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Idiopathic OA of the Knee

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Clinical and laboratory

Clinical and radiographic

Clinical

Knee pain

Knee pain

Knee pain

+ at least 5 of 9:

+ at least 1 of 3:

+ at least 3 of 6:

   - Age > 50 years

    - Age > 50 years

   - Age > 50 years

    - Stiffness < 30 minutes

    - Stiffness < 30 minutes

    - Stiffness < 30 minutes

    - Crepitus

    - Crepitus

    - Crepitus

    - Bony Tenderness

+ Osteophytes

    - Bony Tenderness

    - Bony enlargement

    - Bony enlargement

    - No palpable warmth

    - No palpable warmth

    - ESR <40 mm/hour

    - RF <1:40

    - SF OA

92% sensitive

91% sensitive

95% sensitive

75% specific

86% specific

69% specific

* ESR = erythrocyte sedimentation rate (Westergren); RF = rheumatoid factor; SF OA = synovial fluid signs of OA (clear, viscous, or white blood cell count <2,000/mm3).

† Alternative for the clinical category would be 4 of 6, which is 84% sensitive and 89% specific.

R. Altman, E. Asch, D. Bloch, G. Bole, D. Borenstein, K. Brandt, et al. The American College of Rheumatology criteria for the classification and reporting of osteoarthritis of the knee. Arthritis Rheum 1986;29:1039--1049.