Overview of the SIJ/FAJ, Stabilizers, Pathology

Question 1

Bones of the SIJ

Answer 1

sacrum

ilium of the pelvis

• asymmetry in the joint is very common–> Morphology and mobility very different from person to person

–> normal adaptations and anatomical variation

Question 2

SIJ type

Answer 2

planar joint

articulation: auricular surface of the ilium with auricular surface of the sacrum

there can be a lot of overlap between the inominate and the sacrum

Question 3

Motion of the sacrum on the innominate:

Answer 3

** the sacrum is moving on the very stationary innominate

NUTATION
-superior part of the sacrum moves anterior inferior
-infeiror part of hte sacrum moves superior/post
* nutation occurs in standing due to weight from lumbar spine–> more stabilization from ligaments (sacrospinous, sacrotuberous) that prevent further motion of the sacrum on the innominate
-INF/POST glide of sacrum on innominate

COUNTER NUTATION
-top of sacrum moves posteriorly
-bottom of sacrum moves anteriorly
-ANT/SUP glide of the sacrum on the innominate

Question 4

Static stabilizers of SIJ

Answer 4

sacrospinous lig

sacrotuberous lig

Question 5

dynamic stabilizers of the SIJ

Answer 5

• create pressure across the joint

**transversus abdominis
glut max
fascia
latissimus dorsi
obliques

Question 6

The primary function of the SIJ

Answer 6

distribute forces from the trunk through the ring of the pelvis

Question 7

HIP (FAJ) characteristics

Answer 7

type: synovial ball and socket

articulation: head of the femur with lunate surfacce of acetabulum

Question 8

Angle of inclination

Answer 8

angle of femoral head and neck on shaft of femur

normal: 125 deg

coxa vara: <125
-deepening effect
-genu valgum (knock knees)

coxa valga: > 125
-genu varum (bow legged)

Question 9

Femoral osseous angles- angle of inclination has joint reaction force and muscle demand implications

Answer 9

COXA VARA: <125
-good: increased hip abductor moment arm, joint stability may be better
-bad: increased shear force across femoral neck due to increased bending moment arm, decreased functional length of the hip abductor muscles

COXA VALGA: > 125
-good: decreased shear force across femoral neck, increased functional length of the hip abductor muscles
-bad: decreased moment arm for hip abductor force, * alignment may favor joint dislocation (shallower socket)

Question 10

Angle of torsion def:

Answer 10

the angle between the axis of the femoral head and the axis of the femoral condyles at the knee

–> angle can lead to anteversion or retroversion

NORMAL: 8-15 degrees

Anteversion: >15 deg
-in-toeing occurs to keep optimal length-tension relationship of muscles and alignment of the femoral head in the acetabulum

Retroversion: <8 degrees
-out-toeing occurs to keep optimal length-tension relationship of muscles and alignment of the femoral head in the acetabulum

Question 11

What is the lunate surface of the acetabulum closed off by?

Answer 11

the transverse acetabular ligament

–> ligament of the head of the femur comes off of
–> carries artery of the ligament of the head of the femur

Question 12

Characteristics of the labrum of the hip joint (acetabular labrum)

Answer 12

The labrum extends on both sides to the outside and inside where it has a junction with the articular surface covering the lunate surface

Question 13

Function of the labral seal

Answer 13

MAY provide stability; there is conflicting evidence

protects the articular cartilage on the head of the femur with pressurization that occurs when the femoral head pushes up against the labrum and there is synovial fluid in between

–> synovial fluid barrier helps to maintain nutrition and lubrication of the articular cartilage as well

Question 14

Labral tears characteristics

Answer 14

very common- 70% of asymptomatic individuals have labral pathology

-need to evaluate the utility of repair with symptoms

Question 15

Function of the hip joint capsule

Answer 15

encapsulates the joint
provides stability

Question 16

Capsular ligaments of the hip:

Answer 16

iliofemoral
ischiofemoral
pubofemoral

Question 17

Hip Osteokinematics and Arthrokinematics hip flexion

Answer 17

spin with slight inferior and posterior glide at terminal motion

Question 18

Hip Osteokinematics and Arthrokinematics hip extension

Answer 18

spin with slight anterior and superior glide at terminal motion

Question 19

Hip Osteokinematics and Arthrokinematics external rotation

Answer 19

anterior glide

Question 20

Hip Osteokinematics and Arthrokinematics internal rotation

Answer 20

posterior glide

Question 21

Hip Osteokinematics and Arthrokinematics adduction

Answer 21

superior glide

Question 22

Hip Osteokinematics and Arthrokinematics abduction

Answer 22

inferior glide

Question 23

Notes about Hip Osteokinematics and Arthrokinematics

Answer 23

The hip joint glides away from the portion of the capsule that is the tightest

The whole capsule becomes taut at end range

** any glide will allow for increased motion due to circumferential nature of the capsule

Question 24

What motions would you avoid after anterior approach to hip replacement?

Answer 24

all ligs taut in extension
2 of 3 ligs taut in ER
the capsule is also taut in ER

LIMIT:
-extension, ER for 2 weeks at a minimum