5 The SI Joint

Question 1

What are the ligs of the SI jt?

Answer 1

Dorsal:

• posterior sacroiliac: deep to sacrotuberous lig, primary posterior stabilizer of SI jt. Sacrum to ilium.
• sacrospinous: ischial spine to sacrum/coccyx
• sacrotuberous: ischial tuberosity to PSIS, sacrum/coccyx
• interosseous sacroiliac: sacrum to ilium
• iliolumbar: L4-L5 to iliac crest

Ventral:

• anterior sacroiliac: primary anterior stabilizer of SI jt, sacrum to ilium

Question 2

Is nutation or counternutation considered the close-packed position of the sacrum?

Answer 2

Nutation (base of sacrum rotated anteriorly relative to innominate) (hence why sacrum strongly stabilized posteriorly [weight-bearing])

Question 3

In what position(s) would counternutation (loose-packed) be found?

Answer 3

typically in non-weight-bearing, particularly lying in supine

Question 4

How much combined nutation and counternutation is considered normal?

Answer 4

2-4° of rotation

Question 5

What’s form closure?

Answer 5

theoretical, stable situation where closely articulating jt surfaces do not need external forces to bear a given load

Question 6

What’s force closure?

Answer 6

jt compression as result of myofascial and ligamentous tension that provides a lateral force in order to facilitate the jt’s ability to bear a vertical load

Question 7

What are the muscular slings that influence force closure and SI joint stability?

Answer 7

• Posterior longitudinal
• Anterior oblique
• Posterior oblique
• Lateral system

Question 8

What are the components of the posterior longitudinal sling? What action do they have on SI joint?

Answer 8

• sacral multifidi
• erectors
• thoracolumbar fascia
• long head of biceps femoris via sacrotuberous ligament

All increase force closure – with contraction, nutation​/tension on dorsal ligs occurs (hams and erectors tighten sacrotuberous lig while TL fascia and multifidi act directly on sacrum).

Question 9

What are the components of the anterior oblique sling? What action do they have on SI joint?

Answer 9

• internal obliques
• external obliques
• contralateral adductors

Contraction of abdominals and contralateral adductors stabilize spine and pelvis during single leg stance.

Question 10

What are the components of the posterior oblique sling? What action do they have on SI joint?

Answer 10

• latissimus dorsi
• contralateral glute max

All contract as synergists to compress SI joint. Glutes tighten sacrotuberous lig. Lats tighten TL fascia.

Question 11

What are the components of the lateral system sling? What action do they have on SI joint?

Answer 11

• glute med and min
• ipsilateral adductors
• contralateral QL

Ips. adductors and glute med/min work to stabilize pelvis in single leg stance. Contralateral QL works to resist contralateral hip drop.

Question 12

What are S/S of SI joint dysfunction?

Answer 12

• pain over SI joints, inferomedial to PSIS
• pain on palpation of SI joint
• complaining of low back pain
• radiating pain down legs (L4-L5 dermatomal pattern)
• pain while turning over in bed
• pain with load transfer (sit to stand, standing on one leg)

Question 13

What are common compensation patterns for SI joint dysfunction?

Answer 13

• piriformis
• iliopsoas
• adductors
• pelvic floor
• fibrosing of joint

Question 14

How is the stork test performed?

Answer 14

• px transfers load to one leg and brings non-stance hip into flexion at waist height
• we’re looking and feeling for post rotation of non-stance leg innominate/sacral nutation
• in absence of proper pelvic mechanics, we can perform length testing of mm that would prevent post rotation of innominate and sacral nutation

Question 15

How is the forward bend test performed?

Answer 15

• px standing, therapist has hands on iliac crests and thumbs directly under PSIS’s
• px bend forward segmentally wghile keeping knees extended
• therapist observes and feels for movement of PSIS’s – should move equal amount
• positive is if one PSIS moves further than the other

Question 16

How is the femoral shear test aka thigh thrust performed?

Answer 16

• px supine, therapist flexes hip to 90° with knee bent
• therapist sttabilized sacrum with hand and applies vertical pressure to femur
• positive is reproduction of SI joint pain

Question 17

How is the fortin finger test performed?

Answer 17

px points to their area of pain which lies inferomedial to PSIS

Question 18

How is FABER’s test performed?

Answer 18

• px supine, bring hip passively into figure 4 position (flexion, abduction, ext rotation)
• positive is point specific pain at SI joint

Question 19

How is gaenslen’s test performed?

Answer 19

• px supine, maximally flex one hip and drop other leg off table into hip ext
• positive is point specific pain at SI joint of extended hip

Question 20

How is the active straight leg raise test performed?

Answer 20

• px supine, ask them to keep leg straight and flex at hip without cueing for core stability
• if test reproduces pain, perform it again and cue them to engage their core
• if core activation reduces pain, they are a good candidate for tx with stabilization exercises to increase force closure

Question 21

How is the SI joint compression test performed?

Answer 21

• px sidelying, therapist applies downward pressure over iliac crest which causes forward pressure on sacrum, testing SI ligs BL
• positive is point specific pain at SI joint

Question 22

How is the SI joint distraction test performed?

Answer 22

• px supine, therapist crosses hands and places downward and outward pressure on medial aspects of ASIS’s
• test stresses ant SI lig
• positive is pain in SI joint

Question 23

How is the prone straight leg raise test performed?

Answer 23

• two-part test
• px prone and extends hip with leg straight
• if that reproduces SI jt pain, perform test again while placing hands laterally on their iliac crests and compressing in order to stabilize SI jt externally