Ossifications after vertical expandable prosthetic titanium rib treatment in children with thoracic insufficiency syndrome and scoliosis

Does vertebral body tethering cause disc and facet joint degeneration? A preliminary MRI study with minimum two years follow-up

BACKGROUND CONTEXT

Vertebral body tethering (VBT), a flexible compression-based growth modulation technique, was claimed to prevent disc degeneration due to its less rigid nature compared to other growth-friendly techniques. Yet, the consequences of VBT surgery on discs and facet joints have not been precisely acknowledged.

PURPOSE

The purpose of this study was to determine the changes in the intermediate and adjacent levels at least 2 years after surgery.

STUDY DESIGN/SETTING

Prospectively-followed consecutive patient cohort PATIENT SAMPLE: Adolescent idiopathic scoliosis patients who underwent thoracoscopic VBT between 2014 and 2017 were included.

OUTCOME MEASURES

Degeneration of the intervertebral discs using the Pfirrmann classification; Degeneration of facet joints using a scale of 0 to 3.

METHODS

Demographic, perioperative, clinical, radiographic data were collected. Skeletal maturity and height gain were assessed in every follow-up. Overcorrection, tether breakage, mechanical and pulmonary complications as well as readmission and reoperations were recorded. MRIs taken before surgery and at a minimum of 2 years follow-up were evaluated for degeneration at the intermediate and adjacent segment intervertebral discs and facet joints by a blinded senior radiologist and compared.

RESULTS

Twenty-five patients with a mean of 38.6±10.6 months (24-62) of follow-up were included. The mean age at surgery was 12.2 (10-14), and the median Sanders stage was 3 (1-7). A mean of 7.7±1.1 (6-11) levels were tethered. The mean preoperative main thoracic curve magnitude of 46°±7.7° was corrected to 23.3°±5.9° postoperatively, which was subsequently modulated to 12° ±11.5° during the follow-up. At the time of the MRI (mean 29±9.5 (24-62) months), the median Sanders stages was 7 (5-8). A total of 217 levels of discs and bilateral facet joints were evaluated in the preoperative and follow-up MRI images. Analyses of disc and facet scores revealed no significant differences between patients. Deterioration of previously degenerated discs was noted in one patient (from grade 2 to 3), while previously healthy lower adjacent facet joints were degenerated (grade 2) in another patient.

CONCLUSIONS

Intermediate discs and facet joints were preserved after growth modulation with VBT surgery at a mean of 29 months of follow-up. Studies in larger cohorts with longer follow-up are warranted to have more in-depth analyses of the effects of relative stabilization and altered biomechanical loads.

Smaller Intervertebral Disc Volume and More Disc Degeneration after Spinal Distraction in Scoliotic Children

In recent decades, magnetically controlled growing rods (MCGR) were established to treat progressive early-onset scoliosis. The aim of this investigation was to assess the effect of long-term MCGR with continuous distraction on intervertebral discs in scoliotic children. Magnetic resonance imaging (MRI) of 33 children with spinal muscular atrophy was analyzed by grading intervertebral disc degeneration (IDD) and measuring intervertebral disc volume. Cohort I (n = 17) were children who had continuous spinal distraction with MCGRs for 5.1 years and MRI before (av. age 8.1) and after (av. age 13.4) MCGR treatment. Cohort II (n = 16, av. age 13.7) were patients without prior surgical treatment. Lumbar intervertebral disc volume of cohort I did not change during 5.1 years of MCGR treatment, whereas disc volumes were significantly larger in age- and disease-matched children without prior treatment (cohort II). Cohort I showed more IDD after MCGR treatment in comparison to early MRI studies of the same patients and children without surgical treatment. MRI data showed a volume reduction and disc degeneration of lower thoracic and lumbar intervertebral discs in scoliotic children after continuous spinal distraction with MCGRs. These effects were confirmed in the same subjects before and after treatment as well as in surgically untreated controls.

Children With Spinal Muscular Atrophy With Prior Growth-Friendly Spinal Implants Have Better Results After Definite Spinal Fusion in Comparison to Untreated Patients

BACKGROUND

Almost all children with spinal muscular atrophy (SMA) develop a scoliosis during childhood and adolescence. In the last decades, growth-friendly spinal implants have been established as an interim solution for these patients until definite spinal fusion can be performed. The effect of those implants on the final outcome has yet to be described.

OBJECTIVE

To assess the effect of prior growth-friendly spinal surgical treatment on the outcome after spinal fusion in SMA children in comparison to untreated SMA patients through the prospective study.

METHODS

A total of 28 SMA patients with (n = 14) and without (n = 14) prior surgical treatment with growth-friendly implants were included. Average surgical treatment prior to definite spinal fusion was 4.9 yr. Scoliotic curve angle, pelvic obliquity, spinal length, kyphosis, and lordosis were evaluated for children with prior treatment and before and after dorsal spondylodesis for all children.

RESULTS

The curve angle before definite spinal fusion averaged at 104° for SMA patients without prior treatment and 71° for patients with prior treatment. Spondylodesis reduced the scoliotic curve to 50° and 33°, respectively, which equals a correction of 52% vs 54%. Pelvic obliquity could be improved by spinal fusion in all patients with better results in the pretreated group. Results for spinal length, kyphosis, and lordosis were similar in both groups.

CONCLUSION

These data show the positive effect of prior growth-friendly surgical treatment on radiographic results of spinal fusion in children with SMA. Both scoliotic curve angles and pelvic obliquity showed significantly better values when patients had growth-friendly implants before definite spinal fusion.

Radiographic Outcome and Complication Rate of 34 Graduates After Treatment With Vertical Expandable Prosthetic Titanium Rib (VEPTR): A Single Center Report

BACKGROUND

The final strategy for graduates from growth-sparing surgery is challenging. The purpose of this study was to evaluate the radiographic outcome and complications of patients with early onset scoliosis (EOS) who have graduated from vertical expandable prosthetic titanium rib (VEPTR) treatment, either undergoing final fusion surgery or following a nonfusion approach.

METHODS

Final treatment for VEPTR graduates was divided in "VEPTR in situ without final fusion," "removal of VEPTR without final fusion," and "removal of VEPTR with instrumented final fusion." Radiographic evaluations included main coronal Cobb angle and main kyphosis pre and post VEPTR implantation, at the end of implant lengthening, after final fusion (if applicable), and at latest follow-up. Complications during VEPTR treatment and in case of final fusion were reported.

RESULTS

In total, 34 VEPTR graduates were included; 17 underwent final fusion surgery, and 17 followed a nonfusion strategy. Average coronal Cobb angle before VEPTR implantation was 70±23 degrees (range, 21 to 121 degrees), and 65±22 degrees (range, 17 to 119 degrees) at latest follow-up. Average main kyphosis angle was 53±27 degrees (range, 6 to 137 degrees) before VEPTR, and 69±34 degrees (range, 10 to 150 degrees) at latest follow-up. There was a 41% complication rate with final fusion surgery.

CONCLUSIONS

There is a high complication rate during VEPTR treatment and with final fusion surgery. The stiffness of the spine and thorax allow for only limited correction when performing a final instrumented spondylodesis. Avoiding final fusion may be a viable alternative in case of good coronal and sagittal alignment.

LEVEL OF EVIDENCE

Level IV-therapeutic.

Health-related quality of life in early-onset-scoliosis patients treated with growth-friendly implants is influenced by etiology, complication rate and ambulatory ability

BACKGROUND

Progressive Early-Onset Scoliosis (EOS) in children may lead to surgical interventions with growth-friendly implants, which require repeated lengthening procedures in order to allow adequate growth. Quality of life was studied using the validated German version of the EOS-Questionnaire (EOSQ-24-G) in surgically treated EOS children with different lengthening modalities.

METHODS

EOSQ-24-G and the KINDLR questionnaire were given to families with EOS children who had been treated by either vertical expandable prosthetic titanium rib implants and repetitive lengthening surgeries every 6 months or children who had received a magnetically expansion controlled implant, which was externally lengthened every 3 months. Results were compared according to differences between the two tests, and with possible influencing factors such as surgical method, severity of scoliosis, relative improvement of curvature, etiology, weight, age, travelling distance, complications, ambulatory ability and others.

RESULTS

56 children with an average curve angle of 69° corrected to 33° (52%; average age 5.6 yrs) answered the EOSQ-24-G and the KINDLR after an average follow-up of 3.9 years. Health-related quality of life (HRQoL) was not affected by the initial scoliosis correction, the number of surgeries or the implant type. However, there was a negative correlation with non-ambulatory status, complications during treatment and for children with a neuromuscular scoliosis.

CONCLUSION

Using the validated EOSQ-24-G, no statistically significant differences were found between the group of children receiving repetitive surgeries and children with external lengthening procedures without surgery. However, results were influenced by the etiology, complication rate or ambulatory ability.

LEVEL OF EVIDENCE/CLINICAL RELEVANCE

Therapeutic Level IV.

[Surgical "no-touch" distraction technique to correct pediatric scoliosis]

OBJECTIVE

Reduction and retention of the scoliotic curve in children with progressive spinal deformities.

INDICATIONS

Progressive neuromyopathic scoliosis which cannot be controlled conservatively (especially by walking disability), and/or development of a thorax insufficiency syndrome (TIS).

CONTRAINDICATIONS

Insufficient soft tissue coverage; body weight < 11.4 kg; body mass index (BMI) > 25 or >50 kg; missing osseous anchoring structures (ribs); adult skeleton (usually age < 12 years at surgery); severe spasticity.

SURGICAL TECHNIQUE

Indirect correction and distraction of the spinal deformity by two extendable, paravertebral telescopic implants, anchored to the cranial ribs and the iliac crest; the spine is not compromised surgically.

POSTOPERATIVE MANAGEMENT

Early functional therapy, no brace; multiple surgical (VEPTR®-system) or externally (magnetically controlled rods) controlled extensions per year.

RESULTS

The surgical paravertebral "no-touch" technique for spine correction is particularly suitable for children with neuromyopathic scoliosis with a body weight > 11.4 kg. Our prospective group of children (n = 45), was treated with a combination of the classic vertical expandable prosthetic titanium rib (VEPTR®) anchored to the ribs and iliac crest combined with a magnetically controlled telescopic implant (MAGEC®). The primary correction of >50% was achieved, while progression was effectively prevented over years. In 495 outpatient lengthening procedures, the rate of implant-associated complications requiring surgery was 3.7%. Of the 45 children, 13 (29%) underwent surgical revision. With the proposed surgical "no-touch" technique for scoliosis correction of pediatric neuromyopathic deformities, an effective reduction of the scoliotic curve can be achieved and maintained. Advantages of the method are a partial retention of spinal flexibility and a reduction of spinal ossifications, which facilitates dorsal spondylodesis as the final treatment.

High Correlation Between Achieved and Expected Distraction Using Magnetically Controlled Growth Rods (MCGR) With Rib to Pelvis Fixation in Pediatric Spine Deformity

PURPOSE

Magnetically controlled implant systems have been established to treat severe progressive spinal deformity in children. The purpose of this study was to evaluate (1) the ratio between achieved and expected distraction length, (2) the complication rate and its risk factors as well as (3) the correlation of the distraction length and the length of the spine.

METHODS

A total of 40 patients with an average follow-up of 34 (14 to 57) months were prospectively included in the study. Children underwent lengthening procedures every three months. The ratio between the distraction lengths was determined by comparing the measured distraction length of the rod on radiographs with the distraction length displayed on the external remote controller for the magnetically controlled growing rod (MCGR). Age, weight, height, and complications were repeatedly recorded.

RESULTS

The analysis of 746 procedures showed the actual distraction to be 94.4% of the expected one. No difference between implants on the concave and convex spinal side was observed. The overall complication rate was 4.6% mainly because of failure of the implant or lack of implant extension, which was directly related to an increased BMI. There was also a strong correlation between achieved implant distraction length and gain in spinal length.

CONCLUSIONS

Our study demonstrates a high ratio (0.94) between achieved and expected distraction length of magnetically controlled spinal rods. The complication rate was low (4.6%) and correlated to a high BMI. The correlation between the achieved implant distraction length and spinal length indicates the efficiency of the MCGR therapy.

LEVEL OF EVIDENCE

Therapeutic Level IV.

Validation of the German version of the 24-item Early-Onset Scoliosis Questionnaire

OBJECTIVE

During childhood, early-onset scoliosis (EOS) may show severe progressive deformity, which consequently leads to aggressive treatment strategies, such as serial casting, long-term bracing, or surgical interventions. The latter usually includes repeated surgeries for implant lengthening every 6 months in order to allow sufficient growth of the thorax and spine. In 2011, the 24-item Early-Onset Scoliosis Questionnaire (EOSQ-24) was introduced to measure health-related quality of life for this patient group and their families. Since then, cross-culturally adapted versions of the EOSQ-24 have been published in Spanish, Turkish, traditional Chinese, and Norwegian. The purpose of the study was to transculturally adapt the original English version of the EOSQ-24 into the German language and evaluate the reliability of the German version.

METHODS

After adaptation and forward/backward translation, the German version of the EOSQ-24 was given to the parents or caregivers of 67 EOS patients (33 male, 34 female) Data quality was evaluated by mean, standard deviation, percentage of data missing, and extent of ceiling and floor effects. Reliability was estimated by internal consistency using Cronbach α and item-total correlations.

RESULTS

In the study group (n = 67), 12 children were either observed (n = 7) or treated with a brace (n = 5). The other 55 patients were treated surgically with growth-friendly implants. The item response to the German EOSQ-24 was high with a minimum of missing data (1.7%). All items showed very good to excellent internal consistencies (0.879-0.903). Floor effects for the 24 items were between 0% and 31% and ceiling effects between 9% and 78%. The calculated Cronbach α for the 24-item scale was 0.9003, indicating excellent reliability.

CONCLUSIONS

The German adaptation of the EOSQ-24 shows excellent reliability and therefore is a valid tool to measure objective health-related quality of life in children with EOS.

A comprehensive review of the diagnosis and management of congenital scoliosis

PURPOSE

To provide the reader with a comprehensive but concise understanding of congenital scoliosis METHODS: We have undertaken to summarize available literature on the pathophysiology, epidemiology, and management of congenital scoliosis.

RESULTS

Congenital scoliosis represents 10% of pediatric spine deformity and is a developmental error in segmentation, formation, or a combination of both leading to curvature of the spine. Treatment options are complicated by balancing growth potential with curve severity. Often associated abnormalities of cardiac, genitourinary, or intraspinal systems are concurrent and should be evaluated as part of the diagnostic work-up. Management balances the risk of progression, growth potential, lung development/function, and associated risks. Surgical treatment options involve growth-permitting systems or fusions.

CONCLUSION

Congenital scoliosis is a complex spinal problem associated with many other anomalous findings. Treatment options are diverse but enable optimization of management and care of these children.

Combining Bilateral Magnetically Controlled Implants Inserted Parallel to the Spine With Rib to Pelvis Fixation: Surgical Technique and Early Results

Spine-based fixation of magnetically controlled lengthening devices has been successfully performed for children with early-onset scoliosis. However, spinal manipulation may lead to ossifications, stiffness, and autofusion as previously described. To avoid these problems, a surgical technique combining bilateral externally controlled magnetic device implantation with a rib cradle and pelvic hook fixation was introduced by us in 2011. By using a bilateral single-rib or double-rib cradle fixation and a pelvic hook, the magnetic device is percutaneously inserted. The spine corrects indirectly without further manipulation. In small rib diameter or severe osteoporosis, double-rib cradles are used. Our introduced technique enables modification of the rib vertebral angle, which may be beneficial in children with spinal muscular atrophy and rib-cage deformity. This nonrandomized prospective study describes 18 children with neuromuscular scoliosis treated first by this method. All patients followed the same protocol, with expansion procedures being performed 5 months after surgery and every 3 months thereafter. Clinical, radiologic, and complication data were analyzed, showing a significant reduction in scoliosis and pelvic obliquity and an increase in spinal length, which could be maintained over a follow-up period of 1.2 years. The overall complication rate was lower than previously described, with 8%, 2 of them requiring surgery.

Early-onset Scoliosis: Contemporary Decision-making and Treatment Options

Early-onset scoliosis (EOS) describes a wide array of diagnoses and deformities exposed to growth. This potentially life-threatening condition is still 1 of the biggest challenges in pediatric orthopaedics. The enlightenment of Bob Campbell's thoracic insufficiency syndrome concept and the negative impact of the earlier short and straight spine fusion approach on respiratory function and survival have fueled the evolution of EOS care. Despite all the progress made, growth-friendly spine surgery remains to be a burden to patients and caregivers. Even down-sized implants and remote-controlled noninvasive rod expansions do not omit unexpected returns to the operating room: failures of foundations, rod breakage, difficulties to keep the sagittal balance, progressive transverse plane deformities, stiffening, and the need for final instrumented fusion are still common. However, past experience and the current multitude of surgical strategies and implants have sharpened the decision-making process, patients with thoracic insufficiency syndrome require earliest possible vertical expandable prosthetic titanium ribs application. Flexible deformities below 60 degrees, with normal spinal anatomy and without thoracic involvement, benefit from serial Mehta casting which revived as a long available but not-used strategy. In case of progression, standard double growing rods or-if available, affordable, and applicable-magnetically controlled motorized rods provide deformity control and growth promotion. Shilla growth-guiding technique is a less costly alternative. Its lack of stiff lengthening boxes or actuators may be beneficial in difficult deformities. Anterior convex flexible tethering promises benefits of sparing the trunk muscles and keeping mobility. However, this step towards a true nonfusion concept has yet to stand the test of broad clinical application.

Spinal deformity changes in children with long-term vertical expandable prosthetic titanium rib treatment

BACKGROUND CONTEXT

In several studies, vertical expandable prosthetic titanium rib (VEPTR) implants have shown good scoliosis control in children with the longest reported follow-up of 3.6 years. For growing rods, recent studies suggest a decreased efficiency of correction starting just after that time. To our knowledge, no long-term results of children with VEPTR treatment are available.

PURPOSE

This study aimed to evaluate spinal deformity in scoliotic children and to investigate correction potential of VEPTR implants at several time points of treatment, particularly after long-term follow-up.

STUDY DESIGN/SETTING

We performed a retrospective case series of 32 children with spinal deformity and VEPTR treatment with analysis of clinical and radiological data pre- and post-VEPTR implantation and every 2 years during the follow-up period.

PATIENT SAMPLE

Thirty-two patients with spinal deformity and VEPTR treatment comprised the patient sample.

OUTCOME MEASURES

Patients had a primary VEPTR implantation due to spinal deformity and thoracic insufficiency syndrome and repeated lengthening procedures every 6 months. Clinical data were assessed and radiological parameters were analyzed. The main thoracic scoliotic curve and associated curves as well as kyphosis, lordosis, pelvic obliquity, and spinal length were measured in all radiographs until the end of VEPTR treatment or the last available examination.

METHODS

Development of the different parameters during follow-up was evaluated and statistical analysis was performed with Statistica version 13.0. No funding was obtained for this study. The authors have no conflicts of interest to declare.

RESULTS

Directly after VEPTR implantation, thoracic and lumbar curves corrected significantly, were stable at 2.8-year follow-up, and increased at 5.5-year follow-up, whereas cervical scoliosis was not affected by the treatment. The sagittal profile was initially improved both in kyphosis and lordosis. However, at 5.5-year follow-up, hyperkyphosis had deteriorated beyond the initial deformity. Pelvic obliquity was significantly restored especially in neuromuscular patients, and increasing spinal length was achieved within the 5.5-year follow-up.

CONCLUSION

In children with spinal deformity, implantation of the VEPTR device sufficiently corrected the deformity in all planes. During long-term follow-up, scoliosis increased slightly and was rather well controlled, whereas the implant system was not able to prevent deterioration of hyperkyphosis. Pelvic obliquity was well balanced and spinal lengthening was achieved during long-term follow-up.

Use of a Vertical Expandable Prosthetic Titanium Rib in Children With Thoracic Insufficiency Syndrome and Scoliosis

Thoracic insufficiency syndrome is the inability of the thorax to support normal respiration or lung growth. One treatment to address the thoracic deformities associated with the syndrome is placement of a vertical expandable prosthetic titanium rib. The goal is to restore thoracic volume, symmetry, and function and to allow for growth of the thorax in skeletally immature children. The main topics include indications for placement of a titanium rib, postoperative nursing care, potential complications, long-term follow-up, quality-of-life issues, and implications for critical care nurses and advanced practice nurses.

Magnetically Controlled Devices Parallel to the Spine in Children with Spinal Muscular Atrophy

Background:

Children with severe spinal deformity frequently are managed with growth-friendly implants. After initial surgery, externally controlled magnetic rods allow spinal deformity correction during growth without further surgical intervention. The ability to lengthen the spine without additional surgical procedures is especially beneficial in high-risk children, such as those with spinal muscular atrophy (SMA). The purpose of the present study was to assess the level of control of spinal deformity in a homogeneous group of patients with SMA who were managed with magnetically controlled implants for 2 years.

Methods:

This prospective, nonrandomized study included 21 non-ambulatory children with type-II SMA and progressive scoliosis who were managed bilaterally with a magnetically controlled implant that was inserted parallel to the spine with use of rib-to-pelvis hook fixation. Radiographic measurements of scoliotic curves, kyphosis, lordosis, pelvic obliquity, and spinal length were performed before and after implantation of the magnetically controlled device and during external lengthening. The mean duration of follow-up was 2 years.

Results:

The mean main curve of patients without prior vertical expandable prosthetic titanium rib (VEPTR) treatment decreased from 70° before implantation of the magnetically controlled device to 30° after implantation of the device. Correction was maintained during the follow-up period, with a mean curve of 31° at the time of the latest follow-up at 2.2 years. Pelvic obliquity was surgically corrected by 76% (from 17° to 4°) and remained stable during follow-up. Thoracic kyphosis could not be corrected within the follow-up period. Spinal length of children without prior spinal surgery increased by >50 mm immediately after device implantation and steadily increased at a rate of 13.5 mm/yr over the course of treatment. During treatment, 4 general complications occurred and 6 lengthening procedures failed, with 3 patients requiring surgical revision.

Conclusions:

Bilateral implantation of an externally controlled magnetic rod with rib-to-pelvis fixation represents a safe and efficient method to control spinal deformity in children with SMA, achieving sufficient and stable curve correction as well as increased spinal length. The complication rate was lower than those that have been described for VEPTR and other growing rod instrumentation strategies.

Level of Evidence:

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

Biomechanical Evaluation of a Growth-Friendly Rod Construct

BACKGROUND

Distraction-type rods mechanically stabilize the thorax and improve lung growth and function by applying distraction forces at the rib, spine, pelvis, or a combination of locations. However, the amount of stability the rods provide and the amount the thorax needs is unknown.

METHODS

Five freshly frozen and thawed cadaveric thoracic spine specimens were tested for lateral bending, flexion/extension, and axial rotation in displacement control (1°/sec) to a load limit of ±5 Nm for five cycles after which a growth-friendly unilateral rod was placed in a simulated rib-to-lumbar attachment along the right side. The specimens were tested again in the same modes of bending. From the seven Optotrak Orthopedic Research Pin markers (Northern Digital Inc., Waterloo, Ontario, Canada) inserted into the top potting to denote T1, and the right pedicles at T2, T4, T5, T8, T9, and T11 and the Standard Needle Tip Pressure Transducers (Gaeltech, Isle of Skye, Scotland) inserted into the T4/T5 and T8/T9 discs, motion, stiffness, and pressure data were calculated. Parameters from the third cycle of the intact case and the construct case were compared using two-tailed paired t tests with 0.05 as the level of significance.

RESULTS

With the construct attached, the T1-T4 segment showed a 30% increase in neutral zone stiffness during extension (p = .001); the T8-T12 segment experienced a 63% reduction in the in-plane range of motion during flexion (p = .04); and the T8/T9 spinal motion unit had a significant decrease of 24% in elastic zone stiffness during left axial rotation (p = .04).

CONCLUSIONS

It is clear the device as tested here does not produce large biomechanical changes, but the balance between providing desired changes while preventing complications remains difficult.

Metamorphosis of human lumbar vertebrae induced by VEPTR growth modulation and stress shielding

INTRODUCTION

Distraction-based spinal growth modulation by growing rods or vertical expandable prosthetic titanium ribs (VEPTRs) is the mainstay of instrumented operative strategies to correct early onset spinal deformities. In order to objectify the benefits, it has become common sense to measure the gain in spine height by assessing T1-S1 distance on anteroposterior (AP) radiographs. However, by ignoring growth changes on vertebral levels and by limiting measurement to one plane, valuable data is missed regarding the three-dimensional (3D) effects of growth modulation. This information might be interesting when it comes to final fusion or, even more so, when the protective growing implants are removed and the spine re-exposed to physiologic forces at the end of growth.

METHODS

The goal of this retrospective radiographic study was to assess the growth modulating impact of year-long, distraction-based VEPTR treatment on the morphology of single vertebral bodies. We digitally measured lumbar vertebral body height (VBH) and upper endplate depth (VBD) at the time of the index procedure and at follow-up in nine patients with rib-to-ileum constructs (G1) spanning an anatomically normal lumbar spine. Nine patients with congenital thoracic scoliosis and VEPTR rib-to-rib constructs, but uninstrumented lumbar spines, served as controls (G2). All had undergone more than eight half-yearly VEPTR expansions. A Wilcoxon signed-rank test was used for statistical comparison of initial and follow-up VBH, VBD and height/depth (H/D) ratio (significance level 0.05).

RESULTS

The average age was 7.1 years (G1) and 5.2 year (G2, p > 0.05) at initial surgery; the average overall follow-up time was 5.5 years (p = 1). In both groups, VBH increased significantly without a significant intergroup difference. Group 1 did not show significant growth in depth, whereas VBD increased significantly in the control group. As a consequence, the H/D ratio increased significantly in group 1 whereas it remained unchanged in group 2. The growth rate for height in mm/year was 1.4 (group 1) and 1.1 (group 2, p = 0.45), and for depth, it was -0.3 and 1.1 (p < 0.05), respectively.

CONCLUSIONS

VEPTR growth modulating treatment alters the geometry of vertebral bodies by increasing the H/D ratio. We hypothesize that the implant-related deprivation from axial loads (stress-shielding) impairs anteroposterior growth. The biomechanical consequence of such slender vertebrae when exposed to unprotected loads in case of definitive VEPTR removal at the end of growth is uncertain.

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.

Pulmonary and Radiographic Outcomes of VEPTR (Vertical Expandable Prosthetic Titanium Rib) Treatment in Early-Onset Scoliosis

BACKGROUND

VEPTR (vertical expandable prosthetic titanium rib) expansion thoracoplasty is used to manage thoracic insufficiency syndrome in early-onset scoliosis. Literature regarding the effects of this technique on pulmonary function is scarce. The aim of this study was to report the intermediate-term results of VEPTR expansion thoracoplasty.

METHODS

Twenty-one children with thoracic insufficiency syndrome underwent VEPTR expansion thoracoplasty from 2002 to 2012 and had complete chart data, preoperative and follow-up radiographs, and pulmonary function tests performed at the index implantation, first expansion, and last expansion. Pulmonary function tests with forced and passive deflation techniques developed for children under general anesthesia were performed prior to the index implantation and each expansion surgery under the same anesthetic conditions. Pulmonary and radiographic parameters were analyzed longitudinally.

RESULTS

Mean follow-up was six years, and mean age at implantation was 4.8 years. The mean number of expansion procedures per patient was eleven, and the mean number of pulmonary function tests was ten. The mean interval between surgical procedures was 6.4 months. Mean forced vital capacity (FVC) increased from 0.65 to 0.96 L (p < 0.0001). However, the percentage of the predicted FVC decreased from 77% to 58%. Respiratory system compliance normalized on the basis of body weight, Crs/kg, decreased by 39%, from 1.4 to 0.86 mL/cm H₂O/kg. The mean Cobb angle before treatment was 80°, and the mean maximum thoracic kyphosis angle was 57° (range, 7° to 107°). The initial coronal correction was maintained at the time of final follow-up (67°); however, there was a trend toward a decrease in the maximum thoracic kyphosis angle (to 66°, p = 0.08). Clinically apparent proximal thoracic kyphosis occurred in four patients, and spinal imbalance occurred in seven. The mean gain in T1-T12 height during the treatment period was 18 mm (2.9 mm/year).

CONCLUSIONS

FVC improved over time; however, this increase in lung volume did not keep up with the growth of the child, as the percentage of the predicted FVC decreased, and the chest wall stiffness increased. Coronal correction was maintained, but the increase in proximal thoracic kyphosis is concerning.

LEVEL OF EVIDENCE

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

Extraspinal ossifications after implantation of vertical expandable prosthetic titanium ribs (VEPTRs)

INTRODUCTION

Though developed for thoracic insufficiency syndrome, the spinal growth-stimulating potential and the ease of placement of vertical expandable titanium ribs (VEPTRs) has resulted in their widespread use for early-onset spine deformity. Observation of implant-related ossifications warrants further assessment, since they may be detrimental to the function-preserving non-fusion strategy.

PATIENTS AND METHODS

Radiographs (obtained pre and post index procedure, and at 4-year follow-up) and the records of 65 VEPTR patients from four paediatric spine centres were analysed. Ossifications were classified as type I (at anchor points), type II (along the central part) or type III (re-ossification after thoracostomy).

RESULTS

The average age at the index procedure was 6.5 years (min 1, max 13.7). The most prevalent spine problem was congenital scoliosis (37) with rib fusions (34), followed by neuromuscular and syndromic deformities (13 and 8, respectively). Idiopathic and secondary scoliosis (e.g. after thoracotomy) were less frequent (3 and 4, respectively). Forty-two of the 65 (65 %) patients showed ossifications, half of which were around the anchors. Forty-five percent (15/33) without pre-existing rib fusions developed a type II ossification along the implant. Re-ossifications of thoracostomies were less frequent (5/34, 15 %). The occurrence of ossifications was not associated with patient-specific factors.

CONCLUSIONS

Implant-related ossifications around VEPTR are common. In contrast to harmless bone formation around anchors, ossifications around the telescopic part and the rod section are troublesome in view of their possible negative impact on chest cage compliance and spinal mobility. This potential side effect needs to be considered during implant selection, particularly in patients with originally normal thoracic and spinal anatomy.

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.