Posteromedial rotatory instability of the elbow: What the radiologist needs to know

•Elbow posteromedial rotatory instability consists of an anteromedial coronoid fracture with proximal avulsion of the lateral collateral ligaments and ulnar collateral ligament posterior bundle tear.•It can lead to persistent elbow instability, progressive cartilage damage and early osteoarthritis. Surgical treatment is indicated in patients with ongoing instability.•CT and MRI can provide valuable information about the coronoid fracture morphology and the degree of ligamentous injuries respectively, and help guide the management decisions.