February 28, 2021
The sacroiliac joints (SIJ) are located at the back of the pelvis between the base of the spine (sacrum) and the hip bones (the ilium). The joint surfaces are covered with articular cartilage and the joints are reinforced by thick, strong ligaments, that normally give the joint great stability.
The SIJ helps to transmit forces during weight bearing activities, but only moves by a couple of millimetres.
However, the SIJ can produce pain, due to mechanical factors such as:
The 'self braced' position of the SI joint can be altered by these factors and the joint can lose its stability. This changes the mechanics of the joint, putting abnormal pressures on the joint surfaces, ligaments and surrounding muscles. It is easy to see how trauma can produce this problem; when a person lands on one buttock during a fall, for example. A similar process may occur gradually if there is altered alignment or a discrepancy of length in the legs. This can lead to SI joint dysfunction and pain due to repeated stresses on the SI joint during sporting activities.
Hormonal changes during pregnancy can cause generalised laxity of ligaments that can cause mechanical SI joint dysfunction. The ligaments helping to stabilise the SI joint can become lax and this, together with increased load on the spine due to the pregnancy, can cause altered SIJ mechanics and pain. For this reason, mechanical SIJ dysfunction tends to be more common in women.
Mechanical SIJ dysfunction typically causes a dull ache that is located at the base of the spine on the affected side(s). The pain may become worse and 'sharp' in nature during activities such as sitting, bending, lifting, standing up from a seated position, or lifting the knee up to the chest during stair climbing. Sometimes the pain can refer to the groin, buttock or the back of the thigh although SIJ pain rarely goes below the knee.
A thorough physiotherapy assessment by a physio skilled in SIJ treatment will determine if SIJ dysfunction is causing your symptoms, as these symptoms can be similar to lower back pain.
Analgesic medication for pain relief, and possibly anti-inflammatory
If your GP suspects a genetic, inflammatory joint disease, they may choose to do blood tests, and refer you to a rheumatologist, however, these are relatively rare conditions.
Treatment of mechanical SIJ dysfunction usually responds well to conservative treatment from a Physiotherapist. In the case of a woman who is suffering from SI joint dysfunction during pregnancy, it may not be possible to eradicate the problem until after the birth. Then, once ligamentous laxity is no longer such an issue, steps can be taken to restore normal SI joint mechanics.