23 year old male. Reactive arthritis. History of large effusion. MENISCI: The medial and lateral menisci are intact without evidence of a tear.ARTICULAR CARTILAGE AND BONE: Mild edema type signal in the posterior medial tibial plateau suggestive of a small contusion. No bone erosion is evident. Patellofemoral and tibiofemoral compartment cartilage is intact without a focal defect.LIGAMENTS: ACL, PCL, MCL, and LCL are intact. EXTENSOR MECHANISM: The quadriceps and patellar tendons are intact with normal signal and morphology.ADDITIONAL
Large knee joint effusion. Edema type signal at the posterior medial tibial plateau suggestive of a small contusion. No evidence of a meniscal or ligamentous injury.