Growing rod techniques in early-onset scoliosis

Orthopedic Management of Scoliosis by Garches Brace and Spinal Fusion in SMA Type 2 Children

BACKGROUND

Scoliosis is the most debilitating issue in SMA type 2 patients. No evidence confirms the efficacy of Garches braces (GB) to delay definitive spinal fusion.

OBJECTIVE

Compare orthopedic and pulmonary outcomes in children with SMA type 2 function to management.

METHOD

We carried out a monocentric retrospective study on 29 SMA type 2 children who had spinal fusion between 1999 and 2009. Patients were divided in 3 groups: group 1-French patients (12 children) with a preventive use of GB; group 2-French patients (10 children) with use of GB after the beginning of the scoliosis curve; and group 3-Italian patients (7 children) with use of GB after the beginning of the scoliosis curve referred to our centre to perform orthopedic preoperative management.

RESULTS

Mean preoperative and postoperative Cobb angle were significantly lower in the group 1 of proactively braced than in group 2 or 3 (Anova p = 0.03; Kruskal Wallis test p = 0.05). Better surgical results were observed in patients with a minor preoperative Cobb angle (r = 0.92 p <  0.0001). Fewer patients in the group 1 proactively braced required trunk casts and/or halo traction and an additional anterior fusion in comparison with patients in the group 2 and 3. Moreover, major complications tend to be less in the group 1 proactively braced. No significant differences were found between groups in pulmonary outcome measures.

CONCLUSIONS

A proactive orthotic management may improve orthopedic outcome in SMA type 2. Further prospective studies comparing SMA management are needed to confirm these results.

LEVEL OF EVIDENCE

Therapeutic Level III. See Instructions to Authors on jbjs.org for a complete description of levels of evidence (Retrospective comparative study).

Safety and compatibility of magnetic-controlled growing rods and magnetic resonance imaging

PURPOSE

Magnetically controlled growth rods (MCGRs) are a new technology for the management of early-onset pediatric deformity enabling guided spinal growth by controlling the curvature. These rods contain a rare earth magnet and are contraindicated for MRI. We have investigated the behavior MCGRs to determine whether MRI adversely affects rod properties and to determine the extent of image distortion.

METHODS

This is an in vitro experiment using two magnetic growth rods secured in a 1.5 T MRI. A gradient echo sequence MRI was performed to evaluate whether the rods elongated, contracted or rotated during scanning and a phantom model was used to evaluate the amount of artifact induced.

RESULTS

The rod was not activated or subsequently impaired by the process of MRI. Image distortion of 28.9 cm along the long axis of the magnet and 20.1 cm perpendicular to this was seen with extension 10.6 cm cranial to the magnet housing. No negative effect was demonstrated on the magnetic rod elongation mechanism.

CONCLUSIONS

This study has demonstrated that there are no detrimental effects of MRI on the MCGR and imaging of the head and neck phantom can still be interpreted. Further in vivo study is warranted.

Distraction magnitude and frequency affects the outcome in juvenile idiopathic patients with growth rods: finite element study using a representative scoliotic spine model

BACKGROUND CONTEXT

Growth rods are used to limit the progression of scoliosis without restraining the opportunity for the spine to grow. However, major complications like rod breakage, screw loosening, and altered sagittal contour have been encountered.

OBJECTIVE

To analyse the effect of the magnitude of distraction forces on the T1-S1 growth, maximum von Mises stresses on the rods, sagittal contours, and load at the pedicle screw-bone interface and quantify the maximum stresses on the rod for a period of 24 months using different frequencies of distraction in a representative scoliotic spine model.

STUDY DESIGN

A representative finite element model of a juvenile scoliotic spine was used to study the effect of magnitude and frequency of distraction on growth rods.

METHODS

A representative scoliotic model was developed and instrumented using proximal foundation, distal foundation, and rods. Part 1: simulation steps comprised 6 months of growth under various distraction forces to analyze effects of distraction force on the biomechanics of the spine and instrument. Part 2: simulation steps comprised 24 months of growth under various intervals of distraction to analyze effects of distraction interval on the propensity of rod fracture.

RESULTS

Part 1: an optimal distraction force exists for which the growth is sustained with minimum stress on the rod, lower loads at screw-bone interface, and unaltered sagittal contours. Part 2: the stresses on the rods were highest for 12-month distraction (2 distractions in 2 years) and lowest for 2-month distraction (12 distractions in 2 years).

CONCLUSIONS

The data and trend suggest that as the distraction forces vary so do the effects on spinal growth. The results of this study also signify the importance of shorter distraction period in reducing the stresses on the rods.

The impact of posterior temporary internal distraction on stepwise corrective surgery for extremely severe and rigid scoliosis greater than 130°

AIM

To investigate the efficacy and safety of temporary internal distraction corrective surgery for extremely severe scoliosis.

METHODS

Eleven scoliosis patients (3 males and 8 females) with curves ≥130° (mean 148.8°; range 130°-157°) who underwent a two-stage surgery, including a posterior temporary internal distraction correction and definitive posterior spinal correction with posterior pedicle screw instrumentation from 2008 to 2011 were retrospectively reviewed. Minimum follow-up was 2-years (mean 41.8 months; range 27.0-63.0 months). The analysis focused on the impact of temporary internal distraction on curve correction, pulmonary function tests (PFTs), complications and surgical outcomes. Neurosurveillance of sensory (somatosensory-evoked potentials) and motor (motor-evoked potentials) potential was performed in all cases. Posterior instrumentation was used in all patients.

RESULTS

After the use of internal distraction, the preoperative major curve (mean 148.8°; range 130°-157°) was corrected to a mean of 79° (range 63°-87°), the T5-T12 kyphosis Cobb angle (mean 79°; range 30°-97°) was corrected to a mean of 59° (range 20°-75°), the coronal imbalance (mean 0.8 cm; range -3.6 to 2.8 cm) was improved to a mean of 0.6 cm (range -1.5 to 2.0 cm), the forced vital capacity percentage (FVC%) was improved from 59.3 ± 11.6 to 68.7 ± 13.7, and the forced expiratory volume in 1 s (FEV1%) was improved from 61.4 ± 13.6 to 71.3 ± 9.3. The average increase in body height was 6.7 cm, and the dorsum razor was corrected to 3-5 cm. During definitive surgery, the final major curves were corrected to a mean of 55° (range 32°-72°), the T5-T12 kyphosis Cobb was corrected to 35° (range 15°-68°), the coronal imbalance was improved to 0.5 cm (range -1.2 to 1.8 cm), the FVC% was improved to 71.2 ± 8.3, the FEV1% was improved to 76.3 ± 16.7, the increase in body height was 3.1 cm, and the dorsum razor was corrected to 1-3 cm. The mean interval time between the two surgeries was 3.5 months. None of the patients exhibited postoperative neurologic deficits or infections. No instrument complications were found during the final follow-up.

CONCLUSIONS

Temporary internal distraction in a two-stage corrective surgery provided patients who had extremely severe and rigid scoliosis, an effective and safe solution for scoliosis without significant complications.

A classification of growth friendly spine implants

BACKGROUND

Various types of spinal implants have been used with the objective of minimizing spinal deformities while maximizing the spine and thoracic growth in a growing child with a spinal deformity.

PURPOSE

The aim of this study was to describe a classification system of growth friendly spinal implants to allow researchers and clinicians to have a common language and facilitate comparative studies. Growth friendly spinal implant systems fall into 3 categories based upon the forces of correction the implants exert on the spine, which are as follows: Distraction-based systems correct spinal deformities by mechanically applying a distractive force across a deformed segment with anchors at the top and bottom of the implants, which commonly attach to the spine, rib, and/or the pelvis. The present examples of distraction-based implants are spine-based or rib-based growing rods, vertical expandable titanium rib prosthesis, and remotely expandable devices. Compression-based systems correct spinal deformities with a compressive force applied to the convexity of the curve causing convex growth inhibition. This compressive force may be generated both mechanically at the time of implantation, as well as over time resulting from longitudinal growth of vertebral endplates hindered by the spinal implants. Examples of compression-based systems are vertebral staples and tethers. Guided growth systems correct spinal deformity by anchoring multiple vertebrae (usually including the apical vertebrae) to rods with mechanical forces including translation at the time of the initial implant. The majority of the anchors are not rigidly attached to the rods, thus permitting longitudinal growth over time as the anchors slide over the rods. Examples of guided growth systems include the Luque trolley and Shilla.

CONCLUSIONS

Each system has its benefits and shortcomings. Knowledge of the fundamental principles upon which these systems are based may aid the clinician to choose an appropriate treatment for patients. Having a common language for these systems may aid in comparative research. Vertical expandable titanium rib prosthesis is used with humanitarian exemption. The other devices mentioned in this manuscript are not approved for growing constructs by the Food and Drug Administration and are used off-label.

Use of Rib-Based Distraction in the Treatment of Early-Onset Scoliosis Associated With Neurofibromatosis Type 1 in the Young Child

STUDY DESIGN

This study was an institutional review board-approved retrospective review of a prospectively collected multicenter database for rib-based distraction systems used in the treatment of young children with early-onset scoliosis associated with neurofibromatosis type 1 (NF-1).

OBJECTIVE

To evaluate the effectiveness of rib-based distraction and associated complications in managing scoliosis in the growing child with NF-1.

SUMMARY OF BACKGROUND DATA

Patients with NF-1 commonly have scoliosis with curves that can be dysplastic and progressive and respond poorly to bracing. Rib-based distraction systems have recently been described in the management of these complex patients. The efficacy and complication rate using these systems have not previously been reported.

METHODS

Twelve children with NF-1 and scoliosis who were treated with rib-based distraction systems were identified from a prospectively collected multicenter registry. Preoperative and postoperative Cobb angle and T1-S1 spine height were measured from posteroanterior radiographs. The number of lengthenings, age at implantation, years of follow-up, and complications were also acquired from the registry or patient charts.

RESULTS

Mean age at implantation of the Vertical Expandable Prosthetic Titanium Rib device was 6.34 years. Mean preoperative Cobb angle was 66.3°. Average follow-up was 5.2 years. Mean postoperative Cobb angle was 60.8° after an average of 7.75 lengthening procedures (range, 2-16 procedures). T1-S1 height increased in all patients. There were 17 complications in 8 patients (device migration in 6, wound dehiscence in 3, rod breakage in 2, medical issues in 5, and 1 revision for progression of curve). Of the 17 complications, 10 were grade I, 1 was grade II, and 6 were grade IIA; there were no grade III complications.

CONCLUSIONS

The use of rib-based distraction is an effective and relatively safe method of stabilizing curve progression through growth in severe dysplastic scoliosis associated with NF-1.

Reckoning: Assessment of a 21-year activity in spine surgery

Introduction: Of the world-wide used Cotrel–Dubousset instrumentation and surgical technique providing breakthrough for the three-dimensional correction and multi-segmental fixation of spinal deformity surgery in Hungary is linked to the author’s name, who carried out 1655 spine deformity surgeries in the last 21 years. Aim: The aim of the author was to discuss his own results in the field of spine surgery and compare his own data to those published in the international literature. Method: At the beginning hooks, followed by hybrid instrumentation with hooks in thoracic area and transpedicular screws in lumbar spine have been used for the segmental fixation. During the correction process, initially the classic derotation maneuver was used, followed by the translation and then the in situ bending techniques and, finally, a combination of the above three techniques have been applied. Results: In addition to the restoration of normal sagittal balance, an average of 40.8° (SD, 25.9), a 65.5% correction was achieved in the frontal plane, which partly exceeds and partly consistent with the published international results. The incidence of inflammation (3.9%), and mechanical complications (1.7%) was similar to the international average, while the incidence of neurological complications (0.48%) was slightly lower than the average of international data. Conclusions: The author believes that the better correction results as compared to the international average could be due to the always consistent application of the Cotrel–Dubousset instrumentation correction philosophy based on the meticulous segmental analysis of spine deformities. Orv. Hetil., 2015, 156(15), 598–607.

Analysis of retrieved growth guidance sliding LSZ-4D devices for early onset scoliosis and investigation of the use of nitinol rods for this system

STUDY DESIGN

Analysis of volumetric wear loss of retrieved growth guidance sliding devices LSZ-4D for treatment of early onset scoliosis and laboratory in vitro wear test for comparison of wear resistance of alloys Nitinol, Ti, and cobalt chromium (CoCr).

OBJECTIVE

To evaluate quantitatively the amount of wear debris from the sliding LSZ-4D device and to investigate the potential of using Nitinol for replacing Ti alloys in spinal instrumentation. To do that, wear resistance of Nitinol, Ti, and CoCr was compared.

SUMMARY OF BACKGROUND DATA

There are little data regarding the amount of wear debris associated with growth guidance sliding devices for patients with early onset scoliosis and the wear resistance of superelastic Nitinol compared with Ti and CoCr.

METHODS

Volumetric wear loss was measured on LSZ-4D devices made from titanium alloy Ti6Al4V and each consisted of 2 rectangular section (6 × 4 mm) rods and 40 ± 8 fixture elements (20 ± 4 hooks and 20 ± 4 clips) retrieved from 3 patients (implantation period, 3.5-5.8 yr). Images of wear scars were taken on Bruker interferometer microscope and incorporated into MATLAB software. Wear resistance of Nitinol, Ti, and CoCr was studied using reciprocation pin-on-disk wear test in bovine serum at 37°C ± 1°C.

RESULTS

The volume wear rate of LSZ-4D device was found to be 12.5 mm per year from which 5 mm³ per year is the wear debris of the rod and 7.5 mm per year is the contribution of fixtures. Wear resistance of Nitinol is 100 times higher than that of Ti and comparable with that of CoCr.

CONCLUSION

Application of wear-resistant coatings on Ti components in growth guidance sliding devices for the treatment of early onset scoliosis will be useful. High wear resistance of Nitinol combined with its superelastic and shape memory properties could make application of Nitinol rods for spinal instrumentation beneficial.

Spinal growth modulation with posterior unilateral elastic tether in immature swine model

BACKGROUND CONTEXT

Fusionless scoliosis surgery is frequently performed in children. Many studies have analyzed the effects of spinal growth modulation by tethering the anterior and anterolateral aspects of the spine in animal models. However, few studies have reported the disc health and spinal motion in spines with posterior unilateral elastic tethering.

PURPOSE

To analyze the regional radiography, biochemistry, and histology of spinal motion segments fixed by posterior unilateral elastic tethering.

STUDY DESIGN

A randomized controlled trial.

OUTCOME MEASURES

Preoperative and postoperative radiographs of the spines were taken. After an 8-week recovery period, the spines were harvested en bloc and underwent radiographic, biochemical, and histologic analyses.

METHODS

Fifteen 3-month-old swine were randomly divided into three groups. Instrumentation was performed posteriorly in the swine. In the elastic fixation (EF) group, five swine were instrumented on the left side of the lumbar vertebrae from L1 to L5 with pedicle screws that were connected with a unilateral elastic tether with tension to produce a curve on the spine. The same surgery was performed in the five animals of the metal rod fixation (MF) group, in which the screws were connected with metal rods and curves were established. In the control group, five animals were instrumented with five screws with no connecting cable.

RESULTS

Scoliosis and lordosis were created in the coronal and sagittal planes in both the EF and MF groups. On average, the Cobb angles were 12.16°±1.37° and 9.10°±2.02° (p=.023) in the coronal plane and 17.44°±11.29° and 5.32°±3.06° (p=.049) in the sagittal plane in the two groups, respectively. The vertebrae and discs wedged on the tethered side in the two groups showed no significant differences (p>.05). The thickness of end-plate epiphysis on the fixed side was significantly decreased in the two groups (p=.032 and p=.024). No apparent change was found in the gross morphology of the discs in the two groups. The distribution of collagen types I and II decreased and that of matrix metalloprotease-3 (MMP-3) increased in both the EF and MF groups. Additionally, the proteoglycan synthesis decreased in the two groups.

CONCLUSIONS

Unilateral elastic tethering resulted in vertebral wedging and scoliosis. Although changes in collagen and MMP-3 distribution, proteoglycan synthesis, end-plate epiphysis, and disc thickness were observed, the tethered discs and end plates did not demonstrate gross morphologic signs of degeneration.

Apical and intermediate anchors without fusion improve Cobb angle and thoracic kyphosis in early-onset scoliosis

BACKGROUND

The main goal of treatment in early-onset scoliosis is to obtain and maintain curve correction while simultaneously preserving spinal, trunk, and lung growth. This study introduces a new surgical strategy, called the modified growing rod technique, which allows spinal growth and lung development while controlling the main deformity with apical and intermediate anchors without fusion. The use of intraoperative traction at the initial procedure enables spontaneous correction of the deformity and decreases the need for forceful correction maneuvers on the immature spine and prevents possible implant failures. This study seeks to evaluate (1) curve correction; (2) spinal length; (3) number of procedures performed; and (4) complications with the new approach.

DESCRIPTION OF TECHNIQUE

In the initial procedure, polyaxial pedicle screws were placed with a muscle-sparing technique. Rods were placed in situ after achieving correction with intraoperative skull-femoral traction. The most proximal and most distal screws were fixed and the rest of the screws were left with nonlocked set screws to allow vertical growth. The lengthening reoperations were performed every 6 months.

METHODS

Between 2007 and 2011, we treated 19 patients surgically for early-onset scoliosis. Of those, 16 (29%) were treated with the modified growing rod technique by the senior author (AH); an additional three patients were treated using another technique that was being studied at the time by one of the coauthors (CO); those three were not included in this study. The 16 children included nine girls and seven boys (median, 5.5 years of age; range, 4-9 years), and all had progressive scoliosis (median, 64°; range, 38°-92°). All were available for followup at a minimum of 2 years (median, 4.5 years; range, 2-6 years).

RESULTS

The initial curve Cobb angle of 64° (range, 38°-92°) improved to 21° (range, 4°-36°) and was maintained at 22° (range, 4°-36°) throughout followup. Preoperative thoracic kyphosis of 22° (range, 18°-46°) was maintained at 23° (range, 20°-39°) throughout followup without showing any substantial change. There was a 47 mm (range, 38-72 mm) increase in T1-S1 height throughout followup. The mean number of lengthening operations was 5.5 (range, 4-10). The mean T1-S1 length gain from the first lengthening was 1.18 cm (range, 1.03-2.24 cm) and decreased to 0.46 cm (range, 0,33-1.1 cm) after the fifth lengthening procedure (p = 0.009). The overall complication rate was 25% (four of 16 patients) and the procedural complication rate was 7% (seven of 102 procedures). We did not experience any rod breakages or other complications apart from two superficial wound infections managed without surgery during the treatment period. The only implant-related complications were loosening of two pedicle screws at the uppermost foundation in one patient.

CONCLUSIONS

In this preliminary study, the modified growing rod technique with apical and intermediate anchors provided satisfactory curve control, prevented progression, maintained rotational stability, and allowed continuation of trunk growth with a low implant-related complication rate.

Proximal junctional kyphosis and failure after spinal deformity surgery: a systematic review of the literature as a background to classification development

STUDY DESIGN

Systematic review of literature.

OBJECTIVE

To perform a comprehensive English language systematic literature review of proximal junctional kyphosis (PJK) and proximal junctional failure (PJF), concentrating on incidence, risk factors, health related quality of life impact, prevention strategy, and classification systems.

SUMMARY OF BACKGROUND DATA

PJK and PJF are well described clinical pathologies and are a frequent cause of revision surgery. The development of a PJK classification that correlates with clinical outcomes and guides treatment decisions and possible prevention strategies would be of significant benefit to patients and surgeons.

METHODS

The phrases "proximal junctional," "proximal junctional kyphosis," and "proximal junctional failure" were used as search terms in PubMed for all years up to 2014 to identify all articles that included at least one of these terms.

RESULTS

Fifty-three articles were identified overall. Eighteen articles assessed for risk factors. Eight studies specifically reviewed prevention strategies. There were no randomized prospective studies. There were 3 published studies that have attempted to classify PJK. The reported incidence of PJK ranged widely, from 5% to 46% in patients undergoing spinal instrumentation and fusion for adult spinal deformity. It is reported that 66% of PJK occurs within 3 months and 80% within 18 months after surgery. The reported revision rates due to PJK range from 13% to 55%. Modifiable and nonmodifiable risk factors for PJK have been characterized.

CONCLUSION

PJK and PJF affect many patients after long segment instrumentation after the correction of adult spinal deformity. The epidemiology and risk factors for the disease are well defined. A PJK and PJF scoring system may help describe the severity of disease and guide the need for revision surgery. The development and prospective validation of a PJK classification system is important considering the prevalence of the problem and its clinical and economic impact.

LEVEL OF EVIDENCE

N/A.

Smaller Interval Distractions May Reduce Chances of Growth Rod Breakage Without Impeding Desired Spinal Growth: A Finite Element Study

BACKGROUND

Growth rods allow regular distraction of the spine to compensate for growth. Traditionally such distractions are performed every 6 months via open surgery. However with the advent of minimally invasive techniques like magnetically controlled growing rods, the distractions can be performed non-surgically. This also implies that the interval of distraction could be changed or customized based on individual patient's need.

HYPOTHESIS

In this study we have hypothesized that the distraction at shorter intervals reduces the stresses on the rods which in turn reduces the chance of rod failure.

OBJECTIVE

A finite element model of a juvenile spine was instrumented with growth rods and distractions were applied at different frequencies (2 months, 3 months, 6 months, and 12 months) for a period of two years to study the effects of frequency of distraction on maximum von Mises stresses on the rods for different loading conditions were studied.

RESULTS

The stresses on the rods were highest for 12-month distraction (2 distractions in 2 years) and lowest for 2-months distraction (12 distractions in 2 years).

CONCLUSION

It was found that the shorter intervals of distraction led to reduction of stresses on the rod for same spinal height gain in two years.

Is There an Optimal Time to Distract Dual Growing Rods?

STUDY DESIGN

Retrospective multicenter observational cohort study.

OBJECTIVES

To determine whether there is a significant difference in final spinal height achieved, instrumented height, or Cobb angle related to the mean time interval between distractions of dual growing rods.

SUMMARY OF BACKGROUND DATA

Patients were prospectively enrolled in "The Treatment of Progressive Early Onset Spinal Deformities: A Multi-Center Study." Additional data were collected via a retrospective review of medical records.

METHODS

Using data from a multicenter database, the authors identified 46 patients (23 boys and 23 girls) with early-onset scoliosis who were treated with dual growing rods and who had surgical treatment spanning more than 4 years. The patients were divided into 2 groups: those who had less than 9 months (16 patients) and those who had 9 months or more (30 patients) between distractions. Standard univariate statistics were calculated. The researchers performed 2-tailed t tests. Significance was set at p = .05.

RESULTS

The differences in primary Cobb angle, T1-S1 height, and instrumented segment length at the last distraction or final arthrodesis, compared with the post-index procedure values, were not significantly different (p = .52, .58, and .60, respectively) between groups with the available data. The normalized instrumented height gains, in millimeters per year, were not significantly different (p = .22).

CONCLUSIONS

Patients with longer times between growing-rod distractions (9 or more months) had no significant differences in primary Cobb angle, T1-S1 length, or instrumented length gain compared with patients with shorter times (less than 9 months) between distractions.

The effect of serial growing rod lengthening on the sagittal profile and pelvic parameters in early-onset scoliosis

STUDY DESIGN

Retrospective case series.

OBJECTIVE

To report the effect of repeated growing rod (GR) lengthenings on the sagittal and pelvic profile in patients with early-onset scoliosis.

SUMMARY OF BACKGROUND DATA

Posterior distraction-based GRs have gained popularity as a technique for the surgical management of early-onset scoliosis. However, there are no published studies on the effect of serial GR lengthenings on sagittal balance, thoracic kyphosis (TK), lumbar lordosis (LL), and pelvic parameters.

METHODS

We retrospectively reviewed data from a multicenter early-onset scoliosis database. Forty-three patients who were able to walk with minimum 2-year follow-up who underwent single- or dual-GR surgery were included for review. Mean number of lengthenings was 6.4 (range, 3-16). Mean preoperative age was 5.6 years (standard deviation, 2.4 yr), and mean follow-up was 3.5 years. Maximum TK, LL, and sagittal balance were assessed preoperatively, after index surgery, and at the latest follow-up.

RESULTS

There was a significant decrease both in TK and LL after index surgery, which then increased during the lengthening period. There was a significant increase in both proximal junctional kyphosis and distal junctional angle. Pelvic parameters (pelvic tilt, pelvic incidence, sacral slope) were unchanged during the treatment period. Significant improvement was observed in sagittal balance. There was a correlation between the change in TK and change in LL.

CONCLUSION

TK decreased after index surgery and increased between the index surgery and the latest follow-up, which was accompanied by an increase in LL. All-screw proximal constructs had mean 9° more proximal junctional kyphosis than all-hook proximal constructs. An increase in proximal junctional kyphosis and distal junctional angle was found during the treatment period. Although there was an independent effect of number of lengthenings on TK, there was no significant detrimental effect on other sagittal spinopelvic parameters. GRs had a positive effect on sagittal vertical axis, which returned patients to a more neutral alignment through the course of treatment.

LEVEL OF EVIDENCE

4.

Recent advances in the management of early onset scoliosis

As the undesired results of early spinal fusion have become apparent, "growth-friendly" management methods for early onset scoliosis have been increasing during recent years. Current literature supports the use of repeated corrective cast applications as the initial management for most early onset progressive spinal deformities as either definitive treatment or as a temporizing measure. If casting is not an option or the deformity cannot be controlled via casting, one of the growth-friendly instrumentation techniques is chosen. Growth-friendly surgical methods and implants have been evolving as understanding of the disease improves.

Reducing radiation exposure in early-onset scoliosis surgery patients: novel use of ultrasonography to measure lengthening in magnetically-controlled growing rods

BACKGROUND CONTEXT

Magnetically-controlled growing rod (MCGR) technology has been reported for the treatment of early-onset scoliosis (EOS). Such technology allows for regular and frequent outpatient rod distractions without the need for additional surgery. However, pre- and postdistraction spine radiographs are required to verify the amount of lengthening. This increased exposure to ionizing radiation in developing children significantly increases their risk profile for radiation-induced cancer and noncancerous morbidity.

PURPOSE

This study addressed the first and novel application and reliability of the use of ultrasonography, that has no ionizing radiation exposure, as an alternative to plain radiographs in the visualizing and confirming of rod distractions.

STUDY DESIGN

A prospective study.

PATIENT SAMPLE

Six EOS patients who underwent surgical treatment with MCGRs were prospectively recruited.

OUTCOME MEASURES

Imaging measurements based on ultrasound and plain radiographs.

METHODS

All patients were imaged via ultrasound, ease of rod identification was established, and the reliability and reproducibility of optimal reference point selection assessed blindly by three individuals. The clinical algorithm, using ultrasound, was subsequently implemented. Plain radiographs served as controls.

RESULTS

Assessment of the rod's neck distance on ultrasound demonstrated a high degree of interrater reliability (a=0.99; p<.001). Intrarater reliability remained high on repeat measurements at different time intervals (a=1.00; p<.001). Satisfactory interrater reliability was noted when measuring the rod's neck (a=0.73; p=.010) and high reliability was noted in assessing the housing of the rod (a=0.85; p=.01) on plain radiographs. Under blinded conditions, 2 mm rod distraction measured on radiographs corresponded to 1.7 mm distraction on the ultrasound (standard deviation: 0.24 mm; p<.001). Subsequently, the clinical algorithm using ultrasound, instead of radiographs, has been successfully implemented.

CONCLUSIONS

This is the first study to report the use of a novel technique using noninvasive, nonionizing ultrasound to reliably document rod distractions in EOS patients. A high level of inter- and intrarater reliabilities were noted. More importantly, the use of ultrasonography may result in fewer whole spine radiographs from being taken in patients who have had MCGRs implanted for EOS; thereby decreasing their exposure to ionizing radiation and the potential risk of future radiation-induced diseases.

Anterior vertebral body tethering for idiopathic scoliosis: two-year results

STUDY DESIGN

Retrospective review.

OBJECTIVE

To report the 2-year results of the initial cohort undergoing anterior vertebral body tethering (VBT).

SUMMARY OF BACKGROUND DATA

Anterior VBT is a promising new technique with abundant preclinical studies but very few clinical results. It is a growth modulation technique, which utilizes patients' growth to attain progressive correction of their scoliosis. We report 2-year results of the initial cohort undergoing this procedure.

METHODS

After obtaining institutional review board approval, we retrospectively reviewed our first 11 consecutive patients who underwent anterior VBT with 2-year follow-up. We collected pertinent preoperative, intraoperative, and most recent clinical and radiographical data. Student t test and Fisher exact test were utilized to compare different time points.

RESULTS

Eleven patients with thoracic idiopathic scoliosis (8 females) were identified, with a mean age of 12.3 ± 1.6 years. Preoperatively, all were skeletally immature (Sanders mean = 3.4 ± 1.1; Risser mean = 0.6 ± 1.1). All underwent tethering of an average of 7.8 ± 0.9 (range: 7-9) levels, with the most proximal being T5 and the most distal L2. Preoperative thoracic Cobb angle averaged 44.2 ± 9.0° and corrected to 20.3 ± 11.0° on first erect, with progressive improvement at 2 years (Cobb angle = 13.5 ± 11.6°, % correction = 70%; P < 0.00002). Similarly, the preoperative lumbar curve of 25.1 ± 8.7° demonstrated progressive correction (first erect = 14.9 ± 4.9°, 2 yr = 7.2 ± 5.1°, % correction = 71%; P < 0.0002). Thoracic axial rotation as measured by a scoliometer went from 12.4 ± 3.3° preoperatively to 6.9 ± 3.4° at the most recent measurement (P < 0.01). No major complications were observed. As anticipated, 2 patients returned to the operating room at 2 years postoperatively for loosening of the tether to prevent overcorrection.

CONCLUSION

Anterior VBT is a promising technique for skeletally immature patients with idiopathic scoliosis. This technique can be performed safely and can result in progressive correction.

LEVEL OF EVIDENCE

4.

Bilateral rib-to-pelvis Eiffel Tower VEPTR construct for children with neuromuscular scoliosis: a preliminary report

BACKGROUND CONTEXT

Neuromuscular scoliosis could develop at a young age and progress beyond skeletal maturity. An early spinal fusion arrests growth of the spine and thorax, risking the development of secondary thoracic insufficiency syndrome. Vertical expandable prosthetic titanium rib (VEPTR) is a fusionless technique aiming at correction of the deformity with preservation of growth potential.

PURPOSE

To demonstrate the preliminary results of the use of VEPTR in an Eiffel Tower construct in children with neuromuscular scoliosis in regard to coronal and sagittal profiles, space available for the lungs (SAL), and spinal growth. The report lists the complications we faced during the follow-up of 1.33 years after the index procedure.

STUDY DESIGN

A retrospective analysis of prospectively collected data of a case series.

PATIENT SAMPLE

Twenty nonambulatory children (mean 8.9 years) with neuromuscular scoliosis. Their primary diagnoses were myelomeningocele in seven, cerebral palsy in three, spinal muscular atrophy in two, myopathies in three, arthrogryposis in one, and syndromic scoliosis in four patients.

METHODS

All 20 patients received percutaneous rib-to-pelvis VEPTR implantation. Mean operative time was 2 hours, and mean hospital stay was 12 days. None of them needed blood transfusion. They underwent 20 primary implantations and 39 lengthenings.

OUTCOME MEASURES

The patients were assessed based on physiologic measures, that is, the radiographic improvement of their scoliosis, SAL, pelvic tilt, spinal height, and sagittal and coronal decompensation.

RESULTS

At the latest follow-up, thoracolumbar curvature improved significantly (65.7°±20.5° to 49.9°±15.7°), as did lumbar curvature (61.6°±19.5° to 35°±21.2°), thoracic (17.2±2.3 to 20±2.3 cm) and lumbar spinal height (9.9±1.7 to 11.9±1.8 cm), SAL (86.5±8.9 to 97±10), pelvic obliquity (12.5°±8° to 5.2°± 5.2°), and the iliolumbar angle (15°±8° to 10.06°±7.1°). Nine patients suffered complications in the form of proximal cradle migration (five), implant breakage (five), deep wound infection (three), and dislodged iliac hooks (two).

CONCLUSIONS

Early results of VEPTR for neuromuscular scoliosis are encouraging. Follow-up till skeletal maturity will best determine future indications.

Effect of Distraction Force on Growth and Biomechanics of the Spine: A Finite Element Study on Normal Juvenile Spine With Dual Growth Rod Instrumentation

BACKGROUND

Growth rods are used to limit the progression of scoliosis without restraining the opportunity for the spine to grow. The growth is sustained by consecutive distraction at intervals of 6 months. The optimal distraction force for a scoliotic patient is not defined adequately and rod breakage, screw loosening, stimulation of growth and altered sagittal contour has been observed.

HYPOTHESIS

The hypothesis of this study is that for every patient with dual growth rods treatment there exists a distraction force that will sustain the growth of that patient's spine equal to normal growth with minimum changes in sagittal contours, results in lower von Mises stresses on the rods and minimum force at the pedicle screw-bone interface at 6 months.

OBJECTIVE

In this finite element study, we undertook an objective to identify the effect of magnitude of distraction forces on the T1-S1 growth, maximum von Mises stresses on the rods, sagittal contours, and the load at the pedicle screw-bone interface.

RESULTS

An optimal distraction force exists for which the growth is sustained with minimum stress on the rod, lower loads at screw-bone interface and unaltered sagittal contours. Another observation was that higher distraction forces (in the given range) didn't produce stresses on rod or load on screw that could result in failure of the implant.

CONCLUSION

Restoration of sagittal contour along with height restoration could guide the clinical practice, for the given range of distraction force.

VEPTR to treat nonsyndromic congenital scoliosis: a multicenter, mid-term follow-up study

BACKGROUND

Traditional surgical management of multiple congenital vertebral anomalies in young children, including fusion in situ and hemiepiphyseodesis, do not promote spinal growth nor address the associated thoracic insufficiency syndrome. We hypothesize that vertical expandable prosthetic titanium rib (VEPTR) with expansion thoracoplasty may control spinal deformity, allow spinal growth, and address thoracic insufficiency syndrome in children with nonsyndromic complex congenital spinal deformities.

METHODS

Eight pediatric spine centers prospectively entered clinical and radiographic data into a database on every congenital spinal deformity treated with VEPTR as part of an Food and Drug Administration study. We retrospectively reviewed these data and excluded patients with spina bifida, Jarcho-Levin, or other syndromes. Data analysis focused on surgical technique and expansion frequency, change in Cobb angle and thoracic heights, and adverse events for a consecutive series of patients with at least 2 years of follow-up.

RESULTS

Twenty-four children with an average age at surgery of 3.3 years (range, 1.0 to 12.5 y) were treated with VEPTR insertion and expansion thoracostomy and were followed for an average of 40.7 months (range, 25 to 78 mo). Twenty-three (95.8%) had associated rib fusions. All patients had subsequent expansion surgery; 50% had 5 or more expansions. Twenty patients (83.3%) had an improvement in Cobb angle during treatment with an average improvement of 8.9 degrees. All had an increase in thoracic height, with a mean increase of 3.41 cm. The most common adverse events were device migration in 7 patients and infection or skin problems in 6 patients.

CONCLUSIONS

VEPTR insertion with expansion thoracoplasty represents a successful treatment paradigm for nonsyndromic congenital spinal deformities. We report multicenter data with midterm follow-up of children without syndromic diagnoses, in which the vast majority had an improvement in Cobb angle and thoracic height over the treatment period. Challenges include the demands of multiple procedures, skin problems, and device migration.

LEVEL OF EVIDENCE

Level IV-prognostic study.

A novel technique for treatment of progressive scoliosis in young children using a 3-hook and 2-screw construct (H3S2) on a single sub-muscular growing rod: surgical technique

INTRODUCTION

Several different growing rod techniques have been described in the literature to treat progressive scoliosis in young children. Nevertheless, none of these techniques has shown a real superiority, and the rate of complications remains high. The purpose of this report is to describe an original fusionless method of treatment for this problem.

MATERIALS AND METHODS

The 3 hooks-2 screws (H3S2) construct consists of a single 5.5 mm titanium rod with three hooks proximally and two monoaxial pedicle screws distally, and some extra length of rod located distally and/or proximally that can be used for future lengthenings. To date, a total of 103 H3S2 constructs have been performed in our institution. This paper reports the preliminary results on 38 patients, with a minimum follow-up of 2 years.

RESULTS

This procedure was found to be effective in maintaining scoliosis correction while allowing continued spinal growth and was associated with a low rate of complications.

CONCLUSIONS

The H3S2 construct was found to have several advantages over the growing rod techniques as previously described in the literature. These include no need for post-operative bracing, fewer lengthening procedures and a lower rate of complications.

Nutritional improvement following growing rod surgery in children with early onset scoliosis

PURPOSE

We aimed to evaluate the nutritional status of children with early onset scoliosis (EOS) and to determine if treatment with growing rod instrumentation improves weight percentile.

METHODS

Data was retrospectively collected on 88 EOS patients treated with growing rods at six institutions. Mean age at surgery was 5.8 years, and mean Cobb angle was 75°. All patients were followed for at least 2 years (mean 4 years). Weights were converted to normative percentiles based on the patients' age and gender.

RESULTS

Preoperatively, 47 % (41/88) of patients were <5 percentile for weight, thus failing to thrive. There was a significant increase in mean postoperative weight percentiles at latest follow-up (p = 0.004). 49 % of patients gained weight, with a mean of 18 percentile. A significant relationship exists between age at initial surgery and percentile weight gain (p < 0.005), with children <4 years old not demonstrating postoperative improvement. This relationship was not confounded by preoperative weight, preoperative Cobb angle, or years of follow-up (p > 0.05). Children with neuromuscular and syndromic diagnoses do not appear to improve their mean nutritional status after surgery when compared to patients with idiopathic or congenital/structural scoliosis (p = 0.006).

CONCLUSION

Following growing rod treatment, there was significant improvement in nutritional status in approximately 50 % of patients, similar to that reported with VEPTR. Neuromuscular and syndromic patients did not experience nutritional improvement post-operatively. These findings support the theory that growing rods improve the clinical status of EOS patients, as nutritional improvement is one outcome of improved clinical status. The relationship between age at initial surgery and nutritional improvement is intriguing.

One-stage posterior osteotomy with short segmental fusion and dual growing rod technique for severe rigid congenital scoliosis: the preliminary clinical outcomes of a hybrid technique

STUDY DESIGN

Retrospective study.

OBJECTIVE

To evaluate the clinical outcomes of the hybrid technique of 1-stage posterior osteotomy with short segmental fusion and dual growing rod (GR) technique for severe rigid congenital scoliosis.

SUMMARY OF BACKGROUND DATA

As some types of congenital scoliosis consist of long curve including sharp deformities producing enormous asymmetric growth at apex, they cannot be well corrected with osteotomy and short segmental fusion. GR technique may be the best option. However, enormous asymmetric growth potential due to the sharp deformities at the apex will increase risk of complications, especially implant failures.

METHODS

Seven patients (2 males, 5 females) undergoing this hybrid technique for severe rigid congenital scoliosis were retrospectively reviewed. The patients' charts were reviewed. The analysis included age at initial surgery and the latest follow-up, number and frequency of lengthening, and complications. Radiographical evaluation included measured changes in scoliosis Cobb angle, thoracic kyphosis, lumbar lordosis, trunk shift, length of T1-S1, and instrumentation.

RESULTS

The mean follow-up was 53.3 (30-77) months. The mean age at the initial surgery is 5.9 (2-10) years. The averaged lengthenings were of 5.3 per patient. The mean scoliosis improved from 81.4° to 40.1° after initial surgery and was 41.0° at the latest follow-up. The average T1-S1 length was of 1.23 cm per year. The space available for lung ratio increased from 0.86 to 0.96.

CONCLUSION

Osteotomy with short fusion could help to improve the correction of the GR and eliminate the large asymmetric growth potential around the apex, with little influence to the length of the spine. Dual GR technique could maintain correction achieved at initial surgery while allowing spinal growth to continue. This hybrid technique may be an option for young patients who present sharp deformities with large asymmetric growth potential in a long congenital spinal deformity.

LEVEL OF EVIDENCE

4.

2014 Update on the 'growing spine surgery' for young children with scoliosis

PURPOSE OF REVIEW

Spinal fusion procedures that are the mainstay of the treatment of progressive or severe curves in adolescents and adults are not suitable for most young children as there is a large magnitude of remaining growth. Early spinal fusion stunts the growth of the thorax and may interfere with the development of the lungs. Therefore, in children with early-onset scoliosis, 'growth friendly' instrumentation systems have been utilized to control the deformity while allowing the growth of the spine and the thoracic cage.

RECENT FINDINGS

The experience with growing rods has been increasing, along with expanding indications. Several self-lengthening instrumentation systems have been introduced aiming for guided spinal growth. There has been considerable progress in the clinical and laboratory studies using magnetically controlled growing rod constructs. Growing rods and vertical expandable prosthetic titanium rib (VEPTR) systems provide deformity control while allowing for spinal growth along with a risk of spontaneous vertebral fusions. VEPTR may cause rib fusions as the implants overlie the thoracic cage and, therefore, the use in pure spinal deformities is controversial.

SUMMARY

There have been exciting recent advances concerning the treatment of spinal deformities in young children. Despite these advances, the surgical treatment of early-onset scoliosis remains far from optimal and more development is on the way.

Assessment of skeletal maturity in scoliosis patients to determine clinical management: a new classification scheme using distal radius and ulna radiographs

BACKGROUND

Assessment of skeletal maturity in patients with adolescent idiopathic scoliosis (AIS) is important to guide clinical management. Understanding growth peak and cessation is crucial to determine clinical observational intervals, timing to initiate or end bracing therapy, and when to instrument and fuse. The commonly used clinical or radiologic methods to assess skeletal maturity are still deficient in predicting the growth peak and cessation among adolescents, and bone age is too complicated to apply.

PURPOSE

To address these concerns, we describe a new distal radius and ulna (DRU) classification scheme to assess skeletal maturity.

STUDY DESIGN

A prospective study.

PATIENT SAMPLE

One hundred fifty young, female AIS patients with hand x-rays and no previous history of spine surgery from a single institute were assessed.

OUTCOME MEASURES

Radius and ulna plain radiographs, and various anthropomorphic parameters were assessed.

METHODS

We identified various stages of radius and ulna epiphysis maturity, which were graded as R1-R11 for the radius and U1-U9 for the ulna. The bone age, development of sexual characteristics, standing height, sitting height, arm span, radius length, and tibia length were studied prospectively at each stage of these epiphysis changes.

RESULTS

Standing height, sitting height, and arm span growth were at their peak during stages R7 (mean, 11.4 years old) and U5 (mean, 11.0 years old). The long bone growths also demonstrated a common peak at R7 and U5. Cessation of height and arm span growth was noted after stages R10 (mean, 15.6 years old) and U9 (mean, 17.3 years old).

CONCLUSIONS

The new DRU classification is a practical and easy-to-use scheme that can provide skeletal maturation status. This classification scheme provides close relationship with adolescent growth spurt and cessation of growth. This classification may have a tremendous utility in improving clinical-decision making in the conservative and operative management of scoliosis patients.

The Shilla growth guidance technique for early-onset spinal deformities at 2-year follow-up: a preliminary report

BACKGROUND

The Shilla growth guidance technique has been developed to treat spinal deformities without the necessity of repeated operative lengthenings. The dual stainless steel rods are fixed to the corrected apex of the curve by pedicle screws with limited fusion about the apex. Vertebral growth occurs in a cephalad and caudad direction through extraperiosteally placed sliding pedicle screws. A retrospective review of patients treated with the Shilla growth guidance technique for early-onset spinal deformity was performed to study patients with >2-year follow-up and describe outcome parameters.

METHODS

From a cohort of 38 patients, 10 patients with a mean age of 7 + 6 years were identified as qualifying for 2-year follow-up inclusion.

RESULTS

The average preoperative curve of 70.5 degrees was corrected to 27 degrees at 6 weeks follow-up and maintained at 2-year follow-up. The space available for lung improved an average of 13%. Truncal height (C7 to S1) increased an average of 12%. One patient required rod revision, 1 required rod change to a smaller size rod, and 1 required rod replacement. Two patients required wound debridement for low-grade infection in the early-postoperative period for a total of 5 procedures beyond the index correction. No patient had changes neurologically as a result of surgery. Patients were braced for the first 3 months postoperatively while the fusion was incorporating then not thereafter.

CONCLUSIONS

At 2-year follow-up, the Shilla procedure has allowed children correction of their spinal deformity with an acceptable complication rate and ability to grow brace free without repeated trips to the operating room for lengthenings. These patients would have had 49 scheduled lengthening procedures after their initial correction if treated by conventional distraction growing rod methods.

LEVEL OF EVIDENCE

IV case series of therapeutic study investigating results of treatment.

Early onset scoliosis: the value of serial risser casts

BACKGROUND

Treatment of early onset scoliosis (EOS) is challenging. In many cases, bracing will not be effective and growing rod surgery may be inappropriate. Serial, Risser casts may be an effective intermediate method of treatment.

METHODS

We studied 20 consecutive patients with EOS who received serial Risser casts under general anesthesia between 1999 and 2011. Analyses included diagnosis, sex, age at initial cast application, major curve severity, initial curve correction, curve magnitude at the time of treatment change or latest follow-up for those still in casts, number of casts per patient, the type of subsequent treatment, and any complications.

RESULTS

There were 8 patients with idiopathic scoliosis, 6 patients with neuromuscular scoliosis, 5 patients with syndromic scoliosis, and 1 patient with skeletal dysplasia. Fifteen patients were female and 5 were male. The mean age at first cast was 3.8±2.3 years (range, 1 to 8 y), and the mean major curve magnitude was 74±18 degrees (range, 40 to 118 degrees). After initial cast application, the major curve measured 46±14 degrees (range, 25 to 79 degrees). At treatment change or latest follow-up for those still in casts, the major curve measured 53±24 degrees (range, 13 to 112 degrees). The mean time in casts was 16.9±9.1 months (range, 4 to 35 mo). The mean number of casts per patient was 4.7±2.2 casts (range, 1 to 9 casts). At the time of this study, 7 patients had undergone growing rod surgery, 6 patients were still undergoing casting, 5 returned to bracing, and 2 have been lost to follow-up. Four patients had minor complications: 2 patients each with superficial skin irritation and cast intolerance.

CONCLUSIONS

Serial Risser casting is a safe and effective intermediate treatment for EOS. It can stabilize relatively large curves in young children and allows the child to reach a more suitable age for other forms of treatment, such as growing rods.

LEVEL OF EVIDENCE

Level IV; case series.

Growth-sparing spinal instrumentation in skeletal dysplasia

STUDY DESIGN

Retrospective case series.

OBJECTIVE

To report the outcomes of distraction-based, growth-sparing spinal instrumentation in patients with skeletal dysplasia.

SUMMARY OF BACKGROUND DATA

Patients with skeletal dysplasia with spinal deformity often undergo early fusion, further compromising an already small chest. Nonfusion techniques may provide a safe alternative and allow for thoracic growth.

METHODS

Between 2004 and 2010, 12 children with a diagnosis of various types of skeletal dysplasia underwent growth-sparing spinal instrumentation for severe spinal deformities. The mean duration of treatment with growing rods was 57 months (42-84 mo). Nine patients were treated with growing rods (8 dual, 1 single), and 3 were treated with vertical expandable prosthetic titanium rib (VEPTR; Synthes). Preoperative, initial postoperative, and final follow-up anteroposterior and lateral spine radiographs were measured for magnitude of deformity, junctional kyphosis, and implant failure.

RESULTS

The major curve Cobb angle improved from a mean of 79° preoperatively to a mean of 41° at the last follow-up (52%). There was a decrease in mean thoracic kyphosis from 77° preoperatively to 64° at final follow-up and an increase in mean lumbar lordosis from 58° preoperatively to 63° at final follow-up. The mean space available for the lungs increased by 26 mm on the concave and 24 mm on the convex side. Six patients required revision surgery for proximal junctional kyphosis. There were 4 rod failures and 6 hook and 8 screw dislodgements. One patient with vertical expandable prosthetic titanium rib had failed rib fixation that required revision.

CONCLUSION

Growth-sparing spinal instrumentation in patients with skeletal dysplasia and severe spinal deformity has a high complication and revision rate, and surgeons should closely monitor these patients. The complication rate is comparable with previous reports on patients with other diagnoses. However, deformities were well controlled, some trunk growth was achieved, and fusion surgery was delayed in all cases.

LEVEL OF EVIDENCE

4.

Proximal Junctional Kyphosis After Vertical Expandable Prosthetic Titanium Rib Insertion

STUDY DESIGN

Retrospective review of patients who had undergone vertical expandable prosthetic titanium rib (VEPTR) treatment at a single institution.

OBJECTIVES

To evaluate whether clinically significant proximal junctional kyphosis (PJK) occurs after VEPTR insertion.

SUMMARY OF BACKGROUND DATA

PJK is a potential problem after posterior spinal instrumentation and fusion. PJK after VEPTR insertion has not been well-described.

METHODS

A total of 68 patients underwent VEPTR treatment between 1999 and 2009. Diagnosis, age at time of VEPTR insertion, location of VEPTR anchors, preoperative and postoperative scoliosis, T2-T12 kyphosis and PJK, time from VEPTR insertion to development of PJK, revision procedure for significant PJK, change in PJK after the revision procedure, and PJK at final follow-up were recorded.

RESULTS

Four patients developed PJK (6%). One patient had congenital scoliosis with rib fusions, 1 had scoliosis associated with a syndrome, and 2 had neuromuscular scoliosis. Mean follow-up was 5.7 years. Average T2-T12 kyphosis and PJK before VEPTR insertion were 77° and 14°, respectively. Mean T2-T12 kyphosis and PJK after VEPTR insertion were 63° and 33°, respectively. Average T2-T12 kyphosis and PJK before the recommended revision procedure for treatment of PJK were 89° and 53°, respectively. All patients developed PJK within the first year after VEPTR insertion. Two patients underwent revision to growing rods. One of these patients had preoperative halo-gravity traction. Mean PJK in these 2 patients improved from 39° to 18° after revision and remained stable at 19° at an average follow-up of 2.9 years.

CONCLUSIONS

PJK after VEPTR insertion can occur. Patients with preoperative thoracic hyperkyphosis may be at higher risk. PJK can develop within the first year of VEPTR treatment, and can become progressive and severe enough to require complex interventions. In this small case series, patients were revised to growing rods.

Growing-rod graduates: lessons learned from ninety-nine patients who completed lengthening

BACKGROUND

Growing-rod spinal instrumentation systems are a valuable tool for managing severe early-onset scoliosis. There is little information about the end point of treatment.

METHODS

A multicenter early-onset-scoliosis database was searched to identify patients who had undergone treatment with growing rods and either had had a final operative procedure or were still being treated with the growing rods after reaching skeletal maturity (defined as fourteen years of age or older). Clinical, radiographic, and operative data were analyzed.

RESULTS

Ninety-nine patients met the inclusion criteria, and ninety-two (93%) of them had had a final operative procedure. The remaining seven patients (7%) were older than fourteen years but had not undergone a final procedure. Of the ninety-two patients who had a final procedure, seventy-nine (86%) had an instrumented fusion, nine (10%) had growing-rod exchanges and fusion in situ, three (3%) had the growing rods left in place and fusion in situ, and one (1%) had only growing-rod removal. The mean age (and standard deviation) at the final fusion was 12.4 ± 1.9 years. In forty-four (55%) of eighty patients for whom the information was available, the number of vertebral levels fused was the same as the number of vertebral levels spanned by the growing rods. The percent correction of the curve after final fusion was none or minimal (≤ 20 %) in eleven (18%) of the sixty-two patients for whom sufficient-quality radiographs were available, moderate (21% to 50%) in thirty (48%), and substantial (≥ 51 %) in nine (15%); the curve had worsened in twelve patients (19%). The mean duration of growing-rod treatment was 5.0 ± 2.6 years. Of fifty-eight operative reports made at final fusion that contained comments on spinal flexibility, eleven (19%) described the spine as being mobile, eleven (19%) described decreased flexibility, and thirty-six (62%) described the spine as being completely stiff. At final fusion, twenty-two patients (24%) had osteotomies and seven patients (8%) had a thoracoplasty.

CONCLUSIONS

Most patients underwent growing-rod removal and final instrumented fusion. The final fusion often included the same levels spanned by the growing rods and usually achieved <50% additional correction of the deformity remaining at the end of the growing-rod management.

LEVEL OF EVIDENCE

Therapeutic Level IV. See Instructions for Authors for a complete description of levels of evidence.

Finite element simulation of a scoliotic spine with periodic adjustments of an attached growing rod

Early Onset Scoliosis (EOS) is a deformity of spine which occurs during growth. Spinal growing rod instrumentation is currently a procedure of early onset scoliosis management and newer technologies to treat scoliosis without fusion hold the exciting promise of a new paradigm in spinal deformity care. A Finite Element Model (FEM) of a scoliotic spine was created and enhanced to simulate spine growth after the attachment of a growing rod. Growing rod instrumentation was included utilizing FEA to accurately simulate the required 3D forces and moments to achieve the desired correction. We measured forces on the rods and the spine during adjustment periods (for correction of the spinal deformity) and during growth periods. For this study, a two-year period was simulated with adjustments at six month intervals. The FEM allowed us to collect data during growth periods from sensors which are only accessible during the surgical procedures.

Some Connectors in Distraction-based Growing Rods Fail More Than Others

STUDY DESIGN

Retrospective review of a prospectively collected patient cohort.

OBJECTIVES

This study examined the rate of failure of various types of spinal rod connectors in distraction-based growing rod constructs for early-onset scoliosis.

SUMMARY OF BACKGROUND DATA

Distraction-based growing rods have a high rate of reported complications.

METHODS

We performed a retrospective review of a single surgeon's consecutive cases with growing rod constructs for early-onset scoliosis. Connector failure was defined as loosening of the connector-rod interface, which resulted in shortening of the construct and loss of distractive force. We included 30 patients with average age of 5 years (range, 1-10 years) with diagnoses of congenital scoliosis (15), neuromuscular (10), idiopathic (4), and other (1). Minimum follow-up was 2 years, with a mean follow-up of 49 months (range, 24-83 months).

RESULTS

Of 98 connectors, there were 12 connector failures (12.2%) in 9 patients. In all failures, the set screw loosened, resulting in rod slippage. On average, failures occurred 25.5 months after the index procedure, and after the third lengthening. Simple side-to-side closed connectors with circular slots had the highest rate of slippage (7 of 17; 41%). Side-to-side connectors with V-groove slots that mechanically lock the rod had 10 times fewer failures, (1 of 27; 4%) (p = .006). Only 1 of 34 longitudinal connectors failed (3%) (p = .002). The average T1-S1 gain during growth was 6.5 mm/year for patients with a connector failure and 9.0 mm/year for those who did not (p = .25). Connectors failed in dual rods (6 of 18; 33%) and single rods (6 of 15; 40%) at similar rates (p = .97).

CONCLUSIONS

Connector failure in distraction-based growing rods is associated with 28% less T1-S1 gain. Side-to-side connectors with circular slots had a failure rate of 41% compared with side-to-side connectors with V-groove slots (4%). Longitudinal connectors had a failure rate of 4%.

Mortality and morbidity in early-onset scoliosis surgery

STUDY DESIGN

Retrospective chart review.

OBJECTIVE

To accurately determine complication rates, particularly mortality rates, in surgically treated early-onset scoliosis.

SUMMARY OF BACKGROUND DATA

The advent of modern segmental instrumentation for spinal fusion surgery in adolescent scoliosis has allowed for application of similar nonsegmental unfused techniques aimed at controlling scoliosis in the very young child. The dismal prognosis for these children without repeated spinal lengthening procedures is unquestioned, although no controlled trials exist. Many, if not most, of these children need surgery; however, the surgical complication rate is very high.

METHODS

During the study period, all surgically treated children with early-onset scoliosis seen at our institution were identified. Any patient who presented to our clinic with early-onset scoliosis that was surgically managed was included. The total number of procedures, type of implants, number and type of complications, geographic origin of the cases, and final outcomes were all assessed.

RESULTS

A total of 165 surgical procedures on 28 patients accrued during the study time period, including index implantation of instrumentation, lengthening, and definitive fusion, as well as operations performed for complications such as wound debridement and revision of failed implants. Clinical diagnoses included congenital scoliosis, syndromic and chromosomal abnormalities, cerebral palsy, and spinal muscular atrophy. There was a complication rate of 84% overall with a mortality rate of almost 18%. The only patients with no complications were those whose entire surgical course had been at our institution only. The mortality rate was equal in patients whose treatment was performed elsewhere versus exclusively in our center.

CONCLUSION

This study underlines the grave severity of these scolioses particularly in syndromic children. The high mortality rate is alarming, suggesting that further study is needed in this area.

Serial casting as a delay tactic in the treatment of moderate-to-severe early-onset scoliosis

BACKGROUND

Serial casting can cure mild infantile idiopathic scoliosis. Its use in delaying surgery in older children and those with larger curves or syndromes is poorly defined.

METHODS

A review of a single center's experience with casting was performed. Patients were included if they had a syndromic, neuromuscular, or congenital scoliosis or were older than 2.5 years with an idiopathic scoliosis measuring >50 degrees.

RESULTS

A retrospective review was performed on 29 patients meeting all inclusion criteria. Of these, 12 were idiopathic and 17 were nonidiopathic curves. Average age at first cast was 4.4 ± 2.1 years, and 3.0 ± 1.8 cast changes were performed over 1.4 ± 1.1 years. Patients were transitioned to a brace and followed up for 5.5 years (range, 2.2 to 11.4 y). The main thoracic Cobb angle before casting was 68.8 ± 12.3 degrees, which corrected to 39.1 ± 16.4 degrees in a cast. Cobb angle after cast removal was 60.9 ± 18.4 degrees, which increased to 76.3 ± 24.0 degrees at final follow-up. T1-T12 height increased to 1.1 ± 2.6 cm during the treatment period (P=0.05). There were 5 minor complications. Fifteen patients (51.7%) required surgical treatment for their scoliosis at most recent follow-up and an additional 7 patients (24.1%) were delayed until a definitive anterior/posterior spinal fusion could be performed. Surgery was delayed 39 ± 25 months from the first cast. Growing rods were required in 8 patients (27.6%). The patients who ultimately underwent surgical intervention (SG) were more likely to have a larger postcasting residual main thoracic Cobb angle than those who did not require surgery [NS; 69.5 ± 14.6 degrees (SG) vs. 51.6 ± 17.9 degrees (NS), P=0.007] and had a greater progression of their curves after cast removal [20.9 ± 13.5 degrees (SG) vs. 9.4 ± 11.0 degrees (NS), P=0.02].

CONCLUSIONS

Serial casting is a viable alternative to surgical growth sparing techniques in moderate-to-severe early-onset scoliosis and may help delay eventual surgical intervention. Although a cure cannot be expected, an average of 39 months of delay was achieved in this patient cohort and 72.4% have avoided growing spine surgery.

LEVEL OF EVIDENCE

Level IV, case series.

Early onset scoliosis: modern treatment and results

BACKGROUND

Early onset scoliosis (EOS) is a potentially fatal, challenging group of diseases the management of which has markedly changed in the last decade. The purpose of this review is to provide the reader with a brief description of each of these new therapeutic modalities, their indications for use, and early clinical results.

METHODS

A systematic review of peer-reviewed publications and abstracts related to the treatment of EOS in the last decade was carried out and synthesized into a review of modern treatment methods.

RESULTS

Recent advances in techniques and understanding of preserving the thoracic space have improved the morbidity and mortality of children with progressive EOS. Derotational casting may be used in younger patients with curves between 25 and 60 degrees. The vertical expandable prosthetic titanium rib is best suited for patients with thoracic insufficiency syndrome. Single or dual growing rods may be used alone or in combination with vertical expandable prosthetic titanium rib to treat patients with progressive EOS who are not candidates for casting. Shilla technique is an alternative to growing rods that avoids the morbidity of repeated lengthenings but is not as well proven as the techniques described above. Other methods such as automatic growing rods and growth modulation techniques are still investigational, and their role needs to be defined after further study.

CONCLUSIONS

Recent advances have improved the treatment of children with EOS. Treatment continues to be challenging with complication rates higher than treatment of idiopathic scoliosis.

LEVEL OF EVIDENCE

Level V.

Outcome of Revision Surgery in Pediatric Spine Deformity Patients

STUDY DESIGN

Retrospective case series.

OBJECTIVES

To report the complications and outcomes of pediatric revision spine surgery and review the surgical indications and treatment methods.

BACKGROUND SUMMARY

Recent reports have shown the necessity of revision spine surgery for pediatric deformities. Many reports have shown the result of revision surgery for pediatric spinal deformity.

MATERIALS AND METHODS

We conducted a retrospective review of 638 patients with pediatric spinal deformity who were treated with surgery from 1996 to 2007. We identified 50 patients who underwent revision spinal fusion surgery with a minimum of 3 years of follow-up.

RESULTS

Mean follow-up was 4 years (range, 3-8.3 years). The diagnosis at index surgery was idiopathic scoliosis in 18 patients, congenital scoliosis in 13, neuromuscular scoliosis in 13, tumor and spinal arteriovenous malformation in 4, burst fracture in thoracic spine in 1, and Scheuermann kyphosis in 1. The primary surgeries were 1 hemi epiphysiodesis, 3 anterior spinal fusions, 4 posterior decompressions, 8 combined anterior and posterior spinal fusions, and 34 posterior spinal fusions. A total of 16 patients had pseudarthrosis, 12 decompensation, 11 progressive kyphosis, 8 crankshaft phenomenon, 2 infections, and 1 junctional degeneration. All 50 reoperations included spinal instrumentation and fusion. The revision surgeries were 2 anterior spinal fusions, 14 posterior fusions, and 34 combined anterior and posterior spinal fusions. Spine arthrodesis was obtained in 98% of patients (49 of 50) and complications occurred in 14% of patients (7 of 50). The Scoliosis Research Society Patient Questionnaire outcomes at the latest follow-up were as follows: total 3.95, function 3.88, pain 3.83, self-image 3.98, and mental health 4.04.

CONCLUSION

Pseudarthrosis was the most common indication for revision surgery, and bony union was achieved in 98% with revision surgery. Despite the complications, pediatric revision spine surgery can achieve successful outcomes.

Dual growing rods technique for congenital scoliosis: more than 2 years outcomes: preliminary results of a single center

STUDY DESIGN

Retrospective study.

OBJECTIVE

To evaluate clinical outcomes of dual growing rod (GR) technique in treating children with congenital scoliosis (CS).

SUMMARY OF BACKGROUND DATA

Published reports on the dual GR technique results of early-onset scoliosis demonstrate it to be safe and effective. However, the use of GR in congenital spinal deformities is controversial, and there have been no reports on the results and complications of dual GR technique for CS with large series of patients.

METHODS

During 2004 to 2009, a total of 30 patients with CS underwent dual GR procedures. Of the 159 total procedures conducted within the treatment period, 125 were lengthenings with an average of 4.2 lengthenings per patient. Five patients with severe rigid deformity or kyphosis had an osteotomy at apex vertebra with short segmental fusion. The analysis included age at initial surgery and final fusion (if applicable), number and frequency of lengthenings, and complications. Radiographical evaluation was conducted.

RESULTS

The mean scoliosis improved from 72.3° to 34.9° after initial surgery and was 35.2° at the last follow-up or after final fusion. T1-S1 length increased from 25.42 to 29.03 cm after initial surgery and to 33.32 cm at last follow-up or after final fusion with an average T1-S1 length increase of 1.49 cm per year. The space available for lung ratio in patients with thoracic curves improved from 0.84 to 0.96 at the latest follow-up. Three patients reached final fusion. Complications occurred in 7 of the 30 patients, and they had a total of 13 complications.

CONCLUSION

The dual GR technique is safe and effective in the treatment of selected cases of long, complex CS. It maintains correction achieved at initial surgery while allowing spinal growth to continue. And it has an acceptable rate of complications. The osteotomy at the apex vertebra with short segmental fusion of the severe rigid scoliosis or the patients with kyphosis could help to improve the correction and decrease the implant failures, with little influence on the length of the spine.

Concurrent tethered cord release and growing-rod implantation-is it safe?

Study Design Retrospective case series from one institution with a comparison control group. Objective To evaluate the safety of concomitant tethered cord release and growing-rod insertion in individuals with early onset scoliosis. Methods We retrospectively reviewed patients who underwent concurrent tethered cord release and growing-rod insertion. We compared our data to a comparison control group of eight patients who underwent staged tethered cord release and growing-rod insertion. Results We identified three patients meeting criteria. There were no neurological complications in the three patients who underwent concomitant surgery. Average immediate postoperative curve correction was 43.3 degrees (47.6%). We identified seven patients who underwent staged surgery from a multicenter prospective database. No neurological complications were reported, and average immediate postoperative correction was 35.1 degrees (46.2%). Conclusion We believe that concurrent tethered cord release and growing-rod insertion can be performed safely with the use of multimodality neurophysiological monitoring techniques.

Growing rods for the treatment of scoliosis in children with cerebral palsy: a critical assessment

STUDY DESIGN

Retrospective analysis.

OBJECTIVE

To evaluate, in children with cerebral palsy, the following aspects of growing rod (GR) treatment for scoliosis: structural effectiveness, effect of pelvic fixation, hospital stay duration, and complications.

SUMMARY OF BACKGROUND DATA

Children with cerebral palsy frequently develop severe spinal deformity and pelvic obliquity (PO). Growth-preserving strategies are attractive, but comorbidities raise the risk/benefit ratio. To our knowledge, no previous studies have focused on growth-preserving spine surgery in these children.

METHODS

From our multicenter patient group, we identified 27 children with cerebral palsy treated with GRs (single rod in 4; dual rods in 23 [15 extending to the pelvis]). We collected radiographical, surgical, hospital stay, and major complication data. We compared Cobb angle and PO improvement between patients with and without pelvic instrumentation via the Student t test (significance, P = 0.05). No patient required anterior spinal fusion.

RESULTS

Average improvements for all patients (preoperative to latest follow-up) were: Cobb angle, 35° ± 23°; PO, 14° ± 19°; T1-S1 length, 7.9 ± 4.4 cm; and space available for lung ratio, 0.17 ± 0.21. For the 8 patients who underwent fusion, average improvements (preoperative to postfusion) were: Cobb angle, 43° ± 28°; PO, 2° ± 21°; T1-S1 length, 9.5 ± 6.0 cm; and space available for lung ratio, 0.26 ± 0.28. Pelvic GR fixation produced better PO correction (P < 0.001) but similar Cobb angle correction (P = 0.556). Hospital stays averaged 8.7 ± 12.1 days after initial surgery, 1.4 ± 2.5 days after lengthening (45% were outpatient procedures), and 13.4 ± 6.2 days after fusion. The most common complication was deep wound infection (30%).

CONCLUSION

GRs via a posterior-only approach are effective. Constructs extending to the pelvis control PO more effectively. However, 30% of patients experienced deep wound infection.

Is expansion thoracoplasty a safe procedure for mobility and growth potential of the spine? Spontaneous fusion after multiple chest distractions in young children

BACKGROUND

Expansion thoracoplasty (ET) is claimed to be a spine-sparing procedure because of the fact that the spine is not exposed directly and intervention toward the spinal column is not performed. It is also recommended in cases of primary spine deformities without rib fusion/aplasia and when the primary problem is not in the thorax itself. The aim of this study was to report spontaneous spinal fusion after multiple thoracic distractions in patients with congenital thoracospinal deformities who have undergone ET in early childhood.

METHODS

In our clinic, between May 2003 and March 2010, ET treatment was started in 11 patients who had congenital spinal deformity along with thoracic asymmetry due to fused ribs. The lengthening procedures for 6 of them are still ongoing. This study includes 5 of these patients who had undergone 3-dimensional computed tomography (3D-CT) scans. Four of these patients underwent a CT scan as part of the graduation protocol and 1 was ordered a 3D-CT because a newly formed bony fusion of the ribs was observed in a lengthening procedure.

RESULTS

The mean age of the patients (4 F, 1 M) was 4.2 years (range, 2 to 8 y) at the time of the index operation. The mean number of lengthening procedures was 9.4 (range, 7 to 13). The mean follow-up period was 73 months (range, 60 to 96 mo). All 5 patients in the latest follow-up were evaluated by x-ray and 3D-CT scans of the whole spine. The CT scans confirmed spontaneous spinal fusion in the thoracic spine.

CONCLUSIONS

We speculate that distraction-based, growth-friendly instrumentations are not risk-free for spinal health and motion, even when the instrumentation is not primarily on the spine.

LEVEL OF EVIDENCE

Level IV.

An alternate method of fixation for management of early-onset deformity with thoracic kyphosis

BACKGROUND

Although methods currently used for management of early-onset scoliosis are effective, the presence of excessive thoracic kyphosis is associated with an increased instrumentation failure rate.

METHODS

An alternate method of upper thoracic fixation by using a 4-rib construct was developed by necessity when the author was presented with 2 cases of early-onset deformity with severe kyphosis and osteoporosis.

RESULTS

With a minimum 3-year follow-up, both cases have demonstrated gratifying clinical and radiographic results.

CONCLUSIONS

This method is presented as an alternate method of upper thoracic fixation when increased pullout forces secondary to thoracic kyphosis are anticipated.

LEVEL OF EVIDENCE

IV.

Advances in nonfusion techniques for the treatment of scoliosis in children

Scoliotic deformity in young children is a challenge for the spinal surgeon. Though traditional spinal correction and fusion techniques can improve these deformities, they inhibit growth of the spine. Nonfusion technologies are an effective approach to this problem. They not only correct the spinal deformity, but also allow the spine to keep growing and developing. These techniques include the growing rod, stapling, pedicle screw tethering, the vertical expandable prosthetic titanium rib (VEPTR), and multi-vertebrae wedge osteotomy. This is a review of advances in nonfusion techniques for the treatment of scoliosis in children.

Childhood spinal muscular atrophy: controversies and challenges

Spinal muscular atrophy is an autosomal recessive disorder characterised by degeneration of motor neurons in the spinal cord and is caused by mutations of the survival of motor neuron 1 gene SMN1. The severity of spinal muscular atrophy is highly variable and no cure is available at present. Consensus has been reached on several aspects of care, the availability of which can have a substantial effect on prognosis, but controversies remain. The development of standards of care for children with the disorder and the identification of promising treatment strategies have changed the natural history of spinal muscular atrophy, and the prospects are good for further improvements in function, quality of life, and survival. A long-term benefit for patients will be the development of effective interventions (such as antisense oligonucleotides), some of which are in clinical trials. The need to be prepared for clinical trials has been the impetus for a remarkable and unprecedented cooperation between clinicians, scientists, industry, government, and volunteer organisations on an international scale.

H3S2 (3 hooks, 2 screws) construct: a simple growing rod technique for early onset scoliosis

PURPOSE

The purpose of this study was to review the preliminary results of an original fusionless method of treatment for progressive scoliosis in young children.

METHODS

This study retrospectively reviewed the clinical records and radiographs of 23 children with progressive scoliosis who failed to respond to conservative treatment and underwent fusionless surgery using a single solid growing rod construct. All of them were ambulatory and had a follow-up of minimum 2 years. Sixteen patients were treated by consecutive distraction of a single intramuscular rod, and seven patients with rodding and anterior apical convex fusion. The etiology of the scoliosis included 11 idiopathic, 6 syndromic, 4 congenital, and 2 neurofibromatosis. At initial surgery, the average age was 9.3 ± 2.8 years, with a mean Cobb angle of 68° ± 32°. Six patients underwent progressive scoliosis correction in a Stagnara cast prior to surgery, and one patient with an external halo-pelvic Ilizarov device.

RESULTS

Fusionless single rodding allowed to maintain scoliosis correction in all patients. At an average of 3.5 ± 0.9 years after initial surgery, the 23 patients showed a correction of 57 % in the magnitude of the original curvature. Trunk height increase was documented in all patients and ranged from 1.5 to 11.9 cm. Rod failure was found in three patients and two patients had hardware infection. Only four cases of proximal junctional kyphosis were found at last follow-up.

CONCLUSIONS

Preliminary results from these series of patients show that the presented fusionless single growing rod technique allows to maintain correction of progressive early onset scoliosis while permitting spinal growth, with low complication rate. With this technique, lengthening procedures are used only once in every 10 months and patients are more comfortable as no brace is needed in most cases. This technique does not require any specific spine device. The procedure is simple and efficacious as long as some guidelines are respected.

Magnetically controlled growing rods for severe spinal curvature in young children: a prospective case series

BACKGROUND

Scoliosis in skeletally immature children is often treated by implantation of a rod to straighten the spine. Rods can be distracted (lengthened) as the spine grows, but patients need many invasive operations under general anaesthesia. Such operations are costly and associated with negative psychosocial outcomes. We assessed the effectiveness and safety of a new magnetically controlled growing rod (MCGR) for non-invasive outpatient distractions.

METHODS

We implanted the MCGR in five patients, two of whom have now reached 24 months' follow-up. Each patient underwent monthly outpatient distractions. We used radiography to measure the magnitude of the spinal curvature, rod distraction length, and spinal length. We assessed clinical outcome by measuring the degree of pain, function, mental health, satisfaction with treatment, and procedure-related complications.

FINDINGS

In the two patients with 24 months' follow-up, the mean degree of scoliosis, measured by Cobb angle, was 67° (SD 10°) before implantation and 29° (4°) at 24 months. Length of the instrumented segment of the spine increased by a mean of 1·9 mm (0·4 mm) with each distraction. Mean predicted versus actual rod distraction lengths were 2·3 mm (1·2 mm) versus 1·4 mm (0·7 mm) for patient 1, and 2·0 mm (0·2 mm) and 2·1 mm (0·7 mm) versus 1·9 mm (0·6 mm) and 1·7 mm (0·8 mm) for patient 2's right and left rods, respectively. Throughout follow-up, both patients had no pain, had good functional outcome, and were satisfied with the procedure. No MCGR-related complications were noted.

INTERPRETATION

The MCGR procedure can be safely and effectively used in outpatient settings, and minimises surgical scarring and psychological distress, improves quality of life, and is more cost-effective than is the traditional growing rod procedure. The technique could be used for non-invasive correction of abnormalities in other disorders.

FUNDING

Ellipse Technologies.

Vertebral body growth during growing rod instrumentation: growth preservation or stimulation?

STUDY DESIGN

Retrospective review, case series.

OBJECTIVE

Determination of whether growing rod treatment with routine lengthening every 6 months causes growth stimulation of individual vertebrae within instrumentation levels (WIL).

SUMMARY OF BACKGROUND DATA

The Hueter-Volkmann law states that distractive forces exerted upon growing physes stimulate growth and vice versa, a principle that has been in clinical use for decades. In previous studies, it has been shown that vertebral endplates might respond in a similar manner to distraction. It has been proven that fusionless instrumentation, which is the mainstay of treatment after failure of conservative measures for early-onset scoliosis, allows near-normal vertebral growth but the issue of how individual vertebrae respond to distraction has not yet been analyzed.

METHODS

This institution's database, including the radiographic data for growing rod patients, was analyzed retrospectively. Vertebral level heights within and outside instrumentation levels were measured in postindex and postfinal follow-up x-rays, and the amount of growth that has taken place in a minimum follow-up period of 2 years was calculated and then compared for statistical significance.

RESULTS

Twenty patients (6 M, 14 F, average age, 71.0 mo) met the inclusion criteria. The average follow-up was 49 months (range, 26 to 72 mo). Lengthenings were performed every 6 months regularly. The average height of vertebrae WIL was 15.9 mm (range, 10.0 to 21.1 mm) in postindex and 22.9 mm (range, 15.0 to 32.9 mm) in the final follow-up; vertebrae outside instrumentation levels was 18.1 mm (range, 13.5 to 22.1 mm) postindex and 23.3 mm (range, 14.8 to 28.8 mm) in the final follow-up. The average growth was 5.2±3.4 mm in outside instrumentation levels and 7.0±2.9 mm in WIL. These values were significantly different statistically (P<0.01).

CONCLUSIONS

Growing rod treatment performed with regular lengthenings every 6 months appears to stimulate growth in individual vertebral bodies WIL.

LEVEL OF EVIDENCE

Level IV.