Criteria

Diagnostic criteria and categories for CPP arthritis[14][15]

1. Demonstration of CPP crystals in tissues or synovial fluid by definitive means, such as x-ray diffraction or chemical analysis.

2A. Identification of CPP crystals by morphological analysis using compensated polarising light microscopy.

2B. Typical calcifications on x-rays (cartilage calcification); heavy punctuate or linear calcifications in fibro-cartilage, articular (hyaline) cartilage, or joint capsules.

3A. Acute arthritis, especially of the knee or other large joints.

3B. Chronic arthritis of the knee, hip, wrist, elbow, shoulder, or metacarpophalangeals, particularly if accompanied by acute exacerbations, and if characterised by:

  • Involvement of uncommon sites for primary osteoarthritis

  • Radiographical appearance, including severe patellofemoral involvement

  • Subchondral cyst formation

  • Severe progressive joint degeneration with bony collapse

  • Variable and inconsistent osteophyte formation

  • Tendon calcifications, particularly of the Achilles, triceps, and obturator tendons

  • Axial skeletal involvement with subchondral cysts, disc calcification, and vacuum disc phenomena, as well as sacroiliac joint involvement.

Categories

  • Definite: criterion 1 or 2A and 2B

  • Probable: criterion 2A or 2B

  • Possible: criterion 3A or 3B.

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