SI Joint Interventions

Question 1

Primary Function - SI

Answer 1

• Load transfer from axial to lower quarter

Question 2

The stability of the pelvic system comes from…

Answer 2

• anatomic shape + gravity
• ligamentous support
• muscular stabilizers

Question 3

How does axial loading lead to motion in the pelvis?

Answer 3

• As the spine is loaded results in a downwards for on the sacrum.
• This results in a wedging effect of compression from the sacrum and iliac bones
• In addition, causes sacral flexion, tightening of the ligaments.
• Due to inertia, force also leads to compression of the pubic symphysis

Question 4

What does nutation/couternutation mean?

Answer 4

• nutation = sacral flexion
• counter nutation = sacral extension

Question 5

What ligaments resist sacral flexion?

Answer 5

• Sacrotuberous and Sacrospinous

Question 6

Where is the axis of rotation for the sacrum?

Answer 6

S1-S2

Question 7

What resists sacral extension?

Answer 7

• Posterior Sacroiliac ligaments

Question 8

____ - there are a large numebr of muscles with direct or indirect influences

Answer 8

• Dynamic Stabilizers
• Psoas, iliacus, Quadratus lumborum, Erectors, multifidi, abdominals (all layers), latissimus dorsi, gluteus maximus/medius/minimus, hamstrings (esp. biceps femoris), piriformis, tensor fascia lata, rectus femoris, levator ani, adductors, hip rotators

Question 9

What is important about the muscles surrounding the pelvis?

Answer 9

• They work in muscle synergies to balance spine and pelvis
• If one muscle is not working properly results in compensation (one muscle not work, other overworked)

Question 10

Pelvis: Gluteus Maximus and Lattisumus Dorsi

Answer 10

• Fiber diagonal connections may lead to functional compression to support SI region

Question 11

Due to muscle function being a major component of pelvic function, we need to…

Answer 11

• assess muscle function!!!

Question 12

The pelvic ring must move for successful ____

Answer 12

transfer of force

Question 13

What motions of the ilium and sacrum are well supported?

Answer 13

• Ilial rotation (Anterior/Posterior)
• Sacral Flexion/Extension

Question 14

How much does the ilium move?

Answer 14

• 2-3 degrees Ant/Post
• 3 degrees internal rotation (inflare)/external rotation (outflare)

Question 15

If the sacrum goes into flexion, what does this mean? What happens at the lumbar spine?

Answer 15

• Sacral Flexion: Superior aspect moves anterior, inferior aspect moves posterior (Opposite for counternutation)
• Lumbar goes into extension (opposite for counternutation)

Question 16

What is an oblique axes of rotation for the Sacrum?

Answer 16

• Oblique: Superior aspect on one side to the inferior aspect on the other side (Combo Rotation/SB - Torsion)
• Press on the left leads to anterior movement and posterior movement on the lower right
• Press on the right leads to anterior on upper right, posterior on lower left

Question 17

Pubic Symphysis

Answer 17

• Synovial Joint
• Torsional movement; Superior-inferior motion
• Important for functional activities like walking; right needs to be different than left
• Often times treating the SI joint results in pubic symphysis being treated as a byproduct