Radiographic Evaluation of the Normal Distal Tibiofibular Syndesmosis in Neutral to Dorsiflexion on Weight-Bearing

CATEGORY: Ankle; Sports INTRODUCTION/PURPOSE: Reliable landmarks of ankle syndesmosis change in various position is important for managing ankle injury. The purpose of our study was to investigate and compare radiographic landmarks of normal ankle in various positions. METHODS: The study involved both ankle radiographs of 30 subjects (15 males, 15 females) without clinical or radiographic abnormality. Tibiofibular clear space (TFCS) and tibiofibular overlap (TFO) were measured on anteroposterior (AP) and mortise radiographs in non-standing (NS) and standing (S) neutral and dorsiflexion 10 (DF10) and 20 degrees (DF20). The radiographic measurements were used to calculate means, standard deviations, and intra- and interobserver reliabilities, and compare TFCS and TFO in various positions and genders. RESULTS: On the AP view, the mean TFCS in NS, S, DF10, and DF20 positions were 4.00+-0.97, 4.00+-0.83, 4.35+-0.95, and 4.45+-0.89 and the mean TFO on the same positions were 6.58+-2.27, 4.27+-1.90, 3.44+-1.96, and 2.38+-1.91. On the mortise view, the mean TFCS in NS, DF10, and DF20 positions were 3.62+-0.88, 4.08+-0.86, and 3.88+-0.97 and the mean TFO on the same positions were 3.57+-2.13, 2.31+-1.77, and 3.57+-2.14. The reliabilities in all positions except TFCS on some positions were excellent. No measurement was significantly different between females and males except TFO in NS on mortise view (p=0.006) and DF10 on AP view (p=0.032). CONCLUSION: Increase of TFCS and decrease of TFO on AP view reflects syndesmosis change from non-standing to DF20 on standing. Clinically, Effect of weight-bearing and reliability of TFO should be considered.