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Hui Liu, Zemin Li, Sibei Li, Kuibo Zhang, Hao Yang, Jianru Wang, Xiang Li and Zhaomin Zheng

OBJECT

The aim of this study was to evaluate the effects of rod stiffness and implant density on coronal and sagittal plane correction in patients with main thoracic curve adolescent idiopathic scoliosis (AIS).

METHODS

The authors conducted a retrospective study of 77 consecutive cases involving 56 female and 21 male patients with Lenke Type 1 main thoracic curve AIS who underwent single-stage posterior correction and instrumented spinal fusion with pedicle screw fixation between July 2009 and July 2012. The patients' mean age at surgery was 15.79 ± 3.21 years. All patients had at least 1 year of follow-up. Radiological parameters in the coronal and sagittal planes, including Cobb angle of the major curve, side-bending Cobb angle of the major curve, thoracic kyphosis (TK), correction rates, and screw density, were measured and analyzed. Screw densities (calculated as number of screws per fusion segment × 2) of < 0.60 and ≥ 0.60 were defined as low and high density, respectively. Titanium rods of 5.5 mm and 6.35 mm diameter were defined as low and high stiffness, respectively. Patients were divided into 4 groups based on the type of rod and density of screw placement that had been used: Group A, low-stiffness rod with low density of screw placement; Group B, low-stiffness rod with high density of screw placement; Group C, high-stiffness rod with low density of screw placement; Group D, high-stiffness rod with high density of screw placement.

RESULTS

The mean coronal correction rate of the major curve, for all 77 patients, was (81.45% ± 7.51%), and no significant difference was found among the 4 groups (p > 0.05). Regarding sagittal plane correction, Group A showed a significant decrease in TK after surgery (p < 0.05), while Group D showed a significant increase (p < 0.05); Group B and C showed no significant postoperative changes in TK (p > 0.05). The TK restoration rate was highest in Group D and lowest in Group A (A, −39.32% ± 7.65%; B, −0.37% ± 8.25%; C, −4.04% ± 6.77%; D, 37.59% ± 8.53%). Screw density on the concave side was significantly higher than that on the convex side in all the groups (p < 0.05).

CONCLUSIONS

For flexible main thoracic curve AIS, both rods with high stiffness and those with low stiffness combined with high or low screw density could provide effective correction in the coronal plane; rods with high stiffness along with high screw density on the concave side could provide better outcome with respect to sagittal TK restoration.

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Ming-Xiang Zou, Jing Li, Xiao-Bin Wang and Guo-Hua Lv

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Jun Wang, Xin-Feng Liu, Bao-Min Li, Sheng Li, Xiang-Yu Cao, Yong-Ping Liang, Ai-Li Ge and Hui-Min Feng

OBJECTIVE

Large vertebrobasilar fusiform aneurysms (VFAs) represent a small subset of intracranial aneurysms and are often among the most difficult to treat. Current surgical and endovascular techniques fail to achieve a complete or acceptable result because of complications, including late-onset basilar artery thrombosis and perforator infarction. The parallel-stent placement technique was established in the authors' department, and this study reports the application of this technique in the treatment of unruptured VFAs.

METHODS

Eight patients with 8 unruptured VFAs who underwent parallel stent placement between April 2011 and August 2012 were included. The diameters of the VFAs ranged from 7.9 to 14.0 mm, and the lengths from 27.5 to 54.4 mm. Of the 8 patients with unruptured VFAs, 3 received double or triple parallel stents and 5 patients received a series-connected stent with another 1 or 2 stents deployed parallel to them. Outcomes for these patients were tabulated, based on the modified Rankin Scale (mRS) score and angiographic results.

RESULTS

All of the 25 stents were successfully placed without any treatment-related complications. During follow-up, 5 patients had decreased mRS scores, 2 were unchanged, and 1 was increased for subarachnoid hemorrhage. Immediate and follow-up clinical outcome was completely or partially recovered in most patients. Follow-up angiograms revealed 2 aneurysms were reduced in size and 6 were unchanged after stent placement. No in-stent stenosis, occlusion of the posterior inferior cerebellar artery, or perforators jailed by the stent occurred in any of the aneurysms.

CONCLUSIONS

These results provide encouraging support for the parallel-stent placement technique, which can be envisaged as an alternative strategy against unruptured VFAs. However, testing in more patients is needed.

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J. J. Verlaan and F. C. Oner

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Hongwei Wang, Yue Zhou, Changqing Li, Jun Liu and Liangbi Xiang

OBJECT

Few studies have addressed surgical failures and complications following percutaneous endoscopic lumbar discectomy (PELD), and no previous study has investigated the risk factors that lead to surgical failure. The authors report their experience using PELD for single-level lumbar disc herniation (LDH) to provide insights into the rates of surgical failure and identify potential risk factors that lead to this complication.

METHODS

The authors retrospectively reviewed the medical records of 350 patients who underwent PELD for single-level LDH and identified 36 patients (10.3%) who underwent reoperation due to the failure of PELD.

RESULTS

Patients’ mean visual analog scale of pain scores and Oswestry Disability Index scores improved significantly from 6.6 ± 2.1 and 51.6 ± 19.4 preoperatively to 1.9 ± 1.4 and 28.3 ± 12.0, respectively, at 1 month postoperatively and 1.2 ± 1.1 and 9.3 ± 7.8, respectively, at 1 year postoperatively. The frequencies with which patients took analgesic medications significantly decreased from 74.6% preoperatively to 19.7% at 1 month postoperatively and 10.0% at 1 year postoperatively. Relatively older patients (p = 0.005) and those ≥ 60 years old (p = 0.001) experienced larger numbers of failures compared to younger patients. An analysis of potentially contributing comorbid conditions indicated that significantly more patients with diabetes were present in the PELD failure group (p = 0.017). As surgeons gained familiarity with the procedure, outcomes improved. The failure rate during the authors’ early use of the PELD technique (Cases 1–70) was 17.1%; the failure rate then fell to 5.7% (p = 0.034) (Cases 141–210) before finally stabilizing at 10.0% (Cases 211–280 and Cases 281–350).

CONCLUSIONS

The surgical failure rate following PELD for LDH was 10.3%. Older patients, elderly patients (age ≥ 60 years), and patients with diabetes were at increased risk of surgical failure of PELD, particularly in the early years of the procedure’s use.

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Xiang-Yang Wang, Li-Yang Dai, Hua-Zi Xu and Yong-Long Chi

Object.

Experimental burst fracture models are often developed by using either single or incremental impacts. In both protocols, the weight-drop technique produces the impact. However, to the authors' knowledge in no study have researchers attempted to compare the equivalence of the spine burst fracture produced using the different impact protocols. This study was performed to investigate whether the single and incremental trauma approaches produce equivalent degrees of severity in thoracolumbar burst fractures.

Methods.

Twenty bovine thoracolumbar spines comprising three vertebrae were divided evenly into the single impact and incremental impact groups. The specimens in the incremental impact group were subjected to three axial compressive impacts of increasing energy (78.4, 107.8, and 137.2 J), whereas specimens in the other group were subjected to a single impact (137.2 J). Before and after the final trauma, multidirectional flexibility of each specimen was measured under flexion/extension, right/left lateral bending, and right/left axial rotation, thus quantifying the instability of the fracture. The flexibility parameters were then compared between the two groups.

Results.

A significant increase in flexibility parameters was found after the final trauma in both groups, indicating the instability of the spine (p < 0.01). No significant differences in flexibility parameters were observed in either intact status or injured status between the two groups (p > 0.05).

Conclusions.

In this study the authors have confirmed that the single and incremental impact protocols produced a similar degree of severity in producing an in vitro bovine burst fracture. The results of this study support the use of the incremental impact protocol in future experimental biomechanical studies.

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Hongwei Wang, Yuan Zhang, Qiang Xiang, Xuke Wang, Changqing Li, Hongyan Xiong and Yue Zhou

Object

The main objective of this study was to analyze the epidemiological data obtained from patients with traumatic spinal fracture at 2 university-affiliated hospitals in Chongqing, China.

Methods

The authors retrospectively reviewed the hospital records of all patients who suffered traumatic spinal fracture and were treated at Xinqiao Hospital and Southwest Hospital (both affiliated with The Third Military Medical University) between January 2001 and December 2010. The demographic characteristics, injury characteristics, and clinical outcomes of patients over this 10-year period were compared.

Results

A total of 3142 patients (mean age 45.7 years, range 1–92 years) with traumatic spinal fractures were identified; 65.5% of the patients were male. The peak frequency of these injuries occurred in the 31- to 40-year-old age group. Accidental falls and traffic accidents were the most common causes of spinal fractures (58.9% and 20.9%, respectively). Traffic accidents tended to occur in younger patients, whereas accidental falls tended to occur in older patients. The most common area of fracture was the thoracolumbar spine (54.9%). Cervical spinal fractures were significantly more common in patients injured in traffic accidents, while lumbar spinal fractures were more common in accidental fall patients. Using the American Spinal Injury Association (ASIA) classification, 479 (15.3%) patients were classified as having ASIA A injuries; 913 (29.1%), ASIA B, ASIA C, or ASIA D; and 1750 (55.7%), ASIA E. ASIA A injuries were more common in patients who suffered thoracic spinal fractures (15.09%) than in those with fractures in other areas of the spine. A total of 954 (30.4%) patients had associated nonspinal injuries. Of these patients, 389 (40.78%) suffered a thoracic injury, and 191 (20.02%) sustained a head and neck injury. The length of hospitalization differed significantly between the accidental falls from high heights and falls from low heights, as did the mean cost of hospitalization (p < 0.05), but no significant difference was found between accidental falls from high heights and traffic accidents (p > 0.05). The length of hospitalization differed significantly among the 3 groups according to the ASIA classification, as did the mean cost of hospitalization (p < 0.05). Of patients with incomplete lesions, 39.3% improved 1 or more grades in ASIA classification during hospitalization.

Conclusions

Accidental falls emerged as the leading cause of traumatic spinal fracture in this study, and the numbers of fall-induced and sports-related injuries increased steadily with age. These results indicate that there should be increased concern for the consequences of fall- and sports-related injuries among the elderly.

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Yu Han, Jianguang Sun, Chenghan Luo, Shilei Huang, Liren Li, Xiang Ji, Xiaozong Duan, Zhenqing Wang and Guofu Pi

OBJECTIVE

Pedicle screw–based dynamic spinal stabilization systems (PDSs) were devised to decrease, theoretically, the risk of long-term complications such as adjacent-segment degeneration (ASD) after lumbar fusion surgery. However, to date, there have been few studies that fully proved that a PDS can reduce the risk of ASD. The purpose of this study was to examine whether a PDS can influence the incidence of ASD and to discuss the surgical coping strategy for L5–S1 segmental spondylosis with preexisting L4–5 degeneration with no related symptoms or signs.

METHODS

This study retrospectively compared 62 cases of L5–S1 segmental spondylosis in patients who underwent posterior lumbar interbody fusion (n = 31) or K-Rod dynamic stabilization (n = 31) with a minimum of 4 years' follow-up. The authors measured the intervertebral heights and spinopelvic parameters on standing lateral radiographs and evaluated preexisting ASD on preoperative MR images using the modified Pfirrmann grading system. Radiographic ASD was evaluated according to the results of radiography during follow-up.

RESULTS

All 62 patients achieved remission of their neurological symptoms without surgical complications. The Kaplan-Meier curve and Cox proportional-hazards model showed no statistically significant differences between the 2 surgical groups in the incidence of radiographic ASD (p > 0.05). In contrast, the incidence of radiographic ASD was 8.75 times (95% CI 1.955–39.140; p = 0.005) higher in the patients with a preoperative modified Pfirrmann grade higher than 3 than it was in patients with a modified Pfirrmann grade of 3 or lower. In addition, no statistical significance was found for other risk factors such as age, sex, and spinopelvic parameters.

CONCLUSIONS

Pedicle screw–based dynamic spinal stabilization systems were not found to be superior to posterior lumbar interbody fusion in preventing radiographic ASD (L4–5) during the midterm follow-up. Preexisting ASD with a modified Pfirrmann grade higher than 3 was a risk factor for radiographic ASD. In the treatment of degenerative diseases of the lumbosacral spine, the authors found that both of these methods are feasible. Also, the authors believe that no extra treatment, other than observation, is needed for preexisting degeneration in L4–5 without any clinical symptoms or signs.

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Xiang-Yang Wang, Li-Yang Dai, Hua-Zi Xu and Yong-Long Chi

Object

Recurrent kyphosis has been commonly seen after posterior short-segment pedicle instrumentation for a thoracolumbar fracture, but studies on this issue are relatively scarce, and the clinical significance of recurrent deformity is uncertain. No study has addressed the associations between the reduction of a burst fracture vertebra and the final recurrent kyphosis after implant removal. The aim of this study was to investigate the recurrent kyphosis after short-segment pedicle screw fixation in thoracolumbar burst fractures and to evaluate the effect of the degree of a vertebral reduction on the recurrent kyphotic deformity after implant removal.

Methods

Twenty-seven patients who had undergone posterior short-segment pedicle screw fixation for thoracolumbar junction burst fractures (T12–L2) were investigated retrospectively. The minimum follow-up period was 2 years (mean 2.7 years). Pain status was evaluated using the Denis pain scale. Changes in the anterior vertebral height ratio, vertebral wedge angle, upper intervertebral angle, lower intervertebral angle, Cobb angle, regional angle, and sagittal index were measured preoperatively, postoperatively, before implant removal, and at final follow-up. The correlation between the reduction of a fractured vertebra and the recurrent kyphotic deformity was also analyzed.

Results

After the initial surgical correction, the reduced vertebral body (VB) height (anterior vertebral height ratio and vertebral wedge angle) remained stable until final follow-up, whereas the intervertebral disc space (the upper and lower intervertebral angles) collapsed, resulting in a progressive kyphotic deformity (Cobb angle, regional angle, and sagittal index). No significant correlation was found between the final kyphosis and pain scale, but the 8 patients with a sagittal index > 15° showed a higher incidence of moderate to severe pain (P3–5 on the Denis pain scale) compared with the remaining 19 patients with a sagittal index < 15°. Significant positive correlation was found between recurrent kyphosis and vertebral wedge angle (r = 0.850, p < 0.001) and the reduced vertebral height (r = −0.727, p < 0.001).

Conclusions

Given that the correction loss occurs primarily through disc space collapse, the amount of the final kyphotic deformity was predictable by the degree of the fractured vertebral reduction as seen on the lateral x-ray study. Surgeons who perform posterior reduction and fixation procedures should pay more attention to reducing the fractured vertebral wedge angle to its intact condition, rather than the segmental angular parameters. If the wedge angle of the fractured VB is unacceptable after reduction, additional reconstruction of the anterior column may be necessary.

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Qian-Nan Wang, Xiang-Yang Bao, Yong Zhang, Qian Zhang, De-Sheng Li and Lian Duan

OBJECTIVE

The objective of this study was to investigate long-term outcomes after encephaloduroarteriosynangiosis (EDAS) for the treatment of hemorrhagic moyamoya disease (MMD) and identify the risk factors for recurrent hemorrhages.

METHODS

The authors retrospectively reviewed 95 patients with hemorrhagic MMD who were treated with EDAS at 307th Hospital PLA. Clinical features, angiographic findings, and clinical outcomes were investigated. Rebleeding incidences were compared between anterior or posterior hemorrhagic sites. Kaplan-Meier survival analysis and Cox proportional hazards regression models were used to estimate rebleeding risks after EDAS.

RESULTS

The average age at symptom onset was 37.1 years (range 20–54 years) for adult patients. The ratio of female to male patients was 1.16:1. In 61 of 95 hemorrhagic hemispheres (64.2%), the anterior choroidal artery (AChA) or posterior communicating artery (PCoA) was extremely dilated, with extensive branches beyond the choroidal fissure, which only occurred in 28 of 86 nonhemorrhagic hemispheres (32.6%). Fifty-seven incidences were classified as anterior hemorrhages and 38 as posterior. Sixteen of 95 patients (16.8%) suffered cerebral rebleeding after a median follow-up duration of 8.5 years. The annual rebleeding rate was 2.2% per person per year. The incidence rate was higher for the posterior group than for the anterior group, but this difference was not statistically significant (p > 0.05). Cox regression analysis revealed that the age of symptom onset (OR 1.075, 95% CI 1.008–1.147, p = 0.028) was a predictor of rebleeding strokes.

CONCLUSIONS

Through long-term follow up, EDAS proved beneficial for patients with hemorrhagic MMD. Dilation of the AChA-PCoA is associated with the initial hemorrhage of MMD, and rebleeding is age-related. Patients with hemorrhagic MMD should undergo follow-up over the course of their lives, even when neurological status is excellent.