Study of 1,361 Patients Finds Knee Osteoarthritis Follows 1 Biological Continuum

2 articles · Updated · Nature.com · Jun 2

Proteomic analysis of synovial fluid from 1,361 people with knee osteoarthritis found no distinct molecular endotypes, instead placing patients along a single biological continuum.
Unsupervised clustering showed an apparent 2-cluster pattern was driven by intracellular protein contamination; after adjustment, the separation disappeared and epithelial-mesenchymal transition emerged as the dominant shared pathway.
Structural disease severity showed much stronger molecular signals than pain: 3,815 proteins were linked to advanced radiographic OA, with EMT, complement and angiogenesis repeatedly enriched.
Obesity and sex did not create separate disease types, but they did shift pathway intensity—complement and coagulation were stronger in obese patients, while angiogenesis and coagulation were more prominent in males.
The findings suggest future OA trials may work better by stratifying patients along pathway activity rather than treating knee osteoarthritis as several distinct molecular diseases.

Sources

Is osteoarthritis one disease, or did the technology in this landmark study miss crucial evidence of different types?

If biology doesn't explain osteoarthritis pain, what is the true source of a patient's suffering?

With key osteoarthritis pathways now known, can a drug that finally halts the disease be far behind?

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