tka navigation for severe deformations pascal a. vendittoli, md msc frsc montréal, canada

TKA Navigation for severe deformations

Pascal A. Vendittoli, MD MSc FRSC

Montréal, Canada

How good are we

without surgical

navigation ?

0

5

10

15

20

25

30

35

40

Valgus VarusMechanical axis

0° 2° 4° 6° 8°2°4°6°8°

%

NavigatedControls

Navigation reduces outliers

Jenny, ESSKA 2002

Pourquoi la navigation?

Radiographie simple2 plans: frontal et sagital

Ombre de la réalité…

angulation et translation

rotation?

FemurDeformation

exceed instrument with preset

angle(7°: Varus - 4°: Valgus)

Deformed or obliterated intra medullary canal

Extra medullary alignment + fluoroscopy

Lateral alignment almost impossible…

Extra-medullary instrument

Translation

Is there a tool available to help us?Yes : computer assisted surgery

Can Navigation Do Everything?

NO…

• Planification is still the key for success

Grandeur + Niveau de la déformation

Donc il n’existe pas d’indication absolueAssociation de l’angle + le niveau = l’indication

Example: 20 degree valgus deformity

Intra articular correction vs

summit of the deformity?

Not decided on #degrees….

• Collateral ligaments attachment

• Joint line obliquity

• Age and possible use of TS implant

Limiting Factor: Coll Ligaments

25-30 mm

222-28 mm

Maximum 7-10 mm

If more:3 options

-corrective osteotomy-epicondyle transfert -constrained implant

When your plan is made, use thePower of Computer Assisted Surgery

• Follow intra operatively your pre op planning

• Make small adjustments according to intra op findings

• Feel confident that what you expect is what you will get…

25 degresComplete correction:

OversizeorFlexion instability

No correction=Post Impingement

10 degres flexionAnterior appositionTo maintain post space

Sagital 15 degres

flexion of the implant=undersize

5 degres extension of the implant

Young patient 45 y Full medial release = still unbalancedKept 3 degres varusto avoid constrained implant

Sagital plan =4 degres of extension

Discussion

• I do use navigation for all my primary TKA: ASM

• I only use full navigation for deformed cases

Advantages:— Be familiar with the unusual anatomy— Intra operative fine tunning…— Avoiding difficult hardware removal— Full extention ?

— Increased time (20 minutes) is compensated in the deformed cases (fluoroscopy, time spent for adjustment, etc.)

RotationFémur

Col fémoralCondyles post.

14° ext.

Tibia

Plateaux postérieurs

Malléoles 26 ° ext.

Sites contributoires Sommetde la

déformation

CortexAxes mécaniques

Axes anatomiques

Niveau de la déformation

• Proche du genou : malalignement• Loin du genou : malorientation