Assessment of the Location of the Peroneus Longus Tendon in the Cuboid Groove Using 3D Isotropic Fast Spin-Echo MRI

Purpose: To investigate normal location of the peroneus longus tendon (PL) in the cuboid groove by evaluating it between ankles with no significant abnormality (asymptomatic group) and those with retromalleolar PL dislocation (dislocation group) using three-dimensional isotropic fast spin-echo (3D-FSE) magnetic resonance imaging (MRI) of the ankle. Materials and Methods: Thirty-six and 32 3D-FSE ankle MRI were assigned to the asymptomatic group and the dislocation group, respectively. Using multiplanar reformatted 3D-FSE, qualitative PL location (i.e., outside, overlying, and inside in relation to the cuboid groove), quantitative PL location (i.e., distance between the proximal margins of PL and cuboid groove), and cuboid groove size were measured in lateral, middle, and medial levels of the cuboid groove. Results: In the asymptomatic group, 64%, 42%, and 11%, respectively, had the outside or overlying-located PL in lateral, middle, and medial levels of the cuboid groove and the quantitative location gradually decreased from lateral to medial level. Qualitative and quantitative PL locations were not significantly different between the asymptomatic group and dislocation group. Cuboid groove size showed significant negative correlation with quantitative PL location in both groups. Conclusion: Outside-or overlying-located PL in lateral and middle levels of the cuboid groove would be a normal finding, regardless of PL status at the retromalleolar level.