Hips Flashcards
Angle of inclination
frontal plane angle b/w femoral neck and femoral shaft
normal is 125°
Coxa vara
angle between shaft and neck is <110°
congenital or caused by injury
can cause shorter limb
Coxa valga
angle between shaft and neck >135
cerebral palsy
can cause a long limb
Compared to normal, in which scenario will the hip abductors have to produce more force to generate the same level of torque?
Coxa valga
moment arm is smaller vs a normal hip
Femoral Torsion
Transverse plane angle btwn medial/lateral axis and the femoral neck
normal angles range from 8-20° in front of medial/lateral axis
Femoral Anteversion
angle btwn horizontal and neck in transverse plane >20°
causes in-toeing because it positions the head better
Femoral Retroversion
angle btwn horizontal and neck in transverse plane <8°
out-toeing
Why does excessive anteversion or retroversion cause toe-in or toe-out gait?
you compensate to increase congruency of head with acetabulum
Coxa valga and excessive anteversion are particularly common in individuals with cerebral palsy. Why?
decreased weight bearing causes the head to turn inwards
Congruent position of hip
abduction
flexion @90°
ER
Ligamentum Teres
runs between acetabulum and fovea
function is unknown in adults, can be taut in flex, add, IR
improves hip stability in newborns
Acetabular Labrum
Restricts al motions
acts as a suction, grips and stabilizes femoral head
limited vascular supply
Center Edge Angle
Degree to which the acetabulum covers the femoral head in frontal plane
25-35°
Low center edge angle
indicates less contact area and greater joint stress
higher dislocation risk
High center edge angle
Increases chance of impingement
Acetabular Anteversion Angle
degree to which acetabulum faces anteriorly in transverse plane
20°
higher angle = subluxation, instability
Hip joint capsule
resists flexion/extension
extremely strong, contributes to joint stability
thicker Ant & Sup
thinner post/inf
Illiofemoral ligament
resists extension, ER, abduction
strongest
resists further hip extension when standing
Pubofemoral ligament
resists abduction, extension, ER
blends into iliofemoral
Ischiofemoral ligament
Moderate resistance to IR
Some resistance to extension & adduction
spiral formation, weakest formation
Closed pack position of hip
hip extension
hip abduction
hip IR
stretches all capsular ligaments
Degrees of freedom
3, axis is through the femoral head