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OBJECTIVE Thrombospondin-1 (TSP-1), a trimeric glycoprotein, is involved in cell-matrix interactions of various tissues, particularly in cartilage. Biochemical analyses show expression of TSP-1 in human cartilage, but its cellular source as well as the presence of its main surface receptors CD36 and CD51 in normal and osteoarthritic cartilage remain unknown. Therefore, to localise TSP-1 and its receptors immunohistochemistry and in situ hybridisation were used. METHODS Radioactive in situ hybridisations with an RNA probe that encodes TSP-1 combined with immunostaining were carried out to investigate the expression patterns of TSP-1, CD36, and CD51 in seven normal and 23 osteoarthritic human cartilage samples. RESULTS In normal cartilage TSP-1 was present mainly in the middle and upper deep zone. RNA expression was predominantly seen over chondrocytes of the middle zone. CD36 was found in chondrocytes of the superficial and upper middle zone. In mild and moderate osteoarthritic cartilage an increased number of TSP-1 expressing chondrocytes were seen and an increased pericellular staining close to the surface. In severe osteoarthritic cartilage a decrease in the number of TSP-1 synthesising chondrocytes and a strong reduction in matrix staining were observed. Most of these severe osteoarthritic samples showed a strongly enhanced number of CD36 positive chondrocytes. CONCLUSION The cellular source of TSP-1 in normal cartilage is mainly mid-zone chondrocytes, which also express CD36. In early osteoarthritic cartilage lesions an increase of TSP-1 was seen, whereas reduced TSP-1 synthesis is paralleled by a strong decrease in TSP-1 protein staining in severe osteoarthritis. Furthermore, in severe osteoarthritic cartilage the number of CD36 immunostained chondrocytes is significantly increased.

The results of cementless tapered designed femoral stem were studied at a minimum 10-year follow-up in a non-selected, consecutive group of 27 patients (39 hips) with rheumatoid arthritis. Clinical and radiological analyses were performed in 27 hips, 17 patients (mean age at surgery 45 years) after a mean of 12 years. The postoperative Harris hip score was excellent for 14 hips, 9 hips were rated as good and 4 hips were fair or poor. No stem had to be revised for aseptic loosening. Proximal stress shielding was observed in 26 hips (96%); heterotopic ossification was present in 11 hips (41%). Six hips required revision of the acetabular component. With uncemented tapered femoral fixation excellent 12-year results are achieved in patients with rheumatoid arthritis.

Type-VI collagen is an integral part of the extracellular cartilage matrix. However, the exact amounts of type-VI collagen in normal and osteoarthritic human cartilage still are not known. In this study, we describe an inhibition enzyme-linked immunosorbent assay that was developed to quantitate type-VI collagen epitopes found in guanidinium chloride extracts from normal and osteoarthritic human cartilage. In 31 cartilage samples from various localizations of healthy adult human knees, type-VI collagen epitopes accounted for approximately 0.40% of the total collagen content. Interestingly, type-VI collagen epitopes increased about 4-fold in osteoarthritic cartilage. A statistically significant increase of type-VI collagen epitopes was found during early stages of the disease, with only a superficial roughening of the cartilage surface and a loss of proteoglycans. Thus, these findings indicate that type-VI collagen is a minor component of normal human articular cartilage and that the amount of type-VI collagen epitopes increases significantly during early stages of osteoarthritis.

Type‐VI collagen is an integral part of the extracellular cartilage matrix. However, the exact amounts of type‐VI collagen in normal and osteoarthritic human cartilage still are not known. In this study, we describe an inhibition enzyme‐linked immunosorbent assay that was developed to quantitate type‐VI collagen epitopes found in guanidinium chloride extracts from normal and osteoarthritic human cartilage. In 31 cartilage samples from various localizations of healthy adult human knees, type‐VI collagen epitopes accounted for approximately 0.40% of the total collagen content. Interestingly, type‐VI collagen epitopes increased about 4‐fold in osteoarthritic cartilage. A statistically significant increase of type‐VI collagen epitopes was found during early stages of the disease, with only a superficial roughening of the cartilage surface and a loss of proteoglycans. Thus, these findings indicate that type‐VI collagen is a minor component of normal human articular cartilage and that the amount of type‐VI collagen epitopes increases significantly during early stages of osteoarthritis.