Sacroiliitis refers to inflammation of a specific joint in the lower back, called the sacroiliac joint, and usually results in pain felt in the buttock area. Sacroiliac joint problems are frequently misdiagnosed and underestimated. The article talks about sacroiliac joint pain and the role of imaging in establishing the diagnosis and guiding the treatment.
What is the sacroiliac joint?
The sacroiliac joint is located within the lower back, between the sacrum (The lowest part of the spine) and the iliac bone (part of the pelvic bone). We have two of these in our bodies on either side of the lower spine, and they are essential in transferring the forces between the upper and lower body.
What are the causes of sacroiliac joint pain?
There are a few recognised causes of sacroiliac joint pain. These include:
Arthritic changes- This refers to the wear and tear changes that can affect the joints within our body. This is a progressive condition that can be seen in the elderly population.
Previous trauma or injury to the sacroiliac joint
Increased stress upon the joint due to repeated activities like running. There is also increased stress on the sacroiliac joint during pregnancy.
Particular types of inflammatory arthritis associated with autoimmune disorders can cause sacroiliac joint pain and inflammation. This is referred to as “Sacroiliitis “.
What conditions can mimic sacroiliac joint pain?
Sacroiliac joint pain symptoms can be confused with other more common conditions. These include:
Sciatica refers to pain in the buttock and the thigh due to disc herniation within the spine.
Proximal hamstring tendinopathy- refers to inflammation of the hamstring tendons at their attachment to the ischial tuberosity (the sit bone).
Stress fracture- Sacral stress fractures can be seen with increased activity or reduced bone density in the elderly. MRI is very useful in differentiating this from sacroiliac joint problems.
How to diagnose sacroiliitis?
MRI is very useful in confirming the diagnosis when the condition is suspected clinically. It can assess the sacroiliac joint for any inflammation or arthritic changes. It can also assess the adjacent structures to rule out other problems within the lower spine and the hip joint.
An image-guided injection into the sacroiliac joint can also be considered a test. If you experience good results in terms of pain relief, then it will confirm the diagnosis. X-ray is also a perfect modality for the initial assessment of suspected sacroiliac joint problems.
Do I need an X-ray or MRI before a sacroiliac joint injection?
The answer is yes. Imaging is very useful in confirming the diagnosis, assessing the sacroiliac joint, and ruling out other causes of back/buttock pain, as mentioned earlier.
X-ray demonstrating normal sacroiliac joints (arrows)
MRI demonstrating an area of sacroiliitis (arrow)
What is the treatment for sacroiliac joint pain?
Treatment usually starts with physiotherapy, including strengthening and mobility exercises, soft tissue manipulation and massage therapy. Anti-inflammatory tablets can also be useful. A supportive brace can be considered, particularly in pregnant women. If the above measures are not helping with the sacroiliac joint pain, then an image-guided sacroiliac joint injection can be considered.
What type of injections would be useful for sacroiliac joint pain?
Usually, a cortisone (steroid) injection is used. Corticosteroid (cortisone) is a potent anti-inflammatory medicine routinely used to manage inflammatory conditions (like bursitis, arthritis, and tendinosis). The sacroiliac joint is deep, and its anatomy is complex. Image guidance is necessary to ensure safety and accuracy when performing sacroiliac joint injections.
What type of imaging guidance is needed to do sacroiliac joint injections?
Traditionally, X-rays and CT guidance are used when performing sacroiliac injections. The joint is a deep structure with a complex anatomy that can vary among individuals. X-ray and CT provide good visualisation of the bony structures and allow for a safe and accurate procedure.
More recently, practitioners have been using ultrasound to perform sacroiliac joint injections. Ultrasound has some advantages, including lack of radiation and availability. Although some recent studies suggest a similar effect from sacroiliac joint injections when done under ultrasound or X-ray guidance, my experience suggests that it is challenging to perform these accurately using ultrasound guidance. Clinics with practitioners trained to do ultrasound-guided injections only would advertise ultrasound-guided sacroiliac joint injections. However, a radiologist would be the most suitable doctor to perform these as they have experience performing injections using different imaging modalities and often prefer to do these using X-ray or CT guidance.
CT guided sacroiliac joint injection
Hip conditions and treatments