OBJECTIVETo conduct the anatomical study about the posterior coaxial portals via posterior tibial tendon (PTT) sheath for ankle arthroscopy.

METHODSCoaxial portals were established in 20 ankles by K-wires which were left in place for distance measurement between them and the posterior nerves, tendons and vessels. Ankle arthroscopy was performed in 5 fresh ankles using 2.7 mm 300 arthroscopy with the same portals as mentioned above. The maximum visible scope were recorded and the distance between the arthroscopy and the posterior nerves, tendons and vessels was also measured.

RESULTSThe medial portal was located 5 - 12 mm (average, 8 mm) above the tip of medial malleolus, and the lateral portal was located 8 - 24 mm (average, 15 mm) above the tip of lateral malleolus. The coaxial portals, which traversed the PTT sheath and passed posterior to the fibular, not only separated the arthroscopy and instrument from the posterior nerves, tendons and vessels by posterior capsule but also enlarged their distance. The medial and lateral malleolus articular gap, the posterior capsule could be viewed by these portals with as much as 1/2 - 2/3 posterior articular surface of talus. Not only the tibiotalar articular gap but also the dynamic movement between the mortise and the talus were clearly observed. Arthroscopic operation could be performed by instrument through the posterolateral portal.

CONCLUSIONSThe posterior coaxial portals via PTT sheath for ankle arthroscopy have such advantages as easy maneuverability, superior safety, clear vision and larger operation field under arthroscopy.