Coronal alignment in total knee arthroplasty: just how important is it?

Area of Science:

• Orthopedic Surgery
• Biomechanical Engineering
• Medical Device Research

Background:

• Traditional orthopedic principles suggest neutral alignment maximizes total knee arthroplasty (TKA) survival.
• Recent evidence questions the superiority of perfectly neutral alignment in TKAs.
• Understanding coronal alignment's impact on revision rates is critical for surgical outcomes.

Purpose of the Study:

• To investigate the relationship between postoperative coronal alignment and revision rates in primary total knee arthroplasties.
• To determine if deviations from neutral alignment (outliers) predict TKA failure.
• To identify an optimal alignment range for improved TKA survival.

Main Methods:

• Retrospective analysis of 6070 primary TKAs from 3992 patients.
• Stratification of knees into neutral, varus, and valgus alignment groups based on postoperative tibiofemoral angle.
• Comparison of failure rates across alignment groups to assess revision predictors.

Main Results:

• Overall revision rate was 0.84% (51 failures).
• Neutral alignment group had 0.5% failure, varus 1.8%, and valgus 1.5%.
• Best survival observed for alignments between 2.4 and 7.2 degrees of valgus; outliers showed higher revision rates.

Conclusions:

• Deviations from neutral alignment, particularly varus, are associated with increased TKA revision.
• Optimal TKA survival is achieved within a specific valgus alignment range (2.4–7.2 degrees).
• Surgical goals for TKA should focus on achieving this optimal valgus alignment to enhance long-term implant success.