title: The value of computed tomography for the diagnosis of recurrent patellar subluxation in adolescents.
abstract: OBJECTIVE
  To determine if computed tomography of the patellofemoral joint has any advantage over standard radiologic techniques in the evaluation of recurrent patellar subluxation.
  
  
  METHODS
  A case series.
  
  
  METHODS
  A tertiary children's hospital out-patient clinic.
  
  
  METHODS
  Forty consecutive adolescents with a clinical diagnosis of recurrent patellar subluxation (study group) and 14 volunteers with normal knees (control group).
  
  
  METHODS
  A standardized radiologic protocol, including axial views of the patella at 30 degrees of knee flexion, with and without external torsion of the tibia, and computed tomography (CT) of the patella at 15 degrees of knee flexion.
  
  
  METHODS
  The lateral patellofemoral angle on the axial views and on the CT scan and patellar centralization on the CT scan.
  
  
  RESULTS
  In the control group, no radiologic evidence of recurrent patellar subluxation was found. In the study group, an abnormal lateral patellofemoral angle was found in 25% of axial views; this rate increased to 42% with external rotation and 86% on the CT scan. Patellar centralization was abnormal in 79% of cases.
  
  
  CONCLUSIONS
  CT of the patellofemoral joint is more sensitive than standard radiographs for the diagnosis of recurrent patellar subluxation. The use of CT is recommended when standard radiographs appear normal.
authors.affiliation: Orthopedic Service, Sainte-Justine Hospital, Montreal, Que.
authors.forename: C
authors.initials: C
authors.lastname: Stanciu
authors.forename: H B
authors.initials: HB
authors.lastname: Labelle
authors.forename: B
authors.initials: B
authors.lastname: Morin
authors.forename: F
authors.initials: F
authors.lastname: Fassier
authors.forename: D
authors.initials: D
authors.lastname: Marton
mesh_terms: D000293:Adolescent; D006801:Humans; D004204:Joint Dislocations / Q000000981:diagnostic imaging*; D007719:Knee Joint / Q000000981:diagnostic imaging; D010329:Patella / Q000000981:diagnostic imaging*; D012008:Recurrence; D014057:Tomography, X-Ray Computed