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Histologic and immunostaining analyses were performed on articular cartilage/subchondral bone biopsy specimens overlying MRI‐detected bone bruises in 12 patients with anterior cruciate ligament (ACL) tears. Staining with toluidine blue for proteoglycan revealed loss of staining from the superficial portion of the articular cartilage. Immunostaining for cartilage oligomeric matrix protein (COMP) showed an increased staining in the superficial matrix of the articular cartilage. Using polyclonal antisera against COMP, the authors performed a competitive enzyme‐linked immunosorbent assay (ELISA) on the synovial fluid from the injured and uninjured knees. There was an approximately 10‐fold higher synovial fluid COMP levels in injured knees. The COMP levels were greater in those patients who had synovial fluid samples harvested closer to the date of initial injury. Western blot analysis of the synovial fluid showed an increased presence of COMP degradation fragments from injured knees. These results are indicative of a significant injury to the articular cartilage, and may represent preclinical posttraumatic osteoarthritic lesions. © 2001 Orthopaedic Research Society. Published by Elsevier Science Ltd. All rights reserved.

To determine which of two currently used techniques for the treatment of periprosthetic femoral shaft fractures provides the greater fixation rigidity and strength.

The osteochondrodysplasias are a heterogeneous group of disorders characterized by abnormal growth and remodeling of cartilage and bone, affecting from 2 to 4.7 per 10,000 individuals. Most osteochondrodysplasias are heritable and many have elaborate patterns of genetic transmission. Affected individuals generally require management by multidisciplinary teams of specialists. In this review, we divide the osteochondrodysplasias into groups based on their genetic relationships, including mutations in various types of collagen, fibroblast growth factor, cartilage oligomeric matrix protein, parathyroid hormone receptor, the diastrophic dysplasia sulfate transporter, enzymes such as steroid sulfatases, transcription factor SOX9, and a cysteine proteinase, cathepsin K. We describe the major osteochondrodysplasias, define their causes and clinical manifestations, and provide the orthopaedic surgeon with an understanding of the underlying molecular defects as well as the anatomical aspects of these disorders.

Synovium and cartilage from patients with osteoarthritis or rheumatoid arthritis were analyzed for expression of cartilage oligomeric matrix protein. Immunostaining of synovium with antiserum to cartilage oligomeric matrix protein demonstrated positive staining in both diseases. In osteoarthritis, there was positive staining within the synovial cells and immediately subjacent connective tissue, with less intense staining in the deeper connective tissue. In rheumatoid arthritis, there was less intense staining within the synovial cells and marked intense staining in the deeper connective tissue. In situhybridization performed with an antisense digoxigenin‐labeled riboprobe to human cartilage oligomeric matrix protein confirmed the presence of cartilage oligomeric matrix protein mRNA in the cells of the synovial lining in both types of synovium. Quantitative polymerase chain reaction with a cartilage oligomeric matrix protein MIMIC demonstrated increased cartilage oligomeric matrix protein mRNA in rheumatoid cartilage and synovium as compared with osteoarthritic cartilage and synovium, respectively; mRNA levels in rheumatoid synovium were similar to those from osteoarthritic chondrocytes. As a result of the high expression of cartilage oligomeric matrix protein from rheumatoid synovium, inflammatory synovium should be considered as a potential tissue source of cartilage oligomeric matrix protein in any investigation of biological markers of cartilage metabolism. The upregulated expression of cartilage oligomeric matrix protein in inflammatory tissues suggests its in vivoregulation by cytokines.

Production of nitric oxide by solid tumors may have important ramifications regarding tumor growth and potential metastasis. This study demonstrated that the chondrosarcoma of the Swarm rat has upregulated mRNA for inducible nitric oxide synthase and produces nitric oxide. These results were confirmed by (a) the, presence of a 4.4‐kb band of mRNA detected by Northern blot using a probe for inducible nitric oxide synthase, (b) a 133‐kDa band of prothein that was detected with either a polyclonal or monoclonal antibody to the inducible nitric oxide synthase of the murine macrophage. and (c) the detection of nitrites from the culture medium of freshly cultured, isolated chondrosarcoma cells. This study showed that the expression of inducible nitric oxide synthase and the production of nitric oxide by the tumor can be increased by stimulation with endotoxin lipopolysaccharide and can be inhibited by inducible nitric oxide synthase inhibitors (L‐N(g)‐monomethyl arginine and aminoguanidine). Immunostaining confirmed the presence of inducible nitric oxide synthase within the tumor cells and appeared to localize the enzyme to the cytoplasm of the cells. A human chondrosarcoma was also shown to have an upregulated inducible nitric oxide synthase by both the detection of mRNA for inducible nitric oxide synthase and the presence of nitrites from the culture medium of the tumor in organ culture. Because the chondrosarcoma of the Swarm rat is a well differentiated solid tumor that rarely metas‐tasizes, nitric oxide may be produced by the tumor to promote local growth by effects on vascular supply.

Cartilages contain a common set of macromolecules, such as aggrecan, link protein and collagen II, but their relative proportions may vary to produce tissues with different biochemical and physical properties. Further, there exist matrix proteins that are present only in a subset of cartilages and which may be involved in the fine tuning of the properties of the matrix. Cartilage contains a number of proteins, that are also present in other tissues as well as a number of proteins with a more restricted tissue distribution which may even be specific for cartilage. Many proteins, such as link protein (Gardell et al. 1980), aggrecan (Wong et al. 1992) and cartilage oligomeric matrix protein (DiCesare et al. 1994) are found more widely distributed than initially assumed, albeit often at very low concentrations.

Cartilage oligomeric matrix protein (COMP) (Hedbom et al. 1992), a pentameric chondrocyte-binding glycoprotein, and cartilage matrix protein (CMP) (Paulsson and Heinegård 1982), a trimeric glycoprotein, have been characterised from different cartilages.