title: An integrated approach for reconstructing a surface model of the proximal femur from sparse input data and a multi-resolution point distribution model: an in vitro study.
abstract: BACKGROUND
  Accurate reconstruction of a patient-specific surface model of the proximal femur from preoperatively or intraoperatively available sparse data plays an important role in planning and supporting various computer-assisted surgical procedures.
  
  
  METHODS
  In this paper, we present an integrated approach using a multi-resolution point distribution model (MR-PDM) to reconstruct a patient-specific surface model of the proximal femur from sparse input data, which may consist of sparse point data or a limited number of calibrated X-ray images. Depending on the modality of the input data, our approach chooses different PDMs. When 3D sparse points are used, which may be obtained intraoperatively via a pointer-based digitization or from a calibrated ultrasound, a fine level point distribution model (FL-PDM) is used in the reconstruction process. In contrast, when calibrated X-ray images are used, which may be obtained preoperatively or intraoperatively, a coarse level point distribution model (CL-PDM) will be used.
  
  
  RESULTS
  The present approach was verified on 31 femurs. Three different types of input data, i.e., sparse points, calibrated fluoroscopic images, and calibrated X-ray radiographs, were used in our experiments to reconstruct a surface model of the associated bone. Our experimental results demonstrate promising accuracy of the present approach.
  
  
  CONCLUSIONS
  A multi-resolution point distribution model facilitate the reconstruction of a patient-specific surface model of the proximal femur from sparse input data.
authors.affiliation: ARTORG Center for Biomedical Engineering Research, University of Bern, Stauffacherstrasse 78, 3014 Bern, Switzerland. guoyan.zheng@ieee.org
authors.forename: Guoyan
authors.initials: G
authors.lastname: Zheng
authors.forename: Steffen
authors.initials: S
authors.lastname: Schumann
authors.forename: Miguel A
authors.initials: MA
authors.lastname: González Ballester
mesh_terms: D005269:Femur / Q000033:anatomy & histology* / Q000601:surgery; D005270:Femur Head; D006801:Humans; D007091:Image Processing, Computer-Assisted / Q000295:instrumentation / Q000379:methods*; D008953:Models, Anatomic; D010363:Pattern Recognition, Automated / Q000379:methods; D011856:Radiographic Image Enhancement / Q000379:methods; D011857:Radiographic Image Interpretation, Computer-Assisted / Q000379:methods; D015203:Reproducibility of Results; D025321:Surgery, Computer-Assisted