Objective To introduce a new spinal surgery navigation system based on structured light scanning(structured light navigation system,SLNS),and to compare accuracy of pedicle screw placement using SLNS,CT based navigation system and free hand technique.Methods Thirty-two calf vertebral pedicles,40 and 32 were placed with pedicle screws using SLNS,CT navigation system,and free hand technique,respectively.The pedicle breakage ratio,transverse section angle (TSA),sagittal section angle (SSA),screw offset deviation of each screw were detected according to CT images.Results The pedicle breakage ratio of pedicle screws in SLNS group,CT navigation group and free hand group were 6%(2./32),5%(2/40),25%(8/32),respectively.The difference between each of the two navigation groups and free hand group were statistically significant regarding frequency of screw misplacement.The difference between the two navigation systems was not obvious.The average SSA error and TSA error in SLNS group were 2.58°±2.74° and 4.26°±5.20°.For CT navigation group,they were 2.95°±2.61° and 3.13°±-2.75°.There was no statistical difference between the two navigation methods for the SSA or TSA error.There was no statistical difference in offset deviation among SLNS group,CT navigation group and free hand group.Conclusion The SLNS is a new and practical navigation system,which has similar accuracy with CT navigation system.

Objective:To explore the relationship between hepatitis B virus (HBV) infection and the pathogenesis of multiple my-eloma (MM), in order to provide an epidemiological evidence for the prevention and treatment of MM. Methods:Clinical and epidemi-ological data of 185 MM patients and 182 non-tumorous patients were collected. Subjects were randomly selected from in-patients who were homeochronously admitted to the same five grade-III A hospitals, including Xi'an Central Hospital, Shaanxi People's Hospital, Xi'an Jiaotong University Xibei Hospital, and so on. MM patients were selected in terms of age and gender. Peripheral blood HBsAg was assayed by ELISA. If HBsAg was negative, the S and C-gene fragments of HBV DNA were tested using nested PCR . Fisher's ex-act test orχ2 test (SPSS statistical software) was used to compare the differences between the groups. Logistic regression was employed to examine the association between the pathogenesis of MM and HBV infection. Results:In MM patients, the HBsAg positive rate was 8.11% (15/185), the occult HBV infection (OBI) positive rate was 3.53% (6/170), and the total HBV infection rate was 11.35% (21/185). For the control group, the HBsAg positive rate was 4.40%(8/182), the OBI positive rate was 0.57%(1/174), and the total HBV in-fection rate was 4.95%(9/182). No statistical difference in HBsAg or OBI positive rate was found between the two groups (P>0.05). However, MM patients showed significantly higher total HBV infection rate than that of the controls [χ2=5.02, P<0.05;OR was 2.46 (95%CI:1.10-5.53, P<0.05)]. Additionally, the proportion of ISS stage III was significantly higher in MM patients with HBV infection than in uninfected MM patients (85.71%vs. 60.37%,χ2=5.15, P<0.05). Patients with HBV infection showed reduced albumin level (χ2=5.60, P<0.05) and aκ/λlight chain ratio (P<0.05) compared with uninfected patients. Conclusion:The risk of MM pathogenesis after HBV infection is significantly increased as OBI is included in the analyses. Furthermore, MM patients with HBV infection will develop more severe liver damage, indicating that OBI in MM patients with negative HBsAg should be screened before chemotherapy to pre-vent HBV reactivation.