Tendons are the tissues that attach your muscles to your bones. Ligaments are what attach your bones to one another. The places where your tendons and ligaments meet your bones are called entheses.
Sometimes, these connection points can get inflamed and become painful because of injury, overuse, or disease. This is known as enthesitis, also sometimes called enthesopathy.
Enthesitis is common in some forms of arthritis, including psoriatic arthritis and ankylosing spondylitis. It also can happen in some children with juvenile idiopathic arthritis (also known as juvenile rheumatoid arthritis).
Common spots for enthesitis to happen are around your heel, knee, hip, toes, fingertips, elbow, backbone, and the bottom of your foot. You'll feel pain and stiffness, especially when you're moving. You also might notice swelling around those areas.
This pain can be different from other types of arthritis pain because you usually feel it next to a joint or spread out over a wider area rather than inside a joint.
Soreness at the back of your heel caused by enthesitis is sometimes called Achilles' tendonitis. This pain can make it hard for you to run or climb stairs.
As the condition gets worse, it can make your tendons and ligaments thick, swollen, or hard, and that makes movement even more painful and difficult. These changes can often be seen with an imaging test such as an ultrasound or MRI.
The Connection With Arthritis
Some kinds of arthritis are autoimmune disorders. This means your body's immune system makes chemicals that attack and damage your own tissues. This can cause enthesitis.
It's a common symptom of two kinds of autoimmune arthritis -- psoriatic arthritis and ankylosing spondylitis. Psoriatic arthritis, which is common in people with the skin condition psoriasis, can affect your entire body. Ankylosing spondylitis mainly affects your spine.
Enthesitis also occurs in about 10% to 20% of children with juvenile idiopathic arthritis, which can affect one or more joints and lasts at least 6 weeks. These children are described as having enthesitis-related arthritis (ERA).
Kids with ERA often have a family history of inflammatory conditions, like ankylosing spondylitis, psoriatic arthritis, or inflammatory bowel disease. They also commonly have eye redness and pain, along with other arthritis symptoms.
Nonsteroidal anti-inflammatory drugs (NSAIDs), like naproxen and ibuprofen, can help with inflammation and pain. If the enthesitis is caused by an autoimmune arthritis, your doctor also may prescribe a disease-modifying anti-rheumatic drug (DMARD), such as methotrexate, or biologics such as adalimumab (Humira), etanercept (Enbrel), or infliximab (Remicade).
He may recommend steroids for areas that are especially stiff or painful.