Virtual 3D landmark palpation in clubfoot: feasibility of an innovative standardized morphometric protocol. A preliminary study

Abstract

BACKGROUND: Reliable morphological assessment remains a clinical challenge in congenital clubfoot management, as current clinical scoring systems fail to capture the complex three-dimensional anatomy required for precise evaluation and treatment planning. Virtual palpation of anatomical landmarks offers a standardized, objective approach to define bony axes, but requires rigorous validation to become clinically applicable. METHODS: 3D models (dried clubfoot and normal foot) were reconstructed from segmented CT scan datasets using image segmentation. For reproducibility purpose, thirty-two anatomical landmarks covering major tarsal bones were independently identified by three operators on three separate occasions using an in-house software lhpFusionBox (Laboratory of Biomechanics and Bioengineering, Université libre de Bruxelles, Brussels, Belgium). Key measurements are proposed to quantify foot bone orientations including root mean square errors (RMS), Bland-Altman plots, and stability indices assessed reproducibility. A complementary analysis evaluated clinical applicability through bony axis measurement and three-dimensional deformity quantification. RESULTS: Intra-operator reproducibility achieved mean RMS of 1.07 mm (90.6% < 2 mm) and inter-operator reproducibility of 1.28 mm (84.03% < 2 mm)-both within clinically acceptable thresholds. Mean biases were negligible (- 0.5 to + 0.5 mm) with narrow limits of agreement (± 6-7 mm). Distal lateral and dorsal landmarks demonstrated superior stability (< 0.6 mm). The protocol successfully identified clinically significant angular deviations between clubfoot and normal foot axes, demonstrating its utility for objective morphometric assessment and treatment monitoring. CONCLUSION: This standardized 3D landmark-based protocol achieves significative intra- and inter-observer reliability with proven geometric validity, meeting critical requirements for clinical adoption. It provides orthopedic clinicians with an objective, reproducible tool for clubfoot assessment, bridging the gap between subjective clinical evaluation and quantitative morphometric analysis. This advancement enables more precise treatment planning and standardized monitoring of deformity correction.