Comparative analysis of pedicle screw and hook instrumentation in posterior correction and fusion of idiopathic thoracic scoliosis

Posterior correction and fusion with segmental hook instrumentation represent the gold standard in the surgical treatment of progressive idiopathic thoracic scoliosis. However, there is a debate over whether pedicle screws are safe in scoliosis surgery and whether their usage might enable a better curve correction and a shorter fusion length. The details of curve correction, fusion length and complication rate of 99 patients with idiopathic thoracic scoliosis treated with either hook or pedicle screw instrumentation were analyzed. Forty-nine patients had been operated with the Cotrel-Dubousset system using hooks exclusively ("hook group"). Fifty patients had been operated with either a combination of pedicle screws in the lumbar and lower thoracic and hooks in the upper thoracic spine or exclusive pedicle screw instrumentation using the Münster Posterior Double Rod System ("screw group"). The preoperative Cobb angle averaged 61.3 degrees (range 40 degrees-84 degrees ) in the hook group and 62.5 degrees (range 43 degrees-94 degrees ) in the screw group. Average primary curve correction was 51.7% in the hook group and 55.8% in the screw group ( P>0.05). However, at follow-up (2-12 years later) primary curve correction was significantly greater ( P=0.001) in the screw group (at 50.1%) compared to the hook group (at 41.1%). Secondary lumbar curve correction was significantly greater ( P=0.04) in the screw group (54.9%) compared to the hook group (46.9%). Correction of the apical vertebral rotation according to Perdriolle was minimal in both groups. Apical vertebral translation was corrected by 42.0% in the hook group and 55.6% in the screw group ( P=0.008). Correction of the tilt of the lowest instrumented vertebra averaged 48.1% in the hook group and 66.2% in the screw group ( P=0.0004). There were no differences concerning correction of the sagittal plane deformity between the two groups. Fusion length was, on average, 0.6 segments shorter in the screw group compared to the hook group ( P=0.03). With pedicle screws, the lowest instrumented vertebra was usually one below the lower end vertebra, whereas in the hook group it was between one and two vertebrae below the lower end vertebra. Both operative time and intraoperative blood loss were significantly higher in the hook group ( P<0.0001). One pedicle screw at T5 was exchanged due to the direct proximity to the aorta. There were no neurologic complications related to pedicle screw instrumentation. Pedicle screw instrumentation alone or in combination with proximal hook instrumentation offers a significantly better primary and secondary curve correction in idiopathic thoracic scoliosis and enables a significantly shorter fusion length.     

A biomechanical analysis of the self-retaining pedicle hook device in posterior spinal fixation

Regular hooks lack initial fixation to the spine during spinal deformity surgery. This runs the risk of posterior hook dislodgement during manipulation and correction of the spinal deformity, that may lead to loss of correction, hook migration, and post-operative junctional kyphosis. To prevent hook dislodgement during surgery, a self-retaining pedicle hook device (SPHD) is available that is made up of two counter-positioned hooks forming a monoblock posterior claw device. The initial segmental posterior fixation strength of a SPHD, however, is unknown. A biomechanical pull-out study of posterior segmental spinal fixation in a cadaver vertebral model was designed to investigate the axial pull-out strength for a SPHD, and compared to the pull-out strength of a pedicle screw. Ten porcine lumbar vertebral bodies were instrumented in pairs with two different instrumentation constructs after measuring the bone mineral density of each individual vertebra. The instrumentation constructs were extracted employing a material testing system using axial forces. The maximum pull-out forces were recorded at the time of the construct failure. Failure of the SPHD appeared in rotation and lateral displacement, without fracturing of the posterior structures. The average pull-out strength of the SPHD was 236 N versus 1,047 N in the pedicle screws (P < 0.001). The pull-out strength of the pedicle screws showed greater correlation with the BMC compared to the SPHD (P < 0.005). The SPHD showed to provide a significant inferior segmental fixation to the posterior spine in comparison to pedicle screw fixation. Despite the beneficial characteristics of the monoblock claw construct in a SPHD, that decreases the risk of posterior hook dislodgement during surgery compared to regular hooks, the SPHD does not improve the pull-out strength in such a way that it may provide a biomechanically solid alternative to pedicle screw fixation in the posterior spine.     

Correlative analysis of the results of surgical treatment of thoracolumbar injuries with long Texas Scottish rite hospital construct: is the use of pedicle screws versus hooks advantageous in the lumbar spine?

This is a prospective, randomized study to compare the efficacy of two similar "long-segment" Texas Scottish Rite Hospital instrumentations with the use of hooks in the thoracic spine and pedicle screws versus laminar hook claw in the lumbar spine for thoracolumbar A3, B, and C injuries. Forty consecutive patients with such thoracolumbar fractures (T11-L1) associated with spinal canal encroachment underwent early operative postural reduction and stabilization. The patients were randomly sampled into two groups: Twenty patients received hooks in "claw configuration" in both the thoracic and the lumbar spine (group A), and 20 patients received hooks in the thoracic vertebrae and pedicle screws in the lumbar vertebrae (group B). Pre- and postoperative plain roentgenograms and computed tomography scans were used to evaluate any changes in Gardner post-traumatic kyphotic deformity, anterior and posterior vertebral body height at the fracture level, and spinal canal clearance (SCC). All patients were followed for an average period of 52 months (range 42-71 months). The correction of anterior vertebral body height was significantly more (P < 0.01) in the spines of group B (33%) than in group A (16%), with a subsequent 11% loss of correction at the latest evaluation in group A and no loss of correction in group B. There were no significant differences in the changes of posterior vertebral body height and Gardner angle between the two groups. The SCC was significantly more (P < 0.05) immediately postoperatively in the spine of group B (32%) than in group A (19%). In the latest evaluation, there was a 9% loss of the immediately postoperatively achieved SCC in group A, while SCC was furthermore increased at 10.5% in group B. All patients with incomplete neurologic lesions in groups A and B were postoperatively improved at 1.1 and 1.7 levels, respectively. There were two hook dislodgements in the thoracic spine, one in each group, while there was no screw failure in group B. There was neither pseudarthrosis nor neurologic deterioration following surgery. Visual Analog Pain Scale and Short Form-36 scores were equally improved and did not differ between the two groups. The use of pedicle screws in the lumbar spine to stabilize the lowermost end of a long rigid construct applied for A3, B, and C thoracolumbar injuries was advantageous when compared with that using hook claws in the lumbar spine because the constructs with screws restored and maintained the fractured anterior vertebral body height better than the hooks without subsequent loss of correction and safeguarded postoperatively a continuous SCC at the injury level.     

椎板钩和椎弓根钉系统治疗脊柱侧凸病例对照研究

目的 探讨脊柱椎弓根钉系统治疗脊柱侧凸是否安全．是否可以矫正出更好的曲线，是否能达到更短节段的融合。方法 50例特发性脊柱侧凸患者中15例采用椎板钩系统手术(椎板钩组)，25例采用上胸段椎板钩、下胸段和腰段椎弓根钉联合术式或者完全川椎弓根钉系统手术(椎弓根钉组)比较两组矫正曲线、融合长度以及并发症发生率。结果 随访1～8年，曲线校正：椎弓根钉组达50．1％，明显好于椎板钩组的41.1％。矢状面畸形的矫正：两组没有区别融合长度：椎弓根钉组较椎板钩组平均少0．6个锥体。结论 椎弓根钉组在矫正侧凸的角度等方面明显好于椎板钩组。     

Dorsale operative Korrektur der idiopathischen Skoliose

Posterior correction and fusion of scoliosis with multisegmental instrumentation systems was developed by Cotrel-Dubousset in the 1980s. Initially correction and instrumentation was performed using hooks only. Later pedicle screws were implemented first for the lumbar and then for the thoracic spine. Nowadays instrumentation based on pedicle screws only is well established for posterior scoliosis surgery. Biomechanical studies demonstrated higher pull-out forces for pedicle than for hook constructs. In clinical studies several authors reported better Cobb angle correction of the primary and the secondary curves and less loss of correction in pedicle screw versus hook instrumentations. Furthermore, pedicle screw instrumentation allows fewer segments to be fused, especially caudally, and thus saving mobile segments. In most of these publications there were no differences in operation time, blood loss and complication rates. In summary, there is better curve correction without an increased risk using multisegmental pedicle screw instrumentation in modern posterior scoliosis surgery.     

CT薄层扫描枢椎椎动脉孔术前评估方法的临床应用

目的探讨螺旋CT薄层扫描枢椎椎动脉孔解剖变异术前评估在个体化置钉中的应用价值。方法 80例寰枢椎手术患者共160个枢椎椎弓根,术前接受薄层CT扫描,根据参数（a椎动脉入口与椎管外壁的距离）和参数（e椎动脉球顶部顶点与侧块上关节面的距离）将枢椎椎弓根分为4种类型,Ⅰ/Ⅲ/Ⅳ型选择椎弓根固定,Ⅱ型选择椎板螺钉或椎板钩固定。术后病例行CT钉道扫描复查。结果Ⅰ型椎弓根102个,Ⅱ型26个,Ⅲ型21个,Ⅳ型11个。134个Ⅰ/Ⅲ/Ⅳ型椎弓根实施椎弓根螺钉内固定,26个Ⅱ型椎弓根被判定不适于进行椎弓根螺钉固定,改用椎板螺钉（15枚）固定和椎板钩（11枚）固定。术后CT钉道扫描复查显示,130侧次椎弓根螺钉位置良好,4侧次偏外穿入椎动脉孔,但未造成严重后果。结论术前应用螺旋CT薄层扫描枢椎椎动脉孔技术可以有效判读枢椎椎弓根类型,确定合理的手术方式,从而提高椎弓根固定的成功率,降低手术风险。     

Biomechanical evaluation of a new fixation device for the thoracic spine

The technology used in surgery for spinal deformity has progressed rapidly in recent years. Commonly used fixation techniques may include monofilament wires, sublaminar wires and cables, and pedicle screws. Unfortunately, neurological complications can occur with all of these, compromising the patients’ health and quality of life. Recently, an alternative fixation technique using a metal clamp and polyester belt was developed to replace hooks and sublaminar wiring in scoliosis surgery. The goal of this study was to compare the pull-out strength of this new construct with sublaminar wiring, laminar hooks and pedicle screws. Forty thoracic vertebrae from five fresh frozen human thoracic spines (T5–12) were divided into five groups (8 per group), such that BMD values, pedicle diameter, and vertebral levels were equally distributed. They were then potted in polymethylmethacrylate and anchored with metal screws and polyethylene bands. One of five fixation methods was applied to the right side of the vertebra in each group: Pedicle screw, sublaminar belt with clamp, figure-8 belt with clamp, sublaminar wire, or laminar hook. Pull-out strength was then assessed using a custom jig in a servohydraulic tester. The mean failure load of the pedicle screw group was significantly larger than that of the figure-8 clamp (P = 0.001), sublaminar belt (0.0172), and sublaminar wire groups (P = 0.04) with no significant difference in pull-out strength between the latter three constructs. The most common mode of failure was the fracture of the pedicle. BMD was significantly correlated with failure load only in the figure-8 clamp and pedicle screw constructs. Only the pedicle screw had a statistically significant higher failure load than the sublaminar clamp. The sublaminar method of applying the belt and clamp device was superior to the figure-8 method. The sublaminar belt and clamp construct compared favorably to the traditional methods of sublaminar wires and laminar hooks, and should be considered as an alternative fixation device in the thoracic spine.     

全椎弓根螺钉与钩钉联合系统对脊柱侧凸的矫形效果比较

目的比较全椎弓根螺钉与钩钉联合系统对特发性脊柱侧凸的后路矫形效果。方法对40例特发性脊柱侧凸患者进行回顾性对照研究,其中全节段椎弓根螺钉组20例,钩钉联合器械组20例。对两组的手术效果、手术时间和失血量等进行对照分析。结果平均冠状面矫形率：全节段椎弓根螺钉组82．4％,钩钉联合器械组71．8％（P〈0．01）;术后1—3年平均冠状面矫形率：全节段椎弓根螺钉组77．O％,钩钉联合器械组62．5％（P〈0．01）;平均顶椎旋转矫正率：全节段椎弓根螺钉组63％,钩钉联合器械组32％（P〈0．01）。而矢状面矫形效果、下固定椎倾斜度改善率、躯干偏移、手术时间、失血量方面,两组无明显差别（P〉0．05）。所有病例均未出现脊髓、神经根损伤等严重并发症。结论全椎弓根螺钉较钩钉联合系统具有更好的矫形效果,胸椎椎弓根螺钉置入安全可靠。     

New means in spinal pedicle hook fixation

Summary Pedicle hooks which are used as an anchorage for posterior spinal instrumentation may be subjected to considerable three-dimensional forces. In order to achieve stronger attachment to the implantation site, hooks using screws for additional fixation have been developed. The failure loads and mechanisms of three such devices have been experimentally determined on human thoracic vertebrae: the Universal Spine System (USS) pedicle hook with one screw, a prototype pedicle hook with two screws and the Cotrel-Dubousset (CD) pedicle hook with screw. The USS hooks use 3.2-mm self-tapping fixation screws which pass into the pedicle, whereas the CD hook is stabilised with a 3-mm set screw pressing against the superior part of the facet joint. A clinically established 5-mm pedicle screw was tested for comparison. A matched pair experimental design was implemented to evauluate these implants in constrained (series I) and rotationally unconstrained (series II) posterior pull-out tests. In the constrained tests the pedicle screw was the strongest implant, with an average pull-out force of 1650 N (SD 623 N). The prototype hook was comparable, with an average failure load of 1530 N (SD 414 N). The average pull-out force of the USS hook with one screw was 910 N (SD 243 N), not significantly different to the CD hook's average failure load of 740 N (SD 189 N). The result of the unconstrained tests were similar, with the prototype hook being the strongest device (average 1617 N, SD 652 N). However, in this series the difference in failure load between the USS hook with one screw and the CD hook was significant. Average failure loads of 792 N (SD 184 N) for the USS hook and 464 N (SD 279 N) for the CD hook were measured. A pedicular fracture in the plane of the fixation screw was the most common failure mode for USS hooks. The hooks usually did not move from their site of implantation, suggesting that they may be well-suited for the socalled segmental spinal correction technique as used in scoliosis surgery. In contrast, the CD hook disengaged by translating caudally from its site of implantation in all cases, suggesting a mechanical instability. The differences in observed hook failure modes may be a function of the type and number of additional fixation screws used. These results suggest that additional screw fixation allows stable attachment of pedicle hooks to their implantation site. Hooks using additional fixation screws passing obliquely into the pedicle apparently provide the most rigid attachment. The second fixation screw of the prototype hook almost doubles the fixation strength. Thus, the prototype hook might be considered as an alternative to the pepdicle screw, especially in the upper thoracic region.     

The USS pedicle hook system: a morphometric analysis of its safety in the thoracic spine. Universal Spine System.

The Universal Spine System (USS) pedicle hook design includes a fixation screw that passes obliquely in the anterocranial direction in the pedicle. The addition of the fixation screw was to address concerns with rotation of the hook and hook disengagement. This study was designed to evaluate the safety of the USS screw locked pedicle hook. Eleven cadaveric thoracic spines were instrumented posteriorly with USS pedicle hooks from T1 to T12. Spinal instrumentation was performed by a spinal surgeon experienced with the USS system. Spinal deformity was created prior to instrumentation, ranging from 0 to 55 degrees in the horizontal plane (rotation) and from 0 to 50 degrees in the frontal plane (scoliosis). Radiographs, computed tomography (CT), and segmental dissection were used for data acquisition. Morphometric CT analysis before instrumentation demonstrated that the transverse pedicular diameter was the smallest at T5 with a mean of 3.7 mm. The transverse pedicular angle (TPA) was found to always point toward the midline. The largest TPA was observed at T1 with a mean TPA of 28.4 degrees. The pedicle with the least angular deviation from the midline was T11 with a mean TPA of 7 degrees. Postinstrumentation CT analysis and segmental dissection revealed perforations of the pedicle cortex by the fixation screw in 15% of instrumented pedicles (26/172). There were 6 medial and 20 lateral perforations. Medial perforations occurred exclusively in the three most proximal spinal segments, whereas the lateral perforations occurred throughout the thoracic spine. The mean encroachment of the fixation screw was 1.67 mm medially and 1.95 mm laterally. This study demonstrates the variation in caliber and direction of the thoracic pedicles. Medial and lateral perforations of the pedicle can occur with the USS pedicle hook instrumented system.     

Comparison of 5-year outcomes between pedicle screw and hybrid constructs in adolescent idiopathic scoliosis

Object Pedicle screw fixation has been theorized to provide better correction of scoliotic deformity, but controversy over the benefits of pedicle screw-only constructs remains, and the longer-term impact of pedicle screw fixation as compared with hybrid constructs is unclear. In this study, a retrospective review of a prospectively collected database was conducted to determine the longer-term impact of pedicle screw fixation as compared with hybrid constructs in patients with adolescent idiopathic scoliosis (AIS). Methods The authors retrospectively reviewed a multicenter database of pediatric patients (ages ≤ 18) from 1995 to 2006 and identified 127 patients with Lenke Type 1-4 AIS curves with a minimum 5 years of follow-up. Patients were divided into 2 cohorts based on whether they had undergone pedicle screw fixation or fixation with hybrid constructs. Results The mean main thoracic curvature of 56.1° ± 13.0°, which corrected to 14.9° ± 9.3°, translated into a mean correction of 73% (p < 0.01). The curve was 19.4° ± 10.6° at 2-year follow-up and 20.5° ± 10.4° at 5 years. When comparing preoperative parameters between the groups, differences were noted in the magnitude of the main thoracic curve (p = 0.04), flexibility of the main thoracic curve (p = 0.02), coronal balance (p = 0.04), T2-12 kyphosis (p = 0.02), and sex (p = 0.02). The pedicle screw cohort had fewer spinal segments instrumented (p < 0.01), fewer anterior releases performed (p = 0.02), and fewer thoracoplasties performed (p < 0.01). By 5 years of follow-up, significant differences were apparent between the two cohorts with respect to upper thoracic curvature (p = 0.01), T2-12 (p = 0.02) and T5-12 (p = 0.02) kyphosis, lumbar lordosis (p < 0.01), and sagittal balance (p = 0.01). Conclusions Although some preoperative differences did exist, outcomes were comparable between hybrid and screw constructs at 2 and 5 years. However, hybrid constructs required more concurrent anterior releases and thoracoplasties to achieve similar results.     

经皮微创椎根弓螺钉内固定治疗胸腰椎压缩性骨折

【摘要】〓目的〓探讨经皮微创行椎弓根螺钉内固定治疗单纯胸腰椎压缩性骨折的临床疗效。方法〓选择2012年1月至2014年11月间我院收治的30例单纯胸腰椎压缩性骨折患者,分为对照组(n=15)和观察组(n=15)。对照组患者采用传统的以伤椎为中心的后正中纵行切口开放手术,观察组患者采用经皮微创椎弓根螺钉内固定手术。比较两组患者手术相关指标、术后48 h疼痛视觉模拟评分(VAS)、手术即期效果和远期效果、术后腰椎手术失败综合征(FBSS)的发生情况。结果〓观察组平均手术时间缩短,术中出血量明显减少,住院时间显著缩短(P<0.05);观察组术后48 h VAS也明显低于对照组为(P<0.05);两组患者术后局部Cobb角矫正率和末次随访局部Cobb角矫正率相似,说明两种手术方式的即期和远期效果相似。对照组患者术后FBSS发生率略高于观察组,但差异无统计学意义。结论〓微创手术创伤小,恢复快,不影响手术的矫正效果。     

Pullout strength of pedicle screws versus pedicle and laminar hooks in the thoracic spine

While the biomechanical properties of pedicle screws have proven to be superior in the lumbar spine, little is known concerning pullout strength of pedicle screws in comparison to hooks in the thoracic spine. In vitro biomechanical pullout testing was performed to evaluate the axial pullout strength of pedicle screws versus pedicle and laminar hooks in the thoracic spine with regard to surgical correction techniques in scoliosis. Nine human cadaveric thoracic spines were harvested and disarticulated. To simulate a typical posterior segmental scoliosis instrumentation, standard pedicle hooks were used between T4 and T8 and supralaminar hooks between T9 and T12 and tested against pedicle screws. The pedicle screws were loaded strictly longitudinal to their axis; the hooks were loaded perpendicular to the intended rod direction. In total, 90 pullout tests were performed. Average pullout strength of the pedicle screws was significantly higher than in the hook group (T4-T8: 531 N versus 321 N, T9-T12: 807 N versus 600 N, p < 0.05). Both screw diameter and the bone mineral density (BMD) had significant influence on the pullout strength in the screw group. For scoliosis correction, pedicle screws might be beneficial, especially for rigid thoracic curves, since they are significantly more resistant to axial pullout than both pedicle and laminar hooks.     

Restoration of thoracic kyphosis in the hypokyphotic spine: a comparison between multiple-hook and segmental pedicle screw fixation in adolescent idiopathic scoliosis

This study verified the efficacy of segmental pedicle screw fixation in restoring thoracic kyphosis in persons with hypokyphotic scoliosis. Fifty-one patients were divided into three groups by the degree of preoperative thoracic hypokyphosis and fixation method used: the hypokyphosis-hook (HH), hypokyphosis-screw (HS), and normal kyphosis-screw (NS) group. They were compared after a minimum follow-up period of 2 years. Preoperative thoracic kyphosis of 4.1 degrees +/- 8.6 degrees, 8.1 degrees +/- 5.6 degrees and 27.3 degrees +/- 9.8 degrees in the HH, HS, and NS groups were restored to 14.5 degrees +/- 10.2 degrees, 27.3 degrees +/- 11.3 degrees, and 28.3 degrees +/- 13.7 degrees, respectively. The difference between the HH and HS groups was significant (p = 0.000). The HS and the NS groups did not differ (p = 0.16). This indicates that segmental pedicle screw fixation was more effective than multiple hooks in restoring kyphosis in patients with hypokyphotic scoliosis and created kyphosis similar to that in patients without preoperative hypokyphosis.     

Percutaneous pedicle screw fixation through the pedicle of fractured vertebra in the treatment of type A thoracolumbar fractures using Sextant system: an analysis of 38 cases

Objective： To prospectively evaluate the feasibility, safety and efficacy of the percutaneous pedicle screw fixation through the pedicle of fractured vertebra in the treatment of type A thoracolumbar fractures using Sextant system in the retrospective non-randomized case-control study. Methods： Atotal of 38 consecutive non-randomized patients with type A thoracolumbar fractures, which had been stabilized posteriorly from December 2006 to March 2009, were examined retrospectively more than 9 months after surgery. Twenty-one patients had been treated conventionally with open pedicle screw fixation （OPSF） and 17 patients received minimally invasive treatment with Sextant percutaneous pedicle screw fixation （SPPSF）. As a method of evaluation, the incision size, the intraoperation and post- operative volume of blood loss, operation time, postoperative hospital stay, blood transfusion, the radiological assessment of the sagittal Cobb＇s angle, vertebral body angle and vertebral body height were recorded and compared. Results： All patients were followed up for 8-24 months （average 11.6 months）. There were significant differences in the incision size, surgical blood loss, surgical draining Joss, operation time, hospital stay after operation, blood transfusion, the proportion of antalgic supplement and postoperative incisional VAS between the two groups （P〈0.05）. Mean preoperative kyphotic deformity was 16.0° and improved by 9.3° after surgery in OPSF group, but 15.2° and 10.3° respectively in SPPSF group. Mean preoperative angle of the fractured vertebral body was 15.9°and improved by 7.9° after surgery in OPSF group, but 14.9° and 6.6° respectively in SPPSF group. Mean anterior vertebral body height （% of normal） was 67.3% before surgery and 95.8% after surgery, but 69.1% and 90.1% respectively in SPPSF group. Mean posterior vertebral body height （% of normal） was 93.3% before surgery and 99.5% after surgery, but 88.9% and 93.3% respectively in SPPSF group. Among the patients whose 9-month follow-up films were available, 3.0° ofkyphosis correction was lost in OPSF group, but 3.2° in SPPSF group. And 1.0°of the angle of the fractured vertebral body correction was lost in OPSF group, but 1.5°in SPPSF group. Then 3.0% of the anterior vertebral body height correction was lost in OPSF group, but 2.2% in SPPSF group. And 3.0% of the posterior vertebral body height correction was lost in OPSF group, but 2.5% in SPPSF group. The sagittal Cobb＇s angle, vertebral body angle and anterior height of the fractured vertebra were all significantly different in each group before and after operation （P〈0.05）. There were no significant differences in the postoperative sagittal Cobb＇s angle, vertebral body angle and the improvement of the vertebral body height and the kyphotic deformity correction between OPSF and SPPSF groups （P〉0.05）, but there was significant difference in the postoperative anterior height of the fractured vertebra between the two groups （P〈0.05）. Conclusion： The percutaneous pedicle screw fixation through the pedicle of fractured vertebra using Sextant system is a good minimally-invasive surgical therapeutic choice for patients with type A thoracolumbar fracture except for that the SPPSF has a little insufficiency in resuming the anterior height of the fractured vertebra compared with OPSF.     

Pedicle morphology in thoracic adolescent idiopathic scoliosis: is pedicle fixation an anatomically viable technique?

STUDY DESIGN: A radiographic study of thoracic pedicle anatomy in a group of adolescent idiopathic scoliosis (AIS) patients. OBJECTIVE: To investigate the anatomic constraints of the thoracic pedicles and determine whether the local anatomy would routinely allow pedicle screw insertion at every level. SUMMARY OF BACKGROUND DATA: In spite of the clinical successes reported with limited thoracic pedicle screw-rod constructs for thoracic AIS, controversy exists as to the safety of this technique. MATERIAL AND METHODS: Twenty-nine patients with right thoracic AIS underwent preoperative thoracic CT scans and plain radiographs. Anatomic parameters were measured from T1 to T12. RESULTS: Information on 512 pedicles was obtained. The transverse width of the pedicles from T1 through T12 ranged from 4.6-8.25 mm. The medial pedicle to lateral rib wall transverse width from T1 through T2 ranged from 12.6 to 17.9 mm. Measured dimensions from the CT scans showed the actual pedicle width to be 1-2 mm larger than would have been predicted from the plain radiographs. Age, Risser grade, curve magnitude, and the amount of segmental axial rotation did not correlate with the morphology or size of the thoracic pedicles investigated. In no case would pedicle morphology have precluded the passage of a pedicle screw. CONCLUSION: Based on the data identified in this group of adolescent patients, it is reasonable to consider pedicle screw insertion at most levels and pedicle-rib fixation at all levels of the thoracic spine during the treatment of thoracic AIS.     

一期经后路三柱重建技术治疗胸腰椎爆裂骨折

目的 探讨严重胸腰椎爆裂骨折应用经后路进行脊柱三柱重建技术的临床效果.方法 对24例胸腰椎爆裂骨折采用经后路椎体次全切除、钛网置入及椎弓根钉重建术治疗.采用Frankel评定标准评定术后神经功能恢复情况.通过影像学变化评价后凸畸形矫正情况和椎管减压程度.结果 本组获随访13～46个月,平均24个月.椎体高度术后恢复至正常高度的97.8％.椎体后凸畸形角度矫正至术后3.5°.椎管容积矫正至术后椎管压迫完全解除.所有患者神经症状均有不同程度恢复.结论 经后路进行脊柱三柱重建技术,能有效矫正胸腰椎爆裂骨折的后凸畸形、解除椎管内压迫,达到术后即刻稳定,具有骨折复位满意,手术创伤较小及并发症少等特点.     

支点弯曲位X线片在辅助青少年脊柱侧凸柔韧性评估中的作用

目的评估支点弯曲位X线片在特发性脊柱侧凸近端胸弯（proximal thoracic,PT）,主胸弯（main thoracic,MT）和胸腰弯/腰弯（thoracolumbar/lumbar,TL/L）冠状位矫形中的作用。方法本研究包括38例连续的行单纯后路椎弓根螺钉矫形固定融合术的青少年脊柱侧凸患者。影像学评估包括术前站立前后位X线片、支点弯曲位X线片,仰卧侧曲位X线片以及术后站立前后位及侧位X线片。测量患者的Cobb角并计算支点弯曲影像（fulcrum bendingradiograph,FBR）柔韧性及支点弯曲矫正指数（fulcrum bending correction index,FBCI）。术后影像学资料包括术后即刻（1周）、3个月、6个月、12个月以及2年随访时的X线片。结果本研究手术节段包括9例PT,37例MT,9例TL/L。平均手术年龄为15.1岁。术前PT组、MT组和TL/L组的FBR柔韧性分别为42.6%、61.1%和66.2%;而平均手术矫正率分别为43.4%、69.3%和73.9%;平均FBCI分别为103.8%、117.0%和114.8%。FBR柔韧性正相关于手术矫正率。尽管MT组和TL/L组的手术矫正率高于PT组,3组的FBCI差异无统计学意义（P〈0.05）。结论支点弯曲位X线片可以用来辅助青少年脊柱侧凸患者的柔韧性评估。采用支点弯曲位X线片对侧凸的柔韧性加以评估后发现,椎弓根螺钉对PT、MT和TL/L的矫形能力是相同的。     

Determination of optimal screw number based on correction angle for main thoracic curve in adolescent idiopathic scoliosis

BackgroundReducing the number of screw insertions while maintaining good clinical outcomes can improve the efficiency and cost-effectiveness of scoliosis surgery. However, the optimal minimum number of pedicle screws remains unclear. This study searched for factors to estimate the fewest number of pedicle screws required between end vertebrae in relation to preoperative main thoracic curve flexibility.MethodsSixty-nine subjects (4 male and 65 female, mean age: 14.8 ± 2.5 years) who underwent skip pedicle screw fixation for Lenke type 1–4 or 6 curves and were followed for at least 1 year were enrolled. Intervention technique was selected according to the size and flexibility of the preoperative main thoracic curve. Surgery-related variables included pedicle screw number, rod material and diameter, and extent of Ponte osteotomy. The effect on postoperative correction angle (i.e., the difference between the preoperative supine position maximum bending and postoperative standing Cobb angles of the main thoracic curve) according to surgical intervention technique was estimated using multiple linear mixed regression models with the preoperative supine position maximum bending correction angle (i.e., the difference between the standing preoperative and supine position maximum bending Cobb angles) as a random effect.ResultsThe preoperative maximum bending correction angle was 8–42° and had a moderate negative correlation with postoperative correction angle (r = ?0.65, P < 0.01). Multivariate analysis revealed a 1.7° (95% CI 0.7–2.6; P < 0.01) correction gain per single-screw insertion and a 1.8° (95% CI 0.5–3.1; P < 0.01) gain per intervertebral level in Ponte osteotomy.ConclusionsThe number of pedicle screws necessary to correct main thoracic adolescent idiopathic scoliosis curves can be estimated by calculating correction gains of 1.7° per pedicle screw and 1.8° per Ponte osteotomy intervertebral level. Based on these results, it may be possible to reduce invasiveness and cost for patients requiring a smaller degree of correction.     

3种椎弓根螺钉置钉方式治疗无神经损伤的胸腰椎压缩骨折疗效比较

目的比较经皮、经椎旁肌间隙(Wiltse入路)与传统开放3种椎弓根螺钉置钉方式治疗无神经损伤的胸腰椎压缩骨折的疗效。方法将148例单椎、无神经损伤的胸腰椎骨折(AO分型A型)患者根据手术方式不同分为A组(采用经皮椎弓根置钉,67例)、B组(采用Wiltse入路置钉,45例)、C组(采用传统开放置钉,36例)。比较3组手术情况、疼痛VAS评分及影像学参数。结果患者均获得随访,时间12~24个月。手术时间3组比较差异无统计学意义(P>0.05),术中出血量A、B组少于C组(P<0.05),X线透视次数A组多于B、C组(P<0.05)。术后1周及末次随访时,伤椎后凸Cobb角A组大于B、C组(P<0.05),伤椎前缘高度百分比A组低于B、C组(P<0.05)。术后3个月腰痛VAS评分A、B组低于C组(P<0.05)。结论3种椎弓根螺钉置钉方式均是治疗胸腰椎压缩骨折的有效方法,经皮椎弓根置钉和Wiltse入路置钉具有创伤小、患者恢复快、术后腰部疼痛程度轻的优点,但经皮椎弓根置钉术中医患放射线曝露时间长,椎体高度恢复及后凸角度恢复略差。