title: Joint-space width in the axial view of the patello-femoral joint. Definitions and comparison with MR imaging.
abstract: OBJECTIVE
  To validate a bony landmark on the dorsal aspect of the patella for measurement of the interbone distance in the axial radiogram of the patello-femoral joint (PFJ); to assess the reproducibility of this radiogram and the minimal joint-space (MJS) width measurements in the medial and lateral compartments of the PFJ in this view; and to relate the MJS of the PFJ to MR-detected cartilage defects in the same joint.
  
  
  METHODS
  Fifty-seven individuals with chronic knee pain (aged 41-58 years, mean 50 years) were examined with an axial view of the PFJ in the standing position. The MJS was measured with a mm-graded ruler. On the same day, an MR examination was performed with proton density- and T2-weighted turbo spin-echo sequences on a 1.0 T imager. We noted the cartilage defects in the PFJ in axial and sagittal MR images, and the shape of the subchondral cortex of the medial and lateral articular surfaces of the patella in sagittal MR images.
  
  
  CONCLUSIONS
  The bony landmark was found on all articular surfaces. The axial view of the PFJ and the MJS measurements were reproducible. An MJS of <5 mm showed high specificity for MR-detected cartilage defects. Thus an MJS of 5 mm proved to be a limit in the diagnosis of joint-space narrowing in the PFJ in middle-aged individuals with chronic knee pain.
authors.affiliation: Department of Diagnostic Radiology, County Hospital, Helsingborg, Sweden.
authors.forename: T
authors.initials: T
authors.lastname: Boegård
authors.forename: O
authors.initials: O
authors.lastname: Rudling
authors.forename: I F
authors.initials: IF
authors.lastname: Petersson
authors.forename: J
authors.initials: J
authors.lastname: Sanfridsson
authors.forename: T
authors.initials: T
authors.lastname: Saxne
authors.forename: B
authors.initials: B
authors.lastname: Svensson
authors.forename: K
authors.initials: K
authors.lastname: Jonsson
mesh_terms: D000328:Adult; D018771:Arthralgia / Q000175:diagnosis* / Q000453:epidemiology / Q000209:etiology; D002358:Cartilage, Articular / Q000000981:diagnostic imaging / Q000473:pathology; D002908:Chronic Disease; D005260:Female; D005269:Femur / Q000000981:diagnostic imaging / Q000473:pathology; D005500:Follow-Up Studies; D006801:Humans; D007719:Knee Joint / Q000473:pathology; D008279:Magnetic Resonance Imaging; D008297:Male; D008875:Middle Aged; D015588:Observer Variation; D010329:Patella / Q000000981:diagnostic imaging / Q000473:pathology; D011446:Prospective Studies; D011859:Radiography; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D011795:Surveys and Questionnaires; D013548:Sweden / Q000453:epidemiology