title: MRI after unicondylar knee arthroplasty: the preserved compartments.
abstract: OBJECTIVE
  The aim of this study was to assess the reproducibility of using magnetic resonance imaging (MRI) to analyze the preserved anatomic knee compartments following unicondylar knee arthroplasty (UKA) with zirconium femoral components. It was hypothesized that evaluation of the cartilage, ligaments, meniscus, and tendons would result in a high rate of inter-observer reliability.
  
  
  METHODS
  Ten patients underwent MRI of the knee tailored to reduce metallic artifact following medial UKA with zirconium femoral implants. Cartilage, external meniscus, collateral and cruciate ligaments, the quadriceps and patellar tendons, and the presence of joint effusion were evaluated by two independent investigators. The reviewers provided degrees of confidence with their evaluation of each parameter through the use of a five-point scale. Inter-observer agreement was calculated and inter-observer reliability was determined by use of Cohen's Kappa. Artifacts originating from the implants were rarely observed. There was excellent inter-observer reliability (i.e., high Cohen's Kappa) for all assessed structures, and a high level of observer confidence for the evaluation of the cartilage, meniscus, tendons, ligaments, and joint effusion.
  
  
  CONCLUSIONS
  In this study tailored MRI allows for reproducible analysis of the preserved knee joint compartment after UKA for zirconium implants. This technique might prove helpful in the assessment of painful knee joints after UKA with other metallic materials as new MRI software programs, which suppress metal artifacts, are developed.
authors.affiliation: Department of Orthopedics and Rheumatology, University Hospital Marburg, Germany. heyse@med.uni-marburg.de
authors.forename: Thomas J
authors.initials: TJ
authors.lastname: Heyse
authors.forename: Jens
authors.initials: J
authors.lastname: Figiel
authors.forename: Ulrike
authors.initials: U
authors.lastname: Hähnlein
authors.forename: Nina
authors.initials: N
authors.lastname: Timmesfeld
authors.forename: Jan
authors.initials: J
authors.lastname: Schmitt
authors.forename: Markus D
authors.initials: MD
authors.lastname: Schofer
authors.forename: Susanne
authors.initials: S
authors.lastname: Fuchs-Winkelmann
authors.forename: Turgay
authors.initials: T
authors.lastname: Efe
mesh_terms: D000368:Aged; D019645:Arthroplasty, Replacement, Knee; D002358:Cartilage, Articular / Q000473:pathology*; D015331:Cohort Studies; D005260:Female; D006801:Humans; D007720:Knee Prosthesis; D008023:Ligaments, Articular / Q000473:pathology*; D008279:Magnetic Resonance Imaging; D008297:Male; D008592:Menisci, Tibial / Q000473:pathology*; D008875:Middle Aged; D011474:Prosthesis Design; D015203:Reproducibility of Results; D016896:Treatment Outcome; D015040:Zirconium
chemical_list: D015040:Zirconium