Kinesiology of the hip and pelvis

What three bones make up the acetabulum?

Ilium, ischium, pubis

Which axis connects center of hip joint to center of knee joint?

Mechanical axis

Which axis runs along shaft of femur (and is more lateral)?

Anatomical axis

Which part of the pelvis is a lot of your weight dissipated into?

Pubic symphasis

How many degrees is the angle of inclination at birth?

165-170

How many degrees is the angle of inclination in adults?

~125

Angle of inclination < 125 degrees is called

Coxa vara

Angle of inclination > 125 degrees is called

coxa valga

Advantage of coxa vara

longer moment arm so less force needing to be generated with the hip abductors therefore less JRF

Disadvantage of having coxa valga

Shorter moment arm so hip abductors have to generate a lot of/large force which increases JRF (+ increased risk of dislocation)

Disadvantage of coxa vara

increased shear force at neck of femur

Less than 15 degrees of femoral torsion with limited IR (+posterior femoral head positioning) and possible "toe out" walking

Excessive retroversion

when you stand on one leg and you shift the weight onto it, you likely fall into hip ____ ? (abd or add)

Adduction

Which hip joint structure is believed to be stretched with a combination of flexion, adduction, and external rotation & provides stability in the hip joint, especially with hip dysplasia?

Ligamentum teres

What hip joint structure adds stability to the femoral head by deepening the socket by ~30% creating a suction force and dissipating load?

Acetabular Labrum

What does a center edge angle of >40 degrees indicate?

Pincer

What does a center edge angle of

Dysplasia

Iliofemoral "Y ligament" prevents excessive ______ and ________

Extension and External rotation

Pubofemoral ligament restricts/prevents excessive _________, __________, and _______

Abduction, extension, ER

Ischiofemoral ligament restricts/prevents excessive ______ and ______________

IR and Extension

What 3 positions cause the hip capsular ligaments to be taut?

Extension, abduction and IR

What is the loose packed position for the hip?

some flexion, abduction, and slight ER

What is the close packed position for the hip?

full extension, slight abduction, slight IR

What is the arthrokinematic of femur on pelvis open chain hip flexion?

Anterior roll, posterior slide (also called superior roll, inferior slide)

What is the arthrokinematic of femur on pelvis open chain hip extension?

Posterior roll, anterior slide (also called inferior roll, superior slide)

What is the arthrokinematic of femur on pelvis open chain hip abduction?

Superior roll, inferior slide

What is the arthrokinematic of femur on pelvis open chain hip adduction?

Inferior roll, superior slide

What is the arthrokinematic of femur on pelvis open chain hip internal rotation?

Anterior roll, posterior slide

What is the arthrokinematic of femur on pelvis open chain hip external rotation?

Posterior roll, anterior slide

What is the arthrokinematic of pelvis on femur closed chain hip flexion (ant pelvic tilt)?

anterior roll, anterior slide

What is the arthrokinematic of pelvis on femur closed chain hip extension?

posterior roll, posterior slide

What is the arthrokinematic of pelvis on femur closed chain abduction?

Superior roll, superior slide

What is the arthrokinematic of pelvis on femur closed chain adduction?

Inferior roll, inferior slide

What is the arthrokinematic of pelvis on femur closed chain internal rotation?

Anterior roll, anterior slide

What is the arthrokinematic of pelvis on femur closed chain external rotation?

posterior roll, posterior slide

Cantilever bending is when there is ___________ in the superior femoral neck and __________ in the inferior femoral neck (compression or tension)

tension;compression

What hip muscles primarily extend the hip in the sagittal plane?

gluteus maximus, biceps femoris (LH), hamstrings, and adductor magnus (post head)

What hip muscles primarily flex the hip in the sagittal plane?

iliopsoas, sartorius, tensor fascia latae, rectus femoris, adductor longus, and pectineus

muscles posterior to the axis of rotation on the femur are ___________; muscles anterior to the axis of rotation on the femur are ____________ (flexors or extensors)

extensors;flexors

In anterior pelvic tilt, the iliopsoas is ________ and the erector spinae are ________ (lengthened or shortened)

lengthened;shortened

Posterior pelvic tilt occurs due to what two muscles acting as a force-couple?

hip extensors- shortened & spinal flexors (lumbar)- shortened

Anterior pelvic tilt occurs due to what two muscles acting as a force-couple?

hip flexors- shortened & spinal extensors (lumbar)- shortened

To control a forward lean/bend, what muscles would need to be strengthened?

Hip extensors: Hamstrings and gluteus maximus

What hip muscles primarily adduct the hip in the frontal plane?

Primary: pectineus, adductor longus, gracilis, adductor brevis, adductor magnus

Secondary: biceps femoris (LH), gluteus maximus (inferior fibers), quadratus femoris, obturator externus

What hip muscles primarily abduct the hip in the frontal plane?

Primary: gluteus medius, gluteus minimus, TFL

Secondary: gluteus maximus

What muscle can extend the hip when its in hip flexion and flex the hip when its in hip extension

Adductor longus

Which muscle group is capable of IR and/or ER?

Abductors

What muscles are responsible for internally rotating the hip in the transverse plane?

Primary: none

Secondary: gluteus maximus, TFL, adductor longus, adductor brevis, pectineus

Why are IR muscles able to be much more effective at producing IR torque when the hip is flexed to 90 degrees?

Hip flexion increases transversely oriented component of IR muscles

Adductor muscles are almost perpendicular to S/I axis with hip at 90 degrees flexion

What muscles are responsible for externally rotating the hip in the transverse plane?

Primary: gluteus maximus, PGOGOQ

Secondary: gluteus medius & minimus, obturator externus, sartorius, biceps femoris (LH), and iliopsoas if hip is ABD

Joint reaction force is the sum of what two components?

External force (EF) and internal force (IF)

Where in the hip joint is the articular surface of the femoral head and acetabulum the thickest?

Superiorly

Forces are approximately ____ x _____ across hip joint

2.5-3 x BW

Which side should you have someone use a cane if they have a right hip injury?

Left side

What side should you recommend carrying heavier objects on if someone has a right hip injury?

Right side

Lateral trunk bending means that the ipsilateral hip has minimal activation of what muscle group? How does this affect the JRF of the ipsilateral hip?

Abductors; JRF will increase

Is the iliofemoral ligament stretched or tight in a posterior pelvic tilt?

Stretched

What muscles are working eccentrically and what muscles are working concentrically to perform a soccer ball kick with the right leg? (left leg is stabilizing on floor)

Eccentric: left glute med

Concentric: right adductors + pectineus

When the piriformis muscle is positioned inferior to the hip joint axis, what muscle actions can it perform? What about when the hip is flexed to 90 degrees causing it to move superior to the axis?

Abductor and ER; IR