hip part 2 Flashcards
what makes up the structure of the acetabulum?
fusion of the following 3 bones:
pubis 1/5
ischium 2/5
ilium 2/5
how long does it take for full ossification of the acetabulum and why is it important?
15-25 years
important bc if lateral fall in younger growing years theres a weakened acetabulum bc not fully developed
what is the structure of the acetabulum?
horseshoe shaped articular area
fibrocartilagenous labrum (thick which contributes to strength of the joint)
transverse acetabular ligament ( spans articular gap, forms roof of tunnel)
what is the spatial orientation of the acetabulum?
faces laterally, anteriorly, and inferiorly
for males and females what is the normal anterior location of the acetabular?
18.5º males
21.5º females
for males and females what is the normal inferior location of the acetabular?
22º-42º range
average 38º males
average 35º females
what makes up the center edge angle?
center point of the head of the femur
vertical (longitudinal) reference line up
final line drawn to most lateral aspect of the osseous part of the acetabulum
what happens to the center edge angle with age?
it increases with age because of wolffs law boney spurs and osseous growths increases the osseous part of the acetabulum increasing the angle
what are the 3 ways the acetabular changes with aging and the benefit or problem with each?
ossification of the articulation of the three bones of the pelvis- increased “central stability”
decreased acetabular “roundness”- reduced co-aption (lose ROM)
increased center edge angle- increased superior stability
what is the structure of the proximal femur?
more spherical than acetabulum
fovea capitis- could be torn with artery if dislocated which leads to necrosis of femoral head
what is the spatial orientation of the proximal femur?
projects medial, superior and anterior
what is important of the acetabulum and femur spatial orientation?
both the acetabulum and femur head are anterior so doesn’t line up which creates increased mobility. The other 2/3 components line up which increase stability
what is the angle of inclination?
the frontal plane angulation between the shaft and neck of femur
what does the angle of inclination contribute to?
the normal valgus position of the knee
what happens to the angle of inclination over time?
decreases with age
150º early infancy
125º in adults
120º in elderly
why does the angle of inclination decrease with time?
due to the bending moment at the femoral neck due to constant pull of gravity
what is coxa valga?
increase angle
increase leg length produces hip adduction
increase “pre-load” to hip abductors
decrease moment arm of abductors
what could coxa valga or greater leg length lead to over time?
joints above and below would have to side bend opposite direction to compensate
what is coxa vera?
decrease angle
decrease leg length
relative hip abduction
poor hip abductor length tension relationship
impingement may limit abduction ROM
stress concentration superior contact area
what could coxa vara or decreased leg length lead to over time?
force capability will be compensated so decreased torque of glute med and TFL
can lead to DJD (hip OA)
T/F: coxa vara can be congenital, developmental or traumatic
true
what are some positives of coxa vara?
increased moment arm for hip abductor force
alignment may improve joint stability
what are some negatives of coxa cara?
increased bending moment arm increases bending moment; increases shear force across femoral neck
decreased functional length of hip abductor muscles
what are some positives of coxa valga?
decreased bending moment arm decreases bending moment; decreases shear force across femoral neck
increased function length of hip abductor muscle
what are some negatives of coxa valga?
decreased moment arm for hip abductor force
alignment may favor joint dislocation
what is the angle of version?
transverse plane orientation of proximal neck of femur
runs through greater trochanter and neck of femur and use frontal plane reference line through lateral and medial femoral condyle
what creates angle of version?
en utero, lot of torsion twisting of femur creates normal angle of version
what is the normal angle of torsion/version?
8-15º is normal
what is excessive anteversion or medial femoral torsion?
> 15º
if uncompensated anteversion will expose significant amount of femoral head anteriorly= susceptible to dislocation
what is the compensated position for excessive anteversion?
lower extremity internal rotation “toed in”
what is retroversion or lateral femoral torsion?
< 8º
if uncompensated may expose head of femur posteriorly
what is the compensated position for vetroversion?
lower extremity may externally rotate and appear “toed out”
what position of the hip gives the greatest congruency and what is this position used for?
flexion, abduction and lateral rotation
used for posterior hip dislocation immobilization
why is it that flexion, abduction and lateral rotation is not the closed pack position of the hip joint if there is the greatest congruency?
because the capsular ligamentous structures are at their loosest
what is the open pack of the hip joint?
flexion, lateral rotation and abduction because the ligaments are “uncoiled” and loose
what is the closed pack position of the hip joint?
extension, internal rotation becuase the ligaments are taut
describe the stability of frontal plane spatial orientation of the hip
inferior angulation of acetabulum < the superior angulation of the femoral neck
therefore, a significant portion of the head remains uncovered which may lead to decreased superior stability because smaller center edge angle
describe the stability of transverse plane spatial orientation of the hip
the femoral neck and acetabulum are both directed anteriorly
thus, a significant portion of the anterior head is exposed which may contribute to reduced anterior stability= susceptible to anterior dislocation
where is the psoas major attached to?
anterior lumbar vertebra
if the psoas major is tight what would we see?
increase lumbar lordosis (pulls the vertebrae forward)
where is the iliacus attached to?
iliac fossa
if the iliacus is tight what would we see?
increase anterior pelvic tilt
what does iliopsoas do?
like the bicep of the hip, its a prime flexor, and external rotator
what does tensor fascia lata do?
flexes and internally rotates hip
abducts the hip if already flexed
what is the most important contribution of TFL?
to maintain tension in the ITB
the ITB is considered to assist in relieving the femur of some of the tensile loads on the shaft, how does the TFL contribute?
it has a roll in “taking up the slack” int he ITB to enhance this function
what are the 3 parts of the gluteus medius?
like the deltoid of the hip
anterior, middle, and posterior
what are the actions of the gluteus medius?
all fibers abduct
anterior fibers flex and IR
posterior fibers extend and ER
why is the attachment of the adductors to the pubic ramus clinically significant?
in the presence of adaptive shortening of adduction= downslip of hemipelvis
what is the only adductor to cross the knee?
gracilis
which muscles primarily medial rotate (internally) the hip?
none
which muscles can contribute to medial hip rotation?
muscles with lines of pull anterior to the hip joint axis at some point of the ROM may contribute
TFL and anterior glute prob the most significant
also glute min, piriformis if hip >90 flexed
what are the primary 6 lateral hip rotators?
obturator internus
obturator externus
gemellus superior
gemellus inferior
quadratus femoris
pirifromis
what are the secondary lateral hip rotators?
posterior gluteus medius
superior gluteus maximus
if the hip is <90º flexed what does the piriformis do?
ER
if the hip is >90º flexed what does the piriformis do?
IR
