An exclusionary screening method based on 3D morphometric features to sort commingled atlases and axes

Area of Science:

• Forensic Anthropology
• Anatomical Identification
• 3D Imaging Techniques

Background:

• Accurate identification of skeletal remains is crucial in forensic contexts.
• Commingled remains pose challenges, especially when disarticulation occurs at specific joints like the atlantoaxial joint.
• No previous studies have utilized 3D methodologies for matching atlas and axis vertebrae.

Purpose of the Study:

• To investigate the potential of 3D-3D superimposition for re-associating atlas and axis vertebrae.
• To assess the congruency of articular surfaces using point-to-point distance (Root Mean Square, RMS).
• To determine the efficacy of this method in forensic commingled contexts.

Main Methods:

• Analyzed 41 documented skeletons (18 male, 23 female) and unpaired elements from 5 individuals.
• Utilized 3D-3D superimposition to compare articular surfaces of atlas and axis vertebrae.
• Calculated RMS distance values for both correct matches and mismatches between individuals.

Main Results:

• A total of 41 matches and 1851 mismatches were analyzed.
• No significant sex-related differences were found in RMS values for matches or mismatches.
• RMS values differed significantly between matches (0.41–0.77 mm) and mismatches (0.37–2.18 mm), with a threshold of 0.77 mm yielding 100% sensitivity and 41% specificity.

Conclusions:

• 3D-3D superimposition of atlanto-axial articular facets is a valuable screening method, not a definitive re-association technique.
• The method demonstrates high sensitivity for identifying correct bone pairings.
• Further research is needed to validate the 3D approach and explore its application to other skeletal joints.