Sex and Laterality Differences in Medullary Humerus Morphology.

Area of Science:

• Anatomy
• Biomedical Engineering
• Orthopedic Surgery

Background:

• Percutaneous osseointegrated (OI) prosthetic limb attachment is a promising solution for transhumeral amputees.
• Understanding the morphology of the humerus is essential for designing effective upper extremity OI systems and for megaprosthetic reconstruction of the distal humerus.

Purpose of the Study:

• To quantify sex and laterality differences in humerus morphology, focusing on the diaphysis.
• To provide data that can inform the design of endoprosthetic stems for percutaneous OI implants and distal humerus replacements.

Main Methods:

• Utilized CT data to create 3D surface reconstructions of 58 pairs of cadaveric humeri (43 male, 15 female).
• Collected measurements of periosteal and medullary morphology relative to an anatomic coordinate system.
• Analyzed sex and laterality differences in biomechanical length, head radius, retroversion, canal orientation, medullary diameter, and cortical thickness.

Main Results:

• Observed significant sex and laterality differences in biomechanical length, head radius, and retroversion.
• Identified sex-based differences in proximal medullary canal diameter and endosteal cortex divergence.
• Found laterality differences in medullary diameters and sex-based differences in canal aspect ratios and cortical thickness.

Conclusions:

• Human humeral diaphysis morphology exhibits distinct sex and laterality variations.
• These morphological differences are position-dependent along the diaphysis.
• Accurate understanding of humeral morphology is critical for successful design and implantation of osseointegrated prosthetics and endoprosthetic stems.