Posterior Translation of the Radial Head in Magnetic Resonance Imaging of Lateral Epicondylitis.

Background: Posterolateral rotatory instability is produced by disruption of the lateral collateral ligament complex (LCLC); it is commonly induced by trauma, with few cases reported due to lateral epicondylitis. We examined the amount of posterior transition of the radial head with or without LCLC injury, common extensor tendon (CET) injury, and Baker classification in lateral epicondylitis. Methods: We retrospectively studied patients with lateral epicondylitis of the humerus who underwent surgery between April 2016 and July 2021. Fifteen elbows with coronal and sagittal images on preoperative magnetic resonance imaging (MRI) were included. We investigated the amount of posterior transition of the radial head in sagittal MRI images of the elbow, which were compared based on LCLC and CET lesion. Results: The mean age of patients was 49 years. The lesions in four, nine, and two patients were classified as LCLC0, LCLC1, and LCLC2, respectively. The mean radio-humeral distance values among the LCLC lesions were 0.65, 2.46, and 2.22 mm in LCLC0, LCLC1, and LCLC2, respectively, with the RHD between LCLC0 and LCLC1 differing significantly. In five, six, and four patients, the lesions were classified as CET1, CET2, and CET3, respectively. The mean RHD values among the CET lesions were 1.33, 2.68, and 1.48 mm in CET1, CET2, and CET3, respectively. Conclusions: Our results showed that posterior transition of the radial head is greater in patients with lateral epicondylitis with LCLC lesions on MRI than those with normal findings of LCLC.