Validity of histopathological grading of articular cartilage from osteoarthritic knee joints

Objectives-To determine the validity of the histological-histochemical grad ing system (HHGS) for osteoarthritic (OA) articular cartilage. Methods-Human articular cartilage was obtained from macroscopically normal (n 13) and OA (n = 21) knee joints. Sections of central and peripheral regi ons of normal samples were produced. Sections of regions containing severe, moderate, and mild OA changes were produced from each OA sample. A total o f 89 sections were graded by means of the HHGS (0-14) twice by three observ ers. Results-Average scores for regions designated severe (8.64) and moderate (5 .83) OA were less than the expected (10-14 and 6-9, respectively) according to the HHGS, whereas average scores for the region designated mild (5.29) OA and central and peripheral regions (2.19) of normal cartilage were highe r than expected (2-5 and 0-1, respectively). The HHGS was capable of differ entiating between articular cartilage from macroscopically normal and OA jo ints and between the region designated severe OA and other regions. However , the HHGS did not adequately differentiate between regions designated mild and moderate OA. Values for sensitivity, specificity, and efficiency for a ll regions varied considerably. Conclusion-The HHGS is valid for normal and severe OA cartilage, but does n ot permit distinction between mild and moderate OA changes in articular car tilage.