Early onset scoliosis: modern treatment and results

Spinal height for growth guidance treatment in early onset idiopathic scoliosis: analysis through final surgical treatment

BACKGROUND

The growth guidance (GG) method for treatment of early onset scoliosis has as its primary goal the restoration of apical spinal alignment, facilitating normal spinal growth to achieve a suitable adult thoracic height.

PURPOSE

To evaluate whether GG surgical treatment achieves comparable thoracic and spinal height to distraction-based treatment (DBT) in idiopathic early onset scoliosis (I-EOS) patients. We hypothesized that GG would prove superior to DBT at the time of definitive fusion surgery.

METHODS

All I-EOS patients who underwent GG at a single center were reviewed. T1-L1 and T1-S1 heights were measured using the traditional coronal method as well as the Halifax sagittal spinal length (SSL) technique. The same measurements were obtained from a comparable control group obtained from a multi-center pediatric early onset scoliosis database who underwent treatment with traditional growing rods (TGR) or magnetically controlled growing rods (MCGR).

RESULTS

Of the I-EOS patients who underwent GG 2004-2019, 15 patients underwent final fusion after GG completion, with a mean 5.5 years of GG treatment prior to fusion (range 2.0-11.4 years). Mean age at GG implantation was 8.4 years (range 2.0-11.7 years); 7 were male and 8 female. GG patients experienced a mean coronal thoracic height increase of 6.2 cm during treatment through final fusion, and a mean coronal spinal height increase of 8.8 cm. At the time of final fusion, GG patients achieved greater significant mean increases than DBT patients by 2.9 cm in coronal thoracic height (p = 0.0023), 4.5 cm in coronal spinal height (p = 0.001), and 4.0 cm in SSL spinal height (p = 0.01). No GG patient concluded treatment with a thoracic height less than 18 cm in either coronal or sagittal plane.

CONCLUSIONS

Not only did 100% of GG patients reach minimum thoracic height of 18 cm at time of final fusion, but GG also proved to be superior to distraction-based constructs in a comparison cohort on 3 of 4 spinal elongation measures.

LEVEL OF EVIDENCE

3.

Automated Method for Growing Rod Length Measurement on Ultrasound Images in Children With Early Onset Scoliosis

OBJECTIVE

To develop and validate machine learning algorithms to automatically extract the rod length of the magnetically controlled growing rod from ultrasound images (US) in a pilot study.

METHODS

Two machine-learning (ML) models, called the "Boundary model" and "Rod model," were developed to identify specific rod segments on ultrasound images. The models were developed utilizing Mask Regional Convolutional Neural Networks (Mask RCNN). Ninety US images were acquired from 23 participants who had early onset scoliosis (EOS) surgeries; among those, 70 were used for model development, including training and validation, and 20 were used for testing by comparing the AI-based vs. manual measurements.

RESULTS

The average precision (AP) of the ML models was 88.5% and 60.2%, respectively. The inter-method correlation coefficient (ICC) was 0.98, and the mean absolute difference ± standard deviation (MAD ± SD) between AI and manual measurements was 0.86 ± 1.0 mm. The Bland-Altman analysis showed no bias, and 90% of the data were within the 95% confidence interval. The automated method was reliable, accurate, and fast. Measurements were displayed in 4.6 seconds after the US image was inputted.

CONCLUSION

This was the first AI-based method to measure the MCGR rod length on US images automatically.

How will early onset scoliosis surgery affect my child's future as a young adult? A follow-up study using patient-reported outcome measures

PURPOSE

Using patient-reported outcome measures (PROMs), this study was undertaken to determine how well patients with early onset scoliosis (EOS) fare in adulthood.

METHODS

Among eight healthcare centers, 272 patients (≥ 18 years) surgically managed for EOS (≥ 5 years) completed the Scoliosis Research Society (SRS)-22r, Functional Assessment of Chronic Illness Therapy-10 (FACIT-Dyspnea-10), and Short Form (SF)-12. Functional and demographic data were collected.

RESULTS

The response rate was 40% (108/272). EOS etiologies were congenital (45%), neuromuscular (20%), idiopathic (20%) syndromic (11%), and unknown (4%). All patients scored within normal limits on the FACIT-Dyspnea-10 pulmonary (no breathing aids, 78%; no oxygen, 92%). SF-12 physical health scores and most SRS-22r domains were significantly decreased (p < 0.05 and p < 0.001, respectively) compared with normative values. SF-12 and SRS-22r mental health scores (MHS) were lower than normative values (p < 0.05 and p < 0.02, respectively). Physical health PROMs varied between etiologies. Treatment varied by etiology. Patients with congenital EOS were half as likely to undergo definitive fusion. There was no difference between EOS etiologies in SF-12 MHS, with t scores being slightly lower than normative peers.

CONCLUSION

Good long-term physical and social function and patient-reported quality of life were noted in surgically managed patients. Patients with idiopathic EOS physically outperformed those with other etiologies in objective and PROM categories but had similar MHS PROMs. Compared to normative values, EOS patients demonstrated decreased long-term physical capacity, slightly lower MHS, and preserved cardiopulmonary function.

LEVEL OF EVIDENCE

Level IV Case Series.

Magnetically Controlled Growing Rods Graduation: Lessons From a Single-center Series of 48 Patients

BACKGROUND

Magnetically controlled growing rod (MCGR) treatment for early-onset scoliosis (EOS) has become a widely utilized method of deformity control, but long-term follow-up reports are sparse. We evaluated the outcomes of a large group of consecutive pediatric patients diagnosed with EOS who were treated by MCGR to the endpoint of definitive spinal fusion in a single center. We hypothesized that lessons learned from treating a large volume of MCGR patients would lower the complication rate in comparison to what was previously reported by other studies.

METHODS

The records of 48 EOS patients with varied etiologies who were treated by MCGR between 2012 and 2022 and reached the end of treatment were analyzed retrospectively for baseline and final radiographic measurements and surgery-related complications.

RESULTS

The mean percent of improvement in the major coronal deformity was 51.7±25.0% and the mean T1 to T12 total growth was 52.9±21.9 mm. The total complication rate was 22.9% of which 12.5% required a single unplanned surgery, 6.3% required multiple unplanned surgeries, and 4% did not require any unplanned surgery.

CONCLUSION

MCGR treatment provides adequate control of EOS, enabling satisfactory growth of the thoracic spine. The complication rate in a single large volume center is moderate.

LEVEL OF EVIDENCE

IV.

Implant-Related Complications Do Not Interfere with Corrections with the Shilla Technique in Early Onset Scoliosis: Preliminary Results

Growth-preservation techniques are utilized in early onset scoliosis (EOS) cases requiring surgical intervention. The Shilla technique corrects the deformity by reducing additional surgeries with its growth-guidance effect. As with other techniques, various problems can be encountered following the administration of the Shilla technique. The aim of this study was to examine the effect of complications encountered with the Shilla treatment on correction and growth. Sixteen patients with a follow-up period of at least one year after receiving Shilla growth guidance for EOS were included in this retrospective study. No complications occurred, and no unplanned surgery was required in 50% of the cases. Of the remaining eight patients with postoperative implant-related complications (50%), six (37.5%) required unplanned surgery; this consequently caused implant failure in the proximal region in five cases (31.25%) and deep tissue infection around the implant in one case (6.25%). Deformity correction, spine length, and quality-of-life scores significantly improved in EOS through Shilla growth guidance. In terms of spinal growth and deformity correction, there were no significant differences between patients with implant-related problems and individuals without occurrences. Although implant-related problems were detected in our dataset and corresponding unexpected surgeries were necessary, these complications had no significant unfavorable influence on correction and spine growth.

Physician collections are 71% less for early onset scoliosis casting than for growing rod instrumentation: A retrospective cohort study

Growing rod (GR) instrumentation and the elongation, derotation, and flexion (EDF) casting technique are 2 alternatives for the treatment of early-onset scoliosis. Our purpose was to investigate the cost of these treatment options. This was a retrospective cohort study of patients with early-onset scoliosis treated at 2 institutions from 2007 to 2014 with either GR instrumentation or EDF casting. Patients with <2 years of follow-up were excluded. Physician and hospital charges and collections, total procedures, and procedure times until final follow-up or time of fusion were compared. Nineteen patients met the inclusion criteria; 8 in the GR group and 11 in the EDF casting group. There were no significant differences between the groups in age (P = .23), public versus private insurance (P = 1.0), or major curve (P = .21) at the initiation of treatment. Excluding final fusion, the EDF casting patients had an average of 2.1 (range: 0.7-6.6) procedures/year while the GR patients had an average of 1.5 (range: 0.8-2.7) procedures/year. The average procedure time for the EDF group was 104.2 minutes; the average procedure time for the GR group, excluding the index procedure, was 62.40 minutes (P = .001). Physician charges were 85% less for the EDF group (EDF= $1892.75, GR= $12,354.53, P < .001). Physician collections were 71% less for the EDF group (EDF= $731.10, GR= $2554.88, P = .001). Hospital charges and collections were similar between the groups (P = .82, P = .42). Physician charges for casting were approximately 18% of that of GRs. Compared to GRs, physician collections were 71% less for EDF casting patients per year.

Modified Clavien-Dindo-Sink system is reliable for classifying complications following surgical treatment of early-onset scoliosis

PURPOSE

Appropriately measuring and classifying surgical complications is a critical component of research in vulnerable populations, including children with early-onset scoliosis (EOS). The purpose of this study was to assess the inter- and intra-rater reliability of a modified Clavien-Dindo-Sink system (CDS) classification system for EOS patients among a group of pediatric spinal deformity surgeons.

METHODS

Thirty case scenarios were developed and presented to experienced surgeons in an international spine study group. For each case, surgeons were asked to select a level of severity based on the modified CDS system to assess inter-rater reliability. The survey was administered on two occasions to allow for assessment of intra-rater reliability. Weighted Kappa values were calculated, with 0.61 to 0.80 considered substantial agreement and 0.81 to 1.00 considered nearly perfect agreement.

RESULTS

11/12 (91.7%) surgeons completed the first-round survey and 8/12 (66.7%) completed the second. Inter-observer weighted kappa values for the first and second survey were 0.75 [95% CI 0.56-0.94], indicating substantial agreement, and 0.84 [95% CI 0.70-0.98], indicating nearly perfect agreement, respectively. Intra-observer reliability was 0.86 (range 0.74-0.95) between the first and second surveys, indicating nearly perfect agreement .

CONCLUSION

The modified CDS classification system demonstrated substantial to nearly perfect agreement between and within observers for the evaluation of complications following the surgical treatment of EOS patients. Adoption of this reliable classification system as a standard for reporting complications in EOS patients can be a valuable tool for future research endeavors, as we seek to ultimately improve surgical practices and patient outcomes.

LEVEL OF EVIDENCE

Level V.

Reduced complication rate with simultaneous detethering and spinal deformity correction surgery compared to staged surgeries in patients with early onset scoliosis

PURPOSE

In patients with early onset scoliosis (EOS) and intraspinal anomalies, surgery may be necessary for both the tethered spinal cord (TSC) and spinal deformity. The purpose of this study was to determine if there is a difference in complications when TSC release and surgery for spinal deformity correction (SDC) are performed separately compared simultaneously.

METHODS

EOS patients with TSC who underwent detethering and SDC surgeries were identified through a multicenter registry. Patients were stratified into two groups. The simultaneous cohort consisted of patients receiving both detethering and SDC surgeries in a single anesthetic event on the same day, and the staged cohort consisted of patients undergoing detethering and SDC on two separate occasions. Postoperative complications up to 180 days for either surgery were assessed.

RESULTS

Twenty five (65.8%) patients were staged and 13 (34.2%) underwent a simultaneous approach. Percent curve correction following SDC surgery did not significantly differ between the groups (p = 0.36). Within 90 days postoperatively, 16 complications in 11 patients (44.0%) occurred in the staged group, whereas no complications occurred in the simultaneous cohort (p = 0.006). From 90-days to 180-days postoperatively, 4 additional complications in 3 patients (12.0%) occurred in the staged group, with no complications reported in the same timeframe for the simultaneous cohort.

CONCLUSION

To our knowledge, this is the largest multicenter comparative study to date, and it suggests that a simultaneous approach can be performed safely for EOS patients undergoing detethering and SDC surgeries, with a potentially lower risk profile than the traditional staged approach to these pathologies.

LEVEL OF EVIDENCE

Level III.

A Modified Self-Growing Rod Technique for Treatment of Early-Onset Scoliosis

Surgical treatment of early-onset scoliosis (EOS) remains challenging as no definitive surgical technique has emerged as the single best option in this varied patient population^1-3. Although the available surgical techniques may differ substantially, they all share the same goals of achieving and maintaining deformity correction, allowing physiological spinal growth, and reducing the number of operations and complications. Herein, we present a modified self-growing rod technique that represents a valid alternative to the existing surgical procedures for EOS.

Description

The patient is positioned prone on a radiolucent table, and the spine is prepared and draped in a standard fashion. A posterior midline skin incision is made from the upper to the lower instrumented level. Subperiosteal exposure of the spine is carried out, ensuring that capsules of the facet joints are spared. Pedicle screws are inserted bilaterally at the cranial and caudal ends of the instrumentation. Fixation with pedicle screws of at least 3 levels at the top and bottom end is usually advised; in nonambulatory patients with pelvic obliquity, caudal fixation can be extended to the pelvis with bilateral iliac screws. Sublaminar wires are positioned bilaterally at every level between the cranial and caudal ends of the instrumentation and are passed as medially as possible to avoid damage to the facet joints. Four 5-mm cobalt-chromium rods are cut, contoured, and inserted at each end of the construct. Ipsilateral rods are secured with use of sublaminar wires, making sure that they overlap over a sufficient length to allow for the remaining spinal growth. Correction of the deformity is achieved with use of a combination of cantilever maneuvers and apical translation by progressive and sequential tightening of the sublaminar wires. The wound is closed in layers over a subfascial drain. The patient is allowed free mobilization after surgery. No postoperative brace is required.

Alternatives

Nonoperative alternative treatment for EOS includes serial cast immobilization and bracing⁴. Alternative surgical treatments include traditional growing rods⁵, magnetically controlled growing rods⁶, the vertical expandable prosthetic titanium rib-expansion technique⁷, and the Shilla technique⁸. The use of compression-based systems (i.e., staples or tether)⁹ or early limited fusion has also been reported by other authors.

Rationale

The main advantage of our technique is that it relies on physiological spinal growth and does not require surgery or external devices for rod lengthening, which is particularly beneficial in frail patients with a neuromuscular disease in whom repeated surgery is not advised. Segmental fixation by sublaminar wires allows good control of the deformity apex during growth. Concerns regarding early fusion of the spine have not been confirmed in our mid-term follow-up study¹⁰.

Expected Outcomes

This technique allows correction of the deformity and continuous spinal growth in the years following surgery. At 6.0 years postoperatively, the average main curve correction was reported to be 61% and the average pelvic obliquity correction was 69%. The spine was reported to lengthen an average of 40.9 mm (range, 14.0 to 84.0 mm) immediately postoperatively, and the T1-S1 segment was reported to continue growing at 10.5 mm/year (range, 3.6 to 16.5 mm/year) thereafter¹⁰. The most common complication is rod breakage at the thoracolumbar junction, which seems to be more common in patients with idiopathic or cerebral palsy EOS and during the pubertal growth spurt¹⁰.

Important Tips

Subperiosteal exposure of the spine should be carried out, making sure to preserve facet joints in the unfused area of the spine.Achieve segmental fixation with use of sublaminar wires at every level and pedicle screws at the top and bottom ends of the instrumentation.If pelvic imbalance is present and the patient is nonambulatory, pelvic fixation with iliac screws is advised.First round correction of the deformity is achieved with a cantilever technique; correction fine-tuning can be performed by tightening sublaminar wires.Consider utilizing thicker rods in cases of idiopathic or cerebral palsy EOS.

Acronyms and Abbreviations

EOS = early-onset scoliosisAP = anteroposteriorEV = end vertebraSSEP = somatosensory evoked potentialsMEP = motor evoked potentialsPJK = proximal junctional kyphosisSMA = spinal muscular atrophyCP = cerebral palsyPACU = post-anesthesia care unit.

Early-onset scoliosis: a narrative review

Early-onset scoliosis (EOS) is defined as any spinal deformity that is present before 10 years old, regardless of etiology.

Deformity must be evaluated based on the intercorrelation between the lungs, spine, and thorax.

Curvatures of early-onset have increased risk of progression, cardiorespiratory problems, and increased morbidity and mortality.

Progression of the deformity may produce thoracic insufficiency syndrome, where a distorted thorax is unable to support normal respiratory function or lung growth.

Management and treatment of EOS should pursue a holistic approach in which the psychological impact and quality of life of the patient are also taken into consideration.

Growth-friendly surgical techniques have not met the initial expectations of correcting scoliotic deformity, promoting thoracic growth, and improving pulmonary function.

A comparison of the post-fusion outcome of patients with early-onset scoliosis treated with traditional and magnetically controlled growing rods

AIMS

The aim of this study was to compare the clinical and radiological outcomes of patients with early-onset scoliosis (EOS), who had undergone spinal fusion after distraction-based spinal growth modulation using either traditional growing rods (TGRs) or magnetically controlled growing rods (MCGRs).

METHODS

We undertook a retrospective review of skeletally mature patients who had undergone fusion for an EOS, which had been previously treated using either TGRs or MCGRs. Measured outcomes included sequential coronal T1 to S1 height and major curve (Cobb) angle on plain radiographs and any complications requiring unplanned surgery before final fusion.

RESULTS

We reviewed 43 patients (63% female) with a mean age of 6.4 years (SD 2.6) at the index procedure, and 12.2 years (SD 2.2) at final fusion. Their mean follow-up was 8.1 years (SD 3.4). A total of 16 patients were treated with MCGRs and 27 with TGRs. The mean number of distractions was 7.5 in the MCGR group and ten in the TGR group (p = 0.471). The mean interval between distractions was 3.4 months in the MCGR group and 8.6 months in the TGR group (p < 0.001). The mean Cobb angle had improved by 25.1° in the MCGR group and 23.2° in TGR group (p = 0.664) at final follow-up. The mean coronal T1 to S1 height had increased by 16% in the MCGR group and 32.9% in TGR group (p = 0.001), although the mean T1 to S1 height achieved at final follow-up was similar in both. Unplanned operations were needed in 43.8% of the MCGR group and 51.2% of TGR group (p = 0.422).

CONCLUSION

In this retrospective, single-centre review, there were no significant differences in major curve correction or gain in spinal height at fusion. Although the number of planned procedures were fewer in patients with MCGRs, the rates of implant-related complications needing unplanned revision surgery were similar in the two groups. Cite this article: Bone Joint J 2022;104-B(2):257-264.

Treatment of infantile idiopathic scoliosis using a novel thoracolumbosacral orthosis: a case report

Background

The recommended treatment for mild to moderate infantile idiopathic scoliosis curves involves serial casting. There are concerns, however, regarding the safety of repeated casting in very young children owing to the requirement for anesthetization during the casting process. Very little research has been conducted on the influence of bracing as an initial treatment for scoliosis in this age group. This report details the successful treatment of a large thoracic curve using a thoracolumbosacral orthosis in an infant diagnosed with infantile idiopathic scoliosis.

Case presentation

The Dutch-Australian patient presented at 11 weeks of age with a 44° thoracic scoliosis and a rib vertebral angle difference of 14°. The history and physical examination failed to reveal a cause of the curvature, and a diagnosis of infantile idiopathic scoliosis was made. The patient was prescribed a thoracolumbosacral orthosis (ScoliBrace) to be worn on a part-time basis for a period of 8 months. At the end of the bracing program, the patient’s curve had been reduced to 7° and a rib–vertebral angle difference of 0°. A final follow-up of the patient at 2 years after the cessation of treatment revealed no evidence of scoliosis. The parents were compliant with the bracing protocol and reported that the treatment was tolerated by the infant.

Conclusion

The use of an orthosis as a standalone treatment in this patient resulted in significant reduction in a large thoracic scoliosis. Based on the results witnessed in this patient, further investigation into bracing as an alternative to casting is warranted.

How much does depth matter? Magnetically controlled growing rod distraction directly influenced by rod tissue depth

PURPOSE

Magnetically controlled growing rod (MCGR) for the treatment of early-onset scoliosis (EOS) is a relatively innovative technique. MCGR benefits over traditional growing rods are known but limitations and complications are being revealed. The purpose of this study was to examine the importance of tissue depth on rod lengthening.

METHODS

A single-institution retrospective review of 72 MCGR patients was performed. Ultrasound measured rod distraction. Differences in programmed and actual distraction, and complications were recorded. Tissue depths and achieved length were averaged and used to construct a regression to account for variability.

RESULTS

Percentage of std and offset orientation rod lengthening relative to the programmed distraction was inversely proportional to rod depth (std R = 0.50, p = 0.002) (offset R = 0.60, p < 0.001). Expected std rod lengthening achieved decreased by 1.46%/mm depth. Expected offset rod lengthening achieved decreased by 1.68%/mm depth. 28 pts (38.9%) sustained complications. Age, sex, BMI, standard tissue depth, and/or offset tissue depth had no predictive ability with respect to complications sustained (overall model R = 0.31, p = 0.36).

CONCLUSION

In a series of EOS surgical patients treated with MCGRs, the relationship between percentage of programmed lengthening achieved as well as total lengthening was inversely proportional to tissue depth of the rod. There was a trend towards increasing frequency of complications recorded with decreasing tissue depth though this was not significant. These data can help with surgical planning during MCGR placement.

Developments, Focuses, and Trends in Early-Onset Scoliosis From 2005 to 2020: A Systematic Bibliometric Analysis

OBJECTIVE

Although several studies have been reported on early-onset scoliosis (EOS), a bibliometric analysis is still lacking. A systematic bibliometric analysis will enable researchers to understand the scope of the research topics, identify research focuses and key literature, and predict future research directions.

METHODS

Literature data were retrieved from the Web of Science Core Collection database. The Web of Science Results Analysis and Citation Report were used to analyze the reported studies in different views. CiteSpace and VOSviewer were used for further analysis, including a cooperation network analysis of the authors, institutions, countries and/or regions, discipline and journal analysis, reference co-citation analysis, and keyword co-occurrence analysis.

RESULTS

The final analysis included 674 relevant studies reported from 2005 to 2020. During the study period, the field of EOS has expanded rapidly. Multiple cooperation was found among the authors, institutions, and countries and/or regions, with some making great contributions. The results of the reference co-citation analysis showed that the studies had several main focuses, including the growing rod (GR), magnetically controlled GR, an EOS 24-item questionnaire, and a growth evaluation.

CONCLUSIONS

From 2005 to 2020, surgical treatment has remained the focus of research in the EOS field. The magnetically controlled GR is the latest research focus, which might become more comprehensive in the future. The Gr has remained the most popular topic, and potential new surgical techniques might require improvement to become the favored techniques. In addition, assessing the health-related quality of life and growth parameters of patients with EOS have become a popular topic.

Validation of the Brazilian Portuguese Version of the 24-Item Early-Onset Scoliosis Questionnaire

STUDY DESIGN

Multicenter prospective study.

OBJECTIVES

To validate the Early-Onset Scoliosis 24 Questionnaire (EOSQ-24) questionnaire for the Brazilian Portuguese language, a widely used tool for assessing the impact of different treatments and interventions in EOS patients.

METHODS

The EOSQ-24 questionnaire was cross-culturally adapted following guidelines already published. After language adjustments by a group of experts, the final version of the Brazilian Portuguese EOSQ-24 was applied to a group of 76 patients (35 male and 41 female). Internal consistency was evaluated using the Cronbach α coefficient and item-total correlations. Continuous variables were recorded as median values and interquartile ranges and categorical variables as percentages.

RESULTS

In the study group, 76 patients were evaluated. The total EOSQ-24 Cronbach α coefficient was 0.883, indicating excellent reliability. The internal consistency of EOSQ-24 was assessed in 3 domains: patient quality of Life, parental burden, and satisfaction (Cronbach α: 0.816-0.934). The range across all subdomains was 0.473 to 0.934. Floor effects for the 24 items were between 1.3% and 43.4% and ceiling effects, between 3.9% and 42.1%.

CONCLUSIONS

The Brazilian Portuguese adaptation of the EOSQ-24 shows excellent reliability and can be a valid tool for psychometric assessment of children with EOS.

The Effect of Proximal Anchor Choice During Distraction-based Surgeries for Patients With Nonidiopathic Early-onset Scoliosis: A Retrospective Multicenter Study

BACKGROUND

It is unclear whether the type of proximal anchor affects the spine length achieved with distraction-based surgeries in patients with nonidiopathic early-onset scoliosis (EOS). Since distraction may produce kyphosis, spine length should be assessed in the sagittal plane using the sagittal spine length (SSL-curved arc length of the spine in the sagittal plane). Our purpose was to determine if the type of proximal anchor in distraction-based surgeries will affect final spine length.

METHODS

Patients with nonidiopathic EOS treated with distraction-based systems (minimum 5 y follow-up, 5 lengthenings) were identified from 2 EOS registries. Radiographic analysis preoperative, postimplant (L1), and after each lengthening (L2-L5, L6-L10, L11-L15) was performed with the primary outcome of T1-S1 SSL.

RESULTS

We identified 126 patients-70 had rib-based implants (52 congenital, 9 syndromic, 9 neuromuscular) and 56 had spine-based implants (15 congenital, 29 syndromic, 12 neuromuscular) with preoperative age 4.6 years, scoliosis 75 degrees, and kyphosis 48 degrees. After initial correction (P<0.05), scoliosis remained constant [58 degrees (13 to 104 degrees) at L11-L15] and kyphosis increased over time [38 degrees (9 to 108 degrees) at L1 to 60 degrees (17 to 134 degrees) at L11-L15] (P<0.05). Preoperative SSL was higher in the spine-based group (29.6 cm) when compared with the rib-based group (25.2 cm) (P<0.05). This difference was maintained after initial implantation (spine-based: 32.2 cm vs. rib-based: 26.7 cm, P<0.05) and at final follow-up (spine-based: 37.0 cm vs. rib-based: 34.4 cm, P<0.05). As preoperative SSL differed between groups, maximum SSL gains per interval were also normalized to preoperative SSL. There was no statistically significant difference between groups at L1, L2-L5, and L6-L10. However, at L11-L15, the rib-based group achieved a more relative increase in spine length compared with the spine-based group (45% vs. 31%, P<0.05).

CONCLUSION

At minimum 5 year follow-up, distraction-based surgeries increased spine length for patients with nonidiopathic EOS; regardless of proximal anchor type.

Low Preoperative Lung Functions in Children With Early Onset Scoliosis Predict Postoperative Length of Stay

INTRODUCTION

Children with early onset scoliosis (EOS) undergoing spine surgery often have significant respiratory disease. Preoperative risk assessments that predict an increased length of hospital stay (LOS) for this group have not been previously evaluated.

METHODS

A voluntary protocol using preoperative lung function studies began among participants of a multicenter registry in 2016. Preoperative assessments were standardized to include spirometry, blood hemoglobin levels, serum bicarbonate, albumin and prealbumin; radiographic parameters of the spine, C-EOS classification and need for preoperative pulmonary assistance before initial growth friendly device insertion or "definitive" spine fusion. Primary outcome was LOS postoperatively. Data, including age, diagnosis, and type of surgery, was collected prospectively. Secondary outcomes measured included intensive care unit LOS, requirement for new pulmonary assistance on discharge, and pulmonary complications. Groups were compared using the Fisher exact tests.

RESULTS

Of 525 children enrolled, 101 (20%) had preoperative spirometry. Median age was 8.9 years [interquartile range (IQR): 4.27]. Etiologies for EOS included 29 neuromuscular (28%), 33 idiopathic (32%), 19 syndromic (19%), and 22 congenital (21%) scoliosis. Eighty (78%) had growing rod (GR) insertions; 23 (22%) had spine fusion SF. Eighteen subjects (17%) were hospitalized ≥7 days (median=9 d); 83 had a LOS <7 days (median=3 d). Percentage of forced vital capacity (FVC%) predicted was inversely associated with LOS ≥7 days with a median of 75.3% (IQR: 41.7) for LOS <7 days and 51.7% (IQR: 41.6) (P=0.02). There were no detectable differences in LOS for other preoperative values.

CONCLUSION

FVC predicted ≤50% preoperatively in children undergoing initial growth friendly rod insertion or definitive fusion after growth friendly treatment is associated with an increased risk of postoperative hospital stays ≥7 days. As demonstrated in previous studies, severe restrictive lung disease (FVC% predicted at or below 50%) is associated with increased risk of poorer outcomes for EOS patients.

Early Complications in Vertical Expandable Prosthetic Titanium Rib and Magnetically Controlled Growing Rods to Manage Early Onset Scoliosis

OBJECTIVES

The aim of this study is to examine whether surgical treatment of early onset scoliosis (EOS) with magnetically controlled growing rods (MCGRs) or a vertical expandable prosthetic titanium rib (VEPTR) resulted in fewer short-term (24 months) complications and reoperations.

BACKGROUND

EOS is a challenging problem for spine surgeons that has been managed with different growth-friendly instrumentation systems. Although rib-based devices encourage spinal growth via regular lengthening, the high rate of complications and reoperations leads us to use spine-based devices such as MCGRs to mitigate this concern.

METHODS

A total of 35 EOS patients were included in the study. Twenty patients were included in the VEPTR group, and 15 patients were included in the MCGR group. Demographic data and 2 years of postoperative complications and reoperations were reviewed retrospectively. As secondary outcomes, radiographic outcomes were reported preoperatively and 1 year after surgery. Indications for this technique and complications were collected from the charts.

RESULTS

Demographic data showed no significant differences between the 2 groups. Significant differences were found in the complications rate at 2 years, with 65% complications in the VEPTR group and 13.3% complications in the MCGR group (P < .001). The reoperation rate at 2 years was also significantly higher in the VEPTR group, with 50% versus 13.3% in the MCGR group (P = .0009). As secondary outcomes, radiological parameters such as main curve Cobb angle correction (P = .001) and apical vertebral translation (P = .002) were significantly higher in the MCGR group. Significant differences were also found in sagittal profile parameters; T1-T12 and T1-S1 were significantly higher in the MCGR group (P < .001).

CONCLUSIONS

According to our results, VEPTR has significantly higher complication and reoperation rates at 2 years postsurgery compared with MCGR.

LEVEL OF EVIDENCE

4.

Can distraction-based surgeries achieve minimum 18 cm thoracic height for patients with early onset scoliosis?

PURPOSE

Karol et al. introduced the concept that 18 cm thoracic height is the critical point where a patient with early onset scoliosis (EOS) can maintain adequate pulmonary function. Our purpose was to determine if distraction-based surgeries will increase thoracic spine height to at least 18 cm in patients with EOS.

METHODS

Patients with EOS treated with distraction-based systems (minimum 5 years follow up, minimum five lengthenings). Radiographic analysis of thoracic spine height (T1-T12) at the last lengthening procedure.

RESULTS

One hundred and fifty-three patients (67 congenital, 21 neuromuscular, 38 syndromic, 27 idiopathic) with pre-operative mean age 4.6 years, scoliosis 75°, kyphosis 47° were evaluated. Their mean age at final lengthening procedure was 11 years (6-16), average number of lengthening procedures was 10.5 (4-21), mean final scoliosis was 53°, and mean final kyphosis was 58°. Final thoracic height was > 18 cm in 65% and was > 22 cm in 31% of patients. Based on etiology, only 48% of the congenital patients reached 18 cm compared to 81% neuromuscular, 84% syndromic and 67% idiopathic. This height gain was closely related to the percentage of scoliosis correction achieved for each etiology. Comparing congenital etiology to other etiologies, there was a lower percentage of patients in the congenital group that passed the 18 cm threshold (48% vs. 78%) (p < 0.05).

CONCLUSION

At minimum 5 years follow up, distraction-based surgeries increased thoracic height for patients with EOS to greater than 18 cm in 65% of patients; however, only 48% of congenital patients reached this thoracic height threshold.

DESIGN

Retrospective review of prospectively collected registry data. LOI III.

Complications of dual growing rod with all-pedicle screw instrumentation in the treatment of early-onset scoliosis

BACKGROUND

Treatment of early-onset scoliosis (EOS) is still a challenge to patients, families, and surgeons. Previous studies have indicated that EOS patients are at high risk for complications following growth-friendly surgery. This study was performed to evaluate the results and complications of all-pedicle screw dual growing rod instrumentation in the treatment of EOS.

METHODS

In an IRB-approved retrospective study, we searched the electronic medical records of our institution for all patients who underwent posterior spinal instrumentation for scoliosis between March 2014 and March 2017. Patients under the age of 10 at the time of surgery who were treated with a growth-friendly technique were then selected. Patients with incomplete records and less than 2 years of follow-up were excluded. Charts, operative notes, clinic visits, and radiographs were extracted. Radiographs were reviewed, and the main curve Cobb angle, thoracic kyphosis, pelvic tilt, pelvic incidence, sacral slope, and proximal junctional angles were measured. We specifically looked for any intra-operative or post-operative complications. Statistical analysis was performed to determine the risk factors of complications.

RESULTS

A total of 42 patients with a mean age of 4.8 ± 2.1 years (range, 1.5-8 years) were included in the final analysis. Patients were followed for a median of 34 months (range, 24-55). The major curve was corrected from a mean of 42.9° ± 10.7° to 28.8° ± 9.6° at the latest follow-up. Proximal junctional angles and thoracic kyphosis increased significantly during the follow-up period (both P values < 0.001). A total of 7 complications (17%) were observed. Four patients (10%) developed superficial surgical site infections, all of which resolved with antibiotics and one round of surgical debridement. Three cases (7%) of proximal junctional kyphosis (PJK) were encountered during the study period, none of which required revision surgery. Pre-operative thoracic kyphosis was the only significant risk factor for the development of PJK.

CONCLUSIONS

Our findings suggest that in settings without access to magnetically controlled growing rods, dual growing rods with all-pedicle screw instrumentation is still a viable treatment strategy with comparable results and complications. The most common complications are infection and PJK, with the latter being associated with a larger pre-operative thoracic kyphosis.

Mid-term results of a modified self-growing rod technique for the treatment of early-onset scoliosis

AIMS

To report the mid-term results of a modified self-growing rod (SGR) technique for the treatment of idiopathic and neuromuscular early-onset scoliosis (EOS).

METHODS

We carried out a retrospective analysis of 16 consecutive patients with EOS treated with an SGR construct at a single hospital between September 2008 and December 2014. General demographics and deformity variables (i.e. major Cobb angle, T1 to T12 length, T1 to S1 length, pelvic obliquity, shoulder obliquity, and C7 plumb line) were recorded preoperatively, and postoperatively at yearly follow-up. Complications and revision procedures were also recorded. Only patients with a minimum follow-up of five years after surgery were included.

RESULTS

A total of 16 patients were included. Six patients had an idiopathic EOS while ten patients had a neuromuscular or syndromic EOS (seven spinal muscular atrophy (SMA) and three with cerebral palsy or a syndrome). Their mean ages at surgery were 7.1 years (SD 2.2) and 13.3 years (SD 2.6) respectively at final follow-up. The mean preoperative Cobb angle of the major curve was 66.1° (SD 8.5°) and had improved to 25.5° (SD 9.9°) at final follow-up. The T1 to S1 length increased from 289.7 mm (SD 24.9) before surgery to 330.6 mm (SD 30.4) immediately after surgery. The mean T1 to S1 and T1 to T12 growth after surgery were 64.1 mm (SD 19.9) and 47.4 mm (SD 18.8), respectively, thus accounting for a mean T1 to S1 and T1 to T12 spinal growth after surgery of 10.5 mm/year (SD 3.7) and 7.8 mm/year (SD 3.3), respectively. A total of six patients (five idiopathic EOS, one cerebral palsy EOS) had broken rods during their growth spurt but were uneventfully revised with a fusion procedure. No other complications were noted.

CONCLUSION

Our data show that SGR is a safe and effective technique for the treatment of EOS in nonambulatory hypotonic patients with a neuromuscular condition. Significant spinal growth can be expected after surgery and is comparable to other published techniques for EOS. While satisfactory correction of the deformity can be achieved and maintained with this technique, a high rate of rod breakage was seen in patients with an idiopathic or cerebral palsy EOS. Cite this article: Bone Joint J 2020;102-B(11):1560-1566.

Characterizing Use of Growth-friendly Implants for Early-onset Scoliosis: A 10-Year Update

BACKGROUND

Growth-friendly treatment of early-onset scoliosis (EOS) has changed with the development and evolution of multiple devices. This study was designed to characterize changes in the use of growth-friendly implants for EOS from 2007 to 2017.

METHODS

We queried the Pediatric Spine Study Group database for patients who underwent index surgery with growth-friendly implants from July 2007 to June 2017. In 1298 patients, we assessed causes of EOS; preoperative curve magnitude; age at first surgery; patient sex; construct type; lengthening interval; incidence of "final" fusion for definitive treatment; and age at definitive treatment. α=0.05.

RESULTS

From 2007 to 2017, the annual proportion of patients with idiopathic EOS increased from 12% to 33% (R=0.58, P=0.006). Neuromuscular EOS was the most common type at all time points (range, 33% to 44%). By year, mean preoperative curve magnitude ranged from 67 to 77 degrees, with no significant temporal changes. Mean (±SD) age at first surgery increased from 6.1±2.9 years in 2007 to 7.8±2.5 years in 2017 (R=0.78, P<0.001). As a proportion of new implants, magnetically controlled growing rods increased from <5% during the first 2 years to 83% in the last 2 years of the study. Vertically expandable prosthetic titanium ribs decreased from a peak of 48% to 6%; growth-guidance devices decreased from 10% to 3%. No change was seen in mean surgical lengthening intervals (range, 6 to 9 mo) for the 614 patients with recorded lengthenings. Final fusion was performed in 88% of patients who had undergone definitive treatment, occurring at a mean age of 13.4±2.4 years.

CONCLUSIONS

From 2007 to 2017, neuromuscular EOS was the most common diagnosis for patients treated with growth-friendly implants. Patient age at first surgery and the use of magnetically controlled growing rods increased during this time. Preoperative curve magnitude, traditional growing rod lengthening intervals, and rates of final fusion did not change.

LEVEL OF EVIDENCE

Level II.

Evolution of casting techniques in early-onset and congenital scoliosis

Casting is being utilized as a therapeutic strategy in some mild to moderate cases obviating surgical intervention for management of early-onset scoliosis (EOS). Bracing, another conservative modality, applies comparable correcting forces on chest wall and axial skeleton. But cast application carries additional advantage of sustained restorative force which bypasses issue of compliance seen with brace wear. There is no specific blanket treatment, conservative or surgical, for the early-onset spinal deformities. Serial cast application provides near total correction of less severe curves (less than 500 to 600) if treatment is initiated before age of 2 yrs. In this review article, we will assess the evolution of plaster cast application in management of EOS and also describe technique of EDF (Elongation- Derotation- Flexion) casting.

Unplanned return to operation room (OR) following growing spinal constructs (GSCs) in early onset scoliosis (EOS)-a multi-centric study

PURPOSE

To evaluate the incidence and risk factors associated with the unplanned return to OR in EOS.

METHODS

Medical records of 51 patients of EOS operated at three different centres using various types of GSCs were evaluated for complications requiring unplanned surgeries. Data were analysed to find out rate of unplanned surgeries in relation to the aetiology, age and Cobb angle at index surgery, type of implant, cause of unplanned surgery, and management required.

RESULTS

Out of 51 patients, three did not meet inclusion criteria. Forty-eight patients of EOS operated by GSCs with a mean age of 6.7 years (range 2-12 years) with an average follow-up of 67.3 months were studied. There were 30 congenital, 10 idiopathic, 4 syndromic, and 4 neuromuscular cases. Thirty-nine out of 48 patients had one or more unplanned surgeries on follow-up (81.25%). Out of total 248 surgeries following index procedure, 82 were unplanned surgeries (33.06%), including 53 implant revisions, 12 implant-removal, 14 debridement, and 2 flaps. The common complications were 24.14% rod/screw breakage, 42.53% anchor pull-out, 16.09% infections, 6.90% wound dehiscence, and 4.6% neuro deficits. Unplanned surgeries were significantly higher in syndromic (58.8%) and neuromuscular (52.9%) than congenital (27.2%) and idiopathic (37.8%) cases (p < 0.05). Age at index procedure < 5 years had higher unplanned surgeries than age > 5 years (2.5 and 1.23 per patient, respectively,  p < 0.05). Type of implant and initial Cobb angle did not significantly affect the rate of unplanned surgeries (p  > 0.05) CONCLUSION: GSCs in EOS require a frequent revisit to operation room which should be well understood by the surgeon and parents.

Distraction-based surgeries increase thoracic sagittal spine length after ten lengthening surgeries for patients with idiopathic early-onset scoliosis

STUDY DESIGN

Retrospective, comparative, multicenter.

OBJECTIVES

To determine if the choice of proximal anchor affects thoracic sagittal spine length (SSL) for children with idiopathic early-onset scoliosis (EOS). Debate exists as to whether spine growth is maintained during treatment for EOS. As rib- (RB) and spine-based (SB) distraction procedures may be kyphogenic, the traditional measurement of spine growth on coronal radiographs may not identify out-of-plane increase in spine length. A measure of SSL, along the spine's sagittal arc of curvature, has been validated to reliably assess the length of the thoracic spine.

METHODS

Patients with idiopathic EOS treated with distraction-based systems (minimum 5-year follow-up, five lengthening surgeries) with radiographic analysis preoperatively, postimplant (L1), and during lengthening periods (L2-L5, L6-L10) were evaluated with primary outcome of T1-T12 SSL.

RESULTS

We identified 34 patients (14 RB, 20 SB) with preoperative age 4.9 years (4.2 RB vs. 5.4 SB), scoliosis 72° (60° RB vs. 77° SB; p < 0.05), kyphosis 39° (50° RB vs. 34° SB; p < 0.05), and SSL 17.8 cm (15.5 RB vs. 18.5 SB; p < 0.05). After initial scoliosis correction from implantation, scoliosis remained constant over time. RB patients had greater kyphosis than SB patients: L1, 46° RB vs. 19° SB (p < 0.05); L2-L5, 50° RB vs. 27° SB (p < 0.05); L6-L10, 56° RB vs. 26° SB (p < 0.05). SSL increased for both groups from preoperative to the tenth lengthening (p < 0.05). As compared with RB patients, SB patients had higher SSL preoperatively and maintained this difference to the tenth lengthening (p < 0.05). After ten lengthening surgeries, when normalized to preoperative SSL, relative thoracic growth was greater for RB (27%) than for SB patients (19%) (p < 0.05).

CONCLUSION

Regardless of proximal anchor choice, thoracic length continued to increase during the distraction phase of treatment for idiopathic EOS.

LEVEL OF EVIDENCE

Level III.

Staged instrumentation with magnetically controlled growing rods in early-onset scoliosis: indications and preliminary outcomes

BACKGROUND

Severe scoliosis, kyphosis, stiffer curves, short trunk height, and poor bone density are known risk factors for instrumentation failure with traditional growing rods or magnetically controlled growing rods (MCGR). To minimize the risk of instrumentation failure in managing complex early-onset scoliosis (EOS) with MCGR, we propose a strategy for staged MCGR insertion.

METHODS

We performed a single-center retrospective review of all consecutive MCGR cases with 24 months' minimum follow-up. Inclusion criteria included diagnosis of EOS of any etiology with severe and stiff curves in the coronal or sagittal planes, poor bone density, short trunk height (T1-T12 smaller than 150 mm) or previous instrumentation failure managed with staged MCGR. During the first stage, anchor points and halo-gravity were applied, followed by halo-gravity traction. At a second stage, halo-gravity was removed and MCGR were inserted. Outcome measures included pre- and postoperative radiographic measurements and complications.

RESULTS

Seventeen patients with a median age of 7 (range 6-9) years were managed in two stages. Indications for two-stage surgery were short trunk height (T1-T12 height less than 150 mm) in six patients, five poor bone quality, three dislodgement of proximal anchor points in previous instrumentation, and three rigid curves. The rate of unplanned revision surgeries was 11.8%. No infections or traction-related complications were found.

CONCLUSIONS

According to our results, the staged MCGR insertion strategy combined with halo-gravity traction to manage complex EOS yielded a relatively low instrumentation failure rate as compared with the rates previously reported in the current literature. To our knowledge, this is the first study reporting the staged strategy for instrumentation with MCGR.

LEVEL OF EVIDENCE

IV.

Posterior vertebral column resection for rigid proximal thoracic kyphoscoliosis with broken growing rods in a patient with Desbuquois dysplasia

STUDY DESIGN

Case report.

OBJECTIVE

To describe the importance of preoperative halo-gravity traction and posterior vertebral column resection (PVCR) for severe proximal thoracic kyphoscoliosis associated with Desbuquois dysplasia, after breakage of a growing rod construct. Desbuquois dysplasia is a rare, autosomal recessive chondrodysplasia characterized by short stature, joint laxity, kyphoscoliosis, and characteristic facial dysmorphism. Our 8-year-old patient developed severe, progressive, infantile-onset kyphoscoliosis and had been initially treated with Vertical Expandable Prosthetic Titanium Rib (VEPTR) rods. She subsequently underwent growing rod placement, but the eventual rod fracture resulted in a severe angular kyphosis.

METHODS

Clinical and radiographic case review.

RESULTS

The broken implants were removed, and she was treated with 2.5 months of preoperative halo-gravity traction. She then underwent a T4 PVCR and C7-L4 instrumented posterior spinal fusion. The patient had an uneventful postoperative course without any neurologic problems. Two years postoperatively, correction was well maintained with appropriate alignment and balance without implant breakage.

CONCLUSION

To our knowledge, this is the first report of treatment of spinal deformity associated with Desbuquois dysplasia. Our results suggest that preoperative halo-gravity traction and PVCR are safe and efficacious techniques for severe rigid kyphoscoliosis in the cervicothoracic region associated with broken growing rods in a patient with Desbuquois dysplasia.

LEVEL OF EVIDENCE

Level IV.

Spinal Lengthening With Magnetically Controlled Growing Rods: Data From the Largest Series of Explanted Devices

STUDY DESIGN

Laboratory analysis of explanted MAGnetic Expansion Control (MAGEC) rods.

OBJECTIVE

The aim of this study was to identify the in vivo lengthening of MAGEC rods.

SUMMARY OF BACKGROUND DATA

Little data is available regarding the lengthening achieved by MAGEC rods.

METHODS

Cases were identified from the largest series of independently analyzed explanted MAGEC rods. The in vivo growth of rods was determined by the distance between the first "growth mark" and the actuator. The instrumented spinal lengthening was calculated for each construct. Constructs were considered functional if all rods could lengthen with external remote controller activation and no rods were "telescoping".

RESULTS

Fifty-five MAGEC constructs (99 rods) from 53 patients treated at 10 centers were included. The mean age at insertion was 8.5 years with rods implanted a mean of 35 months. Sixty rods were suitable for analysis with mean lengthening 21.7 mm, 8.9 mm/year. Of these 60 rods, three were maximally distracted. Mean instrumented spinal lengthening for 38 suitable cases was 22.1 mm, 8.4 mm/year. This was positively correlated with the duration of implantation (r = 0.34, P = 0.04) but negatively with patient age at insertion (r = -0.35, P = 0.03). The rate of instrumented spinal lengthening was negatively correlated with duration of implantation (r = -0.47, P = 0.004). Of 55 constructs, 34 were nonfunctional at time of removal with nine functional and 12 indeterminate. Functional constructs had been implanted significantly less time (20.0 vs. 39.7 months, P < 0.001) and lengthened less than those nonfunctional (12.3 mm vs. 23.3 mm, P = 0.04).

CONCLUSION

This multicenter explant study represents the largest cohort managed with MAGEC rods reported. Rods are very rarely removed having fully lengthened with mean instrumented spinal growth of 22 mm over the implant's life. This may be explained by a high rate of lengthening mechanism failure in received rods after around 3 years in vivo. Our findings question the effectiveness of the MAGEC system and mandate urgent comparative clinical studies.

LEVEL OF EVIDENCE

4.

The Association Between the Classification of Early-onset Scoliosis and Smith Complications After Initiation of Growth-friendly Spine Surgery: A Preliminary Study

BACKGROUND

Early-onset scoliosis (EOS) is a complex, heterogeneous condition involving multiple etiologies, genetic associations, and treatment plans. In 2014, Williams and colleagues proposed a classification system of EOS (C-EOS) that categorizes patients by etiology, Cobb angle, and kyphosis. Shortly after, Smith and colleagues validated a classification system to report complications of growth-friendly spine instrumentation. Severity refers to the level of care and urgency required to treat the complication, and can be classified as device-related or disease-related complications. The purpose of this study was to investigate if C-EOS can be used as a reliable predictor of Smith complications to better risk stratify these young, surgical patients.

METHODS

This study queried retrospective data from a large multicenter registry with regard to growth-friendly spine instrumentation in the EOS population. One-hundred sixteen patients were included in final data analysis to investigate the outcomes of their growth-friendly procedures according to the Smith complication classification system.

RESULTS

There were 245 Smith complications distributed among 116 patients included in this study (2.1 complications per patient). The majority of the complications were device related requiring at least one unplanned trip to the operating room (Smith Device Complication IIA or IIB; 111 complications). There were no complications that caused abandonment of growth-friendly instrumentation (Smith Complication III) and no mortalities (Smith Complication IV). The most severely affected EOS group was the hyperkyphotic syndromic group with a major curve angle >50 degrees (S3+), with 3.4 complications per patient. The least affect EOS group was the hyperkyphotic congenital group with a major curve angle between 20 and 50 degrees, with 0.3 complications per patient.

CONCLUSIONS

The C-EOS simplifies a complex pathology and the Smith complication classification scheme creates a language to discuss treatment of known complications of growth-friendly spine surgery. Although there is an association between more advanced C-EOS and Smith complications, there does not appear to be a correlation that can satisfy a risk stratification at this time.

LEVEL OF EVIDENCE

Level II.

Treatment of Idiopathic Scoliosis With Vertebral Body Stapling

STUDY DESIGN

Retrospective cohort.

OBJECTIVES

Identify the effectiveness of vertebral body stapling (VBS) in children with idiopathic scoliosis.

SUMMARY OF BACKGROUND DATA

VBS has been proposed as an alternative to bracing moderate curves in patients with adolescent idiopathic scoliosis (AIS) although a clear picture of comparative efficacy and safety remains to be established.

METHODS

Ten skeletally immature patients with AIS and curves between 25° and 35° underwent anterior VBS by a single surgeon from 2008 to 2018. Indications included strong family history, high ScoliScore, curve progression despite bracing, or as an alternative for patients/families refusing bracing. Patients with thoracic kyphosis greater than 40°, curvature with a level above T4 or below L4, and double major curves were contraindicated. Patients with hybrid surgical plans or those who failed to reach skeletal maturity were excluded. Age, gender, levels stapled, pre- and postoperative radiographs, and incidence of secondary surgical intervention were evaluated. Outcomes were also compared with untreated and braced subjects from the BrAIST study.

RESULTS

Ten patients met the inclusion criteria. Average age at VBS was 11.8 (9.7-13.5) with an average major Cobb angle of 30.9° (26°-35°). Average duration of follow-up was 6.4 years. All patients demonstrated curve correction at their first postoperative visit. At final follow-up, 50% of patients experienced curve progression greater than 5°, whereas the remaining 50% either remained stable or corrected over time. The five patients whose curves progressed underwent VBS at a significantly younger age (10.8 vs. 12.8; p value .003). Four of these patients required additional surgical intervention for worsening scoliosis.

CONCLUSIONS

Although early outcomes after VBS appear to parallel the results of bracing, stapling does not affect the percentage of patients ultimately requiring PSIF. Initial curve correction degraded over time in younger patients with significant growth remaining, and high rates of progression in this group, even with bracing, merits investigation into more efficacious treatment strategies.

LEVEL OF EVIDENCE

Level III.

Mechanical Performance of Posterior Spinal Instrumentation and Growing Rod Implants: Experimental and Computational Study

STUDY DESIGN

Experimental and computational study of posterior spinal instrumentation and growing rod constructs per ASTM F1717-15 vertebrectomy methodology for static compressive bending.

OBJECTIVE

Assess mechanical performance of standard fusion instrumentation and growing rod constructs.

SUMMARY OF BACKGROUND DATA

Growing rod instrumentation utilizes fewer anchors and spans longer distances, increasing shared implant loads relative to fusion. There is a need to evaluate growing rod's mechanical performance. ASTM F1717-15 standard assesses performance of spinal instrumentation; however, effects of growing rods with side-by-side connectors have not been evaluated.

METHODS

Standard and growing rod constructs were tested per ASTM F1717-15 methodology; setup was modified for growing rod constructs to allow for connector offset. Three experimental groups (standard with active length 76 mm, and growing rods with active lengths 76 and 376 mm; n = 5/group) were tested; stiffness, yield load, and load at maximum displacement were calculated. Computational models were developed and used to locate stress concentrations.

RESULTS

For both constructs at 76 mm active length, growing rod stiffness (49 ± 0.8 N/mm) was significantly greater than standard (43 ± 0.4 N/mm); both were greater than growing rods at 376 mm (10 ± 0.3 N/mm). No significant difference in yield load was observed between growing rods (522 ± 12 N) and standard (457 ± 19 N) constructs of 76 mm. Growing rod constructs significantly decreased from 76 mm (522 ± 12 N) to 376 mm active length (200 ± 2 N). Maximum load of growing rods at 76 mm (1084 ± 11 N) was significantly greater than standard at 76 mm (1007 ± 7 N) and growing rods at 376 mm active length (392 ± 5 N). Simulations with active length of 76 mm were within 10% of experimental mechanical characteristics; stress concentrations were at the apex and cranial to connector-rod interaction for standard and growing rod models, respectively.

CONCLUSION

Growing rod constructs are stronger and stiffer than spinal instrumentation constructs; with an increased length accompanied a decrease in strength. Growing rod construct stress concentration locations observed during computational simulation are consistent with clinically observed failure locations.

LEVEL OF EVIDENCE

5.

Distraction-Based Surgeries Increase Spine Length for Patients With Nonidiopathic Early-Onset Scoliosis-5-Year Follow-up

STUDY DESIGN

Retrospective, comparative.

OBJECTIVES

To determine if distraction-based surgeries will increase spine length in patients with nonidiopathic EOS and whether etiology affects final spine length.

SUMMARY OF BACKGROUND DATA

As early-onset scoliosis (EOS) has many etiologies, it is unclear whether etiology affects the spine length achieved with distraction-based surgeries. Since distraction may produce kyphosis, sagittal spine length (SSL; curved arc length of the spine in the sagittal plane) should be utilized.

METHODS

Patients with nonidiopathic EOS treated with distraction-based systems (minimum 5-year follow-up, 5 lengthenings) were identified from two EOS registries. Radiographic analysis preoperation, postimplant (L1), and after each lengthening (L2-L5, L6-L10, L11-L15) was performed with primary outcome of T1-S1 SSL.

RESULTS

We identified 126 patients (67 congenital, 38 syndromic, 21 neuromuscular) with a mean preoperative age of 4.6 years, scoliosis 75°, kyphosis 48°, and a mean of 12 lengthenings. After initial correction (p < .05), scoliosis remained constant (58° at L11-L15) and kyphosis increased (38° at L1 to 60° at L11-L15) (p < .05). SSL increased for the entire group from 27.1 cm preoperation to 35.3 cm at L11-L15 (p < .05) and during the distraction phase (29.2 cm at L1 to 35.3 cm at L11-L15) (p < .05). Preoperative SSL was higher in neuromuscular compared with congenital patients and maintained that difference until the 10th lengthening. Preoperative SSL did not differ between syndromic and congenital patients (28.0 cm vs. 25.6 cm); however, syndromic patients had greater SSL after implantation (L1: 30.5 cm vs. 26.8 cm) (p < .05) and maintained that difference until the 15th lengthening (37.1 cm vs. 34.3 cm) (p < .05).

CONCLUSION

At minimum 5-year follow-up, distraction-based surgeries increased spine length for all patients with nonidiopathic EOS; however, neuromusculars had higher preoperative spine length compared with congenital patients and maintained that difference until the 10th lengthening. Although congenital and syndromic patients had similar preoperative spine length, syndromic patients had greater SSL after implantation (L1) and maintained that difference until the 15th lengthening.

LEVEL OF EVIDENCE

Level III.

A comparison of growth among growth-friendly systems for scoliosis: a systematic review

BACKGROUND CONTEXT

The optimal method for surgical treatment of early onset scoliosis is currently unknown. Although the aim of growth-friendly systems is to reduce the curve and maintain growth, there is no consensus on how to measure spinal growth during and after the treatment. Different measurements of different segments (T1-S1, T1-T12, instrumented length) are used for different time points to evaluate growth. The aim of this review is to assess what measurements are used and to compare the growth-friendly systems based on spinal growth during treatment.

METHODS

The electronic MEDLINE, EMBASE, and Cochrane databases were systematically searched for original articles that reported growth for traditional growing rods (TGR), vertical expandable prosthetic titanium rib expansion technique (VEPTR), Shilla, magnetically controlled growing rods (MCGR), and Luque-trolley systems. All measurements were recorded, and weighted averages calculated in centimeter per year were compared.

RESULTS

We included 52 studies (26 TGR, 12 MCGR, 6 VEPTR, 4 Luque trolley, 1 Shilla, and 3 mixed). Often only one segment was reported (T1-S1 length in 22 studies, T1-T12 length in two studies, and instrumented length in five studies). The remaining 22 studies reported T1-S1 length in combination with T1-T12 length (15 studies) or instrumented length (eight studies). Spinalgrowth achieved by initial correction only was a considerable 3.9 cm (based on 34 studies) as well as the spinal growth achieved by the final fusion surgery (2.3 cm in four studies). To specifically assess growth achieved with the system, length gain after initial surgery and before final fusion in growth system graduates was considered. Only four TGR studies reported on this "true" spinal growth with 0.6 and 0.3 cm/y in the T1-S1 and T1-T12 segment, respectively.

CONCLUSIONS

Reporting on spinal growth is currently inadequate and does not allow a good comparison of different techniques. However, all systems often report growth similar to Dimeglio's T1-S1 spinal growth of 1 cm/y. It should be recognized though that a considerable portion of the reported spinal growth is the result of the initial and final surgical correction and not due to the growth-friendly implant.

Safe Parameters for Utilizing Magnetic Growth Rods in Patient With a Vagal Nerve Stimulator and Case Report

BACKGROUND

Magnetic growing rods are being utilized more frequently in children with early-onset scoliosis. Many of these children have multiple medical problems and additional medical devices implanted that utilize similar magnetic technology, including vagal nerve stimulator (VNS) devices. There is some concern that the external remote controller (ERC) used to control the magnetic growth rod will interact with these devices during lengthening procedures. We believe there are safe parameters which allow the magnetic growth rod ERC to be utilized in patients with an implanted VNS.

METHODS

A VNS device was tested in a simulation with the magnetic growth rods ERC to determine if it would activate/inactivate the device during a lengthening procedure. This study consists of 2 simulations. Simulation 1 evaluates placing the VNS adjacent to the ERC in the same coronal plane. Simulation 2 elevates the ERC placement above the device to simulate the thickness of a torso while increasing the distance of the VNS from the ERC in the coronal plane.

RESULTS

The time of exposure of the VNS device to the magnetic field had no correlation with activation. Distance had an effect on device activation. In the coronal plane of the device, activation occurred 43% of the time at 0 cm, 71% at 4 cm, and 5% activation at 8 cm. Greater than 10 cm had no activation. In the sagittal plane with the ERC 8 cm above the device, activation occurred 71% at 0 cm distance, 38% at 2 cm, and no activation occurred at a distance of >4 cm.

CONCLUSIONS

Utilization of the magnetic growth rod ERC can be carried out safely in patients with a VNS. Simulations show that an actuator implanted 4 cm from the VNS device in the coronal plane in a child with >8 cm chest wall thickness will not activate the VNS device. When choosing a rod configuration for implantation, the child's chest wall thickness and the ERC placement should be considered.

Decision Making of Graduation in Patients With Early-Onset Scoliosis at the End of Distraction-Based Programs: Risks and Benefits of Definitive Fusion

STUDY DESIGN

Retrospective comparative analysis.

OBJECTIVE

Study early-onset scoliosis (EOS) graduated patients to establish founded criteria for graduation decision making and determine the risks and benefits of definitive fusion.

SUMMARY OF BACKGROUND DATA

EOS is treated by growth-friendly techniques until skeletal maturity. Afterwards, patients can be "graduated," either by definitive fusion (posterior spinal fusion [PSF]) or by retaining the previous implants (Observation) with no additional surgery. Criteria for this decision making and the outcomes of definitive fusion are still underexplored.

METHODS

We analyzed a consecutive cohort of "graduated" patients after a distraction-based lengthening program. We gathered demographic, radiographic, and surgical data. The results of the two final treatment options were compared after 2 years' follow-up.

RESULTS

A total of 32 patients were included. Four patients had incomplete records. Thirteen underwent PSF, and 15 were observed. The mean age at initial treatment was 8 ± 3 years, with a mean follow-up of 8.3 ± 2.9 years. Both groups had similar preoperative and final radiographic parameters (p > .05). The criteria for undergoing PSF were as follows: implant-related complications, main curve magnitude (PSF = 63.2° ± 9° vs. OBS = 47.9° ± 15°; p = .008), curve progression >10°, and sagittal misalignment (SVA). During PSF 12/13 patients underwent multiple osteotomies, one vertebrectomy, and 3 costoplasties. Surgical time was 291.5 ± 58 minutes; blood loss was 946 ± 375 mL; and the number of levels fused was 13.7. Coronal deformity was corrected 31%, T1-S1 length gained was 31 ± 19.6 mm and T1-T12 length gained was 9.3 ± 39 mm; kyphosis was reduced by 22%. However, coronal balance worsened by 2.3 ± 30.8 mm. No major complications were encountered in these patients.

CONCLUSIONS

Graduation by PSF depended on unacceptable or progressive major curve deformity, sagittal misalignment, or complications with previous implants. Observation depended on curve stabilization, Cobb <50°, and coronal misalignment <20 mm. Definitive fusion effectively corrected coronal and sagittal deformity and increased trunk height. However, it exposed patients to a very demanding surgery without improvement in coronal balance.

LEVEL OF EVIDENCE

Level III, therapeutic.

Expert Consensus and Equipoise: Planning a Randomized Controlled Trial of Magnetically Controlled Growing Rods

STUDY DESIGN

Expert consensus building using combined Delphi method and Nominal group technique.

OBJECTIVES

To identify the current state of equipoise surrounding the use of magnetically controlled growing rods (MCGRs) and to determine consensus for planning a randomized controlled trial (RCT) with MCGRs.

BACKGROUND

The use of MCGRs for the treatment of early-onset scoliosis (EOS) is a new technology. Optimal use has not been thoroughly investigated and much uncertainty exists. Areas of uncertainty include construct architecture, timing of lengthenings, and amount of distraction per lengthening. Expert discussion and consensus is useful at this early juncture and necessary when designing an RCT.

METHODS

Two rounds of surveys were administered to a group of experienced pediatric spine surgeons, followed by a 2-hour, face-to-face meeting in November 2015 and a 1-hour, face-to-face meeting in February 2016. The first survey used example cases to establish agreement around the proper use of MCGRs and identified areas of equipoise and disagreement. The second survey again used example cases-this time selected for their equipoise status-to solicit trial arms for a potential RCT of MCGRs and identified important open questions in the use of MCGRs. Lastly, the face-to-face meetings employed iterative voting to preliminarily plan an RCT of MCGRs.

RESULTS

Following the Delphi survey rounds and the two Nominal face-to-face meetings, the group of experts decided on an MCGR RCT design that standardized all patients to bidirectional constructs, and randomized to a lengthening interval of 6 versus 16 weeks with a standardized equation for calculating the total yearly lengthening that approximates normal spine growth.

CONCLUSION

This endeavor indicates expert support for the use of MCGR in children older than 6 years, with curves greater than 60°. The uncertainty surrounding frequency of lengthening justifies an RCT of MCGRs.

LEVEL OF EVIDENCE

Level V.

Early-Onset Scoliosis: Updated Treatment Techniques and Results

STUDY DESIGN

This is a review of the current literature on early-onset scoliosis (EOS) techniques and treatment written by the Growing Spine Committee of the Scoliosis Research Society.

OBJECTIVES

The Growing Spine Committee of the Scoliosis Research Society sought to update the information available on the definition and treatment of EOS, including new information about existing techniques.

SUMMARY OF BACKGROUND DATA

EOS represents a diverse, heterogeneous, and clinically challenging group of spinal disorders occurring in children under the age of 10. Our understanding of EOS has changed dramatically in the last 15 years, and management of EOS has changed even more rapidly in the last five years.

METHODS

The Growing Spine Committee of the Scoliosis Research Society has embarked upon a review of the most current literature on EOS techniques and treatment.

RESULTS

This white paper provides recent updates on current techniques, including a summary of new modalities, indications, contraindications, and clinical results.

CONCLUSIONS

Although treatment of EOS is still challenging and complicated, the evolution of options and knowledge presents hope for better understanding and management in the future.

LEVEL OF EVIDENCE

Level V.

Stainless steel wear debris of a scoliotic growth guidance system has little local and systemic effect in an animal model

Options to treat early-onset scoliosis include guided-growth systems with sliding action between rods and pedicle screws. The wear was previously measured in an in vitro test, and in this in vivo rabbit model, we evaluated the local and systemic biological response to the stainless steel debris. Compared to the previous study, a relatively higher volume of representative wear particles with a median particle size of 0.84 μm were generated. Bolus dosages were injected into the epidural space at L4-L5 for a minimum of 36 rabbits across three treatment groups (negative control, 1.5 mg, and 4.0 mg) and two timepoints (12 and 24 weeks). Gross pathology evaluated distant organs and the injection site with a dorsal laminectomy to examine the epidural space and dosing site. Peri-implanted particle tissues were stained for immunohistochemical and quantitatively analyzed for IL-6 and TNF-α cytokines. Based on ISO 10993-6:2007 scoring, particles in the high-dose group were primarily non-irritant (12 weeks) with one slightly irritant. At 24 weeks, inflammatory cell infiltration was non-existent to minimal with all groups considered non-irritant at the injection site. Material characterization confirmed that particles detected in distant organs were stainless steel or contaminants. At 12 weeks, stainless steel groups demonstrated statistically increased amounts of cytokine levels compared to control but there was a statistical decrease for both at 24 weeks. These findings indicate that stainless steel wear debris, comparable to the expected usage from a simulated growth guidance system, had no discernible untoward biological effects locally and systemically in an animal model. © 2018 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 36:1980-1990, 2018.

Intraspinal Anomalies in Early Onset Scoliosis: Current Concepts

Early onset scoliosis (EOS) is deformity of the spine below the age of 5 years. Children with EOS are at risk of impaired thoracic cage development and pulmonary maturation. Initial evaluation consists of determining the etiological cause for EOS, i.e., congenital, neurogenic, idiopathic, or syndromic. The advent of magnetic resonance imaging in recent times has lead to increased awareness of neurogenic causes leading to EOS. Evaluation of spinal cord anomalies in EOS is very important as early diagnosis and treatment can help in deformity stabilization and regression. Also, any surgical or nonsurgical intervention to correct the deformity without prior treatment of spinal cord anomalies can lead to disastrous neurological complications.

Observed Length Increases of Magnetically Controlled Growing Rods are Lower Than Programmed

BACKGROUND

Magnetically controlled growing rods (MCGRs) are increasingly used in the treatment of early onset scoliosis (EOS). Few studies have reported whether desired lengthening can reliably be achieved, or if prior spine instrumentation and large tissue depths affect lengthening. In this clinical study of EOS patients, it was hypothesized that increases in rod length would equal programmed increases, patients with prior spine instrumentation would lengthen less than patients without prior surgery, and larger tissue depths would decrease lengthening success.

METHODS

A retrospective chart review was conducted on EOS patients with single and dual MCGRs placed between April 2014 to September 2015 and distracted at a single institution. Rod distraction was measured at each visit using ultrasound. Differences between programmed and actual distraction for each patient, and between groups with and without prior spine instrumentation, were determined by 2-tailed t tests. Regression and correlation were used to determine the relationship between tissue depth and length increases.

RESULTS

Thirty-one patients were included, 18 males, 13 females, age 8.1 (±2.5) years, with major curves measuring 60 (±14.6) degrees at time of MCGR insertion. In the 12 patients with prior instrumentation, time from initial growing rod placement to MCGR insertion was 23.1 (±10.6) months. The number of surgical procedures before MCGR insertion was 2.8 (±2.0). Total length increase relative to the programmed distraction was 86% (±21) (P<0.001). Length increases for patients with and without prior surgery were 87% (±23) and 86% (±19), respectively (P>0.9). Total lengthening was inversely proportional to tissue depth (r=0.38, P<0.01); the decrease in lengthening achieved was 2.1%/mm of tissue depth.

CONCLUSIONS

Increases in rod length were 14% lower than the programmed distraction. Prior instrumentation did not impact the amount of rod distraction. Greater distance between the rod and the skin surface negatively affected the magnitude of distraction.

The use of magnetically controlled growing rods in paediatric Osteogenesis Imperfecta with early onset, progressive scoliosis

Osteogenesis Imperfecta (OI) is a condition of bone fragility and can present with early onset scoliosis that can cause respiratory complications in later life. The fear of instrumenting the spine in OI is the possibility of fracture either on primary insertion or subsequent lengthening. Magnetically controlled growing rods were inserted to control a scoliosis in a 6-year old with OI type IV. Fixation was obtained using pedicle screws proximally and distally with sublaminar bands around the ribs proximally. These rods have been remotely lengthened on multiple occasions over a 2-year period. This has controlled the scoliosis whilst also allowing the spine to grow. There are no complications to report. This case reports the use of magnetically controlled growth rods used to manage early onset scoliosis in OI. Frequent lengthening, achieving small increases in length on every occasion protects against the risk of fracture during the lengthening procedure.

Staged Growing Rods With Preimplantation of Spinal Anchors for Complex Early Onset Scoliosis

BACKGROUND

Treatment of early onset scoliosis (EOS) with growing rods (GR) can be challenging in patients with significant deformity, hyperkyphosis, or poor bone quality, due to risks of neurological deficit and hardware pull-out. The objective of this study is to report a series of EOS patients managed with a 2-stage GR technique used to minimize these complications.

METHODS

Two-stage GR technique was performed in 8 patients at mean age of 5.4 (range, 3.4 to 7.9) years. At stage 1, proximal and distal anchors were implanted with local fusion. At stage 2, the distraction rods were inserted. There were at least 3 months between stages 1 and 2, and halo-gravity traction was used before stage 2 unless contraindicated. Demographic, clinical, and surgical data were retrospectively reviewed with mean 4.9 (range, 2.0 to 9.4) years of follow-up. Radiographic measurements including Cobb and kyphosis angles were evaluated before stage 1, after halo-gravity traction, after stage 2, and at last follow-up. Indications for staging, anchor healing time, and complications were collected and analyzed.

RESULTS

Indications for 2-stage surgery were poor bone quality in 5 patients and neurological changes during initial attempt at GR placement in 3 patients. The mean time between stage 1 and 2 was 23 (15 to 45) weeks. Patients have undergone mean 7 (3 to 16) lengthenings. Three patients have been converted to magnetically controlled GR. The major coronal Cobb angle improved from mean 81 degrees (range, 61 to 97) preoperatively to 40 degrees (24 to 50) after stage 2 and remained at 40 degrees (27 to 53) at last follow-up. Kyphosis remained controlled from 45 degrees (10 to 76) preoperatively to 38 degrees (9 to 61) after stage 2 to 41 degrees (17 to 65) at last follow-up. Complications included superficial wound problems (4 patients), broken rods (2 patients), proximal migration (2 patients), and implant prominence (1 patient). At minimum 2-year follow-up, no patients had lingering neurological complications or instrumentation-bone failure of the GR construct.

CONCLUSIONS

Two-stage GR technique can effectively be utilized in EOS patients with poor bone quality or in the event of intraoperative neurological changes. Satisfactory deformity correction can be obtained and routine serial lengthenings can take place with minimal complications.

LEVEL OF EVIDENCE

Level IV- case series.

Quantifying the ‘law of diminishing returns’ in magnetically controlled growing rods

Aims

Magnetically controlled growing rods (MCGRs) allow non-invasive correction of the spinal deformity in the treatment of early-onset scoliosis. Conventional growing rod systems (CGRS) need repeated surgical distractions: these are associated with the effect of the ‘law of diminishing returns’. The primary aim of this study was to quantify this effect in MCGRs over sequential distractions.

Patients and Methods

A total of 35 patients with a maximum follow-up of 57 months were included in the study. There were 17 boys and 18 girls with a mean age of 7.4 years (2 to 14). True Distraction (TD) was determined by measuring the expansion gap on fluoroscopy. This was compared with Intended Distraction (ID) and expressed as the ‘T/I’ ratio. The T/I ratio and the Cobb angle were calculated at several time points during follow-up.

Results

The mean follow-up was 30 months (6 to 57). There was a significant decrease in the mean T/I ratio over time (convex rod at 3 months 0.81, sd 0.58 vs 51 months 0.17, sd 0.16, p = 0.0001; concave rod at 3 months 0.93, sd 0.67 vs 51 months 0.18, sd 0.15, p = 0.0001). A linear decline of the mean T/I ratios was noted for both convex rods (r2 = 0.90, p = 0.004) and concave rods (r2 = 0.81, p = 0.015) over 51 months. At the 24-month follow-up stage, there was a significant negative correlation between the mean T/I ratio of the concave rod with weight (r = -0.59, p = 0.01), age (r = -0.59, p = 0.01), and BMI of the child (r = -0.54, p = 0.01).

Conclusions

The ‘law of diminishing returns’ is also seen after serial distraction using MCGR. Compared to previously published data for CGRS, there is a gradual linear decline rather than a rapid initial decline in lengthening. In older, heavier children a reduced distraction ratio in the concave rod of the MCGR device is noted over time. Cite this article: Bone Joint J 2017;99-B:1658–64.

Retrieval and clinical analysis of distraction-based dual growing rod constructs for early-onset scoliosis

BACKGROUND CONTEXT

Growing rod constructs are an important contribution for treating patients with early-onset scoliosis. These devices experience high failure rates, including rod fractures.

PURPOSE

The objective of this study was to identify the failure mechanism of retrieved growing rods, and to identify differences between patients with failed and intact constructs.

STUDY DESIGN/SETTING

Growing rod patients who had implant removal and were previously enrolled in a multicenter registry were eligible for this study.

PATIENT SAMPLE

Forty dual-rod constructs were retrieved from 36 patients across four centers, and 34 of those constructs met the inclusion criteria. Eighteen constructs failed due to rod fracture. Sixteen intact constructs were removed due to final fusion (n=7), implant exchange (n=5), infection (n=2), or implant prominence (n=2).

OUTCOME MEASURES

Analyses of clinical registry data, radiographs, and retrievals were the outcome measures.

METHODS

Retrievals were analyzed with microscopic imaging (optical and scanning electron microscopy) for areas of mechanical failure, damage, and corrosion. Failure analyses were conducted on the fracture surfaces to identify failure mechanism(s). Statistical analyses were performed to determine significant differences between the failed and intact groups.

RESULTS

The failed rods fractured due to bending fatigue under flexion motion. Construct configuration and loading dictate high bending stresses at three distinct locations along the construct: (1) mid-construct, (2) adjacent to the tandem connector, or (3) adjacent to the distal anchor foundation. In addition, high torques used to insert set screws may create an initiation point for fatigue. Syndromic scoliosis, prior rod fractures, increase in patient weight, and rigid constructs consisting of tandem connectors and multiple crosslinks were associated with failure.

CONCLUSION

This is the first study to examine retrieved, failed growing rod implants across multiple centers. Our analysis found that rod fractures are due to bending fatigue, and that stress concentrations play an important role in rod fractures. Recommendations are made on surgical techniques, such as the use of torque-limiting wrenches or not exceeding the prescribed torques. Additional recommendations include frequent rod replacement in select patients during scheduled surgeries.

Thoracic Spine Growth Revisited: How Accurate Is the Dimeglio Data?

STUDY DESIGN

Cross-sectional descriptive study.

OBJECTIVE

To describe the normal rate pattern of thoracic spine growth in children without any spinal deformity.

SUMMARY OF BACKGROUND DATA

The knowledge of thoracic spine growth and height is important for growing spine treatment and the decision of final fusion. Currently, pediatric spinal deformity is approached as early onset and late onset with an understanding of the fast growth during the first 5 years of life. The growth data that support this classification is often cited but has not been reconfirmed with follow-up studies.

METHODS

Sagittal computed tomography (CT) reformations of thoracic vertebrae were examined in children without spinal deformity. The sagittal CT cut at the widest canal diameter was identified and the measurements were performed on this image. The length of the thoracic spine was measured from the posterosuperior corner of T1 to the posteroinferior corner of the T12.

RESULTS

One hundred forty-four thoracic CT scans satisfied the inclusion criteria. The analysis of the data identified two break points in the growth velocity; one at the end of the 4th year of life and the other at the beginning of the 12th year. Specifically, growth rate between 1 and 4 years was 1.71 cm/yr, between 4 and 8 years was 0.55 cm/yr, between 8 and 10 was 0.74 cm/yr, between 10 and 12 was 0.69 cm/yr, and between 12 and 16 was 1.61 cm/yr.

CONCLUSION

The results show that in growing children the thoracic spine demonstrates two major growth spurts. The initial growth spurt is between the birth to the end of the fourth year of life and the second is between the 12 and 16 years of age. Between 4 and 12 years there is a steady but slower increase in thoracic height. The findings show that the fastest growth velocity may be limited to a younger age group than previously believed. This data will help guide growth friendly management strategies.

LEVEL OF EVIDENCE

2.

Evaluation of the Modern Luque Trolley Construct for the Treatment of Early-onset Scoliosis Using a Gliding Implant in an Immature Animal Model

STUDY DESIGN

This was an experimental animal study.

OBJECTIVE

To determine biological compatibility, stability, and growth potential of the Trolley Gliding Vehicle (TGV) used in a novel surgical technique for guided spinal growth.

SUMMARY OF BACKGROUND DATA

Current treatments for early-onset scoliosis maintaining spinal growth consist of posteriorly based spinal constructs requiring repetitive lengthening. Such interventions have a high rate of complications. Using a muscle-sparing technique, a modified dual-growing rods construct, and new sliding spinal anchors, we aimed to test a modern Luque Trolley construct in an immature animal model.

MATERIALS AND METHODS

Six matched pairs of 3-month-old lambs were randomized to an observation or a surgical group and were followed for 9 months. The surgical group was subjected to implantation of a modern Luque Trolley construct with the new TGV inserted using a minimally invasive transmuscular technique capturing the spine and the 2 overlapping rods on either side. Physical examinations and imaging were performed at routine intervals, with a subsequent necropsy.

RESULTS

The spines of the study group grew 96% between the instrumented segments compared with the control group without evidence of implant failure. In total, 42% of the fixed anchors (pedicle screws) and 13.90% of the TGV were loose. All 6 animals had some heterotrophic bone formation tracking along the rods (<20%) mainly originating from the distal anchor point. We identified 19 unplanned spontaneous facet arthrodesis out of the 132 mobile facets found between the fixed proximal and distal anchors. An additional 10 facets spontaneously fused proximal to the most proximal instrumented implants.

CONCLUSIONS

Implantation of a modern Luque construct with TGV allows for spinal growth in a nonscoliotic animal model. Implant loosening was likely mechanical as no signs of reactive inflammatory reaction were found. Reduction of heterotrophic ossification and spontaneous facet arthrodesis remains a challenge in the management of immature spine.

The use of magnetically-controlled growing rods to treat children with early-onset scoliosis: early radiological results in 19 children

AIMS

We undertook a prospective non-randomised radiological study to evaluate the preliminary results of using magnetically-controlled growing rods (MAGEC System, Ellipse technology) to treat children with early-onset scoliosis.

PATIENTS AND METHODS

Between January 2011 and January 2015, 19 children were treated with magnetically-controlled growing rods (MCGRs) and underwent distraction at three-monthly intervals. The mean age of our cohort was 9.1 years (4 to 14) and the mean follow-up 22.4 months (5.1 to 35.2). Of the 19 children, eight underwent conversion from traditional growing rods. Whole spine radiographs were carried out pre- and post-operatively: image intensification was used during each lengthening in the outpatient department. The measurements evaluated were Cobb angle, thoracic kyphosis, proximal junctional kyphosis and spinal growth from T1 to S1.

RESULTS

The mean pre-, post-operative and latest follow-up Cobb angles were 62° (37.4 to 95.8), 45.1° (16.6 to 96.2) and 43.2° (11.9 to 90.5), respectively (p < 0.05). The mean pre-, post-operative and latest follow-up T1-S1 lengths were 288.1 mm (223.2 to 351.7), 298.8 mm (251 to 355.7) and 331.1 mm (275 to 391.9), respectively (p < 0.05). In all, three patients developed proximal pull-out of their fixation and required revision surgery: there were no subsequent complications. There were no complications of outpatient distraction.

CONCLUSIONS

Our study shows that MCGRs provide stable correction of the deformity in early-onset scoliosis in both primary and revision procedures. They have the potential to reduce the need for multiple operations and thereby minimise the potential complications associated with traditional growing rod systems. Cite this article: Bone Joint J 2016;98-B:1240-47.

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.

Rib-based Distraction Surgery Maintains Total Spine Growth

BACKGROUND

For children undergoing treatment of early onset scoliosis (EOS) using spine-based distraction, recently published research would suggest that total spine length (T1-S1) achieved after the initial lengthening procedure decreases with each subsequent lengthening. Our purpose was to evaluate the effect of rib-based distraction on spine growth in children with EOS.

METHODS

This was a retrospective multi-center review of 35 patients treated with rib-based distraction (minimum 5 y follow-up). Radiographs were analyzed at initial implantation and just before each subsequent lengthening. The primary outcome was T1-S1 height, which was also analyzed as: Change in T1-S1 height per lengthening procedure, percent of expected age-based T1-S1 growth per lengthening time interval, percent increase in T1-S1 height as compared with postimplantation total spine height, and percent of expected T1-S1 growth based upon patient age at time of lengthening procedure.

RESULTS

Thirty-five patients with a mean age of 2.6 years at initial surgery were studied. Diagnoses included congenital (n=18), syndromic (n=7), idiopathic (n=5), and neuromuscular (n=5). Major Cobb angle was 63.5 degrees and kyphosis was 40.5 degree. Four postoperative time periods were compared: L1 (preoperative first lengthening surgery), L2-L5 (preoperative second lengthening to preoperative fifth lengthening), L6-L10 (preoperative sixth lengthening to preoperative 10th lengthening), L11-L15 (preoperative 11th lengthening to preoperative 15th lengthening). Cobb angle stayed relatively constant for each lengthening period while maximum kyphosis increased. Total spine height was 19.9 cm pre-implantation, 22.1 cm postimplantation, and 28.0 cm by the 15th lengthening (P<0.05). Percent expected T1-S1 growth per lengthening was 62% for L2-L5, 95% for L6-L10, and 52% for L11-L15. As compared with postimplantation spine height, over the course of 15 lengthening procedures, a further 27% increase in spine height was observed. When lengthening procedures were performed when children were under age 5 years, 82% of expected growth was observed; between ages 6 and 10 years, 76% of expected growth was observed; and beyond age 10 years, 14% of expected growth was observed.

CONCLUSIONS

Patients treated with rib-based distraction surgery had an increase in total spine height from 20 cm preimplantation to 28 cm by the 15th lengthening. They maintained greater than 75% of expected age-matched spine growth until age 10 years and lengthening procedures did not appear to follow a law of diminishing returns. Rib-based distraction is an effective means of maintaining spine growth which is likely beneficial for pulmonary development as compared with the natural history of EOS.

LEVEL OF EVIDENCE

Level IV-Therapeutic study, case series.