Patient History
7-year-old girl who presents with right knee pain
Findings
Large joint effusion with reactive synovitis without internal debris or free bodies.
Lateral retinaculum and medial patellofemoral ligament are intact.
Patellar Cartilage: No chondromalacia or osteochondral defects.
Trochlear Cartilage: No chondromalacia or osteochondral defects.
Quadriceps Tendon/Patellar Tendon/Flexor Mechanism: Normal.
ACL: Intact.
PCL: Intact.
MCL: Intact.
Lateral Collateral Complex: Intact.
Posterolateral Corner: Intact.
Posteromedial Corner: Intact.
Medial Meniscus: Intact.
Lateral Meniscus: Intact.
Medial Compartment Cartilage: No chondromalacia or osteochondral defects. No osteoarthrosis.
Lateral Compartment Cartilage: Focal punched out cortical erosion posteromedial aspect of lateral tibial plateau weightbearing surface associated with a subchondral cyst.
Musculature: No fatty infiltration or volumetric atrophy.
Marrow Signal: Normal.
No soft tissue masses or cysts. Normal neurovascular bundle.
Impressions
1. Right knee large joint effusion with reactive synovitis and no internal debris. Punched out cortical erosion localized to the posteromedial lateral tibial plateau. Given the patient's demographics, this raise suspicion for Juvenile Rheumatoid Arthritis (JRA).
2. Focal penetrating chondral fissure with a subchondral arthropathic cyst at the posteromedial aspect of the lateral tibial plateau.
