Second and Third Metatarsophalangeal Plantar Plate Tears: Diagnostic Performance of Direct and Indirect MRI Features Using Surgical Findings as the Reference Standard

OBJECTIVE. The objective of our study was to assess the diagnostic performance and associations of the direct and indirect MRI features of the metatarsophalangeal (MTP) joint that are thought to be related to tears of the plantar plate (PP) using surgical findings as the reference standard. MATERIALS AND METHODS. We retrospectively included 23 patients with symptomatic instability of lesser MTP joints who had undergone preoperative 1.5-T MRI and surgical assessment. The MRI examinations were independently assessed by two musculoskeletal radiologists. Using the surgical data as the reference standard, we calculated the sensitivity, specificity, and accuracy of each MRI feature in the detection of PP tears. Multivariate logistic regression analysis was performed to identify which MRI features were independently associated with PP tears. Interobserver reliability was assessed using kappa statistics. RESULTS. Forty-five lesser MTP joints were included. The presence of pericapsular fibrosis was highly sensitive (91.2%), specific (90.9%), and accurate (91.1%) for the diagnosis of PP tears. With a cutoff value of 0.275 cm, the PP-proximal phalanx distance had a sensitivity of 64.7%, specificity of 90.9%, and accuracy of 71.1% in diagnosing PP tears. CONCLUSION. In patients with clinical features indicating lesser MTP joint instability, some direct and indirect MRI features exhibited good to excellent diagnostic performance in detecting the presence of PP tears.