Sacroiliac Joint Dysfunction or SI Joint Dysfunction is a condition in which the joint is locked, partially dislocated or “subluxated” in a non-anatomically correct position due to hypermobility (too much movement) or hypomobility (too little movement) within the joint.^[1] Sacroiliac joint dysfunction is commonly characterized by low back and gluteal pain and may be accompanied with referred groin, hip, and sciatic leg pain (see “sciatica“).^[1][2] The condition can affect one sacroiliac joint (left or right), or both joints. The degree of pain and disability due to the condition can vary widely, from an occasional discomfort that limits certain activities to severely debilitating and a constant source of pain.^[1] It is reported to affect between 15% and 38% of the general population, with women being 3 or 4 times more likely to be affected than men.^[3][4][5] In spite of these statistics, many patients with sacroiliac joint dysfunction go years without a correct diagnosis.^[2][6][7][8] The sacroiliac joints are often overlooked as a causative role in lower back pain.^{[2][4][5][6][7][8]}

Anatomy and Physiology of the Sacroiliac Joints

The sacroiliac joint is a true diarthrodial joint that joins the sacrum to the pelvis.^{[1][7][9][10]} The sacrum (tailbone) connects on the right and left sides of the ilia (pelvic bones) to form the sacroiliac joints. The pelvic girdle is made up of two innominate bones (the iliac bones) and the sacrum. The innominate bones join in the front of the pelvis to form the pubic symphysis, and at back of the sacrum to form the sacroiliac (SI) joints. Each innominate bone (ilium) joins the femur (thigh bone) to form the hip joint; thus the sacroiliac joint moves with walking and movement of the torso.^[11]

In this joint, hyaline cartilage on the sacral side moves against fibrocartilage on the iliac side. The sacroiliac joint contains numerous ridges and depressions that function in stability. Studies have documented that motion does occur at the joint; therefore, slightly subluxed and even locked positions can occur.^{[6][7][8][9][12][13][14]}

Muscles and ligaments surround and attach to the SI joint in the front and back, primarily on the ilial or sacral surfaces. These can all be a source of pain and inflammation if the SI joint is dysfunctional.^[6][11] The sacroiliac joint is highly dependent on its strong ligamentous structure for support and stability.^[11] The most commonly disrupted and/or torn ligaments are the iliolumbar ligament and the posterior sacroiliac ligament.^[11] The ligamentous structures offer resistance to shear and loading. The deepanterior, posterior, and interosseous ligaments resist the load of the sacrum relative to the ilium.^[1] More superficial ligaments (e.g., the sacrotuberous ligament) react to dynamic motions (such as straight-leg raising during physical motion).^[1] The long dorsal sacroiliac ligament can become stretched in periods of reduced lumbar lordosis(e.g., during pregnancy).^[1]

Common Symptoms

Common symptoms include lower back pain, buttock pain, sciatic leg pain, groin pain, hip pain (for explanation of leg, groin, and hip pain, see referred pain), urinary frequency, and “transient numbness, prickling, or tingling”.^{[1][2][4][5][6][12][15]} Pain can range from dull aching to sharp and stabbing and increases with physical activity.^[1][6][7] Symptoms also worsen with prolonged or sustained positions (i.e., sitting, standing, lying).^[6][7][11] Bending forward, stair climbing, hill climbing, and rising from a seated position can also provoke pain. Pain is reported to increase during sexual intercourse and menstruation in women.^[6][7][11] Like with other chronic pain conditions, patients with severe and disabling sacroiliac joint dysfunction can suffer from insomnia and depression.^[3]

Affected Muscle Groups

Many large and small muscles have relationships with the ligaments of the sacroiliac joint including the piriformis (see “piriformis syndrome”, a condition often related with sacroiliac joint dysfunction), biceps femoris, gluteus maximus and minimus, erector spinae, latissimus dorsi, thoracolumbar fascia, and iliacus.^[1] Any of these muscles can be involved or spasm with a painful and dysfunctional sacroiliac joint.^{[1][6][7][12][13][14]} The SI joint is a pain-sensitive structure richly innervated by a combination ofunmyelinated free nerve endings and the posterior primary rami of spinal segments L2-S3. The wide possibility of innervation may explain why pain originating from the joint can manifest in so many various ways, with different and unique referral patterns (see “referred pain”) for individual patients.^[1][8] Patients with sacroiliac joint dysfunction can also develop tightness and dysfunction in the hamstring, quadriceps, iliotibial tract (see “iliotibial band syndrome”) and hip flexors, including the psoas muscle. Individuals with severe and long-standing sacroiliac joint dysfunction can develop muscle deconditioning and atrophy throughout the body due to limitation of activities and exercise that bring about pain in the low back.^[1]

Causes of Hypermobility and Hypomobility

Hypermobility

SI joint dysfunction is sometimes referred to as “sacroiliac joint instability” or “sacroiliac joint insufficiency” due to the lack of support the once strong and taut ligaments can no longer sustain.^{[6][7][11][14]} When the joint is hypermobile or loose, it is classified as an extra-articular dysfunction because abnormal joint movement and alignment is a consequence of weakened, injured, or sprained ligaments, while the joint itself is structurally normal and healthy. The sacroiliac joint itself often will not showdegenerative changes, such as arthritis, until many years of the dysfunction being allowed to continue.^[7] Injury to the ligaments that hold the sacroiliac joints in proper support is thought to be caused by a torsion or high impact injury (such as an automobile accident) or a hard fall, resulting in the hypermobility.^[7] As many as 58% of patients diagnosed with sacroiliac joint pain had some inciting traumatic injury based on clinical examination findings.^[15] The joint that was once stabilized by strong ligaments, now overly stretched, sprained, or torn, will move beyond its normal range. This is thought to result in the ilium and sacral surfaces “locking” in an incongruent or asymmetrical fashion (one innominate bone is tilted anteriorly; the other innominate bone is tilted posteriorly) causing pain that can be debilitating.^[7]

Hormone imbalances, particularly those associated with pregnancy and the hormone relaxin, can also cause a ligamentous laxity resulting in the weakening of the sacroiliac structure. ^[16] During pregnancy, relaxin serves as nature’s way of allowing the female pelvis to achieve distention of the birthing canal.^[16] Pelvic joint pain in post pregnancy women is thought to be derived from the inability of the stretched out ligaments to return to normal tautness.^[16] Women who have delivered large babies or who have had extended labors also are prone to developing chronic sacroiliac joint pain and instability.

In some people, the sacroiliac joints reverse the normal concave-convex ‘locking’ relationship, which can lead to rotational misalignment.^[6][7][11] The variation in joint configuration results in some sacroiliac joints being inherently weaker or more prone to misalignment.^[11] Certain biomechanical or muscle length imbalances may ultimately predispose a person to sacroiliac dysfunction and pain. Likely, this is a result of altered gait patterns and repetitive stress to the SI joint and related structures.^[1]These conditions exist in persons with leg-length inequality, scoliosis, a history of polio, poor-quality footwear, and hip osteoarthritis.^[1] There is also a notable incidence of lumbar spinal fusion patients that present with sacroiliac pain and hypermobility, potentially due to the adjacent lumbar joints being fixed and unable to move. Clinical studies have found up to 75% of post-lumbar fusion patients develop SI joint degeneration within five years of surgery.^[17]

Hypomobility

Hypomobility (too little movement) of the sacroiliac joint is an intra-articular disorder in which the joint locks due to wearing down with age or degenerative joint disease. Hypomobility of this kind can also occur with an inflammatory disease such as ankylosing spondylitis,^[18] rheumatoid arthritis, or an infection.

Diagnosis and Testing

Perhaps the biggest reason for misdiagnosis or lack of diagnosis of sacroiliac joint dysfunction is based on the inability of common radiological imaging to discern the disorder. Diagnostic testing, such as X-ray, CT scan, or MRI, do not usually reveal abnormalities; therefore, they cannot reliably be used for diagnosis of sacroiliac joint dysfunction.^[6][11] If the joint has been in dysfunction for many years it may be possible to detect “reactive spurring” or preliminary arthritis due to prolonged abnormal motion within the joint on a computed tomography (CT) scan.^[1]

A clinician well-trained in manual medicine (i.e., a spine surgeon, orthopedic surgeon, sports medicine doctor, physical therapist, physiatrist, osteopath or chiropractor) can diagnose the disorder using a hands on approach by palpating the painful areas as well as administering one or more of the following tests:

• Fortin Finger Test – Palpation may be the most reliable indication of SI joint pain.^[1][7] The clinician will also ask the patient to point directly to the painful area. If the patient points to one particular spot in the dimple of the posterior superior iliac spine (PSIS), the patient can usually precisely reproduce the pain over that one spot. More diffuse back or buttock and leg pain could prompt the clinician to look for a differential diagnosis.^{[1][6][7][11]}
• Gillet Test – Standing flexion testing involves the comparison of the symmetry of motion between the PSIS on the tested side and the S2 spinous process. Inspection often reveals a pelvis with asymmetric height. This finding can be an indication of unilateral restriction in motion of one or both SI joints. While performing this test the clinician should also measure the leg lengths to look for inequality (in patient sitting with legs extended as well as supine) and inspect the lumbar spine to look for scoliosis.^{[1][6][7][8][11]}
• Gaenslen test – This pain provocation test applies torsion to the joint. With one hip flexed onto the abdomen, the other leg is allowed to dangle off the edge of the table. Pressure should then be directed downward on the leg in order to achieve hip extension and stress the sacroiliac joint.^[1][6]
• Iliac Gapping Test – Distraction can be performed to the anterior sacroiliac ligaments by applying pressure to the anterior superior iliac spine.^[1]
• Iliac Compression Test – Apply compression to the joint with the patient lying on his or her side. Pressure is applied downward to the uppermost iliac crest.^[1]
• FABER or Patrick test – To identify if pain may come from the sacroiliac joint during flexion, abduction, and external rotation, the clinician externally rotates the hip while the patient lies supine. Then, downward pressure is applied to the medial knee stressing both the hip and sacroiliac joint.^[1][2][6]
• Thigh Thrust – This test applies anteroposterior shear stress on the SI joint. The patient lies supine with one hip flexed to 90 degrees. The examiner stands on the same side as the flexed leg. The examiner provides either a quick thrust or steadily increasing pressure through the line of the femur. The pelvis is stabilized at the sacrum or at the opposite ASIS with the hand of the examiner

In all tests, pain in the typical area raises suspicion for a sacroiliac joint lesion. Upon neurologic examination, motor strength, sensory examination, and reflexes in the lower extremities should all prove normal. Strength examination can prove challenging to a patient with SI joint dysfunction and they may exhibit weaknesses due to paininhibition or muscle imbalance that has developed during episodes of pain and relative inactivity (deconditioning or atrophy). True neurogenic weakness, numbness, or loss of reflex should alert the clinician to consider nerve root injury or pathology other than a mechanical dysfunction.^[1]

The current gold standard for diagnosis of sacroiliac joint dysfunction is a local anesthetic block performed under fluoroscopy or CT-guidance. The test is administered by injecting an anesthetic, such as Lidocaine hydrochloride, into the painful area of the sacroiliac joint. The diagnosis is confirmed when the patient reports relief from pain. The patient/doctor may decide to administer a corticosteroid at the same time the anesthetic is injected into the painful sacroiliac joint for prolonged pain relief since the numbing agent provides only temporary relief.^[11][19][20]

Misdiagnosis and Controversy within Medical Community

In the early 1900s, dysfunction of the sacroiliac joint was a common diagnosis associated with low back and sciatic nerve pain.^[8] However, research by Danforth and Wilson in 1925 concluded that the sacroiliac joint could not cause sciatic nerve pain because the joint does not have a canal in which the nerves can be entrapped against the joint.^[21] The biomechanical relationship between the sacroiliac joint, the piriformis muscle (see “piriformis syndrome”), and the sciatic nerve had not yet been discovered.^[8]

In 1934, the work of Mixter and Barr shifted all emphasis in research and treatment from the sacroiliac to the herniated intervertebral disc, namely lumbar discs.^[22]Medical focus on herniated discs was further forwarded by the invention of the MRI in 1977.^[23] Recent medical research has revealed that patients with degenerating or herniated discs shown on MRI can frequently complain of little to no pain symptoms, while patients with an unremarkable MRI and no disc pathology can have severe back or sciatic pain.^[24] Over-diagnosis and attention on herniated discs has led to the SI joint becoming an underappreciated pain generator in an estimated 15% to 25% of patients with axial low back pain.^{[1][4][5][7][12][15]}

The ligaments in the sacroiliac are among the strongest in the body^[24] and are not suspected by many clinicians to ever be susceptible to spraining or tearing. Skepticism of the existence of sacroiliac joint dysfunction within the medical community is furthered by the debate on how little or much the sacroiliac joint moves. A discrepancy as large as 2-17 degrees has been reported in clinical findings.^[25][26][27] The normal range of motion within the joint is small often considered being only a few degrees or millimeters,^[1][7][27] hence it is seldom considered as a source of pain in spite of being a load-bearing synovial joint.

Current Treatments

Treatment is often dependent on the duration and severity of the pain and dysfunction. In the acute phase (first 1–2 weeks) for a mild sprain of the sacroiliac, it is typical for the patient to be prescribed rest, ice/heat, physical therapy, and anti-inflammatory medicine.^[1][2] If the pain does not resolve in this time frame, then the patient may benefit from a steroid and anesthetic mixture fluoroscopically injected into the joint (this also serves in confirming diagnosis), as well as manipulative or manual therapy that does not include aggressive spinal adjustments.^{[1][6][7][11][12][14]} For the most severe and chronic forms of sacroiliac dysfunction, treatment should proceed with the support of a sacroiliac belt, a series of prolotherapy injections to aid in regeneration and healing of the surrounding injured ligaments, injection therapy, and finally, surgery.^{[1][6][7][8][11]} The anti-inflammatory effect of injection therapy is not permanent, and the injections do not offer an opportunity to stabilize an incompetent joint.^[28]Surgery is often considered a last resort, but for some patients, it is the only method of effectively stabilizing the loose joint. A fixation of the joint (screws or similar hardware only, without the use of bone grafting) is more common than a spinal fusion, as it is much less invasive, surgically straightforward, and results in a quicker recovery time for the patient.^{[29][7][8][11]} Some experts in the field believe that it is important to make sure the sacroiliac joint is in an anatomically correct position prior to fixation or fusion, but published research contradicts this belief.^{[6][7][8][11][30][31]}

See also

• Sacroiliac joint
• Pelvic floor dysfunction
• Pelvic pain

References

From Wikipedia, the free encyclopedia http://en.wikipedia.org/wiki/Sacroiliac_joint_dysfunction

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