Assessment of polyethylene wear in THA using Model-Based Roentgen Stereophotogrammetric analysis - an experimental phantom-model setup

2020 ◽  
Author(s):  
J Wu ◽  
R Forst ◽  
Y Hong ◽  
Z Kang ◽  
J Xu ◽  
...  
2005 ◽  
Vol 38 (11) ◽  
pp. 2330-2334 ◽  
Author(s):  
B.L. Kaptein ◽  
E.R. Valstar ◽  
B.C. Stoel ◽  
P.M. Rozing ◽  
J.H.C. Reiber

2021 ◽  
Author(s):  
Heiko Apel ◽  
Sergiy Vorogushyn ◽  
Mostafa Farrag ◽  
Nguyen Viet Dung ◽  
Melanie Karremann ◽  
...  

<p>Urban flash floods caused by heavy convective precipitation pose an increasing threat to communes world-wide due to the increasing intensity and frequency of convective precipitation caused by a warming atmosphere. Thus, flood risk management plans adapted to the current flood risk but also capable of managing future risks are of high importance. These plans necessarily need model based pluvial flood risk simulations. In an urban environment these simulations have to have a high spatial and temporal resolution in order to site-specific management solutions. Moreover, the effect of the sewer systems needs to be included to achieve realistic inundation simulations, but also to assess the effectiveness of the sewer system and its fitness to future changes in the pluvial hazard. The setup of these models, however, typically requires a large amount of input data, a high degree of modelling expertise, a long time for setting up the model setup and to finally run the simulations. Therefor most communes cannot perform this task.</p><p> In order to provide model-based pluvial urban flood hazard and finally risk assessments for a large number of communes, the model system RIM<em>urban</em> was developed. The core of the system consists of a simplified raster-based 2D hydraulic model simulating the urban surface inundation in high spatial resolution. The model is implemented on GPUs for massive parallelization. The specific urban hydrology is considered by a capacity-based simulation of the sewer system and infiltration on non-sealed surfaces, and flow routing around buildings. The model thus considers the specific urban hydrological features, but with simplified approaches. Due to these simplifications the model setup can be performed with comparatively low data requirements, which can be covered with open data in most cases. The core data required are a high-resolution DEM, a layer of showing the buildings, and a land use map.</p><p>The spatially distributed rainfall input can be derived local precipitation records, or from an analysis of weather radar records of heavy precipitation events. A catalogue of heavy rain storms all over Germany is derived based on radar observations of the past 19 years. This catalogue serves as input for pluvial risk simulations for individual communes in Germany, as well as a catalogue of possible extreme events for the current climate. Future changes in these extreme events will be estimated based on regional climate simulations of a ΔT (1.5°C, 2°C) warmer world.</p><p>RIM<em>urban</em> simulates the urban inundation caused by these events, as well as the stress on the sewer system. Based on the inundation maps the damage to residential buildings will be estimated and further developed to a pluvial urban flood risk assessment. Because of the comparatively simple model structure and low data demand, the model setup can be easily automatized and transferred to most small to medium sized communes in Europe and even beyond, if the damage estimation is modified. RIM<em>urban</em> is thus seen as a generally appölicable screening tool for urban pluvial flood risk and a starting point for adapted risk management plans.</p>


Materials ◽  
2020 ◽  
Vol 13 (7) ◽  
pp. 1543 ◽  
Author(s):  
Jing Xu ◽  
Robert Sonntag ◽  
J. Philippe Kretzer ◽  
Dominic Taylor ◽  
Raimund Forst ◽  
...  

Model-based Roentgen stereophotogrammetric analysis (RSA) using elementary geometrical shape (EGS) models allows migration measurement of implants without the necessity of additional attached implant markers. The aims of this study were: (i) to assess the possibility of measuring potential head–taper movement in THA in vivo using model-based RSA and (ii) to prove the validity of measured head–taper migration data in vitro and in vivo. From a previous RSA study with a 10 years follow-up, retrospectively for n = 45 patients head–taper migration was calculated as the relative migration between femoral ball head and taper of the femoral stem using model-based RSA. A head–taper migration of 0.026 mm/year can be detected with available RSA technology. In vitro validation showed a total migration of 268 ± 11 µm along the taper axis in a similar range to what has been reported using the RSA method. In vivo, a proof for interchangeable applicability of model-based RSA (EGS) and standard marker-based RSA methods was indicated by a significant deviation within the migration result after 12-month follow-up for all translation measurements, which was significantly correlated to the measured head–taper migration (r from 0.40 to 0.67; p < 0.05). The results identified that model-based RSA (EGS) could be used to detect head–taper migration in vivo and the measured movement could be validated in vitro and in vivo as well. Those findings supported the possibility of applying RSA for helping evaluate the head–taper corrosion related failure (trunnionosis).


2020 ◽  
Vol 10 (23) ◽  
pp. 8507
Author(s):  
Jing Xu ◽  
Han Cao ◽  
Stefan Sesselmann ◽  
Dominic Taylor ◽  
Raimund Forst ◽  
...  

Elementary Geometrical Shape (EGS) models present an alternative approach to detect in vivo migration of total hip arthroplasty using model-based Roentgen Stereophotogrammetric Analysis (mbRSA). However, its applicability for an irregular-shaped femoral stem and the reliability of this mbRSA approach has not been proven so far. The aim of this study is to assess the effect of multi-rater and an anatomically shaped femoral stem design onto resulting implant to bone migration results. The retrospective analysis included 18 clinical cases of anatomically shaped stem with 10-year RSA follow-ups. Three raters repeatedly measured all RSA follow-ups for evaluating the rater equivalence and intra-rater reliability. The results proved the equivalence between different raters for mbRSA using EGS models (mbRSA-EGS), hence it simplified the investigation of rater reliability to intra-rater reliability. In all in-plane migration measurements, mbRSA-EGS shows good intra-rater reliability and small intra-rater variability (translation: <0.15 mm; rotation: <0.18 deg). However, the reliability is worse in the out-of-plane measurements, especially the cranial-caudal rotation (intra-rater variability: 0.99–1.81 deg). Overall, mbRSA-EGS can be an alternative approach next to surface models while the in-plane migration of femoral stem (e.g., the implant subsidence for loosening prediction) have more research interested than other directions.


2010 ◽  
Vol 35 (6) ◽  
pp. 480-485 ◽  
Author(s):  
T. B. Hansen ◽  
K. Larsen ◽  
L. Bjergelund ◽  
M. Stilling

Both marker-based roentgen stereophotogrammetric analysis (RSA) and model-based RSA have been helpful evaluation tools in hip and knee arthroplasty. The purpose of this study was to test both model-based and marker-based RSA in the evaluation of total joint prostheses of the trapeziometacarpal joint. In a phantom study, the precision of marker-based RSA was tested with a cemented polyethylene cup and compared with the precision of model-based RSA in an uncemented Elektra screw cup. The precision of model-based RSA of the metacarpal stem was tested using an uncemented Elektra metacarpal stem. In a clinical study 11 patients had double stereo radiographs followed by RSA analysis. The precision of translation in both marker-based and model-based RSA was sufficient for clinical use, but rotation cannot be estimated with sufficient precision.


2012 ◽  
Vol 1 (8) ◽  
pp. 180-191 ◽  
Author(s):  
M. Stilling ◽  
S. Kold ◽  
S. de Raedt ◽  
N. T. Andersen ◽  
O. Rahbek ◽  
...  

2012 ◽  
Vol 15 (12) ◽  
pp. 1347-1357 ◽  
Author(s):  
Ci-Bin Syu ◽  
Shang-Chih Lin ◽  
Chung-Yi Huang ◽  
Jiing-Yih Lai ◽  
Kao-Shang Shih ◽  
...  

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