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Researchers from the Universities of Oxford, Nottingham and Zhejiang have found that the precise measurement of joint lining inflammation corresponds well with osteoarthritic knee pain. It's even better when size of the joint is taken into consideration and this should be considered when examining treatment effects in clinical trials.

A knee

In a new study, published in the Journal of Rheumatology, the researchers found that measures of synovial tissue volume (STV), measured on magnetic resonance imaging (MRI), were strongly and linearly associated with joint pain in knee OA.

Synovitis, or joint inflammation, is common in painful knee OA and has been shown to be a strong predictor of disease progression. As an important marker of disease and, due to the known relationship with pain, synovitis has frequently been used as a marker of response in clinical trials of anti-inflammatories. However, optimal measurement of synovitis is unclear. 

“Currently, there are no disease modifying anti-rheumatic drugs (DMARDs) for knee OA. This in turn has created a great need to identify new structural targets for clinical trials. The way in which we define and measure these structures is critical when trying to determine if they have a positive effect (e.g. improve symptoms),” explained Thomas Perry, first author and Postdoctoral Research Fellow in Sport, Exercise and Osteoarthritis at NDORMS.

“It is possible that currently used measures are not sensitive enough to detect clinically important changes during clinical trials.”

To test the theory, the team examined the relationship between measures of synovitis (inflammation of the joint) and knee joint symptoms. Using MRI scanning, STV seen across the entire knee joint was assessed, and synovitis located at specific regions of the knee joint was also evaluated – these measures are known as absolute volumes. Within the same study, the researchers also measured the size of the knee joint to calculate relative values.

They found that relative volumes of synovitis were much more strongly associated with pain compared to the absolute volume measures.

“What this indicates is that precise segmentation of knee inflammation on MRI which takes into consideration the size of the bones forming the knee joint is so far the most precise measure linked with the knee pain. These new measures of synovitis can help us to understand how different treatments work in different patients with knee pain.”

‘Joint lining inflammation is an integral part of knee arthritis development, but it is difficult to measure precisely. It is more complicated when you take into consideration that knee joint sizes are different. An average 75-year-old woman has smaller joints than an average rugby player. Here, we combined for the first time the precise and reliable methods of measuring this inflammation and took into account differences in bone size between individuals. This new method explains exceptionally well the arthritic pain and provides us with a precise tool to measure the effects of our interventions in future trials.’ explained Dr Stefan Kluzek, senior author and the NUH deputy director of Versus Arthritis Centre of Excellence in Sport, Exercise and Osteoarthritis.

This work was funded by Versus Arthritis Centre for Sport, Exercise and Osteoarthritis.