The role of RANKL/RANK/OPG system in the canine model of hip periprosthetic infection osteolysis.

PURPOSE: We aimed to investigate whether the RANKL/RANK/OPG system is associated with the incidence of periprosthetic osteolysis with septic loosening, and to investigate the differences of RANKL/RANK/OPG system expression in synovial fluid surrounding the normal and septic loosening hip prosthesis in canine models. METHODS: Twelve healthy adult mongrel canines were divided into two groups: experimental and control. Femoral head and stem replacements were conducted on the right side in both groups. The experimental group received the bacteria fluid intra-articular injection and the other group received the same amount of saline in the same day. The synovial fluid samples were gathered at the 1st, 2nd, 4th, 8th, 12th, 16th and 19th week after the bacteria fluid intra-articular injection for enzyme-linked immunosorbent assay (ELISA), the expression of the RANKL/RANK/OPG system. RESULTS: Surgery on all animals was successful. Two dogs were excluded from the analysis of the result because of a surgery infection or death. The ELISA of the synovial fluid revealed that the ratio of RANKL/OPG showed a significant upward trend (p≤0.05) with time in the test group but the ratio of RANKL/OPG in the control group changed slowly over time (p>0.05). The ratio of RANKL/OPG value between the test and control group showed a significant upward trend, but had no statistical difference (p>0.05) over time. CONCLUSIONS: It could be concluded that the RANKL/RANK/OPG system is correlated with the incidence of periprosthetic osteolysis with septic loosening. Consequently, imbalance RANKL/RANK/OPG system was related to periprosthetic osteolysis with septic loosening.

Effect of morselized bones on binding of the canine hydroxyapatite-coated femoral stem.

BACKGROUND: Non-cement femoral stems are recognized in clinical use, but there are still some problems. The aim of this research was to make non-cement femoral stems to be press-fit with the medullary cavity. METHODS: Twenty-four healthy adult mongrel dogs were randomly divided into experimental and control groups. In the right hip joint, an artificial femoral bone replacement surgery was conducted. For the experimental group, the replacement surgery of hydroxyapatite (HA)-coated femoral stems was done, while autogeneous morselized bone was implanted into the medullary cavity. For the control group, morselized bone was not implanted. At postoperative 1, 3, 6 months, a test for interfacial shear characteristics was conducted in the MTS810 Tester. The comparison between the two groups' bone-prostheses in shear strength for their interface from shearing destruction was made. A histological observation to check prosthesis-bone interface contact ratios and bone growth was carried out. RESULTS: For the experimental group, shear strength was 0.317 MPa in 1 month, 1.447 MPa in 3 months, and 1.621 MPa in 6 months. For the control group, shear strength was 0.195 MPa in 1 month, 1.023 MPa in 3 months, and 1.483 MPa in 6 months. The difference was statistically significant. Stereomicroscope-based observation showed that the number of trabecular bones in the experimental group was larger than that of the control group, and bone growth of the former group was better than that of the latter group. Inverted microscopic observation showed that the binding degree between the prosthesis and trabecular bone of the experimental group was higher than that of the control group. Comparatively, the experimental group's trabecular bone had more stromal cells. CONCLUSIONS: The morselized bones can effectively improve the biological bonding strength and bone-contact ratios in the short term for the HA-coated femoral stem and accelerate the bonding process. The use of morselized autogenous bones played a good role in bone in-growth of the femoral bone stem surface.

Study on the impact of morselized bones on biological binding of HA-coated femoral stem in dogs.

The impact of the dog's morselized autologous bone implantation into femoral medullary cavity on binding in the hydroxyapatite-coated femoral stem prosthesis-bone interface was studied. Twenty-four adult mongrel dogs were divided into 2 groups: experimental and control. The experimental group's medullary cavity was filled with morselized autologous bone. Artificial femoral-stem replacements at the right side were then carried out. At 1, 3, and 6 months postoperatively, computed tomography (CT) values reflecting changes in bone density were measured. A histological observation to check prosthesis-bone interface contact ratios and bone growth was conducted. Analysis of radiographs of slices was made using Interactive Data Language (IDL; ITT Visual Information Solutions, Boulder, Colorado) software. Results showed that the experimental group fared better than the control group, and the difference was statistically significant (P<.05). Stereomicroscope-based observation showed that the number of trabecular bones in the experimental group was larger than that of the control group, and bone growth of the experimental group was also better than that of the control group. Inverted microscope observation showed that the binding degree between prosthesis and trabecular bone of the experimental group was higher than that of the control group. Comparatively, the experimental group's trabecular bone had more osteogenic cells. The binding between morselized autologous bone and hydroxyapatite-coated femoral stem prosthesis can improve direct bone-contact ratios, and the experimental group's number of newly formed trabecular bone was significantly larger than that of the control group.