DISTAL FIBULAR NOTCH - A FREQUENT MANIFESTATION OF THE RHEUMATOID ANKLE

Objective. To describe the distal fibular notch, an infrequently descr ibed manifestation of rheumatoid arthritis, and to speculate on its et iology through gross dissection, histologic correlation and MR imaging . Design and patients: One hundred and twenty-one conventional ankle r adiographs were obtained and reviewed in 76 patients with clinically d iagnosed rheumatoid arthritis. Additional imaging of three ankles was obtained utilizing CT and MR imaging. In addition to evaluating erosiv e changes, note was made of the presence and location of a well-define d scalloped defect along the medial border of the distal fibula. Ankle specimen dissection and histoanatomic examination was performed in an attempt to determine the exact pathogenesis of this fibular notch. Re sults. The distal fibular notch was identified in 52 of 121 ankles (43 %). Seventy-five percent of notches were syndesmotic and extended down to the horizontal ankle joint level, while 25% of notches were syndes motic with extension below the joint. The majority of ankles (79%) dem onstrated coexistent marginal erosions and/or joint narrowing. Ankle s pecimen dissection revealed a single-celled synovial fold within the d istal tibiofibular syndesmotic recess without underlying articular car tilage extension. Conclusion: The fibular notch within the distal tibi ofibular syndesmosis is a frequent manifestation of rheumatoid arthrit is and appears to result from synovial proliferation rather than from mechanical instability.