Asymmetry of the Intrinsic Scapholunate Articular Facets: A Cadaveric Morphometric Analysis.

BACKGROUND: Although the scapholunate ligamentous complex has gained significant importance in recent literature, the intrinsic articular interface itself remains insufficiently characterized. This study provides a detailed morphometric analysis of the scaphoid and lunate intrinsic facets to address this anatomical gap. METHODS: Twenty-six cadaveric wrists were evaluated. The scapholunate interval height was measured with a 0.05 mm caliper. After cutting the scapholunate interosseous ligament, the scaphoid and lunate facets were exposed for linear height measurements. Standardized photographs were taken alongside a millimeter ruler. Total facet area (TFA) was quantified using ImageJ/Fiji software by converting pixels to square millimeters through a calibration scale and multipoint marking for area measurement. Statistical analysis included the Shapiro-Wilk test for normality, followed by Wilcoxon signed-rank or Student t tests (P < .05). RESULTS: Significant dimensional asymmetry was identified, with the lunate TFA being larger than the scaphoid TFA in 96.2% of the specimens (P < .001). The lunate-to-scaphoid TFA ratio was 1.42. Quantitative positional asymmetry was confirmed, as the scapholunate interval height significantly exceeded the individual linear heights of both the scaphoid and lunate facets (P < .001). Qualitative analysis of the joint geometry revealed further asymmetries in shape and inclination: the scaphoid facet was smaller and beveled, while the lunate facet was larger and orthogonal. CONCLUSIONS: A consistent mismatch at the scapholunate interface was found. These data offer new anatomical insights that may enhance diagnosis and surgical planning for carpal reconstruction.