title: Anatomical factors influencing patellar tracking in the unstable patellofemoral joint.
abstract: OBJECTIVE
  The current study was performed to relate anatomical parameters to in vivo patellar tracking for pediatric patients with recurrent patellar instability.
  
  
  METHODS
  Seven pediatric patients with recurrent patellar instability that failed conservative treatment were evaluated using computational reconstruction of in vivo patellofemoral function. Computational models were created from high-resolution MRI scans of the unloaded knee and lower-resolution scans during isometric knee extension at multiple flexion angles. Shape matching techniques were applied to replace the low-resolution models of the loaded knee with the high-resolution models. Patellar tracking was characterized by the bisect offset index (lateral shift) and lateral tilt. Anatomical parameters were characterized by the inclination of the lateral ridge of the trochlear groove, the tibial tuberosity-trochlear groove distance, the Insall-Salvati index and the Caton-Deschamps index. Stepwise multivariable linear regression analysis was used to relate patellar tracking to the anatomical parameters.
  
  
  RESULTS
  The bisect offset index and lateral tilt were significantly correlated with the lateral trochlear inclination (p≤0.002) and TT-TG distance (p<0.05), but not the Insall-Salvati index or the Caton-Deschamps index. For both the bisect offset index and lateral tilt, the standardized beta coefficient, used to identify the best anatomical predictors of tracking, was larger for the lateral trochlear inclination than the TT-TG distance.
  
  
  CONCLUSIONS
  For this population, the strongest predictor of lateral maltracking that could lead to patellar instability was lateral trochlear inclination.
  
  
  METHODS
  Diagnostic study, Level II.
authors: Department of Orthopedic Surgery, Akron General Medical Center, Akron, OH, USA.
authors: Rahul
authors: R
authors: Biyani
authors: John J
authors: JJ
authors: Elias
authors: Archana
authors: A
authors: Saranathan
authors: Hao
authors: H
authors: Feng
authors: Loredana M
authors: LM
authors: Guseila
authors: Melanie A
authors: MA
authors: Morscher
authors: Kerwyn C
authors: KC
authors: Jones
mesh_terms: D000293:Adolescent; D005260:Female; D006801:Humans; D007091:Image Processing, Computer-Assisted; D007593:Joint Instability / Q000503:physiopathology* / Q000601:surgery; D007719:Knee Joint; D016014:Linear Models; D008279:Magnetic Resonance Imaging; D008297:Male; D008954:Models, Biological; D010329:Patella / Q000503:physiopathology*; D057071:Patellofemoral Joint / Q000503:physiopathology*; D016059:Range of Motion, Articular; D012044:Regression Analysis; D013977:Tibia / Q000601:surgery; D055815:Young Adult