BACKGROUND: Beta-tricalcium phosphate (β-TCP)/alpha-calcium sulfate hemihydrate (α-CSH) artificial composite bone has a porous morphology and good biocompatibility, and it is helpful to improve the fusion rate in a spinal fusion model, which however has not yet been confirmed.OBJECTIVE: To investigate the preparation methods, biocompatibility and application effect of β-TCP/α-CSH composite bone in the spinal fusion model.METHODS: (1) Calcium sulfate dihydrate under certain conditions and at a proper temperature can be dehydrated to prepare α-CSH. Healthy bovine cancellous bone was decellularized, degreased and sintered under the certain condition and at the certain temperature to prepare β-TCP particles. Then, the β-TCP particles were dissolved in anhydrous ethanol, suspended, dried, and then used to prepare the β-TCP/α-CSH composite bone. Osteoblasts from the rabbit periosteum were co-cultured with the composite bone, and then cell morphology, adhesion and proliferation were observed. (2) Twenty New Zealand white rabbits were selected to make bilaterally posterolateral spinal fusion models of the multiple thoracic vertebrae, in which β-TCP/α-CSH composite bone was implanted into the left side (experimental group) and autogenous bone implanted into the right side (control group). The spinal fusion rate was compared between the two groups.RESULTS AND CONCLUSION: (1) Under the phase contrast microscope, a relatively small amount of L929 cells adhered to the composite bone after 3 days of co-culture, while the number of adherent cells became relatively dense. Under the scanning electron microscope, there were many crystalline particles on the surface of the composite bone,indicating a higher number of adherent cells on the composite bone surface. (2) The spinal fusion rate was increased at 4 weeks after implantation of β-TCP/α-CSH composite bone, which was significantly higher than that after implantation of autogenous bone (P < 0.05). (3) At 4 weeks after autogenous bone implantation, the bone trabecular bone was scarce and clumped, and newborn bone tissues and the boneless autograft bone were dominant. After 8 weeks after spinal fusion, the newborn bone tissues around the autograft were further increased. At 4 weeks after β-TCP/α-CSH composite bone implantation, there was no degradation of debris, but existed a few new bone tissues; at 8 weeks after implantation,the composite bone was surrounded by newborn bone tissues, and thickened trabecular bone and degradation of the composite bone were found. To conclude, the prepared β-TCP/α-CSH composite bone can achieve a higher fusion rate in the spinal fusion model.

Objective To evaluate the indications,techniques and effects of high speed drill assisted cervical pedicle screw-rod system in treatment of cervical interlocking dislocation.Methods A retrospective review was made on data of 13 cases of cervical interlocking dislocation undergone pedicle screw-rod fixation and reduction with assistance of high speed drills from December 2006 to July 2011.Dislocation localized in C3/4 (n =3),C4/5 (n =5),C5/6 (n =4) and C6/7 (n =1) respectively.Causes for injury contained cervical hyperextension due to traffic accidents (n =7) and a fall from the height (n =6).Two remained neurological intact,seven were combined with syndrome of central canal damage,and four had paraplegia.All the 13 cases received posterior pedicle screw fixation and reduction within 7 days after injury.Pedicle screws were implanted on adjacent segment of cervical spine with unlocking the interlocked small joints by a distraction device.Results All 13 cases obtained good reduction,including eight with complete anatomic reduction and five with 1-2 mm of vertebral slight slippage.Fifty-two screws were inserted and 49 pedicle screws were put in place except for the excursion in three pedicle screws on the postoperative radiographic and CT scans.There was no injury of spinal cord,nerve root or vertebral artery during operation.The patients showed significant improvement in sensory and motor function of the upper extremities in the follow-up of 12-36 months.One case had screw breakage at postoperative three months with no nerve symptoms.Conclusion High speed drill assisted pedicle screw-rod system is suitable for treatment of cervical interlocking dislocation,for its reduction process accords with the biomechanics and allows decompression therapy.

Objective The purpose of this study was to examine effects of Isopsoralen on the osteoblast proliferation and differentiation and find its possible molecular mechanisms for anti-osteoporosis.Methods OCT-1 cells were cultured with common methods.While growing well,cells were cultured with 3 doses(10 μg·mL-1,30u μg·mL-1 and 60 μg·mL-1)of Isopsoralen for 48 h,or with purified bone morphogenetic protein 2(BMP2)protein(50 ng·mL-1).We first determined the effect of Isopsoralen on cell proliferation by MTT assay.The real time RT-PCR was also used to quantify changes in the mRNA levels of several genes,such as BMP2,Runt-related transcription factor 2(Runx2),and Osterix(Osx).We also used the Western blot analysis to evaluate the expression of Runx2 and Osx proteins.At last we used the BMP2loxp/loxp mice to isolate the primary calvaria osteoblasts,cultured with Isopsoralen of the best dose for 48 h after the in vitro conditional gene knockout technology,and tested the gene expressions of Runx2 and Osx.And the alkaline Phosphatase(ALP)staining was also performed.Result Isopsoralen(10 μg·mL-1)can promote osteoblast proliferation obviously.From the real time RT-PCR analysis,Isopsoralen can enhance the BMP2 mRNA levels,the effect of 10 μg·mL-1 was the best,and 30 μg·mL-1 followed.In addition,we found that Isopsoralen(10 μg·mL-1)can enhance the Runx2 mRNA levels significantly.We also found that lower doses of Isopsoralen can enhance the Osx mRNA levels,the effect of 30 μg·mL-1 was the best,and 10 μg·mL-1 followed.From the Western blot analysis,low doses of Isopsoralen(10 μg·mL-1 and 30 μg·mL-1)can stimulate the expression of Runx2 protein.Besides,three doses of Isopsoralen can stimulate the expression of Osx protein,and the effect of 10 μg·mL-1 and 30 μg·mL-1 are better.Finally,the results of in vitro conditional gene knockout experiment showed that the overexpression of Runx2 and Osx genes in osteoblasts,as well as ALP staining,induced by Isopsoralen are BMP2 dependent.Conclusions In this study,we firstly demonstrate that Isopsoralen can stimulate osteoblast proliferation and differentiation by mediating BMP2/Runx2/Osx signaling pathway.