Identifying different groups of people with knee osteoarthritis
Wyatt LA, Moreton BJ, Mapp PI, Wilson D, Hill R, Ferguson E, Scammell BE, Walsh DA. Histopathological subgroups in knee osteoarthritis. Osteoarthritis and Cartliage. April 2016 Volume 24, Supplement 1, Page S386. http://www.oarsijournal.com/article/S1063-4584(16)00712-3/fulltext
Key findings and importance of study
Different people with knee osteoarthritis (OA) often have different symptoms and joint structural changes and also respond differently to treatment. We show that patients with OA can be classified into 3 groups based on differences in changes in the joint. Subgrouping people with OA may allow for more effective personalised treatments to reduce pain and slow down disease progression.
Knee OA is a variable disease, people with the OA experience different levels of pain and structural changes within the joint. Currently, all patients are all offered similar treatments, which may be more beneficial in some patients compared to others due to the type of OA they have. Better ways to characterise people with OA based on structural changes within the joint should lead to the development of more personalised medicines.
We wanted to know if we can identify different types of patients with OA based on the level of microscopic cartilage and bone damage, as well as degree of inflammation in the synovium (soft tissue lining the knee joint).
How the study was carried out
Knee tissues (cartilage, bone and synovium) were collected from two groups; post-mortem donors, and people who had a knee replacement for painful OA. Microscopic differences in the tissues were compared between the groups. A statistical tool called latent class analysis was used to subgroup people with OA based on the severity of changes in the cartilage, bone and synovium.
What the study found
Latent class analysis identified three different groups of people with OA. One group had mild structural changes and no inflammation; the other two groups had more
severe structural changes to their cartilage and bone tissues and differed by the severity of inflammation in their joint. Knee replacement patients with painful OA were allocated to each of the 3 groups. The link between structural changes and pain in OA is complex. Future work should test the idea that people who have knee replacement but have little structural change may be experiencing pain due to changes in the brain and spinal cord (rather than entirely from the knee).
Significance of the study to arthritis research
Better understanding of the structural changes in the knee that develop during OA and how they differ between different types of people with OA should lead to the development of more personalised and effective treatments.