Examination of the Sacroiliac Joint

About 10-25% of patients with low back pain have SIJ as the primary source of pain. During pregnancy, 20-80% of pregnant women develop low back pain in the region of SIJ. Examination of sacroiliac joint (SIJ) is generally not given due importance. This leads to missed or wrong diagnosis. Examination of SIJ is never done alone and it should be examined as a part of hip examination and lumbar spine examination in those with hip or low back symptoms.

Anatomy

It is the largest axial joint in the body. The size, shape and surface contour shows wide individual variation. SIJ is an auricular or C- shaped joint. It lies between first to third sacral vertebrae. Only the anterior portion is a synovial joint and the posterior portion contains the strongest ligament in the body, the interosseous sacroiliac ligament. The innominate side is covered by fibrocartilage and the sacral side is covered by articular cartilage. Cartilage of the sacral side is thicker than the iliac side. The sacral side has a central depression and the innominate side has a central ridge.

Stability of the sacroiliac joint is provided by the sacroiliac ligaments and accessory ligaments. The sacroiliac ligaments are the anterior and posterior sacroiliac ligaments and the interosseous ligaments. The ligaments are thicker posteriorly than anteriorly. Anterior sacroiliac ligaments are thickenings in the joint capsule. Interosseous ligaments are the most important and have superficial and deep portions which in turn are divided into superior and inferior bands. Posterior ligaments connect the lateral sacral ridge and the posterior iliac spine and iliac crest. The Accessory ligaments include the iliolumbar, sacrotuberous and sacrospinal ligaments.

The structure of the sacroiliac joint evolves with the age of the person. These changes begin after puberty and continue through one’s life time. During adolescence the iliac side becomes rougher and develops areas of fibrous plaques. The changes accelerate after the third and fourth decade with surface irregularities, fibrillation and crevice formation. Sacral side changes begin 10-20 years after the iliac side changes. The joint develops fibrous ankylosis by the sixth decade. Erosions and plaque formation become wide spread by the eighth decade.

The innervation of sacroiliac joint is not yet clearly established. As per various reports, the posterior part of the joint is innervated by branches from the dorsal rami of L3- S3 and the anterior third is innervated by branches from the ventral rami of L2-S2. Innervation from multiple segments leads to referral of pain from sacroiliac joint to different anatomical regions and diverse pain patterns can be observed. But pain from SIJ do not refer to areas above L5.

Biomechanics

The primary function of sacroiliac joint is to provide stability. It transmits the weight of the trunk to the lower limbs. It is weak in torsion and axial compression. Sacroiliac joint provides only small degrees of movement in all 3 axes. In males the movement is predominantly translational and in females it is rotational. Movements are more in females.

Forward rotation of sacrum at the SIJ is called nutation. During nutation the sacral promontory moves anteriorly and inferiorly and the coccyx moves posteriorly and superiorly. This leads to decrease in antero-posterior width of pelvic brim and increase in antero-posterior width of pelvic outlet. The backward rotation of sacrum with opposite effects is called counter-nutation. These movements are probably important during childbirth.

Epidemiology

The prevalence of sacroiliac joint abnormality as the cause of pain in patients with low back pain is often missed. It is reported to be the primary source of pain in 10-25% of those patients with low back pain. Around 20-80% of pregnant women complain of posterior pelvic pain or low back pain felt in the region of sacroiliac joint. Pain during pregnancy usually begins during the 18-24 week period and usually subsides by the end of 2 months after delivery. However 5% may complain of persistent symptoms at the end of 3 years after delivery.

History

Pain in the sacroiliac region may be either due to localized causes or referred causes. Pain over the SIJ may be referred from intervertebral disc or facet joint lesions. In addition, pain of sacroiliac joint lesions may radiate to the buttock, lower lumbar region or buttock. Hence it is often difficult in many patients to identify the exact source of pain.

Cause of pain may be intra-articular or extra-articular. Intra-articular causes may be arthritis, infection or trauma. Extra-articular causes may be enthesopathy, fractures, ligamentous injury or lesions of adjacent ilium, sacrum or soft tissue structures. Causes may be classified as inflammatory disease, infection, tumor, metabolic disorders, degenerative disease, iatrogenic conditions, referred pain, and trauma.

Limb length discrepancy, abnormal gait, prolonged exercise or scoliosis may lead to mechanical derangement of sacroiliac joint leading to pain. Pregnancy is a well-known risk factor for sacroiliac pain due to weight gain, excessive lumbar lordosis, injury during delivery and hormone induced ligamentous laxity.

Symmetrical or asymmetrical sacroiliitis is a common finding in spondylarthropathies.   Ankylosing spondylitis commonly causes symmetrical involvement and other spondylarthropathies lead to asymmetrical involvement.

Examination

Many of the problems of sacroiliac joint are missed and often attributed to hip or spine disease as the history and clinical tests are often nonspecific. Careful physical examination is needed for proper diagnosis.  Point specific tenderness at the sacral sulcus or posterior superior iliac spine is a consistent finding in sacroiliac joint lesions. Tests for sacroiliac joint can be divided into motion palpation tests and pain provocation tests. Gillet test is the most commonly done motion palpation test.

Gillet test

Patient position- Standing.

Examiner position- Standing behind the patient, with one thumb over the S2 spinous process and the other thumb over the posterior superior iliac spine (PSIS) of the tested side.

Procedure- Ask the patient to maximally flex the hip on the tested side.

Interpretation- Normally PSIS moves inferiorly in relation to the S2 spinous process. If it remains at the same level then there is SIJ dysfunction.

The provocative tests done for sacroiliac joint do not test the sacroiliac joint alone; hence lesions in the adjacent structures also will elicit a positive test. This is the main reason for lack of specificity for these tests.

Sacroiliac distraction test

Patient position- Supine on a couch.

Examiner position- Standing with each hand placed over the anterior superior iliac spine on either side.

Procedure- Apply posterior directed force to distract the sacroiliac joint.

Interpretation- Pain at the sacroiliac region is suggestive of sacroiliac pathology.

Thigh thrust test

Patient position- Supine on a couch with the hip and the knee flexed to 900 and the hip slightly adducted.

Examiner position- Standing with one hand placed over the sacrum and the other upper limb wrapped around the knee.

Procedure- Apply posterior directed force to on the vertically oriented femur to apply a shearing force on the sacroiliac joint.

Interpretation- Pain at the sacroiliac region is suggestive of sacroiliac pathology.

Gaenslen’s test

Patient position- Supine with one limb hanging over the edge of the couch.

Examiner position- Standing.

Procedure- Maximally flex one lower limb on to the abdomen and maximally extend the other hip hanging beyond the edge of the couch.

Interpretation- Pain at the sacroiliac region is suggestive of sacroiliac pathology.

Sacroiliac compression test

Patient position- Lateral position with hip and the knee bend to 900.

Examiner position- Standing with both hands placed on the iliac crest.

Procedure- Apply firm pressure on the iliac crest.

Interpretation- Pain at the sacroiliac region is suggestive of sacroiliac pathology.

Patrick test or FABERE (Flexion-Abduction-External rotation- Extension) test or Figure 4 test

Patient position- Supine

Examiner position- Standing.

Procedure- Ask the patient to keep the hip in flexion-abduction-external rotation position, knee in 900 flexion with the foot resting on the opposite limb. Apply pressure on the knee to force the hip into extension.

Interpretation- Pain felt in the region of SIJ is suggestive of SIJ lesions.

REAB (Resisted abduction) test

Patient position- Supine.

Examiner position- Standing holding the patients leg at the ankle.

Procedure- Ask the patient to abduct against resistance.

Interpretation- Pain felt in the region of SIJ is suggestive.

Sacral thrust test

Patient position- Prone position.

Examiner position- Standing with both hands placed on the sacrum.

Procedure- Apply firm pressure on the sacrum.

Interpretation- Pain at the sacroiliac region is suggestive of sacroiliac pathology.

Yeoman test

Patient position- Prone position.

Examiner position- Standing and holding the patient’s tested lower limb at the knee.

Procedure- Hyperextend the hip.

Interpretation- Pain at the sacroiliac region is suggestive of sacroiliac pathology.

Thigh thrust test is most sensitive and distraction test is most specific. Only thigh thrust test reaches more than 80% sensitivity and specificity. In the absence of centralization, if three provocative tests are positive then the sensitivity, specificity and positive likelihood ratio are 93%, 89% and 6.97%, respectively. Hence practically it is sufficient to do the thigh thrust test, sacroiliac distraction test and the FABERE test to arrive at a diagnosis.

Further Reading

Laslett M, Young SB, Aprill CN, McDonald B. Diagnosing painful sacroiliac joints: a validity study of a McKenzie evaluation and sacroiliac joint provocation tests. Australian Journal of Physiotherapy 2003;49:89–97.

Mark Lasletta, Charles N. Aprill, Barry McDonald, Sharon B. Young. Diagnosis of Sacroiliac Joint Pain: Validity of individual provocation tests and composites of tests. Manual Therapy 10 (2005) 207–218.