Hip Biomechanics

Femoral neck must withstand large _________ loads at superior aspect and large ____________ loads at inferior aspect.

tensile, compressive

Subchondral bone of acetabulum is thickest where?

weight is being transferred

Acetabulum faces which three directions?

anterior, lateral, inferior

The neck of the femur and the shaft of the femur form a 125 degree angle. This is referred to as the

angle of inclination

In single leg stance, JRF are how many times the body weight? 66% of the JRF is from which muscle?

2.5-3x
hip abductor muscle force

Increase compressive force at the femoral neck. Decreased distance between hip joint and greater trochanter. Decreased contact area and contact area moves more laterally? What about the glute Med?

Coxa Valga
(glute med becomes actively insufficient, shorter moment arm)

Increased bending moment at the femoral neck. Increased distance between hip joint and greater trochanter. More medial force. Glute med?

Coxa Vera
(glute med will have better force generating capacity. More tensile force, longer moment arm)

What are the degree ranges for normal ante version at the hip?

8-15 degrees

Excessive ante version degree range? What will we see with hip and toe?

35 degrees; medially rotated

Retroversion degree range? What will the hip do?

less than 8 degrees; hip laterally rotates

Acetabulum articular surface is covered in hyaline cartilage. What do we call this? Where does this run from?

lunate surface
7-4 o'clock

What provides vascularity to head and shaft of femur?

ligamentum teres

What piece of periarticular connective tissue improves bony congruency and deepen the hip socket?

labrum

What does the iliofemoral ligament limit?

excessive extension and lateral rotation

What does the ischiofemoral ligament limit?

excessive extension, medial rotation, and abduction

What does the pubofemoral ligament limit?

excessive extension and abduction

What is the capsular pattern of the hip for Loss of IR?

flexion (most limited) > abduction > extension

What motion puts the most amount of tension on the ilio, ischio, and pubofemoral ligaments? What one motion could put them on slack?

extension; flexion

Arthros of hip flexion/extension in sagittal plane?

F: anterior roll, posterior slide
E: posterior roll, anterior slide

Hip arthros of abduction and adduction in frontal plane?

AB: lateral roll, medial slide
ADD: medial roll, lateral slide

Hip arthros for ER and IR in horizontal plane?

ER: posterior roll, anterior slide
IR: anterior roll, posterior slide

In standing, LOG from weight falls just posterior to hip joint AOR. What type of moment does this produce at hip? What structures prevent weight go body causing excessive movement at hip?

extension,
ilio, ischio, pubofemoral

If LOG shifts anterior to hip AOR, what type of moment is formed? What structures prevent body weight from causing excessive movement at hip?

flexion
glute max, adductors, hamstrings

Muscles contribute to posterior pelvic tilt if the lumbar flexors are also active? The more hip flexion, the more torque-generating capacity of the extensors.

hip extensors

Iliac and psoas major have an ER moment when in

hip flexion

If there is no movement at the pelvis when the hip flexors contract, what do we expect to see? If movement is allowed at pelvis when the hip flexors contract, what do we expect to see?

can flex
less flexion (anterior pelvic tilt and lumbar extension)

Iliacus and psoas contract. What do we see with lumbar, hip, and pelvic tilt?

lumbar extension
hip flexion
anterior tilt

If you are going up a steep hill, greatest activation will be in what muscles?

adductor magnus and semitendinosus

Piriformis, in hip flexion is a what? Neutral?

IR
ER

When the hip is flexed, glutes will be an

internal rotator

CKC: concave on convex pelvis on femur arthros.
Flexion: anterior tilt
Extension (posterior tilt)
Hip abduction (l hip abduction)

anterior roll and slide
posterior roll and slide
tilt and slide to left

CKC: concave on convex pelvis on femur arthros.
Hip adduction L hip adduction
Hip ER (R)
Hip IR (R)

tilt and slide to right
roll and slide posterior
roll and slide anterior