Comparison of Visibility and Risk of Neurovascular Tissue Injury Between Portals in Needle Arthroscopy of the Anterior Ankle Joint: A Cadaveric Study

BACKGROUND: For needle arthroscopy with 0° viewing, the visible range of intra-articular structures and the difference between portals remain unknown, as do the risks for neurovascular tissue at each portal. PURPOSE: To clarify the visibility and safety of needle arthroscopy. STUDY DESIGN: Descriptive laboratory study. METHODS: Ten cadaveric ankle specimens were used. A needle arthroscope with a 1.9-mm diameter was inserted from 4 portals (anteromedial [AM], anterolateral [AL], medial midline [MM], and anterocentral [AC]). Visibility was assessed using a 15-point ankle arthroscopy checklist. In addition, the ankles were dissected to measure the distance between each portal and neurovascular tissues. The visibility of the ankle joint was compared between portals. RESULTS: The success rate of visibility in the deltoid ligament and the tip of the medial malleolus was 100% from the AM, MM, and AC portals and 10% from the AL portal, with significant differences between the portals (P < .01). The visibility success rates in the origin of the anterior talofibular ligament and the tip of the lateral malleolus were 20% for the AM portal, 90% for the MM and AC portals, and 100% for the AL portal, with significant differences between the portals (P < .01). All other points of the ankle joint were visualized from all the portals with a 100% success rate. The AC portal was in contact with the anterior neurovascular bundle in 4 of the 10 specimens. CONCLUSION: When needle arthroscopy was performed from the AM or AL portal, the site opposite to the portal in the ankle joint was difficult to visualize. Conversely, most points of the ankle joint could be visualized from the MM and AC portals. Care should be taken when creating an AC portal because of its proximity to the anterior neurovascular bundle. CLINICAL RELEVANCE: The present study provides information regarding which portal should be selected to perform needle arthroscopy in the ankle joint, which will be beneficial for management of ankle injuries.