SI joint

Question 1

describe the 3 sacral surfaces related to the SI joint

Answer 1

ala
auricular surface
rough surface - posterior

Question 2

describe the two ileum surfaces of SI joint

Answer 2

auricular
post-auricular - iliac tuberosity

Question 3

describe the SI joint

Answer 3

synovial plane
surrounding joint capsule
syndesmotic part - between iliac tuberosity and posterior depressions

Question 4

describe the ligaments of the SI joint

Answer 4

anterior SI - thickening of joint capsule
Posterior SI - over interosseous ligament
ilio-lumbar
sacrotuberous
sacrospinous

Question 5

describe the SI joint neurovasculature

Answer 5

arterial via iliolumbar, lateral sacral and superior gluteal
venous - same pattern
nerves from L5-S3 post rami

Question 6

describe the development of the SI joint

Answer 6

evidence by 7-8 weeks iu
3 layers - sacral and iliac cartilage with interposed mesenchyme (forms synovial membrane)
by 10 weeks - joint cavities form
fibrous septa extend into cavities
complete cavities by 7-8 months

Question 7

describe the changes to the SI joint during life

Answer 7

straight and parallel to VC at birth
curves over time due to growth, posture and movement
surfaces become ridged

Question 8

describe sexual dimorphism of the SI joint

Answer 8

male joint surface greater
female joint more prone to misalignment
paraglenoid sulcus creates bony ridge at anterior joint capsule in women only

Question 9

what are the primary and secondary functions of the SI joint

Answer 9

primary - load distribution and facilitating childbirth
secondary - protection of pelvic contents

Question 10

describe the effects of nutation

Answer 10

pelvic outlet diameter increases, pelvic inlet diameter decreases

Question 11

what impacts force dispersion at the SI joint

Answer 11

muscles, ligaments and bony congruence

Question 12

describe accessory posterior joint

Answer 12

extra articulation posterior to auricular surface
more common in males and elderly
unilateral or bilateral

Question 13

describe bipartate iliac bony plate

Answer 13

split appearance of iliac surface
more common in females
usually bilateral

Question 14

describe sacroiliac complex

Answer 14

iliac projection into recess in sacrum
more common in females
commonly bilateral

Question 15

describe semicircular defect

Answer 15

hallowing of sacral and iliac surface
commonly bilateral
may only affect sacral surface

Question 16

describe crescent ilium

Answer 16

superior ileum is crescent shaped
commonly bilateral

Question 17

describe isolated synostosis

Answer 17

sacroilium fusion
rare

Question 18

describe unfused ossification centre

Answer 18

alae centres present in joint space
rare
congenital

Question 19

describe dysmorphic sacrum

Answer 19

posterior sacral ridge protrudes into ileum
females and elderly mostly

Question 20

which ligaments may be affected by slouching

Answer 20

iliolumbar

Question 21

list the 4 types of SIJ dislocation

Answer 21

partial
Bilateral
pure SIJ
crescent fracture

Question 22

describe pure SIJ dislocation

Answer 22

all ligaments torn
sacrum completely seperated from ilium

Question 23

describe crescent fracture

Answer 23

crescent shaped fracture with dislocation

Question 24

list surgical fixation options for SIJ dislocation/fracture

Answer 24

iliosacral screws
anterior plates
osteosynthesis