Curtis Hayes MD, PRESENTER: Nothing to Disclose

Abstract: HTML Purpose: Two accepted endpoints in the evaluation of knee osteoarthritis (OAK) progression are: 1) joint space narrowing (JSN), and 2) osteophyte growth. Quantitative methods of assessing JSN have been validated. However, methods of assessing short-interval osteophyte growth have not been validated. The purpose of this study was to test the intra-observer variability of a semi-quantitative method of assessing tibial osteophyte growth in OAK using highly standardized radiographs. Methods and Materials: From a cohort of 1200 subjects involved in a multicenter OAK trial, 50 sets of serial knee radiographs were randomly selected. All subjects had radiographic OAK based on JSN and at least one osteophyte. Radiographs were obtained using the fluoroscopically positioned semi-flexed AP technique (Buckland-Wright), under rigorous quality control. Each subject had baseline, 12-month, and 24-month radiographs of the signal knee. Radiographs were presented as blinded triplets (A, B, C) to a musculoskeletal radiologist, who compared A:B, B:C, and C:A for apparent change in osteophyte size. A 4-grade semiquantitative system was used, which included a method of assessing for confounding effects of knee rotation. The blinded comparison was repeated 2 weeks later, in re-randomized order. Results were analyzed for intra-observer variability, and for outcome based on the unblinded temporal sequence. (IRB approval was obtained for this study.) Results: The weighted agreement rate was 407 matches out of 450 events (90%) between the two sessions. The kappa score was 0.87. At 12 months, osteophyte growth was detected at the lateral tibia, medial tibia, and tibial spines in 12%, 20-24%, and 8-10% of knees, respectively. At 24 months growth was detected in 12-14%, 30-40%, and 10-12%, respectively. Paradoxical apparent decrease in osteophyte size was found at 12 months in 0% (lateral), 2-6% (medial), and 0% (tibial spine), and at 24 months in 0% (lateral), 0% (medial), and 0-2% (tibial spine). Conclusion: Using fluoroscopically positioned semi-flexed knee radiographs, and a semi-quantitative system, reproducible assessment of osteophyte growth was possible with a single expert reader at 12- and 24-months, in this population. Variation in knee rotation is likely responsible for paradoxical apparent decrease in osteophyte size in a small number of cases. Therefore, when obtaining standardized knee radiographs for the purpose of assessing OAK, attention should be paid to the degree of rotation as well as the reproducibility of knee flexion. (C.W.H. is a consultant to and received financial support for this study from Proctor & Gamble Pharmaceuticals, Inc.) Questions about this event email: cwhayes@vcu.edu

Hayes MD, C, Standardized Assessment of Tibial Osteophyte Growth in Knee Osteoarthritis.  Radiological Society of North America 2003 Scientific Assembly and Annual Meeting, November 30 - December 5, 2003 ,Chicago IL. http://archive.rsna.org/2003/3102504.html