June 9, 2023

There has been a lot of discussion about OA structural phenotypes and how we can distinguish them from OA disease severity. Likely, it really depends on the predominant tissue involved. This example is a knee with advanced medial OA and marked tibial and femoral bone marrow lesions (arrows). In addition, there is marked meniscal extrusion (arrowhead) and diffuse full thickness cartilage loss in the medial compartment. Based on the large bone marrow lesions, this knee would be considered a predominant subchondral bone phenotype. Phenotypic overlap is a challenge that needs to be resolved. This knee also exhibits marked joint effusion (asterisk) and would fulfill the criteria of an inflammatory phenotype as well