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Unit 3 Biomechanics Winter 2024 > Hip region > Flashcards

Hip region Flashcards

1
Q

What is the angle of inclination for the hip?

A
  • angle of the neck of the femur in the frontal plane
  • normal = 125 degrees
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2
Q

What is coxa vera and coxa valga?

A
  • Coxa vera: less than 125 degrees of AoI; distal segment toward midline
  • Coxa valga: greater than 125 degrees of AoI; distal segment away from midline
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3
Q

What is the angle of torsion?

A
  • rotation/twist between the femoral neck and shaft (femoral torsion)
  • normal = 15 degrees of anteversion
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4
Q

What is anteversion of the hip?

A
  • normal = 15 degrees
  • excessive = greater than 15 degrees
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5
Q

What is considered retroversion of the hip?

A
  • less than 15 degrees
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6
Q

What are some potential consequences of excessive femoral anteversion?

A
  • dislocation risk
  • joint incongruency
  • increased joint contact stress
  • wear on cartilage and labrum
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7
Q

Why does the “in-toeing” gait pattern occur?

A
  • compensation for excessive anteversion by internally rotating the hip
  • increases moment arm for hip abductors
  • shortens ligaments & limits hip ER
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8
Q

Why is it a good thing that the thickest articular cartilage of the acetabulum is in the superior anterior region?

A
  • this area has the highest joint forces while walking
  • it increases contact area which reduces contact pressure
  • keeps stress in physiological tolerable levels
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9
Q

What are the special qualities of the acetabular labrum?

A
  • grips femoral head, deepens socket
  • maintains interarticular pressure (suction-seal)
  • keeps fluid from leaking out (synovial fluid) which is a fluid seal
  • reduces friction
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10
Q

How does the hips close-packed position compare to the position of most articular congruence?

A

CPP: full ext. slight IR, & abduction -> most ligaments taut
MAC: 90 degrees flexed, moderate abduction, & ER

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11
Q

What is the normal position of the acetabulum?

A

inferior and anterior
- center edge angle (degree in which it covers femoral head) = 25-35 degrees
- acetabular anteversion angle (angle it faces anteriorly) = 20 degrees

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12
Q

What happens if there is a too low or too high center edge angle?

A
  • Too low: reduced coverage = increased dislocation, sublux, instability
  • Too high: increased coverage = impingement, injury
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13
Q

What happens if there is excessive or retroversion of the acetabular anteversion angle?

A
  • excessive = reduces femoral head coverage
  • retroversion = increases femoral head coverage
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14
Q

What are the arthrokinematics for femoral-on-pelvic flexion

A

femoral head spin

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15
Q

What are the arthrokinematics for femoral-on-pelvic extension

A

femoral head spin

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16
Q

What are the arthrokinematics for femoral-on-pelvic abduction

A

femoral head:
- rolls superior
- slides inferior

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17
Q

What are the arthrokinematics for femoral-on-pelvic adduction

A

femoral head:
- rolls inferior
- slides superior

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18
Q

What are the arthrokinematics for femoral-on-pelvic external rotation

A

femoral head:
- rolls posterior
- slides anterior

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19
Q

What are the arthrokinematics for femoral-on-pelvic internal rotation

A

femoral head:
- rolls anterior
- slides posterior

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20
Q

What are the arthrokinematics for pelvic-on-femoral flexion

A

acetabulum spins

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21
Q

What are the arthrokinematics for pelvic-on-femoral extension

A

acetabulum spins

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22
Q

What are the arthrokinematics for pelvic-on-femoral abduction

A

acetabulum rolls and slides superior

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23
Q

What are the arthrokinematics for pelvic-on-femoral adduction

A

acetabulum rolls and slides inferior

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24
Q

What are the arthrokinematics for pelvic-on-femoral external rotation

A

acetabulum rolls and slides posterior

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25
Q

What are the arthrokinematics for pelvic-on-femoral internal rotation

A

acetabulum rolls and slides anterior

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26
Q

Where does the AoR run for IR/ER?

A
  • from femoral head to middle of knee joint
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27
Q

What ligaments are stretched with hip extension?

A
  • iliofemoral
  • anterior capsule
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28
Q

What ligaments are stretched with hip abd, ext, and ER?

A
  • pubofemoral
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29
Q

What ligaments are stretched with hip IR and 10-20 degrees of abduction?

A
  • ischiofemoral
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30
Q

How does ipsidirectional lumbopelvic rhythm differ from contradirectional lumbopelvic rhythm?

A

Ipsidirectional: spine and pelvis rotate in same direction
Contradirectional: spine and pelvis rotate in opposite directions

this allows the trunk above lumbar to remain stationary as pelvis rotates and is used during walking

31
Q

Describe spinal movement for pelvic-on-femoral flexion

A
  • anterior rotation of about 30 degrees pelvic tilt
  • extension of lumbar spine
32
Q

Describe spinal movement for pelvic-on-femoral extension

A
  • posterior rotation of about 15 degrees pelvic tilt
  • flexion of lumbar spine (reduce lordosis)
33
Q

Describe spinal movement for pelvic-on-femoral abduction

A
  • pelvis hikes on contralateral side (about 30 degrees)
  • lumbar spine laterally flexes toward contralateral hike

EX: R hip abd = L hip iliac crest hiking and lateral flex of spine to the left

34
Q

Describe spinal movement for pelvic-on-femoral adduction

A
  • pelvis hikes on ipsilateral side (about 25 degrees)
  • lumbar spine laterally flexes toward ipsilateral hike
35
Q

What is “internal snapping hip syndrome”?

A
  • iliopsoas abrasion from crossing inferior hip & femoral head
  • usually during hip flexion
36
Q

What are the hip flexors?

A

Primary:
- psoas major
- iliacus
- sartorius
- TFL
- rectus femoris
- pectineus

Secondary:
- adductor longus
- adductor brevis
- gracilis
- gluteus minimus

37
Q

What are the hip adductors?

A

Primary:
- pectineus
- adductor longus
- gracilis
- adductor brevis
-adductor magnus

Secondary:
- bicep femoris (LH)
- glute max
- quadratus femoris
- obturator externus

38
Q

What are the internal rotators of the hip?

A
  • glute med & min
  • TFL
  • adductor longus/brevis
  • pectineus
39
Q

What are the hip extensors?

A

Primary:
- glute max
- bicep femoris (LH)
- semitendinosus
- semimembranosus
- adductor magnus

Secondary:
- glute med

40
Q

What are the hip abductors?

A

Primary:
- glute med & min
- TFL

Secondary:
- piriformis
- sartorius
- rectus femoris
- glute max

41
Q

What are the external rotators of the hip?

A

Primary:
- piriformis
- obturator internus
- superior gemellus
- inferior gemellus
- quadratus femoris
- glute max

Secondary:
- glute med & min
- obturator externus
- sartorius
- bicep femoris (LH)

42
Q

What position is the worst torque potential for the abductors of the hip?

A
  • 40 degrees abduction
  • causes active insufficiency
43
Q

What position is the best torque potential for the abductors of the hip?

A
  • slightly adducted (elongated)
  • occurs in stance phase of gait
44
Q

Explain the force couple involved with anterior tilting of the pelvis

A
  • sartorius depressed ASIS
  • iliopsoas increases lumbar lordosis
  • erector spinae elevates coxa
45
Q

Explain the force couple involved with posterior tilting of the pelvis

A
  • rectus abdominis elevates pubic symphysis
  • glute max depresses posterior iliac crest
  • hamstrings pull ischial tuberosity inferior
46
Q

Explain how the adductors operate in the sagittal plane

A
  • adductor magnus (post. fibers) extends the hip regardless of position
  • @ 40-70 degrees of flexion other adductors lose torque potential
  • outside of 40-70 degrees of flexion there is better leverage for flex/ext
47
Q

What happens to the internal rotators (& some external rotators) when the hip is flexed to 90 degrees?

A
  • torque potential increases from IR’s
  • moves line of force from parallel to almost perpendicular
48
Q

How is it that some of the adductors can internally rotate the hip?

A
  • the femur has a natural bow to it
  • although the adductors attach to the posterior aspect of the femur they are oriented in front of the AoR for IR/ER
  • their line of pull creates an internal rotational force in anatomical neutral
49
Q

Which muscle is most active in resisting a forward lean in standing and why?

A

Hamstrings:
- moment arm increases
- stretched across 2 joints which creates passive tension
- glute max held in neutral by nervous system for more powerful hip ext.

50
Q

List the hip muscle groups in order from greatest torque potential to least

A

Sagittal: extensors > flexors
Frontal: adductors > abductors
Horizontal: IR’s > ER’s

Strongest to weakest

51
Q

What are the impairments with a hip flexion contracture on standing posture with joints above and below the hip?

A
  • very tight iliofemoral ligament and psoas major
  • hip extensors shortened
  • leads to degeneration where cartilage doesn’t overlap (all joints involved)
  • joint compression increases
  • leads to slight dorsiflexion, knee flexion, and increased lordosis
52
Q

How can a patient with a spinal cord injury attain an upright posture without the use of hip extensors?

A
  • they lean pelvis & trunk posteriorly which moves line of gravity posterior to the hips
  • this creates hip extension torque
  • stretches iliofemoral ligaments which creates a passive flexion torque
53
Q

Explain the mechanisms of injury with a labral pathology

A
  • rotation, repetitive, end-ROM movements
  • hip dislocations
  • strenuous lifting/pulling from full squat
  • tears from compression, tension, shearing
  • Idiopathic, trauma, excessive wear
54
Q

What is Femoral-Acetabular impingement (FAI)?

A
  • repeated contact b/w femur & acetabulum
  • causes damage to labrum, sub-cartilage, and sub-chondral bone
55
Q

What is a CAM lesion?

A
  • femoral head overgrowth
56
Q

What is a Pincer lesion?

A
  • acetabular overgrowth
57
Q

How is FAI related to OA?

A
  • repeated outside-in trauma from bony impingement
  • trauma to cartilage from altered arthrokinematics
  • failure of damaged labrum to provide a fluid seal to joint
58
Q

What is Developmental Dysplasia of the Hip (DDH)?

A
  • abnormal growth/development resulting in a misshaped proximal femur
  • starts at birth or 1st few years of life
  • dislocation can occur frequently
  • femoral head doesn’t sit in acetabulum
59
Q

Describe the pathomechanics involved in greater trochanteric pain syndrome

A
  • degeneration of distal tendon attachment of glute med and min
  • could include bursitis (worsens w/ high, sustained, repetitive use of adductors
  • tears, abrasions of tendons of glute med/min
60
Q

In what way is greater trochanteric pain syndrome similar to rotator cuff syndrome of the shoulder?

A
  • both usually show degeneration on the underside of the tendon
  • pain usually insidious & chronic
  • tendon compression
61
Q

What is the difference between the trendelenburg sign and the compensated trendelenburg sign?

A

TS: hip drops on the contralateral hip
CTS: contralateral hip raises up, trunk leans toward ipsilateral standing leg

62
Q

What is usually the cause of TS or CTS?

A
  • hip abductor weakness
  • strengthen hip abduction & Ext, IR, or ER
63
Q

Explain how using a cane on the opposite side can reduce the joint reaction forces on the hip

A
  • reduces abductor demand
  • produces torque in same rotary direction as abductors
64
Q

Explain how carrying a heavy load on the same side reduces joint reaction forces in the hip

A
  • helps counteract the forces the abductors need to keep body weight upright
  • helps abductors do their job with less work and JRF
65
Q

What advice can we give our patients to reduce JRF at the hip?

A
  • carry lighter loads
  • use a cane on the contralateral side
  • use bilateral carrying techniques
  • carry heavier objects on ipsilateral side
  • use a cane on contra side and carry on ipsilateral side
66
Q

What are the positives and negatives of Coxa Varus Osteotomy?

A

Positives:
- increased moment arm for hip abductors
- alignment may improve joint stability

Negatives:
- increased bending moment arm increases bending moment torque = increases shear force across femoral head
- decreased functional length of hip abductors

67
Q

What are the positives and negatives of Coxa Valgus Osteotomy?

A

Positives:
- decreased bending moment arm decreases bending moment torque = decreases shear force across femoral neck
- increased functional length of hip abductors

Negatives:
- decreased moment arm for hip abductors
- alignment may favor dislocation

68
Q

What are some risk factors involved in hip fractures?

A
  • age (70+)
  • osteoporosis
  • decreased bone density
  • history of falling
  • physical inactivity
69
Q

What are some conditions that can lead to hip arthritis?

A
  • FAI
  • CAM/Pincer impingements
  • labral tears
  • inadequate joint forces

moderate PA helps w/ prevention

70
Q

What are the post-op precautions for a posterior approach total hip replacement?

A
  • no hip flexion past 90 degrees
  • no hip adduction pasted midline
  • no hip internal rotation
71
Q

What are the AAOS norms for hip flexion and extension?

A

Flexion: 120

Extension: 20

72
Q

What are the AAOS norms for hip abduction and adduction?

A

Abduction: 45

Adduction: 30

73
Q

What are the AAOS norms for IR and ER?

A

IR: 45

ER: 45

Unit 3 Biomechanics Winter 2024 (8 decks)

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