Causes of Inflammatory Joint Pain

Inflammatory arthritis describes conditions characterized by pain, swelling, tenderness and warmth in the joints, as well as morning stiffness that lasts for more than an hour. The most common forms are rheumatoid arthritis (RA), psoriatic arthritis (PsA), systemic lupus erythematosus (SLE, lupus), gout and ankylosing spondylitis (AS). 

In these diseases, the immune system doesn’t work properly and releases inflammatory chemicals. The resulting inflammation attacks joint tissues and can cause joint swelling, increased joint fluid, cartilage and bone damage, and muscle loss. Nerves in the joints are also activated, causing pain. The inflammatory chemicals may directly activate other nerves of the body and lead to pain as well. 

Inflammatory pain may be caused by: 

• Synovitis. The thin membrane (synovium) lining the joints becomes inflamed, releasing chemicals that irritate nerves and increase fluid in the joint.  

• Bone erosions. Damaged, pitted bones in your joints can cause pain. 

• Swollen joint capsule. Fluid builds in the joint from the inflamed synovium, causing pressure, stiffness and pain. 

• Ligament damage. The effects of inflammation can damage these bands of flexible tissue that support the joint. 

• Muscle weakness. Reduced muscle strength puts more stress on joints. 

• Joint fusion. Especially in AS, small bones that form the backbone (vertebrae) may fuse together, making it harder and more painful to move. 

• Centralized pain. The chronic (long-lasting) pain of inflammatory arthritis can in some cases cause you to become more sensitive to pain. 

Limiting Joint Damage  

Early diagnosis and aggressive treatment that targets the inflammation are the best ways to limit joint damage, pain and other effects of inflammatory, autoimmune types of arthritis.