal is always established between two posterior ligaments of the ankle joint—the transverse ligament and the posterior intermalleolar ligament—which are constant and visible by arthroscopy. In dorsiflexion, the arrangement of these ligaments, together with the tibia, delimits a triangular area, with the base at the tibia and the tip at the lateral malleolus (Golanó et al. 2002). This space is similar to the anatomical intra-articular triangle of the shoulder used as a landmark to safely establish the anterior portal, as described by Matthews et al. (1985).

Even though numerous portals for accessing the ankle joint have been described and there are several available systems of distraction, the morphology of the joint makes access to the posterior region from the anterior portals difficult.

For this reason and with the aim of resolving treatment of periarticular pathology, van Dijk et al. described two posterior endoscopic portals that allow better access to the posterior aspect of the ankle and the subtalar joints (van Dijk et al. 2000).

To use these portals, the patient must be in the prone position. By means of this technique, it is possible to inspect and treat lesions in the posterior part of the ankle joint and pathology in the subtalar joint.

The posterolateral portal is created at the same level as or slightly above the tip of the lateral malleolus, just lateral to the calcaneal tendon. A blunt dissection is performed with a vascular or mosquito clamp, and the arthroscope shaft with a blunt trocar is inserted in the direction of the web space between the first and second toe until it touches the talar bone.

Subsequently, the posteromedial portal is established at the medial edge of the calcaneal tendon, at the same height as the posterolateral portal. The direction of the portal is the most important aspect to consider. The mosquito clamp is introduced and then arthroscope shaft with the blunt trocar is inserted in a medial-to-lateral direction until it touches the arthroscope shaft positioned in the posterolateral portal. It then slides along the shaft, which acts as a guide, until the tip is reached (Fig. 3.16). After the periarticular fatty tissue is removed. During resection of the periarticular fatty tissue, fascial fibers that have a transverse course and a consistent appearance can easily be recognized (Golanó et al. 2006a, b). These fibers are part of the deep crural fascia that, because of its constant movement, is considerably thickened at the level of the ankle joint. In 1932, Rouvière and Canela-Lázaro gave this structure the name fibulotalocalcaneal ligament (Rouvière and Canela-Lazaro 1932) (Figs. 3.17 and 3.18). The flexor hallucis longus tendon, the lateral talar process, the ankle joint capsule with the posterior ligaments of the joint, and the subtalar joint capsule can be identified. Among these structures, the flexor hallucis longus tendon acquires special relevance because the tibial neurovascular bundle (tibial nerve, posterior tibial artery and veins) is located medial to it (Fig. 3.17). Care should be taken to avoid injury to the flexor hallucis longus tendon, which is considered the main endoscopic landmark because its lateral border determines the working area. Proper positioning of the ankle and the hallux results in better visualization of the tendinous portion of the flexor hallucis longus muscle and avoids unnecessary resection of some of the muscle fibers that reach the lateral tendinous border in a semipeniform morphology. Plantar flexion of the ankle or hallux flexion facilitates visualization of the flexor hallucis longus tendon proximal to the lateral talar process.