Have you ever felt the bony part around your lower back/top of your hips & wondered what the heck that is? It’s your Sacroiliac Joint (SIJ).
Lower-back and buttock pain can have several possible causes, including this joint.
Pain around the lower back or buttock is often blamed on the spine, but the SIJ can also contribute. Understanding this joint can help you choose the right treatment.
What is the SIJ?
You have two sacroiliac joints, one on each side of the hip (pelvis). Each SIJ connects the sacrum—the triangular bone at the base of the spine—to the ilium, the large wing-shaped part of the pelvis.
The front has cartilage-covered surfaces, while the back is reinforced by dense ligaments. Unlike the hip or shoulder, the SIJ is designed mainly for stability and allows only slight movement. Its ridged surfaces help it tolerate substantial forces.
What attaches around the SIJ?
The main stabilisers are the anterior, interosseous and posterior sacroiliac ligaments. Nearby structures, including the iliolumbar, sacrotuberous and sacrospinous ligaments, also support the pelvis.
Muscles and tissues with close connections to the region include the gluteus maximus, piriformis, multifidus, erector spinae, hamstrings and thoracolumbar fascia. Together, they help support the sacroiliac joint during movement.
What does the SIJ do?
The SIJ transfers load between your upper body and legs, helping the pelvis remain stable during walking, running, lifting and climbing stairs. Its slight movement assists with distributing force. Coordinated muscle and ligament tension can also compress and support the joint when needed—a process called “force closure”.
What can trigger SIJ pain?
SIJ-related pain is commonly felt on one side of the lower back or buttock. It may also refer towards the hip, groin or upper thigh. Symptoms can be aggravated by:
- prolonged sitting or standing
- getting out of a chair or car
- climbing stairs or standing on one leg
- rolling in bed
- running, lifting or twisting
- a fall, collision or sudden change in activity
- repeated uneven loading
Pregnancy and the postnatal period can change pelvic loading and ligament behaviour. Previous lumbar fusion, inflammatory arthritis and unequal leg loading may also contribute.
How does a physiotherapist assess SIJ pain?
No single movement or hands-on test can confirm the SIJ as the source of pain. Your physiotherapist will assess your lower back, hips, pelvis, strength & movement. A cluster of pain-provocation tests may be used alongside your history. This is important because hip, lumbar spine and nerve-related conditions can cause similar symptoms.
How can physiotherapy help?
Our physiotherapists will combine education, exercise and hands-on treatment according to the your assessment.
Treatment is tailored to the findings of your assessment and may include:
- education and temporary modification of aggravating activities
- exercises for the gluteal, hip and core muscles
- graded progression of walking, lifting, stairs or sport-specific tasks
- manual therapy for short-term symptom relief
- advice about workplace setup or a pelvic support belt in selected cases
The goal is not simply to “put the pelvis back in place”. It is to reduce irritation, improve your capacity to manage load and help you return confidently to the activities that matter to you.
If pain is severe, follows significant trauma, or is accompanied by fever, unexplained illness, numbness, weakness, or changes to bladder or bowel control, seek prompt medical assessment.
If lower-back or buttock pain is limiting your movement, the physiotherapists at Essential Health Physiotherapy can assess the likely contributors and develop an individual treatment and rehabilitation plan. Contact us to book an appointment at our Shailer Park, Birkdale or Bracken Ridge clinics.
Call us at 07 3132 0898 to be done with your Back Pain.
Clinical sources
Saueressig T, et al. Diagnostic Accuracy of Clusters of Pain Provocation Tests for Detecting Sacroiliac Joint Pain. Journal of Orthopaedic & Sports Physical Therapy. 2021.
Kiapour A, et al. Biomechanics of the Sacroiliac Joint: Anatomy, Function, Biomechanics, Sexual Dimorphism, and Causes of Pain. International Journal of Spine Surgery. 2020.
Vleeming A, et al. The sacroiliac joint: an overview of its anatomy, function and potential clinical implications. Journal of Anatomy. 2012.
Nejati P, et al. Effectiveness of Exercise Therapy and Manipulation on Sacroiliac Joint Dysfunction: A Randomized Controlled Trial. Pain Physician. 2019.
Check our Previous Blogs
- Got Back Pain? It may be the Sacroiliac Joint: What Is the SIJ and How Can Physiotherapy Help?
- Curious about K-Laser Therapy? Here’s How It Works and What to Expect
- Headaches and Neck Pain at Work? Read this!
- 7 Common Reasons for Shoulder Pain at Night (And How Physiotherapy Can Help)
- Hip Pain That Gets Worse When You Sit or Walk: What It Usually Means
