The sacroiliac (SI) joints lie next to the spine and connect the sacrum, a triangular bone at the base of the lumbar spine and tailbone, with the hip on both sides. These joints absorb shock and pressure and allow for forward and backward bending. There are two sacroiliac joints, for each hip joint. Joint inflammation and/or dysfunction in this area can cause pain.
The purpose of a sacroiliac joint injection is two-fold: to diagnose the source of a patient’s pain, and to provide therapeutic pain relief. At times, these are separated, and a patient will undergo a purely diagnostic or therapeutic injection, although often the two are combined into one injection.
A diagnostic SI joint injection is used to confirm a suspected diagnosis of sacroiliac joint dysfunction.
- Pain Relief
A therapeutic SI joint injection is done to provide pain relief associated with sacroiliac joint dysfunction. The injection is performed using the same technique as a diagnostic SI joint injection, except that additional medications may be used. These procedures can be repeated approximately three times a year and helpful so that the person can continue physical therapy and rehabilitation.
What Causes Sacroiliac Joint Pain?
- Gait issues, such as leg length discrepancy or scoliosis (curvature of the spine), which can place uneven pressure on one side of the pelvis, causing wear-and-tear on the SI joint and an increased risk of pain.
- Pregnancy or recent childbirth can cause sacroiliac joint pain in women due to weight gain, hormonal changes that cause relaxation of the ligaments in the SI joint, and pelvic changes associated with childbirth. For some women, ligaments may remain loose after childbirth and cause sacroiliac joint pain and instability to continue.
- Prior lower back surgery, One study found that sacroiliac joint pain was more common following a fusion surgery than with a discectomy. The same study found that multi-level surgery was more likely to cause sacroiliac joint pain than a single-level procedure. Sacroiliac joint pain can occur after hip joint replacement surgery and when bone grafts taken from the iliac bone (the “wings” of the pelvis).
- Activities that place repeated stress on the joint, such as contact sports, regular heavy lifting, trauma, or labor-intensive jobs. If pelvic and/or low back muscles are weak and unconditioned, stress from prolonged sitting or standing may also contribute to SI joint pain.