Objective-This study tested the reliability of a 5-point ordinal scale used to grade the severity of degenerative changes of zygapophyseal (Z) joints on standard radiographs. CORRESPONDING AUTHOR CONTACT INFORMATION: Gregory D. Cramer, DC, PhD, gcramer@nuhs.edu or gregorycramer@sbcglobal.net, NUHS, 200 E. Roosevelt Rd., Lombard, IL 60148,.
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Author ManuscriptMethods-Modifications were made to Kellgren's grading system to improve agreement for grading the severity of osteoarthritic changes in lumbar Z joints. These included adding 1 grade of no degeneration, multiple radiographic views, and structured examiner training. Thirty packets of radiographic files were obtained, which included representation of all 5 grades including no degeneration (0) and Kellgren's 4-point (1 to 4) joint degeneration classification criteria. Radiographs were digitized to create a radiographic atlas that was given to examiners for individual study and blinded evaluation sessions. Intra-rater and inter-rater agreement was determined by weighted kappa (κ w ) from the examination of 79 Z joints (25 packets).Results-Using the modified scale and following training, examiners demonstrated a moderate to substantial level of inter-rater agreement (κ w = 0.57, 0.60, and 0.68). Intra-rater agreement was moderate (κ w = 0.42 and 0.54).Conclusions-The modified Kellgren 5-point grading system provides acceptable intra-and inter-rater reliability when examiners are adequately trained. This grading system may be a useful method for future investigations assessing radiographic osteoarthritis of the Z joints. v