Evaluation of the superior pubic ramus and supra acetabular corridors using statistical shape modelling

Area of Science:

• Orthopedic surgery
• Anatomy
• Medical imaging

Background:

• Osteoporotic pelvic fractures are increasing, necessitating careful surgical fixation.
• Accurate anatomical understanding is crucial for intramedullary screw placement to avoid joint perforation.
• Statistical shape modeling offers a method to analyze pelvic anatomy variability.

Purpose of the Study:

• To assess anatomical variability in the superior pubic ramus and supra-acetabular corridors.
• To determine corridor dimensions for safe screw placement in pelvic fracture fixation.
• To identify potential sex-specific differences in these critical anatomical regions.

Main Methods:

• Developed male and female statistical shape models from 59 forensic CT scans.
• Utilized principal component analysis (PCA) to capture pelvic shape variation.
• Modeled the longest/widest cylinders within the superior pubic ramus and supra-acetabular corridors for each principal component.

Main Results:

• The first 5 principal components explained 75% (male) and 79% (female) of pelvic variation.
• Female superior pubic ramus corridors were < 7.3 mm in 3 PCs, with a minimum width of 5.5 mm.
• All male superior pubic ramus and supra-acetabular corridors exceeded 7.3 mm across all PCs.

Conclusions:

• Female superior pubic ramus corridors may not accommodate 7.3 mm or 6.5 mm screws, influenced by pelvic morphology.
• The supra-acetabular corridor demonstrated sufficient width for a 7.3 mm screw in both sexes.
• These findings highlight the need for patient-specific anatomical assessment in pelvic fracture fixation.