Structure and Motion of the Hip PT 706

what populations have disease and injury in hip joint?

old and young

where does pelvis transmit weight?

standing: down the legs

sitting: ischial tuberosity

pubic symphysis

cartilaginous joint at which two pubic bones fuse together

sacroiliac joint

synovial in childhood, but changes to synarthrosis as we age (little movement)

sacroiliac joint surface

As you age, your sacrum becomes more rigid and less smooth, used to give the age of a specimen at death

angle of inclination

angle in frontal plane formed between the longitudinal axis of the femoral head/neck and the longitudinal axis of the femoral shaft

angle of inclination adult norms

125 degrees

angle of inclination child norm

150 degrees

coxa varus

angle of inclination is less than 125 degrees

coza valgus

angle of inclination is more than 150 degrees

femoral torsion

Transverse plane, rotation between the bones shaft and neck

Head and neck are rotated anteriorly (normal)

normal femoral torsion in adults

10-20 degrees

normal femoral torsion in children

40 degrees

excessive anteversion

more than 20 degrees of femoral torsion

excessive retroversion

less than 10 degrees of femoral torsion

Forces from HAT (head, arm and trunk) and GRF (ground reaction force) contribute to what?

tensile forces on superior femoral neck and compressive forces on inferior femoral neck

What resists the tensile and compressive forces from HAT and GRF?

trabecular systems of bone

trabeculae

calcified plates of tissue within the cancellous bone

Adapt to stress requirements

what dictates formation of trabeculae?

mechanical stresses and structural adaptation to forces through the hip (bone forms based on the loads you apply, different parts of bone will look different depending on forces)

Wards Triangle

zone of weakness in femoral neck, no crossing of trabeculae, more potential for failure, fractures and osteoporosis

iliofemoral ligament

anterior hip ligament (y shaped)

pubofemoral ligament

inferior hip ligament

ischiofemoral ligament

posterior hip ligament

ligamentum teres

intra-articular, extrasynovial

Not a significant stabilizer, acts as conduit for secondary blood supply to head of femur

congruency during normal standing

femoral head is exposed anteriorly and slightly superiorly during normal standing

most bony congruency of hip

quadruped, femoral flexion, abduction and slight external rotation

ligamentous close packed position of hip

internal rotation with extension, some abduction

* different than the most bony congruent position of the hip

open packed (resting) position of hip

30 degrees of fexion, 20 dgerees of abduction and external rotation

(lying with pillow under knees)

hip flexion normal ROM

120 degrees

hip extension normal ROM

20 degrees

hip abduction normal ROM

40 degrees

hip adduction normal ROM

20 degrees

hip IR normal ROM

45 degrees

hip ER normal ROM

45 degrees

open chain arthrokinematics

hip flexion

Roll: anterior/superior

Glide: posterior/inferior

open chain arthrokinematics

hip extension

Roll: posterior

glide: anterior

open chain arthrokinematics

hip abduction

roll: superior

glide: inferior

open chain arthrokinematics

hip adduction

roll: inferior

glide: superior

open chain arthrokinematics

hip IR

roll: anterior

glide: posterior

open chain arthrokinematics

hip ER

roll: posterior

glide: anterior

closed chain arthrokinematics

hip flexion

roll: anterior

glide: anterior

closed chain arthrokinematics

hip extension

roll: posterior

glide: posterior

closed chain arthrokinematics

hip abduction

roll: superior

glide: superior

closed chain arthrokinematics

hip adduction

roll: inferior

glide: inferior

closed chain arthrokinematics

hip IR

roll: anterior

glide: anterior

closed chain arthrokinematics

hip ER

roll: posterior

glide: posterior

closed kinematic chain

anterior tilt of pelvis closed kinematic chain leads to what hip movement

flexion

closed kinematic chain

posterior tilt of pelvis closed kinematic chain leads to what hip movement

extension

closed kinematic chain

pelvic drop on non weight bearing side will cause

adduction of weight bearing hip

closed kinematic chain

pelvis hike on non weight bearing side will cause

abduction of weight bearing side

closed kinematic chain

forward rotation of pelvis on non weight bearing side causes

IR of hip of stance side

closed kinematic chain

backward rotation of pelvis on NWB side causes

ER of hip on stance side

primary flexors of hip

iliopsoas, sartorius, TFL, rectus femoris, adductor longus, pectineus

muscle force couple

two or more muscles simultaneously produce forces in different linear directions, although the resulting torques act in the same rotary direction

what muscle force couple produces anterior tilt of the pelvis

hip flexors and erector spinae work together in a rotary motion in the same direction

what must contract to keep the pelvis stable, and not tilt anteriorly due to hip flexor tendency

lower abs

primary hip extensors

gluteus maximus, hamstrings, adductor magnus

primary adductors

pectineus, adductor longus, adductor brevis, adductor magnus

what plane do adductors move in

frontal AND sagittal plane

near full flexion, adductors produce what (sagittal plane)

hip extension

near full extension, adductors produce what

hip flexion

primary hip abductors

gluteus medius, TFL, gluteus minimus

What plane do abductors control the pelvis in

frontal plane, preventing contralateral hip drop

what muscle group accounts for most of the compressive forces of the femoral head into the acetabulum

abductors

primary/secondary hip IR at neutral stance

NO PRIMARY HIP IR AT NEUTRAL

Secondary IR: adductors, glute min/med (anterior fibers)

With hip flexion to 90 degrees or more internal rotation torque increases due to changing muscle pull direction.

Some external rotators can even become internal rotators when hip is flexed.

active insufficiency

when a multi joint muscle is not at an optimal length to further shorten and develop maximal force

A muscles force is limited due to its short length (length tension curve)

passive insufficiency

when a multi joint muscle is lengthened beyond its optimal optimal length, thereby passively resisting full motion

a muscle will limit range of motion at a joint because it is over stretched over two joints