Biomechanics Hip Flashcards

1
Q

hip

-primary functions

A

supports the head, arms, and trunk
static erect postures
dynamic postures
-ambulation, running, stair climbing

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2
Q

hip degrees of freedom

A

3

  • abduction/adduction
  • flexion/extension
  • IR/ER
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3
Q

hip arthrokimenatics

  • type of joint
  • movement rule
A

ball and socket

convex on concave (glide and roll opposite directions)

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4
Q

hip loose pack position

A

35 degrees flexion/abduction

slight external rotation

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5
Q

hip closed pack position

A

maximum extension
maximum IR
maximum abduction

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6
Q

hip articular components

A
articular surfaces
-acetabulum
-head of femur
joint capsule
-thick and tough
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7
Q

hip capsular ligaments

-anterior or posterior

A
iliofemoral or "Y" ligament
-anterior
pubofemoral
-anterior
ischiofemoral
-posterior
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8
Q

acetabular labrum

  • what is it
  • where does it accach?
  • which portions most innervated
  • blood supply mostly _____
A

ring of fibrocartilage that encircles the acetabulum
attachments
-rim of acetabulum
-transverse acetabular ligament
anterior and superior portions most innervated
blood supply mostly peripheral (outer 1/3)

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9
Q

labrum functions

A

shock absorption and pressure distribution
-increases surface area of acetabulum by 20%
-distributes load and decreases contact stress
joint lubrication
-maintains synovial fluid within articular cartilage
–allows for some load to be borne by fluid pressurization
enhances joint stability

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10
Q

acetabulum is positioned in what position (relative to cardinal planes)

A

lateral
inferior
anterior

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11
Q

why does the upper portion of the acetabulum form an overhang - purpose

A

sustains highest forces through femoral head

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12
Q

where is the articular cartilage thickest for the femoral head and acetabulum

A

superiorly

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13
Q

where is the one point the femoral head is not covered in articular cartilage

A

fovea

-ligamentum teres attachment

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14
Q

in which plane do the following occur

  • angle of inclination
  • angle of torsion
A

inclination
-frontal
torsion
-transverse

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15
Q

angle of inclination in

  • infants
  • adults
  • elderly
A
infants
-150
adults
-125
elderly
-120
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16
Q

do females have a greater or smaller angle of inclination than men?
-why

A

smaller

-greater pelvic width

17
Q

coxa valga and coxa vara angles

A

valga
-angle > 125
vara
-<125

18
Q

what knee posture is associated with

  • coxa vara
  • coxa valga
A

coxa vara and genu valga

coxa valga and genu vara

19
Q

angle of torsion

-what two structures is the measurement between?

A

long axis of femoral head

transverse axis of femoral condyles

20
Q

angle of torsion

-typical measurement

A

adults - around 12

can range from 8 to 25

21
Q

anteversion and retroversion

  • measurement
  • consequence
A
anteversion
-angle > 12
-IR of femur
retroversion
-angle < 12
-ER of femur
22
Q

cantilever system of the hip

  • what is it?
  • purpose
A

forces transmitted to the femoral shaft through the femoral neck
gives us a larger moment arm

23
Q

significance of long femoral neck

  • benefit
  • negative
A

improves mechanical advantage of hip abductor muscles

causes femoral neck to be susceptible to fractures with bone weakening

24
Q

hip joint capsule

  • what is it’s shape?
  • attaches to…
A

shaped like a cylindrical sleeve
attaches to
-entire periphery of the acetabulum via labrum
-neck of femur

25
"accordion-like" folds found on inferior and superior aspects of capsule - what are they called? - what's their purpose
frenula (synovial folds) | required to permit full abduction and adduction ROM
26
hip capsule ligaments - do they wrap in CW or CCW direction - why this direction? - consequence
CW direction direct result of development of upright posture primary reason why humans have extremely limited hip hyperextensiion
27
ligamentum teres | -function
does not function to support joint | serves as a guide for obturator artery branch traveling to fovea on head of femur
28
closed chain motion of the hip and the corresponding open chain motion
``` anterior/posterior pelvic tilt -flexion/extension of hip lateral pelvic tild -abduction/adduction of hip anterior and posterior pelvic rotation -IR/ER ```
29
double-leg stance - where is COM - muscle action required - static structures required
whole body COM acts at S2 and is midline no muscle activity required to maintain upright, neutral posture at the hip ligaments and joint capsule provide stability
30
trendelenburg sign | -what occurs at the pelvis, femur, and lumbar spine (standing on R leg)
``` pelvis -contralateral (left) lateral tilt femur -ipsilateral (R) adduction lumbar spine -ipsilateral (R) lateral flexion ```
31
primary muscles used during unilateral stance that act in the frontal plane
ipsilateral hip abductors (glut med) | contralateral erector spinae