Are 25(OH)D levels related to the severity of knee osteoarthritis and function?

To investigate the effect of 25-hydroxyvitamin D [25(OH)D] in Kuwaiti patients with primary knee osteoarthritis (OA) and to assess its relation with radiological grading and functional status.

In this cross-sectional study, 25(OH)D was measured using radioimmunoassay in 99 patients [90 women and 9 men; mean age 56.5 ± 9.1 years (range: 36-80)] with clinical and radiological findings of primary knee OA. X-ray grading using the Kellgren-Lawrence grading scale and the Osteoarthritis Research Society International (OARSI) Atlas grading scale and functional assessments using Lequesne's indices were evaluated in relation to the 25(OH)D level. Other variables studied were age at onset of symptoms, body mass index and duration of disease.

The age of the patients at the onset and the duration of disease were 51.58 ± 7.14 and 3.88 ± 2.51 years, respectively. Mean scoring for functional assessment was 10.31 ± 4.35 and mean Kellgren-Lawrence radiological grading was 2.43 ± 0.85. Radiological finding according to the OARSI Atlas revealed joint space narrowing of grades 2-3 in 87 (87.9%) patients and the presence of osteophytes in 55 (55.6%) patients. The mean value of 25(OH)D level was 11.4 ± 6.07 ng/ml. Of the 99 patients, 92 (92.9%) were vitamin D deficient. Comparison of 25(OH)D levels to radiological findings and different functional classes showed no significant association.

Most of our patients had vitamin D deficiency, but the level of 25(OH)D was not related to the severity of the knee X-ray grading or to the functional assessment in our patients with primary knee OA.