椎弓根螺钉在腰椎间盘突出症再手术中的应用

目的：探讨椎弓根螺钉在腰椎间盘突出症再手术中的应用价值。方法：对26例既往有腰椎间盘突出症手术史，术后复发经非手术治疗3～6月以上无效，疼痛剧烈，有明显神经根受压症状的病例，行后路腰椎间盘切除 椎弓根螺钉内固定 植骨融合术。结果：经1～6年随访，22例症状完全缓解，4例明显缓解。结论：椎弓根螺钉能改善腰椎间盘突出症复发再次手术后脊柱稳定性，减少腰椎间盘突出症术后复发。     

Feasibility and accuracy of computer-assisted individual drill guide template for minimally invasive lumbar pedicle screw placement trajectory

ObjectiveTo discuss the feasibility and accuracy of a specific computer-assisted individual drill guide template (CIDGT) for minimally invasive lumbar pedicle screw placement trajectory (MI-LPT) through a bovine cadaveric experimental study.DesignA 3-D reconstruction model, including lumbar vertebras (L1–L5), was generated, and the optimal MI-LPTs were determined. A drill guide template with a surface made of the antitemplate of the vertebral surface, including the spinous process and the entry point vertebral surface, was created by reverse engineering and rapid prototyping techniques. Then, MI-LPTs were determined by the drill guide templates, and the trajectories made by K-wires were observed by postoperative CT scan.SettingGeneral Hospital of Shenyang Military Area Command of Chinese PLA.ResultsIn total, 150 K-wires for MI-LPTs were successfully inserted into L1-L5. The required mean time and fluoroscopy times between fixation of the template to the spinous process, entry point vertebral surface, and insertion of the K-wires for minimally invasive lumbar pedicle screw placement trajectories into each vertebra were 79.4 ± 15.0 s and 2.1 ± 0.8 times. There were no significant differences between the preoperative plan and postoperative assessment in the distance from the puncture to the midline and inclination angles according to the different levels (P > 0.05, respectively). The mean deviation between the preoperative plan and postoperative assessment in the distance from the puncture to the midline and inclination angles were 0.8 ± 0.5 mm and 0.9 ± 0.5°, respectively.ConclusionsThe potential use of the novel CIDGT, which was based on the unique morphology of the lumbar vertebra to place minimally invasive lumbar pedicle screws, is promising and could prevent too much radiation exposure intraoperatively.     

椎弓根定位在治疗胸腰椎骨折中的临床意义

目的参照椎弓根解剖标志定位，利于椎弓根螺钉准确置入，达到脊柱后路钉棒系统连接内固定器，以有效治疗胸腰椎骨折。方法传统手术方式：暴露椎板、椎弓根生理窝、关节突、副突、横突，于椎弓根生理窝外缘咬平骨皮质，用椎弓根锥经咬平的皮质处与椎体终板平行呈内倾10°～15°角钻入椎弓根，到达椎体中央前中柱，置入椎弓根螺钉与连接器固定。结果23例胸腰椎骨折手术病人，共138个椎弓根定位和椎弓根螺钉内固定。CR片结果显示：定位准确，达到预先设计定位要求。结论尽管有C臂引导定位，但参照椎弓根解剖标志定位仍有现实的临床应用意义。     

下颈椎前路椎弓根皮质骨螺钉的解剖学研究

目的 测量正常成人下颈椎椎弓根的解剖学参数,探讨下颈椎前路椎弓根皮质骨螺钉内固定技术的可行性。 方法 随机选取80例正常成人颈椎CT影像资料,将扫描数据导入MIMICS 19.0软件。测量C3~C7椎体的椎弓根宽度（OPW）、椎弓根高度（OPH）、内侧皮质骨厚度（MCT）以及颈前路椎弓根皮质骨螺钉置钉参数,进行统计学分析。 结果 各节段左右两侧 OPH 和 MCT 参数的差异有统计学意义（P<0.05）。测量男性的 OPH 和 OPW 参数均大于女性,差异有统计学意义（P<0.05）。C3~C4进钉点位于椎体正中矢状面椎弓根的对侧1.0~3.0 mm,距椎体上终板平面1.0~3.5 mm;C5进钉点位于椎体正中矢状面椎弓根同侧或对侧1.0~2.0 mm,距椎体上终板平面3.0~4.0 mm;C6~C7进钉点位于椎体正中矢状面椎弓根的同侧2.0~4.5 mm,距椎体上终板平面4.5~7.0 mm。C3~C7的皮质骨螺钉总体内倾角平均值分别是：39.13°、41.00°、40.91°、37.28°、31.84°,总体矢状角是：90.85°、97.23°、108.97°、111.60°、104.83°。螺钉的直径为3.5 mm,长度选择30 mm,32 mm较为适宜。 结论 下颈椎前路椎弓根皮质骨螺钉内固定技术在理论上具有可行性,并总结出置钉规律,为其下一步的临床应用提供了理论依据。     

Pedicle screw fixation of the C7 vertebra using an anteroposterior fluoroscopic imaging technique

Cervical pedicle screws have been reported to be biomechanically superior to lateral mass screws. However, placement of these implants is a technical challenge. The purpose of this investigation was to use an anatomic and a clinical study to evaluate a technique for placement of the pedicle screws in the C7 vertebra using fluoroscopic imaging in only the anteroposterior (A/P) plane. Ten adult cadaver C7 vertebrae were used to record the pedicle width, inclination and a suitable entry point for placement of pedicle screws. A prospective study of 28 patients undergoing posterior instrumentation of the cervical spine with C7 pedicle screw placement was also performed. A total of 55 C7 pedicle screws were placed using imaging only in the A/P plane with screw trajectory values obtained by the anatomic study. Radiographs and CT scans were performed post-operatively. The average posterior pedicle diameter of C7 vertebra was 9.5 ± 1.2 mm in this study. The average middle pedicle diameter was 7.1 mm and the average anterior pedicle diameter was 9.2 mm. The average transverse pedicle angle was 26.8 on the right and 27.3 on the left. CT scans were obtained on 20 of 28 patients which showed two asymptomatic cortical wall perforations. One screw penetrated the lateral wall of the pedicle and another displayed an anterior vertebral penetration. There were no medial wall perforations. The preliminary results suggest that this technique is safe and suitable for pedicle screw placement in the C7 vertebra.     

Scoliosis in Duchenne’s muscular dystrophy: a changing trend in surgical management

A non-randomised retrospective study to compare the results of surgical correction of scoliosis in Duchenne’s muscular dystrophy (DMD) patients using three different instrumentation systems—Sublaminar instrumentation system (Group A), a hybrid of sublaminar and pedicle screw systems (Group B) and pedicle screw system alone (Group C). Between 1993 and 2003, 43 patients with DMD underwent posterior spinal fusion and instrumentation. Group A (n = 19) had sublaminar instrumentation system, Group B (n = 13) had a hybrid construct and Group C (n = 11) was treated with pedicle system. The mean blood loss in Group A was 4.1 l, 3.2 l in Group B and 2.5 l in Group C. Average operating times in Group A, B and C were 300, 274 and 234 min, respectively. Mean pre-operative, post-operative and final Cobb angle in Group A was 50.05 ± 15.46°, 15.68 ± 11.23° and 21.57 ± 11.63°, Group B was 17.76 ± 8.50°, 3.61 ± 2.53° and 6.69 ± 4.19° and Group C was 25.81 ± 9.94°, 5.45 ± 3.88°, 8.90 ± 5.82°, respectively. Flexibility index or the potential correction calculated from bending radiographs were 60 ± 6.33, 70 ± 4.65 and 67 ± 6.79% for Group A, Group B and Group C respectively. The percentage correction achieved was 72.5 ± 14.5% in Group A, 82 ± 6% in Group B and 82 ± 8% in Group C. The difference between percentage correction achieved and the flexibility index was 12.45 ± 8.22, 12.05 ± 1.3 and 15.00 ± 1.21% in Group A, B and C, respectively The percentage loss of correction in Cobb angles at final follow-up in Group A, B and C was 12.5 ± 3.5, 16.5 ± 1. and 12.5 ± 2.5%, respectively. Complications seen in Group A were three cases of wound infection and two cases of implant failure; Group B had a single case of implant failure and Group C had one patient with wound infection and one case with a partial screw pull out. Early surgery and smaller curve corrections appears to be the current trend in the management of scoliosis in DMD. This has been possible due to early curve detection and surgery thus having the advantage of less post-operative respiratory complications and stay in paediatric intensive care. Also, early surgery avoids development of pelvic deformity and extension of instrumentation to the pelvis thereby reducing blood loss. This trend reflects the advent of newer and safer instrumentation systems, advanced techniques in anaesthesia and cord monitoring. Sublaminar instrumentation system group had increased operating times and blood loss compared to both the hybrid and pedicle screw instrumentation systems due to increased bleeding from epidural vessels and pelvic instrumentation. Overall, the three instrumentation constructs appear to provide and maintain an optimal degree of correction at medium to long term follow up but the advantages of lesser blood loss and surgical time without the need for pelvic fixation seem to swing the verdict in favour of the pedicle screw system.     

New parameters to represent the position of the aorta relative to the spine for pedicle screw placement

Parameters of the position of the aorta in previous reports were determined for anterior surgery. This study evaluated the relative position of the aorta to the spine by new parameters, which could enhance the safety of pedicle screw placement. Three parameters were defined in a new Cartesian coordinate system. We selected an entry point of a left pedicle screw as the origin. The transverse plane was determined to include both the bases of the superior facet and to be parallel to the upper endplate of the vertebral body. A line connecting the entry points of both sides was defined as the X-axis. The angle formed by the Y-axis and a line connecting the origin and the center of the aorta was defined as the left pedicle–aorta angle. The length of a line connecting the origin and the aorta edge was defined as the left pedicle–aorta distance. Distance from the edge of the aorta to the X-axis was defined as the pedicular line–aorta distance. These parameters were measured preoperatively in 293 vertebral bodies of 24 patients with a right thoracic curve. We simulated the placement of the pedicle screw with variable length and with some direction error. We defined a warning pedicle as that when the aorta enters the expected area of the screw. Sensitivity analysis was performed to find the warning pedicle ratio in 12 scenarios. The left pedicle–aorta angle averaged 29.7° at the thoracic spine and −16.3° at the lumbar spine; the left pedicle–aorta distance averaged 23.7 and 55.2 mm; the pedicular line–aorta distance averaged 18.3 and 51.0 mm, respectively. The ratio of warning pedicles was consistently high at T4–5 and T10–12. When a left pedicle screw perforates an anterior/lateral wall of the vertebral body, the aorta may be at risk. These new parameters enable surgeons to intuitively understand the position of the aorta in surgical planning or in placement of a pedicle screw.     

The stabilizing potential of anterior, posterior and combined techniques for the reconstruction of a 2-level cervical corpectomy model: biomechanical study and first results of ATPS prototyping

Clinical studies reported frequent failure with anterior instrumented multilevel cervical corpectomies. Hence, posterior augmentation was recommended but necessitates a second approach. Thus, an author group evaluated the feasibility, pull-out characteristics, and accuracy of anterior transpedicular screw (ATPS) fixation. Although first success with clinical application of ATPS has already been reported, no data exist on biomechanical characteristics of an ATPS-plate system enabling transpedicular end-level fixation in advanced instabilities. Therefore, we evaluated biomechanical qualities of an ATPS prototype C4–C7 for reduction of range of motion (ROM) and primary stability in a non-destructive setup among five constructs: anterior plate, posterior all-lateral mass screw construct, posterior construct with lateral mass screws C5 + C6 and end-level fixation using pedicle screws unilaterally or bilaterally, and a 360° construct. 12 human spines C3–T1 were divided into two groups. Four constructs were tested in group 1 and three in group 2; the ATPS prototypes were tested in both groups. Specimens were subjected to flexibility test in a spine motion tester at intact state and after 2-level corpectomy C5–C6 with subsequent reconstruction using a distractable cage and one of the osteosynthesis mentioned above. ROM in flexion–extension, axial rotation, and lateral bending was reported as normalized values. All instrumentations but the anterior plate showed significant reduction of ROM for all directions compared to the intact state. The 360° construct outperformed all others in terms of reducing ROM. While there were no significant differences between the 360° and posterior constructs in flexion–extension and lateral bending, the 360° constructs were significantly more stable in axial rotation. Concerning primary stability of ATPS prototypes, there were no significant differences compared to posterior-only constructs in flexion–extension and axial rotation. The 360° construct showed significant differences to the ATPS prototypes in flexion–extension, while no significant differences existed in axial rotation. But in lateral bending, the ATPS prototype and the anterior plate performed significantly worse than the posterior constructs. ATPS was shown to confer increased primary stability compared to the anterior plate in flexion–extension and axial rotation with the latter yielding significance. We showed that primary stability after 2-level corpectomy reconstruction using ATPS prototypes compared favorably to posterior systems and superior to anterior plates. From the biomechanical point, the 360° instrumentation was shown the most efficient for reconstruction of 2-level corpectomies. Further studies will elucidate whether fatigue testing will enhance the benefit of transpedicular anchorage with posterior constructs and ATPS.     

后路短节段固定联合伤椎置钉在胸腰段脊柱骨折中的应用

目的观察后路短节段固定联合伤椎置钉在治疗胸腰段脊柱骨折中的近期临床效果。方法对收治的43例胸腰段脊柱骨折患者采用后路短节段内固定联合伤椎置钉方法进行治疗,对患者术前及术后椎体高度及后凸角度分别进行测定并比较。结果本组患者手术均较成功,无1例出现术后并发症,椎体高度及后凸角度较治疗前显著改善,差异有统计学意义(P<0.05)。结论后路短节段固定联合伤椎置钉治疗胸腰段脊柱骨折手术创伤小,可达到良好的复位效果,有效纠正后凸畸形,值得临床推广使用。     

经伤椎置钉与跨伤椎椎弓根螺钉内固定治疗胸腰椎爆裂骨折疗效比较

目的回顾性分析比较经伤椎置钉与跨伤椎椎弓根螺钉内固定治疗胸腰椎爆裂骨折的临床疗效。方法本组91例胸腰椎爆裂型骨折患者,其中经伤椎置钉患者43例,跨伤椎置钉患者48例,本组均采用后入路经椎弓根置螺钉内固定术,分别在术前、术后2周、术后3个月、术后6个月进行疼痛视觉模拟评分（VAS）、椎体高度压缩率及伤椎Cobb’s角测量分析,两组进行对比。结果本组随访6～24个月。术前、术后2周两组之间的VAS评分、椎体高度压缩率及伤椎Cobb’s角比较,差异无显著统计学意义（P〉0．05）。术后3个月、术后6个月两组之间的VAS评分、椎体高度压缩率及伤椎Cobb’s角比较,差异有显著统计学意义（P〈0．01）。结论经伤椎置钉椎弓根螺钉内固定术是治疗胸腰椎爆裂型骨折比较安全有效的方法,可以增强内固定系统的牢固性,减少术后并发症,远期疗效肯定。