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