A Standardized, Three-Dimensional Cropping Protocol for Analyzing the Medial Epicondyle of the Humerus

Area of Science:

• Paleoanthropology
• Bioarchaeology
• Human Anatomy

Background:

• The medial epicondyle of the humerus is crucial for understanding activity-related skeletal changes.
• Characterizing these skeletal changes on the humerus presents significant challenges.
• Standardized analysis methods are needed for reliable investigation.

Purpose of the Study:

• To introduce a semi-automated cropping protocol for standardizing the analysis of the medial epicondyle and its entheseal surfaces.
• To assess the repeatability and reproducibility of the proposed protocol.

Main Methods:

• A landmark-based cropping protocol was developed using 3DSlicer.
• Mesh resolution and orientation were standardized prior to protocol application.
• Repeatability and reproducibility were evaluated on 20 humeri by measuring landmark placement precision and cropped surface area.

Main Results:

• The protocol successfully isolated the entire entheseal region.
• Intra-observer landmark placement precision was high (mostly <1mm), with inter-observer variability ranging from <1mm to 4mm.
• High reliability was demonstrated with distance-based Intraclass Correlation Coefficients (dICC) > 0.99 and other correlation coefficients > 0.94. Mean surface area errors were generally below 5%.

Conclusions:

• The developed protocol provides a standardized and holistic approach for studying entheseal changes at the medial epicondyle, accommodating morphological variations.
• The method exhibits low observer error, comparable to the lowest in existing studies.
• This tool aids in reconstructing physical activity, pathological conditions, and human evolutionary adaptation through entheseal surface analysis.