Figure. Anteroposterior radiograph of the left knee.
A 72-year-old woman presents to the office with a history of pain in her left knee that has been present for several years. Over the past month, she notes that the pain has worsened. She denies experiencing recent injury or having any precipitating event. On physical examination, she has moderate effusion, full range of motion, and no crepitus with repetitive knee flexion. Anteroposterior radiograph of the left knee is obtained (Figure).
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The patient’s imaging shows calcium pyrophosphate dihydrate crystal deposition (CPPD) throughout the medial and lateral menisci, which is indicative of chondrocalcinosis or pseudogout. Pseudogout is the most common crystalline arthropathy in the knee and is seen in up to 10% of patients aged 50 years and older.1
CPPD can form on meniscal tissue or, less commonly, on the articular cartilage of the knee. Non-urate crystals in the knee can create synovitis and cause gout-like attacks. Unlike gout or monosodium urate crystal deposition, no medications are available that can decrease the crystal load associated with CPPD arthropathy.
Chondrocalcinosis is frequently asymptomatic.1 Compared with gouty attacks, pseudogout attacks tend to take longer to reach peak pain intensity and are slower to resolve with treatment. The diagnosis of CPPD arthropathy is made with a synovial fluid analysis, which will also help rule out gout and septic arthritis. Chondrocalcinosis can also cause a higher rate of false-positive meniscus tears on magnetic resonance imaging.1
The most common treatment for chondrocalcinosis is joint aspiration with an intra-articular corticosteroid injection, which can be very effective in reducing pain.1,2
Dagan Cloutier, MPAS, PA-C, practices in a multispecialty orthopedic group in the southern New Hampshire region and is editor-in-chief of the Journal of Orthopedics for Physician Assistants.
1. Kaushik S, Erickson JK, Palmer WE, Winalski CS, Kilpatrick J, Weissman BN. Effect of chondrocalcinosis on the MR imaging of knee menisci. AJR Am J Roentgenol. 2001;177(4): 905-909.
2. MacMullan P, McCarthy G. Treatment and management of pseudogout: insights for the clinician.Ther Adv Musculoskelet Dis. 2012;4(2):121-131.