| Massive reconstituted bovine xenograft(MRBX) reinforced with antibiotics has grown promising in the treatment of large segmental infected bony defect. Local drug delivery system(LDDS) is mainly concerned in the preparation of the type of graft material. Many materials can be used as carriers of LDDS, but there still exist some disadvantages. It is advised that a new form of LDDS should be drafted with the combination of their strong points. In this investigation, CPC drug core reinforced with BMP and Gentamycin is embedded in MRBX, then CPC-MARBX is formed, which features fine drug delivery, osteoconduction and osteoinduction capability. Because of the enlarged contact area of CPC with body fluid and introduction of BMP, degeneration of CPC can therefore be accelerated.I Preparation of CPC-MARBX and microstracture and mechanical features Objective To investigate the microstructureand mechanical features of CPC-MARBX Method CPC incorporated with BMP and Gentamycin was perfused in the holes of MRBX and. CPC-MARBX was obtained after CPC solidification was reached. Mechanical properties in terms of anti-compression and anti-tension were measured. Scan electronic microscopy was applied to measure the variation between the incorporated CPC and the pure CPC. Results CPC-MARBX could be relatively easily made under normal temperature and pressure with no reference to special chemical agents. Scan electronic microscope found less crystals in the incorporated CPC than in the pure CPC. Mechanical measurement showed increased anti-compression and umimpaired anti-tension capability. Conclusion CPC-MARBX is readily available with improved mechanical properties and reduced crystallization.II In vitro and in vivo drug delivery test of CPC-MARBX Obejective To investigate drug delivery capability of CPC-MARBX in vitro and in vivo Method In vitro test was applied to assess the drug delivery capability, in which CPC-MARBX was immersed in PBS, in the in vivo test CPC-MARBX was implanted in the dorsal muscle pouch of the rabbit. The drug concentration in PBS, animal blood and surrounding soft tissue of the CPC-MARBX in the muscle pouch was measured at 1, 2, 5, 10, 15, 20, 25, 30 and 35d with the same setting. Results In vitro drug delivery test indicated that the drug concentration even after 25d remained above the MIC. In vivo test showed that it was extended 30d while blood level was not increased Conclusion CPC-MARBX features fine drug delivery capability.III CPC-MARBX applied to repair large segmental infected bony defect Objective To investigate the therapeutic effect of CPC-MARBX on large segmental infected bony defect. MethodLarge segmental infected bony defect of the femur in the rabbit model was created to test the repairing capability of CPC-MARBX. In the experimental group the bony defect was replaced by CPC-MARBX while in the control group dissected bone block was reimplanted in the original position. The animal was subjected to radiographic, histological, bacteriological and bone density examination at 4, 8, 16 and 24w. The general condition was observed for all the time. Results In CPC-MARBX group, we didn't find adverse influence such as anorexia, reduced activity and inflammation sign, etc. X-ray manifested progressively increasing bony callus around the graft throughout the initial 8 weeks, the femur healing occured at 24w. The animal could walk after 4w, external fixation was then removed and normal activity was restored after 8w. No inflammation manifestation could be seen on the incision and germiculture of the graft was negative. Abundant chondral tissue had grown into CPC-MARBX after 4w, CPC had shown to be degenerated dramatically after 8w while new bone tissue grew more. Bony defect could be repaired and CPC could be degenerated completely at 24w. Bone density of experimental side was lower than the normal before 8w(P<0.05), but not different after 16w(P>.05). In the control group purulent exudation was observed, the rear limb was disabled. The autograft remained nonuni...
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