Surgical correction of severe dystrophic neurofibromatosis scoliosis: an experience of 32 cases

The surgical management of severe rigid dystrophic neurofibromatosis curves is a demanding procedure with uncertain results. Several difficulties are present in such patients including a poor bone stock, sharp angulation of these dystrophic curves and dural thinning or ectasia. The aim of this work was to review the clinical and radiographic outcomes of three-dimensional correction of severe rigid neurofibromatosis curves analyzing its efficacy, safety and possible complications. Thirty-two patients were followed up for an average of 6.5 years (range 3–9 years). The average age at surgery was 14 years (range 11–19 years). All patients had typical dystrophic curves, and the apex of the deformity was thoracic (n = 13), thoracolumbar (n = 14) and lumbar (n = 5). All patients had a two-staged procedure; an anterior release followed latter by posterior hybrid instrumentation augmented by sublaminar wires. Two wires were usually placed immediately below the proximal anchor, and several sublaminar wires were always passed at the apex of the deformity. There were a total of 142 wires with an average of 6.5 wires/patient (range 5–8 wires). The mean preoperative Cobb angle of the scoliotic curve was 102.2° (range 71°–114°) corrected to an average of 39° (range 16°–49°), and the loss of correction had an average of 4°. The mean preoperative sagittal plane deformity was 49° corrected by an average of 61%, and rotation was corrected by an average of 34%. There were no dural tears during passage of the sublaminar wires, no implant-related complications and no permanent neurologic deficits. The use of extensive and vigorous anterior release with posterior hybrid instrumentation has proved useful and effective in the treatment of these severe deformities; sublaminar wires allow safe gradual correction and even distribution of forces over multiple anchor points improving the correction achieved and decreasing implant-related complications.     

Intraspinal pathways taken by sublaminar wires during removal. An experimental study

The neurological complications of segmental sublaminar stabilization that have been reported by other authors led us to perform a cineradiographic study of the pathways in the spinal canal that were taken by wires as they were being removed. The single wires were removed by pulling on the wire while keeping the wire perpendicular to the lamina; by winding the wire on the wire-extractor, with the wire being kept as nearly parallel with the lamina as possible (the roll-up technique); or by pulling on the wire while keeping the wire parallel with the lamina. During removal, thirty-four single wires conformed to the lamina and forty-one single wires compressed the dura. The roll-up technique caused the most erratic pathways. Double wires, although they were removed together, assumed independent pathways unless a wire-extractor guide was used. These findings suggest that the removal of sublaminar wires may cause dural compression in the clinical situation.     

Segmental spinal instrumentation in idiopathic scoliosis. A preliminary report

Eighty-six patients with idiopathic scoliosis who underwent a posterior spinal fusion using sublaminar segmental spinal instrumentation were analyzed retrospectively. There were two operative groups: group 1, 66 patients who had Harrington rod instrumentation and segmental wiring, and group 2, 20 patients who had Luque rod instrumentation. The clinical and radiographic data of the two groups were similar except for the passage of more sublaminar wires and increased intraoperative blood loss in group 2. Twenty intraoperative or postoperative complications occurred in 19 patients (22%) including 14 neurologic complications. Three patients (3%) had major spinal cord injuries, while 11 patients (13%) had transient sensory changes. There was no significant difference in the incidence of neurologic complications between group 1 or group 2. The remaining intraoperative complications were due either to anesthesia, positioning during surgery, or technique (dural tear). Late complications occurred in two patients in group 1 only: one each with rod breakage and hook displacement. Only one patient (1%) has required additional surgery. Our results indicate that although segmental instrumentation can be beneficial in idiopathic scoliosis, the incidence of complications, primarily neurologic, will be higher than expected. The major reason appears to be surgeon inexperience with passage of sublaminar wires. As experience increases, the incidence of complications declines and becomes comparable with conventional Harrington rod instrumentation alone.     

Experimental study of removal of sublaminar wires after spinal fixation

The result of experimental study of removal of sublaminar wires was reported. The experimental shows that sublaminar wires when with drawn at 45-degrees is safer than that at 90-degrees. Because of bony fusion, clinically could be drawn out only vertically either by rolling it up ward or down ward confirmed that there is no difference between this two methods. The cut end of wire should be short and straight. All the fixing wires became useless because of their loosening. Impressions were found on the inner face of lamina, fibrous sheaths. There is no different reactions between twisted and parallel double wires, but we recommend double parallel wires.     

The antero-posterior diameter of the lumbar dural sac does not predict sensory levels of spinal anesthesia for Cesarean delivery

PURPOSE: The lumbosacral cerebrospinal fluid (CSF) volume, as assessed by magnetic resonance imaging, is a major determinant of the intrathecal spread of local anesthetics. Ultrasound imaging of the lumbar spine allows measurement of dural sac dimensions, which we hypothesize can be used to estimate CSF volume. The purpose of this study was to investigate whether the dural sac antero-posterior diameter correlates with sensory levels of spinal anesthesia during elective Cesarean delivery (CD). METHODS: After Research Ethics Board approval and informed consent, a prospective observational study enrolled 41 patients scheduled for elective CD under spinal anesthesia. With ultrasound imaging (transverse approach, 2-5 MHz curved array probe), we measured the antero-posterior diameter of the lumbar dural sac (dural sac diameter, DSD). Spinal anesthesia was administered with 0.75% hyperbaric bupivacaine 1.6 mL, fentanyl 10 microg and morphine 100 microg, with the patient in the sitting position. Sensory block levels were assessed with ice and pinprick every five minutes until peak sensory levels (PSL) were attained. Spearman's rank correlation was used to correlate DSD with PSL and time to attain PSL. RESULTS: There were no significant correlations between DSD and PSL assessed with ice (P = 0.474) or pinprick (P = 0.583). Similarly, there was no significant correlation between DSD and time to reach PSL, and between DSD and patient demographics. CONCLUSION: The lumbar DSD, as determined by ultrasound, is not a predictor of spinal anesthesia spread. Further research is necessary to understand if ultrasound findings can be used to predict intrathecal spread of local anesthetics.     

Stability of different wiring techniques in segmental spinal instrumentation

The pullout force of sublaminar and transspinous wires for segmental instrumentation which had been inserted into different segments of human cadaver spines were campared. Four different types of wiring were tested: single and double sublaminar wires, button-wires according to Drummond's technique and button-wires with the additional use of two crimps for each spinous process. A total of 50 tests were performed. In all attempts the bone proved to be the limiting factor. None of the 300 fixed wires failed. Typical types of fractures appeared with different wiring techniques. There was no statistically significant difference between the sublaminar wiring techniques tested. However, there were significant differences between sublaminar and transspinous wiring. The transspinous techniques achieved between 30% and 45% of the pull-out strength of sublaminar techniques. The forces decreased with increasing cranialisation. In all techniques the values in the upper segment (D5–D3) were almost half those of the lower segment (L5–L3). The differences of the transspinous techniques increased cranially, in favour of the technique with additional crimps. Thus, the crimps have the strongest effect on weak spinous processes. This study demonstrates that in non-dynamic testing, the stability of the bone and not the type of wiring is the limiting parameter in segmental spinal stabilisation. As the wires are inserted in different areas, the transspinous technique shows significantly lower tension forces in comparison with sublaminar wiring.     

Removal of sublaminar wires after spinal fusion

Eighteen patients who had had spinal fusion using Harrington rods with sublaminar wires underwent removal of the implants because of tenderness over the implants. There were no important complications. At final follow-up, no patient had a change in neurological function as compared with the preoperative assessment, and all reported relief of the preoperative tenderness. We concluded that the removal of rods and sublaminar wires from patients who have had a spinal fusion is clinically safe and effective.     

Biomechanical evaluation of a new fixation device for the thoracic spine

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

Depth of intraspinal wire penetration during passage of sublaminar wires

A major concern with the use of sublaminar wires for segmental spinal instrumentation is the risk of neurologic compromise associated with repeated passage of wires through the epidural space. Because of the inability to visualize the wire tip during its sublaminar passage, the surgeon is unable to appreciate the depth of wire penetration (DOWP). The purpose of this investigation was to determine, through direct measurement, the depth of intraspinal penetration during the passage of sublaminar wires. Using their model, the authors have been able to define the optimal parameters for safe wire passage. Careful attention to maintaining contact between the wire tip and the under-surface of the lamina, using a wire of optimal configuration, will result in minimal DOWP and reduce the possibility of neurologic compromise.     

A study of the mechanical stability of scoliosis constructs using variable numbers of sublaminar wires

Sublaminar wiring with posterior instrumentation is one of the methods used when long fusions involving 10-12 thoracolumbar levels are required. Classically, wires are used at every consecutive level to make the construct as rigid as possible, although complications like dural tears, cerebrospinal fluid leak, and neurological deficit have been reported during their passage. We compared the mechanical stability under torsional strain of five specimens of each of three construct designs, by static and fatigue testing, using an electro-servo-hydraulic testing machine. In construct A, a contoured Hartshill rectangle was used from T2 to L2, with sublaminar wires passed at every level. In construct B, the Hartshill rectangle was wired to the spine at every alternate level. In construct C, every alternate level was wired except at the proximal end, where two consecutive levels were wired. Industrially fabricated spine models were used to prepare these constructs. The intervertebral motion within the construct was measured using the Fastrak magnetic field sensor device. On static testing, no statistically significant difference was found in the rotational displacement of the three construct designs. On fatigue testing, all samples of construct B consistently failed, with breakage of the wire at the most proximal level on the left side. But on adding additional wires to the next level (construct C), all five samples withstood fatigue testing at 300 N load to three million cycles. We conclude that wiring alternate levels instead of every level does not compromise the stability of the construct, provided that the most proximal two levels are consecutively wired. This practice would minimise the risk of dural tears and cord damage during wire passage and reduce surgical time, not to mention the economic benefits.     

The pathomorphology of spinal stenosis as seen on CT scans of the lumbar spine

This study examines different morphologic measurements in the evaluation of patients with lumbar spinal stenosis. Preoperative CT scans from 24 patients who underwent surgery for central lumbar stenosis were analyzed. No correlation was observed between the size of the bony spinal canal and the size of the dural sac. A new measurement, the transverse area of the dural sac, is introduced. Normal values are provided. Correlation between the cross-sectional area of the dural sac and the anteroposterior diameter of the dural sac was excellent.     

Safety of sublaminar wires with Isola instrumentation for the treatment of idiopathic scoliosis

STUDY DESIGN: To investigate the incidence of acute neurologic complications of use of sublaminar wires with third-generation spine instrumentation for the treatment of idiopathic scoliosis. OBJECTIVES: To assess the safety of sublaminar wires in the surgical treatment of idiopathic scoliosis. SUMMARY OF BACKGROUND DATA: The use of sublaminar wires in spine deformity for neuromuscular scoliosis and the Luque system has been reported. Use of sublaminar wires is an integral part of the technique in the surgical treatment of spine deformity with Isola instrumentation (AcroMed, Cleveland, OH). To date, the safety of this technique has not been documented. METHODS: The average age of the patients was 37 years (range, 11-74 years). Preoperative diagnosis was adolescent idiopathic scoliosis in 75 patients and adult idiopathic scoliosis in 66. One hundred nine were primary surgeries, and 32 were revision. Detailed evaluation of the curve type, curve magnitude, number of vertebrae instrumented, level of vertebrae wired, postoperative neurologic deficit, and the findings of intraoperative spinal cord monitoring was performed. Wires were always passed just before corrective maneuvers were performed. RESULTS: A total of 1366 wires were placed, 65% (n = 888) in the thoracic region, 22% (n = 300) in the thoracolumbar, and 13% (n = 178) in the lumbar. No permanent change in intraoperative spinal cord monitoring was detected. Stagnara wake-up test was performed in all patients. No patient with adolescent idiopathic scoliosis had neurologic complication. Two adults underwent revision surgery and had transient dysesthesia in the leg, which completely resolved with observation. CONCLUSION: Despite the increasing complexity of spinal instrumentation systems, sublaminar wire placement is a safe and useful adjunct in the surgical treatment of neurologically intact patients with idiopathic scoliosis.     

Luque instrumentation in degenerative conditions of the lumbar spine

The authors report on the experience obtained in using L-rods and sublaminar wires in obtaining lower lumbar fusions of three or more levels in degenerative diseases of the lumbar spine. A successful fusion was obtained in 86% of the patients. The technique, while offering a satisfactory method of fusion, does violate the spinal canal with sublaminar wires with potential for neurologic injury. Specifically, the passage of sacral wires should be avoided.     

MRI中椎管及硬膜囊大小与单节段腰椎间盘突出症治疗的相关性研究

目的:探讨MRI中椎管及硬膜囊大小对椎间盘突出症治疗方法选择的参考价值。方法:对2010年1月至2012年12月非手术和手术治疗的144例腰椎间盘突出症患者的临床资料进行回顾性分析。其中非手术组91例,男55例,女36例,年龄20～ 68岁,平均(43.37±12.48)岁;手术组53例,男28例,女25例,年龄20～ 64岁,平均(42.98±12.95)岁。采用JOA评分(29 分)对两组患者治疗前后的临床表现(包括症状、体征、日常活动受限度和膀胱功能)及效果进行量化评价。同时在腰椎MRI T2轴位测量椎管和硬膜囊大小的相关参数(包括椎管正中矢径和有效矢径、侧隐窝宽度、椎管和硬膜囊面积),并计算有效矢径/正中矢径、隐窝宽度/正中矢径和膜囊面积/椎管面积的比值。将两组患者的各参数值进行统计学比较,并分析其与治疗前JOA评分的相关性。结果:(1)144例患者随访1～3年,平均2.1年。治疗前非手术组和手术组的JOA评分分别为16.27±2.96和12.64±3.30,差异有统计学意义(t=6.319,p<0.01).末次随访非手术组与手术组比较,JOA评分(25.41±2.22 vs 25.76±2.29;t=-0.853,p=0.396>0.05),改善率[(72.95±12.54)% vs (76.80±9.45)%;t=-1.855,p=0.065>0.05]和优良率(84.91% vs 78.02%;χ₂=3.704,p=0.295>0.05)的差异均无统计学意义;但非手术组的复发率(14.29%)较手术组(5.67%)高。(2)手术组椎管正中矢径和有效矢径、侧隐窝宽度、椎管和硬膜囊面积、有效矢径/正中矢径、隐窝宽度/正中矢径均小于非手术组,硬膜囊面积/椎管面积则大于非手术组,两组比较差异均有统计学意义(p<0.01).(3)治疗前JOA评分与椎管正中矢径和有效矢径、侧隐窝宽度、椎管及硬膜囊面积有正相关性(p<0.01);与有效矢径/正中矢径、侧隐窝宽度/正中矢径也有正相关性(p<0.05);而与硬膜囊面积/椎管面积有负相关性(p<0.01).结论:非手术和手术治疗腰椎间盘突出症均能获得良好的效果,但非手术治疗复发率较高。术前测量椎管及硬膜囊的MRI参数对椎间盘突出症治疗方法的选择有一定的临床参考价值,但需要进一步完善和临床验证。     

Surgical treatment of adolescent idiopathic scoliosis. A comparative analysis

Three hundred and fifty-two patients had a one-stage posterior spinal arthrodesis between 1960 and 1984 using one of four types of instrumentation: a Harrington distraction rod, Harrington distraction and compression rods, Harrington distraction and compression rods with a device for transverse traction, and a Harrington distraction rod with sublaminar wires. All of the patients were female (age-range, eleven to nineteen years), and all had idiopathic scoliosis with a single right or double thoracic curve. The minimum length of follow-up was two years. No significant difference was found among the four groups relative to the amount of correction that was obtained at operation or maintained two years after operation. An average of 13.5 per cent of correction was lost during follow-up in the patients who were treated with postoperative immobilization, and an average of 27 per cent was lost in the patients who were treated with sublaminar wires without immobilization. The use of a straight Harrington rod reduced normal thoracic kyphosis, the addition of a compression rod corrected hyperkyphosis, and the use of a rod with sublaminar wires corrected thoracic hypokyphosis or thoracic lordosis.     

Comparison of segmental spinal instrumentation devices in the correction of scoliosis

Harrington distraction rods with either sublaminar wires or convexity compression rods and transverse loading wires were used to treat idiopathic scoliotic patients. Laboratory measurement of transverse forces and orthographic projection of the apical vertebra enabled calculation of x- and y- plane forces in addition to torque. The construct utilizing sublaminar wires generated more favorable corrective vectors. Both devices tended to further rotate the scoliotic spine. Use of the compression apparatus should be limited to spines where reduction of kyphosis is desirable.     

A modular spinal rod linkage system to provide rotational stability

The effect of cross linkage on the in vitro stability of paired Harrington distraction rods was studied in an unstable fracture model using calf spine segments. Cross linkage used in conjunction with sublaminar wires significantly improved torsional stability, improved lateral bending stability, and had no adverse affect on stability for axial, forward flexion, or extension loading compared to rods alone, rods with bridges, and wired rods.     

Study of dural sac cross-sectional area in early and late phases after lumbar decompression surgery

Background contextLumbar magnetic resonance imaging (MRI) in the early phase after lumbar decompression surgery sometimes reveals an absence in the expansion of the dural sac, regardless of the presence or absence of clinical symptoms; the reason for such a condition is often difficult to explain. There are some reports that compared the dural sac area between the preoperative and early postoperative phases; however, no report exists that compares the early and late phases after lumbar decompression surgery.PurposeThe purpose of this study was to compare changes in the dural sac cross-sectional area (CSA) in the early and late phases after lumbar decompression surgery. Factors related to the insufficient increase in the postoperative dural sac CSA were also analyzed.Study designThe dural sac CSA preoperatively and in the early and late phases after lumbar decompression surgery was analyzed retrospectively.Patient sampleOf 105 patients who underwent lumbar decompression surgery and MRI within 1 week and again more than 1 month after surgery, 83 patients (38 men, 45 women; mean age 65.6 years) were included in this study.Outcome measuresCross-sectional areas of the dural sac.MethodsThe dural sac CSA was measured within 1 week (early phase) and more than 1 month (late phase) after surgery, using T2 axial plane MR images. The preoperative and the early and late postoperative CSAs were measured at the same site. The relationship between the dural sac area and age and presence of dural injury was also analyzed.ResultsThe mean area of the dural sac preoperatively and in the early and late postoperative phases was 71.2±4.9, 102.2±5.7, and 164.1±6.9 mm², respectively. The mean area increased significantly (p<.001) between the preoperative and postoperative early phases and between the early and late postoperative phases. The dural sac area in the early (p=.16) and late (p=.086) phases did not differ significantly between patients aged 75 years or more and those aged less than 75 years. In the case of lumbar spinal stenosis, patients with a preoperative dural sac area of less than 60 mm² showed a significantly (p<.001) smaller dural sac area in the early and late postoperative phases, compared with patients with a preoperative dural sac area of 60 mm² or more. No significant increase was observed in the dural sac area with regard to the presence or absence of dural injury.ConclusionsThe dural sac area increased significantly between the early and late postoperative phases. No significant difference in the dural sac CSA between the early and late postoperative phases was observed with regard to age or the presence/absence of dural sac injury. A smaller preoperative dural sac CSA resulted in a smaller dural sac CSA in the early and late postoperative phases.     

老年腰椎椎管狭窄症患者术中硬膜囊撕裂位置及术中术后处理对策

目的探讨老年腰椎椎管狭窄症患者手术发生硬膜囊撕裂的解剖学机制,比较撕裂位置及术中、术后处理对策。方法回顾性分析2012年01月~2014年01月本院行腰椎后路手术的216例〉70岁老年患者,记录患者一般资料、病程时间、术前诊断、手术方式和节段、术中硬膜囊撕裂的位置、术后脑脊液漏情况和处理方法以及并发症等。结果共计151例患者入选,其中男89例,女62例,年龄70~93岁,平均78.12岁。术中发生硬膜囊撕裂共计34例,术后出现脑脊液漏23例,硬膜囊撕裂位置发生率硬膜囊后外侧〉根袖〉硬膜囊外侧〉硬膜囊腹侧。术中采取硬膜囊缝合修补、明胶海绵压迫、生物蛋白胶粘合等处理,术后常规给予预防感染、神经根脱水、补液等治疗,均于术后3~10 d拔管,3~4周切口愈合,全部患者未出现严重并发症。结论 〉70岁老年腰椎椎管狭窄症患者术中硬膜囊撕裂及术后脑脊液漏的发生率高于整体人群,且多位于硬膜囊后外侧及根袖,术中及时发现并仔细缝合或修补破损的硬膜、术后间断夹闭引流管、延长拔管时间能获得良好的效果。     

Studies of an L-rod sublaminar wire spinal fusion

The spine of a 25-year-old man with Duchenne muscular dystrophy was studied postmortem, 8 years after spine fusion with L-rods and sublaminar wires. The fusion was solid. Instrumentation appeared to have had no adverse effects on the spinal cord or meninges or in the epidural space. When wire removal from the spinal canal and fusion mass was studied, increased penetration of the wires into the spinal canal was noted.