Ultrasound diagnosis of chondrocalcinosis in the knee.

The radiographic diagnosis of calcium pyrophosphate dihydrate (CPPD) deposition disease is usually made by observing calcifications in the articular cartilage of large joints or, in the knee, noting calcification in the menisci. Sonography is useful in evaluating the patellofemoral joint, including the trochlear cartilage, which is often difficult to image adequately on conventional radiographs, as true tangential views of the patellofemoral joint may be difficult to obtain. We describe a case of sonographic detection of cartilage calcification in the trochlea of the knee which was radiographically occult.