61 year old male presents with left knee pain and swelling. There is clinical concern for a septic knee. There is a fluid collection in the soft tissues of the knee anterior to the patella and the patellar tendon. This collection measures 2 x 1 cm in transverse dimension. The collection has irregular margins which enhance and there is enhancing reticulation of the surrounding soft tissues indicating inflammation. This is compatible with an abscess though could represent bursitis with extensive surrounding inflammation.Bone marrow signal is normal.The extensor mechanism is intact.There is a full thickness defect of the articular cartilage of the medial femoral condyle just above the posterior horn of the medial meniscus measuring approximately 1cm in diameter. There are additional full thickness clefts in the articular cartilage of the femoral trochlea.The cruciate and collateral ligaments are intact.There is a small amount of fluid in the joint but no effusion. There are no other findings that suggest septic arthritis.
Fluid collection in the prepatellar soft tissues with surrounding inflammation suggestive of an abscess or bursitis. Other findings as described above.