Osteochondral lesions of the lateral trochlear ridge: a rare, subtle but important finding on advanced imaging in patients with elbow pain

Objective To characterize the radiographic, CT, and MRI appearance of clinically and/or surgically proven osteochondral lesions of the lateral trochlear ridge. Materials and methods Ten years of medical charts with elbow radiographic, CT, and MRI studies were retrospectively reviewed. Patients with pathology isolated to the lateral trochlear ridge were included. Studies were reviewed by two radiologists. Identifiable pathology on each type of study was noted and characterized. Results Ten elbow studies were included, all from males aged 15 to 58 years (mean 29 years). Five elbow radiographs were normal, one showed mixed lucency and sclerosis of the lateral trochlear ridge, and four demonstrated small osseous fragments adjacent to the ridge. In all cases, CT demonstrated focal lucency at the cortical surface of the lateral trochlear ridge; 8 contained small osseous fragments, axial plane maximum width ranged from 5 to11 mm, depth from 1 to 2 mm. Focal bone marrow edema in the subchondral lateral trochlear ridge was found in the 6 cases with MR images. Two demonstrated linear high signal underlying the in situ osseous fragment, faintly visible on MRI. In 9 cases, arthroscopy was performed within 3 months of imaging. The remaining patient was treated conservatively with casting. Conclusions Osteochondral lesions of the lateral trochlear ridge are rare but important, as these patients go on to arthroscopy at a high rate. If an abnormality of the lateral trochlear ridge is seen or suspected, we recommend CT as the best imaging study to define these lesions.