Determination of silver content in silver-loaded coral hydroxyapatite in relation to the biocompatibility / 南方医科大学学报

<p><b>OBJECTIVE</b>To determine the amount of silver in silver-loaded coral hydroxyapatite (Ag(+)-CHA) bone substitute and its impact on the biocompatibility of this material with mouse embryonic osteoblast cells.</p><p><b>METHODS</b>Ag(+)-CHA was prepared by immersing coral hydroxyapatite in a serial concentration of silver nitrate solutions. The amount of silver in the prepared Ag(+)-CHA was measured by inductively coupled plasma atomic emission spectrometry (ICP-AES). The viability of MC3T3-E1 cells incubated with Ag(+)-CHA was measured by MTT colorimetric assay, and the cell growth and morphological changes were observed by inverted phase-contrast microscope and confocal laser scanning microscope.</p><p><b>RESULTS</b>The amount of silver loading in the bone substitutes prepared by immersion in 1×10(-2), 1×10(-3), 5×10(-4), 10(-4), 8×10(-5), and 5×10(-5) mol/L silver nitrate solutions were 4127.67∓47.35, 167.90∓11.00, 83.42∓4.51, 30.20∓2.32, 22.39∓4.09, and 15.11∓0.55 µg/g, respectively. A low silver content in the material (prepared with silver nitrate solution of less than 8×10(-5) mol/L) showed no significant inhibitory effect on the growth of MC3T3-E1 cells or produced noticeable cytotoxic effect. On the materials prepared with 8×10(-5) and 10(-5) mol/L silver nitrate solution, the osteoblasts displayed active proliferation similar to those incubated on materials without silver loading. The confluent cells showed a normal fusiform morphology with tight arrangement.</p><p><b>CONCLUSION</b>Ag(+)-CHA with low silver content has a good biocompability and can promote the proliferation and growth of MC3T3-E1 cells in vitro, suggesting the clinical potential of this material as a anti-infection bone substitute.</p>

Diagnosis and treatment for complicated atlantoaxial dislocation / 中华外科杂志

<p><b>OBJECTIVE</b>To explore the clinical characteristics and treatment methods for complicated atlantoaxial dislocation.</p><p><b>METHODS</b>A retrospective evaluation was done to summarize and analyze the clinical characteristics and complicated factors of 54 patients with complicated atlantoaxial dislocation who could not to be treated effectively by using conventional therapy in our hospital from February 2005 to October 2008. According to different complicated factors, different treatment methods mainly including transoral atlantoaxial reduction plate-III (TARP-III) operation, decompression procedure with deep grinding guided by computer aided design-rapid prototyping (CAD-RP), screw placement technique with CAD-RP guide plate and extensile approach surgery were performed.</p><p><b>RESULTS</b>The average follow-up period was 24 months. Among 54 cases, 48 cases achieved immediate anatomic reduction completely and 6 cases almost achieved anatomical reduction. All the compressed spinal cords were decompressed sufficiently. The decompression rate was 86.0% and the improvement rate of nerve function was 77.8%. Two cases suffered postoperative intracranial infection.</p><p><b>CONCLUSION</b>Some cases of complicated atlantoaxial dislocation can be effectively treated by using TARP-III operation, decompression procedure with deep grinding guided by CAD-RP, individualized screw placement technique with CAD-RP guide plate and extensile approach surgery.</p>