Histologic/histochemical grading system for osteoarthritic articular cartilage. Reproducibility and validity

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Abstract
Objective. To evaluate the reproducibility and validity of the histologic/histochemical grading system (HHGS) for osteoarthritis (OA) developed by Mankin and coworkers. Methods. Sections of human articular cartilage from macroscopically normal and osteoarthritic femoral heads were graded by the HHGS (0-14 scale) twice by 3 observers, and intra- and interobserver reproducibility was determined. Results. The exact intra- and interobserver reproducibilities ranged from 22% to 33% and from 13% to 25%, respectively. Intra- and interobserver variation ranged from −7 to 5. Although scores were generally higher in cartilage from osteoarthritic joints as compared with cartilage from normal joints, the difference reached statistical significance for only 2 observers. Additionally, the average scores from all observers were within the definitive range for OA (>5) in 30% of sections from normal joints, and in only 47% of sections from OA joints. Conclusion. The results indicate that the reproducibility and the validity of the HHGS are inadequate, and an improved histopathologic grading system for OA is needed.