The Sacroiliac Joint (SI Joint) is located in the pelvis; it links the iliac bones (pelvis) to the sacrum (lowest part of the spine above the tailbone). It is an essential component for shock absorption to prevent impact forces during walking from reaching the spine.

What causes Sacroiliac (SI) Joint Pain?

Lower Back Pain SI Joint Pelvis Image

Like any other bone and joint in the body, the large bones of the pelvis and the SI joint can become damaged either through injury or normal wear and tear. The joint can become disrupted or its supporting ligaments may be damaged. Potential causes of SI joint pain include degenerative disease, history of trauma, and other unknown reasons. Symptoms may be immediately obvious (acute) or over time (chronic). When this happens, people can feel problems in their upper leg(s), buttocks and sometimes even higher on the spine. This is especially true with sitting, lifting, running, walking, or even sleeping on the involved side. In all of these cases, the symptoms can be felt anywhere from the lower leg to the lower spine.

The SI joint is a real yet underappreciated pain generator in an estimated 15% to 25% of patients with axial low back pain.1

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Who is most at risk for Sacroiliac (SI) Joint Problems?

There are several groups of patients where sacroiliac (SI) joint problems are more likely:
  • Significant trauma causing a disruption of the SI joint that may result in acute or chronic pain in the SI joint.
  • If the motion in your pelvis is asymmetric, then problems can occur in your sacroiliac joint. You could have asymmetric motion if your legs are significantly different in length, such as from birth or a condition like polio or scoliosis. Having one leg weaker than the other can also cause asymmetric motion and/or instability. Even wearing inappropriate footwear can alter your gait and cause repetitive stress to your sacroiliac joint.
  • Over half the time, SI joint problems are related to a specific event, often an injury from accidents or an event such as pregnancy. In addition to pregnancy, women may be at increased risk for sacroiliac joint problems because of their broader pelvises, the greater curve of their lumbar spines.
  • Other potential causes of SI joint problems include history of trauma, such as occupational lifting.

The SI joint is often missed as a low back pain generator because it is difficult to diagnose. The most significant indication is specific location of pain below the lumbar spine.

In addition:
  • It's common for SI joint problems to feel like spinal disc pain, so SI joint disorders may not get diagnosed if your clinician is not evaluating your SI joint
  • SI joint problems can occur in conjunction with other non-SI joint spinal problems, such as herniated disc, degenerative disc disease, osteoarthritis, or sciatica
  • Patients who are still in pain after lumbar spine surgery may have actually had an SI joint problem instead of or in addition to another spinal problem
  • Patients who have had prior lumbar spine surgery may develop issues with their SI joint. According to scientific data, it's common for pain from the SI joint to feel like disc or lower back pain.2

These diagnostic challenges make it important for patients to bring up the possibility of SI joint problems with their physicians and their other health care providers.

Click here to receive a free information kit (including a doctor discussion guide) and to find a surgeon trained in the iFuse procedure. Request your FREE Kit

1Cohen, Steven P. Sacroiliac Joint Pain: A Comprehensive Review of Anatomy, Diagnosis, and Treatment. Anesth Analg 2005; 101:1440-1453.

2DePalma, Michael J., et al. Etiology of Chronic Low Back Pain in Patients Having Undergone Lumbar Fusion. Pain Medicine 2011; 12: 224–233.

This information is not intended to take the place of a doctor’s advice. The iFuse Implant System® is intended for sacroiliac fusion for conditions including sacroiliac joint dysfunction that is a direct result of sacroiliac joint disruption and degenerative sacroiliitis. This includes conditions whose symptoms began during pregnancy or in the peripartum period and have persisted postpartum for more than 6 months. There are potential risks associated with the iFuse Implant System. It may not be appropriate for all patients and all patients may not benefit. For information about the risks, click here.

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