Biomechanics Hip Flashcards
hip
-primary functions
supports the head, arms, and trunk
static erect postures
dynamic postures
-ambulation, running, stair climbing
hip degrees of freedom
3
- abduction/adduction
- flexion/extension
- IR/ER
hip arthrokimenatics
- type of joint
- movement rule
ball and socket
convex on concave (glide and roll opposite directions)
hip loose pack position
35 degrees flexion/abduction
slight external rotation
hip closed pack position
maximum extension
maximum IR
maximum abduction
hip articular components
articular surfaces -acetabulum -head of femur joint capsule -thick and tough
hip capsular ligaments
-anterior or posterior
iliofemoral or "Y" ligament -anterior pubofemoral -anterior ischiofemoral -posterior
acetabular labrum
- what is it
- where does it accach?
- which portions most innervated
- blood supply mostly _____
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)
labrum functions
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
acetabulum is positioned in what position (relative to cardinal planes)
lateral
inferior
anterior
why does the upper portion of the acetabulum form an overhang - purpose
sustains highest forces through femoral head
where is the articular cartilage thickest for the femoral head and acetabulum
superiorly
where is the one point the femoral head is not covered in articular cartilage
fovea
-ligamentum teres attachment
in which plane do the following occur
- angle of inclination
- angle of torsion
inclination
-frontal
torsion
-transverse
angle of inclination in
- infants
- adults
- elderly
infants -150 adults -125 elderly -120
do females have a greater or smaller angle of inclination than men?
-why
smaller
-greater pelvic width
coxa valga and coxa vara angles
valga
-angle > 125
vara
-<125
what knee posture is associated with
- coxa vara
- coxa valga
coxa vara and genu valga
coxa valga and genu vara
angle of torsion
-what two structures is the measurement between?
long axis of femoral head
transverse axis of femoral condyles
angle of torsion
-typical measurement
adults - around 12
can range from 8 to 25
anteversion and retroversion
- measurement
- consequence
anteversion -angle > 12 -IR of femur retroversion -angle < 12 -ER of femur
cantilever system of the hip
- what is it?
- purpose
forces transmitted to the femoral shaft through the femoral neck
gives us a larger moment arm
significance of long femoral neck
- benefit
- negative
improves mechanical advantage of hip abductor muscles
causes femoral neck to be susceptible to fractures with bone weakening
hip joint capsule
- what is it’s shape?
- attaches to…
shaped like a cylindrical sleeve
attaches to
-entire periphery of the acetabulum via labrum
-neck of femur
“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
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
ligamentum teres
-function
does not function to support joint
serves as a guide for obturator artery branch traveling to fovea on head of femur
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
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
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
primary muscles used during unilateral stance that act in the frontal plane
ipsilateral hip abductors (glut med)
contralateral erector spinae
