CLINICAL HISTORY: 47 year old female with history of rheumatoid arthritis
with swelling and pain for 1 year. Concern for cyst.
MRI TECHNIQUE: GE 1.5 Tesla, sagittal SE T2 images, sagittal gradient echo
T2 images and coronal T1 SE images were obtained.
FINDINGS: Advanced arthritic changes of the knee. There is narrowing of
both the medial and lateral femoral tibial joint space, great medially. There is extensive medialsubchondral
slerosis and cyst formation of both the femoral condyle and the tibialplateau. Probable marginal erosions
are present here, as well. There are erosions of the posterior femoral condyle just beneath the heads of
the gastroc muscles. There is also derangement of the knee without an absent anterior cruciate ligament,
presumably from old injury and macerated and almost absent medial and lateral mensici. The patellar cartilage
is preserved. An enormous popliteal cyst extends from the popliteal region down along the medial calf for
a length of approximately 15 cm. A moderate joint effusion is present as well. The findings may all be
the result of a longstanding rheumatoid arthritis. Some, however, post traumatic changes may also be involved.
The unusual large popliteal cyst may be related to rheumatoid arthritis. No definite pannus can be seen
within the synovial spaces.
