title: How reliable is MRI in diagnosing cartilaginous lesions in patients with first and recurrent lateral patellar dislocations?
abstract: BACKGROUND
  Lateral dislocation of the patella (LPD) leads to cartilaginous injuries, which have been reported to be associated with retropatellar complaints and the development of patellofemoral osteoarthritis. Therefore, the purpose of this study was to determine the reliability of MRI for cartilage diagnostics after a first and recurrent LPD.
  
  
  METHODS
  After an average of 4.7 days following an acute LPD, 40 patients (21 with first LPDs and 19 with recurrent LPDs) underwent standardized 1.5 Tesla MRI (sagittal T1-TSE, coronal STIR-TSE, transversal fat-suppressed PD-TSE, sagittal fat-suppressed PD-TSE). MRI grading was compared to arthroscopic assessment of the cartilage.
  
  
  RESULTS
  Sensitivities and positive predictive values for grade 3 and 4 lesions were markedly higher in the patient group with first LPDs compared to the group with recurrent LPDs. Similarly, intra- and inter-observer agreement yielded higher kappa values in patients with first LPDs compared to those with recurrent LPDs. All grade 4 lesions affecting the subchondral bone (osteochondral defects), such as a fissuring or erosion, were correctly assessed on MRI.
  
  
  CONCLUSIONS
  This study demonstrated a comparatively good diagnostic performance for MRI in the evaluation of first and recurrent LPDs, and we therefore recommend MRI for the cartilage assessment after a LPD.
authors.affiliation: Department of Trauma and Orthopedic Surgery, HELIOS-Klinikum Wuppertal, Heusnerstr, 40, 42283 Wuppertal, University of Witten/Herdecke, Germany. larsvictor@gmx.de
authors.forename: Lars V
authors.initials: LV
authors.lastname: von Engelhardt
authors.forename: Marthina
authors.initials: M
authors.lastname: Raddatz
authors.forename: Bertil
authors.initials: B
authors.lastname: Bouillon
authors.forename: Gunter
authors.initials: G
authors.lastname: Spahn
authors.forename: Andreas
authors.initials: A
authors.lastname: Dàvid
authors.forename: Patrick
authors.initials: P
authors.lastname: Haage
authors.forename: Thomas K
authors.initials: TK
authors.lastname: Lichtinger
mesh_terms: D000293:Adolescent; D000328:Adult; D001182:Arthroscopy; D002358:Cartilage, Articular / Q000473:pathology*; D002908:Chronic Disease; D005260:Female; D005269:Femur / Q000473:pathology*; D006801:Humans; D008279:Magnetic Resonance Imaging / Q000379:methods; D008297:Male; D010329:Patella / Q000473:pathology*; D031222:Patellar Dislocation / Q000175:diagnosis* / Q000473:pathology; D011237:Predictive Value of Tests; D012008:Recurrence; D015203:Reproducibility of Results; D055815:Young Adult