title: Comparison of MRI-based assessment systems for osteoarthritic knees: the irregularity index system and WORMS.
abstract: OBJECTIVE
  Several MRI-based evaluation systems for osteoarthritis (OA) of the knee have been developed. Among them the whole-organ magnetic resonance imaging score (WORMS), which evaluates the status of the entire knee joint, appears to be representative. We developed an irregularity index system to measure irregularities of the contours of the femoral condyle on MRI. Only the contour of the condyle was assessed by the irregularity index, whereas several items comprising the knee joint were taken into account by WORMS. This study compared the irregularity index and WORMS in terms of their correlations with clinical scores.
  
  
  METHODS
  Thirty-one medial-type OA knees were studied. Kellgren-Lawrence grading was used for X-ray grading: 8 were grade II, 11 were grade III, and 12 were grade IV. Japanese Orthopaedic Association scores and Japanese knee osteoarthritis measure scores were used for clinical assessments. We determined the correlations between MRI-based assessment scores and clinical scores.
  
  
  RESULTS
  Both the irregularity index and WORMS exhibited positive correlations with these clinical scores. The irregularity index was associated with bone cysts of the medial compartment and menisci in the articular features of WORMS.
  
  
  CONCLUSIONS
  These MRI-based methods are useful for evaluating OA severity. However, the irregularity index may have advantages over WORMS because of its semi-automatic features.
authors.affiliation: Department of Orthopaedic Surgery, Graduate School of Medicine, Chiba University, 1-8-1 Inohana, Chuo-ku, Chiba, 260-8670, Japan.
authors.forename: Kei O
authors.initials: KO
authors.lastname: Matsuki
authors.forename: Takahisa
authors.initials: T
authors.lastname: Sasho
authors.forename: Koichi
authors.initials: K
authors.lastname: Nakagawa
authors.forename: Nobuyasu
authors.initials: N
authors.lastname: Ochiai
authors.forename: Satoshi
authors.initials: S
authors.lastname: Yamaguchi
authors.forename: Masahiko
authors.initials: M
authors.lastname: Saito
authors.forename: Naoshi
authors.initials: N
authors.lastname: Ikegawa
authors.forename: Ryuichiro
authors.initials: R
authors.lastname: Akagi
authors.forename: Atsuya
authors.initials: A
authors.lastname: Watanabe
authors.forename: Yuichi
authors.initials: Y
authors.lastname: Wada
authors.forename: Keisuke
authors.initials: K
authors.lastname: Matsuki
authors.forename: Kazuhisa
authors.initials: K
authors.lastname: Takahashi
mesh_terms: D000368:Aged; D005260:Female; D006801:Humans; D008279:Magnetic Resonance Imaging / Q000379:methods*; D008297:Male; D020370:Osteoarthritis, Knee / Q000175:diagnosis*