Cervical stabilization by plate and bone fusion

Anterior stabilization with combined plate and bone fusion was performed after neural decompression on ten patients for spondylotic cervical myelopathy, and for radiculopathy or trauma in three patients. Medial corpectomy was performed at one to four levels. Iliac crest or fibular bone grafts were secured by plates anchored to the graft and adjacent vertebral bodies. All patients were placed in Minerva braces postoperatively. There was successful fusion in all cases, and no graft dislodgement or kyphosis. Early initiation of rehabilitation was achieved. Morbidity occurred in patients with severe spondylotic cervical myelopathy. This include respiratory depression requiring reintubation in 2/13 procedures, dysphagia (2/13) from loosening of the screws or prominent hardware and graft, and screw loosening (2/13). Neurological improvement was present in 85% (11/13) of patients. There was no deterioration of neurological function in any case. We conclude from this early follow-up that anterior bone fusion with supplemental plates provides effective stabilization for the unstable cervical spine. Greater morbidity risk exists in patients with severe spondylotic cervical myelopathy and spastic quadriparesis who required multilevel medial corpectomies and fusion.     

Esophageal perforation after anterior cervical plate fixation: a report of two cases.

We report two cases of esophageal complications due to migration of screws after anterior plate fixation of the cervical spine. Close observation for screw back out is needed, particularly in those patients with associated neurologic deficits or osteoporosis.     

Placement of anterior cervical instrumentation without intraoperative radiography.

Adequate fixation with several commonly used anterior cervical plate systems requires that the screws penetrate both the anterior and posterior cortices of the vertebral bodies. This report emphasizes the shortcomings of plain film and fluoroscopic examinations in confirming screw position through the posterior vertebral cortex in three patients with lower cervical trauma or tumor. These cases and radiographs of isolated vertebrae from the cervicothoracic region demonstrate the inadequacy of plain film/fluoroscopy for determination of the position of anterior cervical plate screws in relation to the posterior cortex. Only axial images such as those obtained with computed tomography are able to show the exact relationship of the screws to the posterior cortical curvature in C7 and T1.     

Anterior locking screw plate fixation for cervical spondylosis

Thirty consecutive patients with significant cervical spondylotic myelopathy or radiculopathy were treated with anterior decompression, autologous iliac crest graft, and titanium hollow screw plate (THSP). Eight patients had 1 previous surgery, and 1 patient had 2 previous surgeries. Satisfactory fixation was achieved intraoperatively in all instances. At time of final follow-up, graft incorporation was noted in all instances. There were 4 complications: 2 superficial infections, treated nonoperatively; 1 case of dysphagia, which resolved; and 1 case of spasmodic torticollis, which resolved. The THSP system allowed immediate stabilization of the involved cervical levels and facilitated reliable fusion.     

Spinal Instrumentation With A Low Complication Rate

Background

Spinal instrumentation has become an increasing part of the armamentarium of neurosurgery and neurosurgical training. For noncontroversial indications for spine fusion the arthrodesis rate seems to be better. For both noncontroversial and controversial indications, the reported complication rate with spinal instrumentation tends to be greater than that with noninstrumented spine surgeries. These reported complications include a 2–3% neurologic injury rate, 3–45% reoperation rate for implant failure, and infection rates of 5–10%. Therefore, we report on 299 cases that have undergone spinal instrumentation placed exclusively by neurosurgeons with a very low complication rate.

Methods

Two hundred ninety-nine consecutive spinal instrumentation cases performed exclusively by neurosurgeons at Indiana University Medical Center were analyzed for complications related to spinal instrumentation. The spinal instrumentation placed consisted of 195 anterior cervical locking plates, 22 cases of posterior cervical instrumentation, 9 cases of combined anterior locking plates with posterior cervical instrumentation, 14 anterior thoraco-lumbar plates, 51 posterior thoraco-lumbar instrumentation cases, and 8 combined anterior/posterior thoraco-lumbar instrumentation cases.

Results

The mean follow-up is 40 months (6–95). There was one perioperative death unrelated to the spinal instrumentation. There were no neurologic injuries and there has been no hardware infection to date. There were two dural tears, three superficial wound infections, and three minor wound breakdowns successfully treated. Hardware complications included three cervical plate/screw extrusions reoperated, one cervical plate fracture reoperated, one posterior cervical screw backout not reoperated, one case of broken pedicle screws not reoperated, one vertebral body failure not reoperated, and one posterior rod case reoperated for excessive rod length and protrusion. The overall complication rate attributable to placement of spinal instrumentation was 10/299 (3%) with a reoperation rate of 2%. The arthrodesis rate was 298/299 (99%).

Conclusion

The complication rate for using spinal instrumentation can be less than previously reported. Lessons learned and discussed should reduce the rate even more. Spinal instrumentation is a safe and useful adjunct to fusion in treating degenerative, traumatic, infectious, and neoplastic diseases of the spine.     

颈椎前路钛板在颈椎前路减压融合术中的应用

目的 探讨前路钛板在手术治疗颈椎创伤、脊髓型颈椎病、颈椎肿瘤等病变中的作用。方法 应用前路钛板治疗颈椎创伤与疾病22例，其中脊髓型颈椎病(包括颈椎间盘突出)13例，颈椎骨折5例，后纵韧带骨化症2例，颈椎肿瘤2例。结果 本组22例均获随访，随访时间5个月～3年5个月，平均1.5年，21例植骨块与上下椎体融合(95.5％)，1例不融合(4.5％)。无钛板松动断裂、移位，亦无植骨块脱出压迫食道。术后除1例脊柱骨折脱位脊髓损伤症状无恢复，其它均有不同程度的恢复，优良率86.1％。结论 颈椎前路钛板内固定具有显的优越性，可起到术后即刻稳定、防止植骨块移位、术后无需行石膏外固定、明显提高植骨融合率等作用。但应严格掌握手术指征和操作技术，以减少或避免并发症发生。     

Minimally invasive lateral mass plating in the treatment of posterior cervical trauma: surgical technique

OBJECTIVE: The technique of lateral mass fixation restores the posterior tension band and provides effective stabilization in patients with many types of traumatic injuries. However, postoperative wound pain is not uncommon. The objective of this work is to describe a modified technique of minimally invasive lateral mass plating for cervical spine trauma. METHODS: Patient 1 was a 64-year-old woman who had been in a motor vehicle accident and sustained bilateral C5-C6 facet dislocation with posterior C5-C6 distraction. She was otherwise neurologically intact, and attempts at closed reduction were not successful. Patient 2 was a 16-year-old girl who had also been in a motor vehicle accident but had an incomplete spinal cord injury. She had an unstable burst fracture of C7 with posterior C5-C6 distraction. Both patients underwent anterior cervical fusion followed by staged minimally invasive posterior fusion with good results. A dilator tubular retractor system (METRX) was used to access the bilateral lateral masses through a small midline incision under fluoroscopic guidance. Lateral mass screws were then placed by using a modified Magerl technique, securing two-hole plates on each side onto the lateral masses, performed through the METRX system. We also successfully performed four-level lateral mass plating in a cadaveric cervical spine using a 2-cm skin incision. CONCLUSIONS: We describe successful placement of lateral mass screw and plate constructs with the use of a minimally invasive approach by means of a tubular dilator retractor system. This approach preserves the integrity of the muscles and ligaments that maintain the posterior tension band of the cervical spine.     

Irreducible dislocations of the cervical spine with a prolapsed disc: preliminary results from a treatment technique

STUDY DESIGN: The preliminary results from a treatment technique for irreducible dislocations of the cervical spine with prolapsed disk are reported. OBJECTIVE: To report the success of a technique for grafting and instrumentation of the anterior cervical spine before reduction. This technique is useful in cervical fracture-dislocations irreducible through the anterior approach that must be approached first from the front because of a prolapsed disc. SUMMARY OF BACKGROUND DATA: In the treatment of cervical facet dislocations, a third anterior procedure often is necessary to accomplish the anterior instrumentation and fusion. The reported technique describes a method that eliminates this third procedure by using a cervical buttress plate. METHODS: Between August of 1996 and October 1998, four patients had dislocation of the cervical spine with a prolapsed disc that could not be reduced using the anterior approach. After discectomy and endplate preparation, a tricortical bone graft was harvested from the iliac crest, placed in the interspace, and held with a buttress plate screwed in two places into the superior vertebral body. The anterior wound then was closed. The posterior elements were exposed and the facets reduced by flexing the neck and posteriorly translating the superior segment. Fluoroscopy was used during the reduction to ensure that the graft was pulled into the interspace, that the screws in the buttress plate did not pull out of the superior vertebral body, and that the reduced graft did not impinge on the spinal cord. A posterior fusion was performed and the posterior wound closed. RESULTS: All the patients had consolidation of both anterior and posterior fusions. No cases of instrument failure occurred, either anteriorly or posteriorly. No cases of neurologic deterioration occurred, and no complications were attributable to the use of this technique. CONCLUSION: The reported technique was used successfully in the treatment of four patients with irreducible dislocations of the cervical spine.     

颈椎带锁钢板在单节段颈前路融合术中的应用价值

目的探讨颈椎带锁钢板在单节段颈前路融合术中的应用价值。方法对 50例颈椎疾患患者施行前路减压、自体髂骨植骨及 AO颈椎前路带锁钢板内固定术。术后随访观察植骨融合率、椎间高度维持情况及有无内置物并发症。结果 46例获得随访,平均随访时间 26个月。 45例获得牢固骨性融合,融合率为 97.8％;椎间高度维持良好;未发生钢板螺钉松动、滑脱或断裂等内置物并发症。结论颈椎前路带锁钢板应用于单节段颈前路融合术可显著提高植骨融合率,并有效维持椎间高度,避免了由于椎间塌陷带来的继发性神经功能损害。只要掌握手术适应证,遵循手术操作原则,内置物并发症一般是可以避免的,因此有着良好的应用前景。     

Biomechanical evaluation of a newly developed monocortical expansion screw for use in anterior internal fixation of the cervical spine. In vitro comparison with two established internal fixation systems

STUDY DESIGN: The primary biomechanical stability of anterior internal fixation of the cervical spine obtained with a new monocortical expansion screw in vitro was evaluated. OBJECTIVES: To determine whether the anterior internal fixation of the spine obtained with the new monocortical expansion screw provides biomechanical stability comparable with that obtained with bicortical fixation. SUMMARY OF BACKGROUND DATA: The anterior plate instrumentation used with bicortical screw fixation in the cervical spine provides a primary stability superior to that associated with monocortical screw fixation. However, bicortical screws have the potential to perforate the posterior cortex. Therefore, monocortical instrumentation systems were developed, but without the biomechanical stability associated with bicortical systems. A new expansion screw for monocortical fixation was developed to improve biomechanical stability of monocortical systems. METHODS: Three different internal fixation systems were compared in this study: 1) H-plate with AO 3.5-mm bicortical screws, 2) cervical spine locking plate with monocortical screws, and 3) H-plate with the new monocortical expansion screws. Eight fresh human cadaver spine segments from C4 to C7 were tested in flexion-extension, axial rotation, and lateral bending using pure moments of +/- 2.5 Nm without axial preload. Five conditions were investigated consecutively: 1) intact spine; 2) uninstrumented spine with the segment C5-C6 destabilized; 3-5) instrumentation of the segment C5-C6 with the three implants mentioned above after removal of the disc and insertion of an interbody spacer. RESULTS: Between bicortical and monocortical expansion screw H-plate fixation, no significant differences were observed in all load cases concerning range of motion and neutral zone. The neutral zone and range of motion were significantly larger for the cervical spine locking plate than for bicortical and monocortical expansion screw fixation in all load cases, except neutral zone for axial rotation versus bicortical screw fixation. The instrumented cases only had a significantly lower range of motion and neutral zone than the intact cases in extension-flexion, whereas for lateral bending and axial rotation no significant differences could be observed. Because the experimental design precluded any cyclic testing, the data represent only the primary stability of the implants. CONCLUSIONS: In anterior instrumentation of the cervical spine using a H-plate, the new monocortical expansion screw provides the same biomechanical stability as the bicortical 3.5-mm AO screw and a significantly better biomechanical stability than the cervical spine locking plate. Therefore, the expansion screw may be an alternative to the bicortical fixation and does not involve the risk of penetration of the posterior vertebral body cortex.     

Surgical stabilization of the cervical spine. A comparative analysis of anterior and posterior spine fusions

Two hundred twenty-two cervical spine stabilization procedures in 212 patients are reviewed. In 114 posterior cervical fusions, 88 anterior fusions, and ten combined procedures, no deaths occurred. Surgical complication rates were similar, but more severe complications were noted with anterior cervical fusions, including tracheoesophageal problems and transient neurologic loss. Six cases of graft dislodgement requiring reoperation also occurred. In long-term follow-up evaluations, 36 anterior fusion patients developed progressive kyphotic deformity averaging 22 degrees between surgery and the time solid fusion was obtained. Degenerative changes above and below the fusion mass were detected in 36 of 59 patients treated by anterior surgery. Posterior cervical fusion patients were noted to have no significant late change in alignment, and degenerative changes were infrequent. However, 73 of 98 patients had significant extension of fusion mass beyond the originally intended levels of stabilization. Because anterior cervical spine fusion was associated with significant complications of graft dislodgement and tracheoesophageal trauma, as well as postsurgical progressive deformity, the authors recommend posterior wiring and fusion as the procedure of choice to treat cervical spine instability and permit halo-free postsurgical rehabilitation. When anterior neural decompression and fusion is necessary, concomitant posterior wiring and fusion or halo vest immobilization may be necessary to maintain reduction and prevent kyphotic angulation, because posterior ligamentous disruption is not always grossly evident on radiographic examination.     

下颈椎经关节螺钉联合侧块或椎弓根螺钉固定的效果

目的 探讨在下颈椎经颈后正中入路应用经关节螺钉联合侧块螺钉或椎弓根螺钉行内固定治疗的固定效果.方法 2003年2月至2007年10月,对22例患者通过后路应用经关节螺钉联合侧块螺钉或椎弓根螺钉行内固定治疗,男14例,女8例;年龄24～73岁,平均43岁.其中下颈椎创伤性骨折脱位13例,颈椎后纵韧带骨化症4例,颈椎管狭窄伴Ⅱ型齿突骨折1例,颈椎间盘突出伴椎管狭窄4例.结果 共置入经关节螺钉45枚,其中C4,5 2枚,C5,639枚,C6,74枚;共置入侧块螺钉12枚,C3、C4各6枚;共置入椎弓根螺钉41枚,其中C24枚,C32枚,C46枚,C721枚,T18枚.术中所有螺钉均成功置入,未出现椎动脉、神经根和脊髓损伤等置钉相关并发症.22例患者均获随访,随访时间10个月～3年8个月,平均17个月.植骨融合时间3～5个月,平均3.5个月.术后发现1例患者的2枚经关节螺钉松动,部分脱出.经加强颈托制动,术后4个月获得融合.结论 通过后路固定下颈椎时,采用经关节螺钉联合侧块螺钉或椎弓根螺钉固定,均可取得较好的固定效果.     

Biomechanical comparison of anterior cervical spine locked and unlocked plate-fixation systems

Three different anterior plate-fixation systems are available for the stabilisation of the cervical spine: (1) the cervical spine locking plate (CSLP), (2) dynamic plates allowing vertical migration of the fixation screws, and (3) various types of plates that are secured with either monocortical or bicortical unlocked screws. Unicortical screw purchase does not involve the risk of posterior cortex penetration and possible injuries to the spinal cord. The development of locking plates with unicortical screw-fixation and intrinsic stability of the screw–plate interface, via an angle-stabilised connection, was an attempt to increase the stability of unicortical screw-fixation systems. The aim of the study was to compare the biomechanical properties of a non-locking, anterior-plate system with 4.5 mm screw fixation and a locking anterior-plate system, in a single destabilised cervical spine-motion segment. Using fresh cadaveric cervical spine specimen C3–C7, multidirectional flexibility was measured at the C4–C5 level in an unconstrained test system, before and after destabilisation and fixation with an anterior plate with either locked or unlocked screw purchase. Direct comparison of the fixed cervical spine segments with unlocked and locked anterior-plate fixation did not demonstrate significant differences. This in vitro study documented that neither locked nor unlocked anterior-plate fixation can increase stability in all modes of testing. H-plate spondylodesis with unlocked screws seems to provide sufficient mechanical integrity in most cases of monosegmental lesions.     

一期前后联合手术减压固定治疗严重下颈椎疾病

目的:对严重下颈椎疾病,包括骨折脱位、脊髓型颈椎病及颈椎后纵韧带骨化症采取一期前后联合手术治疗,探讨该疗法的可行性和疗效。方法:本组48例中男35例,女13例;年龄21~75岁,平均48岁。严重下颈椎骨折脱位16例,伤后至手术时间5 d~3周;钳夹脊髓型颈椎病(脊髓夹持型颈椎病)19例;严重颈椎后纵韧带骨化症13例。本组均采用全麻下一期前后路联合减压,前路带锁钢板固定,自体植骨或钛网加自体骨移植。本组前路采用O rion带锁钢板17例,AO带锁钢板3例,Zephir带锁钢板28例;前路减压后采用自体骨移植9例,采用钛网加自体骨移植39例。后路采用Axis钛板螺钉固定45例,Vertex系统3例,其中采用侧块螺钉9例,颈椎椎弓根螺钉39例。结果:随访6~36个月,经椎弓根螺钉固定者术后经斜位及CT检查发现有7个椎弓根螺钉位置稍差,其中6枚穿破外侧皮质,1枚穿破内侧皮质,但无神经血管并发症。假关节形成1例,而且1枚螺钉断裂。钳夹型颈椎病19例和后纵韧带骨化症13例,术后疗效按JOA评分标准评定,术后1周及1、3、6个月评分均较术前增加(P<0.05)。结论:严重下颈椎疾病采用一期前后联合手术治疗是可行的,术后稳定性好,患者康复快。     

颈椎前路蝶形钢板内固定系统的研制及临床应用

目的研制颈椎前路蝶形钢板内固定系统,评价其生物力学稳定性,并进行临床初步应用观察。方法该系统包括蝶形钢板及三种不同用途的螺钉,采用单皮质螺钉固定及点接触原理,由医用钛合金材料 (TC4)制成。采用 14具青年男性尸体的新鲜颈椎标本,利用脊柱三维运动分析系统,比较蝶形钢板固定与 Orion钢板固定对失稳颈椎的稳定作用。临床上应用于颈椎患者的治疗 61例,其中颈椎病 26例,颈椎间盘突出症 14例,颈椎骨折脱位 18例,颈椎结核 3例。结果生物力学测试表明,该蝶形钢板内固定系统可以提供足够的颈椎稳定性,与 Orion钢板内固定系统的稳定作用相似。临床应用中, 61例患者均行颈前路减压、自体髂骨植骨融合术,并采用蝶形钢板内固定。 48例患者门诊随访 6～ 10个月,植骨块均在术后 3～ 4个月内获得骨性愈合,无钢板断裂,无螺钉松动、断裂、脱落等并发症。结论该颈椎前路蝶形钢板内固定系统具有良好的生物力学稳定性,固定效果佳,操作简便,且适合国人的解剖特点,能满足临床的需要。     

枢椎椎板螺钉在上颈椎后路固定术中的应用

目的探讨枢椎椎板螺钉固定术应用于上颈椎后路融合内固定术中的可行性。方法回顾性分析本院2012年1月—2014年12月在上颈椎后路融合固定术中采用枢椎椎板螺钉固定的19例患者资料,术中根据枢椎椎弓根是否存在缺如、细小等情况,选择置入双侧枢椎椎板螺钉或单侧枢椎椎板螺钉并对侧椎弓根螺钉,联合枕骨板螺钉和/或寰椎侧块螺钉。15例上颈椎畸形患者均有不同程度脊髓功能损害表现,日本骨科学会(JOA)评分为5~15分,平均11.5分。4例外伤性寰枢椎骨折患者有后颈部疼痛及活动障碍,疼痛视觉模拟量表(VAS)评分为2~7分,平均4.5分。术后复查患者影像学资料,观察内固定位置及植骨融合情况。结果所有手术顺利完成,未发生椎动脉、脊髓等损伤。术后复查CT,显示所有枢椎椎板螺钉位置良好,均未突破内侧皮质骨。随访时X线、CT示螺钉位置良好,无松动及断钉。所有患者术后12个月植骨均融合,上颈椎畸形患者神经功能均有不同程度改善,JOA评分为13~17分,平均15.3分。外伤性寰枢椎骨折患者颈部疼痛及活动障碍明显改善,VAS评分为0~2分,平均1.0分。结论枢椎椎板螺钉固定在上颈椎后路固定手术中方法简单安全、效果良好,对于无法行枢椎椎弓根螺钉固定的患者,枢椎椎板螺钉固定是一种安全有效的替代方法。     

A biomechanical comparison of modern anterior and posterior plate fixation of the cervical spine

STUDY DESIGN: A biomechanical study was designed to assess relative rigidity provided by anterior, posterior, or combined cervical fixation using cadaveric cervical spine models for flexion-distraction injury and burst fracture. OBJECTIVES: To compare the construct stability provided by anterior plating with locked fixation screws, posterior plating with lateral mass screws, and combined anterior-posterior fixation in clinically simulated 3-column injury or corpectomy models. SUMMARY OF BACKGROUND DATA: Anterior plating with locked fixation screws is the most recent design and is found to provide better stability than the conventional unlocked anterior plating. However, there are few data on the direct comparison of biomechanical stability provided by anterior plating with locked fixation screws versus posterior plating with lateral mass screws. Biomechanical advantages of using combined anterior-posterior fixation compared with that of using either anterior or posterior fixation alone also have not been well investigated yet. METHODS: Biomechanical flexibility tests were performed using cervical spines (C2-T1) obtained from 10 fresh human cadavers. In group I (5 specimens), one-level, 3-column injury was created at C4-C5 by removing the ligamentum flavum and bilateral facet capsules, the posterior longitudinal ligament, and the posterior half of the intervertebral disc. In group II (5 specimens), complete corpectomy of C5 was performed to simulate burst injury. In each specimen, the intact spine underwent flexibility tests, and the following constructs were tested: (1) posterior lateral mass screw fixation (Axis plate) after injury; (2) polymethylmethacrylate anterior fusion block plus posterior fixation; (3) polymethylmethacrylate block plus anterior (Orion plate) and posterior plate fixation; and (4) polymethylmethacrylate block plus anterior fixation. Rotational angles of the C4-C5 (or C4-C6) segment were measured and normalized by the corresponding angles of the intact specimen to study the overall stabilizing effects. RESULTS: Posterior plating with an interbody graft showed effective stabilization of the unstable cervical segments in all loading modes in all cases. There was no significant stability improvement by the use of combined fixation compared with the posterior fixation with interbody grafting, although combined anterior-posterior fixation tended to provide greater stability than both anterior and posterior fixation alone. Anterior fixation alone was found to fail in stabilizing the cervical spine, particularly in the flexion-distraction injury model in which no contribution of posterior ligaments is available. Anterior plating fixation provided much greater fixation in the corpectomy model than in the flexion-distraction injury model. This finding suggests that preservation of the posterior ligaments may be an important factor in anterior plating fixation. CONCLUSIONS: This study showed that the posterior plating with interbody grafting is biomechanically superior to anterior plating with locked fixation screws for stabilizing the one-level flexion-distraction injury or burst injury. More rigid postoperative external orthoses should be considered if the anterior plating is used alone for the treatment of unstable cervical injuries. It was also found that combined anterior and posterior fixation may not improve the stability significantly as compared with posterior grafting with lateral mass screws and interbody grafting.     

Minimally invasive lateral mass screws in the treatment of cervical facet dislocations: technical note

OBJECTIVE: The technique of lateral mass screw and rod or plate fixation is a major advancement in the posterior instrumentation of the cervical spine. This technique provides rigid three-dimensional fixation, restores the dorsal tension band, and provides highly effective stabilization in patients with many types of traumatic injuries. METHODS: Patient 1 was a 32-year-old man who had been in a motor vehicle accident. He presented with right C5 radiculopathy. X-ray findings included 45% anterolisthesis of C4 on C5, bilateral facet disruption, and right unilateral C4-C5 facet fracture and dislocation. The patient was placed in Gardner-Wells tongs, and the fracture was reduced with 25 pounds of traction. Patient 2 was a 56-year-old woman who had been in a motor vehicle accident that resulted in complete quadriplegia. Her initial imaging studies revealed a C3-C4 right unilateral facet fracture with subluxation. She was placed in traction, and her neurological status was reassessed. The findings of her neurological examination revealed improvement: she was found to have Brown-Séquard syndrome. Patient 3 was a 33-year-old man who was involved in a diving accident that resulted in bilaterally jumped facets at C3-C4. The patient was neurologically intact, and attempts at closed reduction were not successful. RESULTS: Patients 1 and 2 underwent anterior cervical discectomy with iliac crest autograft fusion and plating. They were then placed in the prone position, and a dilator tubular retractor system was used to access the facet joint at the level of interest. The facet joints were then denuded and packed with autograft. Lateral mass screws were then placed by means of the Magerl technique, and a rod was used to connect the top-loading screws. Patient 3 underwent posterior surgery that included only removal of the superior facet, intraoperative reduction, and bilateral lateral mass screw and rod placement. CONCLUSION: This technical note describes the successful placement of lateral mass screw and rod constructs with the use of a minimally invasive approach by means of a tubular dilator retractor system. This approach preserves the integrity of the muscles and ligaments that maintain the posterior tension band of the cervical spine.     

Anterior interbody fusion using the cervical spine locking plate

Surgical Principles The Cervical Spine Locking Plate system (CSLP) is designed to perform anterior fusions of the cervical and upper thoracic spine. The screws are locked in the H shaped plate providing intrinsic angle stability. Early osseous integration is enhanced by titanium plasma spray coating and by the hollow and perforated design of the screws. These features enhance the primary and secondary stability of the fixation. Therefore the penetration of the posterior cortex of the vertebra with the screws is not necessary, which is a decisive asset compared to conventional plate systems. This essentially diminishes the intraoperative risks. The primary stability is superior to that of conventional plate systems as the screws are tightly locked into the plate in convergence.     

颈椎前路钢板在下颈椎损伤的应用进展

对颈椎前路钢板在下颈椎损伤国外应用进展进行综述。颈椎前路钢板在设计上有限制性与非限制性两种类型,生物力学研究表明前者的固定强度明显优于后者,但易于在固定阶段对植骨块产生应力阻挡。手术指征主要为颈椎前柱损伤或颈椎后部骨与韧带复合体的损伤。但颈椎损伤存在高度不稳定时,前路钢板固定应联合颈椎后路稳定性手术。否则,术后须应用头环背心支具固定。对撑开屈曲型损伤,应警惕创伤性颈椎间盘突出,以免在牵引复位过程中发生严重的神经损伤。操作时应彻底解除脊髓前方压迫,植入三面皮质骨块,恢复前柱正常前凸,再行前路钢板固定。该方法的优点是达到了固定阶段即时稳定性,提高了植骨融合率,有利于康复。但加重了手术创伤,有发生与钢板或螺钉有关并发症的可能,晚期在临近融合区相邻椎间盘有退行性改变发生。因而在确定治疗方案时,要权衡利弊。