Vitamin D status and pain sensitization in knee osteoarthritis: a critical review of the literature.

Diagnostic imaging of disease severity has been found thus far to be a relatively modest predictor of knee osteoarthritis (OA) pain and disability, suggesting that other factors likely contribute to clinical symptoms in this condition. Recent evidence suggests that sensitization of the peripheral and central pathways that process nociceptive information (i.e., pain sensitization) is an important contributor to knee OA clinical symptoms. Furthermore, low levels of vitamin D have been found to be associated with the presence of pain sensitization, as well as the overall experience of clinical pain severity in knee OA. African-Americans with knee OA may be at increased risk for poor clinical outcomes given evidence of lower vitamin D levels as well as greater pain sensitization compared with non-Hispanic whites. Whether vitamin D supplementation is effective for alleviating knee OA clinical symptoms is an important topic to be addressed in future research with racially diverse samples that include sufficient numbers of African-Americans.