Association between vitamin D concentrations and knee pain in patients with osteoarthritis

OBJECTIVES: Osteoarthritis (OA) and vitamin D deficiency are common health conditions in older people. Whether vitamin D concentration is associated with knee OA is controversial. In this study, we aimed to determine the association between serum concentrations of vitamin D and osteoarthritic knee pain. SUBJECTS AND METHODS: Vitamin D concentrations were measured with the 25 hydroxyvitamin D test in patients presenting with clinical symptoms of primary knee osteoarthritis. Osteoarthritis was graded on the Kellgren-Lawrence grading scale from anteroposterior and lateral radiographs. Height, weight, and body mass index (BMI) were recorded. Patients completed a 10-cm visual analogue scale (VAS) for indicating pain and the Western Ontario and McMaster Universities Arthritis Index (WOMAC). Vitamin D concentration was defined as severely deficient (<10 ng/mL), insufficient (10 to 19 ng/mL), or normal (20 to 50 ng/mL). RESULTS: Of 149 patients (133 women), the mean age was 63.6 years. Mean vitamin D concentration was 11.53 ng/mL, and 90% patients were vitamin D deficient. Mean WOMAC score was 57.2, and VAS pain score was 7.5. Kellgren-Lawrence grade was 2 for 10 patients, grade 3 for 61, and grade 4 for 88. Mean BMI was 33.4. Mean values of VAS, WOMAC, and BMI did not differ by vitamin D status. CONCLUSION: Serum vitamin D concentration is not associated with knee pain in patients with osteoarthritis.