Rheumatoid Arthritis and Hypermobility: When Familiar Joint Pain Changes

If you live with hypermobility, joint pain may already be familiar. You may know which knee complains after a long walk, which ankle becomes unstable when you are tired, or how your hands feel after too much repetitive activity. Over time, you learn the patterns of your own body, including what tends to trigger symptoms and what usually helps them settle.

That familiarity can be useful. But it can also make a new problem harder to recognise.

What happens if a joint that normally hurts after activity begins staying swollen the next morning? What if stiffness starts lasting after you wake up, several joints change around the same time, or pain begins behaving differently from the pattern you have known for years?

This is where rheumatoid arthritis and hypermobility become an interesting combination to examine. The question is not simply whether the two conditions can occur together. They can. The more useful question is what happens when an inflammatory joint disease develops in someone whose joints and connective tissues may already produce pain, instability and altered movement.

Recent research gives us several reasons to look more closely at that overlap. A large hEDS registry has reported rheumatoid arthritis more frequently than the general-population estimate used by the researchers. Meanwhile, research into RA is revealing a joint environment shaped not only by immune activity, but also by the behaviour of synovial cells, metabolism, connective tissue, mechanical forces and mast cells.

To understand why those findings might matter, it helps to begin inside the rheumatoid joint itself.

What actually happens in rheumatoid arthritis?

Rheumatoid arthritis, or RA, is a chronic systemic inflammatory disease. It can affect different parts of the body, but its effects on joints are usually what people recognise first: pain, swelling, warmth, stiffness and, over time, damage to joint structures.

RA affects millions of people worldwide and is considerably more common in women. The Global Burden of Disease study published in The Lancet Rheumatology estimated that around 17.6 million people were living with RA globally in 2020, with age-standardised prevalence approximately 2.45 times higher in women than men. The reasons for this difference are still being investigated and are likely to involve interactions between biological sex, hormones, genetics, immune regulation and environmental factors.

RA is classified as an autoimmune disease, which is often simplified as the immune system mistakenly attacking the body's own tissues. That is a useful starting point, but it can make the joint sound like a passive structure that simply becomes the target of an immune attack.

The biology is more dynamic than that.

A joint is living tissue. The synovium that lines it contains different types of cells, blood vessels and extracellular matrix, all communicating within a constantly changing chemical and physical environment. During RA, immune activity changes that environment. Synovial cells respond, inflammatory signals increase, the tissue itself changes, and these processes can begin reinforcing one another. This helps explain how inflammation within a joint can become persistent.

Researchers are therefore increasingly interested in the whole environment in which rheumatoid inflammation takes place. Genetic susceptibility and environmental exposures remain important, as does immune regulation, but metabolism, the behaviour of synovial fibroblasts, changes in the extracellular matrix and even the mechanical properties of the tissue are now part of the picture.

A 2026 review in Frontiers in Immunology describes these processes as interconnected, with inflammation, metabolism and mechanical signalling influencing one another within rheumatoid tissues.

That wider view of RA becomes particularly relevant when the person developing it already has joints that may move, load and experience strain differently because of hypermobility.

But before we get to the biology of that overlap, there is a more immediate problem: recognising that something new is happening in the first place.

When joint pain is already part of your normal

RA is commonly associated with the hands and wrists, but it can also affect the feet, ankles, knees, elbows, shoulders and other joints. The knees are particularly worth mentioning in the context of hypermobility because knee pain is already familiar to many hypermobile people. In a study of early RA, the knees were the most commonly swollen large joints at presentation. Read the study in PLOS One.

The difficulty is that a list of affected joints does not tell you very much when those joints already hurt.

Someone with longstanding hypermobility may have years of knee pain associated with walking or standing, ankle problems related to instability, or hand pain following repetitive use. If a new inflammatory disease develops, the location of the pain may therefore be less informative than the way the symptoms begin to behave.

A knee may still be the same knee that has troubled you for years, but now it remains swollen after the activity that triggered it has ended. Hands that normally become sore with use may start feeling stiff after a night's rest. A familiar joint may feel warm. Several joints may begin changing during the same period rather than following their usual individual patterns.

This distinction matters because the first explanation for new pain is often the one that already makes sense.

When an existing diagnosis shapes the interpretation of new symptoms, it is sometimes described as diagnostic overshadowing. Research into delays in RA diagnosis has found that early symptoms can be attributed to injuries, ageing and other musculoskeletal explanations before inflammatory arthritis is recognised. Qualitative research into delays in RA diagnosis has documented these experiences.

Hypermobility adds another layer because the existing explanation is often perfectly reasonable. Hypermobility can cause significant musculoskeletal pain and dysfunction. A painful knee in a hypermobile person may indeed be related to instability, altered loading, tendon overload or previous injury.

The challenge is recognising when that familiar explanation no longer accounts for the whole picture.

For that reason, someone who already lives with joint pain may gain more useful information by asking "What has changed?" rather than simply "Where does it hurt?"

That change in pattern also becomes important when the usual RA blood tests do not provide a straightforward answer.

When the blood tests do not tell the whole story

Rheumatoid factor and anti-CCP antibodies are useful pieces of the RA diagnostic picture, alongside inflammatory markers such as CRP and ESR. But RA is diagnosed by bringing different types of information together: the history of the symptoms, which joints are involved, what examination reveals, blood results and, in some cases, imaging.

Some people with RA do not have the standard RA-associated antibodies. This is generally described as seronegative RA.

A 2025 article in Nature Reviews Rheumatology discusses how seronegative RA can remain under-recognised and how this can contribute to delays in diagnosis and treatment.

This is where the history of how a person's symptoms have changed becomes particularly valuable. A blood result is one piece of information taken at a particular point in time. The person living in the body can provide another kind of information: what this joint normally does, what used to trigger the symptoms, how long they usually lasted, and what is different now.

Imaging can add another perspective. Ultrasound and MRI allow clinicians to examine what is happening within joints and surrounding tissues rather than relying on symptoms or blood markers alone. A 2025 expert review describes their growing role in early and seronegative RA and in distinguishing RA from other conditions with similar presentations.

For someone with hypermobility, this combination of history, examination, blood tests and imaging can be especially important because mechanical and inflammatory problems do not have to be mutually exclusive. A person can have joint instability and inflammatory arthritis. Tendon overload can exist alongside synovitis. Different joints may hurt for different reasons, and more than one process may contribute to symptoms in the same area.

Once we recognise that the two conditions can overlap clinically, another question follows naturally: how often are they actually appearing together?

Are RA and hEDS appearing together more often?

A 2026 study using the DICE EDS & HSD Global Registry gives us an interesting reason to look more closely at the overlap between hEDS and inflammatory disease.

Among participants with hEDS, 4.86% reported rheumatoid arthritis, compared with the 0.21% general-population estimate used by the researchers.

RA was not the only inflammatory or immune-related condition appearing in the cohort. Inflammatory bowel disease was reported by 10.30% of participants, Hashimoto's thyroiditis by 9.06%, psoriasis and/or psoriatic arthritis by 5.64%, Sjögren's syndrome by 5.13%, and MCAS by 30.09%.

Read the DICE Registry study in the Journal of Rare Diseases.

Because the registry was self-selected and diagnoses were self-reported, these percentages should be understood as findings within this hEDS cohort rather than prevalence estimates for everyone with hEDS.

What makes the findings interesting is that RA appears within a broader pattern of inflammatory and immune-related conditions. That gives researchers a reason to look more closely at whether particular groups of people with hEDS have a greater susceptibility to inflammatory disease, and what might be contributing to that overlap.

For RA in particular, this leads us back to the joint itself. If rheumatoid inflammation develops in someone whose connective tissue and joint mechanics are already different, could that existing mechanical environment influence what happens inside the joint?

That question becomes particularly interesting when we look at where RA research is heading.

A joint is both biological and mechanical

We usually separate mechanical and inflammatory joint problems when talking about pain. One is described in terms of movement, instability, loading and strain; the other in terms of immune cells and inflammation.

Inside a living joint, that separation is much less tidy.

Every movement places forces through cartilage, connective tissue, synovium and surrounding structures. Cells within those tissues experience pressure, stretch, tension and changes in tissue stiffness. Remarkably, they can sense those physical conditions and change their behaviour in response.

This ability to translate a physical force into a cellular response is called mechanotransduction.

It matters because cells do not behave identically regardless of their physical surroundings. Mechanical signals can affect how cells communicate, which genes they activate, how they interact with the extracellular matrix and how tissues respond to injury and inflammation.

This is becoming an important area of RA research.

The 2026 review on RA pathogenesis describes a feedback relationship between inflammation, extracellular-matrix changes, tissue stiffness and synovial fibroblasts. Inflammation changes the tissue around these cells. As that environment changes, the physical signals reaching the cells change too. The cells respond to those signals, potentially contributing to further changes in the inflammatory environment.

In other words, the mechanics and the inflammation are communicating.

That gives us a new way to think about a hypermobile joint.

A joint that moves through a different range, experiences instability or repeatedly loads surrounding tissues in an altered way has its own mechanical environment. If inflammatory arthritis develops in that joint, researchers can begin asking how the pre-existing mechanical conditions interact with the inflammatory processes now taking place there.

This is a more specific question than asking whether hypermobility "causes inflammation." It asks how physical forces influence cells once inflammation, genetic susceptibility and immune activity are already part of the system.

And when we start looking at the cells responding to that environment, another part of the original registry finding becomes relevant.

Mast cells connect another part of the picture

Mast cells are immune cells that live within connective tissues throughout the body. Many people associate them mainly with allergic reactions, but their biology is considerably broader. They sit close to blood vessels and nerves and can release mediators that influence vascular changes, pain signalling, immune responses and surrounding cells.

They are also present in the synovium.

A 2024 study in Nature Communications examined mast cells directly in rheumatoid synovial tissue. Researchers found more mast cells in RA synovium than in osteoarthritis, and their frequency was associated with inflammatory markers. The rheumatoid joint environment also appeared capable of shifting mast cells towards a more activated state.

This is interesting in its own right because it places mast cells within the network of cells responding to the rheumatoid joint environment.

It becomes even more interesting alongside the DICE registry, where 30.09% of participants with hEDS reported MCAS.

The two findings invite a broader question about mast-cell biology in people who experience both connective-tissue differences and inflammatory disease. Mast cells live in the very tissues where mechanical forces, injury signals and inflammatory mediators are constantly being exchanged. Their behaviour is shaped by the environment around them, while the mediators they release can alter that environment in return.

This creates another possible point of interaction between tissue biology and inflammation. Researchers can investigate how mast cells respond to mechanical stress, whether repeated tissue strain changes local signalling, and whether particular patterns of mast-cell activity influence inflammatory processes within susceptible joints.

Seen this way, mechanics, inflammation and mast cells are not three unrelated topics added to the same article. They are different parts of the same biological environment.

And that brings us back to the person whose knee has suddenly started behaving differently.

What does this mean when you already live with hypermobility?

Research into mechanisms takes time, and many of these questions will require much more investigation. But there is something useful we can already take from the clinical side of this overlap.

When pain has been part of your life for a long time, pain alone may contain less information than change.

You know your baseline better than anyone seeing you for the first time. You may know that your knee usually aches after walking but settles overnight, that your fingers hurt after repetitive work but are fine in the morning, or that an unstable ankle flares in a predictable way after being overloaded.

That history gives you something to compare new symptoms against.

Persistent swelling where you previously had pain alone, warmth that is new for that joint, longer stiffness after waking or resting, several joints changing together, or a noticeable change in function can all help describe how the current problem differs from the one you already know.

This is also a more useful way to communicate the problem.

Instead of only saying:

"My knee hurts."

you can describe the before and after:

"My knee has hurt after activity for years and usually settles overnight. Over the last few weeks it has started being swollen when I wake up, and the stiffness takes much longer to ease."

That tells the clinician something about pain, but it also tells them about time, pattern and change.

For someone whose medical history already contains a convincing explanation for joint pain, those details can help make a new pattern visible.

Bringing the pieces together

Research often separates complex problems so they can be studied. The person living with them does not have that separation. Hypermobility, inflammation and their effects on the body exist together and may influence one another.

Research is beginning to explore more of these connections. As we understand them better, the hope is that this will also change how we approach care, moving beyond managing each diagnosis separately towards understanding what they mean when they occur in the same person.

After all, the diagnoses may be separate on paper. The person living with them is not.

Next on ParaMotion: Living With Rheumatoid Arthritis: Treatment, Movement, Nutrition and Hypermobility

Next, we’ll look at what we currently know about managing RA, including medical treatment, movement, nutrition and everyday management, and what may need additional consideration when hypermobility is part of the picture. At ParaMotion, we believe that rehabilitation begins with understanding. The body functions as an interconnected system, not a collection of separate parts. By recognising these connections, we can make informed decisions, move with greater confidence, and build treatment plans that support long-term health rather than simply managing symptoms.

👉 [Book your Free 15 mn call here!!] we’ll talk about what’s possible for your body, at your pace.

This article is for education and awareness and does not replace individual medical assessment or diagnosis.