Objective To evaluate the safety and efficacy of one-level posterior lumbar interbody fusion(PLIF) combined with Prospace and facet fusion using local autograft. Methods Clinical and radiographic data of 76 patients treated by this technique was reviewed from May 2002 to December 2004. Of them, there were 52 males and 24 females, with an average age of 53.2 years (23-81 years), including 60 cases of degenerative disc disease, 9 cases of failed back surgery syndrome and 3 cases of spondylolysis. The disese courses were 1.2-8.7 years (mean 3.6 years). The levels of PLIF were: L2,3 in 2 cases, L3,4 in 7, L4,5 in 54, L5/S1 in 10, L4/S1 in 1 and L5,6 in 2. After decompression, Prospace was inserted into interbody space bilaterally,and located in disc space 4 mm beyond the rear edge of the vertebral body. Local laminectomy autograft was packed both laterally into and between 2 implants. Then the remanent local autograft was placed over facet bed. Pedicle screws were used after insertion of Prospace. Clinical results were evaluated by the JOA score. Disc height ratio and lumbar lordosis angles were measured on lateral radiographs. Fusion status was determined by evidence of bridge trabeculae across facet joint and interbody space on CT scan without mobility in lateral dynamic X-rays, and no radiolucent gap between Prospace and endplate. Paired t-test was used for statistical analysis. Results Mean blood loss and operative time was 384 ml and 178 minutes, respectively. The average JOA score at final follow-up (26.1 + 2.7) was significantly improved when compared with that of pre-operation (14.5 ± 4.0, P ＜ 0.05), with a mean recovery rate of JOA score 81.1% (37.5%-100.0%). The fusion rate was 97.4% (74/76). Mean disc height ratio and the involved segmental lordosis angle were increased from preoperative 0.27 ±0.07 and 5.8 + 2.2° to 0.33 + 0.06 and 11.3 + 2.0° respeetively at the final follow-up, and the differences were significant ( P ＜ 0.05). There were no device-related complications. Conclusion This surgical technique combined with Prospace interbody device is a safe and effective surgical option for patients with one-level lumbar disorders when PLIF is warranted.

Objective To investigate the changes of somatosensory-evoked potential(SEP)during an mild impact spinal cord injury in rats 80 as to evaluate its potential value in prevention of such iatrogenic damage. Methods Twenty-four SD rats weighing(340±28)g were randomly divided into two groups,ie,sham control group(only exposure without impact at C6)and injury group(mild impact spihal cord injury at C6).SEP wss recorded in both groups.The changes of SEP in waveform,amplitude and latency were observed and compared between groups and between operations.The gross dissection and histologic analysis were performed after surgery for comparative study. Results SEP waveforms,amplitude and latency showed no significant change in the sham control group.In contrast,the SEP waveform and amplitude animals showed significant changes in the injury group after impact spinal cord injury and the amplitude was decreased from pre-injury(1.3±0.7)μV to post-injury(0.5±0.4)μV(P<0.05),while the latency showed no significant difference between(11.1±2.1)ms pre-injury and(10.7±1.3)ms post-injury(P>0.05).However,this abnormal change appeared in a temporary period at(5.7±3.2)minutes after impact and lasted for about(7.1±3.3)minutes.Diffused hemorrhagic nidus could be seen in the injured cord,which was not found in the sham control group. Condusions Mild impact spinal cord injury may induce transient abnormalities of SEP in waveform and amplitude,which requires careful monitoring in clinical practice.The sudden change in SEP may be associated with impact and vibration damage to the spinal cord,suggesting timely use of protection measures for spinal cord.

Objective To establish a novel chronic compressive cervical spinal cord injury rat model,to validate the chronic pathological characteristic.Methods Fifty-four SD rats were randomly divided into 3 groups,including control group(n =6),acute compressive group(4 h,24 h,respectively.n =6),and chronic compressive group(4 h,12 h,24 h,48 h,72 h and 1week,respectively.n =6).Two sizes of water-absorbing polyurethane polymer sheets were implanted into C5～6 epidural space on postero-lateral side in acute and chronic compressive group respectively,to induce a consistent compression in the cord after expanded.While a laminectomy on C5～6 was performed only in control group.The neurological integrity,MRI signal change in the cords,large motoneuron number in the ventral horn,and myelin staining intensity on posterior funiculus were studied.Results In the acute group at 4-24 h,the compression was confirmed significantly on T2WI image,as well as hypointense signal change intramedullary.These changes were consisted with intramedullary bleeding,tissue necrosis.Large motoneuron number(P ＜ 0.05),rather than myelin staining intensity (P ＞ 0.05),was significantly decreased compared with the control group and chronic compressive group.BBB score was 6.0 at 24 h.In the chronic group:cord distortion with progressive compression was observed on T2WI image,but without intramedullary bleeding signal change.At 4-12 h,intramedullary edema,central canal distortion were seen in the cords.Large motoneuron number and myelin staining intensity decrement were not significant(P ＞0.05).BBB score was 20.6.At 24-72 h,central canal enlargement,venous congestion,and edema were observed.Large motoneuron number was less than that in the control group.In the compressive epicenter,nerve fiber disorganization or rupture was observed.Myelin staining intensity decreased significantly after 48 h and 72 h compression (P ＜0.05).BBB score was 19.3.At lweek,vacuolation changes were noted and large motoneuron decreased (P ＜ O.05),as well as myelin density and staining intensity (P ＜ 0.05),suggesting nerve fiber demyelination.BBB score was 17.5.In the control group,there was no neurological deficit and pathological change in the cords.Conclusion The pathology and MRI characteristic consistent with chronic compressive injury change,which proved this method is able to induce a chronic course on the rat model,and established a reliable model foundation for cervical myelopathy.

ObjectiveThe aim in this study was to evaluate the efficacy of the ball tip probe technique in placing pedicle screws in patients.MethodsFrom May 2009 to June 2010,we used ball tip probe technique in pedicle screw placement in patients with scoliosis,spondylolisthesis,spinal fractures and other diseases.The ball tip probe consisted of a metal shaft with a metal ball-shaped tip whose size included 1.5,2.5,3.0,3.5 mm in diameter.The ball tip probe with a diameter of 1.5mm owned a high rigidity and certain flexibility.Ball tip probe technique:A high speed bur was used to remove cortical bone and create a starting point,and then the ball tip probes is tapped gently by a hammer for making a guide hole through the pedicle into the vertebral body.The accuracy of the pedicle screw placements was evaluated on postoperative axial CT scanning The pedicle screw placements was compared between the the ball tip probe group and conventional freehand technique group.ResultsThree hundred and twelve screws were evaluated in the ball tip group and 276 in the conventional freehand group.All the screws (100％) were in the desired pedicle in the ball tip group and 215 (78％) in the conventional group.In the conventional group,23 screws(8.3％) were classified as medial violation; 38(13.7％) as lateral violation.A significant difference was determined between the 2 groups regarding the pedicle breaches.No vascular,pulmonary,or neurological injuries caused by pedicle screws placement was found in either group.ConclusionThis study demonstrates the accuracy and reliability of the ball tip probe technique in pedicle screw placement.This technique can probably reduce the risk of complications of screw misplacements.

BACKGROUND: Posterior lumbar non-fusion devices have been developed to control vertebral column movement, change load pattern of instability segment, restrict abnormal action, as well as avoid adjacent segment degeneration.OBJECTIVE: To investigate the efficiency of Wallis dynamic stabilization system in the treatment of lumbar vertebrae instability.METHODS: Ten cases suffering from lumbar instability were selected, including 3 males and 7 females, aged 43-65 years. One patient sustained L_(1/2) and L_(4/5) segmental instability, one was L_(2/3) and another was L_(3/4), and the others were L_(4/5). Two patients complicated with lumbar disc herniation and 7 patients combined with lumbar spinal stenosis at the same affected segment, and 3 patients associated with lumbar spinal stenosis at adjacent segment. All unstable segments were treated with decompression, posterior implantation of Wallis dynamic stabilization system. Visual analogue scale (VAS) and Japanese Orthopedic Association (JOA) scores for low back pain and Oswestry disability index (ODI) were used to evaluate clinical outcomes. In addition, therange of motion (ROM) at the instrumented segment and adjacent segments and posterior disc height (PDH) in standing and extension position at L_(4/5) segment were also measured.RESULTS AND CONCLUSION: All the patients were followed-up for 2-13 months, mean 9.2 months. The mean operation duration was 128 minutes (90-185 minutes), with bleeding volume of 264 Ml (50-600 Ml). Sings and symptoms of all patients were improved significantly after operation, except one patient with recurrence of L_(4/5) lumbar spinal stenosis at 3 month after surgery, whose symptoms relieved by revision with fenestration and decompression. The postoperative VAS was dramatically decreased than that of preoperation (P=0.003); the JOA score was obviously increased (P=0.002), and the ODI score was decreased (p=0.008). The postoperative range of motion decreased significantly (P<0.05). However, there was no obviously difference between preoperative and postoperative L_(3/4), L_5/S_1 and posterior disc height (P>0.05). Good clinical results can be achieved by surgical intervention with Wallis dynamic stabilization system in treating lumbar vertebrae instability.

Objective To evaluate the clinical efficacy of monosegmental pedicle instrumentation in management of thoracolumbar burst fractures. Methods A total of 67 patients with traumatic thora-columbar burst fractures (type A3.1 and A3.2) were treated with monosegmental pedicle instrumentation in our department from October 2003 to February 2008. Imageologic effect was observed by measuring sagittal index and wedge index via X-ray and clinical outcomes evaluated by using low back outcome score. Results All operations were performed successfully, with average operation duration of 93 mi-nutes and average intraoperative blood loss of 157 ml. Of all, 65 patients were followed up for 4-27 months (average 19.8 months), which showed that all the patients achieved bony fusion, with no implant failure except for one with screw loosening. The sagittal index and wedge index were 13.06°and 42.9% preoperatively and 4.47° and 21.78% postoperatively, with statistical difference (P <0.01). The final follow-up showed no significant correction loss except for two patients (P < 0.05). The low back outcome scores of all patients at follow-up were improved significantly (P < 0.05). Conclusions Monoseg-mental pedicle instrumentation has advantages of minimal invasion, short operative duration, less blood loss and less vertebral motion segment loss and hence is an effective and reliable operative technique for thoracolumbar burst fractures.

Objective To observe the ultrastructure of the neurovascular Unit (NVU) in chronic compressive cervical myelopathy rat model at different stages.Methods From March, 2014 to March, 2015, 32 rats were divided into two groups: sham control group (n =8) and compressive spinal cord injury group (n =24).The model was established by inserting the compression sheet made of polyurethane at the level of C6.BBB and somatosensory evoked potentials (SEP) were used to evaluate the spinal cord function status of model rat.Transmission Electron Microscopy (TEM) examination of compressive cervical spinal cords was performed separately at the 14th, 21st, 28th and 42nd day after modeling.Results At the 14th, 21st, 28th and 42nd, the BBB score were 17.571 ± 0.870, 15.952 ± 0.870, 15.476 ± 0.602 and 16.190 ± 0.632 were significantly lower than those in the control group (the BBB score of 4 points were 19.600 ± 0.516, 19.500 ± 0.527, 19.600 ± 0.699 and 19.800 ± 0.6232 respectively) (P ＜ 0.05).Latency prolongation and amplitude reduction of somatosensory evoked potentials (SEP) were presented in the compressive spinal cord injury group.At the 14th day, edema around the capillaries was observed, the morphological structure of endothelial cells and basement membrane was normal, the tight junction between endothelial cell was intact, the mitochondria in the axons, oligodendrocytes and astrocyte foot processes were edematous.At the 21st day, extensive edema, even partial necrosis around the capillaries were found, the surrounding structure were arranged loosely, partial loss of endothelial cells and basement membrane, cavitation occurrence in endothelial cells, basal membrane density was significantly lower, mitochondria vacuoles and shrinkage in the cytoplasm, axon myelin loose or broken;at the 28th day, the edematous range surrounding capillaries narrowed, low density of basement membrane and endothelial cells, vacuoles in endothelial cells, loose axon myelin, while some mitochondrias backed to normal.At the 42nd day, capillary integrity, no abnormalities were found in endothelial cells, basement membrane, tight junction and mitochondria, double layers of endothelial cells and basement membrane could be seen, local broken and loose structure were presented in part of the axons;The TEM of the sham control group showed normal ultrastructure of NVU.Conclusion The ultrastructure of NVU in chronic cervical spinal cord compression presented various in the different periods, NVU disruption were found in the early stages (14th-28th days), and compensatory and repair process were developed incompletely later.

Objective To evaluate the clinical outcome of mono-segment transpedicular fixation of type B thoracolumbar fracture.Methods A retrospective analysis was conducted on 40 cases suffering from type B thoracolumbar fracture treated with mono-segment transpedicular fixation from May 2003 to October 2012.According to the AO classification,13 cases were identified with type B1.1,11 type B1.2,11 type B2.2,2 type B3.1,2 type B3.2,and 1 type B3.3.Radiological results were evaluated by measuring compression rate of the fractured vertebra and Cobb' s angle of the vertebra adjacent to the fractured segment.Clinical results were assessed using Frankel classification for spinal cord injury and visual analogue scale (VAS) for pain.Results Mean operation time was 71 minutes and mean intrao perative blood loss was 105 ml.Mean period of follow-up was 47.5 months (range,24-82 months).Mean Cobb' s angle of the vertebra adjacent to the fractured segment and compression rate of the fractured vertebra revealed great correction at one week post-operation compared with preoperative ones (6.2° vs 20.1° and 10.1％ vs 38.9％ respectively,P ＜0.05) and there was no significant correction loss at the last follow-up (6.9° and 10.8％ respectively,P ＞ 0.05).Mean VAS was 8.6 points before operation,but mean VAS was 2.4 points at final follow-up (P ＜ 0.05).Neurological performance improved in 37 cases (93％).No cases experienced neurological deterioration.Conclusions Mono-segment transpedicular fixation has small incision,short operation time,few bleeding and decreased motor function loss.The procedure is indicated for most type B thoracolumbar fracture and clinical results are satisfactory.

Chronic spinal cord compression is the common clinical prognosis with various outcomes, but the affecting factors and mechanisms still remain unexplored. The structure and function of neurovascular unit manifest great significance in the central nervous system diseases. This paper discusses matrix metalloproteinase (MMP) impact on the stability of the neural vascular unit, by directly decomposing extracellular matrix, inducing the glial cell migration, activating angiogenesis, regulating function of blood spinal cord barrier, and put forward the MMP may be the key points in regulation of spinal cord neurovascular unit structure and function change to affect the outcome of chronic oppressive cervical spinal cord.
Cell Movement ; Humans ; Matrix Metalloproteinases ; physiology ; Nerve Compression Syndromes ; diagnosis ; enzymology ; Neurons ; cytology ; Prognosis ; Spinal Cord Injuries ; diagnosis ; enzymology

Objective To study the surgical indications and effectiveness of short segment pedicle screw fixation plus pecutaneous vertebroplasty (PVP) for single thoracolumbar fracture combined with Kümmell disease.Methods Between June 2012 and June 2014,a prospective case series analysis was made on the clinical data of 15 selected cases of single thoracolumbar fracture patients who were combined with Kümmell disease.There were three males and 12 females,with an average age of 62.5 years (range,48-80 years).The iujured vertebrae were located at T11 in 3 cases,at T12in 4,at L1 in 5 and at L2 in 3.All the patients were treated by short segment fixation plus PVP.Operative time,surgery-related complications and adjacent vertebral fracture during follow-up were recorded.The effectiveness of the treatment was appraised by visual analogue scale (VAS),Oswestry Disability Index (ODI),Cobb angle of operative segment,which were recorded preoperatively,one week post-operatively and at final follow-up.One-way ANOVA (Analysis of Variance) was employed for statistical analysis.Results The operative time was 0.8-2 hours (mean,1.35 hour).There was no observation of incision infection,nerve injury,cement leakage or other related operative complications.A total of 15 patients were followed up for 16-36 months (mean,22.4 months),which showed solid fusion and bone bridges in all patients,with no fracture of adjacent vertebra observed.VAS was improved from preoperative (5.93 ± 0.62) points to (1.80±0.64) points one week postoperatively and (2.60 ± 0.53) points at final follow-up.ODI was improved from preoperative 61.53 ± 4.30 to 19.93 ±3.26 one week postoperatively and 23.07 ± 4.06 at final follow-up.Cobb angle of operative segment was improved from preoperative (17.40 ± 6.73) ° to (9.53 ± 3.12) o one week postoperatively and (11.00 ± 3.20) ° at final follow-up.There was significant difference of all the indexes namely,VAS,ODI and Cobb angle,between preoperative and one week postoperative status as well as between preoperative and final follow-up (P ＜ 0.05 or 0.01).However,there was no significant difference between ODI and Cobb angle in one week postoperatively and at last follow-up (P ＞ 0.05).Conclusion For single thoracolumbar fracture with Kümmell disease,short segment fixation plus PVP can shorten the surgery time,reduce the rate of complications,relieve pain,recover the function and avoid loss of kyphosis correction,as is worthy of clinical recommendation.