Sacroiliac Joint Pain

The sacroiliac joint (SI joint) is the joint that connects the spine to the pelvis and serves primarily for weight bearing.  When the SI joint is painful, activities such as walking, sitting and standing can stress it, causing worsening pain.  

There are several common causes for SI joint pain:

  • Degenerative arthritis (osteoarthritis) from the bones rubbing against each other when they become damaged or worn away
  • Inflammatory arthritis conditions such as ankylosing spondylitis
  • Pregnancy, which places additional pressure on the bones or causes a change in the person’s gait
  • Any condition that alters the normal walking pattern


Typical symptoms include:

  • Lower back pain, typically below the beltline
  • Pain that radiates into the buttock and posterior thigh
  • Pain may be more commonly experienced on one side of the body but could occur on both sides


To diagnose your condition, we will take a medical history and conduct a medical exam. Based on our findings, we may also use the following diagnostic tools:

  • Imaging such as X-ray, although there are rarely conclusive radiographic findings to correlate with sacroiliac joint pain
  • Diagnostic injection into the joint to identify it as a pain generator


The sacroiliac joint can be a difficult joint to treat because of the various nerve fibers that contribute to its sensation. At the University of Michigan Health System, we have the latest technologies that allow us to provide prolonged pain relief, such as:

  • Medication
  • Physical therapy: Specific physical therapy exercises may correct the underlying biomechanical abnormality that is causing the pain at the SI joint. Patients will typically have home exercises to do to facilitate the improvements in physical therapy. The therapist may employ a variety of manual therapy (‘hands on”) to stretch tight structures and normalize the joint’s mechanics. The therapist may also request that the patient avoid certain activities to prevent recurrent injury.
  • Occupational Therapy: Occupational therapy may be prescribed to provide instruction in activities of daily living including body mechanics and sitting or sleeping postures to prevent recurrence. 
  • Spine injection therapy: This may be considered if pain is too severe to do physical therapy or if the therapy is not effective.
  • Radiofrequency ablation (RFA): RFA of the lateral branches of the sacroiliac joint can treat nerve lesions in a majority of the nerves supplying the posterior part of the joint. This will often offer months of pain relief.

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