Pain in left knee. Is there a Baker's cyst or other pathology in the posterior knee? Also, what is the sclerotic focus mentioned in the April 22 knee radiograph? Exquisite tenderness and posterior knee with palpation. Evaluation the knee is limited on some sequences by motion artifactMENISCI: There is marked attenuation of the body and much of the posterior horn of the lateral meniscus, presumably reflecting extensive attritional tearing assuming there has not been a prior partial meniscectomy. The tearing also extends anteriorly to involve the inner fibers of the anterior horn of the lateral meniscus. There is also diffuse attenuation of the medial meniscus likely representing chronic attritional tearing in the absence of prior partial meniscectomy. Additionally, however, there is a complete longitudinal (vertical) tear of the posterior horn of the medial meniscus near the red-white junction.ARTICULAR CARTILAGE AND BONE: Severe osteoarthritis affects the knee with much of the lateral tibiofemoral compartment devoid of articular cartilage, particularly posteriorly. Abnormal subchondral signal intensity in the lateral femoral condyle and tibial plateau is likely degenerative in etiology. There is also subjective thinning of the articular cartilage of the medial tibiofemoral compartment and moderate degeneration of the articular cartilage of the patellofemoral compartment with focal areas of full-thickness cartilage loss. There are tricompartmental osteophytes. There is an irregularly-marginated cortically-based focus of low signal intensity within the distal femoral metaphysis medially that corresponds to the sclerotic focus seen on recent radiographs. Small foci of high signal intensity are noted adjacent to this abnormality on the fluid sensitive sequences. I suspect that this represents the residua of an involuted benign fibroxanthoma (nonossifying fibroma).LIGAMENTS: The cruciate and collateral ligaments are intact. EXTENSOR MECHANISM: The extensor mechanism is intact.ADDITIONAL
1.Severe osteoarthritis, particularly affecting the lateral tibiofemoral compartment.2.Attenuation of the menisci likely represents extensive chronic attritional tearing (assuming there has not been prior partial meniscectomy); there is also a complete longitudinal tear of the posterior horn of the medial meniscus.3.Although I see no Baker cyst, there is a joint effusion with a small amount of fluid extending posteriorly through a small rent in the posterior capsule.4.Predominantly low signal intensity focus within the distal femoral metadiaphysis corresponds to the sclerotic focus seen on radiographs. I suspect that it represents the residua of a involuted fibroxanthoma (nonossifying fibroma).