Stems
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
cemented
Conformity Materials Fixation Gender
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 120o due to posterior impingement of the tibial component
Cemented femur
Goals in femoral cementing
Optimize cement-bone interface
Cement mantle free of defects
Minimum 2 mm thickness
Femoral component centred in cement mantle
Survival
Swedish Joint Registry
Reflection All Poly / Spectron 92% 10 year
Cemented acetabulum
Indications
Neoplastic / metastatic
Severe osteoporosis
Pagets
Longetivity
Ranawat
- longevity directly related to quality of cement penetration into acetabulum
Types
Reflection all Poly (S&N)