Presently,studies of onset,development and tumor drug resistance of osteosarcoma were few.Further studies on tumor animal models can provide a promising basis for treating osteosarcoma.Commonly used animal models of osteosarcoma include mouse,rat,rabbit and dog.Organs of rats are similar to human,so does genotype.Dogs can spontaneously develop osteosarcoma,which is similar to human,and are frequently used as spontaneous tumor models.However,there are some differences in biological features,pathogenic mechanism and histology.With the development of studying,there will be more and more new animal models in accordance with human osteosarcoma characteristics.The present study served to review methods of establishing models,characteristics and detailed application of animal models of osteosarcoma.

Chordoma is a rare low and moderate-grade malignant tumor originated in the embryonic period residual notochord tissue.Due to its critical location, local aggressive nature, and high recurrence, chordoma is not sensitive to radiotherapy and chemo-therapy with poor prognosis .Surgery is the main treatment method .Here we present a review focusing on basic and clinical research progress of chordoma .

Osteosarcoma is the most common aggressive malignancy of bone.Recent studies have discovered that exosomes can mediate intercellular transfer of biologically active molecules such as RNAs, dsDNA, and miRNAs.The specific membrane struc-ture and contents of exosomes are widely engaged into the exchange of material and information among tumor cells, which play an im-portant role in regulating the tumor microenvironment of osteosarcoma, mediating the expression of Wnt/β-catenin, TGF-βsignaling and inducing tumor cell immune escape.Exosomes derived from osteosarcoma cells with antigen-presenting cells cause significant anti-tumor effect by activating the immune response.Research on exosomes has therefore opened up a new avenue for treatment of osteosar-coma.In this article we review the role of exosomes in pathogenesis of osteosarcoma and its potential application on diagnosis and treat-ment of osteosarcoma.

Acute traumatic central cord syndrome ( ATCCS) is the most common incomplete cervical spinal cord injury .Its di-agnosis mainly depends on the mechanism of injury , physical signs and imaging examination .The main treatment method is conserva-tion or surgery.Here we reviews the progress of its pathogenesis , pathophysiological changes , and surgical treatment advances .

Intervertebral disc degeneration is one of the orthopedic common diseases , its complex physiopathological changes are regulated by many factors .The matrix metalloproteinases ( MMPs) and its regulatoryl factors play a very important role , and the factors that affect the role of MMPs in intervertebral disc degeneration interact with each other .So MMPs have gradually become one of the hot spot of intervertebral disc degeneration in recent years .In this paper , we first analyze the factors that cause the degeneration of intervertebral disc .Then we summarize the relationship between the expression of MMPs and the degeneration of intervertebral disc ac -cording to the different function of MMPs members in the family .Finally we state that MMPs can have an effect on the degeneration of intervertebral disc by the regulation of gene polymorphism and the related factors .

s:Bone allografts have been successfully used in repairing bone defect caused by tumor, infection or trauma. The mechanism of bone-healing of allografts has been widely studied. The article reviews the factors affecting the bone-healing of allografts.

Ewing's sarcoma is a kind of bone and soft tissue tumor which is highly invasive and mainly occurres in children and adolescents.In recent years,combined chemotherapy,surgery and radiation therapy in treatment of Ewing's sarcoma,patients' prognosis and life quality have been significantly improved.However,over the past 20 years,the treatment of Ewing's sarcoma entered the platform period.The 5-year overall survival rate remained at 55％-75％.Multiple metastasis and recurrence are the main factors of poor prognosis and death.Chemotherapy,radiotherapy and molecular targeted therapy are still the main methods for the treatment of Ewing sarcoma.The side effects,drug resistance and the use of the combination regimen of antitumor drugs have been plaguing the clinical workers.In order to improve the efficacy of chemotherapy drugs and reduce the toxic side effects,Multi-disciplinary and multi-center clinical studies on Ewing's sarcoma patients who suffered from local control or recurrence have been launched by Domestic and European and American countries.As an important supplementary mean for the treatment of Ewing's sarcoma,patients often appear a series of complications after radiotherapy,including the risk of local damage or secondary tumors.Therefore,it is necessary to further clarify the indications of radiotherapy and the timing of preoperative and postoperative radiotherapy.The specific chromosome translocation and the expression of the fusion gene EWS/FLI 1 have been found in Ewing sarcoma.Nevertheless,the mechanisms that drive tumor relapse and metastasis remain unknown.Molecular targeted therapy can be used to inhibit tumorigenesis and progression by regulating the upstream or downstream target genes of EWS/ FLI1.In conclusion understanding of the current treatment status of Ewing's sarcoma,results of multi-center clinical trials and theory of genomics research will contribute to the design of new biological therapies so as to establish individualized treatment modalities.In this paper,we present a review on the progress of Ewing sarcoma chemotherapy,radiotherapy,molecular targeted therapy and immunotherapy.

Objective The periacetabular tumor has a low rate of incidence, but its special location poses a challenge to clinical treatment.The aim of this study was to discuss the methods, effects, and complications of surgical treatment of periacetabular tumors. Methods We retrospectively analyzed the clinical data of 36 cases of periacetabular tumor surgically treated in our depart-ment, including 21 males and 15 females, aged 15 to 64 (45.2 ±6.3) years.Among them, there were 8 cases of benign tumor (4 ca-ses of simple bone cyst, 1 case of desmoplastic fibromas, 1 case of osteofibrous dysplasia, and 2 cases of hemangioma) and 28 cases of malignant tumor (5 cases of osteosarcomas, 12 cases of chondrosarcomas, 2 cases of giant cell tumor of the bone, 1 case of malignant chondroblastoma, 2 cases of malignant fibrohistiocytoma, and 5 cases of metastatic tumor of the bone).The benign cases received sim-ple tumor resection plus bone graft and steel plate system internal fixation, while malignant cases underwent reconstruction by combined pedicle screw fixation system with bone cement. Results No patients died perioperatively and controllable complications occurred in 5 cases after operation.All the patients were followed up for 5 to 96 months except for 1 case of benign tumor.None of the benign cases experienced recurrence, and all of them achieved normal hip function.Lung metastases occurred in 10 malignant cases (4 cases of os-teosarcomas and 6 cases of chondrosarcomas) , who died of respiratory failure, and the other 18 remained tumor-free after surgery.Of the 2 patients with malignant fibrohistiocytoma, 1 died 2 years postoperatively and the other survived with tumor.Neither local recur-rence nor lung metastasis was found in the patients with chordoma and malignant chondroblastoma till the end of follow-up.The 5 pa-tients with metastases died within 3 years after operation.At 3 months after surgery, the Harris scores after total hip replacement were >90 in the 7 benign cases, 70-79 in 9 malignant cases, and <70 in the other 19 malignant cases. Conclusion For the treatment of malig-nant tumors, reconstruction by combined pedicle screw fixation system with bone cement does not affect the general daily activities of the pa-tients.Preoperative embolization of the internal iliac artery can reduce bleeding and improve operation safety, and measures should be taken to minimize postoperative complications.

Objective To explore the operation of C-type osteotomy for reduction of prominent zygomatic complex. Methods Based on the severity and characteristics of prominent zygomaitc complex, Ctype osteotomy was designed for the malar complex reduction by using oral and minor pre-auricular approaches under general anaesthesia. Two paralleled osteotomic lines of C-type were marked from zygomatic alveola to the conjunction of lateral orbital margin and zygomatic arch through the inferio-lateral edge of orbit. The extension of zygomatic arch reduction was determined the width of two osteotomic lines. The bone which marked lines was removed by reciprocating saw and osteotome. The zygomatic arch root was osteotomiced by pre-auricular approaches. Then, the zygomatic complex could move freely towards superior-medial position. Finally, the zygoma was fixed with titanium mini-plates. Results 12 patients with prominent zygomatic complex had been successfully operated by C-type osteotomy from July 2006 to April 2009. Of them, six cases were symmetrical and six cases were unsymmetrical. Postoperative follow-up for 4-24 months, infection was not occurred, and the scar of pre-auricular incision was not obvious. All the patients obtained positive results. Conclusion C-type osteotomy for correction of prominent zygomtic complex through intra-oral and minor pre-auricular approach is an effective surgical method and gives superior results. It preserves the intactness of maxillary sinus, prevents facial slack, and is especially effective for patients with prominent zygomatic arch.

Objective:To evaluate the clinical outcomes of patients after intensity modulated radiation therapy (IMRT) for hepatocellu-lar carcinoma (HCC) with portal vein tumor thrombosis (PVTT) or inferior vena cava tumor thrombosis (IVTT). Methods:A registry data-base of 41 patients treated with IMRT for HCC with PVTT or IVTT in Radiotherapy Center of No.3 Hospital of Beijing Chinese People Armed Police Forces between January 2013 and May 2015 were analyzed retrospectively. The biological effective dose of radiation was ranged 48-94Gy. Short-term effects and prospective efficacy were observed. Log-rank test, Cox regression were used for survival analysis and prognostic factor identification. Results: Grade 2 or higher level gastrointestinal reaction was observed in 12 patients (29.3%). Hematological toxicity was observed in 11 patients (26.8%), and radiation-induced liver disease was observed in 6 patients (14.6%). We found that 29.3%of patients achieved a complete response and 31.7%of patients achieved a partial response. The stable and progressive disease rates were 39.0%and 0.0%, respectively. Median patient survival was 11 months, and the 1-year survival rate was 34.1%. The significant independent variables associated with the overall survival included Child-Pugh grade, AFP test, and CHE lev-el. Conclusion:IMRT is a safe and effective treatment for PVTT or IVTT in patients with HCC.