Final Review

Question 1

Three Joint Complex of the pelvis

Answer 1

Sacroiliac joints

Pubic symphysis

Question 2

Si joints are ____ joints

Answer 2

diarthrotic

True synovial within joint cavity with synovial fluid and joint capsule

Question 3

L shape of SI joint articulates with

Answer 3

Upper half (leg) articulates at the level of S1
Lower half (foot) articulates at the level of S2-3

Question 4

Sacral surface segments (S1-3)

Answer 4

Hyaline cartilage (3X thicker than the ilial surface)
Central groove
Wedge shape superior to inferior
S-shape anterior to posterior

Question 5

Iliac surface from PSIS to PIIS

Answer 5

Fibrocartilage
Central convex ridge
Large rough bony surface posterior and superior to joint for ligamentous attachment (iliac tuberosity)

Question 6

Development changes of pelvis at birth

Answer 6

Joints underdeveloped, smooth and flat, glide in any direction; stability provided by ligaments
Begin to develop during walking

Question 7

Development changes of pelvis in the teens

Answer 7

Roughening of surfaces, development of grooves and ridges (male more pronounced than females)

Track bound movement develops (trail and rail)

Question 8

Development changes in the 3rd through 4th decades

Answer 8

Articular changes in surface anatomy are well established 
Joint surfaces become more irregular 
Enlargement of iliac tuberosities and depression 
Beginning of joint surfaces erosions
Possible osteoarthrosis (DJD) on iliac surface (more in males)

Question 9

Development changes of pelvis at 5th and 6th decades

Answer 9

Joint surfaces become more irregular 
Each individual joint is unique in its topography to varying degrees (more pronounced in males)
Possible osteoarthrosis (DJD) developing on sacral surface and continuing on iliac surface (more in males)
Possible development of joint adhesions, osteophytes, and fusion

Question 10

Changes of pelvis at 70 and above

Answer 10

Interarticular adhesions
high prevelance of bony ankyloses (fusion) 
GENDER DEPENDENT:
Male - 27.7% 
Female - 2.3% 
AGE DEP[ENDENT:
20-39 years - 5.8% 
60-79 years - 31.1%
80+ years - 46.7%

Fusion occurs mainly in the superior part of the joint

Question 11

Intrinsic SI ligaments

Answer 11

Posterior SI ligaments
Interosseous
Dorsal ligaments

Anterior SI ligaments

Joint capsule

Question 12

Posterior SI ligaments

Answer 12

Interosseous: massive, major posterior stabilizer

Dorsal ligaments: smaller, not as critical, from sacrum to the PSIS and iliac tuberosity. Limits anterior movement of the sacral base. Dorsal rami run between interosseous and posterior SI ligaments.

Question 13

Anterior SI ligaments

Answer 13

Thin, thickening of anterior joint capsule

Question 14

Joint capsule of SI ligament

Answer 14

Well developed anteriorly but not posteriorly

Question 15

Extrinsic ligaments of pelvis

Answer 15

Sacrotuberous

Sacrospinous

Question 16

Sacrotuberous ligament

Answer 16

From inferior portion of the sacrum to the ischial tuberosity
Limits posterior movement of the sacral apex

Question 17

Sacrospinous ligament

Answer 17

From inferior lateral portion of the sacrum to the ischial tuberosity
Limits posterior movement of the sacral apex

Question 18

Symphysis pubis

Answer 18

Amphiarthrosis

Interpubic fibrocartilagenous disc

Question 19

Muscles ____ directly act on the SI joint

Answer 19

do not
No muscles cross over the joint

Many MAY influence the mechanical behavior of the joint or respond to stresses applied to it

Question 20

Muscles which may load the SI joint

Answer 20

Erector spinae
QL
Psoas
Iliacus
Piriformis
Gluteals

Question 21

Relationship of muscles to joint dysfunction

Answer 21

Muscles can react to SI stress creating spasms, and trigger points
Abnormal muscle tension may limit overall SI movement leading to joint dysfunction

Question 22

Innervation of SI joint

Answer 22

Neural elements have been identified in the joint capsule and adjoining ligaments suggesting innervation for pain and proprioception but exact innervation is unknown.

Question 23

Keystone effect of the pelvis

Answer 23

Sacrum forms the keystone of an arch suspended by strong sacroiliac ligaments
Inferior displacement (would be bad) resisted by the wedge shape of the sacrum
Posterior displacement resisted by SI ligaments
Anterior displacement resisted by SI ligaments and pubic symphysis

Question 24

Self-locking mechanism of the pelvis

Answer 24

Anatomy of the SI joint promotes stability  (form closure)
wedge shape of the sacrum 
interlocking groove (sacrum) and ridge (ilium)
S-shaped joint surfaces

Tension in muscles, ligaments, and thorcacolumbar fascia aids in stabilizing the SI joint
creates lateral to0 medial pressure fromt eh ilia to the sacrum, compressing the SI joint
clutch like bracing system

Question 25

Dynamic biomechanics of pelvis

Answer 25

Transmit forces between lower extremity and axial skeleton
Shock absorber
Slides and pivots to absorb and adapt to forces generated between trunk and lower extremity during locomotion
Decreases stress to lumbar spine and opposite SI joint

Question 26

SI joint Range of motion

Answer 26

Most agree that it is very small
Egund: up to 2 degrees
Miller: 2.68 degrees flexion, 3.52 degrees extension
Sturesson: 2.5 degrees total motion
Brunner: .54 - 2.83 degrees sacral nutation
Kissling: 1.8-1.9 degrees rotation and translation

Smidt: 5 fresh cadavers in extreme pelvic positions
3-17 degrees, average 7-8 degrees

Question 27

Pelvic movement general statements

Answer 27

Movement decreases with age
Range is greater in females
Predominant plane of motion is around the x-axis in the semi-sagittal plane
Axis of rotation is speculative but most commonly placed posterior to the joint around the iliac tuberosity
Motion is coupled and dependent to some degree on joint separation

Motion is not uniform between individuals
Developmental changes in surface architecture
Movement is greatest during locomotion

Question 28

Illi’s model of locomotion

Answer 28

Reciprocal motion between ilium and sacrum
Flexion of hip and ilium (posterior inferior movement of the PSIS) is accompanied by ipsilateral anterior inferior movement of the sacral base (SI flexion)