The Hip Joint Flashcards
function of hip joint
- support weight of HAT (head, arms, trunk)
- transmits force between pelvis & LE
type of joint (hip) & the degrees of freedom
- triaxial diarthrodial
- ball & socket
- 3 deg of freedom (flex/ext, IR/ER, abduct/adduct)
anatomy of the hip joint (what is on/around it)
- head & acetabulum
- loose capsule
- ligaments
- strong musculature
Anatomy of acetabulum
- covered with thick articular cartilage
- horseshoe shaped: superior articulating area
- fibrocartilage labrum: wedge shaped
trabecular lay down cells in the ________ due to ______
acetabulum; stress
b/c acetabulum is a weight bearing area!
Center edge angle aka angle of Wilberg
- angle between vertical & antero-lateral rim
- degree of inferior tilt
- most common joint for congenital dislocations
norm - 20-40 deg
Smaller center edge causes ________, leading to a ________ risk of __________
diminished head coverage, leading to an increased risk of superior dislocation
Center edge angle ________ with age, causing children to be ______ susceptible to dislocation
increases; more
Acetabular aversion “norms”
19 - 40 degrees
pathological issues of acetabular aversion causes:
decreased stability, ultimately causing anterior dislocation
Acetabulum - labrum
deepens socket, causing an increase in concavity
- grasps the head of femur
labrum: fibrocartilage wedge shape
Femoral head
- 2/3 of a sphere
- covered by articular cartilage
- fovea
fovea
ligament of head of the femur (ligamentum teres)
- carries neurovascular supply to head of femur
Femoral head - angle of inclination
frontal plane
congruency occurs at 125 deg in adults – decreases with age 150 –> 120 deg
COXA VALGA
femoral head angle of inclination
greater than 125 degrees
valgus at hip contributes to veras at knee
COXA VERA
less than 125 degrees
veras at hip contributes to valgus at knee
femoral head- angle of torsion
- transverse plane
- angle between femoral neck & condyles
averages 12-15 degrees in normal adults
anteversion
TOE IN
increase in torsion angle –> internal femoral torsion
retroversion
TOE OUT
decrease in torsion angle –> external femoral torsion
Hip joint congruence
- very congruent but not perfect b/c we need to weight bear and we need “cushion” to do so
- acetabulum does not cover head superiorly
- only periphery of acetabulum is articular
- deep acetabular fossa important for vacuum - sucks femoral head in the fossa
pathological angle of inclination/torsion causes:
less congruency, leading to instability
Change in center edge can alter ______ causing a ______ in stability
congruency; decrease
Hip joint capsule
- strong & dense –> important for stability
- attaches to periphery of acetabulum and blends with labrum
- covers femoral neck & attaches to base of neck
Iliofemoral ligament
ANTERIOR
- Y ligament of Bigelow
- AIIS to the intertrochanteric line
- checks hip extension
(check = prevents/resists)
Pubofemoral ligament
ANTERIOR
- pubic ramus to intertrochanteric fossa
- taut in abduction & extension
Ischiofemoral ligament
POSTERIOR
- femoral neck to acetabular rim/labrum
Ischiofemoral ligament horizontal fibers tighten during:
ABDUCTION
Ischiofemoral ligament spiral fibers tighten during _____ & loosen during ________
extension; flexion
Ischiofemoral ligament during close-packed position:
extension
ligament of head of femur
- Doesn’t play a major role in stability
- Neurovascular conduit (especially in young since vessels can’t cross cartilaginous endplates) == circumflex femoral artery
Weight bearing structures
- intricate trabeculae arrangement in femur & pelvis
- increase subchondral boned density in superior acetabulum primary weight bearing surface
Zone of weakness
- region of femoral neck
- susceptible to bending forces
- fracture 2 deg to increase forces or tissue changes (i.e. osteoporosis)
Arthrokinematics:
Neurtal flex/extend-
almost a pure spin
arthrokinematics:
outside of neutral-
combined spin & glide
arthrokinematics:
IR/ER & abduct/adduct-
spin & glide
arthrokinematics:
weight bearing femur fixed -
concave on convex (same direction)
Osteokinematics - normal flexion (ROM)
120 - 135 deg
Osteokinematics - normal extension ROM
10 - 30 deg
osteokinematics - normal abduction ROM
30 - 50 deg
Osteokinematics - normal adduction ROM
10 - 30 deg
Osteokinematics - normal ER ROM
45 - 60 deg
Osteokinematics - normal IR ROM
30 - 45 deg
Functional hip ROM - flexion
124 deg
tying a shoe or squatting
Functional hip ROM - extension
10 deg
gait
functional hip ROM - abduction
28 deg
squatting
functional hip ROM - ER
75 - 90 deg
foot across opposite thigh
HAT = ____ of total Body weight
2/3
each LE is _____ of total body weight
1/6
1/6 + 1/6 = 1/3
compression on the hip (due to grav) during a unilateral stance can be calculated by
(HAT + LE) x BW ex- let BW = 180 lbs (2/3 + 1/6) x 180 = 5/6 x 180 = 150 lbs
Maintaining static equilibrium
1st determine torque at hip due to gravity
- Moment arm from AOR to LOG = 4 inches
- Adduction torque = force x MA (perp distance)
= (5/6)(BW)(MA)
=150 x 4
= 600 in-lbs
hip _____ exert an equal counter torque to maintain equilibrium/balance
abductors
compensatory lean when experiencing hip pain occurs on which side???
towards the affected limb
- compression on hip joint remains the same due to gravity
compensatory lean: LOG moves ___to or from?___ hip joint AOR
towards!
- reduces the HAT moment arm
- reduces the total force put on hip so it feels less painful when you do a compensatory lean
Which hand to we put cane in
contralateral side
side opposite of injury
why do we give ppl walkers/canes
compensatory lean causes wear & tear
why do we put the cane on the opposite side of injury
so they gluteus minims & medius don’t have to do work…. cane pushes you back upright (w/ lat dorsi & arm)
- – muscles will have to generate less force to work
- promotes upright posture
what happens when you put the cane on the ipsilateral side????
muscles will need to work just as hard with the cane as without the cane
