TKA Navigation for severe deformations Pascal A. Vendittoli, MD MSc FRSC Montréal, Canada

How good are we without surgical navigation ?

Jenny, ESSKA 2002 Valgus Varus Mechanical axis 0°2° 4° 6°8°2°4°6°8° Navigated: 73% Controls: 62% % Axis 0+2° Multicentric study

Valgus Varus Mechanical axis 0°2°4°6°8°2°4°6°8° % Navigated Controls Navigation reduces outliers Jenny, ESSKA 2002

Pourquoi la navigation? Radiographie simple 2 plans: frontal et sagital Ombre de la réalité… angulation et translation rotation?

Femur Deformation 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 absolue Association 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 mm mm

Maximum 7-10 mm If more: 3 options -corrective osteotomy -epicondyle transfert -constrained implant

When your plan is made, use the Power 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 degres Complete correction: Oversize or Flexion instability No correction = Post Impingement

10 degres flexion Anterior apposition To 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 unbalanced Kept 3 degres varus to 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.)

Rotation Fémur C ol fémoral Condyles post. 14° ext. Tibia Plateaux postérieurs Malléoles26 ° ext.

Sites contributoires Sommet de la déformation Cortex Axes mécaniques Axes anatomiques

Niveau de la déformation Proche du genou : malalignement Loin du genou : malorientation