The following knee x-rays are from a 70 year old patient with left knee pain and swelling. What can you note in the x-rays?

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The AP knee x-ray shows linear calcification in the menisci; this is chondrocalcinosis. The lateral view shows minimal effusion.

Chondrocalcinosis (pseudogout) is acute arthritis caused mostly by calcium pyrophosphate crystal deposition in the articular or fibro cartilage. It usually affects the knee or wrist joint and can mimic gout and septic arthritis.

It can occur in the healthy elderly population or in association with metabolic diseases such as hemochromatosis, hyperparathyroidism, hypothyroidism, hypomagnesaemia and Wilson’s disease.

Synovial fluid analysis in pseudogout shows positively birefringent rhomboid shaped crystals whereas in gout, the crystals are negatively birefringent and needle shaped.

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