Verification of the position of pedicle screws in lumbar spinal fusion

Medial or lateral pedicle screw penetration with the potential to affect neural structures in a well-known and frequent problem associated with posterior spinal fusion. We evaluated the placement of pedicle screws (n = 141) in 36 patients following posterior lumbar spinal fusion with Socon or Kluger instrumentation via a lateral transpedicular approach. The examination was based on CT and MR images performed after removal of the instrumentation, on average 1 year after implantation. We found seven pedicle screws with lateral cortical penetration of the pedicle and five screws with medial cortical penetration of the pedicle (8.5% pedicle penetration overall). No severe radicular complications accompanied these pedicle penetrations. The mean insertion angles of the pedicle screws at the L4 level were 22.6° and 23.1° for the left and the right side, respectively. At the L5 level the mean insertion angle was 20.5° on the left side and 21.5° on the right, and at the S1 level the mean angle was 16.2° on the left and 15.2° on the right. The results of this study indicate that the lateral transpedicular approach is a safe procedure for pedicle screw insertion.     

Accuracy of pedicle and mass screw placement in the spine without using fluoroscopy: a prospective clinical study.

BACKGROUND CONTEXT: Spinal instrumentation is accompanied by various problems, including screw malpositioning. One way of preventing this is the employment of intraoperative biplanar fluoroscopy. However, screw malpositioning despite the use of fluoroscopy has been reported, and exposure to radiation is another burden of this method. Therefore, the purpose of this article was to compare the results of instrumentation applications without using scopy versus the harmful effects of radiation exposed during spinal instrumentation. PURPOSE: The aim of this article was to review the literature and this is the first prospective clinical study performed on this subject. STUDY DESIGN: Patient report. PATIENT SAMPLE: One hundred thirty-two patients with spinal instrumentations were included. OUTCOME MEASURES: Radiological investigation with computed tomography (CT) scans was performed 2 days after the procedure. METHODS: Craniosacral posterior spinal instrumentation was performed without using scopy at the Neurosurgery Clinic of Haseki Training and Research Hospital between January 2000 and January 2005. Postoperative CT analyses were performed to evaluate whether the 527 screws used during posterior instrumentation in a total of 132 patients were positioned correctly. In all cases, the screw applications were performed with regard to anatomic landmarks, whereas the distances were determined according to lesion localizations. Screw malpositioning and the functional effects and relations with interactions with neurovascular structures were examined. At the end of the operations, all patients were examined with direct lateral roentgenograms and CT scans for the evaluation of screw positions. RESULTS: According to their locations, 75 cervical screwing in 24 patients, 32 upper thoracic screwing in 7 patients, 30 midthoracic screwing in 7 patients, 306 thoracolumbar screwing in 54 patients, and 84 sacral screwing in 40 patients were performed by the senior spinal surgeon (KK). Among all posterior spinal instrumentation applications, the cervical region analyses revealed penetration of the medial wall of vertebral foramen with two (0.4%) screws, penetration of the lateral wall with one (0.2%) screw, and protrusion into the vertebral foramen without vascular penetration with one (0.2%) screw, whereas in the upper thoracic region there was penetration into the lateral pedicle wall with one (0.2%) screw and deviation toward the disc space through the superior end plate with two (0.4%) screws. In the midthoracic region, there was penetration into the disc space with two (0.4%) screws in only one case, whereas in the thoracolumbar complex, there was deviation toward the superior end plate with seven (1.4%) screws in four cases, deviation toward the disc space with two (0.4%) screws, medial wall penetration with six (1.2%) screws (two of which caused nerve root irritation in three cases), and penetration of the lateral wall of pedicle with four (0.8%) screws. In the sacral instrumentations, malpositioning occurred with only two (0.4%) screws because of deviation toward the medial wall. In summary, malpositioning occurred with 30 (5.6%) of the total 527 screws; none of the cases had neural or vascular damage. Two (1.5%) cases were revised for malpositioning and distance errors. The mean duration for preparation of screw introduction site and placement of the screw was 3 minutes. Infection occurred in only one (0.75%) case. CONCLUSIONS: Screw application without fluoroscopy is performed with calculation of all essential anatomic details, and because of the reduction of surgery time, the absence of exposure to radiation, and very low infection rates as a consequence of reduced surgery time, it is a method recommendable for surgeons experienced with screw placement. Besides, its malpositioning rates are within acceptable limits. Because screw malpositioning is also found after biplanar fluoroscopy, the prevention of screw malpositioning requires knowing the anatomic landmarks accurately.     

Radiologic and computerized tomography evaluation of pedicle screw placement in lumbar spondylodesis

PURPOSE: To determine the accuracy of a standard roentgenogram for the placement control of pedicle screws following spinal fusion. METHOD: From 1995 to 1997 we performed computed tomography (CT) after material removal following lumbar and lumbosacral spinal fusion in 16 patients. We compared the placement of the 76 pedicle screws in plain X-rays after spinal fusion with their appearance on CT. A correct placement was defined as no penetration of the pedicle cortex, no contact of the lateral or ventral cortex of the vertebral body or joint, and a sufficient screw length. RESULTS: We found correct placement of 58 screws (76.3%) on the standard roentgenogram, whereas by CT only 46 (60.5%) were placed correctly. The results of both radiological examinations correlated (correct/incorrect placement) for only 54 screws (71.1%). A penetration of the ventral cortex of the vertebral body in 21 cases (27.6%) was identified in only 11 screws (14.5%) on the postoperative X-rays. The two radiological methods in this instance correlated for 62 screws (81.6%). CONCLUSION: The value of postoperative standard roentgenogram for the placement control of pedicle screws following spinal fusion is low. By this method possible contact with the aorta, vena cava, dura or vertebral joint cannot sufficiently be excluded.     

经皮植入椎弓根螺钉的CT扫描钉道分析和临床评价

目的：通过应用经皮穿刺植入椎弓根螺钉的后路固定系统治疗胸腰段骨折患者，以探究该微创技术的准确性和可行性。方法：应用菲力浦X线荧屏透视，经皮穿刺植入导针引导的空心椎弓根螺钉136枚，后路固定系统治疗胸腰段骨折34例。术后CT扫描观察钉道与椎弓根内侧壁、外侧壁的关系，钉尖与椎体前缘的距离、TSA角、SSA角，以及进行术后的初步临床疗效观察。结果：其中椎弓根内侧壁破裂4枚，椎弓根外侧壁破裂3枚，经皮椎弓根螺钉方向过于向头端偏斜2枚，过于向尾端偏斜1枚，经皮椎弓根螺钉钉尖稍穿透椎体前缘5枚，本组经皮椎弓根螺钉植钉失误率7．25％。结论：该技术具有一定的准确性和可行性，并发症发生率相对可以接受，但有较高操作要求，需要有经验的脊柱外科医生进行。本组病例在X线荧屏透视下完成，受辐射量大，后来植钉时透视次数明显减少，患者和医师受辐射量下降而且手术时间缩短，如结合导航技术将在微创脊柱外科领域中发挥相当作用。     

Factors affecting the accurate placement of percutaneous pedicle screws during minimally invasive transforaminal lumbar interbody fusion

We retrospectively evaluated 488 percutaneous pedicle screws in 110 consecutive patients that had undergone minimally invasive transforaminal lumbar interbody fusion (MITLIF) to determine the incidence of pedicle screw misplacement and its relevant risk factors. Screw placements were classified based on postoperative computed tomographic findings as “correct”, “cortical encroachment” or as “frank penetration”. Age, gender, body mass index, bone mineral density, diagnosis, operation time, estimated blood loss (EBL), level of fusion, surgeon’s position, spinal alignment, quality/quantity of multifidus muscle, and depth to screw entry point were considered to be demographic and anatomical variables capable of affecting pedicle screw placement. Pedicle dimensions, facet joint arthritis, screw location (ipsilateral or contralateral), screw length, screw diameter, and screw trajectory angle were regarded as screw-related variables. Logistic regression analysis was conducted to examine relations between these variables and the correctness of screw placement. The incidence of cortical encroachment was 12.5% (61 screws), and frank penetration was found for 54 (11.1%) screws. Two patients (0.4%) with medial penetration underwent revision for unbearable radicular pain and foot drop, respectively. The odds ratios of significant risk factors for pedicle screw misplacement were 3.373 (95% CI 1.095–10.391) for obesity, 1.141 (95% CI 1.024–1.271) for pedicle convergent angle, 1.013 (95% CI 1.006–1.065) for EBL >400 cc, and 1.003 (95% CI 1.000–1.006) for cross-sectional area of multifidus muscle. Although percutaneous insertion of pedicle screws was performed safely during MITLIF, several risk factors should be considered to improve placement accuracy.     

Clinical evaluation and computed tomography scan analysis of screw tracts after percutaneous insertion of pedicle screws in the lumbar spine

STUDY DESIGN: An examination of the accuracy of percutaneous pedicle screw placement in the lumbar spine. Using computed tomography scan analysis after implant removal, the screw tracts could be analyzed regarding the degree and direction of screw dislocation. OBJECTIVES: To investigate the misplacement rate and related clinical complications of percutaneous pedicle screw insertion in the lumbar spine. SUMMARY OF BACKGROUND DATA: The feasibility of the external fixation test has been investigated in several studies. Although pedicle screw misplacement has been reported as one of the main complications, there are no reliable data on the misplacement rate for this difficult surgical procedure. METHODS: In this study, 51 consecutive patients with suspected segmental instability were investigated after external transpedicular screw insertion for the external fixation test. Computed tomography scans of all instrumented pedicles from L2 to S1 were performed after screw removal. The screw tracts were analyzed, and the direction and degree of the pedicle violations were noted. In addition, the screw and pedicle angles were measured. RESULTS: Of 408 percutaneously inserted pedicle screws, only 27 screws (6.6%) were misplaced. There were 19 medial pedicle violations, 6 lateral cortical defects, and only 1 cranial and 1 caudal displacement. With respect to the spinal level, S1 showed the highest misplacement rate, with 11 screw dislocations (12%). After surgery, found two nerve root injuries were found. Only one of the injuries (L4) was related to the malposition of a screw. CONCLUSIONS: This study has shown that percutaneous insertion of pedicle screws in the lumbar spine is a safe and reliable technique. Despite the low misplacement rate of only 6.6%, it should be kept in mind that the surgical procedure is technically demanding and should be performed only by experienced spine surgeons.     

O-arm计算机导航辅助脊柱椎弓根螺钉置入的准确性

[目的]分析O-arm计算机辅助导航技术在脊柱椎弓根螺钉置入的准确性。[方法]回顾性分析2017年1月~2018年9月本院椎弓根螺钉置入患者575例,根据椎弓根螺钉置入方式不同,分为两组。导航组采用O-arm计算机辅助导航技术系统置入椎弓根螺钉233例,传统组采用传统徒手法置入椎弓根螺钉342例。行CT检查,依据Neo分型评估置钉准确性。[结果]导航组共置入1459枚椎弓根螺钉,其中C1~7置入222枚,T1~12置入535枚,L1~5置入652枚,S1置入50枚。每名患者置钉数量1~24枚,平均(6.26±3.77)枚。传统组共置入1724枚椎弓根螺钉,其中C1~7置入269枚,T1~12置入601枚,L1~5置入785枚,S1置入87枚。每名患者置钉数量1~20枚,平均(5.67±4.11)枚。导航组全部病例顺利完成手术,术中无血管、神经损伤等并发症,置钉安全率为100%,传统组有4例发生血管、神经损伤等并发症。所有患者术后进行12~24个月随访,随访过程均未发生不良事件。依据CT影像Neo分级标准,导航0型及1型椎弓根螺钉的成功置入率达98.01%,而传统组0型及1型椎弓根螺钉的成功置入率91.85%;两组间置入螺钉准确性的差异具有统计学意义(P<0.05)。[结论]与传统C臂X线机等徒手置钉方式相比,O-arm计算机辅助导航技术可提高脊柱椎弓根螺钉置入准确性,同时降低神经、血管等并发症的发生。     

The placement of lumbar pedicle screws using computerised stereotactic guidance.

Computer-assisted frameless stereotactic image guidance allows precise preoperative planning and intraoperative localisation of the image. It has been developed and tested in the laboratory. We evaluated the efficacy, clinical results and complications of placement of a pedicle screw in the lumbar spine using this technique. A total of 62 patients (28 men, 34 women) had lumbar decompression and spinal fusion with segmental pedicle screws. Postoperative CT scans were taken of 35 patients to investigate the placement of 330 screws. None showed penetration of the medial or inferior wall of a pedicle. Registration was carried out 66 times. The number of fiducial points used on each registration averaged 5.8 (4 to 7) The mean registration error was 0.75 mm (0.32 to 1.72). This technique provides a safe and reliable guide for placement of transpedicular screws in the lumbar spine.     

In vivo accuracy of thoracic pedicle screws.

STUDY DESIGN: A retrospective observational study of 279 transpedicular thoracic screws using postoperative computed tomography (CT). OBJECTIVE: To determine the accuracy of transpedicular thoracic screws. SUMMARY OF BACKGROUND DATA: Previous studies have reported the importance of properly placed transpedicular thoracic screws. To our knowledge, the in vivo accuracy of pedicle screw placement throughout the entire thoracic spine by CT is unknown. METHODS: The accuracy of thoracic screw placement within the pedicle and vertebral body and the resultant transverse screw angle (TSA) were assessed by postoperative CT. Cortical perforations of the pedicle were graded in 2-mm increments. Screws were regionally grouped for analysis. RESULTS: Forty consecutive patients underwent instrumented posterior spinal fusion using 279 titanium thoracic pedicle screws of various diameters (4.5-6.5 mm). The regional distribution of the screws was 39 screws at T1-T4, 77 screws at T5-T8, and 163 screws at T9-T12. Fifty-seven percent of screws were totally confined within the pedicle. Although medial perforation of the pedicle wall occurred in 14% of screws, in <1% there was >2 mm of canal intrusion. Lateral pedicular perforation occurred in 68% of perforating screws and was significantly more common than medial perforation (P < 0.0005). Seventeen screws penetrated the anterior vertebral cortex by an average of 1.7 mm. Screws inserted between T1 and T4 had a decreased incidence of full containment within the pedicle (P < 0.0005) and vertebral body (P = 0.039) compared with T9-T12. The mean TSA for screws localized within the pedicle was 14.6 degrees and was significantly different from screws with either medial (mean 18.0 degrees ) or lateral (mean 11.5 degrees ) pedicle perforation (P < 0.0005). Anterior vertebral penetration was associated with a smaller mean TSA of 10.1 degrees (P = 0.01) and with lateral pedicle perforation (P < 0.0005). There were no neurologic or vascular complications. CONCLUSIONS: Ninety-nine percent of screws were fully contained or were inserted with either < or =2 mm of medial cortical perforation or an acceptable lateral breech using the "in-out-in" technique. Anterior cortical penetration occurred significantly more often with lateral pedicle perforation and with a smaller mean TSA. The incidence of fully contained screws was directly correlated with the region of instrumented thoracic spine.     

Placement and complications of cervical pedicle screws in 144 cervical trauma patients using pedicle axis view techniques by fluoroscope

Cervical pedicle screw fixation is an effective procedure for stabilising an unstable motion segment; however, it has generally been considered too risky due to the potential for injury to neurovascular structures, such as the spinal cord, nerve roots or vertebral arteries. Since 1995, we have treated 144 unstable cervical injury patients with pedicle screws using a fluoroscopy-assisted pedicle axis view technique. The purpose of this study was to investigate the efficacy of this technique in accurately placing pedicle screws to treat unstable cervical injuries, and the ensuing clinical outcomes and complications. The accuracy of pedicle screw placement was postoperatively examined by axial computed tomography scans and oblique radiographs. Solid posterior bony fusion without secondary dislodgement was accomplished in 96% of all cases. Of the 620 cervical pedicle screws inserted, 57 (9.2%) demonstrated screw exposure (<50% of the screw outside the pedicle) and 24 (3.9%) demonstrated pedicle perforation (>50% of the screw outside the pedicle). There was one case in which a probe penetrated a vertebral artery without further complication and one case with transient radiculopathy. Pre- and postoperative tracheotomy was required in 20 (13.9%) of the 144 patients. However, the tracheotomies were easily performed, because those patients underwent posterior surgery alone without postoperative external fixation. The placement of cervical pedicle screws using a fluoroscopy-assisted pedicle axis view technique provided good clinical results and a few complications for unstable cervical injuries, but a careful surgical procedure was needed to safely insert the screws and more improvement in imaging and navigation system is expected.     

胸椎椎弓根螺钉植入位置的分区及临床意义

目的 探讨术后CT扫描对胸椎椎弓根螺钉位置分区及其临床意义。方法对64例共450枚胸椎椎弓根螺钉固定患者的临床资料进行统计分析。所有患者术后均采用手术节段椎弓根CT扫描,根据椎弓根螺钉在CT片显示的位置及可能引起的危险将其分为A、B、C三个区：A区,螺钉位置正常（椎弓根螺钉位于椎弓根中央,未穿透椎弓根和椎体,深度合适）。B区,螺钉引起椎弓根部分皮质破裂或穿透椎体前方或侧方,但没有引起严重的神经或血管损害。同时,将椎弓根螺钉偏向椎弓根外侧或上方、内侧或下方、穿透椎体前方或侧方分别划分为B1、B2、B3三个部分。C区,椎弓根螺钉位置严重偏差,直接威胁脊髓、神经根或大血管。平均随访时间25．8个月。比较胸椎不同位置使用椎弓根螺钉固定时椎弓根螺钉的准确位置及术后可能因为椎弓根螺钉位置偏差引起的并发症。结果A区共367枚（81．6％）,B区78枚（17．3％）,其中B,区40枚（8．8％）、B2区23枚（5．1％）、B3区15枚（3．4％）,C区5枚（1．1％）。从结果看T3-6节段最容易发生椎弓根螺钉的位置错误。结论根据CT扫描影像结果对椎弓根螺钉位置进行分区,有助于准确判断椎弓根螺钉的位置,预防并发症的发生。     

Lumbar pedicle screw placement: Using only AP plane imaging

Background:

Variations in the pedicle morphology and presence of spinal deformities can make pedicle screw placement challenging. Recently, computerized tomography (CT) guided screw placement has reportedly improved the surgical accuracy of pedicle screw insertion. However, it is time consuming and expensive. We combined single-plane fluoroscopy in AP projection alone with tactile guidance for placing pedicle screws more efficiently and accurately. This report presents our results with this technique.

Materials and Methods:

An Institutional Review Board (IRB) approved retrospective study was carried out on 308 patients who underwent lumbar spinal fusion with 1806 pedicle screws placed using fluoroscopy only in the AP plane. There were 182 patients with two-level fusion, 79 with single-level fusion, 26 with three-level fusion, and 21 with more than three-level fusions. The indications of surgery included spondylolisthesis, adult scoliosis, revision surgery, lumbar canal stenosis, and discogenic pain. Pedicle screws were inserted under fluoroscopic guidance in the AP plane alone with a final lateral image after completion of implant placement. Radiographs were performed postoperatively in all patients and CT scans were obtained on 78 patients with 588 screws.

Results:

Twenty nine (5%) cortical wall perforations were noted amongst the 588 screws that were evaluated with a CT scan and did not result in postoperative vascular or neural complications. Anterior cortical vertebral violation was noted in 14 patients, while in 9 patients the screws penetrated the lateral wall of the pedicle. The medial wall of the pedicle was encroached in six patients with no frank perforations.

Conclusion:

Placement of pedicle screws under fluoroscopic guidance using AP plane imaging alone with tactile guidance is safe, fast, and reliable. However, a good understanding of the radiographic landmarks is a prerequisite.     

Triggered electromyographic threshold for accuracy of thoracic pedicle screw placement in a porcine model.

STUDY DESIGN: A porcine model of thoracic pedicle screw insertion was used to determine the effect of screw position on triggered electromyographic response. OBJECTIVE: To develop a model of intraoperative detection of misplaced thoracic pedicle screws. SUMMARY OF BACKGROUND DATA: Triggered electromyographic stimulation has been a valuable aid in determining appropriate placement of lumbar pedicle screws. The use of pedicle screws is increasing in the thoracic spine. Misplaced thoracic pedicle screws may have significant implications if the spinal cord is injured. This study was an attempt to determine whether the established lumbar model can be used for thoracic pedicle screws. METHODS: Five 120- to 150-lb domestic pigs had 85 pedicle screws placed bilaterally in the thoracic spine at each level from T6 to T15. Screws were inserted entirely in the pedicle (Group A). After removal of the medial pedicle wall, the screws were reinserted in the pedicle with no neural contact (Group B). The screws were then placed with purposeful contact with the neural elements (Group C). The screws were stimulated, eliciting an electromyographic response in the intercostal muscles for each instrumented level. The type of response noted was classified as either primary (response from appropriate nerve root), secondary (response at different root) or no response (response at different root, no response at appropriate root). RESULTS: Two hundred fifty responses were recorded. A primary response was noted in 72% of recordings. There was a relatively consistent decrease in the triggered electromyographic response from Group A (mean 4.15 +/- 1.80 mA) to Group C (mean 3.02 +/- 2.53 mA) screws (P = 0.0003). There was little difference in the response obtained from Group A to Group B (mean 4.37 +/- 2.48 mA) screws (P > 0.05). When a primary response was recorded, the mean threshold electromyographic response recorded was significantly lower than recordings with secondary and no response recordings (P < 0.05). CONCLUSION: Even though there was a consistent decrease between the A and C screws that was more definitively separated when a primary response was elicited, it was not possible to determine a cutoff trigger electromyographic level that would consistently differentiate intraosseous from epidural pedicle screw placement. Furthermore, this method could not differentiate screws clearly in the pedicle from screws with medial pedicle wall breakthrough. A more direct method of spinal cord monitoring must be established to provide the surgeon with early warning of the potential of neural injury in the placement of thoracic pedicle screws.     

Cervical and upper thoracic screwing for spinal fusion: strategy for its safe insertion to avoid major complications

There are several screwing techniques to attain cervical fusion such as pedicle screw, lateral mass screw, facet screw, transarticular and laminar screw. Each screwing technique has advantages and disadvantages. In this study, we introduce our strategy for safe screwing and its clinical results. Our strategy is as follows: lateral mass screw for C1, 3, 4, 5, 6 and pedicle screw for C2, 7, and thoracic level. When the C2 pedicle is thinner than 3.5 mm, we use C2 laminar screws. We do not use Magerl transarticular screw or facet screw; 146 screws were inserted in 17 patients. There were no major complications such as spinal cord and nerve root injury. We did not observe vertebral arterial injury either. Of the 146 screws, 141 (97.0%) were accurately inserted. As for lateral mass screwing by Roy-Camille’s technique and C2 laminar screwing, all screws were inserted in the appropriate site (100%) without any complications. Five pedicle screws were misplaced. Of the 57 pedicle screws, 5 showed a minor tear of the wall at C7, Th1 and Th3, the success rate for all pedicle screws was 91%. All showed solid fusion. For cervical screwing the most important aspect should be safety to avoid severe morbidity. Our strategy, which consists in the combined use of pedicle, lateral mass and laminar screwing, is safe and reliable.     

Accuracy and safety of free-hand pedicle screw fixation in age less than 10 years

Background:

Pedicle screws are being used commonly in the treatment of various spinal disorders. However, use of pedicle screws in the pediatric population is not routinely recommended because of the risk of complications. The present study was to evaluate the safety of pedicle screws placed in children aged less than 10 years with spinal deformities and to determine the accuracy and complication (early and late) of pedicle screw placement using the postoperative computed tomography (CT) scans.

Materials and Methods:

Thirty one patients (11 males and 20 females) who underwent 261 pedicle screw fixations (177 in thoracic vertebrae and 84 in lumbar vertebrae) for a variety of pediatric spinal deformities at a single institution were included in the study. The average age of patients was 7 years and 10 months. These patients underwent postoperative CT scan which was assessed by two independent observers (spine surgeons) not involved in the treatment.

Results:

Breach rate was 5.4% (14/261 screws) for all pedicles. Of the 177 screws placed in the thoracic spine, 13 (7.3%) had breached the pedicle, that is 92.7% of the screws were accurately placed within pedicles. Seven screws (4%) had breached the medial pedicle wall, 4 screws (2.3%) had breached the lateral pedicle wall and 2 screws (1.1%) had breached the superior or inferior pedicle wall respectively. Of the 84 screws placed in the lumbar spine, 83 (98.8%) screws were accurately placed within the pedicle. Only 1 screw (1.2%) was found to be laterally displaced. In addition, the breach rate was found to be 4.2% (11/261 screws) with respect to the vertebral bodies. No neurological, vascular or visceral complications were encountered.

Conclusions:

The accuracy of pedicle screw placement in pedicles and vertebral bodies were 94.6% and 95.8% respectively and there was no complication related to screw placement noted until the last followup. These results suggest that free-hand pedicle screw fixation can be safely used in patients younger than 10 years to treat a variety of spinal disorders.     

多层螺旋CT三维重建技术辅助脊柱经椎弓根内固定手术

目的研究多层螺旋CT三维重建技术辅助脊柱经椎弓根内固定手术的方法。方法对68例脊柱经椎弓根内固定手术患者行多层螺旋CT薄层扫描后进行容积重建（VR）及多平面重建（MPR）,据此进行辅助诊断、术前计划及个体化测量以指导手术,并在术后评估效果。结果多层螺旋CT三维重建技术辅助下置入椎弓根钉366枚,包括颈椎168枚,胸椎52枚,腰椎146枚。术后复查CT,20枚（5.46%）钉发生超过＂安全区域＂范围的椎弓根穿破,其中颈椎11枚（11/168）发生1～2mm的穿破,1枚（1/168）穿破外侧壁2.2mm,但未出现临床症状,胸椎1枚（1/52）、腰椎7枚（7/146）存在2～4mm的穿破。所有病例术后未发生与置钉相关的脊髓、神经、血管并发症。结论应用多层螺旋CT扫描三维重建辅助脊柱经椎弓根内固定手术,可以量化、个体化确定手术参考指标,提高手术的安全性和准确性。     

青少年脊柱侧凸患者胸椎椎弓根螺钉置入的准确性和安全性评价

目的：探讨青少年脊柱侧凸患者胸椎椎弓根螺钉置入的准确性和安全性，以减少相关手术并发症。方法：32例青少年脊柱侧凸患者术前均对畸形脊柱进行标准俯卧位CT加密扫描，测量进钉点至椎体前缘的深度、进针角度、椎弓根直径和椎体的旋转角度，根据测得数据确定椎弓根螺钉置入的深度和方向，置入螺钉后再行脊柱全长X线片及CT扫描评价置钉的准确性和安全性。结果：32例共置入226枚胸椎椎弓根螺钉，术后CT加密和X线片观察到205枚螺钉（90．7％）完全在椎弓根皮质骨内。10例21枚螺钉（9.3％）发生错置，7枚螺钉（3．1％）偏外，5枚螺钉（2．2％）偏前外侧（其中2枚螺钉靠近节段血管），4枚螺钉（1．8％）偏下，4枚螺钉（1．8％）直径过大导致椎弓根内壁膨胀内移，1枚螺钉（0．4％）误入椎管导致完全性脊髓损伤。T1～T4错置12枚（18．2％），T5～T12错置9枚（6．1％）；凸侧椎根螺钉置入的准确率为93．8％，凹侧为83．1％。结论：脊柱畸形患者术前应常规采用标准俯卧位CT加密扫描，根据扫描图像测得的相关数据可为术中准确置入椎弓根螺钉提供重要参考依据。在青少年脊柱侧凸患者胸椎椎弓根螺钉置入有一定的误置率，螺钉发生错置多见于上胸椎和凹侧．术中应高度重视。     

球形探针技术在胸腰椎椎弓根螺钉置钉中的应用

目的通过与传统开路锥置钉技术比较,评价在胸腰椎椎弓根螺钉置钉中应用球形探针技术的准确性和安全性,探讨其临床应用价值。方法回顾性分析2016年1月—2017年2月新疆医科大学第一附属医院收治的需行胸腰椎椎弓根螺钉内固定治疗的106例患者临床资料,术中应用球形探针技术或传统开路锥技术置入椎弓根螺钉。其中56例采用直径2.5 mm球形探针穿刺(球形探针组),其余50例采用传统开路锥穿刺(传统组)。术后采用CT检查确认螺钉位置以评估置钉准确性。结果球形探针组共置入椎弓根螺钉296枚,传统组共置入264枚。术后CT显示球形探针组置钉准确率为97.64%,7枚置钉不良;传统组置钉准确率为83.71%,43枚置钉不良。2组置钉准确率及穿透椎弓根内侧、椎弓根外侧、椎体前壁骨皮质螺钉比例差异均有统计学意义(P<0.05)。2组术中出血量间差异无统计学意义(P>0.05)。传统组术后1例出现L5神经根损伤致足下垂;球形探针组术中、术后均未出现神经、血管、脑脊液漏或内脏损伤等并发症。结论与传统开路锥置钉技术相比,球形探针技术能更准确置入胸腰椎椎弓根螺钉,减少因螺钉位置不良导致的并发症。     

青少年特发性脊柱侧凸椎弓根螺钉的误置模式及危险因素

目的 评估青少年特发性脊柱侧凸(AIS)椎弓根螺钉不良置入的模式并分析其原因.方法 收集从2008年7月至9月行后路椎弓根螺钉固定的70例AIS患者的临床资料,其中男性12例,女性58例;年龄12～19岁,平均(14.5±2.7)岁;术前Cobb角40°～125°,平均62.0°±18.2°.术中根据解剖标志徒手置入椎弓根螺钉,所有患者术后均行CT检查.在PACS系统上通过PacsClient软件测量螺钉穿破椎弓根内、外壁以及椎体前缘的距离.定义穿破任一壁超过2 mm为不良置钉.不良置钉中穿破内壁超过4 mm或钉尖使主动脉变形定义为高危置钉.对数据进行统计学分析,探讨不良置钉的危险因素.结果 共置入椎弓根螺钉1030枚,胸椎773枚,腰椎257枚.不良置钉108枚(10.5%),其中穿破外壁35枚,穿破内壁56枚,穿破椎体前缘33枚(其中有16枚既穿破了椎体前缘又穿破了外壁).高危置钉16枚(1.6%).顶椎、顶椎近端第5节段和顶椎远端第4节段的不良置钉率高于其他节段,其中顶椎左侧和顶椎近端第5节段右侧不良置钉率均高于对侧.顶椎区高危置钉率最高,达4.8%.Cobb角>90°组不良置钉率高于Cobb角40°～90°组,椎体旋转Ⅲ～Ⅳ度组不良置钉率高于椎体旋转0～Ⅱ度组.结论 AIS不良置钉集中在顶椎、顶椎近端第5节段和顶椎远端第4节段3个区域,高危置钉多发生在顶椎区,危险因素包括Cobb角大小、旋转程度以及与顶椎的距离.     

A five-step remedial screw placement method to treat severe spinal deformity with free-hand transpedicular screw placement

Purpose

Severe spinal deformity is a complex morphological deformation that occurs and develops in three-dimensional space combined with abnormal development and morphology of anatomical structures, which presents great difficulties in the process of transpedicular screw placement. This study tried to explore the methods of transpedicular screw placement in surgical correction of severe spinal deformities.

Methods

Surgical corrections through posterior approach were performed in all the 76 cases (mean age 20.4 years). The averaging preoperative Cobb’s angle of scoliosis was 108.2° ± 33.6° (range 100°–170°). Among these patients, 34 cases were combined with kyphosis; the average Cobb’s angle of kyphosis was 77.3° (range 63°–160°). During operation, the screw tract was first established with the regular free-hand pedicle screw placement method. When this failed, in order to adjust the screw trajectory, a five-step remedial method was performed in the following order: (1) the“funnel” method; (2) exploring the pedicle exterior edge through the costotransverse joint; (3) exploring the superior and inferior edges of pedicle through the nerve root canal; (4) the vertebral plate fenestration; and (5) hemilaminectomy.

Results

Among all 1,472 screws planned to be placed for the patients, 1,210 (82.2 %) were successfully placed after using the regular method, and 262 (17.8 %) failed in this stage. After applying the five-step remedial method, 256 of the failed 262 screws were successfully placed. Among them, 176 screws (68.8 %) were successfully placed after Step 1, 44 (17.2 %) after Step 2, 21 (8.2 %) after Step 3, 12 (4.7 %) after Step 4, and 3 (1.2 %) after Step 5. In only six, pedicles screws could not be placed eventually. No nerve or blood vessel damages occurred in all cases. All final screw positions were validated by CT.

Conclusion

The five-step remedial method proved to be an effective supplementary method for transpedicular screw placement to treat patients with severe spinal deformities. The key points include a detailed preoperative plan, a meticulous hand drilling sensation, and an experienced probing technique for screw tract.