Lecture 5 (test 2): Hip Arthrology Flashcards
where is the femoral head located
just inferior to mid 1/3 of inguinal ligament
describe the femoral head
2/3 is nearly a perfect sphere
just posterior to center = the fovea
covered by articular cartilage except fovea
describe ligamentum teres
tubular
synovial lined connective tissue
houses acetabular artery
contains mechanoreceptors
runs from transverse acetabular ligament to fovea
describe the acetabulum of the hip
deep and cuplike socket
how deep is the acetabular notch
60-70 degree opening
describe the acetabular fossa floor
floor of fossa
no cartilage
no contact
filled with fat, blood vessels, synovial membrane, and ligament
where does the femoral head generally contact (describe this surface)
normally contacts along lunate surface
lunate surface is covered in articular cartilage and is thickest along the superior anterior region which is where there is the highest joint force when walking
describe the forces (%BW) generated at the acetabulum during swing and mid stance
13% at swing and 300% BW at midstance
what all occurs at the hip joint during midstance
notch widens
lunate deforms
increase contact area
decrease pressure
how much compression forces (% BW) occur during the stance and swing phases
stance = 0-60%
swing = 60-100%
how does the area of joint contact increase from swing to stance
increases from about 20% of the lunate surface during swing to 98% during mid stance
describe the hip labrum
string flexible ring of fibrocartilage rim of acetabulum
provides mechanical stability “grip” and deepens socket
mechanical seal keeps neg pressure, and fluid sealed to reduce friction/contact stress and lubrication
poor vascularization but well innervated
where does the transverse acetabular ligament span
the acetabular notch
the internal labrum blends with what to form what
blends with articular cartilage of acetabulum to form labro-chondral junction
how does hip joint project
laterally, inferior and anterior inclincation
what is dyplastic acetabulum
malformed and does not fully cover the femoral head
chronic dislocation/OA/pain
what measures define dyplastic acetabulum
center edge (CE)=degree acetabulum covers the femoral head
what is the acetabular anteversion angle
extent to which the femur faces anteriorly
NLs is 20 degrees
what is femoral version (ante/retro)
defined as the angular difference between axis of femoral neck and transcondylar axis of the knee (craig’s test)
what is acetabular anteversion
measurement used on a cross section imaging especially pelvic CT for the assessment of acetabular morphology
what is femoral torsion
relative RT between the bones shaft and neck
normal = 15 degrees
what is consdiered excessive anteversion or retroversion
ante = >15
retro = < 15
what is the femoral torsion of an infant
originally around 40 degrees anteversion
it derotates to about 15 degrees by 16 years old
excessive anteversion can cause what issues
dislocation
OA
increase contact stress
“in-toeing”
what ligaments reinforce the external capsule, iliocapsularis, gluteus min, and rectus femoris
iliofemoral
pubofemoral
ischiofemoral
describe the iliofemoral ligament
thick
strong upside down Y
medial and lateral
from AIIS to rim of acetabulum to the intertrochanteric line
elongated with full hip ext and full ER
when is the pubofemoral ligament taut
hip ABD
hip EXT
some in hip ER
describe the ischiofemoral ligament and when its taut
posterior
spirals
taught in IR and ABD
what is closed packed of the hip
greatest simultaneous stretch to many structures
full ext (20 deg) and slight IR and ABD
for hip this is NOT position of max congruency
what is the posiiton of max congruency for the hip
90 flexion and mod ABD/ER
femoral on pelvic bs pelvic on femoral
femoral on pelvic = femur moves around fixed pelvis
pelvic on femoral = RT of pelvis over fixed humerus
amount of femoral on pelvic hip flexion
120-140 deg
after this usually leads to post pelvic tilt + lumbar flexion
how much femoral on pelvic hip ext
18-30 deg
how much ABD/ADD occurs with femoral on pelvic movement
abd = 40-55 deg limited by pubofemoral and adductor muscles
add = 20-25 deg limited by abd, piriformis, and ITB
how much femoral on pelvic IR and ER are present
IR = 30-45
ER = 32-50
what is ipsidirectional lumbopelvic rhythm
lumbar spine and pelvis move in same direction
maximizes angular displacement of the entire trunk
what is contradirectional lumbopelvic rhythm
lumbar spine and pelvis move in opposite direction
supralumbar (above L1) can stay nearly stationary
used in walking where the head and eyes need to be still
L/S is a decoupler
describe the sagittal plane pelvic RT in contradirectional lumbopelvic rhythm
hip flexion/ant tilt/lumbar spine ext
describe the frontal plane pelvic RT in contradirectional lumbopelvic rhythm
ABD of support hip (standing)/opp iliac crest hikes/opposite side spine lateral flexion
add is opposite
describe the spine/pelvic movement with IR and ER of hip
IR = non support LE rotates fwd and spine twists opposite
ER = non support LE side rotates bwd and spine twists opposite
describe the arthrokinematics of NWB/open chain flexion and ext of hip
Flexion = rolls anterior and slides posterior/inferior
ext = rolls posterior and slide anterior superior
describe the arthrokinematics of IR and ER in open chain hip movements
IR = roll anterior and slide posterior
ER = roll posterior and slide anterior
describe the arthrokinematics of ABD and ADD in open chain hip movements
abd = roll superior, slide inferior
add = roll inferior, slide superior
