Knee Kinematics and Kinetics - Buffalo

Knee Kin
and Ki

nematics
inetics

Definitions:

• Kinematics is the stu

without reference to

http://www.cogsci.princeton.edu/cgi-bin

• Kinetics is the study

reference to forces

udy of movement
forces

n/webwn2.0?stage=1&word=kinematics

of movement with

The Knee:

The largest and most c

• Transmit Loads
• Participate in motion
• Aids conservation of
• Provides a force coup

complex joint structure

n
momentum
ple for body activities

Anatomy o

• 3 Bones

– Tibia, Femur, Patella

• 3 Compartments

– Medial, Lateral, Patel

• 4 Ligaments

– MCL, LCL, ACL, PCL

• 2 Menisci
• Articular Cartilage

of the knee

a
ellofemoral
L

The Kne

ee Joint

Peculiar

• Menisci

– Fibro-cartilage support

• Internal ligaments

– Carry loads during mot

Anatomy

t
tion

Two m

• Outer - lateral menis

– Circular shaped , smal
– Attached to the ACL
– Attached to the femur v

• Inner - medial menis

– “C” shaped
– wider posterior than lat
– attached to the MCL
– attached to the joint ca

menisci

scus

ller ,more mobile

via the ligament of Wrisberg

scus

teral

apsule



Menisci

Menisci F

• Deepen the articula

– Increase area of co

• Shock absorption

– X10 BW
• a skier lands from a

• Increase stability

– Cups the femoral co

• Nutrition of cartilage

– Sweeping synovial

Functions

ation

ontact

a jump

ondyle

e

fluid across joint

Range o

• Need to define planes

in which the particular
motion is taking place

• The knee moves in six

different directions of
motions (6DOF)

– Sagittal plane (0-1400)

of Motion

Tibia-femo
in the sagi

Activity

Walking
Climbing stairs
Descending stairs
Sitting down
Tying a shoe
Squatting

oral motion
ittal plane

Knee Flexion
(degrees)
67
83

s 90
83-110
106
130

Tibio-femo
in the Transv

• Influenced by knee p

– Ex. If knee is in full e
restricted by interlock

• Rotation increases as

– maximum 900 flexion
• External 450
• Internal 300

• Beyond 900

– decreases, due to sof

oral motion
verse plane

position in sagittal plane

extension rotation is
king of condyes with tibia

s the knee is flexed

n

ft tissue restriction

Tibia-femo
in the fron

• Abduction and Adduc

by the amount of kne

– Ex. Full extension pre

• Increased passive ab

adduction occurs wit

oral motion
ntal plane

ction is also affected
nee flexion

ecludes motion

bduction and
th knee flexion < 300

Locating

• Successive films taken 100 in
• Tibia is parallel to the x-ray
• Marking two identifiable poi

points and draw perpendicu

• The intersection point of the

the instant center of rotatio

g an ICR

intervals of flexion (A,B)
y to prevent rotation
ints on femur, and join these
ular bisector (B)
e perpendicular bisectors is
on.

Joint Contact Po

• Two contact points

– @ femur & tibia

¾ Medial

• Translates slightly

anterior on tibia

¾ Lateral

• Translates considerably

posterior on tibia

oints in Flexion

Surface Jo

oint Motion

Types of motio

• Rolling Mo

– Initiates flexio

• Gliding Mo

– Occurs at en

on at knee joint

otion

on

otion

nd of flexion

Rolling

Motion

Gliding

Motion

Instantaneous Ce
IC

• "If one rigid body rotates

body, its motion at any i
by a point or axis of rota
instantaneous center of

• For normal knees

– Pathway of ICR is semic
– Located on the femoral c

enter of Rotation
CR

es about another rigid
instant can be described
ation called the
f rotation.“

circular
condyles

ICR (c

cont’d)

Joint Conta

• Ideally…

we would have
equal distribution
of forces w/o any
varus or valgus
stresses

Figure from Burstein and Wright,
1994

act Forces

Joint Contact Fo

orces in the knee

Joint Contact Fo
(con

• During varus stress

– To balance the stress
• LCL tension rises
• Knee shifts 5° varus
• Increased stress on m

– Repeated cycles of v
• Varus / valgus deform
• Cartilage wear

orces in the knee
nt’d)

s

medial condyle

varus / valgus loading

mity

Patello-fem

moral Joint