About the Sacroiliac (SI) Joint
The sacroiliac joints are strong joints (or articulations) between the bottom-most triangular bone of your spine, called the sacrum, and the ilium sections of the pelvis (the sections of the pelvis you put your hands on when you “put your hands on your hips”).
The Function of the Sacroiliac Joint
The function of the sacroiliac joint is both shock absorption (depending on the joint’s possible amount of movement) and torque conversion, to transfer movement in your lower body up to your spine.
Sacroiliac (SI) Joint Dysfunction
Your sacroiliac joints act a lot like the suspension system in a car—they absorb your body’s daily dose of steps, jolts, and bumps, and they provide you with stability. However, inflammation, normal wear and tear, or even a single incident or accident can damage your SI joint, affecting their slight normal movement and creating chronic and often debilitating low back pain.
Common Causes of Sacroiliac (SI) Joint Problems
- Injuries (a fall, car accident, or even a simple misstep)
- Pregnancy (the ligaments that allow the SI joint to stretch to allow for delivery may remain loose, post-pregnancy)
- Anatomic variation (such as uneven leg length or scoliosis)
- Prior lumbar surgery (fusion of the lumbar spine changes its natural movement and ability to absorb shock)
- Inflammatory joint disease (sacroiliitis)
The Difference Between Sacroiliac Joint Dysfunction and Inflammation
- Sacroiliac joint dysfunction refers to pain in the sacroiliac joint region due to abnormal movement in the sacroiliac joint—either too much movement or too little. This abnormal joint movement typically results in inflammation of the sacroiliac joint.
- Sacroiliac joint inflammation, called sacroiliitis, describes inflammation in the sacroiliac joint. Sacroiliac joint inflammation may or may not be caused by sacroiliac joint dysfunction.
Why Sacroiliac Joint Dysfunction or Inflammation May Cause Pain
When the strong ligaments of the sacroiliac joint become damaged, they may move excessively or insufficiently, causing inflammation and disrupting the joint and its surrounding nerves. When this happens, you may feel pain in your low back, buttocks and/or legs, especially while walking, running, lifting or even sitting or lying down.
Common Symptoms of Sacroiliac Joint Dysfunction or Inflammation
- Pain in your low back, buttocks, and/or legs
- Pain or discomfort performing common daily activities that require your pelvis to pivot, like getting in and out of bed, walking up or down stairs, or even turning in a chair
- Difficulty sitting or lying down, especially if you experience an ache on one side of your body so painful it requires shifting your weight to the other side to gain relief
Diagnosing Sacroiliac Joint Dysfunction or Inflammation
The consulting doctor will ask about symptoms, medical history, and level of physical activity, and may conduct additional tests depending on the information provided. These diagnostic tests may include provocative maneuvers designed to gauge the scope and degree of sacroiliac joint pain. Your doctor may also take X-rays of the pelvis and low back, a CT scan, or an MRI scan. Additionally, the doctor may also conduct tests based on joint injections or nerve blocks: drugs that temporarily block nerve signals from parts of the affected area to determine if pain originates in the SI joint.
Sacroiliac Joint Dysfunction and/or Inflammation Diagnosing Challenges
Many of the symptoms of sacroiliac joint dysfunction and/or inflammation mimic symptoms of low back pain, such as pain in your low back and legs, so it may not initially be correctly diagnosed. A trained and experienced physician is your best resource for correctly identifying the root cause(s) of low back pain and discomfort.
It has been reported that up to 30% of all chronic low back pain is due to SI joint dysfunction.1,2 However, patients with SI joint dysfunction may not be correctly diagnosed, leading to unnecessary treatment such as lumbar spine surgery. Additionally, the sacroiliac joint is the most likely source of low back pain after lumbar fusion.3
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1 Simopoulos TT et al. (2012) A systematic Evaluation of Prevalence and Diagnostic Accuracy of Sacroiliac Joint Interventions. Pain Physician; 15:E305-E344
2 Cohen SP et al. (2013) Sacroiliac Joint Pain: A Comprehensive Review of Epidemiology, Diagnosis and Treatment. Expert Rev Neurother; 13(1):99-116
3 DePalma MJ et al. (2011) Etiology of Chronic Low Back Pain in Patients Having Undergone Lumbar Fusion. Pain Medicine; 12:732-739