title: Dynamic measurement of patello-femoral joint alignment using weight-bearing magnetic resonance imaging (WB-MRI).
abstract: OBJECTIVE
  Aim of our work was to compare standard and weight-bearing WB-MRI to define their contribution in unmasking patello-femoral (PF) maltracking and to define what measurement of patellar alignment is the most reliable.
  
  
  METHODS
  We prospectively collected 95 non consecutive patients, clinically divided into 2 groups: group A (the control group), including 20 patients (negative for patellar maltracking), and group B including 75 patients (positive for patellar maltracking). The patients underwent a dedicated 0.25 T MRI, in supine and WB position, with knee flexion of 12-15°. The following measurements were performed: Insall-Salvati index (IS), lateral patellar displacement (LPD), lateral patello-femoral angle (LPA) and lateral patellar tilt (LPT). Quantitative and qualitative statistical analyses were performed to compare the results obtained before and after WB-MRI. Measurements were subsequently performed on both groups.
  
  
  RESULTS
  Group A patients showed no statistically significant variations at all measurements both on standard and WB-MRI. On the basis of measurements made on standard MRI, group B patients were divided into group B1 (23 patients) (negative or positive at 1 measurement) and group B2 (52 patients) (positive at 2 or more measurements). After WB-MRI, group B1 patients were divided into group B1a (6 patients), in case they remained positive at 0/1 measurement, and group B1b (17 patients), in case they became positive at 2 or more measurements. All group B2 patients confirmed to be positive at 2 or more measurements at WB-MRI. Quantitative statistical analysis showed that LPT and LPA were the most reproducible and clinically useful measurements. Qualitative statistical analysis performed on standard and WB-MRI demonstrated that LPT was the best predictive measurement.
  
  
  CONCLUSIONS
  This study demonstrates both the high diagnostic value of WB-MRI in unmasking PF-maltracking and the best predictive value of LPT measurement.
authors.affiliation: University of L'Aquila, Department of Biotechnological and Applied Clinical Sciences, S. Salvatore Hospital, L'Aquila, Coppito, Italy. Electronic address: mari.silvia@hotmail.it.
authors.forename: Silvia
authors.initials: S
authors.lastname: Mariani
authors.affiliation: University of L'Aquila, Department of Biotechnological and Applied Clinical Sciences, S. Salvatore Hospital, L'Aquila, Coppito, Italy. Electronic address: alicelm@hotmail.it.
authors.forename: Alice
authors.initials: A
authors.lastname: La Marra
authors.affiliation: University of L'Aquila, Department of Biotechnological and Applied Clinical Sciences, S. Salvatore Hospital, L'Aquila, Coppito, Italy. Electronic address: arrigoni.francesco@gmail.com.
authors.forename: Francesco
authors.initials: F
authors.lastname: Arrigoni
authors.affiliation: University of L'Aquila, Department of Life, Health & Environmental Sciences, L'Aquila, Italy. Electronic address: stefano.necozione@cc.univaq.it.
authors.forename: Stefano
authors.initials: S
authors.lastname: Necozione
authors.affiliation: University of L'Aquila, Department of Biotechnological and Applied Clinical Sciences, S. Salvatore Hospital, L'Aquila, Coppito, Italy. Electronic address: alessandra.splendiani@cc.univaq.it.
authors.forename: Alessandra
authors.initials: A
authors.lastname: Splendiani
authors.affiliation: University of L'Aquila, Department of Biotechnological and Applied Clinical Sciences, S. Salvatore Hospital, L'Aquila, Coppito, Italy. Electronic address: ernesto.dicesare@cc.univaq.it.
authors.forename: Ernesto
authors.initials: E
authors.lastname: Di Cesare
authors.affiliation: University of L'Aquila, Department of Biotechnological and Applied Clinical Sciences, S. Salvatore Hospital, L'Aquila, Coppito, Italy. Electronic address: antonio.barile@cc.univaq.it.
authors.forename: Antonio
authors.initials: A
authors.lastname: Barile
authors.affiliation: University of L'Aquila, Department of Biotechnological and Applied Clinical Sciences, S. Salvatore Hospital, L'Aquila, Coppito, Italy. Electronic address: carlo.masciocchi@cc.univaq.it.
authors.forename: Carlo
authors.initials: C
authors.lastname: Masciocchi
mesh_terms: D000293:Adolescent; D000328:Adult; D005260:Female; D006801:Humans; D007592:Joint Diseases / Q000473:pathology*; D008279:Magnetic Resonance Imaging; D008297:Male; D057071:Patellofemoral Joint / Q000473:pathology*; D011446:Prospective Studies; D015203:Reproducibility of Results; D016474:Weight-Bearing; D055815:Young Adult
keywords: Anterior knee pain; Knee; Patello-femoral joint maltracking; Patello-femoral syndrome; Weight-bearing-MRI