Fang-Min Mao

Percutaneous pedicle screw fixation for neurologic intact thoracolumbar burst fractures.

Study Design Prospective consecutive series. Objective To evaluate the efficacy and safety of percutaneous pedicle screw fixation (PPSF) for thoracolumbar AO type A3 fractures with a specially designed surgical instrument system. Summary of Background Data Minimally invasive surgery including PPSF is becoming increasingly widespread in the spine surgery. The technique of PPSF was mostly used as supplemental fixation combined with minimally invasive posterior or anterior lumbar interbody fusion in management of lumbar degenerative disorders. There are fewer studies available in literature regarding PPSF without additional kyphoplasty or vertebroplasty for management of thoracolumbar burst fractures. Methods Thirty-six adult patients, who had single thoracolumbar AO type A3 fractures and the load-sharing score of 6 or less, underwent application of percutaneous short-segment pedicle screw fixation. Radiologic parameters including kyphotic angle and vertebral height loss were assessed before and after surgery, and functional outcome was evaluated by Prolo questionnaire. Results All patients were successfully managed with percutaneous minimal invasive procedures. The average operative time was 78 minutes (range 62 to 117 min). The average intraoperative blood loss was 75 mL (range 50 to 220 mL). After a mean follow-up of 48.5 months (range 32 to 63 mo), 31 of 36 (86.1%) patients had a satisfactory result (19 excellent and 12 good) and 5 of them fair. Conclusions Our clinical results suggest that PPSF can be an alternative for management of thoracolumbar AO type A3 fractures that have no neurologic deficits. With a specially designed percutaneous instrument and pedicle screw system, the procedure has been proved as relatively safe and a minimally invasive approach for the management of thoracolumbar burst fracture without neurologic deficit.

Fusion versus Nonfusion for Surgically Treated Thoracolumbar Burst Fractures: A Meta-Analysis

Background Posterior pedicle screw fixation has become a popular method for treating thoracolumbar burst fractures. However, it remains unclear whether additional fusion could improve clinical and radiological outcomes. This meta-analysis was performed to evaluate the effectiveness of fusion as a supplement to pedicle screw fixation for thoracolumbar burst fractures. Methodology/Principal Findings MEDLINE, OVID, Springer, and Google Scholar were searched for relevant randomized and quasi-randomized controlled trials that compared the clinical and radiological efficacy of fusion versus nonfusion for thoracolumbar burst fractures managed by posterior pedicle screw fixation. Risk of bias in included studies was assessed using the Cochrane Risk of Bias tool. We generated pooled risk ratios or weighted mean differences across studies. Based on predefined inclusion criteria, 4 eligible trials with a total of 220 patients were included in this meta-analysis. The mean age of the patients was 35.1 years. 96.8% of the fractures were located at T12 to L1 level. Baseline characteristics were similar between the fusion and nonfusion groups. No significant difference was identified between the two groups regarding radiological outcome, functional outcome, neurologic improvement, and implant failure rate. The pooled data showed that the nonfusion group was associated with significantly reduced operative time (p<0.0001) and blood loss (p  = 0.0003). Conclusions/Significances The results of this meta-analysis suggested that fusion was not necessary when thoracolumbar burst fracture was treated by posterior pedicle screw fixation. More randomized controlled trials with high quality are still needed in the future.

Microendoscopic anterior approach for irreducible atlantoaxial dislocation: surgical techniques and preliminary results.

Study Design Surgical techniques and preliminary results. Objective To describe and evaluate the safety and efficacy of a new minimal invasive technique for the irreducible atlantoaxial dislocation (IADD). Summary of Background Data Endoscope has been widely used in minimal invasive spinal surgery. However, there are no clinical reports regarding anterior approach for IADD in the literature. Methods Ten consecutive patients with IADD were treated by anterior release with microendoscopic aide and subsequently reduction, anterior transarticular screw fixation and morselized autologous bone grafts. There were 3 cases of odontiod dysplasia, 4, chronic odontiod fracture, 1, odontiod absence, 1 fasilar impression, and 1 malunion of odontoid fracture. According to Symon and Lavenders classification of disability, 6 cases were moderate disability, 3 severe nonbedbound, and 1 severe bedridden. The procedure was performed by the same surgeon (Yong-Long Chi). Results The new technique was performed successfully in all cases. All the patients underwent transarticular screw fixation and anterior morselized autograft fusion. The average operation time was 120 min (range, 90 to 150 min) and the mean estimated blood loss was 150 mL (range, 100 to 250 mL). Postoperative radiographs demonstrated that 9 cases restored anatomic position and 1 had partial reduction. According to the postoperative computed tomography all the screws were appropriately placed. Follow-up after surgery, longest is 16 months and minimal 8 months with a mean of 12 months, neurologic status was improved in all patients. There was no loss of fixation and solid fusion was achieved in all cases. Conclusions Surgical technique of microendoscopic anterior release, reduction, fixation, and fusion is safe and reliable minimally invasive for treating IADD.

Percutaneous anterior transarticular screw fixation for atlantoaxial instability: A CASE SERIES

We reviewed the outcome of a retrospective case series of eight patients with atlantoaxial instability who had been treated by percutaneous anterior transarticular screw fixation and grafting under image-intensifier guidance between December 2005 and June 2008. The mean follow-up was 19 months (8 to 27). All eight patients had a solid C1-2 fusion. There were no breakages or displacement of screws. All the patients with pre-operative neck pain had immediate relief from their symptoms or considerable improvement. There were no major complications. Our preliminary clinical results suggest that percutaneous anterior transarticulation screw fixation is technically feasible, safe, useful and minimally invasive when using the appropriate instruments allied to intra-operative image intensification, and by selecting the correct puncture point, angle and depth of insertion.

Pooled Analysis of Non-Union, Re-Operation, Infection, and Approach Related Complications after Anterior Odontoid Screw Fixation

Background Anterior odontoid screw fixation (AOSF) has been one of the most popular treatments for odontoid fractures. However, the true efficacy of AOSF remains unclear. In this study, we aimed to provide the pooled rates of non-union, reoperation, infection, and approach related complications after AOSF for odontoid fractures. Methods We searched studies that discussed complications after AOSF for type II or type III odontoid fractures. A proportion meta-analysis was done and potential sources of heterogeneity were explored by meta-regression analysis. Results Of 972 references initially identified, 63 were eligible for inclusion. 54 studies provided data regarding non-union. The pooled non-union rate was 10% (95% CI: 7%–3%). 48 citations provided re-operation information with a pooled proportion of 5% (95% CI: 3%–7%). Infection was described in 20 studies with an overall rate of 0.2% (95% CI: 0%–1.2%). The main approach related complication is postoperative dysphagia with a pooled rate of 10% (95% CI: 4%–17%). Proportions for the other approach related complications such as postoperative hoarseness (1.2%, 95% CI: 0%–3.7%), esophageal/retropharyngeal injury (0%, 95% CI: 0%–1.1%), wound hematomas (0.2%, 95% CI: 0%–1.8%), and spinal cord injury (0%, 95% CI: 0%–0.2%) were very low. Significant heterogeneities were detected when we combined the rates of non-union, re-operation, and dysphagia. Multivariate meta-regression analysis showed that old age was significantly predictive of non-union. Subgroup comparisons showed significant higher non-union rates in age ≥70 than that in age ≤40 and in age 40 to <50. Meta-regression analysis did not reveal any examined variables influencing the re-operation rate. Meta-regression analysis showed age had a significant effect on the dysphagia rate. Conclusions/Significances This study summarized the rates of non-union, reoperation, infection, and approach related complications after AOSF for odontoid factures. Elderly patients were more likely to experience non-union and dysphagia.

Comparison of Cervical Spine Anatomy in Calves, Pigs and Humans.

Background Context Animals are commonly used to model the human spine for in vitro and in vivo experiments. Many studies have investigated similarities and differences between animals and humans in the lumbar and thoracic vertebrae. However, a quantitative anatomic comparison of calf, pig, and human cervical spines has not been reported. Purpose To compare fundamental structural similarities and differences in vertebral bodies from the cervical spines of commonly used experimental animal models and humans. Study Design Anatomical morphometric analysis was performed on cervical vertebra specimens harvested from humans and two common large animals (i.e., calves and pigs). Methods Multiple morphometric parameters were directly measured from cervical spine specimens of twelve pigs, twelve calves and twelve human adult cadavers. The following anatomical parameters were measured: vertebral body width (VBW), vertebral body depth (VBD), vertebral body height (VBH), spinal canal width (SCW), spinal canal depth (SCD), pedicle width (PW), pedicle depth (PD), pedicle inclination (PI), dens width (DW), dens depth (DD), total vertebral width (TVW), and total vertebral depth (TVD). Results The atlantoaxial (C1–2) joint in pigs is similar to that in humans and could serve as a human substitute. The pig cervical spine is highly similar to the human cervical spine, except for two large transverse processes in the anterior regions ofC4–C6. The width and depth of the calf odontoid process were larger than those in humans. VBW and VBD of calf cervical vertebrae were larger than those in humans, but the spinal canal was smaller. Calf C7 was relatively similar to human C7, thus, it may be a good substitute. Conclusion Pig cervical vertebrae were more suitable human substitutions than calf cervical vertebrae, especially with respect to C1, C2, and C7. The biomechanical properties of nerve vascular anatomy and various segment functions in pig and calf cervical vertebrae must be considered when selecting an animal model for research on the spine.

Application of the Coflex Interlaminar Stabilization in Patients With L5/S1 Degenerative Diseases: Minimum 4-Year Follow-up.

The Coflex is one of the representatives of posterior dynamic interspinous process device, but no study with the application of Coflex interlaminar stabilization in L5/S1 level has been performed. The aim of this study was to evaluate the feasibility and validity of the Coflex interlaminar stabilization in the treatment of degenerative lumbar diseases on L5/S1 level. A retrospective study was conducted for a consecutive series of 33 patients with degenerative lumbar spinal stenosis or lumbar disc herniation located in L5/S1 between November 2007 and September 2010. Subjects were all received decompressive laminectomy with implantation of Coflex device. Clinical effects were evaluated by visual analog scale and Oswestry Disability Index. Radiographs were done preoperatively, postoperatively, and at final follow-up. The Coflex devices were successfully implanted in all subjects. Fourteen cases completed the operations by inverting the prosthesis on account of too short S1 spinous processes. During the minimum 4-year follow-up period, all patients had obvious improvement in clinical effects (P < 0.05). Radiological evaluation revealed that dorsal intervertebral space height and intervertebral foramen height of target level increased significantly in all cases postoperatively and maintained well to final follow-up. In addition, the sagittal range of motion of operated level was restricted (P < 0.05), and the range of motion of adjacent segment did not change much (P > 0.05). The Coflex is an efficacious dynamic interspinous process device for the treatment of degenerative lumbar diseases that can apply to L5/S1.

Transforaminal Decompression and Interbody Fusion in the Treatment of Thoracolumbar Fracture and Dislocation with Spinal Cord Injury

Study Design A retrospective clinical study. Objective To evaluate the efficacy and safety of transforaminal decompression and interbody fusion in the treatment of thoracolumbar fracture and dislocation with spinal cord injury. Methods Twenty-six spinal cord injured patients with thoracolumbar fracture and dislocation were treated by transforaminal decompression and interbody fusion. The operation time, intraoperative blood loss, and complications were recorded; the Cobb angle and compressive rate (CR) of the anterior height of two adjacent vertebrae were measured; and the nerve injury was assessed according to sensory scores and motor scores of the American Spinal Injury Association (ASIA) standards for neurological classification of spinal cord injury. Results The operative time was 250±57 min, and intraoperative blood loss was 440±168 ml. Cerebrospinal leakage was detected and repaired during the operation in two patients. A total of 24 of 26 patients were followed up for more than 2 years. ASIA sensory scores and motor scores were improved significantly at 3 months and 6 months after operation; the Cobb angle and CR of the anterior height of two adjacent vertebrae were corrected and showed a significant difference at post-operation; and the values were maintained at 3 months after operation and the last follow-up. Conclusion We showed that transforaminal decompression together with interbody fusion is an alternative method to treat thoracolumbar fracture and dislocation.