Segmental Fixation Research Articles

Effectiveness comparison between two operations in treatment of unstable type Kümmell's disease

To compare the effectiveness between short segmental fixation combined with vertebroplasty (SSF+VP) and short segmental pedicle screw fixation combined with bone graft (SSF+BG) in the treatment of unstable type Kümmell's disease so as to provide a reference for the selection of the surgical method. Between March 2013 and February 2015, 48 patients with unstable type Kümmell's disease who were in accordance with the inclusive criteria were included in the study. SSF+VP were used in 25 cases (SSF+VP group) and SSF+BG in 23 cases (SSF+BG group). There was no significant difference in gender, age, disease duration, bone mineral density, fracture segment, and preoperative visual analogue scale (VAS), Oswestry disability index (ODI), and kyphotic Cobb angle between 2 groups ( P>0.05). The operation time and complications related to operation were recorded; the effectiveness was evaluated by VAS, ODI, and kyphotic Cobb angle. The operation time was (107.7±18.8) minutes in SSF+VP group and was (113.7±22.4) minutes in SSF+BG group, showing no significant difference between 2 groups ( t=-1.045, P=0.302). Bone cement leakage occurred in 6 cases of SSF+VP group, and incision delayed healing occurred in 1 case of SSF+BG group. All patients achieved bone graft fusion on X-ray films. The bone graft fusion time was (15.1±1.3) weeks in SSF+VP group and (15.7±1.8) weeks in SSF+BG group, showing no significant difference between 2 groups ( t=-1.361, P=0.180). The VAS, ODI, and kyphotic Cobb angle at immediate after operation and at last follow-up were significantly lower than preoperative ones ( P<0.05). The VAS, ODI, and kyphotic Cobb angle had no significant difference between at immediate and at last follow-up in SSF+VP group ( P>0.05). In SSF+BG group, VAS at last follow-up was significantly lower than that at immediate after operation ( P<0.05), but no significant difference was found in kyphotic Cobb angle and ODI ( P>0.05). SSF+VP group was significantly better than SSF+BG group in VAS at immediate after operation ( P<0.05), but SSF+BG group was significantly better than SSF+VP group at last follow-up ( P<0.05). There was no significant difference in kyphotic Cobb angle and ODI between 2 groups at immediate after operation and at last follow-up ( P>0.05). SSF+BG can achieve satisfactory effectiveness in the treatment of unstable type Kümmell's disease, and it has the advantages of good bony healing, obvious improvement of pain, and low complication incidence when compared with SSF+VP.

Short Same-Segment Instrumentation of Burst Thoracolumbar Fractures

Background Data: Long segment fixation has been frequently used for management of burst thoracolumbar fractures of the spine. Concerns about lost motion segments with this type of fixation encouraged the use of a shorter fixation method.Purpose: The aim of this study is to assess the ability of short segment fixation with pedicle screws at the fractured level to correct deformity, maintain correction and prevent failure in comparison to the traditional long segment fixation.Study Design: A descriptive retrospective clinical case study involving 40 patients.Patients and Methods: Forty patients underwent stabilization for unstable thoracolumbar burst fractures. They were divided into two groups; the short segment group and the long segment group. They were operated between June 2012 and May 2016. Participants were evaluated pre-operatively, post-operatively and at 3, 6, 9, and 12 months. Clinical outcome was compared using the modified Mc Nab criteria. Radiological outcome was compared using the Cobb angle measurement of kyphosis.Results: The two groups were fairly homogeneous and comparable epidemiologically. About 45% of the fractures were at L1 level. The short segment group showed less intraoperative blood loss, shorter operative time and hospital stay. Patients in both groups achieved satisfactory clinical outcome. No difference between the two groups in the mean kyphotic angle correction and the loss of kyphosis correction during follow up. Implant failure was recognized in five patients (12.5%), three patients had short segment fixation and two had long segment fixation.Conclusion: Short-segment pedicle screw fixation including the fractured vertebral body is as effective as long-segment pedicle screw fixation for the treatment of unstable thoracolumbar burst fracture. (2016ESJ137)

Comparative evaluation of bite force analytical study following mandibular osteosysthesis using three-dimensional and conventional locking miniplates.

Aims and Objectives:The aim is to study the effectiveness of 2 mm three-dimensional (3D) titanium miniplates and 2 mm conventional titanium miniplates in osteosynthesis of mandibular fractures by comparing the change in bite force.Methodology:The study comprised forty patients of age group 20–40 years, weighing 55–75 kg having mandibular fractures. Patients were randomly divided into two equal groups In Group A, twenty patients underwent osteosynthesis using 3D titanium miniplates (2.0 mm system), whereas in Group B, twenty patients underwent osteosynthesis using conventional titanium miniplates (2.0 mm system). After fixation of fracture segments with miniplates, the patients were assessed on the basis of evaluation of bite force at incisor, right molar and left molar region after 1, 3, 6 , and 8 weeks. Comparison of change in bite force was done between Group A and Group B at different follow-ups at incisor, right molar, and left molar.Results:Bite force recordings showed increasing values at subsequent follow-ups, corresponding to the healing of the fracture in both groups. At follow-up III (6 weeks) and IV (8 weeks), bite force values reached near to those in healthy individuals. A significant difference was observed in change in bite force of Group A and Group B at incisor left molar and right molar on subsequent followups. 3D titanium miniplate requires less surgical exposure of the underlying fracture site, with a minimal traction of the surrounding soft tissue.Interpretation and Conclusion:3D miniplates in mandibular fractures are efficacious enough to bear masticatory loads during the osteosynthesis of fractures. It gives the advantage of greater stability, increased bite force, reduced implant material, and 3D stability.

Only spinal fixation as treatment of prolapsed cervical intervertebral disc in patients presenting with myelopathy.

Aim:An alternative form of surgical treatment of prolapsed cervical intervertebral disc in patients presenting with symptoms related to myelopathy is discussed. The treatment involved fixation of the affected spinal segments and aimed at arthrodesis. No direct manipulation or handling of the disc was done.Materials and Methods:During the period August 2010 to June 2017, 16 patients presenting with symptoms attributed to myelopathy and diagnosed to have prolapsed cervical intervertebral disc were surgically treated by spinal stabilization. There were 11 males and 5 females and their ages ranged from 20 to 66 years (average: 40.6 years). Apart from clinical and radiological indicators, the number of spinal segments that were stabilized depended on direct observation of facetal morphology, alignment, and stability. Surgery involved distraction-fixation of facets using Goel facet spacer (8 patients), transarticular facetal fixation (5 patients) using screws or a combination of both facetal spacer, and transarticular screws (3 patients).Results:All patients had “remarkable” clinical improvement in the immediate postoperative period as assessed by visual analog scale, Goel's clinical grading, and Japanese Orthopedic Association scores. Follow-up ranged from 3 to 84 months (average: 50 months). The herniated disc regressed or disappeared at follow-up radiological assessment that ranged from 24 h to 3 months after surgery.Conclusions:Spinal segmental fixation aiming at arthrodesis with or without distraction of facets and without any direct surgical manipulation in the disc space or removal of the prolapsed portion of the disc can be considered in the armamentarium of the surgeon.

Robotics in the MIS Spine Surgery Arena: A New Role to Advance the Adoption of Endoscopic Surgery as the Least Invasive Spine Surgery Procedure

The role of robotics is gaining prominence as the technology of the future. In traditional spine surgery, accuracy of hardware placement, selection of ideal size and length of implanted screws and hardware for segmental fixation is desired and important even for experienced surgeons. Hardware placement in tight spaces is especially critical in the cervical and thoracic spine. Robotics will enhance patient safety as well as surgical results, for the protection of patients. By reducing surgical radiation exposure, it also protects patients as well as the surgeon and OR personnel. In endoscopic surgery, improving the accuracy of endoscopic trajectories with image guidance will also bring this aspect of MIS surgery to the surgical mainstream. Robotic techniques are evolving rapidly. Even in their current State of the Art, robotics offer significant advantages to the outpatient spinal surgeon by precise reproducible placement of hardware and endoscopes for minimally invasive approaches.

頚椎椎弓根スクリュー (CPS) 刺入精度の変遷

Objective : Cervical pedicle screw (CPS) may be the best anchor system for posterior cervical segmental fixation, but may carry high surgery-related risks such as neurovascular injury. The purpose of this study was to evaluate the accuracy of CPS placement by using various techniques such as a free-hand, computer navigation system.

Mandibular stability using sliding or conventional four-hole plates for fixation after bilateral sagittal split ramus osteotomy for mandibular setback

Our aim was to compare the postoperative stability of the mandible when two different fixation methods had been used after bilateral sagittal split ramus osteotomy (BSSRO) for mandibular setback. The study included 23 patients who had two-jaw BSSRO mandibular setback at the Department of Oromaxillofacial Surgery, Korea University Guro Hospital, between January 2011 and June 2014. The first group (four-hole (control) group, n=13) comprised patients whose bony segments were fixed with conventional four-hole plates, and the second (sliding plate (experimental) group, n=10) included patients whose bone segments were fixed with sliding plates. Lateral cephalograms were taken and analysed at three time points: preoperatively (T1), and one week (T2), and 1year (T3) postoperatively. The Mann–Whitney U test was used to compare the postoperative stability of the mandible in each group. There were no significant differences between the two groups in changes in the horizontal and vertical positions of point B and pogonion postoperatively, nor were there any significant differences between them in ramal inclination and inclination of the SN plane with point B at the given time points (p=>0.05 in surgical changes in the mandible immediately after surgery and 0.397, 0.616, 0.082, 0.951, 0.901, 0.476 in postoperative changes in the mandible 1 week to 1 year after surgery). Like the conventional four-hole plate, the sliding plate can also be used to achieve stability in the fixation of mandibular bone segments after BSSRO.

Effect of mono- or bisegmental lordosizing fusion on short-term global and index sagittal balance: a radiographic study.

Sagittal balance is widely recognized as an important outcome factor in reconstructive spinal surgery for lumbar degenerative conditions. However, its role in short segmental fixation is unknown. The aim of this study was to evaluate the preoperative and short-term postoperative spino-pelvic balance after short (1 or 2 levels) lordosizing lumbar fusion for degenerative disc disease (DDD). Twenty-six consecutive patients (13 males and 13 females) undergoing mono- or bisegmental lordosizing lumbar fusion (XLIF/TLIF) for lumbar DDD were included in the study. Clinical parameters were retrospectively collected from charts. Preoperative and early postoperative (6 weeks and 3 months) full-spine EOS X-rays were evaluated. Spinal parameters evaluating sagittal curvatures, pelvic orientation, global sagittal and coronal alignment, spino-pelvic balance, index level segmental lordosis and disc height were measured and statistically analyzed. A total of 16 TLIF and 10 XLIF procedures were performed. Eighteen were mono- and 8 were bisegmental fixations for a total of 34 fused segments. Seven patients (26.9%) showed a preoperative sagittal imbalance (defined as SVA>50 mm); 7 patients presented preoperative severe pelvic retroversion (defined as PT>20°) and 1 patient presented both. Disc height, intervertebral angle and segmental lordosis at the operated level significantly increased after surgery (P<0.01). No postoperative significant change in global sagittal alignment (SVA, TPA, T1SPi, T9SPi), pelvic orientation (SS, PT), coronal alignment, lumbar and L4-S1 lordosis and thoracic kyphosis have been observed. Mono- and bisegmental lordosizing fusion techniques, as XLIF and TLIF, are able to restore disc height and improve segmental lordosis. However they do not allow restoration of sagittal balance or improvement of compensatory mechanisms. A limited spinal reconstructive surgery on symptomatic levels can be reasonably proposed to patients with hidden or evident sagittal imbalance with any short-term radiographic impact.

A method of lumbar pedicle screw placement optimization applied to guidance techniques

Pedicle screws are an established method for spinal segmental fixation. To pursue high accuracy and minimally invasive, various different guidance techniques have developed. However, the preoperative screw position plans are determined by manual selection which demands complex operations and costs a lot of time. In addition, the current paths planning only consider the position, without taking the postoperative screws retention into consideration. In order to solve the problems, a new method was proposed to plan the lumbar pedicle screw placement automatically. Firstly, identify pedicle area and establish initial path based on the current vertebrae segmentation technology. After that, optimize path via the improved boundary limited Nelder–Mead simplex algorithm, and get the highest firmness path in theory. We considered that both the accuracy of position and the firmness of postoperative screws, achieved a fully automatic optimal path planning, which can effectively assist operators, improve the firmness of screw placement.

Intermediate screws in short segmental pedicular fixation for thoracolumbar fractures. Retrospective study Of 4 and 6-screw constructs

Introduction Short segment pedicle screw fixation is the most common treatment for thoracolumbar fractures. However, it may not be adequate to achieve and maintain reduction of the fracture and is associated with a high rate of failure. Additional procedures have been offered as alternative solutions to prevent this failure. Long segmental instrumentation or placements of screws at fracture site are some alternatives. Correction of sagittal deformity is important for the maintenance of fracture reduction and may have an effect on functional outcome. Intraoperative correction of sagittal deformity and fracture reduction can be managed easily through placement of screws at the fracture level. Objectives The purpose of this retrospective study was to evaluate the efficacy of screw placement at the fracture level in correction of deformity, maintenance of correction and preventing the failure of fixation in thoracolumbar fractures. Methods Retrospective study of patients with thoracolumbar fractures treated with 4 or 6-screw construct. Preoperative, postoperative and follow-up were evaluated. To evaluate the efficacy of fracture level screw fixation anterior vertebral height compression (%ABC), local kyphosis (KA) and load-sharing classification were compared. %ABC was calculated by using the formula adopted by Mumford et al. Local kyphosis was measured according to Cobb's method. Student t test was used for statistical analysis of variables. A p-value < 0.05 was considered statistically significant. Results The load-sharing classification was similar between the groups. The preoperative KA was statistically similar between groups (P = 0.552). The percentage of KA correction was lowest in the 4-screw construct group (P = 0.034). During follow-up, KA correction was more maintained in 6-screw construct group (P = 0.045). The average preoperative %ABC was similar in groups (P = 0.855). %ABC was more maintained in 6-screw construct group during follow-up. Conclusion Segmental fixation of fractures with screws at the level of fracture offers improved biomechanical stability and provides for additional fixation points that may aid in reduction. The 6-screw construct yields excellent results with a very low rate of failure.

Outcomes Evaluation of Zero-Profile Devices Compared to Stand-Alone PEEK Cages for the Treatment of Three- and Four-Level Cervical Disc Disease

Background: Anterior cervical discectomy and fusion (ACDF) is a well-accepted treatment option for patients with cervical spine disease. Three- and four-level discectomies are known to be associated with a higher complication rate and lower fusion rate than single-level surgery. This study was performed to evaluate and compare zero-profile fixation and stand-alone PEEK cages for three- and four-level ACDF.Methods: Two cohorts of patients who underwent ACDF for the treatment of three- and four-level disease were compared. Thirty-three patients underwent implantation of zero-profile devices that included titanium screw fixation (Group A). Thirty-five patients underwent implantation of stand-alone PEEK cages without any form of screw fixation (Group B).Results: In Group A, twenty-seven patients underwent a three-level and six patients a four-level ACDF, with a total of 105 levels. In Group B, thirty patients underwent a three-level and five patients underwent a four-level ACDF, with a total number of 110 levels. In Group A, the mean preoperative visual analog scale score (VAS) for arm pain was 6.4 (range 3-8), and the mean postoperative VAS for arm pain decreased to 2.5 (range 1-7). In group B, the mean preoperative VAS of arm pain was 7.1 (range 3-10), and the mean postoperative VAS of arm pain decreased to 2 (range 0-4). In Group A, four patients (12%) developed dysphagia, and in Group B, three patients (9%) developed dysphagia. Conclusions: This study found zero-profile instrumentation and PEEK cages to be both safe and effective for patients who underwent three- and four-level ACDF, comparable to reported series using plate devices. Rates of dysphagia for the cohort were much lower than reports using plate devices. Zero-profile segmental fixation devices and PEEK cages may be considered as viable alternatives over plate fixation for patients requiring multi-level anterior cervical fusion surgery.

A Systematic Review With Consensus Expert Opinion of Best Reconstructive Techniques After Osseous En Bloc Spinal Column Tumor Resection.

Systematic literature review and consensus expert opinion. To provide recommendations on reconstructive constructs for large tumor resections of the spinal column. Four questions were studied: (1) What are the best reconstructive options for single versus multilevel resections? (2) Should short segment fixation be considered in primary tumor reconstruction? (3) How should reconstructive techniques differ at various regions of the spine? (4) Does planned postoperative radiation change the fusion strategy? Primary spinal tumors requiring en bloc resection are rare. Most studies focus on disease-free survival and local recurrence rates. Few studies focus on reconstructive options and outcomes with respect to fusion rates and need for revision. A literature search was performed from January 1990 to December 2013. Data were combined and construct survivorship summarized. A survey was administered to international spine tumor surgeons, evaluating reconstructive preferences. The search yielded 381 articles, 12 included in the final analysis. Revision rates for anterior reconstruction were similar for autogenous strut grafts (10%), cages (7.7%), and allograft strut grafts (8.3%). There were two reports of revision from short to long segment constructs and three reports of broken pedicle screws, one requiring revision. Expert survey results revealed that most surgeons preferred cages packed with morcelized allograft and autograft (75%) for anterior reconstruction of single-level vertebrectomies, and strut bone grafting at the cervicothoracic junction (65%) and when more than one vertebrae was resected in the mid-thoracic spine (75%). Surgeons may alter their fusion technique if postoperative radiation is planned. Posterior reconstruction with at least two vertebral levels above and below is recommended. Cages should be used for single-level defects and structural bone graft alone, or in combination with a cage, should be used when spanning a defect greater than two vertebral bodies. Planned postoperative radiation may affect fusion strategy. N/A.

Posterior fixation including the fractured vertebra in short segment fixation of unstable thoracolumbar junction burst fractures

The aim of this study was to evaluate the efficacy of inclusion of the fractured vertebra in short segment fixation in terms of clinical and the radiological outcomes in unstable thoracolumbar junction burst fractures at a minimum of 1 year follow-up. Records of 52 patients (age: 21-50 years) with thoracolumbar burst fracture (T10–L2) in Magerl Type A fractures underwent posterior pedicle screw fixation including the fractured vertebra. Clinical parameters were back pain using Visual Analogue Score (VAS) and disability using Oswestry disability index (ODI), neurological deficit (using ASIA grade) and radiologic parameters (Cobb angle, the kyphotic deformation and vertebral height) were measured before surgery and at 3, 6 and 12 months post-operatively. The presence of screw breakage, screw pullout, peri-implant loosening, and rod breakage were considered as criteria for implant failure. The majority of fractures resulted due to falls (31 cases), and the remaining cases resulted from car accidents (21 cases). The fractured vertebral body level was L1, T12, L2, T11, and T10 in 23, 17, 6, 4 and 2 cases and achieved satisfactory clinical outcomes according to the modified Mcnab criteria 18, 25, 6 and 3 cases were considered to have excellent, good, fair, and poor outcome. The mean kyphotic angle at pre-, post-operative and final follow-up was 13.5 ± 6.3, 13.4 ± 4.3, 8.5 ± 6. The average loss of kyphosis correction was 6.4 ± 5.2° at the final follow-up. The mean pre- and post-operative kyphotic deformation of vertebral body was 5.1 ± 3.2, 4.8 ± 2.3 and at final follow-up was 4.5 ± 4.0 (p&gt;0.05). The mean anterior and posterior vertebral height also showed significant improvements post-operatively, which were maintained at the final follow-up. The mean ODI and VAS scores at the end of 1 year were 17.4%, 1.7 respectively. There was no case of major complication after surgery and during the follow-up period. In conclusion, reduction of unstable thoracolumbar junction burst fracture can be achieved and maintained with the use of short-segment pedicle screw fixation including the fractured vertebra, avoiding the need for anterior reconstruction.

Surgical options for delayed osteoporotic vertebral collapse

To investigate the surgical options and clinical effects of delayed osteoporotic vertebral collapse. From May 2010 to October 2014, 19 patients (20 vertebrae) with delayed osteoporotic vertebral collapse(Kümmell's disease) were enrolled in this study. There were 7 males and 12 females, aged from 65 to 87 years old with a mean of (73.5±5.62) years. According to Li staging system of Kümmell's disease, 3 cases were stage II, 13 cases (14 vertebrae) were stage III without spinal cord injury, 3 cases were stage III with spinal cord injury. Patients were respectively treated with percutaneous vertebroplasty(PVP) or percutaneous kyphoplasty(PKP) on the basis of the degree of postural reduction during operation. Injected cement volume, cement leakage, vertebral height restoration and local kyphotic reduction were observed. Visual analogue scale (VAS) and Oswestry Disability Index(ODI) were respectively used to assess the pain and function before and after operation. Frankel grade were used to evaluate neurological status. Seven vertebrae with satisfactory postural reduction were treated with PVP, 13 vertebrae with unsatisfactory postural reduction were treated with PKP, 3 patients with spinal cord injury were treated with decompression and posterior short segment fixation at the same time. All patients were followed up from 10 to 48 months with an average of 21.2 months. Cement leakage occurred in 4 cases with no symptom, 1 cases in PVP group and 3 cases in PKP group, there was no significant difference between two groups(P=0.561). The priming volume of cement was (6.40±0.94) ml in PVP group and (5.46±1.09) ml in PKP group (P>0.05). Three days after operation vs preoperation, the vertebral height restoration and kyphotic improvement was(31.71±11.35)%, (9.79±4.64)° in PVP group and (24.77±8.51)%, (8.15±2.97)° in PKP. There was no significant difference between two groups(P>0.05). Three days after operation, VAS of low back pain and ODI in all patients were improved than preoperative data(P<0.05), but there was no significant difference between two groups or between postoperative at 3 d and final follow up(P>0.05). Nerve function of 3 patients underwent decompression and fixation from Frankel D to E. According to Li staging system and the degree of introperative postural reduction, individualized surgical treatment for Kümmell's disease can obtain good clinical results. Bad postural reduction during operation maybe a risk factor of cement leakage.

Cost-effectiveness Analysis of Existing Pedicle Screws Reusing Technique in Extension Revision Operation for Adjacent Segmental Stenosis After Lumbar Posterolateral Fusion.

Retrospective case-control study. A cost-effectiveness analysis was performed by comparing patients who received extension revision operations for adjacent segment disease (ASD) reusing the pedicle screws extracted from fused segments with patients who received conventional surgery. ASD often required extension revision surgery, and during extension surgery, pedicle screws may be reused by extracting from the fused segments of primary surgery. Study examined 37 patients who received extension revision surgery for ASD from January 2003 to December 2013. For the fixation of extended segments during revision operation, in 16 cases the pedicle screws extracted from fused segments were reused (group R), and in 21 cases new pedicle screws were used (group C) as a conventional method. Clinical outcomes were evaluated by means of visual analog scale scores for lumbago and leg pain, and the Korean Oswestry Disability Index. Radiologic outcomes were evaluated from the extent of bone union. The total operating costs in the two groups were compared. Visual analog scale scores for lumbago and leg pain, and the Korean Oswestry Disability Index measured at final follow-up averaged 3.6 and 3.8, and 19.9 in group R, and 3.8 and 3.1, and 21.1 in group C, respectively (P = 0.280, P = 0.387, P = 0.751). For radiologic outcomes, there was one case of nonunion in each group. The cost of surgery was 5332 US dollars in group R, and 6109 US dollars in group C, respectively (P = 0.036). Reusing pedicle screws extracted from the fused segments during extension revision operation for ASD can reduce the cost of surgery, and achieves clinical and radiological results similar to those of the conventional operation. 4.

The Effect of Intraoperative Screw Monitoring (Root Monitoring) with the INS-1 System (NUVASIVE) on the Radiological Outcome of Dorsal Instrumentation of the Lumbar Spine

Transpedicular screw fixation of spinal segments has been described for a variety of surgical indications and is a key element in spinal surgery. The aim of transpedicular screw fixation is to achieve maximal stability. Screw malposition should be obviated to avoid neurological complications. There are published methods of applying evoked EMG to control screw position in relation to neural structures. These studies demonstrated that an intact bony pedicle wall acts as an electrical isolator between the screw and spinal nerve root. The aim of our study was to evaluate the impact of intraoperative pedicle screw monitoring on screw positioning. We enrolled 22 patients in this prospective randomised study, who underwent spinal instrumentation after being split into two equal groups. In the first group, dorsal instrumentation was supplemented with intraoperative nerve root monitoring using the INS-1-System (NuVasive, San Diego USA). In the second group, screws were inserted without additional pedicle monitoring. All patients underwent monosegmental instrumentation with "free hand implanted" pedicle screws. 44 screws were inserted in each group. The screw position was evaluated postoperatively using CT scans. The position of the screws in relation to the pedicle was measured in three different planes: sagittal, axial and coronal. The accuracy of the screw position was described using the Berlemann classification system. Screw position is classified in three groups: type 1 correct screw position, type 2 encroachment on the inner cortical wall, type 3 pedicle cortical perforation. Screw angulation and secondary operative criteria were also evaluated. The use of neuromonitoring did not influence the distance between the centre of the screws and the pedicle wall. Distances only depended on the implantation side (right and left) and the height of implantation (caudal or cranial screw). Because of the low number of cases, no conclusion could be reached about the influence of root monitoring on the correct positioning of the screws. There was at least a non-significant trend towards more frequent perforation of the pedicle in the monitor group. In the present study, we showed that root monitoring had a significant effect on the scattering of transversal angles. These were increased compared to the control group. Otherwise, the implantation angle was not shown to depend on the use of neuromonitoring. Neuromonitoring did not influence blood loss or operative time. The data did not permit any conclusion as to whether this technique can minimise the frequency of pedicle screw malposition. The four coronal plane distances did not depend on the use of neuromonitoring. The inclination angle was also unaffected by neuromonitoring. The only parameter for which we found any effect was the transverse angle. The mean values were similar in both groups, but the variances were not equal. The effect of monitoring on the only parameter which could not be evaluated by fluoroscopy is thus rather unfavourable.

The clinical efficacy of pathologic vertebral surgery for thoracic and lumbar tuberculosis

Objective To discuss the clinical efficacy of surgical treatment of pathologic vertebral surgery for thoracic and lumbar tuberculosis. Methods All of 322 cases of thoracic and lumbar spinal tuberculosis patients from December 2003 to June 2014 were retrospectively analyzed in our department. All patients were underwent debridement, fusion and nerve decompression surgery. According to different fixed methods, patients were divided into pathologic vertebral surgery group (fixation completed within lesions invaded motion unit) including 91 males and 100 females, with an average age of 41.53 years, and non-pathologic vertebral surgery group (long segments or short segment fixation) including 61 males and 70 females, with an average age of 42.72 years. We observed the tuberculosis cure rate, degrees of deformity, pain and neurological recovery, operative time, blood loss and complications by follow-up. Results The average follow-up time was 75.52 months in pathologic vertebral surgery group and 76.21 months in non-pathologic vertebral surgery group. The total number of pathologic vertebras in pathologic vertebral surgery group and non-pathologic vertebral surgery group were 277 and 218 respectively, and the average was 1.45 and 1.66. The total number of fixed segments was 277 in pathologic vertebral surgery group and 485 in non-pathologic vertebral surgery group, and the average fixed segments was 1.45 and 3.70. The cure rate was 85.86% in pathologic vertebral surgery group and 85.49% in non-pathologic vertebral surgery group at 6 months postoperatively, and 98.95% and 98.47% at the last follow-up time, with no significant difference between groups. Graft fusion rate was 89.00% in pathologic vertebral surgery group and 89.31% in non-pathologic vertebral surgery group 6 months postoperatively, 98.38% and 98.47% at the last follow-up time, without significant difference. In lumbar spine, the average correction of Cobb's angle was 12.4° in pathologic vertebral surgery group and 13.1° in non-pathologic vertebral surgery group, and the average angle loss was 1.3 and 1.4°, with no significant difference. In thoracolumbar, the average correction of Cobb's angle was 10.9°in pathologic vertebral surgery group and 11.1°in non-pathologic vertebral surgery group, and the average angle loss was 1.7°and 1.5° respectively, without significant difference. However, in thoracic, the average correction of Cobb's angle was 10.2° in pathologic vertebral surgery group and 12.7° in non-pathologic vertebral surgery group, and the average angle loss was 3.6° and 2.5°respectively, with significant difference. The mean operation time was 210.45 min in pathologic vertebral surgery group and 210.45 min in non-pathologic vertebral surgery group, with significant difference. The average blood loss was 726.12 ml in pathologic vertebral surgery group and 726.12 ml in non-pathologic vertebral surgery group, with significant difference. The complication rate was 11.51% in pathologic vertebral surgery group and 11.45% in non-pathologic vertebral surgery group, with no significant difference. Conclusion Pathologic vertebral surgery surgery is a safe, effective and feasible method of operation for treatment of thoracic and lumbar tuberculosis, which can effectively preserve adjacent normal vertebral motion unit features. The thoracic surgery was less satisfactory than the lumbar and thoracolumbar surgery. Key words: Thoracic vertebrae; Lumbar vertebrae; Tuberculosis, spinal; Bone transplantation; Treatment outcome

Surgical safety of cervical pedicle screw placement with computer navigation system

Cervical pedicle screw (CPS) may be the biomechanically best system for posterior cervical segmental fixation, but may carry a surgery-related risk. The purpose of this study was to evaluate the safety of CPS placement using computer navigation system for posterior cervical instrumented fixation and discuss its complication avoidance and management. Posterior cervical instrumented fixation using CPS was performed in a total of 128 patients during the period between 2007 and 2015. Intraoperative image guidance was achieved using a preoperative 3D CT-based or an intraoperative 3D CT-based navigation system. A total of 762 CPSs were placed in the spine level of C2 to Th3. The radiological accuracy of CPS placement was evaluated using postoperative CT. Accuracy of CPS placement using a preoperative 3D CT-based navigation system was 93.6 % (423 of 452 screws) in grade 0; the screw was completely contained in the pedicle, and accuracy of CPS placement using an intraoperative 3D CT-based navigation system was a little bit improved to 97.1 % (301 of 310 screws) in grade 0. CPS misplacement (more than half of screw) was 3.3 % (15 of 452 screws) using a preoperative 3D CT-based navigation system, and CPS misplacement (more than half of screw) was 0.6 % (2 of 310 screws) using an intraoperative 3D CT-based navigation system. In total, 38 screws (5.0 %) were found to perforate the cortex of pedicle, although any neural or vascular complications closely associated with CPS placement were not encountered. Twenty nine of 38 screws (76.3 %) were found to perforate laterally, and seven screws (18.4 %) were found to perforate medially. Image-guided CPS placement has been an important advancement to secure the safe surgery, although the use of CPS placement needs to be carefully determined based on the individual pathology.

Fixed-Angle, Posteriorly Connected Anterior Cage Reconstruction Improves Stiffness and Decreases Cancellous Subsidence in a Spondylectomy Model.

An idealized biomechanical model. The aim of this study was to evaluate the biomechanical properties of a construct designed to minimize intervertebral cage subsidence and maximize stiffness. Reconstruction after vertebral resection typically involves posterior segmental fixation and anterior interbody support. However, poor bone density, adjuvant radiation, or the oncologic need for endplate resection make interbody device subsidence and resultant instrumentation failure a significant concern. An idealized thoracolumbar spondylectomy reconstruction model was constructed using titanium segmental instrumentation and Delrin plastic. In vivo mechanical stress was simulated on a custom multi-axis spine simulator. Rigid body position in space was measured using an optical motion-capture system. Cancellous subsidence was modeled using a 1 cm thick wafer of number 3 closed-cell Sawbones foam at one endplate. Ten foam specimens were tested in a control state consisting of posterior segmental fixation with a free interbody cage. Ten additional foam specimens were tested in the test state, with the Delrin interbody cage "connected" to the posterior rods using two additional pedicle screws placed into the cage. Foam indentation was quantified using a precision digital surface-mapping device, and subsidence volume calculated using geometric integration. The control group exhibited significantly greater foam indentation after cycling, with a mean subsidence volume of 1906 mm [95% confidence interval (95% CI) 1810-2001] than the connected cage group subsidence volume of 977 mm (95% CI 928-1026 mm; P < 0.001]. Construct stiffness was greater in the connected cage group (3.1 Nm/degree, 95% CI 3.1-3.2) than in the control group (2.3 Nm/degree, 95% CI 2.2-2.4; P < 0.001). In an idealized spondylectomy model, connecting the anterior column cage to the posterior instrumentation using additional pedicle screws results in a construct that is nearly 40% stiffer and exhibits 50% less cancellous subsidence compared with a traditional unconnected cage. N/A.

Surgical Results of 135 Thoraco-Lumbar Fractures Treated with Open Posterior Multi-Level Segmental Fixation: A Single Center Experience

Introduction Surgical treatment strategies for thoraco-lumbar spine fractures differ widely around the world. Choice of operative approach varies depending on many factors including fracture classification, presence of spinal cord injury and whether subluxation or dislocation is present. Combinations of anterior and posterior approaches vary depending on surgeon choice, available resources and fracture morphology. We reviewed our experience of thoraco-lumbar vertebral fractures treated at our institution from Jan 14 – May 2015 to determine if our policy of posterior multi- level segmental fixation produced acceptable restoration of spinal alignment and reduction of kyphosis. Materials and Methods A retrospective cohort review was performed using the hospital electronic medical records system (Cerner, USA). All surgical cases were identified from the operating theater records. Only fractures from T1 to L5 were included. Imaging was reviewed using the hospital PACS system and classified according to the AO thoraco -lumbar classification system. Spinal cord injury was classified according to the ASIA scale. Post-operative images were reviewed and levels of fixation recorded. Accuracy of screw placement was assessed. Neurological status at discharge was recorded. Results 135 cases of TL fracture underwent surgery via an open posterior approach. Screw placement was performed using C-arm fluoroscopy.Data on the extent of kyphosis reduction is presented. Post-operative results in cases of vertebral subluxation and dislocation are presented. Early surgical outcome in cases with spinal cord injury are presented. Due to the high level of loss to follow up in our region we were unable to carry out longitudinal outcome studies. Conclusion The majority of thoraco -lumbar fractures can be managed by posterior approaches alone with good surgical outcomes. Type C fractures and fractures with dural tears and nerve damage can be adequately dealt with via this approach. The majority of cases had pedicle screw fixation two levels above and one level below the affected level. This strategy allowed good reduction of deformity, especially for fractures at L1, where fixation only to T12 can be associated with late onset of adjacent segment degeneration.The inability to carry out longitudinal outcome measures is an acknowledged weakness of our study, but the short-term surgical results are comparable to those in the literature using other surgical strategies. This retrospective cohort review supports our continuing use of the posterior multi-level segmental approach for T-L fractures irrespective of fracture type.