NWHSU logo
Diagnosis and Discussion—Unknown 3

Diagnosis and Discussion


Calcium pyrophosphate dihydrate deposition disease (CPPD)


Though there are degenerative changes in the knee, the finding of chondrocalcinosis, or calcification of the cartilage sets this apart from simple DJD. Though gout can produce chondrocalcinosis it is extremely rare in the knee. Also, the lack of hyperuricemia speaks against gout. Gout will typically produce marginal, periarticular, or intraosseous erosions.

Calcium pyrophosphate dihydrate deposition disease is a crystal induced arthropathy similar to gout. Calcium pyrophosphate crystals deposit in cartilage and produce chondrocyte death, then cartilage thinning. Minor trauma may cause the crystals to "shed" or break out of cartilage into the joint producing an acute synovitis. The mechanism of how the crystals deposit in cartilage is not known. There is some thought that local tissue damage, either age-related or secondary to trauma, leads to susceptibility for crystal deposition.

CPPD affects both men and women, middle-aged and elderly. The most common presentation resembles degenerative joint disease with the onset occurring after 30 years of age. The symptoms can mimic gout, rheumatoid arthritis, and degenerative joint disease. There are three manifestations of CPPD that may occur alone or together:

a: Crystal Induced Acute Synovitis.These acute attacks, also known as pseudogout, may last one day to several weeks. The patient may find relief from colchicine.

b: Cartilage Calcification. Calcification of the cartilage, or chondrocalcinosis, is classic for CPPD though it may be seen with other conditions such as hyperparathyroidism, hemochromatosis, acromegaly, gout, and Wilson's disease. Some people may have asymptomatic chondrocalcinosis that is never associated with CPPD arthropathy. The crystals may deposit in fibrocartilage such as in the meniscus of the knee, triangular fibrocartilage of the wrist, acetabral labra, symphysis pubis, or anulus of the intervertebral disc. These deposits look thick, and irregular. When deposits are in hyaline cartilage they appear thin, linear, and they parallel the cortical surface of the bone. Calcification may also occur in the synovium where it may resemble synovial osteochondromatosis. Capsular calcifications are linear and fine in their appearance. When deposits occur in tendons, bursae, or ligaments, they resemble calcium hydroxyapatite crystal deposition disease (HADD) though they should appear more linear and thin. Many times, however, patients do have a mixed crystal arthropathy with both calcium pyrophosphate and calcium hydroxyapaptite crystal deposition.

Joint Abnormalities The degenerative changes seen with CPPD are termed pyrophosphate arthropathy. Though these changes are similar in appearance to degenerative joint disease there are some distinct differences. The distribution of CPPD arthropathy is at sights not common for DJD, including the wrist, elbow, and shoulder. When CPPD does affect joints, it produces a pattern of degeneration unlike DJD.

In the knee, CPPD will produce degenerative changes at the patellofemoral joint and in the medial and lateral joint spaces. DJD typically affects the medial joint space, as this is the weightbearing portion of the joint. Advanced patellofemoral joint space narrowing may result in a pressure erosion of the anterior surface of the distal femur. Pyrophosphate arthropathy produces more prominent subchondral cysts, subchondral collapse, and loose bodies than are seen with DJD. The osteophyte formation is variable.

In the wrist, CPPD produces calcification of the triangular fibrocartilage, and the hyaline cartilage of the radiocarpal and midcarpal joints. The radiocarpal joint is involved most often, especially the scapholunate articulation. Proximal displacement of the scaphoid and distal displacement of the lunate result in a classic "stepladder" appearance. Disruption of the scapholunate ligament results in widening of the distance between the two bones.

In the shoulder, CPPD produces glenohumeral joint space narrowing, capsular, tendinous, and bursal calcifications. Again, large subchondral cyst formation and subchondral sclerosis are common.


Click here to continue to self assessment


Introduction to Unknown Cases

Page 1 2 3




Questions? Comments? Send e-mail to Northwestern Health Sciences University Web Coordinator.
2001 Northwestern Health Sciences University/ www.nwhealth.edu - All Rights Reserved
Copyright Information