Flouroscopic arthrography versus MR arthrography of the lesser metatarsophalangeal joints for the detection of tears of the plantar plate and joint capsule: a prospective comparative study.

Background: Derangements of the plantar plate and joint capsule are an underrecognized cause of lesser metatarsalgia. Fluoroscopic arthrography and magnetic resonance (MR) arthrography are both used for diagnosis. Currently there are no studies comparing the effectiveness of these two modalities.

Methods: Patients suspected of having plantar plate or capsular tears underwent both fluoroscopic arthrography and MR arthrography; the imaging findings were then compared and correlated with intraoperative findings, when available, to evaluate the effectiveness of the different imaging modalities. Forty consecutive patients underwent both fluoroscopic and MR arthrography.

Results: Thirty-two of 40 patients (80%) were found to have tears of the plantar plate, joint capsule, or both. MR arthrography identified all 32 tears. Four cases in the first 29 patients, 13.8%, demonstrated discrepancy where a tear was identified only on the MR arthrogram. A midpoint review of the data was performed. Of the 4 missed tears they were all noted to be plantar lateral in location. Four other patients in this group had plantar lateral tears that were not missed. These patients had an additional steep lateral oblique image on fluoroscopic arthrography, which showed the plantar lateral tear. Therefore an additional steep lateral oblique image was performed routinely capturing these small tears in the last 11 patients.

Conclusion: MR arthrography was more accurate in identifying tears of the plantar plate and capsule than fluoroscopic arthrography. Fluoroscopic arthrography with additional views, like a steep lateral oblique view, was found to be as reliable, and more cost-effective, than MR arthrography.

Level Of Evidence: Level II, prospective comparative study.