Multisegmental Instrumentation Research Articles

[Intraoperative computed tomography-guided navigation for implant anchorage in spine surgery].

Improved accuracy of spinal instrumentation with the use of intraoperative CT (iCT). All types of posterior spinal instrumentation. None. After fixation of the spinal clamp, an intraoperative CT (iCT) is performed. The image data set can then be used for navigation of the spinal implants. The arrangement of the devices, positioning of the patient, and the exact fixation of the clamp depend on the operation technique and the anatomical region. Ahigh level of standardization is necessary for clinical success. In general, the utilization of drill guides over the use of awls and Yamshidi needles is strongly recommended. Thereby the risk of segmental vertebral rotation, especially in multisegmental instrumentation, will be reduced. The postoperative management depends on the type of surgery and is not influenced by the use of navigation with iCT. In our patient group of the first 200 surgeries with iCT (AIRO, Brainlab AG, Munich, Germany), we performed 34% cervical instrumentations, 31% percutaneous screw insertions, and 35% multisegmental open procedures including the sacrum or ilium. Two surgeries had to be converted to conventional technique due to technical problems. One misplaced S2/Ala/ilium screw had to be corrected in revision surgery. The infection rate was 2.5% and was not increased compared to conventional procedures. In the literature, asignificant reduction of radiation exposure was shown, when iCT and navigation were used. Also, in longer surgical cases the operation time could be reduced. In comparison with 3D C‑arm imaging, the image quality and screw accuracy is improved by iCT. Due to the possibility of 3D intraoperative implant control, the number of revision cases can be reduced.

Principles of Spine Instrumentation

Introduction : Spinal implants were initially, and are still, used for the supplementation of bony fusion. However, bony fusion operations were initially performed without implants.1 In the US, Wire and screw fixation of the unstable spine techniques remained to use until the pre-World War II years. 20 years after World War II, there were two major breakthroughs in spine surgery: the Harrington system for spine stabilization and deformity correction and the interspinous wiring technique of Rogers. Rogers described the technique of cervical interspinous wiring in the early 1940s. Harrington introduced his instrumentation system in 1962. Discussion : Since then, modifications of both techniques have been devised to increase their security of fixation. The next significant advance in dorsal spinal stabilization was the development of multisegmental spinal instrumentation. Multisegmental instrumentation permits sharing of the load applied to the instrumentation construct with multiple vertebrae, so that decreasing the chance of failure at the metal–bone interface.The Luque segmental wiring technique, developed in the early 1970s, was the first of this class of implants to achieve wide clinical application. Subsequent modifications have been used. Conclusion : Further modifications were the forerunners of more complex, currently used systems of universal spinal instrumentation (USI).

Komplexpathologien an der Wirbelsäule: Trauma trifft Degeneration – eine Bestandsaufnahme

Treating vertebral body fractures is challenging when there is relevant pre-existing spinal degeneration. Both vertebral body fractures and spinal degeneration are related to the physiological aging process. The increases in both are linked to increases in life expectancy. Several factors promote spinal degeneration and increase fracture risk, such as disc degeneration, spinal imbalance and osteoporosis. The main diagnostic and therapeutic challenge is to identify the sources of pain and to start appropriate therapy. A structured and advanced algorithm is then essential. Unstable fractures must always be stabilised. However, surgical strategy may be greatly influenced if there are also degenerative diseases, such as segmental decompression, multisegmental instrumentation or fusion, or complex reconstructive spondylodesis, including osteotomies. Notwithstanding this, the individual therapy concept has to be adapted to the demands and pathology of the individual patient.

Operative treatment of scoliosis in proximal spinal muscular atrophy: results of 41 patients

The early development of progressive scoliosis with pelvic obliquity is the most significant orthopaedic problem for non-ambulatory children with spinal muscular atrophy (SMA). 24 SMA patients were operated on for scoliosis using the ISOLA(®) system and 17 patients using a telescopic rod. The average age at spinal surgery was 12.3years (6.5-22.7) in the ISOLA(®) group and 6.7years (4.8-10.9) in the telescopic rod group. The Cobb angle was corrected on average from pre-operative 83°(54°-120°) to post-operative 39°(5°-70°) in the ISOLA(®) group and, respectively, from 62°(28°-86°) to 18°(0°-34°) in the telescopic rod group. Mean loss of correction at mean follow-up of 6years (3-10) was 6°(0°-33°) in the ISOLA(®) group and at mean follow-up of 8.6years (3-12) 13°(0°-49°) in the telescopic rod group excluding the patients with rod failure. The vital capacity is not worsened by these operations in comparison to the natural course. After telescopic rods were implanted, there were some unsatisfactory results due to crankshaft phenomenon and an increase of pelvic obliquity. Our recommendation for non-ambulatory SMA patients is to have definitive stabilisation using multisegmental instrumentation, starting from the age of 10 to 12years.

Accuracy of Image-Guided Pedicle Screw Placement Using Intraoperative Computed Tomography-Based Navigation With Automated Referencing, Part I: Cervicothoracic Spine

Image-guided spinal instrumentation reduces the incidence of implant misplacement. To assess the accuracy of intraoperative computed tomography (iCT)-based neuronavigation (iCT-N). In 35 patients (age range, 18-87 years), a total of 248 pedicle screws were placed in the cervical (C1-C7) and upper and midthoracic (T1-T8) spine. An automated iCT registration sequence was used for multisegmental instrumentation, with the reference frame fixed to either a Mayfield head clamp and/or the most distal spinous process within the instrumentation. Pediculation was performed with navigated drill guides or Jamshidi cannulas. The angular deviation between navigated tool trajectory and final implant positions (evaluated on postinstrumentation iCT or postoperative CT scans) was calculated to assess the accuracy of iCT-N. Final screw positions were also graded according to established classification systems. Mean follow-up was 16.7 months. Clinically significant screw misplacement or iCT-N failure mandating conversion to conventional technique did not occur. A total of 71.4% of patients self-rated their outcome as excellent or good at 12 months; 99.3% of cervical screws were compliant with Neo classification grades 0 and 1 (grade 2, 0.7%), and neurovascular injury did not occur. In addition, 97.8% of thoracic pedicle screws were assigned grades I to III of the Heary classification, with 2.2% grade IV placement. Accuracy of iCT-N progressively deteriorated with increasing distance from the spinal reference clamp but allowed safe instrumentation of up to 10 segments. Image-guided spinal instrumentation using iCT-N with automated referencing allows safe, highly accurate multilevel instrumentation of the cervical and upper and midthoracic spine. In addition, iCT-N significantly reduces the need for reregistration in multilevel surgery.

Surgical Treatment of Juvenile Idiopathic Scoliosis

Review of literature on surgical treatment of juvenile scoliosis, and results of author’s technique application are presented and analyzed. The technique allows for the spine growth continuation in conditions of three-plane correction with multisegmental instrumentation. It permits to prevent curve progression and pathologic rotation augmentation, to avoid reoperations, and to minimize a loss of surgical correction during the growth period.

[Multi-segmental fusion of scoliosis in Duchenne's muscular dystrophy].

Operations in scoliosis in patients suffering from an advanced stage of Duchenne muscular dystrophy are associated with a higher risk due to the extent of the curves, the respiratory insufficiency and frequent cardiomyopathia. Progressive scolioses in 20 wheelchair patients with an age between 10.5-18.3 years (mean 14.6 years) were treated by CDI. The mean preoperative angle in this group was 70.6 degrees, the postoperative angle 31.2 degrees (mean correction 39.4 degrees or 55.8%). The preoperative lordosis of the lumbar spine (mean angle 4.1 degrees) was corrected to 17.8 degrees postoperatively. The average intraoperative blood loss (2300 ccm) was evident more compared with idiopathic scoliosis. One neurologic complication (postoperative disturbance of bladder function) was observed. Nowadays early surgical correction and stabilization (Cobb angle > 20 degrees) has to be recommended as the treatment of choice for scolioses in Duchenne muscular dystrophy using multisegmental instrumentation methods to enable rapid mobilisation and a postoperative care without brace or cast. This conception allows a prophylactic operation including the following targets: prolongation of life expectancy, improvement of sitting position and prevention of rapid deterioration of lung function including assisted mechanical ventilation in late stages.

Augmentation of a Loosened Sacral Pedicle Screw With Percutaneous Polymethylmethacrylate Injection

Case report describing augmentation of a loosened sacral screw with percutaneous injection of polymethylmethacrylate. To highlight the advantages of percutaneous injection of polymethylmethacrylate in treatment of loosened pedicle screws. Turkey. Lumbosacral instrumentation with pedicle screws is a commonly used procedure for correcting deformity and stabilizing the spine until bony fusion occurs. Loosening of the screws is a complication of this procedure and is seen more frequently in multilevel instrumentation, particularly in those instrumentations using sacral screws. We present the case of a woman who had had L3-L4-L5-S1 instrumentation with pedicle screws who developed severe low back pain radiating to the left hip 2 months after the operation. Radiologic and clinical examination revealed that the left pedicle screw of the sacrum had loosened, and revision surgery was planned. The left sacral screw was augmented with percutaneous injection of polymethylmethacrylate. The patient was free of pain after the operation. We suggest that percutaneous polymethylmethacrylate injection around a loosened screw may be an alternative to major open revision surgery in cases of sacral screw failure in multisegmental instrumentation.

Pseudarthrosis in Adult Spinal Deformity Following Multisegmental Instrumentation and Arthrodesis

There have been few detailed reports concerning pseudarthrosis following spinal instrumentation and arthrodesis in adults with spinal deformity since the introduction of modern segmental fixation techniques. The purposes of this study were to analyze the prevalence, risk factors, and outcome scores on the Scoliosis Research Society Instrument-24 associated with pseudarthrosis following instrumentation and arthrodesis for the treatment of spinal deformity in adults. A clinical and radiographic assessment of 232 adults with spinal deformity who were treated surgically at a single institution was conducted. The average age of the patients was 40.8 years, and the operation was a primary procedure in 150 patients and a revision procedure in eighty-two patients. All patients who underwent a long (four vertebrae or more) spinal instrumentation and arthrodesis with a minimum follow-up of two years were included in the analysis. Clinical outcomes were assessed with the Scoliosis Research Society questionnaire. Forty patients had a pseudarthrosis. Factors that were found to be significantly associated with pseudarthrosis were preoperative thoracolumbar kyphosis of >20 degrees (p < 0.0001), an age of more than fifty-five years (p = 0.001), arthrodesis to S1 compared with arthrodesis to L5 or a cephalad level (p = 0.002), and arthrodesis of more than twelve vertebrae (p = 0.037). Patients with a pseudarthrosis had lower total outcome scores on the Scoliosis Research Society questionnaire, on the average, than those without a pseudarthrosis (p = 0.001). The prevalence of pseudarthrosis following long arthrodesis with use of modern segmental spinal instrumentation for the treatment of spinal deformity in adults was 17%, and the clinical outcome in these patients can be negatively affected by the pseudarthrosis.

Scheuermann kyphosis: safe and effective surgical treatment using multisegmental instrumentation.

A retrospective review was conducted on 23 consecutive patients who underwent surgical correction of Scheuermann kyphosis using modern multisegmental instrumentation. To evaluate Scheuermann kyphosis correction and complication rates. The surgical treatment of Scheuermann kyphosis remains a topic of debate. The literature of the 70s and 80s on the surgical management of this disorder using Harrington instrumentation demonstrated that operative correction is quite effective but associated with significant complications. This literature, however, may be less applicable to current clinical situations. The use of modern multisegmental instrumentation and increased awareness of potential complications may decrease the risks of current operative treatment. Hospital charts, office charts, and radiographs on 23 consecutive patients who underwent operative treatment using multisegmental instrumentation for Scheuermann kyphosis were reviewed to identify complications of surgery. Complications were classified as minor, major, or life threatening. The mean follow-up was 38 months (range 10-123 months). Preoperative kyphosis ranged from 63 degrees to 104 degrees with an average of 83 degrees. Twenty of the 23 patients (87%) underwent combined anterior release/arthrodesis with posterior arthrodesis/multisegmental instrumentation. The remaining 3 patients underwent posterior arthrodesis/multisegmental instrumentation. Postoperative total kyphosis ranged from 32 degrees to 67 degrees with an average of 46 degrees. At final follow-up, the total kyphosis ranged from 37 degrees to 75 degrees with an average of 51 degrees. Overall, we had 43% minor complications, 17% major complications, and 0% life-threatening complications. Surgical correction of Scheuermann kyphosis can be performed safely and effectively using modern multisegmental instrumentation.

Biomechanical properties of anterior thoracolumbar multisegmental fixation: an analysis of construct stiffness and screw-rod strain.

Three types of anterior thoracolumbar multisegmental fixation were biomechanically compared in construct stiffness and rod-screw strain. To investigate the effects of rod diameter and rod number on construct stiffness and rod-screw strain in anterior thoracolumbar multisegmental instrumentation. No studies have been undertaken to investigate the biomechanical effects of rod diameter and rod number in thoracolumbar anterior instrumentation. Ten fresh-frozen calf spines (T13-L5) were used. After intact analysis, a total discectomy and transection of the ALL and PLL were performed at L1-L2, L2-L3, and L3-L4 with intervertebral reconstruction using carbon fiber cages. Three types of anterior fixation were then performed at L1-L4: 1) 4.75-mm diameter single-rod, 2) 4.75-mm dual-rod, and 3) 6.35-mm single-rod systems. Single screws at each vertebra were used for single-rod and two screws for dual-rod fixation. These systems share the same basic design except rod diameter. Nondestructive biomechanical testing was performed and included compression, torsion, flexion-extension, and lateral bending. Construct stiffness and rod-screw strain of the three reconstructions were compared. The 6.35-mm single-rod fixation significantly improved construct stiffness compared with the 4.75-mm single rod fixation only under torsion (P < 0.05). The 4. 75-mm dual rod construct resulted in significantly higher stiffness than did both single-rod fixations (P < 0.05), except under compression. No statistical differences were observed in rod-screw strain between the two types of single rods, whereas dual-rod reconstruction exhibited less rod-screw strain (P < 0.05). For single-rod fixation, increased rod diameter neither markedly improved construct stiffness nor affected rod-screw strain, indicating the limitations of a single-rod system. In thoracolumbar anterior multisegmental instrumentation, the dual-rod fixation provides higher construct stiffness and less rod-screw strain compared with single-rod fixation.

Scoliosis in Duchenne muscular dystrophy

The x-linked Duchenne muscular dystrophy (DMD) is the most frequent generalized muscle disorder arising from a lack of the sarcolemmic protein "dystrophin". Patients with DMD develop in the majority a progressive scoliosis when they cease walking and/or standing at the age of 10 years and become confined to a wheelchair. Increasing muscle weakness leads to a progression of the curvature, the pelvic tilt and problems in sitting. Together with the simultaneous progressive weakness of the respiratory muscles a restrictive pulmonary insufficiency will occur. Surgical stabilization of the spine (> 20 degrees Cobb, forced vital capacity > 35%) by an adequate multisegmental instrumentation enabling early mobilization is now the treatment of choice. However, orthotic treatment may offer an acceptable compromise in exceptional cases, if the patient rejects surgical intervention or is in the late (inoperable) stages of the disease. Such a treatment is superior to a primary sitting support provision with insufficient possibilities of correction. The authors' experiences with 48 scoliosis orthoses made for 28 patients with DMD are reported. A "double plaster" cast has emerged as the best method to optimize adaption, especially in severe curvatures and the time taken for manufacturing the orthosis. A great deal of experience, patience and the consideration of the patients' individual demands are inevitable for a successful orthotic treatment.

New anterior instrumentation for the management of thoracolumbar and lumbar scoliosis. Application of the Kaneda two-rod system.

The Kaneda multisegmental instrumentation is a new anterior two-rod system for the correction of thoracolumbar and lumbar spine deformities. This system consists of a vertebral plate and two vertebral screws for individual vertebral bodies and two semirigid rods to interconnect the vertebral screws. Clinical results of 25 thoracolumbar and lumbar scoliosis patients treated with this new instrumentation were analyzed. To evaluate the efficacy of the new anterior instrumentation in correction and stabilization of thoracolumbar and lumbar scoliosis. Since Dwyer first introduced the concept of anterior spinal instrumentation and fusion for scoliosis, anterior surgery has gradually gained acceptance. In 1976, a useful modification for the anterior spinal instrumentation, which reportedly provided means of lordosation and vertebral body derotation, was described. However, some authors reported a high tendency of the implant breakage, loss of correction, progression of the kyphosis, and pseudoarthrosis as the major complications. To overcome the disadvantages of Zielke instrumentation, the authors have developed a new anterior spinal instrumentation (two-rod system) for the management of thoracolumbar and lumbar scoliosis. Anterior correction and fusion using Kaneda multisegmental instrumentation was performed in 25 patients with thoracolumbar or lumbar scoliosis. The average follow-up period was 3 years, 1 month (range, 2 years to 4 years, 7 months). There were 20 patients with idiopathic scoliosis (13 adolescents and seven adults) and five patients with other types of scoliosis, including congenital and other etiologies. All patients had correction of scoliosis by fusion within the major curve, and for 16 of the 25 patients, the most distal end vertebra was not included in the fusion (short fusion). Radiographic evaluations were performed to analyze frontal and sagittal alignments of the spine. The average correction rate of scoliosis was 83%. Over the instrumented levels, the correction rate was 90%. Preoperative kyphosis of the instrumented levels of 7 degrees was corrected to 9 degrees of lordosis. Sagittal lordosis of the lumbosacral area beneath the fused segments averaged 51 degrees before surgery and was reduced to 34 degrees after surgery. The trunk shift was improved from 25 mm before surgery to 4 mm at final follow-up evaluation. The average improvement in the lower end vertebra tilt-angle was 97% in those patients whose lower end vertebra was included in the fusion and 83% in patients whose lower end vertebra was not included in the fusion. Apical vertebral rotation showed an average correction rate of 86%. At final follow-up evaluation, all patients demonstrated solid fusion without implant-related complications. There was 1.5 degrees of frontal plane and 1.5 degrees of sagittal plane correction loss within the instrumented area at final follow-up evaluation. New anterior two-rod system showed excellent correction of the frontal curvature and sagittal alignment with extremely high correction capability of rotational deformities. Furthermore, correction of thoracolumbar kyphosis to physiologic lordosis was achieved. This system provides flexibility of the implant for smooth application to the deformed spine and overall rigidity to correct the deformity and maintain the fixation without a significant loss of correction or implant failure compared with conventional one-rod instrumentation systems in anterior scoliosis correction.

Long-Term Lumbar Facet Joint Changes in Spinal Fracture Patients Treated with Harrington Rods

Reports in the literature have questioned the practice of using Harrington distraction rods spanning unfused spinal segments for internal fixation of the fractured thoracolumbar spine. However, the long-term incidence of facet joint osteoarthritis has not been reported. This is the report on a retrospective analysis of 20 of these patients with an average follow-up period of 8.0 years. Eighty-five percent of the patients received a classification of good to excellent regarding back pain and 90% returned to their preinjury occupation. Of significance, of 75 lumbar facets traversed by rods but not fused, only two were classified as "closed" or autofused. It remains to be seen if some pedicular systems are superior to this technique in trained hands. However, multisegmental instrumentation with unisegmental fusion is possible without obtaining the severe osteoarthritic changes that animal studies have demonstrated.