The magnetic resonance imaging appearance of the normal anatomy and injury pattern of capsuloligamentous complex of the first metatarsophalangeal joint

Background The capsuloligamentous complex injury of the first metatarsophalangeal joint (MTPJ) is a common cause of turf toe.Purpose To investigate whether high-resolution 3 T magnetic resonance imaging (MRI) could demonstrate all the normal anatomic structures and the MR features of the capsuloligamentous complex injury of the first MTPJ, and to evaluate the diagnostic performance of MRI in the diagnosis of the capsuloligamentous complex injuries of the first MTPJ.Material and Methods A total of 115 feet were included in this study, including 48 feet from 24 healthy volunteers and 67 feet from 67 patients with the capsuloligamentous complex of the first MTPJ injuries. All feet had MRI examination. The MRI features of the capsuloligamentous complex of the first MTPJ of the volunteers and patients were analyzed. Diagnostic sensitivity, specificity, and accuracy of MRI were calculated using the surgery as the standard of reference. The inter-observer agreement was assessed using kappa analysis.Results The central portion of the plantar plate and ligament injury manifested as discontinuity, with an indistinct appearance with hyperintense signal within the involved structures. The sensitivities, specificities, and diagnostic accuracy value of MRI for diagnosing most structures of the capsuloligamentous complex injuries of the first MTPJ were 67%-100%, 93%-100%, and 0.82-0.99, respectively, and overall good to perfect inter-observer agreements (kappa=0.63-0.95).Conclusion High-resolution MRI allows adequate visualization of normal anatomic structures of the first MTPJ. The best visualized structure is sesamoid phalangeal ligament and the most frequent injury is complete tear of the medial sesamoid phalangeal ligament.