Bone marrow edema of the knee occurs secondary to a myriad of causes. The hallmark of a bone marrow lesion (BML) is an area of decreased signal intensity on T1 weighted MRI with a corresponding area of increased signal intensity on a T2 weighted MRI. Recently, chronic bone marrow lesions have been correlated with knee pain and progression of osteoarthritis. These lesions have also been associated with other degenerative conditions such as meniscal tears, cartilage deterioration, subchondral cyst formation, mechanical malalignment, and ultimately progression to arthroplasty. Medical treatments, such as prostacyclin and bisphosphonate therapy, have shown promise. Alignment procedures, as well as core decompression and subchondroplasty, have been used as surgical treatments for chronic BMLs.