Use of Anatomical Landmarks in Ankle Arthroscopy to Determine Accuracy of Syndesmotic Reduction: A Cadaveric Study

Background. The aim of this study was to determine the accuracy of ankle arthroscopy as a means for diagnosing syndesmotic reduction or malreduction and to determine anatomical landmarks for diagnosis. Methods. Six matched-pair cadavers (n = 12) with through-knee amputations were studied. Component parts of the syndesmosis and distal 10 cm of the interosseous membrane (IOM) were sectioned in each. The 12 specimens were divided into 2 groups: 6 specimens in the in-situ group fixed with suture button technique and 6 specimens in the malreduced group rigidly held with a 3.5-mm screw. Specimens were randomized to undergo diagnostic arthroscopy by 3 fellowship-trained foot and ankle orthopaedic surgeons in a blinded fashion. Surgeons were asked to determine if the syndesmosis was reduced or malreduced and provide arthroscopic measurements of their findings. Results. Of 36 arthroscopic evaluations, 34 (94%) were correctly diagnosed. Arthroscopic measurement of 3.5 mm diastasis or greater at the anterior aspect of the distal tibiofibular syndesmosis correlated with a posteriorly malreduced fibula. Arthroscopic evaluation of the Anterior inferior tibiofibular ligament (AITFL), IOM, Posterior inferior tibiofibular ligament (PITFL), lateral fibular gutter, and the tibia/fibula relationship were found to be reliable landmarks in determining syndesmotic reduction. An intraclass correlation coefficient (ICC) for interrater reliability of 1.00 was determined for each of these landmarks between 2 surgeons (P < .001). The ICCs between 2 surgeons' measurements and the computed tomography measurements were found to be 0.896 (P value < .001). Conclusions. Ankle arthroscopy is a reliable method to assess syndesmotic relationship when reduced in situ or posteriorly malreduced 10 mm.