[Objective]To observe the clinical results of a hollow compression nail applied to treat the separation of elements of neural arch.[Method]Since February,2003,sixteen cases of separation of elements of neural arch have been treated with a hollow compression nail and bone grafting .The mean age of the group was 32,from 18 to 54.Five cases of separation of elements of neural arch located at L4 and the other 11 at L5.All the patients suffered from severe back pain.During the operation,the presence of the pars interarticularis defect was confirmed.The defects were cleared of any fibrous and cartilaginous tissues.The sclerotic bone margins were curetted until bleeding was noted .Autograft harvested from posterior ilium was done.The hollow compression nail was placed onto the index vertebra.[Result]All the patients were followed-up for more than 14 months (14～26 months).The significant back pain relief was found in all the cases.The bony healing was comfirmed in 11 cases,and the other 5 were in the process of bone growth.[Conclusion]The separation of elements of neural arch can be treated by the hollow compression nail without spinal fusion.The hollow compression nail is proved to be safe and effective.

[Objective]To explore the feasibility and outcome of posterior single open-door and pedicle screw in treating canal stenosis and instability of cervical vertebrae at one time.[Method]The preoperative radiographs of 15 patients were measured and were diagnosed to be developmental spinal canal stenosis and instability of cervical vertebrae.MRI showed the spinal cords were compressed obviously.Posterior C_(3~7) single open-door decompression and canal-plasty was adopted.Self-designed pedicle screws and intertransverse fusion were used in the unstable segments.[Result]Complications were not found after the operation.The postoperative radiographs showed that the screws were in the right places.The average follow-up time was 13 months,ranging from 7 to 18 months.The short-term radiographs showed firmly fixed screws.[Conclusion]It is a simple and reliable method to treat canal stenosis and instability of cervical vertebrae at one time with posterior single open-door and pedicle screw.Anterior and posterior operations have been avoided and the short-term outcome is satisfied.

OBJECTIVE To explore the sterilizing effect of low-temperature vacuum formaldehyde.METHODS The test group used the own-produced 140 L low-temperature vacuum formaldehyde sterilizer for sterilization;and the control group used "Xinhua" hydrogen peroxide plasma sterilizer.Sterilization effect of the two groups was monitored by biological indicator.RESULTS After 50 sterilization procedures run in test group,the biological indicators the bacterial were all killed,the qualification rate of sterilization was 100%.But after 30 sterilization procedures run in control group,only 8 procedures were qualified,the qualification rate of sterilization was 26%.The sterilizing effect of the two groups was significantly different(P