Inter- and intra-observer errors in identifying the transepicondylar axis and Whiteside's line

Area of Science:

• Orthopedic surgery
• Biomechanics
• Anatomy

Background:

• Accurate rotational alignment is crucial for successful total knee arthroplasty (TKA).
• The transepicondylar axis and Whiteside's line are commonly used landmarks for guiding femoral component rotation.
• Understanding the reliability of these landmarks is essential for improving surgical outcomes.

Purpose of the Study:

• To evaluate the inter- and intra-observer variability in identifying the transepicondylar axis and Whiteside's line.
• To assess the accuracy of these landmarks in a cadaveric model simulating TKA procedures.

Main Methods:

• Four cadaveric knees were dissected to identify the transepicondylar axis and Whiteside's line.
• Three observers (two surgeons, one trainee) repeatedly identified these landmarks.
• Landmark identifications were compared to true values obtained after soft tissue removal.

Main Results:

• Significant inter-observer errors were found for both the transepicondylar axis and Whiteside's line (p<0.001).
• Intra-observer variation was higher for Whiteside's line (SD 4.2°) compared to the transepicondylar axis (SD 2.5°).
• Maximum potential errors reached 13° for the transepicondylar axis and 24° for Whiteside's line.

Conclusions:

• The accuracy of rotational alignment using these landmarks is operator-dependent.
• Low intra-operative reproducibility of the transepicondylar axis and Whiteside's line was observed.
• These findings highlight potential challenges in achieving precise rotational alignment during TKA.