• Usually involve the attachments between your low back and the pelvis (sacroiliac joint).
• Affect areas around the joint where your ligaments and tendons attach to bone (enthesitis), such as at the knee, foot, or hip.

It is important to recognize that the spondyloarthropathies are different from rheumatoid arthritis (RA) in adults and juvenile idiopathic arthritis (JIA) in children.

What causes spondyloarthropathies?

Experts don’t know what causes spondyloarthropathies. The presence of a particular gene, HLA-B27, is often associated with ankylosing spondylitis. Spondyloarthropathies, especially ankylosing spondylitis, are more likely to run in families than other forms of rheumatic disease, such as lupus or rheumatoid arthritis.

What are the symptoms?

Spondyloarthropathies often cause:

• Low back pain that may spread into the buttock.
• Morning stiffness, especially in the back or neck, that gets better during the day and after exercise.
• Fatigue.

Although spondyloarthropathies all result in joint pain, each type also has specific symptoms.

• Ankylosing spondylitis causes stiffness and low back pain. Over time, the pain usually moves from the lower back into the upper back. In severe cases, the affected joints in the spine fuse together, causing severe back stiffness. Other areas (such as the hips, chest wall, and heels) may also be affected. In children, symptoms usually begin in the hips, knees, heels, or big toes and later progress to the spine.
• Reactive arthritis causes pain, swelling, and inflammation of the joints, especially in the sacroiliac joint, the attachment between the lower back and pelvis, and in the fingers, toes, and feet. The fingers and toes may swell, causing a “sausage digit.” Reactive arthritis can also cause fever, weight loss, skin rash, and inflammation. In children, the joints of the lower legs are most commonly affected.
• Psoriatic arthritis is a form of arthritis associated with a skin condition called psoriasis. The psoriasis symptoms (scaly red patches on the skin) often precede the arthritis symptoms, sometimes by many years. The severity of the rash does not mirror the severity of the arthritis. The fingernails and toenails may show pitting or thickening and yellowing. The joint problems involve large joints, such as the hips and sacroiliac joints. Swelling of entire toes or fingers, resulting in sausage digits, also occurs.
• Enteropathic arthritis is spinal arthritis that also involves inflammation of the intestinal wall. Symptoms can come and go. And when the abdominal pain is flaring, this arthritis may also flare. The arthritis typically affects large joints, such as the knees, hips, ankles, and elbows. In children, the arthritis may begin before the intestinal inflammation.
  A general difference between spondyloarthropathies and juvenile spondyloarthropathies is that in adults, the spine generally is affected, while in children the arms and legs are more frequently affected. Children may have 4 or fewer joints that are painful or swollen (typically the knees or ankles), inflammation of a part of the eye (iritis), and neck pain and stiffness.Spondyloarthropathies may cause inflammatory eye disease, particularly uveitis. In some cases, spondyloarthropathies can cause disabilities, particularly if bones in the spine fuse together. People who have spondyloarthropathies for a long time may develop complications in organs, such as the heart and lungs.

How are they treated?

In most cases, spondyloarthropathies are mild and may be undiagnosed for many years. Most people do not have trouble with daily activities. Treatment is focused on relieving pain and stiffness and on good posture and stretching of the affected areas to prevent stiffening and deformity. Nonsteroidal anti-inflammatory drugs (NSAIDs) are commonly used to treat pain and inflammation linked to spondyloarthropathies. Other treatment options depend on the type of spondyloarthropathy you have. For example, medicines are used to treat intestinal inflammation in enteropathic arthritis.