Biomech of N &Amp; TKR Knee

8/6/2019 Biomech of N &Amp; TKR Knee

1/77


2/77

BIOMECHANIC

S

OFNORMAL

&REPLACED KNEE

BIOMECHANIC

S

OFNORMAL

&REPLACED KNEE


3/77


4/77

BIOMECHANICSBIOMECHANICS

KNEE :Force closedmechanism

HIP :Self closed

mechanism


5/77

The Axis Of Lower

Limb

The Axis Of Lower

LimbVertical Axis

Mechanical Axis

Anatomical Axis of Femur

Anatomical Axis of Tibia

Vertical Axis

Mechanical AxisAnatomical Axis of Femur

Anatomical Axis of Tibia


6/77


7/77


8/77

Tibio-Femoral

Motion

Tibio-Femoral

MotionFlexion Extension

Abduction Adduction

Internal ExternalRotation

Flexion Extension

Abduction Adduction

Internal ExternalRotation


9/77

Instantaneous centre ofmotion

Instantaneous centre ofmotion

FLEXION -

EXTENSION

FLEXION -

EXTENSION


10/77

Instantaneous centerathwa

Instantaneous centerpathway

FLEXION -

EXTENSION

FLEXION -

EXTENSION


11/77

Sliding/RockingSliding/Rocking


12/77

FLEXION -

EXTENSION

FLEXION -

EXTENSION

Sliding/Rocking of femurSliding/Rocking of femur


13/77Gliding/Rolling


14/77

FLEXION -

EXTENSION

FLEXION -

EXTENSION

Gliding/Rolling of femur


15/77

FLEXION -

EXTENSION

FLEXION -

EXTENSION

Knee glides & Slides

Rocks & Rolls!

Knee glides & Slides

Rocks & Rolls!


16/77


17/77

ROTATION OF KNEEROTATION OF KNEE

Screw home

movement

Rotation increases as

knee is flexed

Arc ranges 30 60

Screw home

movement

Rotation increases as

knee is flexed

Arc ranges 30 60


18/77

Abduction - AdductionAbduction - Adduction

Normal angulationof 7 Degrees with

knee extendedMotion permitted

by cruciate andcollaterals

No movement inflexion

Normal angulationof 7 Degrees with

knee extendedMotion permitted

by cruciate andcollaterals

No movement inflexion


19/77

FlexionFlexion40

0

40

Extension

Extension

HS

FF

FF

HO

TOTO


20/77


21/77


22/77

Flexion -

Extension

Flexion -

Extension

Sit & Risefrom a chair

90 -110degrees

Sit & Risefrom a chair

90 -110degrees


23/77

Flexion -

Extension

Flexion -

Extension

Descending stairs 90 degreesDescending stairs 90 degrees


24/77

Flexion -

Extension

Flexion -

Extension

Ascending stairs 82 degrees

Ascending stairs 82 degrees


25/77

Int Ext RotationInt Ext Rotation

Normal 30-60 Degrees

13 degrees in normalwalking

More in stair walking

More on rough groundwalking

Normal 30-60 Degrees

13 degrees in normalwalking

More in stair walking

More on rough groundwalking

d li dL d A li d t


26/77

Loads Applied to

Knee

Loads Applied toKnee

3X - in Level Walking4X in Stair Climbing

Area of Contact is less in Flexion

Medial side bears more weight

3X - in Level Walking4X in Stair Climbing

Area of Contact is less in Flexion

Medial side bears more weight


27/77

STABILITYSTABILITY

Surfacegeometry

Muscles crossingthe joint

Ligaments andcapsule

Menisci

Surfacegeometry

Muscles crossingthe joint

Ligaments andcapsule

Menisci

SURFACESURFACE


28/77

SURFACE

GEOMETRY

SURFACEGEOMETRY

Femur is convex

Tibia is concave mediallyTibia is convex laterally

Tibial eminence aids in stability

Femur is convex

Tibia is concave mediallyTibia is convex laterally

Tibial eminence aids in stability

MUSCLEMUSCLE


29/77

Resists deforming forceResists slow forces

Increase joint

compression

Increase stability

Resists deforming forceResists slow forces

Increase joint

compressionIncrease stability

MUSCLE

S

MUSCLE

S


30/77

Resists motion

Resists translatorymovement

Resists motion

Resists translatorymovement

Resists excessive rotation

LIGAMENTSLIGAMENTS


31/77

Joint conformityVarus valgus

stability

Resists translation

Joint conformityVarus valgus

stability

Resists translation

MENISCUSMENISCUS


32/77

IDEAL KNEEIDEAL KNEE

Extends fully & achieves excellent stability

Flexes beyond 110 & still retains stability

Gliding and sliding occurs simultaneously

Allows more rotation as knee flexes

Articular contact maximum throughout range

Extends fully & achieves excellent stability

Flexes beyond 110 & still retains stability

Gliding and sliding occurs simultaneously

Allows more rotation as knee flexes

Articular contact maximum throughout range


33/77

Reduplicate the function of menisci

Reduplicate the function of cruciates

Achieve excellent ligament balance

Have anatomic femur & tibial surface

Reduplicate the function of menisci

Reduplicate the function of cruciates

Achieve excellent ligament balance

Have anatomic femur & tibial surface

IDEAL KNEEIDEAL KNEE


34/77

RESTORATION OF

MECHANICAL AXIS

RESTORATION OF

MECHANICAL AXIS


35/77


36/77


37/77


38/77


39/77


40/77


41/77


42/77


43/77

RESTORATION OFMECHANICAL AXIS

RESTORATION OFMECHANICAL AXIS

Perpendicular

to the

Mechanical &Anatomical

axis of the

Perpendicular

to the

Mechanical &Anatomical

axis of the


44/77


45/77


46/77


47/77

BIOMECHANICS OF

TKR

BIOMECHANICS OF

TKR

Shouldnone, one orbothcruciate

ligaments be

Shouldnone, one orbothcruciate

ligaments be

ACL & PCLACL & PCL


48/77

ACL & PCLSACRIFICED

ACL & PCLSACRIFICED

Conformingconcave surface oftibia producing

inherent stability Long term results

from HSS still

remains the goldstandard

Conformingconcave surface oftibia producing

inherent stability Long term results

from HSS still

remains the goldstandard

TOTAL CONDYLARTOTAL CONDYLAR


49/77

Limited knee motion

Tibial componentsubluxated posteriorly

Stair climbing was

difficult

Limited knee motion

Tibial componentsubluxated posteriorly

Stair climbing was

difficult

TOTAL CONDYLARDESIGNS


TOTAL CONDYLARTOTAL CONDYLAR


50/77




51/77

RETAIN THE PCLRETAIN THE PCL

PCL roll back in flexion

Roll back needs flat tibial surface

PCL roll back in flexion

Roll back needs flat tibial surface


52/77

ROLL BACK WITH PCLROLL BACK WITH PCL


53/77

More arc of

motion

Intact PCLprevents post

subluxation of

tibia Stability is

increased

Decreased

More arc of

motion

Intact PCLprevents post

subluxation of

tibia Stability is

increased

Decreased



54/77

Proprioception is better

Retention of PCL helps in

maintaining the joint line

Proprioception is better

Retention of PCL helps in

maintaining the joint line



55/77

Why surgeon sacrifices

PCL?

Why surgeon sacrifices

PCL?

Minimum tibial resection

Easier surgical technique

Easier correction of

deformity

Minimum tibial resection Easier surgical technique

Easier correction of

deformity

PCL


56/77

PCL

SUBSTITUTING KNEE

PCL

SUBSTITUTING KNEE

Spine & Cam mechanism Produces roll back

Prevents posterior subluxation

Spine & Cam mechanism Produces roll back

Prevents posterior subluxation

PCLPCL


57/77

Anterior tibial subluxation

not prevented

Does not substitute

collaterals

Posterior slope in tibianecessary

Anterior tibial subluxation

not prevented

Does not substitute

collaterals

Posterior slope in tibianecessary

PCLSUBSTITUTINGKNEE

PCLSUBSTITUTINGKNEE

PCLPCL


58/77

PCLSUBSTITUTINGKNEE

PCLSUBSTITUTINGKNEE

PCLPCL


59/77

PCLSUBSTITUTINGKNEE

PCLSUBSTITUTINGKNEE Bad for valgus knee

Wear of spine

Bone loss

Bad for valgus knee

Wear of spine

Bone loss

PCL SUBSTITUTING


60/77

Can we substitute the PCL byultra congruent insert ?

Can we substitute the PCL byultra congruent insert ?

PCL SUBSTITUTING

KNEE

PCL SUBSTITUTING

KNEE

PCL SUBSTITUTING


61/77

PCL SUBSTITUTING

KNEE

PCL SUBSTITUTING

KNEE Patellectomy

Old PCL injury

Over release of PCL

Inflammatory

conditions ?

Patellectomy

Old PCL injury

Over release of PCL

Inflammatoryconditions ?

MENISCAL BEARINGMENISCAL BEARING


62/77

MENISCAL BEARINGKNEE

MENISCAL BEARINGKNEE

ACL, PCL retaining

PCL retaining

ACL, PCL retaining

PCL retaining

ROTATING PLATFORMROTATING PLATFORM


63/77

ROTATING PLATFORMKNEE

ROTATING PLATFORMKNEE

Cruciate sacrificing

Spin off

Undersurface wear

Cruciate sacrificing

Spin off

Undersurface wear


64/77

FEMURFEMUR Anatomic

Decreaseradius of

curvature

posteriorly

Anatomic

Decreaseradius of

curvature

posteriorly

EXTERNAL ROTATION OFEXTERNAL ROTATION OF


65/77

EXTERNAL ROTATION OFFEMUR




66/77





67/77



TIBIALTIBIAL


68/77

TIBIAL

TRAY

TIBIAL

TRAY

Concave conforming

No rotation in extension

Intercondylar eminence to prevent

translocation

Anterior Posterior margin equal

height

Concave conforming

No rotation in extension

Intercondylar eminence to prevent

translocation

Anterior Posterior margin equal

height

TIBIALTIBIAL


69/77

AnatomicAnatomic

TIBIAL

TRAY

TIBIAL

TRAY


70/77

PATELLAPATELLA


71/77

PATELLAPATELLA


72/77

Recent thoughtsRecent thoughts Adductor moment

Rotatory arthritis ofknee (RAK)

Does tibia really slopeposteriorly?

Adductor moment

Rotatory arthritis ofknee (RAK)

Does tibia really slopeposteriorly?


73/77

Adductor MomentAdductor Moment


74/77

Rotatory Arthritis of KneeRotatory Arthritis of Knee

Deformities in Knee are

triplanar frontal,saggital & coronal

ACL s role Soft tissue involvement

Deformities in Knee are

triplanar frontal,saggital & coronal

ACL s role Soft tissue involvement


75/77

Posterior slope of tibiaPosterior slope of tibia


76/77


77/77

Biomech of N &Amp; TKR Knee

Documents

Transcript of Biomech of N &Amp; TKR Knee