Morphological Asymmetry of Pelvic Rings: A Study Based on Three-Dimensional Deviation Analysis

Area of Science:

• Anatomy
• Medical Imaging
• Biomechanical Engineering

Background:

• Morphological asymmetry of the pelvic ring is a known phenomenon.
• Understanding the extent and distribution of this asymmetry in healthy individuals is crucial for clinical applications.
• Three-dimensional (3D) geometric analysis offers a precise method for quantifying asymmetry.

Purpose of the Study:

• To quantitatively evaluate the three-dimensional (3D) morphological asymmetry of pelvic rings in healthy adults.
• To compare the asymmetry between the entire pelvic ring and its constituent parts (hip bones).
• To identify specific anatomical regions within the pelvis that exhibit higher degrees of symmetry.

Main Methods:

• Retrospective analysis of CT images from 159 healthy subjects (aged 20-59 years).
• Reconstruction of 3D digital pelvic ring and hip bone models.
• 3D deviation analysis comparing original models with their mirrored counterparts to quantify asymmetry using average deviation (AD) and maximum deviation (MD).

Main Results:

• Nearly all (98.74%) pelvic rings exhibited maximum deviations (MDs) over 4mm, indicating widespread asymmetry.
• Pelvic rings showed significantly higher asymmetry (MD 7.46mm) compared to bilateral hip bones (MD 6.08mm).
• Specific regions like the iliac crest showed high asymmetry (74.8% > 4mm MD), while the obturator foramen region was more symmetric (9.4% > 4mm MD).

Conclusions:

• Significant pelvic ring asymmetry is prevalent in the general healthy population.
• Certain anatomical sub-regions of the pelvis demonstrate notable 3D geometric symmetry.
• Focusing on restoring symmetry in specific anatomical regions may be more effective than aiming for overall pelvic ring symmetry in surgical interventions.