PhD Defense: Simone Poncioni Advances Clinical Bone Strength Assessment Tools

In this thesis, Simone investigated the advancement of homogenized finite elements (hFE) modelling for second-generation high-resolution peripheral quantitative computed tomography (HR-pQCT) of distal skeletal sites using multi-stack imaging, with the aim of improving bone strength assessment for clinical applications. Fragility fractures pose a significant and growing public health burden, with an estimated €37 billion in fracture-related costs in Europe in 2010 and a fracture occurring worldwide every three seconds. Age-related bone loss is the main driver of increased susceptibility to fragility fractures among older adults.

Before HR-pQCT, bone strength was commonly assessed through the measurement of areal bone mineral density (aBMD) at the femoral neck using dual-energy X-ray absorptiometry (DXA). Although easily accessible, relatively inexpensive and straightforward to interpret, DXA’s low resolution and projective nature limited its diagnostic usefulness. HR-pQCT addressed these shortcomings by enabling compartmental densitometry, microstructural analyses, and finite element (FE)-based estimation of mechanical strength of the distal skeleton.

Simone further advanced the utility of HR-pQCT by developing and validating a smooth hexahedral meshing algorithm for homogenized finite element modelling of second-generation HR-pQCT scans, providing bone strength estimates in under 15 minutes and making it feasible for routine clinical use.

For his thesis, he applied the algorithm to a large Swiss cohort of 381 healthy adults aged 20 to 92, which produced the first age-, sex-, and site-specific normative reference data for multi-stack HR-pQCT, showing that bone strength and density parameters peaked in early adulthood and declined in rates that differed between sexes and skeletal sites. Simone was able to identify six size-independent parameters as most sensitive to age-related changes and additionally derived correction functions for densitometric parameters to reduce the systematic bias caused by soft tissue X-ray attenuation in longitudinal and cross-sectional studies.

Congratulations to Dr. Simone Poncioni on this incredible achievement and for advancing the clinical tools for accurate bone strength assessments!

Publications:

Poncioni, Simone; Pollaci, Alexia; Bracher, Stefan; Owusu, Silvia; Bosshardt, Dieter; Zysset, Philippe (n.d.). Densitometric correction for appendicular soft tissue artefacts measured by second-generation hr-pqct. b. In preparation.

Poncioni, Simone; Lüscher, Dominique; Indermaur, Michael; Frauchiger, Daniela Angelika; Meier, Christian; Zysset, Philippe; Lippuner, Kurt (2026). Sex- and site-specific reference data for size-invariant properties using multi-stack HR-pQCT. JBMR Plus, ziag077. Oxford University Press 10.1093/jbmrpl/ziag077

Poncioni, Simone; Lippuner, Kurt; Zysset, Philippe (2025). Advancing HR-pQCT-based homogenized FE models with smooth structured hexahedral meshes. Bone 193:117394. Elsevier 10.1016/j.bone.2025.117394

Vautrin Antoine; Wili, Patrik; Poncioni, Simone; Zysset, Philippe; Varga, Peter (2025). Comparative analysis of micro- and homogenized finite element simulations to predict the load-bearing capacity of trabecular bone screws. Journal of the Mechanical Behavior of Biomedical Materials 172:107168. Elsevier 10.1016/j.jmbbm.2025.107168