BOSTON—Inflammation related to synovitis or effusion may drive increased sensitization in knee osteoarthritis, according to research presented at the 2014 American College of Rheumatology Annual Meeting.
“It is widely recognized that the level of pain patients experience is not always what one would expect based upon what is seen on their x-rays,” said lead author Tuhina Neogi, MD, PhD, of Boston University School of Medicine.
Tuhina Neogi, MD, PhD
Using data from the Multicenter Osteoarthritis Study (MOST), researchers looked at test results obtained from 1,111 subjects with or at risk of knee osteoarthritis, including x-rays, magnetic resonance imaging scans (MRI), and standardized somatosensory evaluations of two measures that give insights into the presence of sensitization. These measures were obtained at the knee at baseline and again two years later. The mean age of the subjects in the study was 66.9. The mean body mass index was 29.7, and 62% were female.
The researchers looked at how synovitis, effusion, and bone marrow lesions (BMLs) seen at the baseline assessment might be related to the new development of temporal summation in the same knee two years later among those who did not show signs of it at the baseline visit. They also assessed changes in pressure pain thresholds levels in the same knee between baseline and the visit two years later in all the subjects.
A total of 22.6% developed incident temporal summation by the two-year study visit. Between the baseline and two-year visit, changes in the pressure pain thresholds levels ranged from -7.35 to 7.15 kg/cm2. Synovitis was associated with significant decreases in pressure pain thresholds. Effusion was significantly associated with incident temporal summation. Bone marrow lesions presence or burden was not associated with temporal summation or change in pressure pain thresholds.
The study’s authors concluded that inflammation, such as that associated with synovitis or effusion, may drive sensitization in knee osteoarthritis, while bone marrow lesions do not appear to do so. Furthermore, researchers suggested that early targeting of inflammation in knee osteoarthritis may prevent sensitization and helping to reduce pain severity in people with knee osteoarthritis.
“This is the first such study in knee osteoarthritis to obtain sensitization measures at more than one time-point in such a large number of individuals, providing insights for the first time into how sensitization may develop or change over time in this disease,” said Dr. Neogi.