title: Comparison of cartilage thickness with radiologic grade of knee osteoarthritis.
abstract: OBJECTIVE
  To compare joint space width (JSW) measurements obtained from magnetic resonance imaging (MRI) with a semi-automated computer algorithm to the Kellgren and Lawrence grading of osteoarthritis (OA).
  
  
  METHODS
  Three hundred and six patients (234 female, 72 male) with a mean age of 56.7 years (range 31-81 years) underwent MRI of their knees with a fast oblique spiral spoiled gradient (SPGR) sequence. A board-certified musculoskeletal radiologist graded the OA of all the patients in accordance with the Kellgren and Lawrence OA scale. A previously validated computer algorithm was used to determine the minimum JSW for both the tibiofemoral joint and the patellofemoral joint. An analysis of variance (ANOVA) with the Student-Newman-Kuels post-hoc test was used to determine if there were differences in JSW as a function of OA grade.
  
  
  RESULTS
  The radiologic grade of OA was inversely associated with the JSW. In the medial compartment the JSW did not change significantly between grade 1 and grade 2, but there was a significant decrease in JSW between grade 0 (normal) and grade 1 and for each OA grade above grade 2. In the lateral compartment no statistical differences were found till grade 2, while grade 3 was found to be statistically different from the previous one. The number of patients with a grade 4 patellofemoral OA was too low for the statistical significance to be assessed. In the patellofemoral joint the JSW did not change significantly until grade 2, while a statistically significant reduction was found for both grade 3 and grade 4.
  
  
  CONCLUSIONS
  This study showed that an inverse non-linear relationship exists between radiologic grade and JSW. The relationship differs for the tibiofemoral and the patellofemoral joint.
authors.affiliation: Motion Analysis Laboratory, Division of Orthopedic Research, Mayo Clinic, Rochester, MN 55905, USA.
authors.forename: Filippo
authors.initials: F
authors.lastname: Agnesi
authors.forename: Kimberly K
authors.initials: KK
authors.lastname: Amrami
authors.forename: Carlo A
authors.initials: CA
authors.lastname: Frigo
authors.forename: Kenton R
authors.initials: KR
authors.lastname: Kaufman
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D002358:Cartilage, Articular / Q000473:pathology*; D005260:Female; D006801:Humans; D008279:Magnetic Resonance Imaging / Q000379:methods*; D008297:Male; D008875:Middle Aged; D020370:Osteoarthritis, Knee / Q000175:diagnosis*; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D013223:Statistics as Topic