hip Flashcards
3 DOF (rotations)
Flex/ext
Abd/add
IR/ER
3 DOF arthrokinematic (translations)
Ant/post
Sup/Inf
Traction/compression
Version
Angle of head femur with respect to shaft in the transverse plane
Angle of inclination
Angle between head & neck and shaft femur in frontal plane
Alpha angle
Size between femoral head with respect to acetabulum
Coxa vera
Hip bends inward (genu valgum)
<125 degrees
Coxa valga
Hip bends upwards (genu varum)
> 125 degrees
Range normal values for angle inclination:
Infants
Adults
Elderly
Infants: 165-170
Adults: 125
Elderly: <120
Decreases 2-8 degrees per yr
Why does angle inclination dec?
Gravity
Pelvic width (women)
Puberty
Wt bearing
Femur lat side (convex) resists what type of load?
Traction
Femur med side (concave) resists what type of load?
Compression
What is the effect of weight-bearing on the femoral shaft and neck?
Traction, compression
Inc angle inclination, dec bending mvt
Coxa valga dec bending moment of femur
Coxa vera inc bending moment (inc moment arm = risk for fracture)
Trabecular configuration of the proximal femur main system:
Arcuate bundle: resists bending moment
Vertical bundle: resists compressive moment
Loc: head neck femur
Trabecular configuration of the proximal femur accessory system:
Reinforces muscle attachment sites
First & second bundle
Loc: between neck shaft (greater trochanter)
What are the effects of femoral inclination on bending moment?
Inc angle inclination, dec bending moment —> dec risk fracture (Coxa valga)
Coxa vera trade off
Favors joint stability
Inc risk hip fracture (inc bending moment)
(Hip abd force= more advantageous)
(Dec func length)
Coxa valga trade off
Favors dislocation
Dec risk fracture (dec bending moment)
(Hip abd force= dec mechanical advantage)
(Inc func length)
Version
Twist of femoral shaft
Bisects head neck femur and frontal plane
(Typically viewed from above)
Angle anteversion normal range
Range: 8-30 degrees
Avg: 15 degrees
Excessive femoral anteversion
> 30 degrees
Neck points anteriorly