Biomechanics of Hip and Pelvis

Question 1

Describe the sagittal plane of motion for the hip.

Answer 1

anterior/posterior tilt

Question 2

describe the frontal plane of motion for the hip.

Answer 2

left lateral pelvic tilt (left side moves upward)

right lateral pelvic tilt (right side moves upward)

Question 3

describe the transverse plane of motion for the hip.

Answer 3

left transverse pelvic tilt (left side moves posterior)

right transverse pelvic tilt (right side moves posterior)

Question 4

what is the angle of inclination formed by?

Answer 4

angle in teh FRONTAL plane formed by the axis of the head and neck of the femur and shaft of the femur

Question 5

what is the angle of inclination in infants?adults?

Answer 5

infants- 150 degree
adults- 125 degrees
(the angle of inclination decreases by 25 degrees from infancy to adulthood)

Question 6

what is a decrease in the angle of inclination called?

Answer 6

coxa vara (genu valgum)- distal femur is directed towards the midline and the knees are closer together

Question 7

what is an increase in teh angle of inclination called?

Answer 7

coxa valga (genu varum) - distal femur is directed away from the midline and the knees are farther apart

Question 8

what is the purpose of normal inclination angle?

Answer 8

allows abductors to function with a mechanical advantage as they counterbalance body weight in one-legged stance

Question 9

where should hip abductors be to achieve muscle stability which is maximum when the child begins to stand? (one-legged)

Answer 9

hip abductors should be as far laterally from the hip (fulcrum) to increase the lever arm

Question 10

what is alsberg’s angle?

Answer 10

(similar to angle of inclination) - angle formed by the line thru the epiphyseal plate of the neck of the femur and the long axis of the femur

Question 11

what is normal alsberg’s angle?

Answer 11

41 degrees

Question 12

an increase in alsberg’s angle would be called what? a decrease?

Answer 12

increase- coxa valga (genu varum)

decrease- coxa vara (genu valgum)

Question 13

what is the angle of declination?

Answer 13

angle in the TRANSVERSE plane formed by the axis of the neck of the femur and the transcondylar axis of the knee with the apex of teh angle lateral

Question 14

what is the angle of declination in infants? adults?

Answer 14

infant: 30-60 degrees of internal rotation
adults: 8-12 degrees of internal rotation

Question 15

what is femoral anteversion?

Answer 15

normal internal femoral shaft rotation for angle of declination

Question 16

Name the hip external rotators.

Answer 16

*mnemonic- go out and get some quality players
gluteus maximus
obturators
adductors
gemelli
sartorius
quadratus femoris
piriformis

Question 17

Name the internal hip rotators.

Answer 17

gluteus medius and minimus

Question 18

what is the normal fetal position?

Answer 18

(like buddha)
hips and knees flexed
hips externally rotated
legs and feet internally rotated

Question 19

what allows maximal rotation of hip in flexed position?

Answer 19

femoral anteversion

Question 20

what is teh angle of inclination?

Answer 20

angle created from the adducted position of the femur

Question 21

how do you calculate neutral femoral position (NFP)?

Answer 21

NFP = max. external rotation - (external rot+ internal rot/2)

Question 22

what does a negative value for NFP indicate?

Answer 22

there is more internal rotation than external rotation

Question 23

if NFP is the same with the hip flexed and extended, what does this indicate?

Answer 23

rotation is due to bony changes (in femur)

Question 24

if NFP is different btwn hip flexed and extended, what does this indicate?

Answer 24

rotatio is due to a soft tissue contracture

Question 25

what is the NFP for infants?

Answer 25

(3:1 ratio)
external- 60- 90 degrees
internal- 0-30 degrees

Question 26

what is the NFP for up to 1 y/o?

Answer 26

(2:1 ratio)
external- 50-60 degrees
internal- 30 degrees

Question 27

what is the NFP for up to 4y/o?

Answer 27

(1:1 ratio)
external- 45 degrees
internal- 45 degrees

Question 28

which ligament is tightened with the hip flexed?

Answer 28

ischiofemoral ligament

Question 29

what could be a cause of decreased internal hip ROM (same as increased external hip ROM)?

Answer 29

shortened or taut ischiofemoral ligament

Question 30

which ligament is tightened with hip extended?

Answer 30

iliofemoral, puboscapular, ligamentum teres

Question 31

what could be the cause of decreased external hip ROM (same as increased internal hip ROM)?

Answer 31

shortened or taut iliofemoral, puboscapular, ligamentum teres

Question 32

what is the needed amt of hip flexion/extension?

Answer 32

flexion- at least 120-130

extension- 0-20

Question 33

what is the needed amt of hip abduction/adduction?

Answer 33

hip abudction- 40-45

hip adduction- 20-25

Question 34

what are you testing when you have patient supine, flex the hip and knee to 90 and slowly rotate the leg outwards (externally) as you gradually extend the knee?

Answer 34

testing medial hamstring tightness

-examiner will be unable to achieve 160 degrees of knee extension

Question 35

what are you testing when you have patient supine, flexed hip and knee, and slowly rotate the knee internally as you gradually extend the knee?

Answer 35

testing lateral hamstring tightness