Sacroiliac Joint

Catherine Ricketson and Sarah Wilson

Objective Evaluation of the Sacroiliac Joints

I. Introduction

The sacroiliac joints are part syndesmosis and part synovial joints. The synovial part of the joint is C-shaped with the convex iliac surface of the C facing anteriorly and inferiorly. In children, the SI joint is primarily a synovial joint that is relatively mobile and surrounded by a capsule.[1] As people age, the SI joint transforms from a diarthrodial synovial joint to a modified synarthroidal joint with minimal movement. The articular surface changes from smooth to rough with the adult SI consisting of numerous contoured elevations and depressions within the subchondral bone and articular cartilage.[1],[2] The resting position of the pelvis is in neutral, the open packed position is counternutation, and the closed pack position is nutation. Nutation is defined as a relative anterior tilt of the top of the sacrum compared to the ilium. Counernutation is the reverse motion with a relative posterior tilt of the top of the sacrum relative to the ilium.[1]

The SI joint is primarily reinforced by several strong ligaments [1] :


  • Anterior sacroliliac – thickening of the anterior and inferior regions of the capsule
  • Iliolumbar – stabilizer that blends with the anterior sacroiliac ligament
  • Interosseous – very strong and short fibers that fill the relatively wide gap that exists along the posterior and superior margins of the joint
  • Short sacroiliac – limits all pelvic and sacral movement
  • Long sacroiliac – limits anterior pelvic rotation or sacral counternutation


  • Sacrotuberous – limits nutation and posterior innominate rotation
  • Sacrospinous - limits nutation and posterior innominate rotation

Movement of the SI joint in adults has been reported to be from 1-4 degrees of rotation and 1-2mm for translation; the SIJ is built for stability over mobility.[2] Movement of the SI usually occurs as a combination of compression of the articular cartilage and minimal movement between joint surfaces. Transitional movements such as sit to stand or getting out of a car are typically painful for patients the SIJ dysfunction. The lumbar spine and hip can also refer pain to the SIJ area. SI movement increases during pregnancy due to an increase in ligament laxity occurring during the last trimester. The combination of increased lumbar lordosis, weight gain, and relaxin-induced ligament laxity may stress the SI joints and capsule.[1] The SI joints and the pubic symphysis do not have any muscular attachments that control their movement directly. The SIJ and pubic symphysis are influenced by muscles moving the lumbar spine and pelvis because many of those muscles attach to both the sacrum and the pelvis.[2]


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II. Observation

Gait evaluation [2] – Look for abnormal gait pattern

  • A decreased stride length and vertical limp may be present if the sacroiliac joints are not moving freely
  • Trendelenburg gait may result from reflex inhibition of the gluteus medius due to sacroiliac joint pain

Postural examination [3]

  • Check weight distribution
    • Check to see if patient has equal weight on both feet, more or less on one side compared to the other
  • Check position of the feet
    • The affected limb is usually rotated medially
  • Check for a lateral shift
    • Determine if patient has a lateral pelvic tilt
  • Orientation of the sacrum
    • Check for anterior, posterior, or rotational motion of the base of the sacrum in relation to the ilia
  • Sacrum’s relationship to lumbar lordosis
    • Check for excessive or reduced lumbar lordosis
  • Level of iliac crests
    • Check for symmetry

Check for pelvic tilt or shift:

  • Position of the right ASIS compared to the left ASIS
    • Check for symmetry
  • Position of the right PSIS compared to the left PSIS
    • Check for symmetry
  • Position of the PSIS in relation to the ASIS
    • Compare the ASIS and PSIS on one side to the ASIS and PSIS on the other side
    • The ASIS is slightly inferior than PSIS in normal pelvic alignment
    • If the ASIS and PSIS are both higher on one side compared to the other, this could indicate:
      • an upslip of the ilium on the sacrum on the high side,
      • a shorter contralateral leg, or
      • a muscle spasm from a lumbar pathology [2]
    • If the ASIS is higher on one side of the pelvis and the PSIS is lower on that same side, it could indicate an anterior torsion of the sacrum on that side [2]
  • Level of the pubic symphysis
    • Check the symmetry of the pubic bones
  • Check gluteal and abdominal musculature on both sides
  • Check for symmetry of the gluteal folds
  • Compare the contour of the right buttock to the left buttock
    • The affected side may be flatter if there is loss in tone of the gluteus maximus
  • Check the symmetry of the ischial tuberosities

Clear the joints above and below – see video
• Clear Lumbar spine
• Clear hip

Palpation – Note presence of tenderness, pain, muscle spasm, or other signs that may indicate possible SIJ dysfunction
Supine (Anterior Aspect) [2]

  • Iliac crest
  • ASIS
  • Pubic symphysis
  • Pubic rami
  • Groin

Prone (Posterior Aspect) [2]

  • Iliac crest
  • PSIS
  • Sacroiliac joints
    • Located slightly medial and distal to the PSIS
    • May also palpate in side lying with the patient’s knee flexed to 90 degrees with medial rotation of the hip
  • Sacral Sulcus
    • If one sulci is deeper, it may indicate a sacral torsion or horizontal ilium rotation
  • Ischial tuberosity
  • Soft tissue in buttock, including sciatic nerve
  • Sacrotuberous ligament
  • Sacrospinous ligament
  • Lumbosacral Joint (L5-S1)
  • CPAs S1-5
  • UPAs S1-5

Manual Muscle Testing (MMT)

  • MMT is not needed to assess the sacroiliac joint movement because muscles do not directly control the SIJ

Active Movements
• Flex each knee to chest in standing and lying
• Bilateral isometric contraction of hip abductors and adductors in 90 degrees hip flexion


III. Special Tests

The sensitivity and specificity for three or more of the five positive SIJ tests were 94% and 78% respectively. [4] Three or more out of five tests have the best predictive power and the highest likelihood ratio of 4.29. The thigh thrust and distraction tests have the highest individual sensitivity and specificity, respectively, so the performance of those 2 tests first is reasonable. If both tests are positive for pain, no further testing is required. When all six tests do not provoke the comparable sign, the SIJ can be ruled out as the source of pain. [4]

1. Distraction or gapping [4] – The patient is supine and the PT applies cross-armed pressure to the ASIS directed laterally. This test is assumed to stretch the anterior sacroiliac ligaments.

2. Thigh Thrust [4] – The patient is supine with the knee flexed and the hip flexed to approximately 90 degrees. The PT applies a graded force through the long axis of the femur creating a posterior shearing stress in the SIJ.

3. Compression [4] – The patient is in sidelying with their pain side up and the PT applies pressure into the lateral part of the iliac crest. This test is assumed to stretch the posterior sacroiliac ligaments or compress the anterior part of the SIJ.

4. Sacral Thrust [4] – The patient is prone and the PT applies downward pressure to the sacrum.

5. Gaenslen’s Test [2] – The patient lies supine on the table with the test leg hyperextended at the hip off the table and the opposite hip flexed to approximately 90degrees with the knee relaxed. The PT provides downward pressure on the test leg and a flexion force on the opposite leg.

IIIa. Additional tests for SI involvement

Faber or Patrick’s Test [2] – The patient is supine and the PT places the patients test leg so that the foot is on top of the opposite knee in a figure 4 position. The PT provides downward pressure on the test knee and stabilizes the opposite ASIS. Pain is a positive test.

Supine-to-sit Test [2] – The patient is supine with the legs straight. The PT ensures that the medial malleoli are level. The patient is asked to sit up and if one leg moves proximally farther than the other it could indicate a pelvic dysfunction caused by pelvic torsion or rotation.


True Leg Length Test – The patient is supine with level ASIS and the PT uses a flexible tape measure to obtain the distance from the ASIS to the medial malleolus on the same leg. Both sides are measured and then compared. Nutation of the ilium on the sacrum results in a decrease in leg length as does counternutation on the opposite side.


Neural Tension Tests [2] :

Straight Leg Raise – The patient is supine with legs extended straight on the plinth. The PT passively flexes the hip with the knee extended. Pain occurring after 70degrees is usually indicative of joint pain.
o If pain the SI is unaltered or decreases it could indicated an anterior torsion
o If pain increases in the SI it could indicated a posterior torsion
o If pain increases on the opposite side, it could indicate an anterior torsion on the opposite side


IV. Conclusion

In reality a true incidence of a SIJ pain and disorders is unknown.[3] Confusion surrounds the fact that many portions of the physical examination move many other joints at the same time. The SI joint also possesses a relatively small amount of movements which makes testing and differential diagnosis very difficult and may lead to a wrong conclusion. The inaccessibility of the joint only compounds the difficulty of a manual evaluation of clinicial signs. The majority of patients that are referred to physical therapy for an SI disorder have pain referred from the lumbosacral area.[3] Much more research is required to learn more about the clinical evaluation and management of the SI joint.[1]

V. Bibliography

1. Neumann D, ed. Kinesiology of musculoskeletal system. 2nd ed. St. Louis, Missouri: Mosby; 2010. Accessed October 20th, 2012.
2. Magee D. Pelvis. In: Falk K, ed. Orthopedic physical assessment. Fifth ed. Saint Louis, MO: Saunders Elsevier; 2008:617-658. Accessed October 20, 2012.
3. Banks K, Hengeveld E, eds. Maitland's vertebral manipulation. seventh ed. Saint Louis, MO: Elsevier; 2010. Maitland G., Hengeveld E. and Banks K., eds. . Accessed Oct. 20, 2012.
4. Robinson HS, Brox JI, Robinson R, Bjelland E, Solem S, Telje T. The reliability of selected motion- and pain provocation tests for the sacroiliac joint. Man Ther. 2007;12(1):72-79. doi: 10.1016/j.math.2005.09.004.
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