Sacroiliitis: The sacroiliac joints (SI joints) connect the spine to the pelvis and lower skeleton. These joints provide minimal movement; approximately two to four millimeters with weight bearing activity, unlike that of the hip or knee. The SI joint's main function is to provide shock absorption for the spine through a gliding-type motion. Sacroiliitis (inflammation of the SI joint) is commonly caused by degenerative arthritis, traumatic injury, motor vehicle accident, or blow to the buttock or pelvic region. Women are at risk for developing sacroiliitis from childbirth, as the female pelvis must stretch enough to allow birth. The ligaments around the joint, which connect one bone to another, may become inflamed or torn. Tearing of these ligaments can lead to too much motion in the joint, causing degenerative changes and chronic pain.

Symptoms: In most cases of sacroiliitis, there is a diffuse pattern of back and pelvic pain that mimic each other. Patients with SI inflammation will generally complain of low back, buttock, and thigh pain. This pain typically becomes worse when sitting for any prolonged period of time.

   Sacroiliitis is commonly confused with sciatica. Many rheumatic diseases aren't limited to inflammation of the joints and extend to other organs of your body, such as your skin, blood vessels, eyes, heart, lungs, kidneys and nervous system.

Signs and symptoms of sacroiliitis may include: Pain and stiffness in your lower back, thighs or buttocks, especially in the morning or when sitting for a long period of time. Pain affecting your hips and shoulders. Pain that worsens with walking because the swinging motion of your hips strains your sacroiliac joints. Inflammation in one or both of your eyes (uveitis or iritis). Psoriasis, an inflammatory skin condition. Bloody diarrhea. A low-grade fever that appears quickly.

Causes: A wide range of factors may cause sacroiliitis:

Heavy lifting, especially if you lift incorrectly or your muscles aren't prepared for the activity.

A traumatic injury or sudden impact, such as a motor vehicle accident or a fall, affecting your spine, lower back, pelvis or buttocks.

Spondyloarthropathies, which include ankylosing spondylitis, arthritis associated with psoriasis and others.

Degenerative arthritis, also called osteoarthritis of the spine, causing degeneration of the sacroiliac joints, which can cause mild inflammation and pain.

Pregnancy, because the pelvis must stretch to accommodate childbirth. Infection of the sacroiliac joint, sometimes caused by bacteria in food (brucellosis).

Treatment: In most cases rest, anti-inflammatory medication, and physical therapy alleviate symptomology. Physical therapy should focus on mobilization (exercise and manipulation by the therapist), and stabilization (muscle strengthening).

For pain relief, fluoroscopic guided injections into the joint may be warranted. The SI joint is located deep in the buttock region and is covered by thick muscle. The fluoroscope uses X-rays to help visualize the SI joint. This visualization allows the physician to see on screen the exact placement of the needle into the joint. Cortisone is typically injected into the joint to calm the inflammation and reduce pain.