hip joint - kines Flashcards
hip joint articulation
b/w the acetabulum of the pelvis proximally and the head of the femur distally
the hip joint is also called the
coxafemoral joint
what is the acetabulum
cup-like concave socket
located on the lateral aspect of the pelvic bone
how is the acetabulum oriented
faces laterally and somewhat inferiorly and anteriorly
acetabular labrum functions
- deepens the socket
- increases the concavity b/c it is triangular shaped
- grasp the head of the femur to maintain contact with the acetabulum
the head of the femur is oriented
by the femoral neck
medially, superiorly and anteriorly
coxafemoral joint description
diarthrodial joint
ball and socket
3 degrees of freedom
what motions does the coxafemoral joint do
ABD/ADD
IR/ER
Flexion/Ext
ROM flexion
0-90 w/ knee extended
0-120 or 135 w/ knee flexed
ROM extension
0-10 or 30
probably closer to 0, anything beyond 10 may be anterior pelvic tilt or lumbar spine motion
ROM ABD
0-30 or 50
ROM ADD
0-10 or 30
ROM IR
0-30 or 45
ROM ER
0-45 or 60
mechanical axis of the femur
line drawn from center of the femoral head
–> passes though a point in b/w the femoral condyles
where is the mechanical axis
most of it is outside the bone
–> can cause bending of the femur
what is the mechanical axis of the femur also called
weight bearing axis
angles of the femur
created by the head and neck of the femur on the shaft
head-neck angle of inclination
angle of torsion
head-neck angle of inclination
occurs in the frontal plane
angle formed by the intersection of the femoral neck axis and the femoral shaft axis
what is a normal head-neck angle for adults
125
what is head-neck angle at birth
150
head-neck angle types
coxa vara
coxa valga
coxa vara
decrease in the head neck angle
femoral head is pointing down
coxa vara results in
increased joint congruency
increased moment arm for the ABD
leg length discrepancy
increased shear force
coxa vara –> increased joint congruency
femoral head facing more towards acetabulum
coxa vara –> increased moment arm for..
ABDs
need less force production to produce the same amount of torque
less compression on the joint
muscles dont have to work as hard
coxa vara –> leg length discrepancy
affected femur will be too short compared to the unaffected side
coxa vara –> increased shear force
on the femoral neck and head
increased risk of fx of the femoral neck
moves mechanical axis medially and more outside the bone
coxa valga
increase in the head neck angle
coxa valga results in
decreased joint congruity
decreased moment arm for ABD
leg length discrepancies
coxa valga –> decreased joint congruity
increased chance of dislocation
coxa valga –> decreased moment arm for…
ABDs
increased muscle force required to create the same amount of torque
increase compression on the joint
coxa valga –> leg length discrepancy
affected femur is too long
angle of torsion of the femur
twisting
occurs in the transverse plane b/w the femoral neck axis and the transcondylar axis
what is the angle of torsion referred to as
anteversion
anteversion in a normal adult
15 degrees
anteversion in an infant
up to 40
pathological increase in the angle of torsion
anteversion
beyond 15 degrees of anteversion
someone is considered to have an anteverted hip
femoral head is facing more anteriorly
–> toes medially rotate
–> toe is posture
what happens to IR with anteversion
there is more room to glide posteriorly
increased IR
what happens to ER anteversion
decrease in ER
–> little room to glide anteriorly
pathological decrease in the angle or torsion
retroversion
femoral head is facing too far posteriorly
–> toe out posture
anything less than 15 degrees is a retroverted hip
what is a retroverted hip d/t
w sitting
intrauterine “packaging”
what happens to ER –> retroversion
increases
more room to glide anteriorly
what happens to IR –> retroversion
decreases
less room to glide posteriorly
arthrokinematics –> open chain
convex femur moves on the concave acetabulum
BM + roll –> same
glide –> opposite
flexion and extension arthrokinematics
Flexion: BM + R –> A, G –> P
Extension: BM + R –> P, G –> A
ABD and ADD arthrokinematics
ABD: BM + R –> S, G –> I
ADD: BM + R –> I, G –> S
IR and ER arthrokinematics
IR: BM + R –> A, G –> P
ER: BM + R –> P, G –> A
arthrokinematics –> closed kinetic chain
pelvis moves on the femur
concave on convex –> everything same direction
motions of closed kinetic chain
anterior and posterior pelvic tilt
lateral pelvic tilt
pelvic rotation
anterior pelvic tilt
occurs in sagittal plane
relative hip flexion counteracted by the extenders
posterior pelvic tilt
occurs in sagittal plane
relative hip extension counteracted by the flexors
lateral pelvic tilt
occurs in the frontal plane around an A-P axis
hip hiking (iliac crest elevates)
hip drop (iliac crest drops)
hip hike
relative ABD
counteracted by ADDs
hip drop
relative ADD
counteracted by ABDs
pelvic rotation
transverse plane around a vertical axis
relative internal rotation
rip hip with left forward rotation
left hip with right forward rotation
relative external rotation
left backward rotation –> relative ER of right hip
right backward rotation –> relative ER of left hip
iliofemoral ligament
fan shaped ligament on the anterior aspect
“y shaped”
strongest ligament at the hip
where does the iliofemoral ligament run
AIIS to intertrochanteric line of the femur
when do all fibers of the iliofemoral ligament tighten
hip extension
when do the superior fibers of the iliofemoral ligament tighten
ADD
when do the inferior fibers of the iliofemoral ligament tighten
ABD
what ligaments form the Z ligament
iliofemoral and pubofemoral
primary role of ligament of the head of the femur
blood supply and nerve supply to the femoral head
when is the joint capsule the strongest
anterosuperiorly
wolff’s law
bone is laid down in a reaction to stress placed on the bone
zone of weakness
an area in the femoral neck
trabeculae are thin and do not cross each other
increased risk of fx
point of strength
all the systems intersect each other
