Alignment in knee flexion position during navigation-assisted total knee arthroplasty.

Area of Science:

• Orthopedic Surgery
• Biomechanical Analysis
• Medical Technology

Background:

• Total knee arthroplasty (TKA) aims to restore normal knee function and alignment.
• Maintaining neutral limb alignment in both extension and flexion is crucial for optimal TKA outcomes.
• Navigation systems offer enhanced precision in TKA surgery.

Purpose of the Study:

• To evaluate lower limb alignment in knee flexion after navigation-assisted TKA.
• To identify factors correlating with knee flexion alignment.
• To assess the impact of the gap technique on alignment.

Main Methods:

• 120 patients undergoing TKA using a navigation system were prospectively studied.
• Lower limb alignment was measured in knee extension (0°) and flexion (90°).
• Correlations between alignment and preoperative/intraoperative data were analyzed using Pearson's correlation.

Main Results:

• While all cases achieved neutral extension alignment, 30% showed malalignment (varus or valgus) in knee flexion.
• Femoral component rotation relative to the posterior condylar axis showed a strong correlation (r=-0.502) with flexion alignment.
• Weak correlations were found with posterior femoral cut thickness and medial flexion gap.

Conclusions:

• Approximately 30% of patients exhibit knee flexion malalignment despite neutral extension alignment post-TKA.
• Femoral component rotation is a significant factor influencing knee flexion alignment.
• Navigation systems may aid in optimizing femoral component rotation for improved flexion alignment.