The migration of a broken luque rod: a case report

An exceedingly rare complication of Luque segmental spinal instrumentation in spinal fractures is described. A patient was treated for fractures of the eighth and ninth thoracic vertebra associated with traumatic paraplegia using Luque segmental spinal instrumentation. Ten years postoperatively, broken rods and sublaminar wires were found. One of the broken rods migrated caudad penetrating the sacrum and protruding into the pelvic cavity. The rod had projected into the rectum, and was extracted through the wall of the rectum and the anus. This case report emphasizes the importance of careful surgical technique and long-term follow up for patients who had undergone spinal instrumentation surgery.     

Surgery of spinal deformity in cerebral palsy. Twelve years in the evolution of scoliosis management

In order to assess the lessons learned from 12 years of surgery on patients with cerebral palsy and spinal deformity, the cases may be divided into three groups classified according to type of posterior spinal fusion, instrumentation, and time period. Group I (1976-1980) included patients who had Harrington rods, usually with Dwyer instrumentation. Group II (1980-1985) consisted of patients with unlinked Luque or wired-in Harrington rods. Group III (1985-1988) comprised patients with a unit Luque rod extending to the pelvis. Most patients were retarded nonwalkers who had total body involvement, pelvic obliquity, and severe thoracolumbar curves (Group I average, 97 degrees; Group II average, 72 degrees; Group III average, 89 degrees). The frontal plane correction at follow-up study averaged 51% in Group I, 47% in Group II, and 76% in Group III. The correction of the pelvic obliquity averaged 71% in Group I, 58% in Group II, and 86% in Group III. The general trend was toward longer fusion, use of the unit 0.625-cm Luque rod, and first-stage anterior discectomy and fusion without anterior instrumentation. The second-stage posterior arthrodesis and fusion is now performed only one week after the first-stage anterior procedure. Skeletal traction has been abandoned. The Luque rod instrumentation without fusion has also been abandoned.     

Mechanical consequences of rod contouring and residual scoliosis in sublaminar segmental instrumentation

The mechanical performance of contoured Luque rods in a neuromuscular model of spine deformity was examined to define an upper limit of deformity above which rod stresses would exceed the endurance limit for 316L stainless steel and therefore predict fatigue failure. Bovine constructs varying from 0-120 degrees scoliosis were loaded axially, with strain recordings obtained at the apex of the curve. Relatively low loads produced enough tensile stress to contemplate implant fatigue in all except the nondeformed (0 degrees) construct. Construct stiffness was found to decrease rapidly in spines with greater than 38 degrees deformity. In addition, data on patients who had suffered rod fracture from four different centers were found to compare favorably with experimental observations. We conclude that the vulnerability of Luque rod constructs to implant failure, from a mechanical standpoint, is greater than is generally assumed. Cross-linking of rods was found to increase stiffness. Methods to decrease tensile stresses in the implants and increase stiffness include external immobilization, larger diameter rods, and procedures to enhance correction.     

Spinal surgery in spinal muscular atrophy

Fifteen patients with surgical treatment of spinal muscular atrophy were reviewed. The curve pattern was thoracic in 3, thoracolumbar in 11, and double thoracic and thoracolumbar in 1. Follow-up averaged 31 months. Eleven patients underwent posterior spinal fusion with Harrington instrumentation, with segmental wiring in four, and two had Luque instrumentation. The average age at time of surgery was 14.4 years. The average curve correction was 48%; that with the pelvic obliquity corrected, 63%. Surgery is best done when the curve is approximately 50-60 degrees, and Luque sublaminar wiring of Harrington or Luque rods with no external support appears to be the procedure of choice.     

Coronal decompensation produced by Cotrel-Dubousset "derotation" maneuver for idiopathic right thoracic scoliosis

From 1985 to 1987, 82 patients with idiopathic scoliosis followed 12 to 44 months underwent selective fusion and correction of their right thoracic curves by Cotrel-Dubousset instrumentation using the "derotation" maneuver. Preoperative, postoperative, and follow-up standing anteroposterior roentgenograms of the spine were analyzed. For curves in which there was deviation from the midline (plumb line) and rotation of the lumbar segments, an increased incidence of decompensation was produced after surgery, when posterior Cotrel-Dubousset instrumentation and fusion were carried to the "stable" vertebra with one rod bend and hook alignment on the left sided derotation rod. Previous guidelines established for selective fusion with conventional posterior instrumentation (Harrington or Luque rods) may not be applicable to derotation with Cotrel-Dubousset instrumentation.     

Comparison of the failure biomechanics of spinal fixation devices

The failure biomechanics of Harrington distraction rods, modified Weiss springs, and Luque rods were studied in intact cadavers and isolated spinal columns using flexion-compression loading. Most spines fractured at T-11 or T-12 at applied loads ranging between 556 and 4220 newtons (mean = 1833 N). After Harrington distraction rod placement, the same spines failed at a mean load of 859 N (42% of control), always as a result of hook extrusion and often including lamina fracture (seven cases). When modified Weiss springs were used, the spines failed at a mean load of 1128 N (54% of control) by allowing the spine to bend to the initial failure angle; in most instances, deformities resolved when the load was reduced. Luque rods were tested in four specimens; these provided the most rigid stabilization and failed at 83% of control values. Modified Weiss springs often maintain spinal stability better than Harrington distraction rods.     

Comparison of lumbosacral fixation devices

Fusion of L4 and L5 to the sacrum has a high incidence of success. Using conventional methods, nonunion is common when long scoliosis fusions are extended to the sacrum. Three methods of instrumentation for fusing the lumbar spine to the sacrum were compared on a spine simulator test stand. Harrington distraction rods from the sacral ala to L1, Luque rods from L1 to the sacrum, and Harrington compression rods from L1 to the sacrum were tested. The use of a spine instrumentation test stand discounted biologic variation in spinal structure. Sequential loading of each test stand-instrumentation construct in torsion, flexion, extension, and lateral bending gave stiffness constants (Ks) for each test mode. Test values had reproducibility of greater than 94%. Ks illustrates the inability of Harrington distraction rods to the sacrum to resist flexion and torsion, but the ability to resist lateral bend and extension. Harrington compression rod and Luque rod constructs have equivalent stiffness in flexion and torsion. Harrington compression rods efficiently resist extension, and Luque rods resist lateral bending. Harrington distraction rods have limited use in lumbosacral junction fixation other than to correct and resist lateral bending.     

A comparative biomechanical study of spinal fixation using Cotrel-Dubousset instrumentation

A biomechanical study was performed comparing the stiffness and stability of Cotrel-Dubousset (CD) spinal instrumentation with that of segmentally wired Harrington distraction rods and segmentally wired Luque rods under conditions of single-level instability. The axial and torsional stiffness coefficients of each system were determined on a customized geometric spine simulator fashioned from stainless steel. The relative stability of each instrumentation system was then compared by mounting the fixation systems on bovine thoracic spines from 12-week-old calves, destabilized by anterior vertebrectomy to create simulated two column instability. Thirteen spines were tested. Each specimen was tested under axial and torsional loading conditions while monitoring with a personal computer-based data acquisition system was performed. The stability of first- and second-level CD instrumentation was tested on the bovine specimens. First-level CD instrumentation involved double-hook fixation one level above and below the level of instability. Second-level CD instrumentation involved fixation two levels above and below the level of instability without fixation at the intermediate level. In axial loading, double-level wired Harrington distraction rods, double-level wired Luque rods, and first-level CD rods were 26.5%, 18.4%, and 21.5%, respectively, as stable as second-level CD instrumentation. In torsion, double-level Harrington, double-level Luque, and second-level CD rods were 13%, 64%, and 34%, respectively, as stable as first level CD instrumentation. Locking hooks, double-hook configurations, and stabilizing transverse traction devices of the CD contributed to its greater stability.(ABSTRACT TRUNCATED AT 250 WORDS)     

The effect of Luque segmental sublaminar instrumentation on the rib hump in idiopathic scoliosis

The change in back shape after Luque segmental sublaminar instrumentation was assessed in the frontal, sagittal, and transverse planes in 61 patients with adolescent idiopathic scoliosis using the Integrated Shape Investigation System (ISIS) and standard radiographic techniques. Luque instrumentation was found to be an effective method of correcting thoracic and thoracolumbar curves in the frontal plane with a 59% and 63% respective reduction in the size of the preoperative Cobb angle. Despite the frontal plane correction, however, the ISIS scan showed that of the 40 single thoracic curves, the rib hump was reduced in only 6 patients, was unchanged in 27 patients, and was worsened slightly in 7 patients. By contrast, thoracolumbar and lumbar curves were corrected in all three planes with a significant cosmetic improvement.     

Adult idiopathic scoliosis treated with Luque or Harrington rods and sublaminar wiring

We reviewed the results of spinal arthrodesis that was performed, with sublaminar wires that were attached to either double L-shaped Luque rods or to a Harrington rod, in forty-two adults who had idiopathic scoliosis. The minimum length of follow-up was two years; the maximum, five years; and the average, three years. The average scoliosis measured 67 degrees preoperatively, was corrected to 37 degrees at operation, and was 44 degrees at the time of follow-up. The final correction averaged 34 per cent. A single Harrington rod and multiple sublaminar wires were used in thirty-one patients. Eighteen of the thirty-one patients had a posterior arthrodesis only and thirteen, a preliminary anterior arthrodesis followed by a posterior arthrodesis. Eleven patients had instrumentation with double L-shaped Luque rods; six of them had posterior arthrodesis only and five, a preliminary anterior arthrodesis followed by a posterior arthrodesis. One patient had neurological deficit that was related to the operation. Three patients had a pseudarthrosis, which was in the lumbar area in all of them. All three patients had had only a posterior operation. No statistically significant difference in the amount of final correction was demonstrated between the subgroups.     

Luque rod stabilization for metastatic disease of the spine

Instability of the spine caused by metastatic spread of primary tumors represents a serious risk for spinal cord or nerve root compression. In order to restore stability and relieve neural compression, a variety of surgical techniques originally used for reduction of nonpathologic spinal fractures have been applied to the problem of spinal metastases. Recently, we have utilized a technique developed primarily for correction of scoliosis to the treatment of metastatic spinal fractures. Six patients with spinal instability and neural compression secondary to metastatic tumors had segmental spinal stabilization with Luque rods, sublaminar wiring, and methyl methacrylate. Restoration of stability was successful in all cases with alleviation of preoperative pain and return to full activity. No evidence of instability occurred in this group of patients. As demonstrated by this experience and that of a few other small series, Luque rod stabilization provides a valuable addition to the techniques available for stabilization of metastatic fractures of the spine. Although the precise role of Luque rod segmental spinal stabilization in treatment of metastatic disease of the spine continues to be defined, thus far it has proved beneficial for cases of multiple vertebral body involvement or instability beyond one vertebral level.     

Multiaxis cyclic biomechanical testing of Harrington, Luque, and Drummond implants

The performance characteristics of Harrington-Moe distraction rods, paired wired Luque rods and Drummond's system were evaluated and compared when subjected to nondestructive cyclic, multidirectional biomechanical testing. Twelve fresh, frozen swine spines with intact facet joints and anterior and posterior ligamentous complexes were instrumented and tested in a specially designed pneumatic testing machine. The instrumented spines were subjected to 207 kN/m2 compression and 49 N-m torsion. Each spine was cycled 28,000 times at 1 cycle per second. Linear and angular displacements were determined by digitizing photographs and video tapes made during testing. A computer program developed and refined for the project was used to complete the data analysis. Approximately 540 items of angular and linear displacement data were collected for each spine. Inspection of the spines after cyclic, multidirectional testing revealed no change in their osteoligamentous integrity compared with pre-testing. Pre- and post-testing radiographs showed no evidence of osseous failure, hook dislodgement or wire breakage. Erosion of laminal bone at the Harrington hook attachment sites was observed. Displacement of the Harrington hooks was seen during off-axis compression-torsion testing. Fretting and deposit of metal wear debris occurred between the sublaminal wires and "L" rods. There was no evidence of loosening of either the Drummond or Luque implants or fatigue failure of any component. Analysis of the linear and angular displacement data showed that the Luque and Drummond instrumented spines displaced less in axial compression, off-axis compression and off-axis compression-torsion than the single Harrington-Moe distraction rod.(ABSTRACT TRUNCATED AT 250 WORDS)     

Results of kyphectomy with the technique of Warner and Fackler in children with myelodysplasia

Pathological lumbar kyphosis occurs in approximately 8% to 20% of patients with myelomeningocele. During the past 4 years, nine patients with an average preoperative kyphosis of 152 degrees were surgically corrected. They had a short fusion and a long stabilization with Luque rod instrumentation using a technique described by Warner and Fackler (1993). The average degree of correction was 104 degrees and, on average, 2.5 vertebrae were resected. The average surgical time was 225 minutes, and blood loss averaged 635 ml. We saw two complications: one penetration of the distal part of the rod through the sacrum after 32 months, and a dislocation of the rods out of the first sacral foramen after 33 months. From our experience, this procedure is highly demanding, but effective. It should be limited to patients below the weight of 30 kg.     

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.     

Spinal stabilization of vertebral column tumors

An analysis of indications, techniques, results of stabilization and decompression of 100 consecutive spinal tumour cases was carried out. Localized metastatic disease is best operated anteriorly. Primary malignancies are best treated with en bloc resection. Pain relief in metastatic disease is achieved by rigid stabilization. The unstable spine secondary to benign or malignant disease often requires stabilization for alleviation of pain; 132 stabilization procedures were performed in 100 patients. There were nine benign and 91 malignant tumors including 71 metastatic. Indications for stabilization were pathological fracture or following decompression. Anterior approaches including implant stabilization were used in those with metastatic disease limited to one to two levels or where significant kyphosis existed. Posterolateral decompression with Luque rod stabilization was indicated where disease was more widespread. In metastatic disease acrylic cement was used both anteriorly and posteriorly together with implant stabilization. Eighty-one percent had good to excellent relief of pain; 68 patients had neurological deficits. Significant neurological return was achieved in 40% of posterior decompressions and 71% of anterior decompressions in metastatic disease. All patients with benign tumors have solid fusions. In malignant disease the use of cement provided stability without loss of fixation in 87 of 91 procedures. Complications were 4% infection and failure of two Harrington rods without wiring, one Luque rod and two anterior constructs. The average longevity of patients treated for metastatic disease was 11.3 months.     

Luque rod instrumentation in the treatment of adolescent idiopathic scoliosis. A comparative study with Harrington instrumentation

Adolescent idiopathic scoliosis in 152 patients was treated by Luque L-rod instrumentation and early mobilisation without external support. This series was compared with a matched group of 156 patients treated by Harrington instrumentation and immobilised in an underarm jacket for nine months. All the operations in both groups were performed by one surgeon and the patients were followed prospectively for more than two years. Correction of the scoliosis in the frontal plane was similar in both groups. However, the normal sagittal contour was better maintained with Luque rods, especially in the thoracolumbar and lumbar regions, and provided less loss of correction than with Harrington rods. Neither method significantly derotated the scoliosis. All the patients with Luque instrumentation developed a solid fusion despite breakage of the sublaminar wires at one or two levels in 4.9%. There were no major neurological complications with either type of instrumentation.     

Neurological complications in segmental spinal instrumentation: analysis of 750 patients

The authors report on neurological damage caused by the use of sublaminar segmental fixation in the correction of vertebral deformities. Three groups were reviewed: 600 patients instrumented with Harrington rods and segmental wiring, 50 patients treated with the Hartshill system and 100 patients instrumented with Luque bars. All of the patients were operated on using sublaminar wiring fixation. We report two transitory neurological complications among the 600 patients with Harrington rod instrumentation and segmental wiring, two permanent neurological deficits among the 50 cases treated with the Hartshill system and none among the 100 patients instrumented using Luque bars. The purpose of this study is to analyse the causes of these neurological complications, which occurred late in all four of the cases described.Presented at the ESDS meeting, Birmingham, 1994, and selected for full publication     

Luque fixation to the sacral ala using the Dunn-McCarthy modification

The Galveston-Luque technique of fixation to the pelvis requires solid bone and a strong pelvis. Because the majority of neuromuscular patients who require fixation to the pelvis have a weak and thin illum, an alternative to the Galveston technique was sought. A technique of rod contouring was developed that takes advantage of the reliable, stout bone of the sacral ala for fixation. Twenty-four patients have been instrumented with Luque rods and fused to the sacrum over the past 4 years using the technique. There have been no complications in this short follow-up.     

Cyclic axial loading of spinal implants

The performance characteristics of Harrington distraction rods were evaluated and compared with paired wired L-rods when subjected to cyclic axial compression loading. Twelve fresh frozen swine spines with intact facet joints and anterior and posterior ligamentous complexes were instrumented and tested in a specially designed pneumatic testing device. Nine spines were displaced 2.54 cm over 10,000 cycles at a pressure of 10.3-13.8 kN/m2 (15-20 psi). Four spines were mounted in an Instron machine (Instron Engineering Corp., Canton, MA). Load displacement curves were determined for each spine without instrumentation, with Harrington distraction rod and with paired wired L-rods. Results of this cyclic axial compression testing showed that the Harrington distraction rod allowed 0.5 cm shortening in contrast to the L-rods that permitted 1.5 cm of axial displacement. Friction movement and metallic debris were noted between the sublaminal wires and the L-rods. The Luque Instrumented spine showed greater coronal plane displacement than the Harrington instrumented spines. Displacements in the sagittal plane were greater with the Harrington than Luque instrumented spines. Rotation changes in the sagittal plane were greater with the Harrington than Luque instrumented spines. Load displacement curves done on four spines indicated a wide range of applied load, 356 N (80 lbs) to 712 N (160 lbs) being necessary to displace the spines 2.54 cm. The clinician should be aware that the Luque system does not resist imposed axial compression loading in the axial and coronal planes as well as the Harrington distraction rod.(ABSTRACT TRUNCATED AT 250 WORDS)     

Internal fixation in lumbosacral spine fusion. A biomechanical and clinical study

While the posterolateral technique is the accepted fusion method for chronic mechanical back pain, the results are variable and the indications are narrow. In an attempt to resolve this problem the role of internal fixation has been explored. Relative stiffness and strength under flexion loading of four lumbosacral fixation systems--(1) translaminar facet joint screws, (2) Luque rectangular box, (3) Luque fixation to the pelvis via the Galveston technique, and (4) two-part pelvic spinal rod system--were evaluated and compared to the normal spine with and without posterior ligaments. The stiffness of the normal intact spine was found to be nonlinear: the bending moment is a function of the square of the flexion rotation. Internal fixation resulted in a twofold increase in stiffness. Facet screws were 20% stiffer and the pelvic-spinal system 2.3 times stiffer (p = 0.001) than the Luque systems but all had similar strength. A retrospective study of 135 consecutive posterolateral lumbosacral spine fusions was conducted to determine what factors improved the fusion rate, clinical results, and time to fusion. Diagnosis and previous surgical treatment, discectomy or fusion, were of no significance. The radiographic and clinical results were highly correlated (p = 0.0001). Electrical stimulation failed to improve the results. Internal fixation with facet joint screws or rods to the pelvis was found to statistically decrease the pseudarthrosis rate and reduce the time required for spine fusion (p = 0.02). The surgical technique consists of translaminar facet screws and segmental fixation to the pelvis using a new implant system.