This 63-years old man has marked cartilage loss as seen on the sagittal image (arrows) with mild marrow edema. He has difficulty in walking, gradually progressive for the last 10 years, with acute exacerbation in the last 1 month with a history of a mild twisting injury.

On the MRI, the marrow edema is part of the acute exacerbation, but the root tear seen involving the posterior horn of the medial meniscus on the coronal image is the result of the twisting injury. This usually leads to further acceleration of degeneration because of changes in the stress response by the meniscus and signals the need to eventually go in for a total knee replacement (TKR).

The sagittal image shows cartilage loss with marrow edema and a Baker’s cyst. The coronal image shows a tear of the root of the posterior horn of the medial meniscus