Table 1 Overview of different alignment strategies
Alignment | Tibia cut | Soft tissue release | Distal femur cut | HKA | Gaps goals | Rotation | |
|---|---|---|---|---|---|---|---|
Tibia first | Mechanical | Always 0° | Osteophytes removal, capsular release, ligament release (pie crusting) | Always 0° | Always 0° | Equal | Always 3° ER |
Adjusted Mechanical | Always 0° | Depends on extension gap difference (3° varus-3° valgus) | Between 3° varus and 3° valgus | Equal | Depends on flexion gap difference (up to 9° ER) | ||
Constitutional Varus | Depends on MPTA | Similar to MA | Always 0° | Between 3° varus and 0° | Equal or Flexion > Extension (2mm) | 3° less ER compared to AMA | |
Anatomic | 2–3° varus | Over release 2–3 mm | 3° of valgus | Always 0° | Equal | 3° less ER compared to AMA | |
Inverse Kinematic | Depends on cartilage loss | No release | Depends on tibia | Between 5° varus and 3° valgus | Lateral flexion gap > medial flexion gap | 4–6° less ER compared to AMA | |
Functional | Depends on cartilage loss | Minimal (dMCL) | Depends on extension gap difference (5° varus-5° valgus) | Between 5° varus and 5° valgus | Lateral flexion gap > medial flexion gap | 4–6° less ER compared to AMA | |
Femur first | Kinematic | Depends on femur cuts and gap difference | Minimal | Depends on cartilage loss and individual anatomy | Between 5° varus and 5° valgus | Lateral flexion gap > medial flexion gap | Depends on cartilage loss and individual anatomy |
Restricted Kinematic | Depends on femur cuts and gap difference | Minimal | Depends on cartilage loss and individual anatomy | Between 3° varus and 3° valgus | Lateral flexion gap > medial flexion gap | Depends on cartilage loss and individual anatomy |