Pain sensitization linked to increased risk for persistent knee pain

Becoming more sensitive to pain, or pain sensitization, is an important risk factor for developing persistent knee pain in osteoarthritis (OA), according to a new study by researchers from the Université de Montréal (UdeM) School of Rehabilitation and Hôpital Maisonneuve Rosemont Research Centre (CRHMR) in collaboration with researchers at Boston University School of Medicine (BUSM). These findings have just been published in the journal Arthritis and Rheumatology.

OA is a common cause of pain and altered joint function, affecting 302 million adults worldwide. It can lead to chronic disability frequently in the knee joint. Past research suggests that a number of different factors outside of structural pathology may contribute to pain experienced in patients with OA.

"Understanding the factors that contribute to the development of persistent pain is critical in improving our ability to prevent its onset and the transition to more persistent pain', said Lisa Carlesso BSc.PT. PhD, assistant professor School of Rehabilitation UdeM and scientist CRHMR.

Researchers analyzed data from a multicenter OA study that followed 852 adults (ages 50-79) with or at risk of knee OA but who were free of persistent knee pain at the beginning of the study. Sociodemographic data, pain sensitization measurements, as well as risk factors traditionally associated with knee pain such as psychological factors, widespread pain and poor sleep were collected on the participants who then were followed for development of persistent knee pain over two years.

The researchers used the above risk factors and pain sensitization data to identify four distinct subgroups called pain susceptibility phenotypes (PSPs). The authors found these PSPs were primarily characterized by varying degrees of pain sensitization. The PSP with the highest degree of sensitization had the highest risk of developing persistent knee pain. Female gender, non-Caucasian race and age 65+ were significant sociodemographic predictors of being a member of the PSP with the highest degree of sensitization.

The researchers believe identifying these PSPs is an important step in understanding the complex pathology of knee osteoarthritis. "Our findings suggest that therapy aimed at prevention or improvement of pain sensitization may be a novel approach to preventing persistent knee pain," explained author Tuhina Neogi, MD, PhD, professor of medicine and epidemiology at BUSM and BU School of Public Health. "Preventing pain is crucial to improving quality of life and function in patients who suffer from OA."