Objective To explore the feasibility and application value of combined C2 laminar screw fixation technique in treatment of cervical vertebral injury. Methods Dense axial CT scanning was done on C2 laminar of 32 specimens of cervical vertebra to measure the length and height of the axis, the thickness of upper, middle and lower parts of the axis as well as the angle between the axial ray and the sagittal plane. There were eight patients with cervical vertebral injury including two with type Ⅱ odon-told process fractures combined with backward dislocation of atlanto-axial joint, one with forward disloca-tion of atlanto-axial joint, one with nonunion of odontoid process fractures, two with type Ⅲ odontoid process fractures combined with atlanto-axial joint instability and transverse ligament rupture, one with type Ⅱ Hangman fracture combined with instability of C2～3 and one with forward dislocation of atlanto-axial joint combined with transverse ligament rupture. With accomplishment of traction reduction, combined fixation with axis laminar screws and posterior autogenous lilac graft fusion were done based on injury se-verity of the patients. Results The length and height of axis laminar was (26.2±1.2) mm and (12.8±1.6) mm, respectively. The thickness of upper, middle and lower parts of the C2 laminar was (3.0±1.4) mm, (6.0±1.6) mm and (5.6±1.2) mm, respectively. The mean angle between the axial ray and sagittal plane was 43.5°. All patients were followed up for 6-14 months ( mean 6 months), which showed that all patients obtained favourable bone union and all screws remained at sound position, without deflexion of the screws or any perioperative or postoperative complications. No screw loosening or breakage occurred. Conclusions C2 laminar screw fixation technique can prevent the risk of vertebral artery injury during screw insertion. In the meantime, such technique is simple to operate and free from limitation of the vertebral artery in the cervical foramen. Whole course of visualization during C2 laminar screw insertion may facilitate it as a supplementary method for conventional posterior C2 screw fixation.

Objective To investigate the effects of zoledronic acid on the expression of HIF-1α and VEGF in osteosarcoma LM8 cell line under hypoxic condition. Methods The hypoxic culture model was established. After LM8 cells were treated with zoledronic acid, semi-quantitative PCR was used to assess the expression of HIF-1α and VEGF mRNA. The expression of HIF-lct and VEGF protein was de-tected by immunohistochemical staining and ELISA respectively. Results Compared with cells in normoxic conditions, cells in the hypoxic environment and cells treated with zoledronic acid in the hypoxic condition did not show a significant change in the mRNA level of HIF-1α(P >0. 05). However, the protein expression of HIF-1α was markedly decreased in the cells treated with zoledronic acid in the hypoxic envi-ronment. In contrast, both mRNA and protein expression levels of VEGF were down-regulated in the zoledronic acid treatment hypoxic group (P <0.05). Conclusion Under hypoxic conditions in vitro, zoledronic acid inhibited the expression of HIF-1α protein, which decreased VEGF mRNA level and protein expression in osteosarcorna LM8 cell line.

Objective To analyze the feasibility and effect of combining intramedullary nails and plates in the treatment of ipsilateral unicondylar tibial plateau fractures with non.contiguous tibial shaft fractures.Methods From May 2003 to November 2005,21 patients with ipsilateral unicondylar tibial plateau fracture and non-contiguous tibial shaft fracture were treated with combining intramedullary nails and plates,including 15 males and 6 females,with the mean age of 34 years (range,20-55 years).The tibial plateau fractures were classified according to Schatzker et al.; 4 cases were type Ⅰ,11 cases type Ⅱ,6 cases type Ⅲ and 1 case type Ⅵ.Middle third tibial shaft fractures were in 13 patients,and distal third tibial shaft fractures were in 8 patients.Once the reduction was obtained,we first fixed tibial plateau with plate and then tibial shaft with medullary nail in 19 cases; in 2 cases,we first fixed the tibial shaft with medullary nail and then tibial plateau with plate.Results 1All patients were followed up for 0.9 to 4 years (average,2.2 years).Bone union was obtained in all patients.The tibial plateau fractures united after an average of 12 weeks,and the tibial shaft fractures united after an average of 29 weeks.Delayed union of the tibial shaft fracture occurred in 3 patients,and the fracture healed finally by removing the proximal locking.Tibial plateau malunion occurred in one patient due to malreduction.According to HSS scores,excellent result was obtained in 17 patients (80.95％),good in 3 patients (14.29％),fair in 1 patient (4.76％).Conclusion With careful attention to some techniques,ipsilateral unicondylar tibial plateau fractures with non-contiguous tibial shaft fractures can be treated successfully by combining medullary nail and plate.

Objective To compare anatomically the potential incidences of injury to the nerve roots of ventral and dorsal rami caused by the transarticular screws and Magerl lateral mass screws in the fixation of subaxial cervical spine.Methods Fixations with the transarticular screws and Magerl lateral mass screws were performed in this study.For each kind of fixation,20 screws were inserted from C3 to C7 in two specimens.A 20-ram long screw was used to over-penetrate the ventral cortex.The anterolateral aspect of the cervical spine was carefully dissected to allow ob- servation of the screw-ramus relationship.Results The overall percentage of nerve violation was significantly lower in the transarticular screw fixation(45%)than in the Magerl lateral mass screw fixation(90%).The difference was sta- tistically significant between the two fixation methods(P＜0.05).The greatest percentages of nerve violation caused by the transarticular screws and lateral mass screws were found at the dorsal ramus,25% and 45%,respectively. Conclusion The potential risk of nerve root violation caused by the transarticular screw technique is lower than that by the Magerl lateral mass screw technique in the lower cervical spine.

Objective To discuss the strategies for treatment of lower cervical distractive flexion injuries. Methods Sixty-eight patients including 43 males and 25 females at age range of 18-72 years (average 43 years) suffered from lower cervical distractive flexion injuries were operated from January 2002 to June 2007. According to Allen's classification, there were 7 patients at grade Ⅰ, 19 at grade Ⅱ,29 at grade Ⅲ and 13 at grade Ⅳ. Temporary skull traction was used for each subject before surgery. Only posterior approach was performed in 26 patients who were fixated by pedicle screw system,lateral mass screw system or transarticular screw system. Combined anterior and posterior approach was applied for the other 42 patients at one stage. The curative effect was followed up for all patients after the procedures. Results All patients were followed up for 6-65 months ( average 34 months), which showed posterior incision infection in 2 patients who were cured after debridement or change dressing. Two patients with aggravated neural symptome were cured following treatment with methylprednisolone. Neural function was improved at least for one level in all patients except for 18 patients (Frankel A). Of 11 patients at grade B, there were 4 patients improved to grade C and 5 to grade D. Of 10 patients at grade C, there were 6 patients recovered to grade D and 4 to grade E. All 15 patients at grade D reached grade E. It was not found loosening, breakage or defuxion. The graft bone was fused within 3-4 months, with no any complications related to surgical fixation. Conclusions The strategies for lower cervical distractive flexion injuries should be taken according to Allen' s classification. Single posterior procedure is suitable for grade Ⅰ and Ⅱ injuries. While combined posterior and anterior procedure can be used for grade Ⅲ and Ⅳ injuries.