Sacroiliitis is the inflammation of sacroiliac joints, resulting in lower back pain or buttock pain. The sacroiliac joints are found between the sacral part of the spine (sacrum) and the ilium part of the pelvic bone (hips). It is often overlooked as a source of lower back pain because the presenting symptoms are very similar to other more common diseases. Among cases of lower back pain, only 10 to 25% of them are caused by sacroiliitis. Besides presenting as lower back pain, sacroiliitis also often manifests as one sided buttock pain, and in half of the cases pain is extended down the lower limbs. Sometimes, the pain can be felt around the groin and lower abdomen. Patients may report that the pain worsens after sitting for a long duration or when rotating the body. A number of sacroiliitis treatments are available to control and relieve the symptoms.
What causes sacroiliitis?
Sacroiliitis can be caused by osteoarthritis that results in degeneration of the joint, which leads to abnormal articulation of the joints and pain. Besides, sacroiliitis is a main component in spondyloarthropathies (spine diseases) like ankylosing spondylitis, presenting as pain and stiffness of the spinal joints. Pregnancy may cause sacroiliitis as the hormone relaxin produced during pregnancy leads to relaxation, stretching and widening of the sacroiliac joints. In addition, the increased body weight of the pregnant mother places additional mechanical stress on the joints, causing further wear and tear. Sacroiliitis can also be a result of trauma or injury, directly damaging the sacroiliac joint. Patients who presented with sudden or acute sacroiliitis are mostly due to pyogenic sacroiliitis, a relatively rare form of septic arthritis.
How is sacroiliitis treated?
Generally, sacroiliitis is treated with physical therapy and painkiller medications. Physical therapy is very helpful if the pain is due to overly mobile sacroiliac joints as it helps to stabilise and strengthen the muscles of the back and glutes. Strong muscles can maintain and secure the joints from injury. On the other hand, if the pain is due to immobile or stiff joints, physical therapy helps to loosen tight muscles and increase mobilisation of the sacroiliac joints. An example of the exercises is hip flexion exercise, which is demonstrated as below.
- Lay down flat on your back. Raise the lower legs on a box or pillows.
- Next, cross one foot over the other, squeeze the legs together. Hold and release.
- Repeat this for several times and switch legs.
- Lay down flat on your back. Bent the knees and keep feet flat on the floor.
- Place a pillow between the knees, squeeze and hold for a while, then release.
- Repeat this for several times.
For mild pain, taking over-the-counter analgesics and resting can alleviate the pain. For more severe pain, doctors usually prescribe non-steroidal anti-inflammatory drugs (NSAIDs) and muscle relaxants. For example, naproxen of 375 to 500mg twice daily or celecoxib 100mg twice daily are effective for symptoms of sacroiliitis. Be sure to take naproxen or other non-selective NSAIDs with a proton pump inhibitor (like omeprazole 20mg daily) to mitigate the gastrointestinal side effects of NSAIDs. In cases where sacroiliitis is due to ankylosing spondylitis, TNF-alpha inhibitor (infliximab, adalimumab, etc) is given if pain is not controlled by NSAIDs. As for sacroiliitis caused by other diseases and showing no improvement with NSAIDs, an image-guided intra-articular anesthetic and steroid injections can be performed to achieve pain relief. However, this can only be done periodically to avoid adverse effects from regular use. Additional therapeutic options include electrical stimulation of the joint using a TENS unit (transcutaneous nerve stimulation) and spinal cord stimulation, or radiofrequency ablation. Surgery is typically reserved as a last resort for patients with chronic pain and fails to achieve pain relief from all other methods. In such cases, sacroiliac joint are fused together with screws.