Post-traumatic chylous knee effusion.

Chylous joint effusion is a rare condition in which synovial fluids containing large amounts of lipids take on a milky appearance as a result. We report on a 19-year-old male patient with posttraumatic chylous knee effusion. Several days after striking his knee against the ground because of a traffic accident, his left knee showed obvious swelling. Aspiration of his knee was performed, yielding 70ml of purulent-appearing fluid. To distinguish this condition from purulent or tuberculosis arthritis, arthroscopic biopsy and debridement were performed. Arthroscopic examination visualized distinctive yellow-white soft lesions covering much of the joint capsule, resembling a cobweb. Tissue cultures for bacteria were negative. Pathologically, we identified clusters of xanthoma cells with fibrin exudation due to disruption of the synovium and intra-articular fat pad necrosis. Centrifuging the aspiration fluid yielded a thick creamy lipid layer as the supernatant. A fresh drop preparation showed that the specimen contained innumerable fat globules, which stained red with oil red O stain. The patient was able to walk without difficulty or further swelling of his knee at the end of the second postoperative week. Posttraumatic chylous effusion is self-limited. Purulent arthritis or tuberculosis arthritis, however, should still be the presumptive diagnosis in such cases. Arthroscopic irrigation and debridement should be considered for these traumatic cases to confirm diagnosis and to speed up recovery.

Effects of autologous platelet-rich plasma on cell viability and collagen synthesis in injured human anterior cruciate ligament.

BACKGROUND: Platelet-rich plasma is a fraction of plasma in which platelets are concentrated. It is reported to represent a source of multiple growth factors that promote tissue repair. In anticipation of the eventual testing of platelet-rich plasma in anterior cruciate ligament (ACL)-deficient patients, we examined the effect of autologous platelet-rich plasma on human ACL cell function in vitro. METHODS: Fresh blood and ACL remnants were obtained from four patients who underwent ACL reconstruction surgery. Platelet-poor plasma and platelet-rich plasma were prepared from the blood samples. The concentrations of various growth factors in each preparation were tested with use of enzyme-linked immunosorbent assays. Isolated ACL cells were cultured in the presence of 5% fetal bovine serum, 5% platelet-poor clot releasate, 5% platelet-rich clot releasate, or 10% platelet-rich clot releasate. Platelet-rich plasma and platelet-poor plasma releasates were applied to the ACL cells from the same patient autologously. Cell viability and collagen synthesis in each group were analyzed, and semiquantitative gene-expression assays for type-I and III collagen were also performed. RESULTS: The concentrations of the main growth factors (transforming growth factor-beta, platelet-derived growth factor, epidermal growth factor, and vascular endothelial growth factor) were much higher in platelet-rich clot releasate than in platelet-poor clot releasate. In vitro treatment of ACL cells with platelet-rich clot releasate resulted in a significant increase in cell number compared with platelet-poor clot releasate. Total collagen production by the platelet-rich clot releasate-treated cells was significantly higher than that of the platelet-poor clot releasate-treated cells only because of enhanced cell proliferation. There was no significant effect of platelet-rich clot releasate treatment on gene expression for type-I collagen, but expression of type-III collagen was significantly enhanced by the treatment with platelet-rich clot releasate. CONCLUSIONS: These results suggest that autologous platelet-rich plasma can enhance ACL cell viability and function in vitro.

In vivo maturation of scaffold-free engineered articular cartilage on hydroxyapatite.

Tissue engineering is a promising approach, not only for cartilage, but also for osteochondral repair. Recent studies have demonstrated that scaffold-free cartilaginous tissue can be engineered using the alginate-recovered-chondrocyte (ARC) method. This method has also been applied to form osteochondral tissue using bovine articular chondrocytes and coralline hydroxyapatite (HA). The purpose of this study was to test whether osteochondral tissue, fabricated in vitro using the ARC method combined with a block of HA, would undergo maturation in vivo using a subcutaneous model in immunodeficient mice. Articular chondrocytes were isolated from the cartilage of New Zealand white rabbits and cultured in alginate beads. The cells with their associated matrix were recovered by dissolving the alginate beads with a sodium citrate buffer, resuspended in media and seeded onto a porous HA block. After 4 weeks of culture, some samples were analyzed, and others were implanted into subcutaneous pockets in nude mice. The analysis involved removing the cartilage portion of the de novo-formed ARC-HA graft and performing biochemical and histological examinations. Some samples were subjected to nondecalcified histology. Histological and immunohistochemical analyses of cartilaginous tissue were performed at 0, 2, 4, and 8 weeks after implantation. Biochemical characteristics were examined at 0, 4, and 8 weeks. The size and shape of the implanted ARC osteochondral tissue changed with time. The histological and immunohistochemical examination of the tissue revealed that it contained a cartilage-like matrix that stained strongly with Toluidine blue and for collagen type II. The proteoglycan (PG) content had increased significantly at 4 weeks from baseline. However, by 8 weeks, the PG content had decreased from 4 weeks. The results presented here represent a possible approach to form a tissue-engineered osteochondral implant. Further studies are needed to improve biomechanical properties of the osteochondral implant to be suitable for surgical transplantation.