One of the most persistent puzzles in osteoarthritis: X-rays of the knee correspond poorly with how much a person actually hurts.
Two people can have near-identical joint damage on imaging. One walks comfortably. The other is in constant pain and has stopped going out. The X-ray does not explain the difference.
A 2026 study in ACR Open Rheumatology from UF researchers approached this from an angle that has not been fully explored: what if the difference lies in the interaction between how the nervous system processes pain and how the body moves?
What they did. The team — Alisa Johnson, B.C. Murillo, and Yenisel Cruz-Almeida — grouped people with symptomatic knee osteoarthritis by their pain sensitivity profiles, a way of characterizing how responsive an individual’s nervous system is to painful input. They then examined how those profiles related to muscle biomechanics and to the pain participants reported clinically.
What they found. The profiles were associated with both. How a person’s nervous system handled pain tracked with how their muscles behaved and with how much pain they lived with.
Why it matters. Osteoarthritis is usually treated as a structural problem — worn cartilage, narrowed joint space — addressed with structural solutions. This work supports a different framing: the same structural damage lands differently depending on the nervous system receiving it, and on how the person moves as a result.
If that holds up, “knee osteoarthritis” may need subtyping before treatment rather than after. A patient whose pain is driven largely by central sensitization plausibly needs something different from a patient whose pain tracks joint loading — even when their X-rays are indistinguishable.
This is one study, and it establishes association rather than cause. But it is a concrete step toward answering a question patients have been asking their clinicians for decades: why does mine hurt so much more than theirs?
What we study:
- Pain and Aging
- Chronic Pain Risk Factors
- Pain and the Brain
- Musculoskeletal Pain
- Pain and Exercise
- Non-Medical Treatment of Pain
Prefer to talk to a person? Call 352-273-5967 or email PRICE-CTSI@ufl.edu.
UF Study ID IRB201400126
References
- Johnson AJ, Murillo BC, Cruz-Almeida Y. Pain Sensitivity Profiles Are Associated With Muscle Biomechanics and Clinical Pain in Persons With Symptomatic Knee Osteoarthritis. ACR Open Rheumatol. 2026 Aug;8(8). https://doi.org/10.1002/acr2.90118
- PRICE Research Registry recruitment materials, UF Study ID IRB201400126. IRB-approved; supplied by site owner. https://is.gd/PRICE