Magnetic resonance imaging-detected associated injuries in lateral epicondylitis

Objectives: The objectives of the study are to report the association between the severity of common extensor tendon (CET) injury and additional elbow abnormalities detected on magnetic resonance imaging (MRI) in patients with lateral epicondylitis. Methods: This is a retrospective cross-sectional study that included 144 patients with MRI-confirmed CET injury. Patients with prior elbow surgery, unavailable MRI, or age below 18 years were excluded. Tendon injuries were graded as mild, moderate, or severe. Ligament injuries (lateral ulnar collateral, radial collateral, and medial collateral), muscle injuries, bone injuries, and joint effusion were recorded as present or absent. Associations between tendon injury severity and concomitant abnormalities were analyzed. Results: Of 144 patients, 54.9% were female and 63.9% had right-sided involvement. Tendon injuries were mild in 55.6%, moderate in 36.1%, and severe in 8.3%. Concomitant findings included lateral ulnar collateral ligament injury (51.4%), radial collateral ligament injury (18.1%), medial collateral ligament injury (10.4%), muscle injury (9.7%), bone injury (10.4%), and joint effusion (28.5%). Tendon severity was significantly associated with lateral ulnar collateral ( p < 0.001), radial collateral ( p = 0.002), medial collateral ( p < 0.001) ligament injuries, and joint effusion ( p = 0.005). Conclusion: MRI demonstrated that lateral epicondylitis commonly coexists with ligament and joint abnormalities, and tendon injury severity correlates with ligament injury and joint effusion. Prospective studies are needed to evaluate long-term functional outcomes.