Do you have nagging low back pain or buttock pain that hasn’t responded to injections, pain medications, or physical therapy? If you haven’t found an answer to your low back pain, it might not be your spine that is the problem. Your unresolved low back pain may be due to sacroiliac (SI) joint dysfunction.
To treat back pain effectively, it’s important to know what’s causing it. Low back pain is a common problem, affecting as many as 85 percent of people at some point in their lives.
What is the SI joint?
The sacroiliac joints are named for the two body parts they connect. They join the sacrum — the triangular bone at the bottom of the spine — to the ilium, or pelvic bone, on either side of the body.
The pelvis looks a bit like a catcher’s mitt, and the SI joints serve a similar role: absorbing shock, bearing weight, and stabilizing the entire body. As the body moves through space and absorbs impact, the SI joints help “catch” and distribute the weight and stress.
What are symptoms of SI joint dysfunction?
In addition to lingering low back pain, dysfunction in the sacroiliac joint can feel like:
- Pain in the buttock — a dull ache on one side of the low back that may affect the hip, thigh, or pelvis. You may avoid sitting or lying on the affected side.
- Pain triggered by daily activities such as walking, running, lifting, or climbing stairs or hills; pain going from sitting to standing.
- Leg pain, numbness, tingling, weakness, or buckling.
What causes SI joint problems?
Arthritis can develop in the SI joint with aging. Repeated stress over time from work, sports, or heavy lifting can also cause SI joint problems.
Other common risk factors for SI joint dysfunction are:
- Injury. The SI joint can be damaged in a fall, car accident, or minor trauma. Typically, this trauma occurs directly to the buttocks.
- Postpartum. The ligaments that support the SI joint stretch during pregnancy to allow for delivery. The joint can remain excessively mobile if the ligaments stay loose postpartum, causing pain and instability. Women who suffer from SI joint dysfunction after pregnancy may experience low back pain and/or pain in their buttocks, hips, groin, and/or legs.
- Previous lumbar fusion. When the lumbar bones of the low back have been surgically fused, it changes the way the spine moves and bears impact. Sometimes this causes stress and pain in the SI joint. People who have had low back fusion often start feeling pain in their low back two years after their surgery.
- Lack of anatomical symmetry. Having scoliosis, one leg longer than the other, or an abnormal gait can create stress and dysfunction in the SI joint, which then causes low back pain and/or pain in the hips, groin, and legs.
How is SI joint dysfunction diagnosed?
It is not always easy to diagnose SI joint problems that cause low back pain and pain in the buttocks. Doctors can misdiagnose SI joint pain as coming from the lumbar spine of the lower back. Sometimes people have coexisting degenerative changes in the spine. But if the pain is arising from the SI joint, spinal injections or surgery that treats the spine but not the SI joint will not relieve the pain.
According to scientific data, it’s common for pain from the SI joint to feel like disc or lower back pain. For this reason, SI joint disorders should always be considered in lower back pain diagnosis.
To pinpoint the cause of your low back pain, your doctor will ask you about your medical history, conduct a physical exam, and consider tests to clarify the source of the pain.
In discussing your medical history, be ready to tell your doctor:
- When the pain started happening? Did it follow a pregnancy, injury, or surgery?
- What makes the pain feel worse? What makes it feel better?
- What activities do you avoid or find difficult?
For the physical exam, your doctor may move your legs and hips into specific positions and apply pressure to see what movements trigger your pain.
Imaging tests such as X-ray, MRI, and CT scans can help in evaluating low back pain. One way to identify pain coming from the SI joint is to inject the joint with a local anesthetic. If symptoms are improved by at least 75 percent but return within hours, the SI joint may be the cause or a major contributor to the low back or buttock pain.
How is pain caused by SI joint dysfunction treated?
The goal of treating SI joint dysfunction is to relieve symptoms and restore stability to the joint. Nonsurgical treatment options include physical therapy, oral medications, SI joint injection therapy, and a pelvic belt that wraps around the hips to stabilize the SI joint.
If conservative treatments aren’t relieving pain after at least six months, your physician may refer you for SI joint fusion surgery, a minimally invasive procedure that requires just three small incisions with no cutting of muscles or ligaments.