uncemented

Concept

1. Initial press fit with mechanical stability

Advantage

1.  Reduce implant loosening

- offset load sharing to diaphysis

- 30% if > 70 mm

2. Restore optimal alignment

Indications

1.  Using augments or bone grafting

2.  Increased constraint 

- VVS / hinge

Conformity

Definition

Geometric measure of the closeness of the fit of the knee articulation

Concepts

The ideal TKA maximises articular conformity while minimising axial constraint

Highly conforming / Fully congruent

- constant sagittal femoral radius

- large contact areas

- theoretical limitation of flexion to 120^o due to posterior impingement of the tibial component

Goal

Initial press fit

- implant geometry fits the cortical bone in the proximal femur

- good initial mechanical stability

Biological fixation for success

- good press fit

- minimal micromotion

- bony or fibrous tissue ingrowth or ongrowth