back pain physio

What is the sacroiliac joint (SIJ)?


The SIJ is located in the pelvis and connects the iliac bone and the sacrum which is found at the bottom of the spine. It is supported by a strong network of ligaments to provide stability and limits the movements of the pelvis The role of the SIJ is to control and distribute the forces from the upper body to the legs. It acts as a shock absorber to the spine and supports the weight of the upper body


SIJ and back pain


SIJ pain is oftentimes misdiagnosed. It mimics so many other spinal problems and there is no one test that can tell you that you are having a problem with this joint. Patients experiencing low back pain can spend months of even years trying to receive the correct diagnosis.

The SIJ irritation may cause patients experience low back pain. Around 20% of patients with low back pain have problems with the SIJ.  The SIJ is subject to many types of forces: shearing, rotation, torsion, and tension.


What is causing SIJ pain?


Change in gait, trauma, operative fusion in the lumbar spine, laxity of the ligaments, obesity and other inflammatory diseases can also affect the SIJ

The laxity or loosening of the joint decreases around the age of 40 – 50 when the joint can naturally fuse. Pregnant women are very vulnerable to pain as hormonal changes cause joint laxity. Both an increase and decrease in joint laxity leads to pain.

Inflammation of this joint is called sacroiliitis, it gets worse after maintaining the same position for a long period of time

Diseases that can cause sacroiliitis are


  • Psoriatic arthritis
  • Spondylitis
  • Reactive arthritis


Most people with sacroiliitis will present with low back pain, usually worse on one side than the other, pain may radiate to the buttock and upper leg on the affected side. Sacroiliitis is often confused with facet joint pain in the spine,

Although some physical examination and diagnostics with lidocaine injection may suggest the source of the pain, a definite diagnosis can be a challenge.

Chronic SIJ pain defined as persistent pain lasting longer than 3 months may be due to the degeneration or irritation of free nerve endings associated with the SIJ.


Diagnosing SIJ pain


The SIJ problems are difficult to diagnose because of the proximity of this joint to the spine. Patients often think it is the spine that is a problem. It is important to distinguish the pain originating from the SIJ as opposed to the lumbar vertebra. For example, the degenerative disc disease may be interpreted as the SIJ issue when the source of pain is higher in the lumbar spine.

 The key pain pattern for SIJ include the thigh and the knee. Around 50% of patients will experience pain the back of the thighs.


Although there is lack of definite guidelines when it comes to diagnosis the SIJ problems, doctors look for the pain patters in reproduction of the buttock and leg pain pressing on the joint.

MRI is a preferred diagnostic test for evaluation of the SIJ problems.

Conservative treatment of the SIJ include physiotherapy, home exercises, over the counter medication.

Corticosteroid injections or radiofrequency ablation therapy may be offered to patients, but the effectiveness of these treatments remain controversial. In severe cases SIJ fusion may be offered – but again, the effectiveness of this option is unknown.


SIJ pain and how to treat?


Important part of patient recovery is patient education, good posture, lifting techniques, stretching and regular exercise, to strengthen the muscles and ligaments around this joint

Fortunately, sacroiliitis is self-limiting and self-curing process

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