These results implicate SOST in regulating the OA disease processes, but suggest opposing effects by promoting disease-associated subchondral bone sclerosis while inhibiting degradation of cartilage.

Both groups showed comparable good to excellent clinical and radiologic outcomes at final follow-up. However, the PECA group had significantly less pain in the first 6 weeks following surgery. Level of Evidence Level II, prospective comparative study.

Objective. To explore the involvement of proteaseactivated receptor 1 (PAR-1) and PAR-2 in the pathologic processes of osteoarthritis (OA) and to identify the cells/tissues primarily affected by ablation of PAR-1 or PAR-2 in mice.Methods. OA was induced in the joints of wildtype (WT), PAR-1 ؉/؉ , PAR-1 ؊/؊ , and PAR-2 ؊/؊ mice by destabilization of the medial meniscus (DMM), and scores of histologic features (cartilage aggrecan loss and erosion, subchondral bone sclerosis, osteophytes, and synovitis) were compared at 1, 4, and 8 weeks post-DMM. The effects of PAR ablation on cartilage degradation and chondrocyte metalloproteinase expression/ activity were studied in cultures of mouse femoral head tissue with or without interleukin-1␣ (IL-1␣). At 1 week post-DMM, synovial expression of cytokines and metalloproteinase genes was measured by reverse transcription-polymerase chain reaction, and populations of inflammatory cells were quantified by flow cytometry.Results. Deletion of PAR-2, but not that of PAR-1, in mice significantly delayed the progression of cartilage damage and inhibited subchondral bone sclerosis following DMM. There was no inhibitory effect of PAR-1 or PAR-2 ablation on IL-1␣-induced cartilage degradation or chondrocyte metalloproteinase expression/activation. A low but significant level of synovitis persisted in mice subjected to DMM compared to that in control mice subjected to sham surgery, but no differences between the genotypes were seen 4 or 8 weeks post-DMM. One week after DMM, increased synovial expression of proinflammatory cytokines and metalloproteinase genes, along with increased levels of CD4؉ T cells, inflammatory monocytes, and activated macrophages, were seen in all genotypes. However, there was a significant reduction in the percentage of activated macrophages in PAR-2 ؊/؊ mice compared to PAR-1 ؊/؊ and WT mice.Conclusion. Deletion of PAR-2, but not that of PAR-1, results in a significant decrease in DMMinduced cartilage damage. The chondroprotection in PAR-2 ؊/؊ mice appears to occur indirectly through modulation of extracartilaginous events such as subchondral bone remodeling and synovial macrophage activation, rather than through alteration of chondrocyte catabolic responses.The synovial joint is an "organ" with communication and interdependence between the component tissues and cells necessary for maintenance of normal articular function (1). Osteoarthritis (OA) is the most common arthropathy, and although progressive loss of articular cartilage is pathognomonic, there are varying

Comparatively good outcomes were observed in the short to intermediate term after reverse shoulder arthroplasty in patients with rheumatoid arthritis. However, surgeons should be aware of the risk of intraoperative and postoperative fractures in this patient group.

Various cell lines of human synovial fibroblasts derived from synovium obtained at the time of biopsy or total joint-replacement surgery have been established. The synthesis of 3H-labelled hyaluronic acid (HA) in these cells has been determined, and the effects of adding HA of varying molecular size to the cultured cells examined. The results obtained clearly show that the in vitro synthesis of HA by these cells is influenced by the concentration and molecular weight (MW) of the HA in their extracellular environment. Synovial fibroblasts derived from an osteoarthritic joint demonstrated the most marked response on exposure to exogenous HA, showing a stimulation of HA synthesis with preparations of weight-average molecular weight (Mw) greater than 5 X 10(5) in a concentration dependent manner. HA preparations with Mw less than 5 X 10(5) showed little or no effect except at high concentrations where a suppression of biosynthesis was observed. A model to explain these findings is proposed.

No abstract

Lumbar IVDD was reproducibly induced with a 6 × 20 mm(2) annular lesion, with focal dysregulation of MMP gene expression, cell cloning in the inner AF, loss of NP aggrecan, and disc height. Loss of aggrecan from the NP was not attributable to increased proteolysis in the interglobular domain by MMPs or ADAMTS.

Introduction The small leucine-rich proteoglycans (SLRPs) modulate tissue organization, cellular proliferation, matrix adhesion, growth factor and cytokine responses, and sterically protect the surface of collagen type I and II fibrils from proteolysis. Catabolism of SLRPs has important consequences for the integrity of articular cartilage and meniscus by interfering with their tissue homeostatic functions.