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2 Biomechanics > Hips > Flashcards

Hips Flashcards

1
Q

Angle of inclination

A

frontal plane angle b/w femoral neck and femoral shaft
normal is 125°

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2
Q

Coxa vara

A

angle between shaft and neck is <110°
congenital or caused by injury
can cause shorter limb

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3
Q

Coxa valga

A

angle between shaft and neck >135
cerebral palsy
can cause a long limb

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4
Q

Compared to normal, in which scenario will the hip abductors have to produce more force to generate the same level of torque?

A

Coxa valga
moment arm is smaller vs a normal hip

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5
Q

Femoral Torsion

A

Transverse plane angle btwn medial/lateral axis and the femoral neck
normal angles range from 8-20° in front of medial/lateral axis

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6
Q

Femoral Anteversion

A

angle btwn horizontal and neck in transverse plane >20°
causes in-toeing because it positions the head better

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7
Q

Femoral Retroversion

A

angle btwn horizontal and neck in transverse plane <8°
out-toeing

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8
Q

Why does excessive anteversion or retroversion cause toe-in or toe-out gait?

A

you compensate to increase congruency of head with acetabulum

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9
Q

Coxa valga and excessive anteversion are particularly common in individuals with cerebral palsy. Why?

A

decreased weight bearing causes the head to turn inwards

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10
Q

Congruent position of hip

A

abduction
flexion @90°
ER

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11
Q

Ligamentum Teres

A

runs between acetabulum and fovea
function is unknown in adults, can be taut in flex, add, IR
improves hip stability in newborns

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12
Q

Acetabular Labrum

A

Restricts al motions
acts as a suction, grips and stabilizes femoral head
limited vascular supply

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13
Q

Center Edge Angle

A

Degree to which the acetabulum covers the femoral head in frontal plane
25-35°

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14
Q

Low center edge angle

A

indicates less contact area and greater joint stress
higher dislocation risk

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15
Q

High center edge angle

A

Increases chance of impingement

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16
Q

Acetabular Anteversion Angle

A

degree to which acetabulum faces anteriorly in transverse plane
20°
higher angle = subluxation, instability

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17
Q

Hip joint capsule

A

resists flexion/extension
extremely strong, contributes to joint stability

thicker Ant & Sup
thinner post/inf

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18
Q

Illiofemoral ligament

A

resists extension, ER, abduction
strongest
resists further hip extension when standing

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19
Q

Pubofemoral ligament

A

resists abduction, extension, ER
blends into iliofemoral

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20
Q

Ischiofemoral ligament

A

Moderate resistance to IR
Some resistance to extension & adduction
spiral formation, weakest formation

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21
Q

Closed pack position of hip

A

hip extension
hip abduction
hip IR

stretches all capsular ligaments

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22
Q

Degrees of freedom

A

3, axis is through the femoral head

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23
Q

Sagittal plane

A

medial/lateral axis

24
Q

Frontal plane

A

A/P axis

25
Q

Transverse plane

A

Vertical axis
most of axis is outside of femur

26
Q

Sagittal plane Pelvis on femur

A

anterior and posterior pelvic tilt

27
Q

Frontal plane Pelvis on femur

A

abduction/hip hike
adduction/pelvic drop

28
Q

Transverse plane Pelvis on femur

A

internal rotation and external rotation

29
Q

Flexion/Extension movement of femoral head

A

SPIN, in closed chain or open chain

30
Q

Elevation of hip closed chain

A

Roll and slide are superior
reference hip is the one technically going DOWN

31
Q

Hip drop closed chain

A

Roll and slide are inferior
reference hip is the one technically going UP

32
Q

Hip Flexors

A

Anterior compartment
illiopsoas, rectus femoris, sartorius, adductor longus, pectineus, TFL

33
Q

What happens to the moment arm of the iliopsoas when the muscle flexes to 90°?

A

moment arm increases, more force production is possible

34
Q

Prominent femur on pelvis flexor

A

iliopsoas

35
Q

Hip flexion often requires co-activation of hip flexor and abdominal muscles. Why?

A

the rectus abdominus helps to pull up in the same direction as the rectus femoris

in contrast, psoas major and illacus will try to do flexion, causing anterior tilt and lordosis

36
Q

Hip extensors

A

posterior compartment
gluteus max, hamstrings, adductor magnus

37
Q

Is hip extensor torque greater with the knee flexed or extended?

A

Flexing knee to 90° causes the hamstrings to decrease in length, decreasing the tension, overall decreasing how much force the hamstrings can produce

38
Q

Which hip extensors help control forward trunk flexion?

A

hamstring MA increase with increasing flexion
glut max MA decreases with increasing flexion

39
Q

Hip abductors

A

gluteus medius, gluteus minimus, TFL

40
Q

Hip abductor muscle function

A

MA of abductors is 1/2 of MA from body weight. during standing, JRF is 2x body weight.
Abductors case a negative torque, in contrast to body weight

41
Q

Greatest angle of hip abductor torque

A

10°
earlier muscle activation of abductors means that less force will be produced from adductors. Important for hip stability

42
Q

Hip adductors

A

adductor group
pectineus
gracilis

adductor magnus is a strong adductor in any position

43
Q

0-40° hip adductors

A

work as hip flexors
in front of axis

44
Q

40-70° hip adductors

A

little torque production
in line with axis

45
Q

70-100° hip adductors

A

work as hip extensors
behind axis

46
Q

Hip Internal Rotators

A

no primary hip internal rotators
glute med, glute min, TFL, pectineus, add longus/brevis

47
Q

Is gluteus medius a stronger internal rotator in neutral or in hip flexion?

A

changes orientation of moment arm from to parallel (not flexed) to perpendicular (flexed). Increases moment arm when hip is flexed

48
Q

Hip external rotators

A

gluteus maximus, piriformis, gemelli, obturator internus, quadratus femoris

49
Q

How does hip external rotation torque change with hip flexion at 90°?

A

G. max, piriformis = become IR
obturator internus = stays ER, worse MA
quadratus femoris, obturator externus = increase ER MA

50
Q

IR showed dramatic increase from ___ to _____

A

supine knee flexed to seated

51
Q

ER showed modest increase from ____ to ____

A

supine knee flexed to seated

52
Q

Is hip rotation PROM influenced by hip position?

A

less ROM from sitting vs prone
major ligaments lax in flexion, meaning limitation would be capsular

53
Q

Femoroacetabular Impingement (FAI)

A

Large femoral neck or portion of acetabulum is hanging over head = congenital
high center edge angle or acetabular retroversion
coxa vara

54
Q

Hip labral tears

A

Chronic wear and tear
traumatic injury
FAI (increases stress on labrum)
Coxa vara and valga
Excessive anteversion or retroversion

55
Q

Hip osteoarthritis

A

breakdown of articular cartilage
chronic wear and tear
coxa valga or vara
excessive anteversion or retroversion
FAI
labral tears

increased contact stress at joint, caused by JRF, contact area, center edge/anteversion

2 Biomechanics (9 decks)

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