title: Semi-automated landmark-based 3D analysis reveals new morphometric characteristics in the trochlear dysplastic femur.
abstract: OBJECTIVE
  The authors hypothesise that the trochlear dysplastic distal femur is not only characterised by morphological changes to the trochlea. The purpose of this study is to describe the morphological characteristics of the trochlear dysplastic femur in and outside the trochlear region with a landmark-based 3D analysis.
  
  
  METHODS
  Arthro-CT scans of 20 trochlear dysplastic and 20 normal knees were used to generate 3D models including the cartilage. To rule out size differences, a set of landmarks were defined on the distal femur to isotropically scale the 3D models to a standard size. A predefined series of landmark-based reference planes were applied on the distal femur. With these landmarks and reference planes, a series of previously described characteristics associated with trochlear dysplasia as well as a series of morphometric characteristics were measured.
  
  
  RESULTS
  For the previously described characteristics, the analysis replicated highly significant differences between trochlear dysplastic and normal knees. Furthermore, the analysis showed that, when knee size is taken into account, the cut-off values of the trochlear bump and depth would be 1 mm larger in the largest knees compared to the smallest knees. For the morphometric characteristics, the analysis revealed that the trochlear dysplastic femur is also characterised by a 10% smaller intercondylar notch, 6-8% larger posterior condyles (lateral-medial) in the anteroposterior direction and a 6% larger medial condyle in the proximodistal direction compared to a normal femur.
  
  
  CONCLUSIONS
  This study shows that knee size is important in the application of absolute metric cut-off values and that the posterior femur also shows a significantly different morphology.
authors.affiliation: BioMech, Department of Mechanics, University College Ghent, Valentin Vaerwijckweg 1, 9000, Ghent, Belgium, mvhaver@hotmail.com.
authors.forename: Annemieke
authors.initials: A
authors.lastname: Van Haver
authors.forename: Karel
authors.initials: K
authors.lastname: De Roo
authors.forename: Matthieu
authors.initials: M
authors.lastname: De Beule
authors.forename: Sofie
authors.initials: S
authors.lastname: Van Cauter
authors.forename: Emmanuel
authors.initials: E
authors.lastname: Audenaert
authors.forename: Tom
authors.initials: T
authors.lastname: Claessens
authors.forename: Peter
authors.initials: P
authors.lastname: Verdonk
mesh_terms: D000293:Adolescent; D000328:Adult; D003198:Computer Simulation; D005260:Female; D005269:Femur / Q000002:abnormalities* / Q000000981:diagnostic imaging*; D006801:Humans; D021621:Imaging, Three-Dimensional; D007719:Knee Joint / Q000000981:diagnostic imaging*; D008297:Male; D012189:Retrospective Studies; D013977:Tibia / Q000000981:diagnostic imaging*; D014057:Tomography, X-Ray Computed; D055815:Young Adult