Cross-sectional comparison of extended anteroposterior and posteroanterior fixed flexion positioning to assess radiographic osteoarthritis at the knee: The Johnston County Osteoarthritis Project
Article first published online: 2 SEP 2010
Copyright © 2010 by the American College of Rheumatology
Arthritis Care & Research
Volume 62, Issue 9, pages 1342–1345, September 2010
How to Cite
Nelson, A. E., Renner, J. B., Shi, X. A., Shreffler, J. H., Schwartz, T. A. and Jordan, J. M. (2010), Cross-sectional comparison of extended anteroposterior and posteroanterior fixed flexion positioning to assess radiographic osteoarthritis at the knee: The Johnston County Osteoarthritis Project. Arthritis Care Res, 62: 1342–1345. doi: 10.1002/acr.20210
- Issue published online: 2 SEP 2010
- Article first published online: 2 SEP 2010
- Accepted manuscript online: 9 APR 2010 12:00AM EST
- Manuscript Accepted: 2 APR 2010
- Manuscript Received: 13 JAN 2010
- American College of Rheumatology Research and Education Foundation Clinical Investigator Fellowship award
- NIH loan repayment. Grant Number: 1-L30-AR056604
- CDC/Association of Schools of Public Health. Grant Numbers: S043, S3486
- NIH/National Institute of Arthritis and Musculoskeletal and Skin Diseases Multipurpose Arthritis and Musculoskeletal Diseases Center. Grant Number: 5-P60-AR49465
- NIH/National Institute of Arthritis and Musculoskeletal and Skin Diseases. Grant Number: 5-R01-AR053989
To compare values for Kellgren/Lawrence (K/L) scale grade, joint space narrowing (JSN), and osteophytes in anteroposterior (AP) extended and fixed flexion posteroanterior (PA) radiographs obtained during a single clinic visit (the first followup of the Johnston County Osteoarthritis Project).
All films (n = 1,664 bilateral knees) were read by an experienced musculoskeletal radiologist. For each subject, AP and PA fixed flexion films were read in one sitting. K/L scale grades (range 0–4) and JSN and osteophytes (ranges 0–3) were assessed using standard atlases. Descriptive statistics were calculated for demographic and clinical variables. AP and PA fixed flexion results were compared by contingency table methods to obtain frequencies for K/L scale, JSN, and osteophyte grades using percent agreement and kappa coefficients. Results from the right and left knees were similar; data for the right knee are presented.
There was substantial agreement between AP and PA fixed flexion reads for radiographic osteoarthritis, defined as a K/L scale grade ≥2 (89% agreement; κ = 0.73, 95% confidence interval 0.69–0.76). Substantial agreement was also seen for tibial osteophytes and medial JSN; slightly lower kappa values were observed for femoral osteophytes and lateral JSN.
The requirements of large observational cohort studies are different than those of clinical trials, and sensitivity is less of an issue because of longer followup times. In cohort studies such as the Johnston County Osteoarthritis Project, there is substantial agreement by K/L scale grade for AP and PA fixed flexion radiographs, allowing incorporation of older films in longitudinal analyses.