Hip Flashcards
Acetabulum
Pubis: 25% of acetabulum anteriorly
Ischium and ilium together: 75% of acetabulum
- Ischium: posteriorly
- Ilium: superiorly
Incomplete rim inferiorly = acetabulum notch, spanned by transverse acetabular ligament
Opening allows us to have a lot of mobility as femoral head rolls/glides around acetabulum
Acetabular Dysplasia
Malformed acetabulum leads to lack of femoral head coverage
Acetabulum not formed properly - instability in joint (surfaces are not big enough)
Altered stresses b/c surface area is congruent or smaller surface area
Acetabular Alignment - Center Edge Angle
Describes orientation of the acetabulum
Fixed angle of acetabulum in frontal plane (orientation of acetabulum in frontal plane)
Measures from hip joint center to rim of acetabulum (measure how much acetabular rims covers femoral head)
Too little coverage - dysplastic hip (dislocate)
Too much coverage can cause pinching and discomfort as head rolls out into abduction (pinching b/w acetabulum and femoral neck)
Looking at superior edge of femoral head and how much coverage acetabulum is giving
<16 degrees - markedly reduced acetabular coverage-dysplasia, increased stress
16-25 - reduced acetabular coverage - possible dysplasia, increased stress
35-40 - normal
> 40 - too much coverage
Acetabular Alignment - Acetabular ante- and retro version
Transverse/horizontal plane
What direction acetabulum face
Anteversion
- Acetabulum faces too far anteriorly (dislocate hip anteriorly)
- Can lead to unstable hip
- Opening up joint
- Ball is going to pop out of socket anteriorly
Retro version
- Acetabulum faces too far posteriorly
- Can lead to over-coverage, impingement b/w acetabulum and femoral head, abnormal stresses
Position can’t be created
Normal - 20 degrees
Anteversion - more than 20 degrees
Retroversion - less than 20 degrees
Labrum
Fibrocartilaginous ring functions to deepened acetabulum b/c it’s not deep enough
Provides stability, but more mobility
Increases contact area
Decreases stress
Labral tears are known source of pain
- Poor vascularization
- Doesn’t head well
Angle of Inclination
Frontal plane angle b/w femoral neck and femoral shaft
Normally 125 degrees
Coxa valga and coxa vara
Coxa Valga
Pathological increase (angle of inclination is more than 125 degrees)
Vertical orientation - moment arm of hip abductors is smaller - less mechanically advantageous - need to work harder
Coxa Vara
Pathological decrease (angle of inclination is less than 125 degrees)
Put more pressure on neck - more bending moment
Suffer from neck fractures
Abductors can function better here - moment arm increases (greater force can be generated, less work needs to be done) - greater mechanical advantage
Angle of Torsion
Femoral torsion describes relative motion (twist) b/w shaft and neck
Line thru femoral neck, condyles, head
Normally, 15 degrees anterior to frontal plane
Independent of acetabulum - occur on femur
Position of neck relative to femur
Excessive Anteversion
Angle of torsion
Increase in torsion - femur sits anteriorly
Less congruency b/w jt surfaces
Neck is more anterior to line from trochanter through femoral head
Individuals turn toes in, so that femoral head can IR and roll backward to increase joint congruency in acetabulum
Can be caused by W sitting in kids
Walk pigeon toes and can’t ER
More than 15 degrees
Retroversion
Angle of torsion
Line projects closely to frontal plane
Less than 15 degrees
Proximal Femur Internal Structure
Large bending moments at femoral neck
Bending moments reinforced by thick cortical bone/organized arrays of cancellous/trabecular bone
Cancellous bone extends from shaft to neck and head in organized arrays
Thick compact bone in cortex of lower femoral neck and in shaft
Capsule
Contributes substantially to stability
Thickened anteriorly/superiorly, thin posteriorly/inferiorly
Femoral neck - intracapsular
Greater/lesser troch - extracapsular
Synovial membrane
Mostly oriented parallel from neck to femur
Blood supply occurs here at the attachment of capsule to bone – vessels carrying blood to femoral neck and head
More likely to get femoral neck fractures b/c there is not a good blood supply to that region (just vessels to that area)
Hip is more likely to dislocate posteriorly b/c capsule is thinner
Ligaments
Reinforce capsule
Limites extreme motion
Iliofemoral, pubofemoral, ischiofemoral
End ROM of hip – defined by ligaments, capsules, muscles
Iliofemoral Ligament
Y ligament
Resists hip extension
Fan shaped, resembles inverted Y
Anterior
Provides stability when hip is extending (femoral head goes anterior)
Pubofemoral Ligament
Anterior
Ischiofemoral Ligament
Posterior
Hip Joint Stability
Achieved due to:
- Bony configuration
- Strong capsule
- Reinforcing ligaments
Most congruent position - 90 degrees hip flex, slight abduction, ER
Close-Packed Position
Full ext, slight IR, abduction
Elongates most of capsule, not the most congruent
Most taut
Open-Packed Position
30 degrees of hip flex, slight abduction, ER
Most space in capsule
Feeling good for patient who is swollen/edema (room for fluid to move)
Can shorten hip flexors and cause contracture
Hip Joint Mobility - Osteokinematics
Mostly osteokinematic motion
Some arthrokinematic motion (translation present)
Relative alignment of acetabulum and femoral head dictates available motion of hip
Normal: head of femur oriented anteriorly and superiorly in the acetabulum, exposes anterior femoral head and leaving large articular surface available for flexion, limits maximal extension
Glides
Used as intervention to improve osteokinematic motion
Lack hip flexion - posterior glide
Lack hip extension - anterior glide
Femur on Pelvis Osteokinematics
Ball and socket joint
Hip flex/ext - M/L AoR - sagittal plane
Abd/add - A/P AoR - frontal plane
IR/ER - vertical AoR - transverse plane
Pelvis on Femur Osteokinematics
Anterior and posterior pelvic tilt (flexes/extends hip) - sagittal plane - M/L AoR
Lateral pelvic tilt (abd/add hip) - frontal plane - A/P AoR - restricted to about 30 degrees
Pelvic rotation (IR/ER hip) - transverse plane - vertical AoR
Anterior and Posterior Pelvic Tilt
Anterior - hip flexion
Posterior - hip extension
Vertical line will intersect ASIS and public symphysis
Lateral Pelvic Tilt
Hip hike - stance leg is abducting
Hip drop - stance leg is adducting
Pelvic Rotation
Pelvis moving, stationary leg
Rotate pelvis toward stationary leg - stationary leg toes in - IR
Rotate pelvis away from stationary leg - stationary leg toes out - ER
Interaction of Hip and L/S Motion
May explain differences in normal hip ROM (femur-on-pelvis)
Posterior pelvic tilt can contribute to hip flexion (move into flexion - reach hip end ROM - continue to push - pelvis tilt posteriorly - lumbar flexes, pelvis rotates - augments hip flexion)
Anterior pelvic tilt contributes to apparent ext (move into ext - continue to push - pelvis tilts anteriorly - lumbar ext - augments hip ext)
Trunk sidebend and frontal plane pelvic motion contributes to apparent abduction
When we walk, long stride length - combo of pelvic rotation and lumbar rotation - gives hip ext
Lumbopelvic Rhythm
Pelvic motion on femur affects lumbar spine motion and vice versa - due to distal spine attachment to pelvis
Ipsilateral and contralateral
Ipsidirectional Lumbopelvic Rhythm
Flex forward - take slack of each vertebrate until end ROM - continue to bend - pull of lumbar spine causes pull of sacrum - causes ipsidirectional anterior rotation of pelvis
Contralateral Lumbopelvic Rhythm
Keeps head above trunk when standing
Anteriorly tilt pelvic – opposite direction motion (pelvis rotates anteriorly, lumbar spine extending)
Keep us upright
Arthrokinematic (Convex-Concave) Rules
If convex joint surface moves on concave surface, roll and glide occur in OPPOSITE directions
If concave joint surface moves on convex surface, roll and glide occur in the SAME direction
Femoral head will glide within the acetabulum in a direction OPPOSITE the motion of the distal femur
Roll - direction of distal femur
-Ext: femur back, head rolls back, head glides anterior
Arthrokinematics (Spin)
Hip flexion/extension mostly spin
-Posterior in flexion, anterior in extension
Hip flex/ext combined with abd/add or IR/ER- both spinning and gliding
Closed chain motion= concave on convex
- Flexion (Pelvis moving anteriorly on femur): anterior glide, anterior roll
- Extension: posterior glide, posterior roll
Double Limb Stance
Hips in neutral, weight is distributed evenly
LOG is just posterior to the M/L AoR for flex/ext
Body weight is transmitted thru the SIJ to femoral heads
If in alignment, no muscular force is needed
Glux max is not contracted - when you move, the LOG moves anterior, which causes it to fire
Standing normal - muscles are quiet
Capsules, ligaments, tendons keep us upright
Single Limb Stance
One hip joints carries full body weight
Weight of NWB leg is hanging
BW causes compression as well as torque - compression at hip, adduction torque as gravity works to drop pelvis
Requires counter torque or pelvis will drop (abductors)
Standing on one leg - add rotational torque (gluts fire to keep me stabilized on one leg)
Single Limb Stance - What if Abductors Can’t Generate Enough Torque?
Lateral trunk lean
- Toward the side of weakness/pain
- Brings LOG closer to hip joint AoR
Trendelenberg
-Contralateral pelvic drop (NWB pelvis drops) w/ or w/o lateral lean
Contralateral cane
- Provides counter torque to assist abductors
- Reduces compressive forces by decreasing force generation from abductors
Trendelenberg
Gluts not strong
Opposite pelvis drop
Shift trunk over leg to compensate for weak gluts
Shift body, so that trunk is lateral to AoR
AoR is ant/post, but body shifts lateral to this line
Hip Flexors
Iliopsoas, sartorius, TFL, rectus femoris, adductor longus and pectineus
Pelvic-on-femur hip flex - anterior pelvic tilt (force couple = iliopsoas and erector spinae)
Femur-on-pelvis hip flex - demands abdominal muscles to stabilise L/S when hip flexion is performed w/ knee ext (SLR) - would result in lumbar ext if abs did not stabilize spine
Hip Extensors
Glut max, hamstrings, adductor magnus
Pelvic-on-femur hip ext
- Posterior pelvic tilt (force couple = hamstrings and abs)
- Control trunk in forward lean (tilt body forward - glut max is helping to stabilize hip, so we don’t fall into flexion)
Femur-on-pelvis hip ext
- Flexed position favors increased extensor torque generation from glut max, adductors, hamstrings (able t do more mvt)
- Glut max is quiet is standing (b/c HAT weight extends hip)
- Glut max activity in single limb squat, mini squat, ascending stairs
- Glut max and hamstrings active during terminal swing and beginning of stance (eccentric contraction)
Hip Adductors
Pectineus, gracilis, adductor longus, adductor brevis, adductor magnus
Produces torques in multiple planes
- Frontal: pelvic-on-femur, femur-on-pelvis
- Sagittal: act as either flexors or extensors, depending on position of hip
Important role in stabilizing pelvis during weight shifting from one limb to another
Position of flex - adductors in posterior position of M/L AoR to assist w/ hip ext
Position of ext - adductors anterior to M/L AoR will help with flex
Hip Abductors
Glut med, glut min, TFL
Essential during gait
- Control of single limb stance (pelvis on femur)
- Responsible for producing force 2X BW during gait
- Produce greatest torque in slight add/neutral position
- Least torque in fully shortened position (test muscles in this position b/c pts generate least force)
Internal Rotators
Glut med, glut min, TFL, adductor longus/brevis, medial hamstrings
Greatest torque when hip is flexed to 90 degrees b/c it moves the LOA perpendicular to AoR (MMT in this position)
Visible functionally in stance phase of gait (pelvis comes forward)
No prime muscle that does IR - fibers of other muscle that works to IR
External Rotators
Glut max, sartorius, piriformis, gemelli, obturator internus, quadratus femoris
Most evident during pelvic-on-femur rotation (planting and cutting maneuver)
LOA oriented toward horizontal plane
Piriformis - changes functions from ER to IR after 90 degrees b/w line of pull is changed to anterior AoR
Special Tests
Part of examination
Selected specific to joint/structure
- “Provocative in nature”
- Confirms suspected diagnosis
- Assists w/ differential diagnosis
- Differentiates b/w structures
Always test uninvolved side first - baseline comparison
Ely’s Test
Purpose: to test for rec fem tightness
Procedure: patient prone, PT brings foot to butt while stabilizing pelvis and checking for anterior pelvic tilt
Positive: anterior pelvic tilt/ipsilateral hip flex spontaneously occurs
Negative: no pelvic mvt, heel touches or approximates butt
FABER Test (Flex, Abd, ER)
Purpose: to test for iliopsoas spasm or SI joint intervention
Procedure: patient supine, PT passively flexes knee, places foot on knee of opposite leg (Figure 4), PT slowly drops knee
Positive: knee doesn’t drop below level of opposite thigh
Negative: knee lowers to level of table or level of opposite thigh
Ober Test
Purpose: to screen for IT band contracture
Procedure: pt sidelying w/ bottom hip/knee flexed, PT stabilizes pelvis and passively abducts and extends top hip, and then slowly lowers legs
Positive: test thigh doesn’t lower past horizontal (remains abducted)
Negative: test thigh lowers into hip add
Thomas Test
Purpose: to screen for hip flexor contracture
Procedure: pt supine w/ knee flexed to chest, PT assess straight leg for position relative to table
Positive: straight leg will raise off exam table (muscle stretch may be felt)
Negative: straight leg rests on exam table
Often performed w/ patient at edge of table, allowing hip to extend, knee to flex and providing PT w/ additional info regarding rec fem (extended knee - rec fem causing hip contracture)
Trendelenberg
Purpose: to screen for hip stability/hip abd weakness
Procedure: pt standing, stand on unaffected first, then stand on affected side while PT watches contralateral pelvic drop
Positive: Contralateral pelvic drops when standing on affected leg suggesting markedly weak gluteus medius or an unstable hip
Negative: Contralateral pelvic rises or stays level
Weber-Barstow Manuever
Purpose: to screen for limb length asymmetry
Procedure: pt supine w/ hips and knees flexed, find medial malleoli and go distal, pt bridges, PT extends legs and reassesses symmetry
Positive: asymmetrical position of medial malleoli
Negative: symmetrical position of medial malleoli
