Knee Pain, Not Radiographic Osteoarthritis, Key to Widespread Pain

Knee pain severity is significantly associated with the development of widespread pain independent of structural pathology.

Researchers explored the longitudinal relationship between knee pain, radiographic osteoarthritis, symptomatic knee osteoarthritis, and knee pain severity using data from the Multicenter Osteoarthritis Study.

Led by Lisa C. Carlesso, BScPT, PhD, of the University of Montreal in Canada, the study team examined these relationships as a way to mitigate the development of widespread pain via earlier, more targeted interventions.

“These findings highlight the importance of pain symptomatology as an important factor that can contribute to the onset of widespread pain, suggesting a possible role for sensitization and the importance of adequately managing pain symptoms,” wrote de Carlesso and colleagues.

Musculoskeletal pain disorders can affect joints in isolation, in regions, or throughout the body. Widespread pain is often reported in persons with osteoarthritis, but the etiology is not well understood. Associated risk factors include older age, multi-joint osteoarthritis, cognitive decline, and poor sleep.

To date, few longitudinal studies have examined the time horizon of knee osteoarthritis and its relationship to widespread pain. Some hypothesize that persistent nociceptive peripheral input may result in widespread pain due to sensitization of the CNS. This hypothesis suggests that peripheral structural pain pathology, like what is seen in knee osteoarthritis, would contribute to the progression to widespread pain.

The study was published online May 8 in Arthritis Care & Research.

The study

The parent Multicenter Osteoarthritis Study was a longitudinal cohort study of 3026 adults aged 50 to 79 years recruited from Birmingham, Alabama, and Iowa City, Iowa. Participants had or were at risk for knee osteoarthritis. Participants in the parent study were assessed at baseline, 30 months, 60 months, and 84 months. The present study was restricted to 1129 participants who attended the 60-month visit and followed up at the 84-month visit. Any participant who had a total knee replacement by 60 months was excluded.

The primary outcome, widespread knee pain, was defined as the presence of pain above and below the waist, on both the left and right sides of the body, and axially using a validated standard homunculus. Given the focus of the study, pain in the knee was excluded from the widespread pain definition. Also assessed were frequent knee pain, radiographic osteoarthritis, symptomatic osteoarthritis, and knee pain severity.

The major finding was the association between widespread pain and baseline knee pain severity. That is, each point higher on the 0 to 20 Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC) pain subscale was associated with a 14% increased risk of incident widespread pain (adjusted OR per subscale unit increase 1.11 [95% CI 1.05–1.17]; P<0.001; crude OR 1.14).

“These findings support the need for further exploration of mechanism-based management of pain as a disease unto itself in order to avoid negative consequences of pain that goes untreated,” concluded the study team.

Disclosures:

The Multicenter Osteoarthritis Study was supported by the NIH.

References:

Carlesso, L. C., Segal, N. A., Curtis, J. R, et al. “Knee Pain and Structural Damage as Risk Factors for Incident Widespread Pain: Data From the Multicenter Osteoarthritis Study.” Arthritis Care Res (Hoboken). 2017;69:826-832. doi: 10.1002/acr.23086. Epub 2017 May 8.