What are sacroiliac joints (SIJ) and where are they located?

The sacroiliac joint is large, strong joints between lower end of the spine and the pelvis. There are two sacroiliac joints, one on each side. These joints play an important role in transmitting the upper body weight to the hips and legs and hence undergo a significant amount of stress in day to day life. They function as shock absorbers and are reinforced by multiple strong ligaments. Sacroiliac joints are supplied by a number of nerves which when irritated can hurt.

What causes sacroiliac joint pain?

Sacroiliac joints do not allow much movement as both too much and too little movement can become a source of pain. Some of the causes of SIJ pain include

Trauma/ injuries involving the joints or the surrounding ligaments such as following a fall on the buttock or a road traffic accident.

Mechanical stress due to various reasons such as previous spinal fusion surgery or leg length discrepancy leading to altered weight bearing. As per some studies 75% of patients with previous fusion surgery can develop SIJ degeneration after 5 years.

Inflammation. Sacroiliitis is a term used inflammation of the sacroiliac joint. Ankylosing spondylitis is a type of inflammatory arthritis which can affect the SIJ and the spine. This is seen more commonly in young men. In severe cases it can cause fusion of the sacroiliac and spinal joints leading to pain with reduced range of motion.

Normal wear and tear (degenerative changes.) These are more common with advancing age.

Infections and tumors are fortunately not as common as the other causes of sacroiliac pain.

What are the symptoms of sacroiliac joint pain?

As many as fifteen to twenty percent of all lower back pain cases can be attributed to the issues related to the sacroiliac joint. SIJ pain can mimic pain arising from hip or spine and affects all ages.

Patients with sacroiliac joint pain generally present with buttock or lower back pain and stiffness. Pain is deep aching in character although may be sharp/ stabbing in character. It can involve one or both sides and spread towards the groin, hip, thigh and leg. Activities such as getting up from sitting position, getting in and out of car, climbing stairs, walking and sitting may become painful. Young adults suffering from ankylosing spondylitis generally present with pain and stiffness, worse in the morning and improving with exercises.

How is sacroiliac joint pain diagnosed?

The diagnosis of SIJ pain begins with history and examination of the patient. My usual practise is to perform specific five clinical tests for evaluating the sacroiliac joint and if three or more are positive then the chances of sacroiliac joint involvement is high.

Investigations such as blood tests, X-rays, MRI or CT scans may be requested to confirm the diagnosis. MRI scans reveal greater anatomical details of the joint, but it is important to emphasise that these joints can be the pain generator despite the scans being normal. A diagnostic injection of the sacroiliac joint under X-ray or ultrasound guidance is one of the best ways to confirm whether these joints are the pain source.

How is the sacroiliac joint pain treated?

The treatment can vary depending on the cause of pain. For example, pain resulting from trauma would be treated differently compared to the pain secondary to inflammatory arthritis such as ankylosing spondylitis.

A combination of different forms of therapies (known as the multimodal approach) is used to provide maximum, long-lasting relief. The treatment may include various combinations of the options below

Medications to reduce pain and inflammation.

Physical therapy. This may include posture correction, activity alteration, strengthening of the muscles around the sacroiliac joint and restoring normal joint motion.

Steroid Injections

X-ray or ultrasound guided sacroiliac joint injections are commonly performed to confirm the diagnosis (diagnostic injections) and/or provide pain relief (therapeutic injections). These injections are usually preformed as a day care procedure under local anaesthesia. During the procedure patient is requested to lie on his/her tummy. X-ray or ultrasound guidance is used to steer the needle into or close to the sacroiliac joints. If x-rays are used, a dye is injected to ensure correct needle placement. A mixture of local anaesthetic and steroid is then injected to reduce the inflammation and pain. Ultrasound or X-ray guidance helps to increase the accuracy of injections and reduce the chances of complications.

Prolotherapy and PRP Injections

Prolotherapy uses injection of an irritant solution to create inflammation and induce repair. With regards to the sacroiliac joints this has been used for both ligament and joint problems. These injections differ from the ones described earlier in terms of the medicine injected, injection technique and requirement of multiple injections over time. Ligaments can be visualised with ultrasound and hence ultrasound if preferentially used when dealing with ligament related issues.



Platelet-rich plasma (PRP) used one’s own blood components (platelets) to induce healing response. It works on the principle that increased platelets in an area can enhance body’s natural healing response. PRP is prepared by using one’s blood, spinning it in a machine to separate the platelets and then injecting this into tissues that require healing such as the sacroiliac ligaments. Multiple injections are usually given over the injured area and repeated as needed over a period of time—depending on the severity of injury and the healing response.

Radiofrequency Ablation

This non-surgical day care procedure aims at reducing/blocking the pain signals originating from the painful joints. These signals are transmitted by nerves. Radiofrequency ablation uses heat produced by radio waves to work on these nerves. This treatment has the advantage that it can last longer than the steroid injections described earlier reducing the requirement of repeated injections.

Cooled radiofrequency ablation is a modification of the traditional radiofrequency and uses special needles and other equipment to produce larger treatment areas thereby increasing the chances of successful outcome (pain reduction).

Cooled radiofrequency ablation is a modification of the traditional radiofrequency and uses special needles and other equipment to produce larger treatment areas thereby increasing the chances of successful outcome (pain reduction).

Surgery. This is not required very often. Fusion of the sacroiliac joint may be considered if the above interventions fail to provide adequate relief