From July 1998 to May 2000, 31 cases of lumbar spondylolisthesis accompanied with lumbar stenosis were treated with spinal cord decompression, autograft interbody fusion and fixed by Dyna lok system. All the patients were followed up for 6 to 28 months, averaged 12 7 months. 29 of the 31 patients were recovered completely. 2 cases of cauda equina were recovered within 2 months. Lowback pain remained in 1 case of multi segements spondylolisthesis which had been fixed for 3 vertebrae. 1 patient accompanied with cervical spinal stenosis had some residual claudication. In conclusion, spondylolisthesis fixed with the Dyna lok system can achieve a satisfactory result.

OBJECTIVE: To summarize the biocharacteristics, separation and purification as well as the culture technique of bone marrow mesenchymal stem cell, which has the potentiality of multiple cellular differentiations, locatedinduced differentiation of bone and cartilage, cellular carrying tray and application in bone tissue engineering.DATA SOURCES: Relative articles were retrieved through Medline database according to the key words of "mesenchymal stem cell, tissue engineer" in English between January 1990 and December 2004. Meanwhile,relative articles were also retrieved in Chinese journal full-text database and Wanfang database with the same key words in Chinese between January 1994 and December 2004.STUDY SELECTION: Articles were retrieved first to select those references which were related to the aspects of biology, isolation and culture of mesenchymal stem cell in tissue engineering. Representative and lated references were included; however, researches on non-bone tissue engineering and repetitive studies were excluded. The rest of articles were looked up for their full text.DATA EXTRACTION: There were 78 articles on mesenchymal stem cell in tissue engineering. Among them, 31 papers were included; the otherbut 47 papers including 13 articles of similar contents and 34 studies on nonbone tissue engineering were excluded.DATA SYNTHESIS: Mesenchymal stem cell mainly existed in bone marrow and could differentiated into multiple tissue cells and increase in vitro.① There were three methods for separation, purification and culture of mesenchymal stem cells: density gradient centrifugation, flow cytometry and adherent screening method. Other scholars obtained cell strain of mesenchymal stem cell through single-cell cloning technique, but this way was more difficult to obtain multiple seed cells. At present, density gradient centrifugation was widely used. ② Mesenchymal stem cell could differentiate into bone cells and cartilae cells through adding inductor into eligible culture medium. Ideal scaffolds could carry and retain the vitality of cells, support rapid endogeny of vessels and be benefit for observing new bone formation under X ray. New bone might be absorbed and replaced in bone rebuilding and form or increase conductive bridging of host bone. Functions of differentiated cells could be maintained by the interaction between scaffolds surface and cells, and the histocompatibility was well. ③ Mesenchymal stem cell was an kind of ideal target cells for gene therapy. It could shift growth factor or cytokine and express foreign protein after multiple desintegration in vitro. It was successful in bone tissue engineering.CONCLUSION: Modern tissue engineering which is presented by stem cells develops quickly at present, but tissue engineering of mesenchymal stem cell starts just now. Bone marrow mesenchymal stem cell is characterized by easily materializing, potentiality of multiple tissue differentiation, stable genetic background, non-rejection in implant button and high proliferation. All properties determine that it will be a useful thing in cell and gene therapy as well as tissue engineering.

BACKGROUND: Acetabular malignant tumor reconstruction is to obtain pelvic stability and lower limb walking function to excise the tumor at safe margin.Excision range has been evaluated by MRI,CT,X-ray,which are subjective and lack preoperative design.Computer-aided three-dimensional reconstruction can evaluate tumor erosion range from all planes to accurately excise the tumor.OBJECTIVE: To evaluate the value of computer aided design in the treatment of acetabular malignant tumor.METHODS: One case with acetabular hemangiosarcoma was checked with lamellar CT scanning,which acquired some two-dimensional data in disease area.The three-dimensional reconstruction of anatomical model,design of cutting bone extent,design of individual prosthesis and sham operation were made by computer.Based on computer aided design proposal,acetabular tumor was resected,pelvic ring and right hip articulation were reconstructed with allogeneic semi-pelvis and individual total hip replacement.RESULTS AND CONCLUSION: The patient began to non-weight bearing walk with double crutches 2 months after operation.At6 months,the patient walked normally.The right hip joint motion was good with no pain.Postoperative X-ray film displayed individual prosthesis matched to pelvis.The patient fell a little numbness of skin in the lateral of right hip.No phlebothrombosis,prosthesis loosening or dislocation was found.Computer aided design has a good perspective of application in the treatment of acetabular malignant tumor.Individualized treatment can improve operation accuracy,reliability,convenience and curative effect.