Staging Bilateral Total Knee Arthroplasties Reduces Alignment Outliers

Area of Science:

• Orthopedic Surgery
• Biomedical Engineering
• Radiology

Background:

• Patients with bilateral knee osteoarthritis often opt for simultaneous total knee arthroplasties (TKAs).
• Technical variations between simultaneous and staged TKAs may influence clinical and radiographic results.
• A hypothesis proposed that staged TKAs would exhibit fewer mechanical alignment outliers than simultaneous TKAs.

Purpose of the Study:

• To compare the mechanical alignment and complication rates of simultaneous versus staged total knee arthroplasties (TKAs).
• To investigate potential differences in radiographic outcomes between the two surgical approaches for bilateral knee replacements.

Main Methods:

• A retrospective review of 87 simultaneous and 72 staged TKAs with a minimum 2-year follow-up.
• Radiographic assessment using standing long leg and lateral knee views.
• Coronal and sagittal measurements were analyzed by blinded observers with high intraobserver and interobserver reliability.

Main Results:

• The second knee in simultaneous TKAs was significantly more likely to have its mechanical axis outside neutral alignment (49%) compared to staged TKAs (28%).
• Staged TKAs showed an increased risk of deep venous thrombosis (DVT) (OR 2.96).
• No significant differences were observed in other perioperative complications, range of motion, or Knee Society Score.

Conclusions:

• Simultaneous TKAs present a higher risk of malalignment in the second knee compared to staged procedures.
• Surgeon and system-related factors may contribute to malalignment in simultaneous TKAs.
• Long-term clinical outcomes and the risk of radiographic loosening warrant further investigation.