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    <completedYear/>
    <publishedYear>2015</publishedYear>
    <thesisYearAccepted/>
    <language>eng</language>
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    <title language="eng">Assessing the relative positioning of an osteosynthesis plate to the patient-specific femoral shape from plain 2D radiographs</title>
    <abstract language="eng">We  present  a   novel  method  to  derive  the surface distance of an osteosynthesis  plate w.r.t. the patient­specific  surface  of  the  distal  femur  based  on  2D  X­ray  images.  Our  goal  is  to  study from  clinical  data,  how  the  plate­to­bone  distance  affects  bone  healing.  The  patient­specific 3D  shape  of the femur is, however, seldom recorded for cases of femoral  osteosynthesis since this  typically  requires  Computed  Tomography  (CT),  which  comes  at  high  cost  and  radiation dose.  Our method instead utilizes two postoperative X­ray images to derive the femoral shape and  thus  can  be  applied  on  radiographs  that  are  taken  in  clinical  routine  for  follow­up.  First, the  implant  geometry  is  used  as  a  calibration  object  to  relate  the  implant  and  the  individual X­ray  images  spatially  in  a  virtual  X­ray  setup.  In  a  second step, the patient­specific femoral shape  and  pose  are  reconstructed  in  the  virtual  setup  by  fitting  a deformable statistical shape and  intensity  model  (SSIM)  to  the  images.  The  relative  positioning  between  femur  and implant  is  then  assessed  in  terms  of  displacement  between  the  reconstructed  3D shape of the femur  and  the  plate.  A   preliminary  evaluation  based  on  4  cadaver  datasets  shows  that  the method  derives  the  plate­to­bone  distance  with  a  mean absolute error of less than 1mm and a maximum  error  of  4.7  mm  compared  to  ground  truth  from  CT. We believe that the approach presented  in  this  paper  constitutes  a  meaningful  tool  to  elucidate  the  effect  of  implant positioning on fracture healing.</abstract>
    <parentTitle language="eng">Proceedings of the 15th Annual Meeting of CAOS-International (CAOS)</parentTitle>
    <enrichment key="PeerReviewed">yes</enrichment>
    <enrichment key="PreprintUrn">urn:nbn:de:0297-zib-54268</enrichment>
    <author>Moritz Ehlke</author>
    <submitter>Moritz Ehlke</submitter>
    <author>Mark Heyland</author>
    <author>Sven Märdian</author>
    <author>Georg Duda</author>
    <author>Stefan Zachow</author>
    <subject>
      <language>eng</language>
      <type>uncontrolled</type>
      <value>3d-­reconstruction from 2d X­rays</value>
    </subject>
    <subject>
      <language>eng</language>
      <type>uncontrolled</type>
      <value>statistical shape and intensity models</value>
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    <subject>
      <language>eng</language>
      <type>uncontrolled</type>
      <value>fracture fixation of the distal femur</value>
    </subject>
    <subject>
      <language>eng</language>
      <type>uncontrolled</type>
      <value>pose estimation</value>
    </subject>
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    <collection role="institutes" number="medplan">Therapy Planning</collection>
    <collection role="persons" number="ehlke">Ehlke, Moritz</collection>
    <collection role="persons" number="zachow">Zachow, Stefan</collection>
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  <doc>
    <id>5426</id>
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    <language>eng</language>
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    <publishedDate>2015-01-04</publishedDate>
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    <title language="eng">Assessing the Relative Positioning of an Osteosynthesis Plate to the Patient-Specific Femoral Shape from Plain 2D Radiographs</title>
    <abstract language="eng">We  present  a   novel  method  to  derive  the surface distance of an osteosynthesis  plate w.r.t. the patient­specific  surface  of  the  distal  femur  based  on  2D  X­ray  images.  Our  goal  is  to  study from  clinical  data,  how  the  plate­to­bone  distance  affects  bone  healing.  The  patient­specific 3D  shape  of the femur is, however, seldom recorded for cases of femoral  osteosynthesis since this  typically  requires  Computed  Tomography  (CT),  which  comes  at  high  cost  and  radiation dose.  Our method instead utilizes two postoperative X­ray images to derive the femoral shape and  thus  can  be  applied  on  radiographs  that  are  taken  in  clinical  routine  for  follow­up.  First, the  implant  geometry  is  used  as  a  calibration  object  to  relate  the  implant  and  the  individual X­ray  images  spatially  in  a  virtual  X­ray  setup.  In  a  second step, the patient­specific femoral shape  and  pose  are reconstructed  in  the  virtual  setup  by  fitting  a deformable statistical shape and  intensity  model  (SSIM)  to  the  images.  The  relative  positioning  between  femur  and implant  is  then  assessed  in  terms  of  displacement  between  the  reconstructed  3D shape of the femur  and  the  plate.  A   preliminary  evaluation  based  on  4  cadaver  datasets  shows  that  the method  derives  the  plate­to­bone  distance  with  a  mean absolute error of less than 1mm and a maximum  error  of  4.7  mm  compared  to  ground  truth  from  CT. We believe that the approach presented  in  this  paper  constitutes  a  meaningful  tool  to  elucidate  the  effect  of  implant positioning on fracture healing.</abstract>
    <identifier type="issn">1438-0064</identifier>
    <identifier type="urn">urn:nbn:de:0297-zib-54268</identifier>
    <enrichment key="SourceTitle">Appeared in: Proceedings of the 15th Annual Meeting of CAOS-International (CAOS)</enrichment>
    <author>Moritz Ehlke</author>
    <submitter>Moritz Ehlke</submitter>
    <author>Mark Heyland</author>
    <author>Sven Märdian</author>
    <author>Georg Duda</author>
    <author>Stefan Zachow</author>
    <series>
      <title>ZIB-Report</title>
      <number>15-21</number>
    </series>
    <subject>
      <language>eng</language>
      <type>uncontrolled</type>
      <value>3d-­reconstruction from 2d X­rays</value>
    </subject>
    <subject>
      <language>eng</language>
      <type>uncontrolled</type>
      <value>statistical shape and intensity models</value>
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    <subject>
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      <value>fracture fixation of the distal femur</value>
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    <subject>
      <language>eng</language>
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      <value>pose estimation</value>
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    <file>https://opus4.kobv.de/opus4-zib/files/5426/ZIB-Report-15-21.pdf</file>
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