Fixed-flexion radiography of the knee provides reproducible joint space width measurements in osteoarthritis
- 597 Downloads
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° 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.
KeywordsKnee Osteoarthritis Radiography Joint space width
This image acquisition for this study was funded by Hoffman-La Roche. Authors thank Melissa M. Ta from Synarc for providing the drawings.
- 3.Lequesne M, Brandt K, Bellamy N et al (1995) Guidelines for testing slow acting drugs in arthritis—addendum. J Rheumatol 22:1442Google Scholar
- 6.Brandt KD, Fife RS, Braunstein EM, Katz B (1991) Radiographic grading of the severity of knee osteoarthritis: relation of the Kellgren and Lawrence grade to a grade based on joint space narrowing, and correlation with arthroscopic evidence of articular cartilage degeneration. Arthritis Rheum 34:1381–1386PubMedGoogle Scholar
- 25.Altman DG (1991) Practical statistics for medical research. Chapman & Hall, LondonGoogle Scholar
- 26.Mazzuca SA, Brandt KD, Buckwalter KA, Lane KA, Katz BP (2002) Field test of the reproducibility of the semiflexed metatarsophalangeal view in repeated radiographic examinations of subjects with osteoarthritis of the knee. Arthritis Rheum 46:109–113Google Scholar