Individual Bilateral Difference of Femur, Tibia, and Leg Rotation: A Clinical Study of 141 Healthy Japanese...

Area of Science:

• Orthopedic Surgery
• Radiology
• Anatomy

Background:

• Femur and tibial malrotation after surgery is a known complication.
• Previous studies on individual bilateral differences (IBDs) in rotation have not focused on the Japanese population.
• Computed tomography (CT) has identified IBDs in femur and tibial rotation in American populations.

Purpose of the Study:

• To evaluate femur, knee, tibia, and leg rotation, including sex differences and IBDs, in a healthy Japanese population using CT analysis.
• To determine if IBDs in rotation are clinically significant in Japanese individuals.
• To provide data that can inform surgical planning for femur and tibial procedures in Japan.

Main Methods:

• CT analysis of 141 healthy Japanese individuals (70 men, 71 women).
• Measurement of bilateral axial femur, knee, tibia, and leg rotation alignment.
• Analysis of distribution, sex differences, and IBDs using absolute bilateral difference (ABD) and relative bilateral difference (RBD).

Main Results:

• Mean ABD for femur rotation was 6.5° (95% within ≤15°).
• Mean ABD for tibia rotation was 5.1° (89% within ≤10°).
• Right tibia showed significantly higher mean external rotation (3.3°) compared to the left.

Conclusions:

• The distribution of ABD in femur and tibia rotation aligns with established acceptable rotation differences (≤15° and ≤10°, respectively).
• Higher external rotation on the right tibia should be considered during surgical interventions.
• Significant sex differences in rotation were observed, but not in bilateral differences.