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Sacroiliac Joint Pain (aka Sacroiliitis)

The sacroiliac joint (SIJ) is the largest joint in the body and a common cause of lower back and buttock pain.[1] Fifteen to twenty percent of all lower back pain cases originate in the SIJ.[2] Sacroiliac Joint Pain, also known as sacroiliitis, can present in a variety of ways and is commonly confused with low back pain or a herniated/bulging disc.

Sacroiliitis Low Back Pain, Sacroiliac Joint Pain
Sacroiliac Joint Pain is frequently misdiagnosed as “low back pain”

Sacroiliitis is often overlooked in patients with complaints of low back pain. Treatments that are traditionally very effective for the low back (i.e. Epidurals) are completely ineffective for the sacroiliitis which means the pain will persist.

Sacroiliitis is frequently misdiagnosed as “low back pain” and requires a completey different set of treatments. This can be caused by a number of reasons, ranging from childbirth and arthritis to infection and even colitis.  An accurate diagnosis is important as treatments for sacroiliac joint pain are quite specific to the joint itself.

What is Sacroiliitis?

Sacroiliitis Sacroiliac Joint PainIn simple terms, Sacroiliitis is pain and/or inflammation originating from the sacroiliac joint – the connection between the sacrum (tailbone) and the iliac bone of the pelvis (hip bone).  Sacroiliac joint pain is a common cause of low back pain that can present in a variety of ways:
 Pain radiating from the buttock into the thigh
 Pain in the groin
 Low back pain (lumbar)
 Pain in the posterior thigh and leg
Multiple conditions can affect the sacroiliac joint, including inflammatory, degenerative, traumatic, metabolic, infectious, and cancer. Additionally, there is “sacroiliac joint syndrome,” or pain from the sacroiliac joint without an underlying anatomic lesion, attributed to biochemical abnormalities.[3]

Sacroiliitis is commonly confused with low back pain and requires a totally different type of treatment!

Anatomy of the Sacroiliac Joint

Anatomy of the Pelvic Sacroiliitis Sacroiliac Joint PainThe sacroiliac joint is a highly complex joint and is most often classified as a “diarthrodial” joint. It has several components to its structure:

  • fibrous joint capsule with thick synovial fluid
  • cartilaginous surfaces
  • ligamentous connections.

Unlike most joints, the SIJ is not very mobile – it serves more to provide stability and weight-bearing capability. While there is some small amount of movement in the SIJ, there has not been a relationship seen between the degree of movement of the joint and pain.
The joint is supported by a group of muscles that attach to the joint itself and aid with walking, sitting, standing, and as well as providing support and stability. These muscles include the gluteus maximus and medius, biceps femoris, piriformis, latissimus dorsi and erector spinae.[1] The SIJ is designed for stability and weight-bearing.
The nerve supply to the SIJ is equally as complex and has been the subject of some debate amongst physicians.

  • Dorsal Aspect: innervated by the S1-S3 dorsal rami.[4] Some studies suggest innervation from the L5 nerve, and a recent cadaver study found contribution from the S4 nerve in 59% of joints.[5]
  • Ventral Aspect: innervated by the L4-S2 ventral rami, while others include levels as high as L2.[6][7]

Most physicians will agree that pain from the SIJ can occur from within the joint as well as immediately outside it due to pain receptors being located throughout the joint capsule as well as in the adjacent muscles and ligaments. Pain receptors within the joint capsule are mostly found in the proximal and middle thirds of the joint – this is where most procedures targeting pain from the SIJ will be performed.

What are the Symptoms?

Sacroiliac joint pain can be difficult to tell apart from lower back pain as there is no one-telltale sign distinguishing it from other pain conditions. There are, however, certain signs and symptoms that when seen together seem to point to pain originating from the SIJ rather than other possible causes.
 Pain below the L5 dermatome
 Pain made worse by going from a sitting to a standing position, or with bending
 Pain improved with walking or standing
 Tenderness to palpation over the sacroiliac joint
SIJ pain is more likely to be one-sided rather than typical low back pain that is difficult to localize and may involve both sides or be situated in the midline of the low back. SIJ pain can be referred to various regions of the back, buttock and even the lower extremity making it difficult to tell apart from sciatica or a herniated disc. In most cases, SIJ pain will radiate into:
 Superior medial quadrant or lateral portion of buttock – the most common
 Inferior portion of posterosuperior iliac spine – this can radiate to the greater trochanter, posterior upper lateral thigh or groin
 Pain in the groin
 Pain radiating into the posterior thigh and leg below knee – least common

Learn More About Radiofrequency Ablation to Treat Sacroiliitis

What are the Causes?

There are several factors that can predispose someone to pain from the SIJ, most of which include forces that place an extraordinary amount of stress of the joint (increased axial load or a sudden rotation of the joint, for example).[4] These include disruption of the lining of the joint, ligament injury, muscle pain, shearing forces, cysts, etc.
Reasons for saroiliitis are typically divided into those that affect either the inside of the joint (intra-articular) or the outside of the joint (extra-articular).

Intra-articular sources include:

  1. Arthritis
  2. Spondyloarthropathy
  3. Trauma
  4. Infection
  5. Cystic disease

Extra-articular sources include:

  1. Trauma/fractures
  2. Ligament injury
  3. Myofascial pain
  4. Pregnancy
  5. Cystic disease
  6. Enthesopathy

Extra-articular causes of pain are more likely to result in pain being one-sided. What’s more they occur in younger people, have greater associated tenderness to palpation, and are associated with a trauma or some other inciting event. It becomes important to determine whether the source is intra-articular or extra-articular when determining a treatment plan.

Increased stress from the SIJ can be from:
 Spinal deformities
 Previous spinal surgery
 Leg length discrepancy
 Ligament weakening leading to changes in structural support (i.e. pregnancy).[8]
About 40-50% of people with sacroiliac joint dysfunction report a history of trauma or some inciting event, with the leading causes being motor vehicle accidents, falls, cumulative strain, and pregnancy.[9]

Diagnosing Sacroiliitis

Pain from the SIJ can be difficult to distinguish from pain in the hip, spine or a pinched nerve. Diagnosing sacroiliitis is typically accomplished by a combination of a good history & physical, along with a positive response diagnostic block of the SIJ. This is typically performed under fluoroscopic guidance in the posterior, bottom 1/3 of the joint. A positive response is deemed to be a temporary decrease or even elimination in pain following the block.
Diagnostic imaging (i.e. CT scan, X-ray and MRI) is of little help in diagnosing sacroiliitis unless trauma is suspected.

What are my Treatment Options?

At the Ainsworth Institute of Pain Management, our physicians are uniquely trained in the latest and most advanced treatments for sacroiliac joint pain. Our board certified pain management specialists offer a combination of treatment options for sacroiliitis that that few other centers can.

Learn More About the LinQ Procedure

Interventional Pain Management Treatments

Sacroiliac Joint Block – This injection is considered to be the gold standard in diagnosing SIJ pain and is the first line of treatment.[10]  Typically performed under fluoroscopic guidance, your physician will insert a small needle into the bottom portion of the SIJ and inject a small amount of local anesthetic (sometimes with the addition of cortisone). In the case of true sacroiliitis, pain relief will be immediate and dramatic.
Neurolysis & Ablation – In cases where the block provides only temporary relief, neurolysis or neuroablation can be utilized to increase the duration. There are several different methods that can be used to this end.[11]

  • Radiofrequency Ablation (RFA) – Radio waves are applied to a nerve or plexus, preventing the transmission of pain.
  • Cooled RFA (Coolief™) – This is a highly advanced form of RFA that allows for a higher likelihood of successfully blocking the pain transmitting nerves with less post-procedural discomfort.[12]

***The Ainsworth Institute is one of only a handful of centers in the tristate area capable of performing Cooled RFA

  • Simplicity™ – This is a variation of traditional RFA where a small device called a Simplicity Probe™ is inserted under X-ray guidance along the SIJ. This allows strip lesion of radiofrequency energy to be delivered along the joint.

Sacroiliiac Fusion/Stabilization – In cases where even neurolysis provides only temporary relief, a permanent fusion of the joint may be necessary. Also known as a J-joint arthrodesis, this procedure is used to treat fractures, dislocation, and pain due to degeneration or instability of the joint. This procedure can now be performed in a minimally invasive fashion, with small incisions and the insertion of metal dowels through the pelvis and into the SIJ.

Other Treatment Options

The initial goal in treating SIJ pain is addressing the underlying cause. For example, in the case of a leg length discrepancy causing SIJ pain, a shoe lift and physical therapy should be considered to potentially alleviate the cause and prevent further damage.

Physical Therapy & Conservative Measures  Particular exercises can be useful to stabilize the joint, such as transversus abdominis muscle contractions. There have not been studies done looking at pharmacologic treatment specifically of sacroiliac joint pain. Evidence is therefore drawn from studies looking at nonspecific lower back pain.

Medication Management & Pharmacologic Therapy  In patients who do not have a correctable cause, pharmacotherapy may be used as an adjunct to treatment. Anti-inflammatories, namely NSAIDs, and muscle relaxants may be of some benefit. There is only weak evidence for the benefit of tricyclic antidepressants.[13]

The Ainsworth Institute is Here to Help

The doctors at the Ainsworth Institute of Pain Management specialize in managing and treating sacroiliac joint pain. Dramatic improvements in pain and quality of life are attainable with the right treatment regimen. Schedule an appointment today with one of our board certified pain management experts to discuss what options for treatment may best suit your needs.


[1] Benzon, Honorio. Essentials of Pain Medicine. Philadelphia: Saunders Elsevier, 2011. Print
[2] Schwarzer AC, Aprill CN, Bogduk N. The sacroiliac joint in chronic low back pain. Spine 1995; 20:31-37.
[3] Benzon, Honorio. Practical Management of Pain, 5th Edition. Phildelphia: Saunders Elsevier, 2013. Print
[4] Cohen SP: Sacroiliac joint pain. a comprehensive review of anatomy, diagnosis and treatment Anesth Analg 2005; 101:1440-1453.
[5] McGrath MC, Zhang M: Lateral branches of dorsal sacral nerve plexus and the long posterior sacroiliac ligament. Surg Radiol Anat 2005; 27:327-330.
[6] Nakagawa T: A study on the distribution of the nerve filaments of the iliosacral joint and its adjacent region in the Japanese. J Jpn Orthop Assoc 1966; 40:419-430.
[7] Bernard TN, Cassidy JD: The sacroiliac syndrome. Pathophysiology, diagnosis and management. Frymoyer JW The adult spine. principles and practice 1991 Raven New York 2107-2130
[8] Schwarzer AC, Aprill CN, Bogduk N: The sacroiliac joint in chronic low back pain. Spine 1995; 20:31-37.
[9] Chou LH, Slipman CW, Bhagia SM, et al.: Inciting events initiating injection-proven sacroiliac joint syndrome. Pain Med 2004; 5:26-32.
[10] Maugars Y, Mathis C, Berthelot JM, et al.: Assessment of the efficacy of sacroiliac corticosteroid injections in spondyloarthropathies. a double-blind study Br J Rheumatol. 1996; 35:767-770.
[11] Buijs EJ, Kamphuis ET, Groen GJ: Radiofrequency treatment of sacroiliac joint-related pain aimed at the first three sacral dorsal rami. a minimal approach Pain Clin. 2004; 16:139-146.
[12] Kapural L, Nageeb F, Kapural M, et al.: Cooled radiofrequency system for the treatment of chronic pain from sacroiliitis. the first case-series Pain Pract. 2008; 8:348-354.
[13] Cohen SP, Argoff CE, Carragee EJ: Management of low back pain. BMJ 2008; 337:A2718