[Arthroscopy of the ankle: a new of postero-internal point of entry]

The development of the indications in the arthroscopic surgery of the ankle and the narrowness of this joint impose perfectly adapted portals. Several posterior portals which allow to access to the postero medial corner of the joint have been already described, but are not satisfying. We describe, here, a new postero-medial portal which allows a safe and easy access to the posterior part of the joint.

The arthroscopy is performed with a standard arthroscope (30 degrees, 4.5 mm in diameter) and a lateral ankle distractor. The landmark for this portal is the posterior crest of the medial malleolus. Above the posterior tip of the medial malleolus, this crest is directed up and back, then its direction becomes strictly vertical. The new portal is situated there, 5 millimeters behind the crest (generally 2 centimeters above the posterior tip of the medial malleolus). A needle visualized by the anterior portal is helpful to show the right direction for the portal. After skin incision, a forceps is used to widen the portal. Then the instruments or the arthroscope can be introduced. Posterior tibial artery and nerve are protected by the tendons of tibialis posterior and flexor digitorum longus.

We have used this portal (instrumentation and arthroscope) in four patients (3 osteochondritis dissecans of the medial part of the talus, 1 loose body) without problem.

This portal is safe; it does not intersect the direction of posterior tibial artery and nerve as in the postero-medial portal described by Parisien and avoids in most cases the approach described by Guhl.

Because the medial malleolus is more anterior than the lateral malleolus, it allows a larger approach to the posterior part of the joint than the postero-lateral portal. We recommend it for the arthroscopic treatment of all the lesions of the postero-medial part of the joint.