title: Are the osseous and tendinous-cartilaginous tibial tuberosity-trochlear groove distances the same on CT and MRI?
abstract: OBJECTIVE
  To verify whether the tibial tuberosity-trochlear groove distance (TT-TG) and the tendinous-cartilaginous TT-TG (the distance between the patellar tendon and trochlear groove: PT-TG) are identical using computed tomography (CT) and magnetic resonance imaging (MRI) techniques.
  
  
  METHODS
  The TT-TG and PT-TG distances were measured on the same knee samples by three observers (two measurements per observer) using CT and MRI scans collected retrospectively. The reproducibility of the measurements was assessed using the interclass correlation coefficient (ICC). The means and standard deviations of four measurements were calculated for each patient. A paired t-test was used to assess differences between measurements.
  
  
  RESULTS
  Fifty knee samples (32 with patellar instability and 18 with other conditions) were evaluated. The inter- and intraobserver reliability was excellent for all four measurements (>0.8). On average, the TT-TG distance on MRI was 3.1-3.6 mm smaller than that on CT, and the PT-TG distance on MRI was 1.0-3.4 mm larger than the TT-TG distance on MRI.
  
  
  CONCLUSIONS
  The osseous TT-TG and tendinous-cartilaginous PT-TG distances determined by CT and MRI were not identical.
authors.affiliation: Department of Orthopaedics, Institute of Orthopaedics and Traumatology of the Clinical Hospital of the Medical School of the University of São Paulo, São Paulo, Brazil, betinahinckel@gmail.com.
authors.forename: Betina Bremer
authors.initials: BB
authors.lastname: Hinckel
authors.forename: Riccardo Gomes
authors.initials: RG
authors.lastname: Gobbi
authors.forename: Eduardo Noda Kihara
authors.initials: EN
authors.lastname: Filho
authors.forename: José Ricardo
authors.initials: JR
authors.lastname: Pécora
authors.forename: Gilberto Luis
authors.initials: GL
authors.lastname: Camanho
authors.forename: Marcelo Bordalo
authors.initials: MB
authors.lastname: Rodrigues
authors.forename: Marco Kawamura
authors.initials: MK
authors.lastname: Demange
mesh_terms: D000293:Adolescent; D000328:Adult; D002356:Cartilage / Q000033:anatomy & histology* / Q000000981:diagnostic imaging; D005260:Female; D006801:Humans; D008279:Magnetic Resonance Imaging / Q000379:methods*; D008297:Male; D008875:Middle Aged; D008953:Models, Anatomic; D015588:Observer Variation; D057071:Patellofemoral Joint / Q000033:anatomy & histology* / Q000000981:diagnostic imaging; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D013710:Tendons / Q000033:anatomy & histology* / Q000000981:diagnostic imaging; D013977:Tibia / Q000033:anatomy & histology* / Q000000981:diagnostic imaging; D014057:Tomography, X-Ray Computed / Q000379:methods*; D055815:Young Adult