Objective To explore the biomechanical stabil ity of dynamic sleeve three-wing screw for treatment of femoral neck fracture and to provide theoretical basis for choosing dynamic sleeve three-wing screw in cl inical appl ication. Methods Nine human cadaveric femurs were selected and divided randomly into 3 groups (n=3), excluding deformities, fractures, and other lesions. The central neck of the specimens were sawn with hand saw respectively at Pauwels angles of 30, 50, and 70°. All cut ends were fixed with dynamic sleeve three-wing screw. Instron-8874 servohydraul ic mechanical testing machine was used to fixed the specimens which simulated uni ped standing, at the rate of 10 mm/minute and l inear load 0-1 200 N at 11 key points. The strain values of princi pal pressure side and princi pal tension side under different loads were measured. Results There was a peak at 6th point in the 1 200 N load. The strain values at Pauwels angles of 30, 50, and 70° were (—1 657 ± 171), (—1 879 ± 146), and (—2 147 ± 136) με; showing significant differences (P lt; 0.01). The strain values of princi pal pressure side and princi pal tension side of the femoral neck became higher with the increasing Pauwels angle under the same load, showing significant differences (P lt; 0.01). The strain values became higher with the increasing load under the same Pauwels angle (P lt; 0.01). Conclusion Dynamic sleeve three-wing screw has good biomechanical stabil ity for treatment of femoral neck fracture. It explains theoretically that the fracture is more unstable with the increasing Pauwels angle．
Objective To investigate the effects of montelukast ( MK) on the airway inflammation and the risk of the recurrence of wheezing in the treatment of infants with RSV bronchiolitis.Methods 60 infants ( aged 6-24 months) with RSV bronchiolitis admitted between December 2010 and December 2011 were recruited in the study. They were randomly assigned into a conventional group and a MK group ( n =30 in each group) . All patients received conventional treatments including inhalation of budsonide and so on.The subjects in the MK group received oral montelukast ( 4 mg qn for 12 weeks) additionally. The levels of serum cysteinyl leukotrienes ( CysLTs ) , total immunoglobuline E ( T-IgE) , eosinophil cationic protein ( ECP) and fractional exhaled nitric oxide ( FeNO) were assayed before and after the treatments. Thenumber of recurrence of wheezing was recorded through outpatient and telephone follow-up for 12 months. 30 healthy infants participating the health examination in outpatient were selected as control, and those who got atopic disease or respiratory tract infections recently were excluded. Results The levels of CysLTs, ECP and FeNO of the patients with RSV bronchiolitis before treatment were significantly higher than those in the normal control group, and the levels of CysLTs and FeNO were significantly decreased after treatment ( P lt;0. 05) . The levels of CysLTs and FeNO after treatment in the MK group was significantly lower than those in the conventional group. The level of ECP was significantly decreased after treatment in the MK group ( P lt;0. 05) ,·186· Chin J Respir Crit Care Med, March 2013 , Vol. 12 , No. 2 http: / /www. cjrccm. com which was not significantly changed in the conventional group( P gt; 0. 05) . The number of recurrence of wheezing in the MK group was more less that that in the conventional group ( P lt; 0. 05) . Conclusion Maintenance treatment with montelukast after the treatment of the acute phase of bronchiolitis can prevent recurrence of wheezing by suppressing airway inflammation in infants with RSV bronchiolitis.
Objective To investigate the cl inical appl icabil ity and value of internal fixator for the reconstruction of lumbar isthmus in the treatment of lumbar vertebral spondylolysis and to lay a fundation for its cl inical appl ication. Methods Sixteen healthy goats weighing 22.65-31.22 kg were selected to establ ish the models of vertebral spondylolysis at L5, which thereafter were randomized into two groups (n=8): bone graft group in which 0.8-1.1 g fresh autogenous bone was transplanted into the isthmus spondylolysis area, and internal fixation with bone graft group in which internal fixator was installed before transplanting 0.8-1.1 g fresh autogenous bone into the isthmus spondylolysis area. All animals were killed 8 weeks after operation to receive imaging, topographic anatomy and histology detection. Meanwhile, biomechanics test was performed by using 5 donated vertebral body specimens (4 males and 1 female aged 35-51 years old). The left isthmus of L5 vertebra was transected to serve as lumbar vertebral spondylolysis model. A mini-displacement sensor was put at the transected ends of the isthmus. Then loading was conducted with a constant velocity of 2 mm/min by electronic omnipotent tester simulating the direction of fixation force of the internal fixator, and the deformation value of the transected ends was collected by a dynamic data collector and analyzer. The loading wascontinued until the vertebra specimens were damaged. The deformation of displacement sensor and the closure of transected ends of the lumbar isthmus were observed. Results All the goats behaved normally shortly after operation, and no nerve injury induced by operation and no wound infection occurred. Bilaterally obl ique X-ray films of lumbar vertebra and topographic anatomy 8 weeks after operation showed the fusion rate of the internal fixation and bone graft group and the bone graft group was 100% and 62.5%, respectively, indicating there was a significant difference (P lt; 0.05). Histology observation showed 3 goats in the bone graft group presented empty bone trabecula, empty bone lacuna and the disappearance of osteocytes at the transected ends of lumbar isthmus; while in the internal fixation and bone graft group, the bone trabecula grew into cancellous structures with hematopoietic and fatty bone marrow tissue inside, and parts of the bone trabecula had various degrees of mosaic-l ike pattern. During the upload, the biomechanics test and data processing results showed when the external load was 40 N, the deformation of displacement sensor was identified and the gap between the transected ends of lumbar isthmus started to close; then with the increase of external load, the displacement sensor tended to ascend in a l inearity manner; while when the external load was 212 N, the displacement sensor had no further deformation, the gap between the transected ends of lumbar isthmus wascompletely closed, and the pressor effect appeared. Conclusion The internal fixator for the reconstruction of lumbar isthmus has mechanical effects of stabil izing and elevating pressure with a high fusion rate.