颅颈交界区后路螺钉内固定

目的 报告C2椎弓根螺钉结合C1侧块或枕骨螺钉用于颅颈交界区后路内固定的解剖研究及临床应用结果.方法 福尔马林固定的头颈标本4个,根据解剖标志分别植入C2椎弓根及C1侧块螺钉,然后行CT扫描及重建,观察螺钉位置.2004年5月至2007年1月,利用C2椎弓根一C1侧块/枕骨螺钉内同定9例病人,男4例,女5例,年龄12～68岁,平均38岁;各种原因引起的C1～C2半脱位6例,因颅底凹陷经口腔齿状突切除后1例,斜坡脊索瘤经口腔切除手术前2例;采用C2椎弓根-C1侧块螺钉技术4例,C2椎弓根一枕骨螺钉技术5例,手术后均行CT扫描观察螺钉位置.结果 手术中直接显露C2椎弓根内上缘,并以此确立进钉方向,在椎弓根峡部后缘确定进钉点,可保证C2椎弓根螺钉的安全植入;直接显露C1侧块后正中确立进钉点,可避免螺钉植入过程中的椎动脉损伤.9例病人中,手术后CT复查有2例病人两颗螺钉穿破骨皮质,但末造成血管及神经的压迫,其余螺钉位置均较好;随访4-32个月,1例临床症状较术前无变化,其余8例均改善.结论 C2椎弓根-C1侧块/枕骨螺钉技术可安全有效地用于颅颈交界区内固定.     

Modified C1 lateral mass screw insertion using a high entry point to avoid postoperative occipital neuralgia

For the past decade, a screw–rod construct has been used commonly to stabilize the atlantoaxial joint, but the insertion of the screw through the C1 lateral mass (LM) can cause several complications. We evaluated whether using a higher screw entry point for C1 lateral mass (LM) fixation than in the standard procedure could prevent screw-induced occipital neuralgia. We enrolled 12 consecutive patients who underwent bilateral C1 LM fixation, with the modified screw insertion point at the junction of the C1 posterior arch and the midpoint of the posterior inferior portion of the C1 LM. We measured postoperative clinical and radiological parameters and recorded intraoperative complications, postoperative neurological deficits and the occurrence of occipital neuralgia. Postoperative plain radiographs were used to check for malpositioning of the screw or failure of the construct. Four patients underwent atlantoaxial stabilization for a transverse ligament injury or a C1 or C2 fracture, six patients for os odontoideum, and two patients for C2 metastasis. No patient experienced vertebral artery injury or cerebrospinal fluid leak, and all had minimal blood loss. No patient suffered significant occipital neuralgia, although one patient developed mild, transient unilateral neuralgia. There was also no radiographic evidence of construct failure. Twenty screws were positioned correctly through the intended entry points, but three screws were placed inferiorly (that is, below the arch), and one screw was inserted too medially. When performing C1–C2 fixation using the standard (Harms) construct, surgeons should be aware of the possible development of occipital neuralgia. A higher entry point may prevent this complication; therefore, we recommend that the screw should be inserted into the arch of C1 if it can be accommodated.     

Hybrid lateral mass screw sublaminar wire construct: A salvage technique for posterior cervical fixation in pediatric spine surgery

We present a novel salvage technique for pediatric subaxial cervical spine fusion in which lateral mass screw fixation was not possible due to anatomic constraints. The case presentation details a 4-year-old patient with C5–C6 flexion/distraction injury with bilateral jumped facets. Posterior cervical fixation was attempted; however, lateral mass fracture occurred during placement of screws. Using a wire-screw construct, an attempt was made to provide stable fixation. The patient was followed post-operatively for assessment of outcomes. After the patient had progressive kyphosis following initial closed reduction and external orthosis, internal reduction with fusion/fixation was performed. Lateral mass fracture occurred during placement of lateral mass screws. After placement of a sub-laminar wire-lateral mass screw construct, intra-operative evaluation determined stability. Post-operatively, the procedure resulted in stable fixation with evidence of bony fusion on follow-up. Pediatric subaxial cervical spine instrumentation provides rigid fixation however is technically difficult due to anatomic and instrumentation related constraints. In the presented patient, the wire-screw construct resulted in stable fixation and bony fusion on follow-up. A modified sublaminar wire-lateral mass screw construct is an example of a salvage technique that provides immediate stability in the event of instrumentation related lateral mass fracture.     

Feasibility and limitations of C1 lateral mass screw placement in patients of atlas assimilation

Background

C1 lateral mass is a common place for screw fixation in normal anatomy; whereas there is no research about whether screw placement is suitable in patients of C1 assimilation (C1A).

Objective

To study the feasibility and limitations of C1 lateral mass screw placement in patients with C1A.

Patients and methods

From April 2008 to March 2009, C1 lateral mass of 17 C1A patients with atlantoaxial instability (AAI) or dislocation (AAD) was observed and measured using CT reconstruction; and factors determining C1 lateral mass screw placement were studied before and during the operation.

Results

A screw of 3.5 mm in diameter could be virtually inserted in 31 C1 lateral masses of total 17 C1A patients with maximal length of the screw 18.1 ± 2.7 mm; but the entry point of screw had to be modified in the posterior part of inferior facet of C1 instead of posterior middle wall of C1 lateral mass. Clinically, abnormal course of vertebral artery in 6 of 30 (20%) and abundance of venous plexi prevented the proper exposure of C1 lateral mass and screw placement. Hypoglossal canal also had potential risk of injury during screw placement.

Conclusion

In patients of C1A, when C1 lateral mass screw placement is programmed, factors limit its use should be well studied, and CT angiography is essential.     

Posterior percutaneous transarticular stand-alone screw instrumentation of C1-C2 with endoscopic assistance: A report of two cases

We present two cases of minimally invasive posterior transarticular screw fixation of C1-C2. The points for screw insertion were visualized by endoscopy via the instrumental port. A patient with a type III odontoid fracture with subluxation underwent a minimally invasive posterior stand-alone transarticular screw fixation. Despite the application of compression screws, for technical reasons, only minimal compression on the anterior third of the C1-C2 lateral joint was achieved. However, complete fracture fusion was achieved with stable fibrous C1-C2 fusion 2.5 years postoperatively. A second patient with a chronic type II odontoid fracture underwent percutaneous C1-C2 fixation by the same method. After 2 years, fracture fusion and C1-C2 lateral mass ankylosis were achieved. The use of a tubular retractor and endoscopy in stand-alone screw fixation of C1-C2 allows direct visualization of the screw entry point and decreases surgical trauma. This procedure might be an alternative to other methods of transarticular instrumentation.     

C7 Posterior Fixation Using Intralaminar Screws : Early Clinical and Radiographic Outcome

Objective

The use of segmental instrumentation technique using pedicle screw has been increasingly popular in recent years owing to its biomechanical stability. Recently, intralaminar screws have been used as a potentially safer alternative to traditional fusion constructs involving fixation of C2 and the cervicothoracic junction including C7. However, to date, there have been few clinical series of C7 laminar screw fixation in the literature. Thus, the purpose of this study is to report our clinical experiences using C7 laminar screw and the early clinical outcome of this rather new fixation technique.

Methods

Thirteen patients underwent C7 intralaminar fixation to treat lesions from trauma or degenerative disease. Seventeen intralaminar screws were placed at C7. The patients were assessed both clinically and radiographically with postoperative computed tomographic scans.

Results

There was no violation of the screw into the spinal canal during the procedure and no neurological worsening or vascular injury from screw placement. The mean clinical and radiographic follow up was about 19 months, at which time there were no cases of screw pull-out, screw fracture or non-union. Complications included two cases of dorsal breech of intralaminar screw and one case of postoperative infection.

Conclusion

Intralaminar screws can be potentially safe alternative technique for C7 fixation. Even though this technique cannot be used in the cases of C7 laminar fracture, large margin of safety and the ease of screw placement create a niche for this technique in the armamentarium of spine surgeons.     

Atlantoaxial fixation: overview of all techniques

Over the past century, steady advances have been made in fixating an unstable atlantoaxial complex. Current options for fixation of the atlantoaxial complex include posterior clamps, posterior wiring techniques, C1-C2 transarticular screw fixation, posterior C1 lateral mass screw with C2 pars or pedicle screw fixation, and anterior transoral C1 lateral mass to C2 vertebral body fixation.     

Modified C1 lateral mass screw insertion using a threaded K-wire. A technical note

Instrumented fixation of the C1-C2 motion segment is a standard surgical technique to stabilise that spinal segment. Instability at C1-C2 can arise from a number of conditions. Fixation of the C1 lateral mass usually involves dissection and exposure of the C2 nerve root and the posterior wall of the C2 lateral mass which can result in significant bleeding from the venous plexus. Whilst image guidance is increasing in accessibility, there are few public hospitals in Australia that have access to this technology. The authors describe their technique for insertion of a C1 lateral mass screw over a threaded K-wire to avoid extensive dissection of the C2 nerve root, reducing the risk of significant haemorrhage from the epidural venous plexus during the procedure. A retrospective analysis was undertaken on 18 consecutive patients who underwent C1-C2 instrumented fixation using this technique. Indications for C1-C2 instrumented fixation included traumatic injury (10 patients), failure of non-operative management of odontoid fractures (5 patients), pathological fractures of C2 (2 patients) and inflammatory conditions (1 patient). All patients underwent successful C1-C2 stabilisation using this technique. Blood loss did not exceed 400mls in any patient. There were no vertebral artery injuries and no patient experienced a neurological deterioration. The authors propose that their technique for insertion of a C1 lateral mass screw over a threaded K-wire is safe and effective with a low risk of neurological or vertebral artery injury. The technique may be considered as a slight modification of the Harm’s procedure to reduce disturbance of the adjacent venous plexus and thereby reduction in intraoperative bleeding and operative time.     

Clinical and radiological Comparison of treatment of atlantoaxial instability by posterior C1–C2 transarticular screw fixation or C1 lateral mass-C2 pedicle screw fixation

We compared the clinical and radiological results of posterior atlantoaxial fixation surgery using transarticular screws to those using a polyaxial screw–rod system in 55 patients with symptomatic atlantoaxial instability. Patients underwent posterior C1–C2 fixation: 28 patients (group 1) underwent C1–C2 transarticular screw fixation and 27 patients (group 2) underwent C1 lateral mass–C2 pedicle screw fixation. Patients were followed-up for at least 24 months. The clinical and radiological results were evaluated in the early postoperative period and at 3, 6, 12 and 24 months after surgery. Long-term postoperative stability and bone fusion were examined. After surgery, 93% of patients in group 1 and 96% of patients in group 2 were free of neck pain. The solid fusion rates were 82% for group 1 patients and 96% for group 2 patients at 12 months (p < 0.092). In group 1, three patients showed fibrous union. Four patients had hardware failure due to a screw malposition (one in group 1) and pseudoarthrodesis (two in group 1 and one in group 2). One patient in group 1 had cerebrospinal fluid leakage. One patient in group 2 had occipital neuralgia. One vertebral artery injury occurred during the screw placement in group 1 and another in group 2 during the muscle dissection. C1–C2 transarticular screw fixation and C1 lateral mass–C2 pedicle screw fixation both produced excellent results for stabilization of the atlantoaxial complex, but the radiological outcome tended to be superior in C1 lateral mass–C2 pedicle screw fixation.     

Fusions at the craniovertebral junction

INTRODUCTION: The surgical management of craniovertebral junction instability in pediatric patients has unique challenges. While the indications for internal fixation in children are similar to those of adults, the data concerning techniques, complications, and outcomes of spinal instrumentation comes from experience with adult patients. Diminutive osseous and ligamentous structures and anatomical variations associated with syndromic craniovertebral abnormalities frequently complicates the approaches and limits the use of internal fixation in children. Cervical arthrodesis in the pediatric age group has the potential for limiting growth potential and causing secondary deformity. Recent advances in image analysis have enabled preoperative planning which is critical to evaluate the size of instrumentation and its relation to the patient's anatomy. Newer techniques have recently evolved and have been incorporated in the management of pediatric patients with requirement for craniocervical stabilization. MATERIALS AND METHODS: Over 750 craniovertebral junction fusions have been reviewed in children. The indications for atlantoaxial arthrodesis were: (a) absent odontoid process, dystopic os odontoideum, absent posterior arch of C1; (b) Morquio's syndrome, Goldenhar's syndrome, Conradi's syndrome, and spondyloepiphyseal dysplasia. The acquired abnormalities of trauma, postinfectious instability, and Down's syndrome completed the indication in children. The indications for occipitocervical fusion were: (a) anterior and posterior bifid C1 arches with instability, absent occipital condyles; b) severe reducible basilar invagination, unstable dystopic os odontoideum, and unilateral atlas assimilation; (c) acquired phenomenon with traumatic occipitocervical dislocation, complex craniovertebral junction fractures of C1 and C2, after transoral craniovertebral junction decompression, cranial settling in Down's syndrome and inflammatory disease such as Grisel's syndrome. Instability was seen in children with clivus chordoma and osteoblastoma. Atlantoaxial fusions were performed mainly with interlaminar rib graft fusion and more recently with the transarticular screw fixation in the older patient. In the teenager, lateral mass screws at C1 and rod fixation were made; C2 pars interarticular screw fixation and C2 pedicle screw fixation. A C2 translaminar screw fixation is described. Occipitocervical fusions were made utilizing rib grafts below the age of 6. A contoured loop fixation was made in children above the age of 7, and recently, rod and screw fixation was also utilized. RESULTS: Abnormal cervical spine growth was not seen in children who underwent craniocervical stabilization below the age of 5. The authors have reserved rigid instrumentation for children above the age of 10 years and dependent on the anatomy.     

Screw fixation of craniocervical junction

In recent years an increase has been observed of the use of screw techniques for the fixation of the craniocervical junction. For clinical use two techniques have been introduced: (1) transarticular screw fixation, and (2) transpedicular screw fixation. In the former the screw is inserted through the C2 lateral mass, the fissure of the C1-C2 joint, and the C1 lateral mass. (2) in the latter the screw is inserted into the C2 pedicle and anchored in C2 vertebral body. Transarticular or pedicle screws can be easily connected to longitudinal elements such as rods or plates, and combined with lateral mass screws of the remaining cervical vertebrae or occipital screws. In comparison to sublaminar wiring or interlaminar clamping the screw techniques: (a) strengthen the stiffness of the construct and speed up fusion, (b) allow fixation in the absence or deficiency of laminae as a result of trauma or laminectomy, and (c) can selectively include only the affected segments. Increased construct stiffness is due to deep anchorage of the screw in bone providing thus a solid grip on the vertebra. Both techniques require preoperative assessment of the course of the vertebral artery using imaging methods. In about 18% of cases abnormal course of the artery precludes screw use. Pedicle screw insertion requires direct control of the medial and superior walls of C2 pedicle with dissector introduced into the vertebral canal, which requires removal of the atlantoaxial ligament. Additional control can be achieved with lateral fluoroscopy. The entry point for transarticular screw is on the lateral mass of the odontoid 2-3 mm laterally to the medial margin of C2 facet and 2-3 mm above the C1/C2 articular fissure. The screw trajectory is 0-10 degrees in horizontal plane and towards the anterior C1 tuberculum in sagittal plane.     

Troublesome Occipital Neuralgia Developed by C1-C2 Harms Construct

Recently, Harms and Melcher modified Goel''s approach, the C1 lateral mass and C2 pedicle screw fixation, and the new technique is currently in favor among neurosurgeons. Comparing to the advantages of Harms construct, the disadvantages were not extensively investigated. We experienced a patient with severe occipital pain developed after the C1 lateral mass screw placement for the traumatic atlantoaxial instability. We reviewed literatures about Harms construct with focus on the occipital neuralgia as a postoperative complication and suggest here technical tips to avoid the troublesome pain.     

颈椎后路螺钉-钛棒(板)内固定技术:初步临床报告

目的 报告利用螺钉-钛棒（板）固定技术治疗各种原因引起的颈椎不稳的初步临床结果。方法 作者1年来行颈椎后路螺钉-钛棒（板）技术内固定9例，其中齿突样骨引起的C1～C2不稳2例，手术后进行性颈椎后凸2例，颈椎管狭窄2例，C3-C4滑脱1例，C6～C7外伤滑脱2例。分别采用C1侧块、C2椎弓根螺钉、C3～C5侧块螺钉、C2-T2椎弓根螺钉植入技术，然后连接钛棒或钛板完成固定。9例病人共植入螺钉59枚。结果 所有病人在1周内带外支架进行活动，除1例因拒绝治疗死亡外，其余病人在1个月及1年后复查均未见内固定物移位。结论 颈椎后路螺钉-钛棒（板）固定为安全可靠的技术，可以术后即刻获得牢固内固定，为下一步治疗创造有利条件。     

三种置钉方法在下颈椎经椎弓根螺钉置入过程中的比较

背景：目前各种下颈椎椎弓根置钉方法的准确率报道不一,特别是国内常用的椎板部分切除置钉法、Abumi法、管道疏通法缺乏比较。 目的：探讨下颈椎(C3~7)经椎弓根螺钉内固定的可行性,比较椎板部分切除置钉法、Abumi法、管道疏通法在置钉满意率、出血量、置钉时间、并发症等方面的差异。 方法：选择60例需颈后路经椎弓根螺钉内固定治疗的下颈椎疾患病例,随机分成3组,各置入椎弓根螺钉80枚,分别采用椎板部分切除置钉法、Abumi法及管道疏通法。术中计算各方法置钉时间、出血量;出院前观察置钉满意率及在颈椎椎弓根四壁损伤例数的构成比;比较C3~7每一节段的椎弓根外侧壁损伤发生率。 结果与结论：椎板部分切除组、Abumi组及管道疏通组置钉时间依次递减(P < 0.05),置钉满意率依次递增(P < 0.05)。3组间置钉出血量及颈椎椎弓根四壁损伤例数的构成比差异无显著性意义(P > 0.05),椎弓根损伤好发生于外壁。C4、C5节段外壁损伤发生率明显高于C3、C6、C7。提示管道疏通法在经颈后路椎弓根螺钉内固定常规置钉法中优势明显。     

C1-C2 transarticular screw fixation for treatment of C1-C2 instability

C1-C2 instability has traditionally been treated by C1-C2 posterior wiring and bone grafting. However, this technique has an incidence of non-union which may exceed 10%. Transarticular screw fixation has developed as a technique of providing increased strength of fixation of C1-C2 arthrodesis, while at the same time avoiding the need for postoperative halo bracing and avoiding the risk of neurological injury associated with the passage of sublaminar wires. We present a retrospective review of 12 patients with C1-C2 instability treated by C1-C2 transarticular screw fixation. Eight patients underwent this procedure as primary treatment, and 4 after a failed Gallie fusion. Five patients had a cruciate ligament rupture, 5 had an odontoid process fracture, 1 had os odontoideum, and 1 had rheumatoid instability. There was no surgical morbidity or mortality and, at a mean follow up of 12.1 +/- 3 months (range 8-14 months), all patients had achieved solid fusion, and all neurological symptoms referable to the instability had resolved. C1-C2 transarticular screw fixation has been shown to be safe and effective and has a number of advantages when compared to traditional posterior wiring techniques. We recommend that this technique be considered as a primary treatment of C1-C2 instability.     

Clinical Experiences and Usefulness of Cervical Posterior Stabilization with Polyaxial Screw-Rod System

Objective

The objective of this study is to investigate the safety, surgical efficacy, and advantages of a polyaxial screw-rod system for posterior occipitocervicothoracic arthrodesis.

Methods

Charts and radiographs of 32 patients who underwent posterior cervical fixation between October 2004 and February 2006 were retrospectively reviewed. Posterior cervical polyaxial screw-rod fixation was applied on the cervical spine and/or upper thoracic spine. The surgical indication was fracture or dislocation in 18, C1-2 ligamentous injury with trauma in 5, atlantoaxial instability by rheumatoid arthritis (RA) or diffuse idiopathic skeletal hyperostosis (DISH) in 4, cervical spondylosis with myelopathy in 4, and spinal metastatic tumor in 1. The patients were followed up and evaluated based on their clinical status and radiographs at 1, 3, 6 months and 1 year after surgery.

Results

A total of 189 screws were implanted in 32 patients. Fixation was carried out over an average of 3.3 spinal segment (range, 2 to 7). The mean follow-up interval was 20.2 months. This system allowed for screw placement in the occiput, C1 lateral mass, C2 pars, C3-7 lateral masses, as well as the lower cervical and upper thoracic pedicles. Satisfactory bony fusion and reduction were achieved and confirmed in postoperative flexion-extension lateral radiographs and computed tomography (CT) scans in all cases. Revision surgery was required in two cases due to deep wound infection. One case needed a skin graft due to necrotic change. There was one case of kyphotic change due to adjacent segmental degeneration. There were no other complications, such as cord or vertebral artery injury, cerebrospinal fluid leak, screw malposition or back-out, or implant failure, and there were no cases of postoperative radiculopathy due to foraminal stenosis.

Conclusion

Posterior cervical stabilization with a polyaxial screw-rod system is a safe and reliable technique that appears to offer several advantages over existing methods. Further biomechanical testings and clinical experiences are needed in order to determine the true benefits of this procedure.     

Fixating techniques of craniocervical junction: selection criteria

Adequate choice of fixation technique at craniocervical junction depends on many factors: anatomical conditions at fusion site (e.g. anterior dislocations of the odontoid and rupture of the transverse ligament are contraindications for direct odontoid screw fixation. Sublaminar wiring and interlaminar clamps are useless in case of deficiency of posterior bony elements of C1 and C2 whether a result of laminectomy or destruction), bone quality (osteopenic bone is contraindication for screw techniques either transarticular or transpedicular). Enclosing of occipital bone into instrumentation may be difficult in wire and clamping techniques. In contrast screw techniques allow for easy grip the occipital bone. Screw techniques seem ideal in cases requiring enclosing of the occipital bone. The fusion rate at C1/C2 level seems independent of fixation techniques. When supplemented with external immobilization even biomechanically inferior wiring or interlaminar clamping provide nearly 100 rate of fusion. Screw techniques are technically demanding but they seem the method of choice when occipital bone is to be enclosed in instrumentation.     

Anatomic Feasibility of Posterior Cervical Pedicle Screw Placement in Children: Computerized Tomographic Analysis of Children Under 10 Years Old

ObjectiveTo evaluate the anatomical feasibility of 3.5 mm screw into the cervical spine in the pediatric population and to establish useful guidelines for their placement.MethodsA total of 37 cervical spine computerized tomography scans (24 boys and 13 girls) were included in this study. All patients were younger than 10 years of age at the time of evaluation for the period of 2007-2011.ResultsFor the C1 screw placement, entry point height (EPH) was the most restrictive factor (47.3% patients were larger than 3.5 mm). All C2 lamina had a height larger than 3.5 mm and 68.8% (51/74) of C2 lamina had a width thicker than 3.5 mm. For C2 pedicle width, 55.4% (41/74) of cases were larger than 3.5 mm, while 58.1% (43/74) of pedicle heights were larger than 3.5 mm. For pedicle width of subaxial spine, 75.7% (C3), 73% (C4), 82.4% (C5), 89.2% (C6), and 98.1% (C7, 1/54) were greater than 3.5 mm. Mean lamina width of subaxial cervical spine was 3.1 (C3), 2.7 (C4), 2.9 (C5), 3.8 (C6), and 4.0 mm (C7), respectively. Only 34.6% (127/370) of subaxial (C3-7) lamina thickness were greater than 3.5 mm. Mean length of lateral mass for the lateral mass screw placement was 9.28 (C3), 9.08 (C4), 8.81 (C5), 8.98 (C6), and 10.38 mm (C7).ConclusionC1 lateral mass fixation could be limited by the morphometrics of lateral mass height. C2 trans-lamina approach is preferable to C2 pedicle screw fixation. In subaxial spines, pedicle screw placement was preferable to trans-lamina screw placement, except at C7.