Biomechanics of Hip and Pelvis

Question 1

What type of joint is sacroiliac Joint

Answer 1

compound joint: part plane synovial joint and part syndesmosis

Question 2

How mm wide are the SIJ joint

Answer 2

1-2mm wide

Question 3

Factors that provide stability to SIJ

Answer 3

Interlocking of articular surfaces
Advancing age partial synostosis (fusion) of joint takes place, reduce further movement
Supporting structures include thick, strong interosseous Posterior Sacroiliac ligaments
As well as Sacro-tuberous and sacrospinous

Question 4

Muscles that reinforce and stabilise SIJ

Answer 4

Muscles of the spine: Erector spinae, lumbar mutifiidis

Abdominal muscles: external &internal oblique, rectus abdominis, transversus abdominis
Latissimus Dorsi, iliacus and piriformis

Question 5

Kinematics of SIJ

Answer 5

Rotational Movement 1-4 degrees
Translational 1-2mm

Question 6

Nutation

Answer 6

Anterior tilt of the sacrum relative to the ilium

Sacral base- tilts anterior/inferior
Apex of Sacrum tilts posterior/superior

Question 7

Counternutation

Answer 7

Posterior tilts of the base of the sacrum relative to ilium
Sacral base- tits posterior/superior
Apex of Sacrum- tilts anterior and inferior

Question 8

Neck of Femur: Angle of Inclination what is it?

Answer 8

describes the angle within frontal plane and femoral neck and medial side of the femoral shaft

Question 9

Angle of Inclination at birth and adult?

Answer 9

At birth: 145
As an adult 125

Question 10

Coxa Vara?

Answer 10

smaller angle

Question 11

Coxa Valga?

Answer 11

Larger angle

Question 12

Positives of Coxa Vara

Answer 12

Increased moment arm for hip abductor force

Alignment may improve stability

Question 13

Negative of Coxa vara

Answer 13

Increased bending of moment arm
increases shear force across femoral neck

Decreases functional length of hip abductor muscles

Question 14

Positive of Coxa Valga

Answer 14

Decreased bending of moment arm
decreases shear force across femoral neck

Increased functional length of hip abductor muscle

Question 15

Negatives of Coxa Valga

Answer 15

Decreased moment arm for hip abductor force
Alignment may favour a joint dislocation

Question 16

Flexion/Extension of hip sagittal plane

Answer 16

flexion 120
extension 20

Question 17

Abduction/adduction hip frontal plane

Answer 17

abduct 40 adduct 25

Question 18

Rotation in neutral hip position horizontal plane

Answer 18

internal 35
lateral 45

Question 19

Anterior pelvic tilt results in

Answer 19

Hip flexion

Question 20

Muscles that assist in single leg stance

Answer 20

gluteus medius, gluteus minimus, tensor fasica lata

Question 21

Clinical? what does pelvis dropping called

Answer 21

Trendelenberg’s sign