Coronal Alignment in TKA: Traditional Principles Versus New Concepts

Background: Up to 20% of total knee arthroplasty (TKA) patients are not satisfied with their outcome, and coronal alignment is considered an important variable in attaining a well-functioning TKA. Neutral mechanical alignment is not necessarily the anatomic norm and has led some surgeons to advocate a shift in defining and attaining the optimal coronal component alignment. Our aim was to review the different coronal alignment paradigms of TKA and summarize the historical and contemporary outcomes of different alignment techniques. Methods: A systematic review was performed in March 2017 via PubMed using the search terms: coronal alignment, kinematic alignment, and total knee replacement using Boolean “and” in-between terms. Relevant results were then reviewed, analyzed and summarized  Conclusions: Early clinical outcomes of kinematically aligned TKAs are promising, but long-term clinical results are unknown. Clinical, laboratory, and retrieval studies suggest that mechanical varus in TKA, especially involving the tibial component, may result in earlier failure. Kinematic alignment with boundaries may be an optimal strategy for patients with pre-operative constitutional varus or congenital tibia vara.