Submuscular Isola rod with or without limited apical fusion in the management of severe spinal deformities in young children: preliminary report

The use of growth-sparing instrumentation in pediatric spinal deformity

The management of severe spinal deformity in the growing child remains a challenging problem. Nonoperative methods range from orthotics to casting to traction; however, in certain circumstances, these techniques cannot effectively prevent deformity progression or are not tolerated by the child and surgical methods are required. Current options for surgical management of spinal deformity in the growing child include definitive spinal fusion with or without instrumentation, selective fusion, growth modulation, spinal instrumentation without fusion, or more recently, the use of the vertical expandable prosthetic titanium rib. Historically, all of these methods have a significant complication rate and despite advances in technology and instrumentation, remain problematic. This article provides an overview of current methods and outcomes for spinal instrumentation in the growing spine.

Growing rod techniques in early-onset scoliosis

BACKGROUND

The surgical treatment of severe early-onset scoliosis (EOS) is controversial. Obtaining and maintaining deformity correction, achieving adequate spinal growth, allowing lung development, and the high complication rate make surgical treatment very challenging. Growing rods are the most common method of management.

METHODS

Currently, there are 3 systems being used for the surgical treatment of EOS: single growing rod, dual growing rods, and the vertical expandable titanium prosthetic rib implant. Each system has its advantages and disadvantages. These are presented and discussed in this review.

RESULTS

The current clinical and radiographic results indicate that all 3 techniques can be effective in the surgical management of EOS. Vertical expandable prosthetic titanium rib (VEPTR), which is not considered a true growing rod system, is particularly effective in congenital scoliosis with fused ribs.

CONCLUSIONS

The current expandable spinal implant systems appear effective in controlling progressive EOS, allowing for spinal growth and improving lung development. All have a moderate complication rate, especially rod breakage and hook displacement.

Congenital scoliosis: a review and update

Vertebral anomalies causing congenital scoliosis are classified on the basis of failures of formation, segmentation, or both. The natural history depends on the type of anomaly and the location of anomaly. Patient evaluation focuses on the history and physical examination, followed by appropriate imaging modalities. The hallmark of surgical treatment is early intervention before the development of large curvatures. The surgical treatment of a congenital deformity mandates the use of neurological monitoring to minimize the risk of perioperative neurological deficit. Modern surgical techniques have evolved to include the routine use of spinal instrumentation. Patients with associated chest wall deformities or large compensatory curves may be candidates for vertical expansion prosthetic titanium rib placement or growing rods insertion to maximize growth.

Impact of spine surgery on signs and symptoms of spinal deformity

Paediatric scoliosis is associated with signs and symptoms including reduced pulmonary function, increased pain and impaired quality of life, all of which worsen during adulthood, even when the curvature remains stable. Spinal fusion has been used as a treatment for nearly 100 years. In 1941, the American Orthopedic Association reported that for 70% of patients treated surgically, outcome was fair or poor: an average 65% curvature correction was reduced to 27% at >2 year follow-up and the torso deformity was unchanged or worse. Outcome was worse in children treated surgically before age 10, despite earlier intervention. Today, a reduced magnitude of curvature obtained by spinal fusion in adolescence can be maintained for decades. However, successful surgery still does not eliminate spinal curvature and it introduces irreversible complications whose long-term impact is poorly understood. For most patients there is little or no improvement in pulmonary function. Some report improved pain after surgery, some report no improvement and some report increased pain. The rib deformity is eliminated only by rib resection which can dramatically reduce respiratory function even in healthy adolescents. Outcome for pulmonary function and deformity is worse in patients treated surgically before the age of 10 years, despite earlier intervention. Research to develop effective non-surgical methods to prevent progression of mild, reversible spinal curvatures into complex, irreversible structural deformities, is long overdue.

Early onset idiopathic scoliosis

Children with early onset scoliosis typically present before age 5 years. Radiographic criteria help to distinguish progressive cases from those that will spontaneously resolve. Severe cardiopulmonary problems may occur in untreated progressive cases. A comprehensive evaluation should be performed to identify commonly associated conditions, such as plagiocephaly, congenital heart disease, inguinal hernia, and hip dysplasia. For curves >20 degrees , magnetic resonance imaging of the neural axis is indicated to rule out occult central nervous system lesions. Surgical management should be considered when nonsurgical measures, including bracing and casting, fail to arrest progression. Surgical methods continue to evolve and are primarily directed at obtaining and maintaining curve correction while simultaneously preserving spinal and trunk growth.

Prediction of thoracic dimensions and spine length based on individual pelvic dimensions in children and adolescents: an age-independent, individualized standard for evaluation of outcome in early onset spinal deformity

STUDY DESIGN

A retrospective review of spine, chest, and pelvic dimensions of normal CT scans from 1999 to 2004 was performed.

OBJECTIVE

To determine age-independent predictors of spine and chest dimensions.

SUMMARY OF BACKGROUND DATA

Progressive thoracic deformity is associated with early-onset spinal deformities. Patients with severe early-onset scoliosis are commonly smaller and slower to grow than normal. Newer treatment approaches emphasize spine length and chest growth. Assessing treatment outcomes is hampered by the lack of normal values appropriate for diseased children. This study establishes normal range standards of chest and spine dimensions to aid in assessment of treatment outcomes.

METHODS

A total of 198 CT scans of previously healthy patients 0 to 21 years of age were measured. Measurements taken from CT scans include maximum inner chest width, anteroposterior chest depth, thoracic spine height, lumbar spine height, total spine height, and pelvic inlet width. Linear regression was applied to establish gender-specific reference ranges for spine and chest dimensions based on pelvic width.

RESULTS

Chest and spine dimensions were significantly correlated with pelvic inlet width and gender (P < 0.001). Multiple linear regression indicated that pelvic inlet width provided excellent fit in establishing gender-specific normal ranges independent of age.

CONCLUSION

Pelvic inlet width is an age-independent predictor of pediatric chest width and thoracic dimensions that may be used to assess thoracic and spine growth in early onset spine deformity patients.

Infantile scoliosis in Beals syndrome: the use of a non-fusion technique for surgical correction

Beals syndrome (congenital contractural arachnodactyl) is a genetic disorder of the connective tissue phenotypically related to Marfan syndrome. It is characterised by dolichostenomelia, arachnodactyly, multiple joint contractures, crumpled ears, hypoplastic muscles and scoliosis. The latter, the most important clinical feature of this rare condition, presents in the infantile and juvenile age group and has a tendency to rapid progression. Bracing often fails to control the scoliosis and surgery is the recommended treatment. We present our experience of two cases managed with the paediatric Isola instrumentation and a non-fusion technique.

Comparison of single and dual growing rod techniques followed through definitive surgery: a preliminary study

STUDY DESIGN

Retrospective analysis of patients treated with single and dual growing rods who had completed their course of treatment, had definitive fusion, and had a minimum of 2 years follow-up.

OBJECTIVES

To determine which technique was the most effective in the management of severe spinal deformity in young children: control of the spinal deformity, spinal growth, and the incidence of complications.

SUMMARY OF BACKGROUND DATA

Growing rod techniques provide proximal and distal segmental "claw" foundations, but their overall results through definitive fusion have not been clearly determined.

METHODS

A total of 28 consecutive patients who had growing rod procedures followed through definitive spinal fusions were analyzed. There were three patient groups: Group 1 (N = 5), single submuscular rod and short apical fusion; Group 2 (N = 16), single growing rod alone; and Group 3 (N = 7), dual growing rods.

RESULTS

The interval between initial rod insertion and definitive spinal fusion was similar in all three groups. The best overall results occurred in Group 3, whereas the patients in Group 1 had the worse results. Both Groups 2 and 3 provided good initial correction of the spinal deformity and allowed spinal growth. Group 2 had better frontal and sagittal plane balance and the lowest complication rate.

CONCLUSION

The use of growing rods is effective in controlling severe spinal deformities and allowing spinal growth. Dual rods are stronger than single rods and, therefore, provide better initial correction and maintenance of correction. The use of an apical fusion does not appear to be effective over the course of treatment.

Dual growing rod technique for the treatment of progressive early-onset scoliosis: a multicenter study

STUDY DESIGN

A retrospective case review of children treated with dual growing rod technique at our institutions. Patients included had no previous surgery and a minimum of 2 years follow-up from initial surgery.

OBJECTIVES

To determine the safety and effectiveness of the previously described dual growing rod technique in achieving and maintaining scoliosis correction while allowing spinal growth.

SUMMARY OF BACKGROUND DATA

Historically, the growing rod techniques have used a single rod and the reported results have been variable. There has been no published study exclusively on the results of dual growing rod technique for early-onset scoliosis.

METHODS

From 1993 to 2001, 23 patients underwent dual growing rod procedures using pediatric Isola instrumentation and tandem connectors. Diagnoses included infantile and juvenile idiopathic scoliosis, congenital, neuromuscular, and other etiologies. All had curve progression over 10 degrees following unsuccessful bracing or casting. Of 189 total procedures within the treatment period, 151 were lengthenings with an average of 6.6 lengthenings per patient. Analysis included age at initial surgery and final fusion (if applicable), number and frequency of lengthenings, and complications. Radiographic evaluation included measured changes in scoliosis Cobb angle, kyphosis, lordosis, frontal and sagittal balance, length of T1-S1 and instrumentation over the treatment period, and space available for lung ratio.

RESULTS

The mean scoliosis improved from 82 degrees (range, 50 degrees-130 degrees) to 38 degrees (range, 13 degrees-66 degrees) after initial surgery and was 36 degrees (range, 4 degrees-53 degrees) at the last follow-up or post-final fusion. T1-S1 length increased from 23.01 (range, 13.80-31.20) to 28.00 cm (range, 19.50-35.50) after initial surgery and to 32.65 cm (range, 25.60-41.00) at last follow-up or post-final fusion with an average T1-S1 length increase of 1.21 cm per year (range, 0.13-2.59). Seven patients reached final fusion. The space available for lung ratio in patients with thoracic curves improved from 0.87 (range, 0.7-1.1) to 1.0 (range, 0.79-1.23, P = 0.01). During the treatment period, complications occurred in 11 of the 23 patients (48%), and they had a total of 13 complications. Four of these patients (17%) had unplanned procedures. Following final fusion, 2 patients required extensions of their fusions because of curve progression and lumbosacral pain.

CONCLUSION

The dual growing rod technique is safe and effective. It maintains correction obtained at initial surgery while allowing spinal growth to continue. It provides adequate stability, increases the duration of treatment period, and has an acceptable rate of complication compared with previous reports using the single rod technique.

Inhibition of spinal fusion by use of a tissue ingrowth inhibitor

"Spinal instrumentation without fusion" techniques, which do not interfere with spinal growth, have been used extensively in the treatment of progressive spinal scoliosis in very young children. Due to subperiosteal exposure, the process of spinal instrumentation may induce spontaneous bony fusion. Instrumentation and surgical techniques have been modified in order to prevent spontaneous posterior fusion from occurring in children. An absorbable ADCON-L gel has been shown to inhibit scar and epidural adhesions following spinal surgeries. However, little is known about its influence on spinal fusion. In the present study, a single-level intertransverse arthrodesis at L4-5 on both sides was performed on each of nine pigs. Each side was randomly designed to receive autogenous bone graft with or without ADCON-L gel. The animals were followed for 10 weeks postoperatively. A fusion rate of 78% (7/9) was obtained in the autograft treatment by plain X-ray and CT evaluation, while the autograft/ADCON-L treatment yielded a 0% (0/9) fusion rate ( p = 0.001). Histomorphometric evaluation revealed that the addition of ADCON-L gel to bone graft decreased bone and bone marrow formation and significantly increased fibrous tissue formation. No statistical difference between the two treatments was found in cartilage, bone surface density, osteoid surfaces or osteoclast-covered surfaces in any zone. We conclude that ADCON-L gel mixed into autogenous bone graft can delay or decrease bone formation at spinal arthrodesis sites, thus influencing the extent of spinal fusion. This accords with our hypothesis that the use of ADCON-L gel can prevent not only the occurrence of spontaneous fusion in very young scoliosis patients after instrumentation without fusion, but also re-ossification of a decompressed spinal canal.