Objective To investigate the clinical effect of posterior short-segment pedicle screw reduction and fixation without fusion in treatment of thoracolumbar mono-segmental compression fractures.Methods Thirty cases of thoracolumbar mono-segmental compression fractures admitted from January 2009 to February 2010 were assigned to single posterior pedicle screw fixation (screw group,n =15) and posterior pedicle screw fixation with posterolateral fusion (fusion group,n =15) according to random number table.Clinical results in the two groups were assessed based on Cobb' s angle,anterior vertebral body height ratio (％) and Oswestry disability index (ODI) before operation,after operation,prior to the removal of implant and at the latest follow-up.Results All the cases were followed up for average 24 months.Both operation time and blood loss were less in screw group than in fusion group [(76.58 ±12.67) min vs (116.29 ± 17.45) min,P ＜ 0.01 ; (287.54 ± 30.76) ml vs (480.34 ± 100.54) ml,P ＜0.01],whereas there were no statistical differences between the two groups in aspects of Cobb' s angle and anterior vertebral body height ratio before and after operation,prior to the removal of implant as well as at the latest follow-up.Moreover,no statistical difference of ODI was noted between the two groups prior to the removal of implant and at the latest follow-up.Conclusion Posterior pedicle screw fixation without bone grafting achieves similar effects with pedicle screw fixation with bone grafting.

Objective:To explore the role of matrix metalloproteinase 12 (MMP12) in airway macrophages and pulmonary neu-rogenic substance P ( SP ) in the pathogenesis of asthma by analyzing their relationship in different categories of asthmatic patients.Methods:Twenty patients of asthma remission phase ( remission asthma group ) , twenty ones of mild acute exacerbation asthma (mild asthma group) and twenty healthy adults (normal control group) were included,respectively.After lung function was measured,the numbers of macrophage in induced sputum were counted.The expression levels of MMP12 mRNA and protein in sputum macrophages were detected by quantitative reverse transcription polymerase chain reaction and Western blot.The concentration of sputum SP was assayed by enzyme immunometric assay.Results: ( 1 ) Compared with the subjects in normal control group, forced expiratory volume in 1 second%predicted ( FEV1 ) and forced expiratory flow rates at 50% of the forced vital capacity % predicted ( FEF50 ) were much lower and the numbers of sputum macrophages were much higher in the patients in different asthmatic groups.Compared with the patients in remission asthma group,FEV1 and FEF50 were much lower in the ones in mild asthma group.(2) MMP12 expressions in the macrophages and the concentrations of SP in sputum were significantly increased in the patients in different asthmatic groups compared with those in normal control group;Furthermore,MMP12 and SP in mild asthma group were much higher than in remission asthma.(3) In all patients from different asthmatic groups,mRNA expressions of MMP12 in the macrophages were positively correlated with the levels of sputum SP or the numbers of sputum macrophages,whereas negative correlations between mRNA expressions of MMP 12 and FEV 1 or FEF50 were observed.Conclusion: The regulatory imbalance of macrophages′MMP12 and pulmonary neurogic SP may participate in the pathogenesis of asthma and become the potential targets for asthma therapy.