Microtrauma at the humeral medial epicondyle: Quantifying lacunar lesions to reconstruct activity patterns in past populations

OBJECTIVE: Lacunar lesions at the anterior medial collateral ligament (MCL) bundle attachment on the humeral medial epicondyle may represent partial avulsion fractures. This study developed and validated a quantitative approach to assess their morphology. MATERIALS: Two Neolithic samples were studied: Parisian Basin (France, N = 45) and Meuse Valley (Belgium, N = 25). METHODS: Lesions were extracted using a 3D protocol with ambient occlusion and curvature filters, then screened and analyzed using size, shape and surface metrics. Reproducibility was assessed using Lin's concordance correlation coefficient. RESULTS: The protocol was successfully validated with excellent intra-observer agreement. Lesions occurred exclusively on right humeri at the anterior MCL bundle footprint, while showing uniform shape but variable size, flattening and surface characteristics. CONCLUSIONS: The protocol provides an objective, reproducible method for lesion characterization and, when applied, revealed cortical-confined depths and surface areas smaller than the anterior MCL bundle footprint, suggesting specific fiber involvement. Right-side bias indicates a potential link with handedness, while morphological patterns align with clinical descriptions of proximal MCL partial avulsion fractures common in youth throwing athletes. SIGNIFICANCE: Findings support an activity-related etiology and demonstrate potential for reconstructing past behaviors from skeletal remains while complementing clinical studies on long-term injury outcomes. LIMITATIONS: Limitations include small sample size, reliance on absolute measurements, dependence on imaging resolution, and lack of direct clinical validation. SUGGESTIONS FOR FURTHER RESEARCH: Studies should apply this protocol to larger, diverse samples, confirm the clinical association, and adapt it to additional imaging modalities for broader archaeological and clinical applications.