A method to reconstruct patient-specific proximal femur surface models from planar pre-operative radiographs

2010 ◽  
Vol 32 (10) ◽  
pp. 1180-1188 ◽  
Author(s):  
P.E. Galibarov ◽  
P.J. Prendergast ◽  
A.B. Lennon
Keyword(s):  
Proximal Femur ◽  
Patient Specific ◽  
Surface Models

scholarly journals Constructing a Human Atrial Fibre Atlas

2020 ◽  
Vol 49 (1) ◽  
pp. 233-250 ◽  
Author(s):  
Caroline H. Roney ◽  
Rokas Bendikas ◽  
Farhad Pashakhanloo ◽  
Cesare Corrado ◽  
Edward J. Vigmond ◽  
...  
Keyword(s):  
Coordinate System ◽  
Pulmonary Veins ◽  
Vena Cava ◽  
The Other ◽  
Patient Specific ◽  
Activation Time ◽  
Density Maps ◽  
Surface Models ◽  
Average Fibre ◽  
Density Map

AbstractAtrial anisotropy affects electrical propagation patterns, anchor locations of atrial reentrant drivers, and atrial mechanics. However, patient-specific atrial fibre fields and anisotropy measurements are not currently available, and consequently assigning fibre fields to atrial models is challenging. We aimed to construct an atrial fibre atlas from a high-resolution DTMRI dataset that optimally reproduces electrophysiology simulation predictions corresponding to patient-specific fibre fields, and to develop a methodology for automatically assigning fibres to patient-specific anatomies. We extended an atrial coordinate system to map the pulmonary veins, vena cava and appendages to standardised positions in the coordinate system corresponding to the average location across the anatomies. We then expressed each fibre field in this atrial coordinate system and calculated an average fibre field. To assess the effects of fibre field on patient-specific modelling predictions, we calculated paced activation time maps and electrical driver locations during AF. In total, 756 activation time maps were calculated (7 anatomies with 9 fibre maps and 2 pacing locations, for the endocardial, epicardial and bilayer surface models of the LA and RA). Patient-specific fibre fields had a relatively small effect on average paced activation maps (range of mean local activation time difference for LA fields: 2.67–3.60 ms, and for RA fields: 2.29–3.44 ms), but had a larger effect on maximum LAT differences (range for LA 12.7–16.6%; range for RA 11.9–15.0%). A total of 126 phase singularity density maps were calculated (7 anatomies with 9 fibre maps for the LA and RA bilayer models). The fibre field corresponding to anatomy 1 had the highest median PS density map correlation coefficient for LA bilayer simulations (0.44 compared to the other correlations, ranging from 0.14 to 0.39), while the average fibre field had the highest correlation for the RA bilayer simulations (0.61 compared to the other correlations, ranging from 0.37 to 0.56). For sinus rhythm simulations, average activation time is robust to fibre field direction; however, maximum differences can still be significant. Patient specific fibres are more important for arrhythmia simulations, particularly in the left atrium. We propose using the fibre field corresponding to DTMRI dataset 1 for LA simulations, and the average fibre field for RA simulations as these optimally predicted arrhythmia properties.

Osteoporotic Hip Fracture Prediction: Is T-Score-Based Criterion Enough? A Hip Structural Analysis-Based Model

2018 ◽  
Vol 140 (11) ◽  
Author(s):  
Alessandra Aldieri ◽  
Mara Terzini ◽  
Giangiacomo Osella ◽  
Adriano M. Priola ◽  
Alberto Angeli ◽  
...  
Keyword(s):  
Hip Fracture ◽  
Structural Analysis ◽  
Fracture Risk ◽  
Proximal Femur ◽  
Patient Specific ◽  
Multivariate Linear Regression Analysis ◽  
Hip Structural Analysis ◽  
Mineral Density ◽  
Neck Shaft Angle ◽  
Adopted Model

At present, the current gold-standard for osteoporosis diagnosis is based on bone mineral density (BMD) measurement, which, however, has been demonstrated to poorly estimate fracture risk. Further parameters in the hands of the clinicians are represented by the hip structural analysis (HSA) variables, which include geometric information of the proximal femur cross section. The purpose of this study was to investigate the suitability of HSA parameters as additional hip fracture risk predictors. With this aim, twenty-eight three-dimensional patient-specific models of the proximal femur were built from computed tomography (CT) images and a sideways fall condition was reproduced by finite element (FE) analyses. A tensile or compressive predominance based on minimum and maximum principal strains was determined at each volume element and a risk factor (RF) was calculated. The power of HSA variables combinations to predict the maximum superficial RF values was assessed by multivariate linear regression analysis. The optimal regression model, identified through the Akaike information criterion (AIC), only comprises two variables: the buckling ratio (BR) and the neck-shaft angle (NSA). In order to validate the study, the model was tested on two additional patients who suffered a hip fracture after a fall. The results classified the patients in the high risk level, confirming the prediction power of the adopted model.

A CT-Based High-Order Finite Element Analysis of the Human Proximal Femur Compared to In-vitro Experiments

2006 ◽  
Vol 129 (3) ◽  
pp. 297-309 ◽  
Author(s):  
Zohar Yosibash ◽  
Royi Padan ◽  
Leo Joskowicz ◽  
Charles Milgrom
Keyword(s):  
Finite Element ◽  
Proximal Femur ◽  
Mechanical Response ◽  
Clinical Importance ◽  
High Order ◽  
Patient Specific ◽  
In Vitro Experiments ◽  
Element Analysis ◽  
Bone Response

The prediction of patient-specific proximal femur mechanical response to various load conditions is of major clinical importance in orthopaedics. This paper presents a novel, empirically validated high-order finite element method (FEM) for simulating the bone response to loads. A model of the bone geometry was constructed from a quantitative computerized tomography (QCT) scan using smooth surfaces for both the cortical and trabecular regions. Inhomogeneous isotropic elastic properties were assigned to the finite element model using distinct continuous spatial fields for each region. The Young’s modulus was represented as a continuous function computed by a least mean squares method. p-FEMs were used to bound the simulation numerical error and to quantify the modeling assumptions. We validated the FE results with in-vitro experiments on a fresh-frozen femur loaded by a quasi-static force of up to 1500N at four different angles. We measured the vertical displacement and strains at various locations and investigated the sensitivity of the simulation. Good agreement was found for the displacements, and a fair agreement found in the measured strain in some of the locations. The presented study is a first step toward a reliable p-FEM simulation of human femurs based on QCT data for clinical computer aided decision making.

3D patient-specific finite element models of the proximal femur based on DXA towards the classification of fracture and non-fracture cases

Bone ◽  
2019 ◽  
Vol 121 ◽  
pp. 89-99 ◽  
Author(s):  
Carlos Ruiz Wills ◽  
Andy Luis Olivares ◽  
Simone Tassani ◽  
Mario Ceresa ◽  
Veronika Zimmer ◽  
...  
Keyword(s):  
Finite Element ◽  
Proximal Femur ◽  
Patient Specific ◽  
Finite Element Models

scholarly journals Correction of complex three-dimensional deformities at the proximal femur using indirect reduction with angle blade plate and patient-specific instruments: a technical note

2021 ◽  
Vol 16 (1) ◽  
Author(s):  
Lukas Jud ◽  
Lazaros Vlachopoulos ◽  
Karl Grob
Keyword(s):  
Proximal Femur ◽  
Three Dimensional ◽  
Orthopedic Procedures ◽  
Patient Specific ◽  
Indirect Reduction ◽  
Subvastus Approach ◽  
Blade Plate ◽  
Patient Specific Instruments ◽  
Angle Blade ◽  
Angle Blade Plate

Abstract Background Corrective osteotomies for complex proximal femoral deformities can be challenging; wherefore, subsidies in preoperative planning and during surgical procedures are considered helpful. Three-dimensional (3D) planning and patient-specific instruments (PSI) are already established in different orthopedic procedures. This study gives an overview on this technique at the proximal femur and proposes a new indirect reduction technique using an angle blade plate. Methods Using computed tomography (CT) data, 3D models are generated serving for the preoperative 3D planning. Different guides are used for registration of the planning to the intraoperative situation and to perform the desired osteotomies with the following reduction task. A new valuable tool to perform the correction is the use of a combined osteotomy and implant-positioning guide, with indirect deformity reduction over an angle blade plate. Results An overview of the advantages of 3D planning and the use of PSI in complex corrective osteotomies at the proximal femur is provided. Furthermore, a new technique with indirect deformity reduction over an angle blade plate is introduced. Conclusion Using 3D planning and PSI for complex corrective osteotomies at the proximal femur can be a useful tool in understanding the individual deformity and performing the aimed deformity reduction. The indirect reduction over the implant is a simple and valuable tool in achieving the desired correction, and concurrently, surgical exposure can be limited to a subvastus approach.

scholarly journals Biomechanical Analysis of Fibular Graft Techniques for Nontraumatic Osteonecrosis of Femoral Head: A Finite Element Analysis

2020 ◽  
Author(s):  
Jian Xu ◽  
Shi Zhan ◽  
Ming Ling ◽  
Dajun Jiang ◽  
Hai Hu ◽  
...  
Keyword(s):  
Finite Element ◽  
Femoral Head ◽  
Healthy Subject ◽  
Proximal Femur ◽  
Weight Bearing ◽  
Biomechanical Properties ◽  
Patient Specific ◽  
Structural Stiffness ◽  
Osteonecrosis Of Femoral Head ◽  
Weight Bearing Area

Abstract Background: Free vascularized fibula graft (FVFG) technique has achieved the most consistent successful therapeutic effect on young patients diagnosed as nontraumatic osteonecrosis of femoral head (NONFH), of which the Core Track Technique (CTT) has been the most commonly used. As an alternative to CTT, the modified Light Bulb Technique (LBT) was reported to have a higher success rate. However, its biomechanical characters have been poorly understood. This study aimed to investigate the biomechanical properties of modified LBT in treating NONFH by comparing with CTT.Methods: Two types (C1 and C2) of NONFH finite element models were established from a healthy subject according to the Japanese Investigation Committee (JIC) classification, and CTT and LBT procedures were simulated in each type of the models. The average Von Mises stresses and stiffness of the proximal femur were calculated by applying 250% body weight loading on femoral head to simulate walking condition. In addition, two patient-specific models were built and simulated under the same boundary condition for the further validation of LBT.Results: In the healthy subject-derived models, both LBT and CTT resulted in reduced stresses in the weight-bearing area, central femoral head, femoral neck, and trochanteric and subtrochanteric regions, and increased structural stiffness after surgery. In the weight-bearing area, CTT reduced more stresses than LBT (36.19% vs 31.45%) for Type C1, while less reduction (23.63% vs 26.76%) for Type C2. In patient-specific models, stiffness and stresses of before and after surgery were also increased and reduced respectively, which is consistent with healthy subject-derived models.Conclusion: LBT and CTT have different biomechanical performance on different JIC type of NONFH. In terms of preventing the collapse of femoral head, LBT may be more effective for JIC Type C2, which could alternatively be chosen, while for JIC Type C1, CTT is still a better choice. Both techniques can improve biomechanical properties of NONFH with patients’ proximal femur stress reduced and structural stiffness enhanced.

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