Segmental spinal instrumentation using short closed wire loops

The Luque technique of segmental sublaminar instrumentation is now an established method of internal fixation in spinal surgery. The major difficulty encountered with the current technique is the danger of neurologic injury during the passage and handling of conventional wires, especially in extensive procedures. Great care is required to prevent inadvertent percussion of the wires already passed. The authors believe that by using short closed wire loops, these dangers have been minimized. Simple additional instrumentation has been devised to facilitate application of these loops. Apart from ease of application and handling, the short wire loops may offer a safer method of segmental sublaminar fixation.     

Sublaminar wiring

A technique for sublaminar wiring is described. This technique emphasizes prevention of deep penetration of the wires into the spinal canal by a method of crimping the wire around the lamina. The authors have experienced a low neurologic injury rate with this technique.     

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.     

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.     

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.     

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.     

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 chronic local effects of sublaminar wires. An animal model

An animal model was established to determine the chronic effects of sublaminar wires. Nine dogs were instrumented with sublaminar wires, sacrificed at intervals up to 155 days, then subjected to wire removal under cineradiographic myelography and histologic analysis. Common dural sac indentation by the wires during extraction averaged 47% of the total myelographic column width, with no correlation to time implanted. Epidural, subdural, and intramedullary hemorrhage, epidural adhesions, dural lacerations, cord indentations, and neural damage were all present with no correlation to time implanted. Dural thinning was more pronounced in later specimens. These data suggest that sublaminar wires are not innocuous to the dural sac and its contents in this canine experimental model.     

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.     

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.     

Risks and cost-effectiveness of sublaminar wiring in posterior fusion of cervical spine trauma

A report on the use of sublaminar wiring in the fusions of 34 patients with cervical spine injuries is given. No neurologic deficits were incurred in the use of this technique. There were no wire failures nor clinically significant complications. When compared with other forms of instrumentation to achieve similar results, the use of sublaminar wire is the most cost-effective.     

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.     

Metastatic Tumors of the Spine: Diagnosis and Treatment

Metastatic disease of the spine occurs in as many as 70% of patients with disseminated cancer and may result in vertebral collapse, spinal instability, and progressive neurologic compromise. Today, magnetic resonance imaging is the most effective means of differentiating benign from malignant causation of vertebral collapse, based on the imaging patterns and extent of marrow ablation. The more rapid the onset of the neurologic deficit, the worse the prognosis for recovery, no matter what treatment is instituted. The majority of vertebral lesions requiring decompression and stabilization emanate from the vertebral body and are best managed by anterior decompression and stabilization alone. With posterior element destruction, spinal subluxation through the involved segment, or involvement of the lumbar spine, a combination of both anterior and posterior stabilization is required. The author's preference is to perform anterior vertebral replacement with methylmethacrylate incorporating a Knodt distraction rod. This construct affords instantaneous stability that is not adversely affected by postoperative irradiation. Many devices can provide adequate posterior stabilization, but the author prefers to use Luque rods with sublaminar wire fixation. In a series of 77 patients with major neurologic compromise treated with this technique, 62% showed improvement by at least two Frankel grades, compared with fewer than 5% who improved after laminectomy decompression with or without irradiation. Nineteen of the 77 patients remained alive more than 4 years postoperatively.     

Spinous process segmental instrumentation for scoliosis

Spinous process segmental instrumentation (SPSI) for spinal fusion was devised in 1983 by Drummond et al. in an attempt to achieve the stability of segmental fixation without the known neurologic risks of passing sublaminar wires. We used SPSI in 75 scoliosis patients. Sixty-one had idiopathic scoliosis, 12 had neurogenic scoliosis, and 2 had congenital scoliosis. There were no deep infections, pseudarthroses, or neurologic complications. Two patients experienced upper hook dislodgement with 10 degrees loss of correction. We concluded that SPSI can achieve the correction of Harrington rod instrumentation and the stability of Luque rod segmental instrumentation, without the neurologic risk of sublaminar wiring.     

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.     

A biomechanical study of 3 different types of sublaminar wire used for constructs in the thoracic spine

A biomechanical study was carried out on 3 different types of sublaminar wire used in constructs to secure the thoracic spine: stainless steel monofilament wire (steel wire), titanium cable (cable), and ultra-high molecular weight polyethylene tape (tape). Two experiments were carried out. Experiment 1: Thirty-one fresh human thoracic vertebrae classified as osteoporotic (bone mineral density of <0.8 g/cm2) were used. The steel wire, cable, or tape was placed sublaminarly and a tensile force was applied until the steel wire, cable, or tape cut 5 mm through the lamina, and the force at this point was noted. Experiment 2: Seven fresh human thoracic spines (T7-T10) were biomechanically tested as follows: axial compression (250 N), flexion (7.5 Nm), extension (7.5 Nm), left lateral bending (7.5 Nm), right lateral bending (7.5 Nm), left axial torsion (10 Nm), and right axial torsion (10 Nm). This sequence was applied to the intact spine. The spine was then de-stabilized and then restabilized using one or other of the 3 different types of sublaminar wires. The biomechanical testing was then repeated on the restabilized spine and stiffness curves were generated. In the laminar cut-through test, the cut-through force for tape was higher than that for either steel wire or cable. In the biomechanical stiffness testing, there was no significant difference between the 3 different sublaminar wiring constructs in any of the loading modes tested. The results of both experiments suggest that tape is as good, if not better, than steel wire or cable as a sublaminar wiring construct material.     

The effect of sublaminar wires on the rib hump deformity during scoliosis correction manoeuvres

Introduction

During thoracic curve correction, the tightening of the sublaminar wires through concavity creates a medial and a dorsal translation of the spine. However, little is known about the effect of the sublaminar wires on the axial plane.

Methods

This is prospective case series analysis of 30 consecutive surgical patients with main thoracic adolescent idiopathic scoliosis. All of the patients were fused with hybrid instrumentation (apical concavity–sublaminar wires) and differential rod contouring (over-kyphosis concavity/under-kyphosis convexity). The degrees of the rib hump were measured with a scoliometer placed at the apex of the deformity at five different times: (1) preoperatively through the Adam’s test, and during surgery (sterilised scoliometer), (2) with the patient lying prone, (3) after the Ponte osteotomies, (4) after the apical sublaminar tightening, and (5) after convexity apical derotation and compression manoeuvres.

Results

(1) Preoperatively, the Adam’s test was 16.3° ± 4.6. (2) Lying prone and under general anaesthesia, it decreased to 11.4° ± 3.9. (3) After exposure and Ponte osteotomies, it was 7.1° ± 4. (4) After the wire tightening, it was 10.8° ± 4.7. (5) After the convexity manoeuvres, it was 4.8° ± 3.7. The degrees of the rib hump final correction were 11.6° ± 4 (70 % correction). The tightening of the sublaminar wires increased the rib hump by 3.5°.

Conclusions

The sublaminar wire tightening towards the concave rod seemed to create an effect opposite of the desired effect, increasing the apical rotation and the thoracic rib hump deformity. Convexity manoeuvres (apical screw derotation and compression) are necessary and must be coupled with an under-bending of the convex rod to neutralise this effect.

     

Posterior cervical fusion with triple-wire strut graft technique: one hundred consecutive patients.

One hundred consecutive patients were treated by the triple-wire stabilization and fusion technique for acute cervical trauma (36 patients), rheumatoid arthritis (27 patients), degenerative osteoarthritis (20 patients), congenital deformities (13 patients), or neoplasms (11 patients). The triple wire technique developed by Bohlman is versatile enough to be used at any level of the cervical spine, with 60 patients undergoing subaxial fusions, 20 with atlantoaxial fusions, and 20 with stabilization to the occiput. The immediate stability is evidenced by the fact that only two of 60 subaxial triple-wire stabilizations required the use of a Halovest, 58 being managed postoperatively in two-poster orthosis. The fusion rate was 100% for subaxial fusions. The only pseudarthrosis occurred in an occiput to C2 triple wire fixation procedure, which was managed nonoperatively. There were no iatrogenic neurologic complications, unlike the use of techniques utilizing sublaminar wires, and there were no cervical infections.     

Neurologic complications after sublaminar wiring. An experimental study in lambs.

To study possible neurologic complications, five lambs were operated on by sublaminar wiring at the thoracolumbar spine. Monitoring of the central motor pathway was carried out by percutaneous electrostimulation. A comparative anatomic study was designed to compare the magnitude of the spinal canal and the area occupied by the spinal cord at the low thoracic and lumbar level in 15 lamb, 8 pig, and 8 human spines. The following parameters were measured by slide caliper: the anteroposterior diameter of the spinal canal and the spinal cord, the length and thickness of the laminas, and the distance between each consecutive lamina. All five operated lambs showed major neurologic deficits after surgery. The results of the anatomic study suggest that there exists in humans a sufficiently ample "safety zone" that permits wire insertion without risking injury to neurologic structures. Such a "safety zone" is nonexistent in lambs and pigs unless an extensive laminectomy is performed to decrease the depth of wire penetration.     

陈旧性寰枢椎脱位与枕颈不稳的手术治疗

目的　观察两种内固定方法治疗陈旧性寰枢椎脱位与不稳的疗效。方法　自 1992—2 0 0 0年收治 36例陈旧性寰枢椎脱位与枕颈不稳的患者 ,年龄 12～ 6 1岁 ,平均 38岁 ;病程 1个月～ 8年 ,平均 16个月。 2 2例颅骨牵引复位或基本复位的 ,用 Gallie法寰枢椎固定 ,C1～ 2 髂骨植骨。 9例牵引未复位和 5例枕颈区畸形的 ,用 Ransford环固定 ,枕颈区减压 (C0 ～ C2 )和枕颈植骨融合。结果　 1例术后 4天死亡 ,35例随访 3个月～ 4年。寰枢椎固定 2 2例中 2 1例获骨性融合 ,2例复位不满意 ,其中 1例植骨不愈合。Ransford法 13例有 12例骨性融合 ,1例植骨块断裂未愈合 ,但内固定无松动。术后神经功能明显改善。结论　颅骨牵引复位的陈旧性寰枢椎脱位 ,Gallie法寰枢椎固定疗满意。 Ransford环固定对枕颈区减压和枕颈融合能提供可靠的固定作用。