Medial subtalar arthroscopy: a cadaveric study of the tarsal canal portal

Abstract

PURPOSE: To study the safety of the tarsal canal portal in medial subtalar arthroscopy. METHODS: Twenty-three fresh frozen foot and ankle specimens were divided into two groups with different orientation of the portal tract. Three types of tarsal canal portals were identified. The relationships of the metal rod and the flexor digitorum longus tendon and the posterior neurovascular bundle were studied. RESULT: In group A, a type 1 tarsal canal portal tract was established in seven specimens, a type 2 portal tract in three specimens, and a type 3 portal tract in two specimens. In group B, a type 1 portal tract was established in ten specimens and a type 2 portal tract in one specimen. No type 3 portal tract was established in group B. There was no statistical significance demonstrated for establishment of a type 1 portal tract and 'non type 1' (type 2 or 3) portal tract in group A and group B. The average shortest distance between the rod and the posterior tibial neurovascular bundle was 7 mm in group A and 9 mm in group B. CONCLUSIONS: This study provides the anatomic basis for the establishment of the tarsal canal portal. There is a risk of injury to the flexor digitorum longus tendon and the posterior tibial neurovascular bundle with the tarsal canal portal, and it should be used with great caution.