title: Fixed-flexion radiography of the knee provides reproducible joint space width measurements in osteoarthritis.
abstract: The validity of a non-fluoroscopic fixed-flexion radiographic acquisition and analysis protocol for measurement of joint space width (JSW) in knee osteoarthritis is determined. A cross-sectional study of 165 patients with documented knee osteoarthritis participating in a multicenter, prospective study of chondroprotective agents was performed. All patients had posteroanterior, weight-bearing, fixed-flexion radiography with 10 degrees caudal beam angulation. A specially designed frame (SynaFlexer) was used to standardize the positioning. Minimum medial and lateral JSW were measured manually and twice by an automated analysis system to determine inter-technique and intra-reader concordance and reliability. A random subsample of 30 patients had repeat knee radiographs 2 weeks apart to estimate short-term reproducibility using automated analysis. Concordance between manual and automated medial JSW measurements was high (ICC=0.90); lateral compartment measurements showed somewhat less concordance (ICC=0.72). There was excellent concordance between repeated automated JSW measurements performed 6 months apart for the medial (ICC=0.94) and lateral (ICC=0.86) compartments. Short-term reproducibility for the subsample of 30 cases with repeat acquisitions demonstrated an average SD of 0.14 mm for medial JSW (CV=4.3%) and 0.23 mm for lateral JSW (CV=4.0%). Fixed-flexion radiography of the knee using a positioning device provides consistent, reliable and reproducible measurement of minimum JSW in knee osteoarthritis without the need for concurrent fluoroscopic guidance.
authors.affiliation: Department of Scientific Client Services, Synarc, Inc., 575 Market Street, 17th Floor, San Francisco, CA 94105, USA.
authors.forename: Manish
authors.initials: M
authors.lastname: Kothari
authors.forename: Ali
authors.initials: A
authors.lastname: Guermazi
authors.forename: Gabriele
authors.initials: G
authors.lastname: von Ingersleben
authors.forename: Yves
authors.initials: Y
authors.lastname: Miaux
authors.forename: Martine
authors.initials: M
authors.lastname: Sieffert
authors.forename: Jon E
authors.initials: JE
authors.lastname: Block
authors.forename: Randall
authors.initials: R
authors.lastname: Stevens
authors.forename: Charles G
authors.initials: CG
authors.lastname: Peterfy
mesh_terms: D000368:Aged; D001175:Arthrography / Q000592:standards*; D002138:Calibration; D005260:Female; D006801:Humans; D007091:Image Processing, Computer-Assisted / Q000592:standards*; D007719:Knee Joint / Q000000981:diagnostic imaging* / Q000187:drug effects; D008297:Male; D008875:Middle Aged; D020370:Osteoarthritis, Knee / Q000000981:diagnostic imaging*; D019047:Phantoms, Imaging; D011446:Prospective Studies; D016059:Range of Motion, Articular / Q000187:drug effects / Q000502:physiology*; D012016:Reference Values; D015203:Reproducibility of Results; D016474:Weight-Bearing / Q000502:physiology*