This 2021 current concepts review from Lustig et al. defines and distinguishes four personalized TKA alignment strategies. It clarifies their principles, surgical techniques, and available outcome data. The review responds to inconsistent functional results seen with traditional neutral mechanical alignment.
TKA dissatisfaction rates of 75%–89% with mechanical alignment (Bonnin et al., cited in this paper) drove the search for personalized approaches — yet until this review, the four emerging strategies were inconsistently defined and easy to conflate.
When planning TKA, use this framework to distinguish the strategies: Kinematic alignment: femur resurfaced first, tibial cut balances the gaps Inverse kinematic alignment: tibia resurfaced first (equal medial/lateral cuts), femoral cuts balance the gaps. Requires robotics Restricted kinematic alignment: KA principles applied within safe zones (individual cuts ≤5° from mechanical axis; HKA ≤3° from neutral). Use this for moderate-to-severe deformity Functional alignment: robotic intraoperative fine-tuning of all parameters. No clinical outcome data yet
When a patient has moderate or severe varus (10°+), kinematic alignment without restriction increases tibial stress by 25–32% over mechanical alignment. Restricted KA is the appropriate personalized option in that scenario, not unrestricted KA.
Counsel patients that none of the personalized techniques yet has long-term survivorship data equivalent to mechanical alignment. The 10-year unrestricted KA data (97.5% survival) is promising but comes from a single series.
This 2021 current concepts review from Lustig et al. defines and distinguishes four personalized TKA alignment strategies. It clarifies their principles, surgical techniques, and available outcome data. The review responds to inconsistent functional results seen with traditional neutral mechanical alignment.
TKA dissatisfaction rates of 75%–89% with mechanical alignment (Bonnin et al., cited in this paper) drove the search for personalized approaches — yet until this review, the four emerging strategies were inconsistently defined and easy to conflate.
When planning TKA, use this framework to distinguish the strategies: Kinematic alignment: femur resurfaced first, tibial cut balances the gaps Inverse kinematic alignment: tibia resurfaced first (equal medial/lateral cuts), femoral cuts balance the gaps. Requires robotics Restricted kinematic alignment: KA principles applied within safe zones (individual cuts ≤5° from mechanical axis; HKA ≤3° from neutral). Use this for moderate-to-severe deformity Functional alignment: robotic intraoperative fine-tuning of all parameters. No clinical outcome data yet
When a patient has moderate or severe varus (10°+), kinematic alignment without restriction increases tibial stress by 25–32% over mechanical alignment. Restricted KA is the appropriate personalized option in that scenario, not unrestricted KA.
Counsel patients that none of the personalized techniques yet has long-term survivorship data equivalent to mechanical alignment. The 10-year unrestricted KA data (97.5% survival) is promising but comes from a single series.