Magnetic Resonance Imaging Signal Abnormalities in Enthesopathy of the Extensor Carpi Radialis Longus Origin

PurposeSome surgeons use magnetic resonance imaging (MRI) findings in patients with enthesopathy of the extensor carpi radialis brevis (ECRB) origin (commonly referred to as lateral epicondylitis) to plan and justify surgical treatment. Overinterpretation of defects of the origin of the ECRB or associated abnormalities of the lateral collateral ligament (LCL) could affect decision-making. We tested the hypothesis that patients with MRI signal abnormalities consistent with enthesopathy of the ECRB are equally likely to have findings consistent with an ECRB defect or LCL abnormality whether they are being evaluated as part of preoperative planning for lateral elbow pain or for an elbow condition that does not feature lateral elbow pain.MethodsFor each of 24 consecutive patients with enthesopathy of the ECRB who had MRI for preoperative evaluation, we selected 2 age- and gender-matched controls from a list of patients who had an elbow MRI to evaluate other elbow problems. The origin of the ECRB and the LCL were specifically evaluated.ResultsPatients diagnosed with enthesopathy of the ECRB were significantly more likely than control patients to have signal changes consistent with enthesopathy of the ECRB origin (24 of 24 vs 9 of 48; p < .001). The proportion of patients with a partial thickness defect of the ECRB origin (14 of 24 vs 4 of 9) was comparable between patients diagnosed with enthesopathy of the ECRB origin and controls. Signal changes in the LCL were comparable in patients diagnosed with enthesopathy of the ECRB origin and control patients (8 of 24 vs 2 of 9; p = .27), and no patient had clinical evidence of instability.ConclusionsUse of MRI in the management of patients with enthesopathy of the ECRB origin merits further study.