KNS Exam 2

the acetabulum articulation surface is

concave

Describe the orientation of the acetabulum relative to the pelvis.

lateral, inferior, anterior

an acetabulum that is too shallow

less congruency, less stability

an acetabulum that is too deep

more congruency, less ROM

What is a dysplastic acetabulum?

A malformed acetabulum that does not adequately cover the femoral head

Which of the following is not a potential consequence of a dysplastic acetabulum?

decreased stress

What is the orientation of the femoral head?

medially and slightly anterior

What is the function of the femoral neck?

— connects the femoral head to the shaft

— displaces the shaft away from the joint 

the femoral neck displacing the shaft away from the joint will

reduce the likelihood of impingement

What is the orientation of the femoral shaft?

slight anterior complexity

which of the following does not determine the shape and configuration of the femur?

strength of muscle activation

Bones respond to ______.

stress

What two specific angulations define the shape of the proximal femur?

— Angle of Inclination

— Torsional Angle.

How is the angle of inclination viewed?

It is viewed in the frontal plane

What is the angle of inclination?

the angle between the femoral neck and the femoral shaft.

What is the typical angle of inclination in at birth?

165-170

What is the typical angle of inclination in an adult?

125

What is coxa vara?

<125º

What are the positive effects of coxa vara?

– Increase moment arm of hip ABD

– increase stability (places femoral head more into acetabulum)

What are the negative effects of coxa vara?

— Increased torque (increasing fracture likelihood)

— decreased functional length = decrease force production

— shortened limb

What is coxa valga?

> 125º

coxa valga may be cause by

hip dysplasia

What are the positive effects of coxa valga?

– Decreased bending moment arm (less likely to fracture neck)

– Increased functional length = increases force production

What are the negative effects of coxa valga?

— Increased likelihood of dislocation/degenerative changes

— decreased moment arm for hip ABD

— lengthened leg

what is displayed by the image on the left?

coxa valga

what is displayed by the image in the middle?

excessive coxa valga

what is displayed by the image on the right?

coxa vara

What is femoral torsion?

The rotation between the femoral shaft and neck

What is femoral torsion viewed in? 

transverse plane

What is normal anteversion?

15º

What is excessive anteversion?

>15º 

What is retroversion?

<15º

How much anterversion do healthy infants have?

40º

With continued growth anterversion will derotate to ____ by age ___.

15; 16 

What gait pattern can excessive anteversion cause in children?

'In-toeing'

excessive anterversion is a result of 

excessive IR second to tightened muscles and ligaments 

excessive anteversion will typically resolve with time due to …

natural normalization of anteversion and compensation of the tibia

Which leg indicates an excessive anterversion?

the leg in the middle

Which leg indicates retroversion?

the leg on the right

the hip joint is designed for 

weight bearing (stability) and locomotion (moderate ROM)

What is the labrum?

fibrocartilage that assists with holding the head within the acetabulum

How does the hip joint compare to the shoulder joint in terms of stability?

deeper socket (acetabulum) and more stable bony structure,

making it more stable overall

What is the fovea on the femoral head?

a depression in femoral head

What structures are involved with the fovea? 

ligamentum teres attaches and acetabular artery enters

All of the femoral head is fully covered by articular cartilage except

fovea

the acetabulum is

deep hemispheric socket

the acetabular notch is

an inferior opening on acetabulum (60-70’ wide)

What is the lunate surface of the acetabulum?

horseshoe-shaped surface on acetabulum, covered with articular cartilage

During walk, the lunate is the region of the ______ joint force.

greatest

During gait, in midswing the body weight is

13%

During gait, in midstancee the body weight is

300%

Lunate surface ______ during midstance and acetabular notch ______. 

deforms, widens

When the Lunate surface deforms during midstance and acetabular notch widens, this will

increase contact area and decrease peak pressure

the labrum is

fibrocartilage encircling acetabulum

Which of the following is not true about the lubrum?

greatly vascularized/has a high ability to heal

The labrum is often involved in

– Degenerative osteoarthritis

– Acute trauma

– Developmental hip dysplasia

– Repeated femoral-acetabular impingement

What is the Center-Edge Angle of the acetabulum?

The degree to which the acetabulum covers the femoral head superiorly

The center-edge angle on average is

25-35º

A reduced center-edge angle

Increased risk of dislocation

Less contact area within joint

An increased center-edge angle

Increased chance of impingement

What is the Acetabular Anteversion Angle?

it’s the extent to which the acetabulum faces anteriorly

The Acetabular Anteversion Angle is typically 

20º

Acetabular Anteversion Angle leaves part of femoral head exposed so

anterior capsular ligament and iliopsoas tendon will cover

Excessive acetabular anterversion

Increases chance of dislocation

What is the open-packed position of the hip?

30 degrees flexion, 30 degrees abduction, and slight external rotation.

What is the closed-packed position of the hip where ligaments are taut?

Full extension, slight abduction, and slight internal rotation

What is the closed-packed position of the hip for congruent joint surfaces?

90 degrees flexion with ABD/ER

Open chain 

– Femoral-on-Pelvic Movements

– Movement of the femur on a relatively fixed pelvis

Close chain

– Pelvic-on-Femoral Movements

– Movement of the pelvis (and trunk) over fixed femur

Pelvic on Femoral - Hip FLX/EXT

anterior and posterior pelvic tilt

Pelvic on Femoral - Hip ABD/ADD

single limb stance

ABD: hiking on non-supported limb

ADD: hip drop on non-supported limb 

Pelvic on Femoral - Hip IR/ER

single limb stance

IR: adv of non-support side hip

ER: retraction of non-support side hip 

What are the primary hip flexor muscles?

Iliopsoas, sartorius, tensor fascia latae, rectus femoris, adductor longus, and pectineus.

What are the primary hip extensors muscles?

Gluteus Maximus, Hamstrings, Adductor magnus (hamstring head)

What are the primary hip abductor muscles?

Gluteus medius, gluteus minimus, and tensor fasciae latae.

What are the primary hip adductor muscles?

Pectineus, Adductor longus, Gracilis, Adductor brevis, Adductor magnus

Which muscles are responsible for external rotation of the hip?

Primary: Gluteus Maximus, Piriformis, Obturator internus, superior/inferior gemelli, quadratus femoris.

Secondary: Glutes medius/minimus (posterior fibers), Obturator externus, Sartorius, Biceps femoris (long head).

Which muscles are responsible for internal rotation of the hip?

Primary; None

Secondary: Gluteus medius and minimun (anterior fibers), Tensor fasciae latae, Adductor longus, Adductor brevis, Pectineus

Normal forces are approximately _____ BW across hip joint.

2.5 times

With a cane, forces are approximately _____ BW across hip joint.

1.5 times

With a weight, forces are approximately _____ BW across hip joint.

3.8 times

How does using a straight cane in the contralateral upper extremity affect hip joint forces?

— provides an abduction moment

— widens the base of support during stance,

— therefore, reduces the hip ABD moment required by the hip abductor muscles and decreases the overall forces

What bones comprise the pelvic girdle?

Sacrum, coccyx, and two hip bones (Os Coxae/innominate)

What are the three components of the Os Coxae?

Ilium, Ischium, and Pubis

What are the structures of the sacrum?

promontory, ala, auricular surface, formina

Why does the auricular structure shaped the way that it is?

for greater stability

What are the four joints of the pelvis?

sacroiliac (right/left), symphysis pubis, lumbosacral

What is not a component of the pelvic ring?

Unilateral sacroiliac joints (SIJ)

The pelvic ring transmit body weight ___________.

bidirectionally

Which structure is considered the keystone of the pelvic ring?

The sacrum

In an upright, neutral position of the pelvis should be

level (ASIS and pubic symphysis = same vertical plane)

Anterior Tilt

ASIS is ANTERIOR to pubic symphysis

Posterior Tilt

ASIS is POSTERIOR to pubic symphysis

lordosis

excessive inward curve of the spine

in an anterior tilt there is _____ lordosis, in a posterior tilt there is ______.

more; less

kyphosis

excessive outward curve of the spine

What is the optimal lumbosacral angle?

30º

What are the landmarks of the lumbosacral angle? 

A: point anterior to sacrum

A-B: line along base of sacrum

A-C: line parallel to floor 

as we increase the lumbosacral angle, we will ____ the ______ force.

increase; shear

the lumbosacral angle will _____ with anterior tilt, and _____ with posterior tilt.

increase; decrease