II: Biomechanics Of The Pelvis (PART 1/2)

Question 1

Classification of the SI Joint

Answer 1

• Diarthrodial joint (synovial)
• Upper 1/3 is amphiarthrosis (ligamentous bridge)

Question 2

Much of this kind of pain comes from SI problems:

Answer 2

Low back pain

Question 3

What percentage of chronic low back pain is caused by SI problems?

Answer 3

10-26.6%

Question 4

Major mechanical functions of pelvis:

Answer 4

• Attaches spine to legs.
• Transfers weight to legs.
• Shock absorption.
• Gyroscopic action during gait.
• Females - birth.

Question 5

Pelvis joints:

Answer 5

• 2 SI joints
• Pubic symphysis

Question 6

SI classified as this joint:

Answer 6

Diarthrodial or Synovial

Question 7

Pubic symphysis classified as this kind of joint:

Answer 7

Fibrocartilaginous or Amphiarthrosis

Question 8

Iliac surface has this cartilage:

Answer 8

Fibrocartilage

Question 9

Sacral surface has this kind of cartilages:

Answer 9

Hyaline cartilage

Question 10

What do intrinsic SI ligaments do?

Answer 10

bind sacrum to ilium

Question 11

Muscles related to pelvic biomechanics:

Answer 11

Multifidus, erector spinae, hamstrings, gluteus maximus, piriformis, psoas, quadratus lumborum

Question 12

What innervates the SI joint?

Answer 12

No one knows

Question 13

What is the difference from male pelvis to female SI joint?

Answer 13

Female SI joint has less of an “S” = more mobility. Male SI joint has a more defined “S” shape and decreased mobility.

Question 14

SI joint development at birth:

Answer 14

Joints undeveloped, smooth, flat, glides in any direction. Stability provided by ligaments. Begins to develop during walking.

Question 15

SI joint development during teenage years:

Answer 15

Roughening of surfaces, development of grooves and ridges. Male more pronounced than female.

Question 16

SI joint development during 20s and 30s:

Answer 16

Articulate changes are well established. Joint surfaces become more irregular. Iliac tuberosity gets bigger. Joint surface erosions begin.

Question 17

SI joint development during 40s and 50s:

Answer 17

Each individual SI joint is unique to varying degrees (more in males)

Question 18

SI joint in the 20s and beyond, this possible issue on iliac surface:

Answer 18

Osteoarthritis (DJD)

Question 19

In 40s and 50s, possibililty of developing these issues in your SI joint:

Answer 19

Joint adhesions, osteophytes, fusion

Question 20

60s and beyond, SI joints have a high prevalence of:

Answer 20

Bony ankylosis (fusion)

Question 21

What is bony ankylosis?

Answer 21

Fusion

Question 22

Bony ankylosis is gender dependent (percentages)

Answer 22

Male 27.7% and Female 2.3%

Question 23

Bony ankylosis is age dependent in men (percentages)

Answer 23

• 20-39 years 5.8%
• 60-79 years 31.1%
• Over 80 years 46.7%

Question 24

Fusion occurs mainly in this part of the SI Joint

Answer 24

Superior part

Question 25

Major STATIC function of the pelvis:

Answer 25

Bear trunk weight

Question 26

What is the posterior arch of the pelvis?

Answer 26

2 pillars of bone running through SI and acetabular fossa

Question 27

Which arch is the major weight bearer of the pelvis?

Answer 27

Posterior arch

Question 28

Name the 2 gravitational forces acting on the posterior arch:

Answer 28

1. Down and posterior, weight resisted by wedge-shaped sacrum
2. Down and anterior, weight resisted by “S” shaped joint, posterior ligaments, interosseous ligaments, sacrotuberous ligaments

Question 29

What is the anterior arch of the pelvis?

Answer 29

Pubic rami connects posterior arches and acts as a compression strut

Question 30

Self-locking mechanism of the SI joint is called:

Answer 30

Form closure

Question 31

What is form closure?

Answer 31

• Wedge shape of sacrum
• Interlocking groove (sacrum) and ridge (ilium)
• S-shaped joint surfaces

Question 32

What is force closure?

Answer 32

Tension in muscles, ligaments and thoracolumbar fascia aids in stabilizing the SI joints

Question 33

Force closure in the pelvis:

Answer 33

Creates lateral to medial pressure from ilia to the sacrum which compresses the SI joints

Question 34

Research finds the average ROM for total flexion and extension in the SI is:

Answer 34

1-8˚

Question 35

Describe Sacral Nutation and Counternutation in terms of sacral base movements and lumbosacral extension/flexion

Answer 35

Nutation: Sacral base moves anterior and inferior (lumbosacral extension)

Counternutation: Sacral base moves posterior and superior (lumbosacral flexion)

Question 36

When the lumbosacral region extends, the sacrum:

Answer 36

Nutates

Question 37

When the lumbosacral region flexes, the sacrum

Answer 37

Counternutates

Question 38

During pregnancy there is _________ pelvic joint mobility

Answer 38

Increased (2.5 times)

Question 39

During delivery, the sacrum

Answer 39

Counternutates and nutates

Question 40

When you inhale, your sacrum

Answer 40

Counternutates

Question 41

When you exhale, sacrum

Answer 41

Nutates

Question 42

In flexion, PSIS moves ____ and ___ and in extension, PSIS moves ____ and ___

Answer 42

Flexion: posterior and inferior

Extension: anterior and superior

Question 43

SI joint motion is named according to __________ movement relative to the _________, NO MATTER what bone moves.

Answer 43

Ilium; sacrum

Question 44

Is this flexion or extension of the SI joint: ilium flexes relative to the sacrum

Answer 44

Flexion

Question 45

Is this flexion or extension of the SI joint: the sacrum nutates relative to the ilium

Answer 45

Flexion

Question 46

Is this flexion or extension of the SI joint: ilium extends relative to the sacrum

Answer 46

Extension

Question 47

Is this flexion or extension of the SI joint: the sacrum counternutates relative to the ilium

Answer 47

Extension

Question 48

If PSIS go away from midline:

Answer 48

exteternal rotation

Question 49

If PSIS go toward midline:

Answer 49

internal rotation