Inflammatory arthritis (IA) is joint inflammation caused by an overactive immune system. It usually affects many joints throughout the body at the same time, but could involve just one joint. Inflammatory forms of arthritis are much less common than osteoarthritis (OA), which is the most common type of arthritis. Although there are many exceptions, inflammatory arthritis generally starts earlier in life, and osteoarthritis later in life.
The major distinction between is the processes that underlie these two diseases, which can have similar symptoms. Osteoarthritis starts in the cartilage, the shock absorber that lines the bone at the joints. Inflammatory arthritis often begins in other soft tissues that line the joint. Osteoarthritis is less of an inflammatory process, although inflammation is still present.
It used to be thought that osteoarthritis was just a “wear-and-tear” process over time, but it is much more complicated than that. Osteoarthritis starts in the articular cartilage, which lines the bone at the joints to allow them to glide smoothly together. This cartilage gets damaged, and the underlying bone becomes thickened and forms spurs (osteophytes). The ligaments of the joint are also involved. Factors that contribute to osteoarthritis are aging, joint injury, genetics, body weight, and other mechanical factors that affect how a person’s joints are aligned.
Inflammatory arthritis is a different process from that in OA. The classic inflammatory arthritis, rheumatoid arthritis, starts in the lining tissue of the joint, the synovium. This lining thickens and cells within it, and within the joint fluid, release chemicals that cause the signs of inflammation – swelling, redness and heat.
In rheumatoid arthritis, multiple joints are often involved at the same time, and often in a symmetrical pattern. This is also true of the inflammatory arthritis seen in lupus. In some kinds of inflammatory arthritis, this joint lining inflammation has a known cause, such as an infection, but in most cases the specific cause is not known.
In gout, an inflammatory arthritis that often attacks just one joint at a time, the cause is known: The body is reacting to an excess of uric acid, leading to deposits of crystals. Pseudogout (a condition with gout-like symptoms but due to very different types of crystals) can involve one joint at a time as well, and it also has a clear cause. Pseudogout results from the body developing an inflammatory reaction to deposits of calcium crystals.
Genetics plays a large part in determining who will get inflammatory arthritis. IA diseases can be diagnosed in patients as young as age 20 or 30. Children and teens may be diagnosed with a form of childhood arthritis, such as juvenile idiopathic arthritis. IA is more common in females than in males, and ongoing studies are searching for all the reasons for this.
The most common symptoms of inflammatory arthritis are:
People with inflammatory arthritis generally experience alternating periods of "flares" of highly intense symptoms with periods of inactivity. Unfortunately, some people have continuous joint inflammation unless treatment is started.
The major types of inflammatory arthritis include:
When detected and treated in its early stages, the effects of inflammatory arthritis can be greatly diminished, or the condition may even disappear completely. The importance of proper diagnosis, particularly in the early stages of the disease, may prevent serious, lifelong arthritic complications.
The Early Arthritis Initiative of the Inflammatory Arthritis Center provides education and support groups for patients with inflammatory arthritis, both early in the course and for those with ongoing joint issues. HSS also offers specialized patient support and education programs for conditions such as lupus and rheumatoid arthritis.
A number of options are available to treat inflammatory arthritis, and the options are different for the different types of IA. Pain and swelling can be treated with anti-inflammatory medications (such as ibuprofen or naproxen), taking into consideration any other medical conditions the person might have. Acetaminophen can be used for pain. Physical therapy and splinting can often be helpful. Sometimes local injections can help a particularly painful joint. In some cases, oral steroids (such as prednisone) are used to “cool down” inflammation.
For people with rheumatoid arthritis, they almost always need a “disease-modifying” medication, which can both hold down their swelling and stiffness and pain, and also help to stop joint damage. For arthritis associated with lupus, multiple medications are available, and picking the right one also involves seeing what other parts of the body are involved. For Lyme disease, antibiotic therapy is needed. For gout and pseudogout, anti-inflammatory agents such as ibuprofen and naproxen and be used, as well as colchicine and short courses of steroids. For gout, we have medications such as allopurinol that can stop the disease by lowering the uric acid level.
With chronic inflammatory arthritis, such as rheumatoid arthritis, it is very often helpful to work with a physical therapist or occupational therapist, to help form a daily strategy for exercise versus rest, and to maintain strength and function.
As with osteoarthritis, joint replacement surgery may need to be considered when these nonsurgical methods have failed to provide lasting benefit. Of the types of inflammatory arthritis, rheumatoid arthritis is one of those most likely to lead to joint replacement. However, fortunately, the number of disease-modifying agents for rheumatoid arthritis has dramatically increased. There is much evidence that the number of people with rheumatoid arthritis needing joint replacement is significantly lower than it used to be, since medications can now stop the joint damage. The progress in treatment of rheumatoid arthritis has been quite dramatic over the decades since the late 1990s.
Learn more about IA from the articles below or find a doctor at HSS who treats inflammatory arthritis.
Explore more in-depth content on the basics of various forms of inflammatory arthritis.
Learn about nonsurgical therapies and surgical options available to treat inflammatory arthritis.
Read about special health considerations for people with inflammatory arthritis, and get tips on how to manage your condition at home and in the workplace.
The below articles are designed to help primary care physicians and other medical professionals diagnose and treat inflammatory arthritis, as well as to determine when to refer patients to a rheumatologist.