Magnetic Resonance Imaging Findings of Extensor Carpi Radialis Brevis Origin and Synovial Fold in Lateral Epicondylitis.

Purpose: Magnetic resonance imaging (MRI) is the most widely used imaging to diagnose lateral epicondylitis (LE). However, the importance of MRI findings in LE remains unclear. This study aimed to classify the signal intensity changes of the extensor carpi radialis brevis origin and the shape and length of the synovial fold using MRI and compare them with clinical symptoms. We hypothesized that MRI findings in LE are not associated with clinical symptoms. Methods: Two hundred and forty-three patients (261 elbows, mean age: 51.2 ± 8.5 years, mean duration of LE: 18.2 ± 11.3 months) who were evaluated using pretreatment MRI were included. The signal change of the extensor carpi radialis brevis origin was classified using coronal T2-weighted (T2) imaging and coronal fat-suppressed proton density T2 imaging, and the shape and length of the synovial folds were evaluated using coronal and sagittal T2 imaging. Furthermore, MRI findings were compared with clinical symptoms at the first visit. Results: The number of elbows with high signal intensity on fat-suppressed proton density T2 was 252 of 261 (96.5%), and those on T2 were 207 of 261 (79.3%). Synovial folds were observed in 231 of 261 (88.5%) of the elbows, and synovial folds having a dull shape were observed in 95 of 261 (36.4%) elbows. The length of the synovial fold was >1/3 of the radial head in 87 of 261 (33.3%) of the elbows. There was no statistically significant correlation between the MRI findings and clinical symptoms. Conclusions: A high rate of high signal intensity changes of the extensor carpi radialis brevis origin was observed, and fat-suppressed proton density T2 could detect finer signal changes than T2. Furthermore, synovial folds were found in many cases of LE. However, there was no association between MRI findings and clinical symptoms at first visit. Type of study/level of evidence: Prognostic IV.