Objective To compare the influence of the dynamic device(DD) of pedicle screw fixation and its equivalent rigid device (RD) on bone mineral density and bone structure of the vertebrae. Methods 24 goats were randomly divided into 4 groups: control group, single posterolateral fusion group, dynamic device with posterolateral fusion group and rigid device with posterolateral fusion group. After 24 weeks postoperative observation, the animals were sacrificed and the fixed lumbar spines were harvested. The bone mineral density (BMD) of these harvested specimens was measured by quantitative computed tomography (QCT). Then the L3 segment was embedded in methyl methacrylate and sectioned after alcoholic dehydration. Undecalcified slides (50 ?m in thickness) were stained with toluidine blue. Quantitative histologic analysis was performed in a semiautomatic way. The static parameters consisted of trabecular bone volume (TBV), the mean trabecular plate thickness (MTPT) and mean trabecular spacing (Tb.Sp). The main dynamic histomorphometric parameter, bone mineralization rate (MAR), was calculated by measuring the mean distance between two flurochrome labelings. Results The BMD in the rigid device group decreased significantly compared with control group (P

[Objective]To investigate the influence of pressure on the proliferation of rabbit bone marrow stromal cells(MSCs) and explain the relationship of the hip prosthesis submerge and loosening with continuous pressure after revision of total hip replacement.[Method]A unit of MSCs pressure model was set up to load different pressures on MSCs cultured in vitro.[Result]MSCs showed more proliferation capacity under discontinuous pressure.MTT assay was used to determine the cell proliferation of primarily cultured MSCs under discontinuous pressure.The MSCs OD value of pressured groups was much smaller than the control group at different times.Various magnitudes and durations of the discontinuous pressure could significantly suppress MSCs proliferation with the magnitude-dependent.[Conclusion]At the early period after revision of total hip replacement,patients should lie and exercise on the bed until 6 weeks.Otherwise,the weight-bearing pressure may restrain MSCs proliferation which is harmful to union and may cause prosthesis submerge and loose.

ObjectiveTo analyze the stress contribution of different cement volume to the adjacent vertebral endplates in percutaneous kyphoplasty (PKP) so as to explore the possible mechanism of adjacent vertebral fractures after PKP.Methods The three-dimensional finite element model of osteoporotic thoracolumbar vertebral compression fractures was established to simulate vertebral body partial restoration (80％) with PKP.During the process,two doses of bone cement ( polymethylmethacrylate,PMMA) were filled in the vertebral body (4.0 ml bone cement filling 15％ of the vertebral body volume and 8.0 ml bone cement filling 30％ of the vertebral body volume).Endplate stress under conditions of axial compression,flexion and extension was analyzed. ResultsRegarding the two filling doses in PKP,the adjacent vertebral endplate stress under the above-mentioned conditions was all increased at T11 and L1 vertebral body compared with that before operation.Meanwhile,endplate stress had positive correlation with the cement volume and the stress concentrated largely in the anterior and middle parts of endplate.ConclusionsThe stress of adjacent vertebral endplate is positively correlated with cement volume,with anterior and middle parts of endplate as the stress concentration.The probability of adjacent vertebral fractures shows a rising trend with the increase of cement volume in PKP.

Objective To evaluate the mid-term clinical effects and the imaging changes of Coflex interspinous dynamic internal fixation for low back pain. Methods From February 2007 to June 2009,Coflex interspinous dynamic internal fixation was performed in a consecutive 45 patients. They included 26 males and 19 females, with an average of 51.4 years ranging in age from 45 to 70 years. Thirty-two cases were in L4.5 level, 11 in L5S1 level and 2 in both two levels. The patients were treated with limited laminectomy and implanted with Coflex device. Clinical outcomes were assessed by Oswestry disability index (ODI)scores and Japanese Orthopaedic Association (JOA) questionnaires before and after operation. The imaging examination was obtained to assess height of the intervertebral space, area of the intervertebral foramen,segment movement of the operation level, low lumbar curvature and signal of the lumbar disc on MRI. Results The follow-up time ranged from 10 to 34 months, with an average of 24 months. The ODI scores decreased significantly from 62.82±10.42 preoperatively to 11.80±3.35 postoperatively. The JOA scores were improved remarkably from 9.00±2.63 preoperatively to 24.65±1.86 postoperatively. The proportion with optimal effect was 89% (40 cases). The Cobb angle after operation of L4.5 and L5S1 level was 15.1°±3.9° and 16.3°±3.8° respectively, which was significantly decreased after operation. The range of motion of the L4.5 level increased from 6.5°±1.5° to 8.4°±2.6° while the L5S1 level did not change notedly. The heights of the dorsal intervertebral disc, distance of the spinous processes, intervertebral foramen height and area were significantly higher than those before operation. Conclusion The Coflex interspinous dynamic internal fixation is available to reserve segment movement, to increase intervertebral space height and foramen area. Meanwhile,it is effective to self-repair and prevent degeneration for the disc in adjacent levels.

Objective To develop a three-dimensional finite element model of atlantoaxial instability and compare the biomechanical properties of percutaneous anterior transarticular screw (ATS) and posterior transarticular screw (PTS) fixations.Methods A pathologic three-dimensional finite element model of atlantoaxial instability was developed from CT images of the upper cervical spine of volunteers with the aid of softwares,such as Mimics,Freeform,and Ansys.Percutaneous C1-2 ATS and PTS fixation modes were simulated and implanted to the model.Under the preload of 40 N and force moment of 1.5 Nm in anterior flexion,posterior extension,lateral bending,and axial rotation,biomechanical properties of the two fixation modes were compared.Results Under the four loading modalities,both fixation techniques provided maximal inhibition on C1-2 movement.The maximal stress for ATS was larger than that for PTS and maximal displacement for ATS was smaller than that for PTS.Conclusions Both ATS and PTS provide similar outlook and are effective to stabilize the atlantoaxial joint.Biomechanical performance of percutaneous C1-2 ATS is better than that of percutaneous C1-2 PTS.

Objective To analyze the incidence and risk factors of contralateral radiculopathy in patients after unilateral transforaminal lumbar interbody fusion (TLIF) surgery.Methods A retrospective study was conducted within 587 patients (average age 57.1 years,range 19-71 years) who underwent unilateral TILF from January 2010 to January 2014 in our hospital,including 334 males and 253 females.Patients were divided into a symptomatic group and an asymptomatic group.The causes of contralateral neurological symptom were evaluated according to the radiological data.The difference of pre-and post-operative contralateral foramen area (CFA),segmental angle (SA) and the clinical treatment outcomes (VAS,JOA score) were compared between two groups.Results Patients were followed up for 9-21 months,average 15.1 months.Post-operative contralateral radiculopathy occurred in 28 (4.8％) of the patients who underwent unilateral TLIF,including contralateral foraminal stenosis in 16 (57.1％,16/28),screw malposition in 5 (17.9％,5/28),contralateral lateral recess stenosis and/or newly developed disc herniation in 3 (10.7％,3/28),hematoma in 1 (3.6％,1/28),cement compression in 1 (3.6％,1/28),and unknown origin in 2 patients (7.1％,2/28).Nineteen (3.2％,19/587) of the 28 patients received revision surgery because of ineffective conservative treatment.Compared with the asymptomatic group,the difference of pre-and post-operative CFA was significantly smaller (-13.8±13.2 mm2) in symptomatic group,while the SA was significantly greater (7.0°±9.8°) in symptomatic group.The JOA score at 3 months after the surgery was significantly improved in asymptomatic group (63.0％±18.1％,P＜0.05).Conclusion The incidence rate of contralateral neurological symptom was 4.8％ in the present study.The potential risk factors associated with contralateral radiculopathy were predominantly contralateral foraminal stenosis and screw malposition.The excessive restoration of SA might have an effect on contralateral nerve compression,which should arouse the attention of the surgeon.

AIM:Toinvestigatewhetherautophagyisup-regulatedwhenresveratrol(Res)inducesapoptosis in chondrosarcoma , and to study the effects of autophagy inhibitor combined with Res on chondrosarcoma .METHODS:SW1353 cells were divided into 4 groups: control group, Res group, 3-methyladenine (3MA) group, and Res +3MA group.Electron microscopy was used to observe the autophagyosomes in control group and Res group .At the same time, the viability of the cells in the 4 groups was detected by CCK-8 assay.TUNEL staining and Western blotting (for determi-ning the levels of cleaved caspase-3, Bax and Bcl-2) were used to reflect levels of apoptosis in all groups .The expression of autophagy-related proteins Beclin 1, LC3-Ⅱ and p62 was detected by Western blotting .RESULTS: Exposure of the cells to Res resulted in a decrease in cell viability and an increase in the level of apoptosis ( P<0.05 ) .Compared with control group, the level of apoptosis was increased but the autophagy was decreased (P <0.05).Compared with Res group, the cell viability and the level of autophagy were decreased and the level of apoptosis was increased ( P<0.05 ) . CONCLUSION:Resveratrol induces apoptosis and autophagy , and inhibition of autophgay enhances resveratrol-induced apoptosis in chondrosarcoma .

Objective To compare the clinical efficacy and radiologic changes between constrained and non-constrained titanium plate in anterior cervical corpectomy and fusion (ACCF) in elderly cervical spondylosis patients.Methods A total of 58 elderly cervical spondylosis patients who underwent ACCF were divided into group 1 (patients treated with constrained titanium plates,n =30) and group 2 (patients treated with non-constrained titanium plates,n=28).The Japanese Orthopedic Association (JOA) score,fusion rate,the loss of segmental height and cervical lordosis were recorded.The clinical efficacy and imaging features were compared between the two groups.Results The improvement rate of JOA score had no significant differences between group 1 and group 2 [(77.7±18.6)％ vs.(75.8±23.2)％,t=0.340,P＞0.05].At 3 months after operation,the fusion rate was higher in group 2 than in group 1 (89.3％ vs.63.3％,x2 =5.327,P＜0.05).At 3,6 and 12 months after operation,there were no significant differences in the loss of segmental cervical height and lordosis between group 1 and group 2 [(2.42±3.05)mm vs.(0.98±2.86)mm,(3.95±3.65)mm vs.(2.34±2.97)mm,(3.60±4.33)mm vs.(2.40±2.96)mm,(1.64±2.33)° vs.(0.66 ± ±2.14)°,(2.13∧±±3.79)° vs.(0.70±2.99)°,(2.39±4.26)° vs.(0.86±3.25)°,respectively,all P ＞0.05].Conclusions The clinical efficacy is similar in ACCF with the two types of titanium plates.The non-constrained titanium plate can increase the fusion rate in early time,but may aggravate the loss of segmental cervical height and lordosis,which should be used with caution in elderly osteoporosis patients.

Objective To evaluate the effect of different preparation processes on preparation of the glial cell line-derived neurotrophic factor(GDNF)loaded microspheres and observe the biological activity of GDNF.Methods With polylactide-co-glycolide(PLGA)as the coating material,the GDNF-loaded microspheres were prepared by using double emulsion(W1/O/W2).Two-factor factorial design variance analysis was done to analyze the effects of the composition proportion of lactic acid(LA)and glycolic acid(GA)in PLGA and the stirring speed of multiple emulsion on particle size,entrapment efficiency,burst release and in vitro release characteristics of the GDNF-loaded microspheres.PC-12 bioassay was employed to detect the biological activity of the released GDNF so as to determine the optimal preparation process.Results The composition proportion of PLGA could affect the microspheres'burst release(P ＜ 0.05),with no effect on particle size and entrapment efficiency.with the higher.With higher proportion of GA,the release speed of GDNF in the microspheres was increased.When the stirring speed of multiple emulsion was increased from 1 000 r/min to 3 000 r/min,the particle size of the microspheres was decrease significantly(P ＜ 0.01),the burst release was increased markedly(P ＜ 0.01)and the in vitro release rate was accelerated.The activity of GDNF in the microspheres could last for about 20 days at 37℃,which was 10 days longer than that of single GDNF.Conclusions Double emulsioncan prepare the GDNF-loaded microspheres with high entrapment efficiency and suitable in vitro release time.In the meantime,the microspheres can extend the validity of GDNF.

Objective To study the feasibility and clinical effect of percutaneous C2 pedicle lag screw in treatment of Hangman's fracture and define the indications of the technique. Methods There were 9 patients including 5 males and 4 females at average age of 36 years (26-68 years). According to a Levine and Edwards System, there were 5 patients with type Ⅰ hangman' s fracture, 3 with type Ⅱ hangman' s fracture and 1 with type Ⅱ A hangman' s fracture. According to American spinal injury association (ASIA) system, the spinal cord function was ranked at Type D in 2 patients and Type E in 7. All patients achieved anatomic reduction by skull traction. Under general anesthesia, 9 patients were fixed with percutaneons C2 pedicle lag screw. The whole procedure was done under monitoring of "C"-arm fluoroscopy for safety and accuracy. Results All patients obtained bony fusion within 2-3 months, with no infection, neurological deficits, vertebra artery injury or other complications. CondusionsThe percutaneous C2 pedicle lag screw fixation is minimally invasive and effective for treatment of Hangman's fracture. During the course of treatment, the function of upper cervical spine remains unaffected.