ACP Journal Club: supplementation with vitamin D did not reduce cartilage volume loss or pain in knee osteoarthritis.

Patients: 146 patients ≥ 45 years of age (mean age 62 y, 61% women) with symptomatic knee OA (American College of Rheumatology criteria: long-term knee pain and ≥ 1 osteophyte on knee radiograph [equivalent to Kellgren-Lawrence grade 2]), mild or worse weight-bearing pain (Western Ontario and McMaster Universities [WOMAC] pain subscale), and pain or discomfort referable to the knee joint. Exclusion criteria included use of vitamin D supplement > 800 IU/d, serum calcium level > 10.5 mg/dL, hypercalciuria (spot urine calcium–creatinine ratio > 0.4), use of supplements or medications with possible effects on cartilage (e.g., glucosamine), intraarticular therapies within 3 months, use of long-term oral corticosteroids, lymphoma, sarcoidosis, tuberculosis, hyperparathyroidism, malabsorption disorders, glomerular filtration rate < 30 mL/min/1.73 m2, or inflammatory joint disease.