A New Reference Axis for Tibial Component Rotation in Total Knee Arthroplasty: A Three-dimensional Computed...

Area of Science:

• Orthopedic Surgery
• Biomechanical Engineering
• Medical Imaging

Background:

• Accurate tibial rotation is crucial for successful total knee arthroplasty (TKA) outcomes.
• Existing reference axes for tibial rotation may have limitations in reliability and ease of use.
• Establishing a dependable reference axis is essential for optimizing implant positioning and function.

Purpose of the Study:

• To introduce and validate a novel reference axis, the lateral eminence (LE) line, for assessing tibial rotation in TKA.
• To compare the reliability of the LE line with existing methods, such as Akagi's line and the medial third (1/3) tibial tubercle line.
• To determine the correlation between the LE line and the transverse posterior axis (TPA) in both healthy and osteoarthritic knees.

Main Methods:

• Analysis of 3D tibial models from 80 TKA knees and 80 healthy knees.
• Establishment of a coordinate system based on the standard TKA tibial cut.
• Definition and measurement of the LE line, medial lateral eminence (MLE) line, Akagi's line, and the 1/3 line relative to the Z-axis.
• Measurement of the transverse posterior axis (TPA) in the coronal view.

Main Results:

• The LE line exhibited excellent intra- and inter-observer reliability and reproducibility.
• A moderate correlation was found between the TPA and the LE lines.
• No significant differences in rotational alignment were observed between healthy and osteoarthritic groups across the evaluated reference axes.

Conclusions:

• The novel LE line is a reliable and easily reproducible reference axis for tibial component rotational alignment in TKA.
• The LE line offers a preferable alternative for surgeons seeking consistent and accurate tibial component positioning.
• Further research may explore the long-term clinical impact of using the LE line in TKA outcomes.