Biomechanical effects of different bone cement diffusion patterns after vertebroplasty:finite element analysis / 中国骨伤

OBJECTIVE@#To investigate the biomechanical effects of different bone cement diffusion patterns in the treatment of osteoporotic vertebral compression fractures.@*METHODS@#One volunteer with L1 osteoporotic vertebral compression fracture was selected, male, aged 68 years old, heighed 172 cm, weighted 60 kg, and healthy before. CT scans were used from T@*RESULTS@#After the establishing the finite element model of osteoporotic vertebral compression fracture in the thoracolumbar segment, it was found that the deformation of three different bone cement distribution models above was not significantly different. In L@*CONCLUSION@#The bone cement contact with both upper and lower endplates can effectively absorb and transfer the stress level brought by the load, reduce the stress level of cancellous bone, and reduce the possibility of refracture of the operative vertebral body.

Surgical management of traumatic injury of upper cervical spine / 中国骨伤

<p><b>OBJECTIVE</b>To analyze retrospectively the clinical outcome of surgical management for upper cervical spine injury caused by trauma.</p><p><b>METHODS</b>From January 2005 to March 2007, 16 patients with injury of upper cervical spine were treated by different management. There were 11 males and 5 females with an average age of 44 years ranging from 24 to 75. Of all, 5 cases were the odontoid fracture, 3 were atlas fracture, 5 were Hangman's fracture, 3 were atlanto-axial dislocation. MR imaging of cervical spine showed cervical cord compression and changes of T2 high signal in 5 cases. According to the injury mechanism, the imageological appearance, fracture classification, the methods of treatment were selected.</p><p><b>RESULTS</b>Seven patients received non-operative treatment and nine patients underwent operation. Sixteen patients were followed up for 7 to 34 months (means 10.5 months). All fractures were healing or bone graft fusion and no internal fixation was lossing. There were no injuries of vertebral artery, nerve root or spinal cord.</p><p><b>CONCLUSION</b>CT and MRI are required in the course of diagnosis for the traumatic injury of upper cervical spine. The optimal modus operandi should be choose to retain upper cervical spine, meanwhile, can reserve the cervical movement.</p>

Local X-irradiation promotes regeneration of spinal cord central nervous system in a rat model / 中华外科杂志

<p><b>OBJECTIVE</b>To evaluate the effect of local X-irradiation on spinal cord injury by using physiology, kinology, electrophysiology and histology method.</p><p><b>METHODS</b>46 female Sprague-Dawley rats were subjected to spinal cord injury by weight dropping on T(11-12). All animals were divided into 3 groups randomly. One of the animal groups was irradiated with 10 Gy at the lesion site; another was irradiated with 20 Gy, the other without irradiation is regarded as sham-group. The animals were euthanized at different time points at 4 and 12 weeks after irradiation. Spinal cord callus was assessed by using physiology, kinology, and electrophysiology and histology method.</p><p><b>RESULTS</b>In all the groups, the NF at 14 weeks were found higher than that of 6 weeks. Both 10 Gy irradiated and 20 Gy irradiated groups were higher than those of group at each time point (P < 0.05). The MBP decreased at 14 weeks in irradiated groups (P < 0.05), but increased at 14 weeks in sham-group (P < 0.05), the MBP of irradiated groups was lower than that sham-group at 14 weeks (P < 0.05). The GFAP and Nogo-A at 14 weeks were higher than that in 6 weeks in all the groups (P < 0.05), and there was no statistical significance with physiology, kinology, electrophysiology test in all groups.</p><p><b>CONCLUSION</b>A self-repair mechanism exists after SCI, which will last at least 14 weeks. Local irradiation promotes the regeneration of spinal cord system after injury to some extent.</p>

Analysis of complications associated with internal fixation for lumbar spondylolisthesis / 中国骨伤

<p><b>OBJECTIVE</b>To evaluate the therapeutic effects of lumbar spondylolisthesis by decompression, instrumentation and posterolateral fusion, and study the causes of the related complications and its method for the prevention.</p><p><b>METHODS</b>One hundred and sixty-five cases with grade I to II spondylolisthesis from February 1991 to May 2007 were retrospectively analyzed. All cases were treated by posterior lumbar canal decompression, reduction with pedicle screw system and fusion with posterolateral bone grafting. Among them,there were 55 male and 110 female with an average age of 53.6 years. Besides, one segment was involved in 161 cases and two segments involved in the rest of them.</p><p><b>RESULTS</b>The complications were divided into either intraoperative postoperative complications. Intraoperative complications were 5 cases (3.0%) there were 4 cases with dura tear and 1 case with nerve root injury. Postoperative complications were 18 cases (10.9%), there were 3 cases with cerebrospinal fluid leakage, 1 case with wound infection, 2 cases with hematoma,5 cases with transient neurological deficits, 1 cases with implant failures and 6 cases with pseudarthrosis formation.</p><p><b>CONCLUSION</b>Good clinical results of lumbar spondylolisthesis can be obtained by posterior reduction and fixation with pedicle screw system. However,operation skills and strict indications play an important role in the prevention of complications.</p>

Diagnosis and operative treatment of far lateral lumbar disc herniation / 中华外科杂志

<p><b>OBJECTIVE</b>To discuss the characteristics and operative selection of far lateral lumbar disc herniation (FLLDH).</p><p><b>METHODS</b>Twenty-three cases of FLLDH, 14 were foraminal, and 9 were extraforaminal lumbar disc herniation. Of the 23 cases, low back pain was observed in 8 cases (31%), severe lower leg pain in 21 cases (91%) and Lasegue sign in 10 cases (43%). CT and MRI showed the protruded disc in and outside of the foramen clearly. Three surgical procedures were performed, including hemilaminotomy with medial facetectomy, facetectomy with pedicle screw fixation and fusion with posteolateral bone grafting, and the transmuscular approaches.</p><p><b>RESULTS</b>Twenty-two cases were followed up for an average of 3.6 years. According to the Macnab criteria, 15 patients achieved excellent results, good 4, fair 3 and poor 0. Excellent and good rate was 86%.</p><p><b>CONCLUSIONS</b>The symptoms and signs of FLLDH mainly result from injury of upper nerve segments with the dominant symptom of severe lower leg pain. CT and MRI appearance are not only sensitive but also specific for the diagnosis of FLLDH. In foraminal lumbar disc herniation, the hemilaminotomy with medial facetectomy is recommended. While in extraforaminal lumbar disc herniation, either facetectomy with pedicle screw fixation and fusion with posterolateral bone grafting or transmuscular approaches for removal of nucleus pulposus can be chosen. Microendoscopic discectomy is a new, safe and efficient method for the disease, however, a skillful microendoscopic technique should be mastered prior.</p>

The design and clinical application of a new type of dynamic Hoffmann external fixator for tibial shaft fractures / 中华创伤骨科杂志

Objective To explore biomechanical properties and clinical results of a new type of dynamic Hoffmann external fixator(NDHEF)for tibial shaft fractures.Methods Fifteen specimens of adult tibia were randomly divided into three groups and osteotomized obliquely in the mid part of the tibia.These specimens were fixed with NDHEF,improved Hoffmann external fixator(IHEF)and maltifunctional external fixator(MEF)re- spectively.The axial compression,bending,torsion and stress shielding tests were performed on the specimens in each group for biomechanical comparison.From 1995 to 2004,40 cases of open tibiofihular fractures were treated with NDHEF and 88 cases with IHEF and their clinical results were analyzed and compared.Results The biomechanical tests showed that the compressive rigidity,bending rigidity and torsion rigidity of NDHEF were similar to those of IHEF(P＞0.05)but significantly stronger than those of MEF(P＜0.05).The stress shielding of NDHEF was obviously weaker than that of other external fixators(P＜0.05).All the 128 cases were followed up for 12 to 36 months(average,16.8 months).The mean substantial bone healing time for NDHEF treatment was 22.3 weeks and that for IHEF was 26.8 weeks.The difference was significant(P＜0.05).The rates of delayed union and malunion were all 7.5% for NDHEF,but 15.9% and 4.5% respectively for IHEF.The difference was insignificant (P＞0.05).Conclusions The biomechanical performance of NDHEF is superior to that of IHEF,for it can diminish the stress shielding and accelerate bone healing.It is a good external fixator for tibial fractures.