Sacroiliac Joint Dysfunction Anatomy Quiz

Sacroiliac Joint Dysfunction

• The sacroiliac joint (SIJ) is a pain generator, which refers to abnormal function (e.g. hypo- or hypermobility) at the joint due to altered mechanics.
• It can contribute to lumbar, buttock, hamstring, or groin pain
• SIJ Dysfunction may lead to abnormal joint mechanics, placing stress on surrounding structures.

Anatomy of the Sacrum

• The sacrum forms from the fusion of five sacral vertebrae.
• It creates a triangular or wedge-shaped bone.
• The base of the sacrum articulates with the 5th lumbar vertebra.
• The apex articulates with the coccyx.
• The S1 segment can be mobile, a condition known as lumbarization of S1.
• The fifth lumbar vertebra may fuse with the sacrum or ilium, known as sacralization.
• The lumbosacral angle increases shear stresses at the lumbosacral joint.

Anatomy of the SI Joint

• The SIJ is the articulation between the first three sacral segments and the two ilia of the pelvis.
• The sacrum's auricular surface is concave and covered with hyaline cartilage.
• The ilium is convex and is covered with fibrocartilage.

Development and Function of the SIJ

• The SIJ changes significantly from birth through adulthood.
• It is relatively mobile in young people and becomes stiffer with age.
• The joint surfaces are flat and smooth in children, allowing gliding motion in all directions.
• In post-pubertal individuals, the joint surfaces become irregular forming a tight, interlocking fit (form closure).
• The SIJ connects the spine to the pelvis and absorbs vertical forces.
• It transmits forces from the spine to the pelvis and lower extremities.
• The SIJ is classified as a plane synovial joint with limited motion.

Ligaments of the SIJ

• The SIJ is held together by several strong ligaments: interosseous SI ligament, anterior sacroiliac ligament, posterior sacroiliac ligament, sacrospinous ligament, and sacrotuberous ligament.
• The posterior sacroiliac ligament is stronger than the anterior ligament.

Kinematics of the SIJ

• The SIJ has limited motion, primarily in rotation and translation.
• The SIJ is linked to the symphysis pubis, with any motion in one joint accompanied by motion in the other.
• During pregnancy, the ligaments of the pelvis loosen, increasing range of motion, to facilitate delivery.

Movements of the Sacrum

• Nutation (sacral locking): Forward motion of the sacrum's base into the pelvis (or backward rotation of the ilium on the sacrum).
  • Limited by anterior sacroiliac ligaments, sacrospinous ligament, and sacrotuberous ligament.
  • It is the most stable position of the SIJ.
  • It is an example of form closure.
• Counternutation (sacral unlocking): Backward motion of the sacrum's base out of the pelvis (or forward rotation of the ilium on the sacrum).
  • Limited by posterior sacroiliac ligaments.
  • Occurs in lordotic or anterior pelvic tilt positions.

Kinetics of the SIJ

• The SIJ is vital for supporting body weight.
• Stability relies on form closure (inherent stability from joint shape) and force closure (additional stability from external pressure).
• Body weight creates a nutation torque on the sacrum.
• Ligamentous tension and muscle support contribute to SIJ stability.

Active Stability of the SIJ

• Muscles supporting the SIJ include quadratus lumborum, erector spinae, gluteus maximus, gluteus minimus, piriformis, and iliacus.
• The biceps femoris contributes to SIJ stability through a connection with the sacrotuberous ligament.

Muscle Systems Supporting the SI Joint

• Posterior oblique muscle system (outer group): includes latissimus dorsi, gluteus maximus, and thoracolumbar fascia.
• Anterior oblique muscle system (outer group): includes external and internal obliques, transverse abdominals, contralateral adductors of the thigh, and anterior abdominal fascia.

Precipitating Factors for SI Joint Disorders

• Muscle imbalances:
  • Tight hip flexors (psoas and rectus femoris) and extensors.
  • Imbalances in hip external and internal rotators.
• Leg length discrepancies: Both true (anatomical) and functional discrepancies can contribute to SIJ dysfunction.
• Postpartum changes: Relaxin hormones loosen ligaments, affecting SIJ stability.
• Rheumatoid arthritis or ankylosing spondylitis.
• Psychosocial issues: Anxiety, depression, etc.

Clinical Evaluation of SIJ Dysfunction

• Pain characteristics: deep, dull, undefined, often unilateral, below L5.
• Pain referral: buttock, groin, posterolateral thigh.
• Onset: Acute injury or insidious onset.
• Mechanism of injury: stepping off a curb, fall, prolonged stress.
• Biomechanical abnormalities: excessive subtalar pronation, scoliosis.
• Symptoms: stiffness and pain with prolonged walking, standing, single leg squat, pain with standing from a sitting position, difficulty climbing stairs, pain turning in bed, getting out of bed, or stepping up with the affected leg, tenderness over SI joints and PSIS, pain reproduction over the pubic symphysis.

Physical Examination for SIJ Dysfunction

• Inspection: iliac crest levels, ASIS, PSIS, leg length discrepancies.
• Palpation: SI joint, PSIS, S2 spinous process.
• Functional tests: to assess movement patterns.
• Neurological testing: lower quarter screen.
• Special tests:
  • Mobility tests: Standing, Seated Flexion, Gillet's tests.
  • Pain provocation tests: SI compression and distraction, straight leg raising, FABRE, Gaenslen's, quadrant tests.

Mobility Testing of the SIJ

• Active motion tests:
  • Forward flexion test: tests mobility of the SIJ.
  • Seated flexion test: tests mobility of the sacrum on the ilium.
• Gillet's (Sacral Fixation) Test: tests sacroiliac hypomobility.

Passive Movement Tests

• Hip quadrant test: assesses motion with hip flexion, adduction, and internal rotation.

Other Pain Provocation Tests

• Anterior gapping (distraction) test: tests anterior SI ligament sprain.
• Sacroiliac Joint Stress Test (compression in sideling): tests posterior SI ligament involvement.
• Sacroiliac Joint Stress Test (compression in supine): tests posterior SI ligament involvement.
• Patrick or FABER Test: identifies iliopsoas tightness or SIjoint involvement.
• Gaenslen's Test tests SIJ dysfunction.

Clinical Prediction Rule (CPR)

• Using clinical signs, symptoms, and other findings, CPR estimates the probability of SIJ dysfunction.
• 3 or more positive tests have high sensitivity and specificity for SIJ dysfunction.

Treatment of SIJ Dysfunction

• Conservative treatment:

  • Muscle energy techniques
  • Joint mobilization
  • Joint manipulation
  • Muscle stretching
  • Trunk stabilization (core stability)

• SI belts are generally not recommended.

Soft Tissue Mobilization

• Tight psoas and rectus femoris muscles: common with anterior pelvic tilt.
• Ischemic pressure: applied to hip abductors.
• Sustained longitudinal pressure: applied to the psoas muscle

SIJ Mobilization Techniques

• Aims of mobilization: increase ROM, decrease pain, increase accessory motion, correction of positional faults, examination for SIJ impairment.
• Grades of mobilization:
  • Grade I: small amplitude movement at the beginning range of motion.
  • Grade II: large amplitude movement at the midrange of motion.
  • Grade III: large amplitude movement at the end-range of motion.
  • Grade IV: small amplitude movement at the end-range of motion.

SIJ Mobilization Techniques (Specific Examples)

• Posterior glide of the iliac crest: corrects anterior iliosacral joint rotation fault.
• Anterior glide of the iliac crest: corrects posterior iliosacral joint rotation fault.
• Sacral anterior glide: directs the sacrum into flexion (nutation).
• Sacral posterior glide: directs the sacrum into extension (counternutation).

Correction of Sacral Nutation

• Bilateral anterior nutated sacrum: patient seated with feet apart, flexes forward, pressure on sacral apex with resistance against trunk extension.
• Bilateral posterior nutated sacrum: patient seated with feet together, arms crossed, pressure on sacral base with resistance against trunk flexion.

Test your knowledge on sacroiliac joint dysfunction and its anatomy. This quiz covers the functions and mechanics of the SIJ, as well as the anatomy of the sacrum and SI joint. Understand how these structures contribute to various types of pain and dysfunction.