The OARSI cartilage OA histopathology grading system appears consistent and simple to apply. Further studies are required to confirm the system's utility.

YKL-40 in SF is derived from cells in the inflamed synovium, chondrocytes and SF neutrophils. Joint derived YKL-40 influences serum YKL-40. YKL-40 may be involved in the pathophysiology of the arthritic processes and reflect local disease activity.

Men and women demonstrate impressive levels of muscular strength in the flexors and extensors of the cervical spine and can maintain these values until the seventh decade of life. Successful rehabilitation of the cervical musculature will require considerable resistance for sufficient stimulation of the cervical musculature.

Objectives-To determine the validity of the histological-histochemical grading 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 regions of normal samples were produced. Sections of regions containing severe, moderate, and mild OA changes were produced from each OA sample. A total of 89 sections were graded by means of the HHGS (0-14) twice by three observers. 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 higher than expected (2-5 and 0-1, respectively). The HHGS was capable of diVerentiating between articular cartilage from macroscopically normal and OA joints and between the region designated severe OA and other regions. However, the HHGS did not adequately diVerentiate between regions designated mild and moderate OA. Values for sensitivity, specificity, and eYciency for all regions varied considerably. Conclusion-The HHGS is valid for normal and severe OA cartilage, but does not permit distinction between mild and moderate OA changes in articular cartilage. (Ann Rheum Dis 1999;58:208-213) The histopathology of osteoarthritis (OA) is generally graded using the histologicalhistochemical grading system (HHGS) proposed by Mankin et al 1 or a number of histopathological grading systems that are modifications of the original system. 2-7 The HHGS was initially developed for the grading of OA in human articular cartilage 1 and has been used extensively in human studies. More recently, the HHGS and modifications thereof have also become extensively used for the grading of articular cartilage from animal models of OA. We have previously investigated the intraobserver and interobserver reproducibilities of the HHGS based on human articular cartilage 30 and concluded that they were inadequate. Similar values regarding the intraobserver and interobserver reproducibilities of the HHGS have been reported in a study on materials from an experimental animal model of OA. 31 The results of our previous study also indicated that the validity of the HHGS was questionable. It is of paramount importance to determine if the HHGS is valid. A valid grading system with inadequate intraobserver and interobserver reproducibilities could and should be improved upon. However, a grading system that is not valid should be disregarded altogether and replaced by a completely new grading system.To evaluate the validity of a histopathological grading system the results obtained when using the system should be compared with the results of a system already known to be valid. Unfortunately, a valid grading system capable of serving as "the gold standard" does not exist for OA articular cartilage at the histological level.Therefore, the pur...

Objective-The objective of this study was to detail the topographical and zonal distribution of and subunits of the integrin superfamily in normal and osteoarthritic cartilage. Methods-Immunohistochemistry utilising antibodies towardsand subunits was performed on cryostat sections of human articular cartilage from macroscopically normal (n = 6) and osteoarthritic (n = 6) femoral heads. Samples of articular cartilage were obtained from 12 topographically distinct sites from each femoral head. Each section was divided into zones (superficial, middle, deep) and staining scores were recorded. Results-Normal cartilage stained for integrin subunits 1, 5, V, 1, 4, and 5, but not for 2, 3, 4, 6, 2, 3, and 6. Intact and non-intact residual cartilage from osteoarthritic femoral heads stained for 1, 2, 5, V, 1, 4, and 5. Staining was occasionally seen for 4 and 2, but not for 3, 6, 3, and 6. There was no topographical variation in the staining for any of the subunits in either normal or osteoarthritic cartilage. The only subunit that displayed a zonal variation was V; staining for this subunit was most pronounced in the superficial zone compared with the middle and deep zones. Conclusion-Chondrocytes in normal and osteoarthritic cartilage express the integrin subunits 1, 5, V, 1, 4, and 5. Chondrocytes in osteoarthritic cartilage, in addition, express the 2, 4, and 2 subunits. The v subunit is expressed by more chondrocytes in the superficial zone in comparison with cells in the deeper zones. None of the subunits display topographical variation in expression.