Does lateral versus medial exposure influence total knee tibial component final external rotation? A CT based study

Area of Science:

• Orthopedic Surgery
• Biomedical Engineering
• Radiology

Background:

• Previous studies suggest lateral approaches in total knee arthroplasty (TKA) improve patellar tracking.
• This study investigates if increased tibial component external rotation is responsible for these benefits.

Purpose of the Study:

• To compare tibial component rotation between lateral and medial surgical approaches in TKA.
• To analyze the influence of surgical approach on patellar positioning.

Main Methods:

• Retrospective analysis of 45 postoperative CT scans (15 lateral, 30 medial approaches).
• Measurement of tibial component rotation angle and anterior tibial tuberosity (ATT) position.
• Utilized a posteriorly stabilized, fixed-bearing TKA design.

Main Results:

• The lateral approach group showed significantly less ATT lateralization (1 ± 4mm vs. 7 ± 3mm) and reduced tibial component external rotation (2° vs. 18°).
• A statistically significant difference (p<0.0001) was observed for both measurements between the groups.

Conclusions:

• The lateral surgical approach substantially increases tibial component external rotation compared to the medial approach.
• Improved visualization of the lateral tibial plateau during the lateral approach likely contributes to this rotational difference.
• This increased external rotation is believed to enhance postoperative patellar tracking.