title: A statistical shape model of trochlear dysplasia of the knee.
abstract: BACKGROUND
  Trochlear dysplasia is known as the primary predisposing factor for patellar dislocation. Current methods to describe trochlear dysplasia are mainly qualitative or based on a limited number of discrete measurements. The purpose of this study is to apply statistical shape analysis to take the full geometrical complexity of trochlear dysplasia into account.
  
  
  METHODS
  Statistical shape analysis was applied to 20 normal and 20 trochlear dysplastic distal femur models, including the cartilage.
  
  
  RESULTS
  This study showed that the trochlea was anteriorized, proximalized and lateralized and that the mediolateral width and the notch width were decreased in the trochlear dysplastic femur compared to the normal femur. The first three principal components of the trochlear dysplastic femurs, accounting for 79.7% of the total variation, were size, sulcus angle and notch width. Automated classification of the trochlear dysplastic and normal femora achieved a sensitivity of 85% and a specificity of 95%.
  
  
  CONCLUSIONS
  This study shows that shape analysis is an outstanding method to visualise the location and magnitude of shape abnormalities. Improvement of automated classification and subtyping within the trochlear dysplastic group are expected when larger training sets are used.
  
  
  CONCLUSIONS
  Classification of trochlear dysplasia, especially borderline cases may be facilitated by automated classification. Furthermore, the identification of a decreased notch width in association with an increased sulcus angle can also contribute to the diagnosis of trochlear dysplasia.
authors.affiliation: Department of Mechanics, BioMech, University College Ghent, Valentin Vaerwijckweg 1, 9000 Ghent, Belgium; Department of Production and Construction, Ghent University, 9052 Zwijnaarde, Belgium; Monica Orthopaedic Research Institute (MORE Institute), 2100 Antwerp, Belgium. Electronic address: mvhaver@hotmail.com.
authors.forename: A
authors.initials: A
authors.lastname: Van Haver
authors.affiliation: Department of Physical medicine and Orthopaedic Surgery, Ghent University, De Pintelaan 185, 9000 Ghent, Belgium.
authors.forename: P
authors.initials: P
authors.lastname: Mahieu
authors.affiliation: Department of Mechanics, BioMech, University College Ghent, Valentin Vaerwijckweg 1, 9000 Ghent, Belgium; Department of Civil Engineering, IBiTech - bioMMeda, Ghent University, De Pintelaan 185, 9000 Ghent, Belgium.
authors.forename: T
authors.initials: T
authors.lastname: Claessens
authors.affiliation: Department of Computer Science, University of Southern California, USA.
authors.forename: H
authors.initials: H
authors.lastname: Li
authors.affiliation: Department of Physical medicine and Orthopaedic Surgery, Ghent University, De Pintelaan 185, 9000 Ghent, Belgium.
authors.forename: C
authors.initials: C
authors.lastname: Pattyn
authors.affiliation: Department of Physical medicine and Orthopaedic Surgery, Ghent University, De Pintelaan 185, 9000 Ghent, Belgium; Monica Hospital, 2100 Antwerp, Belgium.
authors.forename: P
authors.initials: P
authors.lastname: Verdonk
authors.affiliation: Department of Physical medicine and Orthopaedic Surgery, Ghent University, De Pintelaan 185, 9000 Ghent, Belgium.
authors.forename: E A
authors.initials: EA
authors.lastname: Audenaert
mesh_terms: D000293:Adolescent; D000328:Adult; D002358:Cartilage, Articular / Q000000981:diagnostic imaging; D016022:Case-Control Studies; D016002:Discriminant Analysis; D005260:Female; D005269:Femur / Q000002:abnormalities* / Q000000981:diagnostic imaging*; D006801:Humans; D007091:Image Processing, Computer-Assisted; D021621:Imaging, Three-Dimensional; D008297:Male; D008875:Middle Aged; D015233:Models, Statistical; D061330:Multidetector Computed Tomography; D057071:Patellofemoral Joint / Q000002:abnormalities / Q000000981:diagnostic imaging; D025341:Principal Component Analysis; D055815:Young Adult
keywords: Morphology; Principal component analysis; Statistical shape analysis; Trochlear dysplasia