title: Mapping of the femoral trochlea in a newborn population: an ultrasonographic study.
abstract: BACKGROUND
  The anatomy of the femoral trochlea is of vital importance to the stability of the patellofemoral joint. Knowing the characteristics of the femoral trochlea in newborns might prove useful when considering the predisposing factors to patellar instability.
  
  
  OBJECTIVE
  To define the normal anatomy and the natural variances of the femoral trochlea in a newborn population as well as evaluation of ultrasonography as a method of imaging.
  
  
  METHODS
  The femoral trochlea of both knees of 174 newborns (82 girls and 92 boys) was examined using ultrasonography within 3 days after birth. For evaluation of the repeatability of the method, a separate population of 40 newborns was examined by two examiners.
  
  
  RESULTS
  The sulcus angle (SA) and Trochlear Index (TI) proved to be the most reliable and reproducible parameters. The overall mean SA was 148° (SD 5.6). An angle of more than 159° was defined as dysplastic, and 17 of the knees were categorized in this group. The overall mean TI was 2.21 (SD 0.05). A value of less than 2.11 was defined as dysplastic and 11 of the newborns fell into this category.
  
  
  CONCLUSIONS
  As a method of visualizing the newborn femoral trochlea and the position of the patella, ultrasonography is a reliable tool and might be of vital importance. In a further perspective, knowledge of the anatomy of a normal versus a dysplastic newborn trochlea renders it possible to study the predisposing factors to patellar instability and methods of treatment. Our results indicate that dysplasia of the femoral trochlea may be congenital.
authors.affiliation: Department of Orthopaedic Surgery, University Hospital of Trondheim, Trondheim, Norway christian.oye@ntnu.no.
authors.forename: Christian R
authors.initials: CR
authors.lastname: Øye
authors.affiliation: Department of Orthopaedic Surgery, University Hospital of Trondheim, Trondheim, Norway.
authors.forename: Ketil J
authors.initials: KJ
authors.lastname: Holen
authors.affiliation: Department of Orthopaedic Surgery, University Hospital of Trondheim, Trondheim, Norway.
authors.forename: Olav A
authors.initials: OA
authors.lastname: Foss
mesh_terms: D005260:Female; D005269:Femur / Q000002:abnormalities* / Q000000981:diagnostic imaging*; D006801:Humans; D015994:Incidence; D007231:Infant, Newborn; D007593:Joint Instability / Q000151:congenital* / Q000000981:diagnostic imaging* / Q000453:epidemiology; D007719:Knee Joint / Q000002:abnormalities* / Q000000981:diagnostic imaging*; D008297:Male; D009664:Norway / Q000453:epidemiology; D015203:Reproducibility of Results; D012307:Risk Factors; D012680:Sensitivity and Specificity; D014463:Ultrasonography
keywords: Knee; anatomy; congenital; dysplasias; pediatrics; ultrasound