Predicting Osteoporotic Hip Fractures: In Vitro Study of 80 Femurs Using Three Imaging Methods and Finite Element Modeling -- The European Fracture Study (EFFECT) Pierre Pottecher 1, Klaus Engelke 2, Laure Duchemin 1, Oleg Museyko 2, Thomas Moser 1 David Mitton 1, Eric Vicaut 1, Judith Adams 3, Wafa Skalli 4, Jean-Denis Laredo 1, Valérie Bousson 1 1 Laboratoire de Radiologie Expérimentale, Paris, France et Assistance Publique-Hôpitaux de Paris 2 IMP, Erlangen, Germany 3 Clinical Radiology, The Royal Infirmary, and Imaging Science and Biomedical Engineering, University of Manchester, Angleterre 4 ENSAM, Paris, France

v BMD Geometry and bone architecture Quantity and bone mineral content Bone tissue distribution INTRODUCTION

MAIN OBJECTIVE Evaluate the performance of four techniques in predicting the failure load : -Three imaging modalities: Radiographs (XR), Dual- energy X-ray Absorptiometry (DXA), Quantitative Computed Tomography (QCT) with dedicated software MIAF-Femur -and one numerical analysis method: Finite Element Model (FEM)

SECONDARY OBJECTIVES Identify the geometric or densitometric parameters strongly related with the bone failure load Study the combination of these techniques in the prediction of bone failure load

MATERIAL and METHODS 40 pairs of excised femurs 24 women, 16 men Age of death: years [Mean: 81 years, SD: 12.1]

MATERIAL and METHODS 40 pairs of femurs XR DXAQCT Finite Element Models (FEM)

MATERIAL and METHODS 40 pairs of femurs XR DXAQCT Finite Element Models (FEM) Mechanical testing with bone fracture

MATERIAL and METHODS Hip Radiograph (XR) Position in medial rotation Focus to film distance: 120 cm Tube load: 45 kV, 4 mAs Table Prestige, GE

MATERIAL and METHODS Hip Radiograph (XR) Independently measuring of 16 XR variables potentially involved in bone strength (*) Two radiologists Mean of two measurements for each parameters (*) Glüer CC et al. J Bone Miner Res 1994; Bergot C et al. Osteoporos Int. 2002

MATERIAL and METHODS Dual-energy X-ray Absorptiometry (DXA) Position in medial rotation Immersion in a water bath to simulate (soft tissue density) Three areal BMD: Integral, Trochanter and Neck Appareil Hologic QDR 1000

MATERIAL and METHODS QCT + MIAF Femur 0 mg HA/ml 200 mg HA/ml Somatom Volume Zoom 4, Siemens Acquisition parameters 120 kV 225 mAs collimation: 4 x 1mm pitch: 1 Reconstructions parameters Slice thickness: 1 mm FOV: 150 mm Femoral head- Lesser trochanter Pixel size: mm Kernel: B40 Osteophantom, Siemens

MATERIAL and METHODS QCT+ MIAF Femur -Institute of Medical Physics, University of Erlangen, Erlangen, Germany -Semi automatic 3-D segmentation of the proximal femur - Neck Coordinate System (NCS) NCS

MATERIAL and METHODS QCT+ MIAF Femur 47 parameters - Six volumes of interest (VOI) Head, Neck, Neckbox, Trochanter, Trochanterslice et Intertrochanter - Densitometric parameters: BMD and Volume - Geometric parameters 4 cortical thicknesses, 18 moments of inertia (MOI)

MATERIAL and METHODS Finite Element Models (FEM) Numerical tool analysis Quantify bone behaviour subject to mechanical stresses Based on QCT analysis “ Mesh network” Generic reference Model (Duchemin et al.) Young’s modulus distribution Numerical Failure Load FL num

MATERIAL and METHODS Mechanical testing of bone rupture Two configurations: Stance and Lateral Experimental failure load (Newton), F EXP TROCHANTERIC LATERAL Configuration CERVICAL STANCE Configuration INSTROM 5500

RESULTS Stepwise regression XR STANCE Configuration r 2 =0.66 ITW MCFS LATERAL Configuration r 2 =0.63 ITW MCFS

RESULTS Stepwise regression DXA STANCE Configuration LATERAL Configuration r 2 =0.73 aBMD_Total r 2 =0.79 aBMD_Trochanter

RESULTS Stepwise regression QCT-MIAF Femur STANCE ConfigurationLATERAL Configuration r 2 =0.74 Neck Axial Moment of inertia (AMIM) vBMD InterTrochanter r 2 =0.83 TrochanterSlice axial moment of inertia vBMD Trochanter

RESULTS Linear regression Finite Element Model (FEM) STANCE ConfigurationLATERAL Configuration r 2 =0.87r 2 =0.82 F EXP =F O (FL NUM )

RESULTS Multiple regression XR + DXA STANCE ConfigurationLATERAL Configuration r 2 =0.82 ITW, MCFS aBMD_Tot r 2 =0.84 ITW, MCFS aBMD_Trochanter

RESULTS Multiple regression QCT + DXA STANCE ConfigurationLATERAL Configuration r 2 = 0.80r 2 =0.87

DISCUSSION and CONCLUSION Prediction of QCT and FEM ++ Densitometric parameters: aBMD and vBMD in Trochanter ++ Geometric parameters: - Cortical thickness (XR) - Moment of inertia (QCT) : elactic properties and BMD inhomogeneities Combination of geometric and densitometric parameters (QCT, XR + DXA)

DISCUSSION and CONCLUSION Limits of DXA Geometric parameters ++ Trochanteric region discriminating for bone strength : ITW (RX) + aBMD Trochanter (DXA) + vBMD Trochanter (QCT)

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