Practical

filercaliforniaΜηχανική

14 Νοε 2013 (πριν από 4 χρόνια και 9 μήνες)

451 εμφανίσεις

Lecturer:


Dr.
Manal

Radwan

Salim


Demonstrators:



Dr.Mohammed

Arafaat



Dr.
Haytham

Essawy




Dr.
Atef

Mohammed



Dr. Mai
Tolba



3
rd

practical section Fall
2013
-
2014

20
-
10
-
2013

Arthrology

and

Movements

a)
Lateral

and

medial

tibiofemoral
:

Consist of articulation between large convex femoral
condyles, and nearly flat and smaller tibial
condyles.


b)

Patellofemoral
:

Knee

stability

depends

mainly

on

soft

tissue

constraints

rather

than

bony

configuration
.

occur

about

medio
-
lateral

axis

of

rotation
.

In

general

a

healthy

knee

rotates

from

130
-
to

140

degrees

of

about

5

to

10

degrees

of

hyperextension
.

The
mediolateral

axis or
rotation is not a fixed point by
migrates within the femoral
condyles, as it is influenced
by the
ecentric

configuration
of the femoral condyles.

Tibio
-
fermoral

joint flexion / extension

movements:

a)
During

tibial

on

femoral

extension

“open

kinematics

chain”
:

The

articular

surface

of

the

tibia

rolls

and

slides

anteriorly

on

the

femoral

condyles
.

The

meniscus

are

shown

to

be

pulled

anteriorly

by

quadriceps

muscle
.

*
Active

extension

of

the

knee
:


The

importance

of

the

sliding

movements

of

tibia

and

femur

during

active

flexion

and

extesnion

(rolling)

is

that

it

allow

allow

the

larger

diameter

of

the

spherical

femoral

condyles

to

roll

over

a

much

smaller

transverse

surface

of

the

tibial

plataeu
.

b)

During

femoral

on

tibial

extension

“closed

kinematics

chain
:



as

in

standing

up

from

a

deep

squat

position,

the

femoral

condyles

simultaneously

roll

anteriorly

and

slide

posteriorly

on

the

articular

surface

of

the

tibia
.

a)

During

tibial

on

femoral

flexion

“open

kinematics

chain”
:

The

articular

surface

of

the

tibia

rolls

and

slides

posteriorly

on

the

femoral

condyles
.

The

meniscus

are

shown

to

be

pulled

posteriorly

by

popliteus

muscle
.

*
Active

flexion

of

the

knee
:


b)

During

femoral

on

tibial

flexion

“closed

kinematics

chain
:


as

in

moving

from

erect

standing

to

deep

squat

position,

the

femoral

condyles

simultaneously

roll

posteriorly

and

slide

anteriorly

on

the

articular

surface

of

the

tibia
.

Tibio
-
fermoral

joint

internal

/

external

rotation

movements
:

*Internal

/

external

rotation

movements

occur

about

vertical

or

longitudinal

axis

of

rotation
.


*Rotation

degree

of

knee

increases

with

greater

knee

flexion
.

A

knee

flexed

90

degrees

permits

about

40

-
50

degrees

of

total

rotation,

with

external

rotation

range

exceeds

rotation

of

internal

rotation

by

a

ration

2
:
1

*In

full

extension,

no

rotation

is

allowed

in

fully

extended

knee
.

*Rotation

occur

either

by

tibial

rotation

on

femur

in

open

kinematic

chain

activities,

or

femur

rotating

on

tibia

in

a

closed

kinematic

chain

activities
.

Generally

speaking

to

all

rotating

joints

(hip,

shoulder,

knee)

the

rotation

direction

(internal

or

external)

is

named

according

to

direction

of

movement

of

the

distal

bony

segment

of

the

joint
;

for

example

knee

rotation

is

named

according

to

movement

direction

of

tibia

even

if

the

moving

part

is

the

femur

in

closed

kinematic

chain
.

*In

Tibiofemoral

rotation

(open

kinematic

chain)
:



In

internal

rotation
:

the

tibia

internally

rotate,

foot

moves

to

points

medially
.

In

external

rotation
:

the

tibia

externally

rotates,

foot

moves

to

point

laterally
.

*In

Femorotibial

rotation

(Closed

kinematic

chain)

:



In

internal

rotation
:

The

femur

externally

rotate,

foot

fixed

on

ground

in

neutral

the

head

of

femur

moves

(forward)

anteriorly

in

transverse

plane
.

In

external

rotation
:

The

femur

internally

rotate,

foot

fixed

on

ground

in

neutral

the

head

of

femur

moves

backward

(posteriorly)

in

transverse

plane
.

Locking

knee

on

full

extension

requires

knee

rotation

about

10

degrees
.

Screw

home

rotation

is

different

from

axial

rotation

that

occur

at

knee

it

is

a

conjunct

rotation,

linked

mechanically

to

flexion

and

extension

kinematics

and

cant

be

performed

independently
.

Based

on

observable

twisting

of

knee

during

last

30

degrees

of

extension
.

*In

tibiofemoral

extension
:

the

tibia

externally

rotates

about

10

degrees
.

*In

femorotibial

extension

(rising

from

squat)
:

The

femur

internally

rotates

on

fixed

tibia
.


*Regardless

whether

tibia

or

femur

is

rotating

the

knee

is

externally

rotated

10

degrees

when

fully

extended
.


To

observe

the

screw

home

mechanism
:

at

the

knee,

have

the

partner

sit

with

the

knee

flexed

to

about

90

degrees
.

Draw

a

line

on

the

skin

between

the

tibial

tuberosity

and

the

apex

of

the

patella
.

After

completing

full

tibial


on

femoral

extension,

redraw

this

line

between

the

same

landmarks

and

note

the

change

in

position

of

the

externally

rotated

tibia
.


to

unlock

the

knee

that

is

fully

extended,

the

joint

must

first

internally

rotate

by

poplitues

muscle

that

is

both

internal

rotator

and

flexor

of

the

knee

joint,

the

muscle

can

rotate

femur

externally

to

initiate

femoral
-
on

tibial
.

flexion,

or

rotate

the

tibia

internally

to

initiate

tibial


on
-

femoral

flexion
.

As

the

extended

and

locked

knee

prepares

to

flex

(e
.
g
.

when

beginning

to

descend

into

a

squat

position),

the

popliteus

provides

an

internal

rotation

torque

that

help

mechanically

to

unlock

the

knee
.

In

this

position

the

femur

is

externally

rotated

on

tibia

,

this

action

on

femur

is

readily

seen

by

this

figure

showing

line

of

pull

of

popliteus

1
-

shape

of

medial

femoral

condyle
:

as

it

curves

30

degree

laterally

as

it

approaches

the

intercondylar

grove
.

And

as

and

extends

further

anteriorly

than

the

lateral

condyle
.

Thus

tibia

must

follow

this

path

during

tibial

on

femoral

extension
.

2
-

passive

tension

in

the

anterior

cruciate

ligament

3
-

lateral

pull

of

quadriceps

tendon
.

c) Tibial mechanical /
anatomical axis:
-

centre plateau to centre
of talus / ankle


Knee joint alignment as in x ray :

Femoral

mechanical

axis
:
-

centre

of

femoral

head

to

centre

knee
.

b) Femoral
anatomical
axis”:
-

centre
of femoral shaft
to center of
knee joint.
6
o

outwards from
mechanical axis.

1
-

identify bony land marks that marks the beginning
and ends of each bony segments (forming the tested
joint and marks them by colored markers.


2
-
Fotograph patient in the desired functional position
with marks on bony segments ends.


3
-

Using AutoCAD program draw a straight line that
connect between bony segment ends marks.

This line represents
the mechanical or anatomical axis
of the bony segment .


4
-

Measure the angle between the two drawn
anatomical axes.

Assessment of joint alignment using motion
analysis:

1
-

Identify

bony

land

marks
:


a)

Femoral

mechanical

axis
:

from

centre

of

femoral

head

(

3

fingers

medial

to

ASIS)

to

centre

knee(mid

point

between

medial

and

lateral

femoral

epicondyles
)
.

Or

b)

Femoral

anatomical

axis”
:

-

centre

of

femoral

shaft

(at

same

level

as

greater

trochanter

move

anteriorly

cneter

of

thigh)

to

centre

knee

joint

(as

above)
.

c)

Tibial

mechanical/anatomical

axis

(same)
:

from

center

of

knee

(mid

point

between

medial

and

lateral

femoral

epicondyles
)

to

center

of

ankle

joint

(mid

point

between

lateral

and

medial

maleolus
.



2
-
Fotograph patient in the anatomical position in
frontal view.


3
-

Using AutoCAD program draw mechanical axis
or anatomical axis of femur, mechanical
(anatomical ) axis of tibia.


4
-

Measure the outer angle between the two
drawn axes.

From the above we understand that the exact value
of
varus

or
valgus

of knee depends on method of
measurement whether measuring by anatomical
axis or mechanical axis.


Normal
genu

valgum
: normal
alignment is distal end of femur
makes an angle of 170
-
175
with
the anatomical axis.

note an angle of 170
-
175 degree
equals


5
-
10 degrees
valgus


Note

that

if

measuring

from

mechanical

axis

the

measured

angle

will

increase

to

the

same

person,

i
.
e
.

normal

valgus

degree

is

less?

Some

authors

reported

that

it

is

182

degree,

i
.
e
.

2

degrees

of

varus

A) Excessive
Genu

valgum
(knock
knees)
:


the measured angle lateral is less than
165
degree. i.e.
genu

valgus

degree is >
15
degree

Notes
:

1
-

the

feet

are

separated

from

each

others

more

than

knees
.

2
-

the

angle

opens

laterally



B)
Genu

varum

(bow leg):




the measured angle lateral is
more than
185
degree. i.e.
genu

varum

degree is >
5
degree


Notes
1
-
the feet are nearer to
each others than knee.


2
-
in
varus

the angle opens

medially

1
-

Identify bony land marks:

Femoral anatomical
(mechanical) axis:
from
greater trochanter to knee to
lateral femoral epicondyle.

Tibial anatomical (mechanical)
axis:
from lateral femoral
epicondyle to lateral maleoulus.


2
-
Fotograph patient in the anatomical
position in sagital view.


3
-

Using AutoCAD program draw
femur and tibia bones axes


4
-

Measure the front angle between
the two drawn axes.




the measured angle frontal is
more than
190
degree. i.e.
genu

recarvatum

(hyperextension)degree is >
10
degree


Notes
1
-
the knee
are leveled
beyond the ankle joint