Hi my name is Lauren Rudolph from Boulder Biologics and Rocky Vista University and this is an ultrasound consult for a knee joint effusion with CPPD. Ultrasound in this case revealed a large effusion on the right knee with no effusion in the contralateral knee. So let's start with a normal companion case. On the left is a normal view of the anterior knee. We're using a high frequency linear array transducer. We are looking long access to the quadriceps tendon and you can see this faint hypoechoic line here which is the suprapatellar recess located between the pre femoral fat pad superficially and the quadriceps fat pad deep. On the right of the screen is a patient with a moderate effusion with calcium pyrophosphate crystals in the effusion that appear hyperechoic. So let's take a closer look at this abnormal companion case. Here again we are at the anterior knee and long access to the quad tendon and we're showing compressibility of the suprapatellar recess. Noticing the sort of sparkling hyperechoic deposits within the synovial fluid. This patient had some additional characteristic ultrasound CPPD disease findings. Here is a medial longitudinal view of the knee with the medial collateral ligament in long access and you can see aggregates of meniscal calcifications. Again same patient now scanning the posterior knee and looking at the medial and lateral femoral condyles. Notice the left static images you can see hyperechoic deposits within the hypoechoic hyaline cartilage layer. Then on the right in this sine loop we are scanning medial to lateral and lateral to medial. This helps to appreciate the difference between normal hypoechoic cartilage and these inter cartilaginous hyperechogenicities. Also keep in mind this is different than the double contour sign characteristic of gout. With the double contour sign in gout you will see hyperechogenicity on the top of the hypoechoic cartilage whereas here with CPPD you see the hyperechogenicity within the hypoechoic cartilage. And finally a reminder ultrasound can aid in the diagnosis of CPPD disease with characteristic findings as we've seen in previous slides however it is not the diagnostic gold standard. Here is the 2023 classification criteria for CPPD disease from the American College of Rheumatology and while the diagnosis of CPPD disease is beyond the scope of this talk basically arthrocentesis with subsequent crystal analysis remains the gold standard for diagnosis. However ultrasound imaging is included in the scoring criteria and here is a reference for the previous article.

3rd Edition, CASE 48

3rd Edition

Rheumatology

CPPD

knee effusion

ultrasound

hyperechoic crystals

arthrocentesis