Statistical Shape Modeling of the Clavicle: Morphological Variation, Sex Differences, and Surgical Implications

Area of Science:

• Orthopedic surgery
• Biomedical engineering
• Anatomical imaging

Background:

• Clavicle fractures are common, with fixation often complicated by implant mismatch and mechanical failure due to complex clavicular anatomy.
• Existing classification systems for clavicular shape are subjective and fail to account for continuous variations, hindering personalized implant design.
• Large-scale studies on clavicular morphology in Asian populations using advanced modeling techniques are limited.

Purpose of the Study:

• To characterize clavicular morphology in an Asian cohort using statistical shape modeling (SSM).
• To investigate sex- and side-related differences in clavicular shape.
• To evaluate the accuracy of traditional morphological classifications against data-driven groupings.

Main Methods:

• Retrospective analysis of 288 clavicles from 144 Asian adults (94 female, 50 male) using CT scans.
• 3D reconstruction, segmentation, alignment, and statistical shape modeling (Principal Component Analysis) were performed.
• Morphometric parameters were calculated, and statistical tests (t-tests, clustering analysis) assessed sex, side, and classification differences.

Main Results:

• The first six modes of variation (MoV) explained 82.38% of total variance, with PC01 capturing length/width and subsequent PCs capturing curvature/rotation.
• Significant sex differences were found in PC01, PC02, and PC06 (p < 0.05), but no significant side differences were detected.
• Clustering analysis revealed two distinct morphological groups, showing poor agreement with traditional three-type classifications (Adjusted Rand Index ≈ 0).

Conclusions:

• Clavicular morphology demonstrates significant sex-dependent variability but is not dependent on the side (left vs. right).
• Traditional categorical classifications are insufficient for describing the continuous spectrum of clavicular anatomical diversity.
• SSM offers objective data to support personalized preoperative planning and enhance implant design for improved clavicle fracture fixation outcomes.