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

Rib-to-spine and rib-to-pelvis magnetically controlled growing rods: does the law of diminishing returns still apply?

PURPOSE

The Law Of Diminishing Returns (LODR) has been demonstrated for traditional growing rods, but there is conflicting data regarding the lengthening behavior of Magnetically Controlled Growing Rods (MCGR). This study examines a cohort of patients with early-onset scoliosis (EOS) with rib-to-spine or rib-to-pelvis-based MCGR implants to determine if they demonstrate the LODR, and if there are differences in lengthening behaviors between the groups.

METHODS

A prospectively collected multicenter EOS registry was queried for patients with MCGR with a minimum 2-year follow-up. Patients with rib-based proximal anchors and either spine- or pelvis-based distal anchors were included. Patients with non-MCGR, unilateral constructs, < 3 lengthenings, or missing > 25% datapoints were excluded. Patients were further divided into Primary-MCGR (pMCGR) and Secondary-MCGR (sMCGR).

RESULTS

43 rib-to-spine and 31 rib-to-pelvis MCGR patients were included. There was no difference in pre-implantation, post-implantation and pre-definitive procedure T1-T12 height, T1-S1 height, and major Cobb angles between the groups (p > 0.05). Sub-analysis was performed on 41 pMCGR and 19 sMCGR rib-to-spine patients, and 31 pMCGR and 17 sMCGR rib-to-pelvis patients. There is a decrease in rod lengthenings achieved at subsequent lengthenings for each group: rib-to-spine pMCGR (rho = 0.979, p < 0.001), rib-to-spine sMCGR (rho = 0.855, p = 0.002), rib-to-pelvis pMCGR (rho = 0.568, p = 0.027), and rib-to-pelvis sMCGR (rho = 0.817, p = 0.007). Rib-to-spine pMCGR had diminished lengthening over time for idiopathic, neuromuscular, and syndromic patients (p < 0.05), with no differences between the groups (p > 0.05). Rib-to-pelvis pMCGR neuromuscular patients had decreased lengthening over time (p = 0.01), but syndromic patients had preserved lengthening over time (p = 0.65).

CONCLUSION

Rib-to-spine and rib-to-pelvis pMCGR and sMCGR demonstrate diminished ability to lengthen over subsequent lengthenings.

Outcomes and Safety of Traditional Growing Rod Technique in the Treatment of Early-onset Dystrophic Scoliosis Secondary to Type 1 Neurofibromatosis With Intraspinal Rib Head Dislocation in Children

PURPOSE

The purpose of this study was to investigate the outcomes and safety of traditional growing rod (TGR) in the treatment of early-onset dystrophic scoliosis secondary to type 1 neurofibromatosis (NF1-EOS) with intraspinal rib head dislocation (IRH) in children.

METHODS

From September 2006 to June 2020, 21 patients with NF1-EOS were treated with TGR. The patients comprised 13 boys and 8 girls with a mean age of 7.1±1.5 years. Two patients had IRH-induced nerve injury [American Spinal Injury Association (ASIA) grade D]. No neurological symptoms were found in the other patients. The intraspinal rib proportion, apical vertebral rotation, apical vertebral translation, coronal main thoracic curve, trunk shift, thoracic kyphosis, lumbar lordosis, sagittal balance, and T1-S1 height were measured before and after TGR implantation and at the last follow-up. Complications were also evaluated.

RESULTS

The mean follow-up time was 3.4±2.0 years. An average of 3.1 times (range: 1 to 8 times) lengthening procedures were performed in each patient. The intraspinal rib proportion was significantly lower postoperatively than preoperatively (22±11% vs. 33±18%, respectively; P <0.001), and no significant correction loss was found at the last follow-up (24±12%, P= 0.364). Compared with the measurements before TGR implantation, the major coronal curve and T1-S1 height after TGR implantation and at the last follow-up were significantly different ( P <0.05). Significant correction of apical vertebral translation, thoracic kyphosis, lumbar lordosis, and sagittal balance were noted after TGR implantation, and no significant correction loss was found at the last follow-up ( P >0.05). Ten complications occurred in 7 patients. Two patients with nerve injury recovered after the operation. No neurological complications were found during the follow-up.

CONCLUSIONS

TGR is a safe and effective therapy for NF1-EOS with IRH where there was no direct compression of the spinal cord, which was confirmed by preoperative magnetic resonance imaging. Through this procedure, IRH could be partly removed from the spinal canal.

LEVEL OF EVIDENCE

Level III.

Comparison of surgical interventions for the treatment of early-onset scoliosis: a systematic review and meta-analysis

OBJECTIVE

Several growth-preserving surgical techniques are employed in the management of early-onset scoliosis (EOS). The authors' objective was to compare the use of traditional growing rods (TGRs), magnetically controlled growing rods (MCGRs), Shilla growth guidance techniques, and vertically expanding prosthetic titanium ribs (VEPTRs) for the management of EOS.

METHODS

A systematic review of electronic databases, including Ovid MEDLINE and Cochrane, was performed. Outcomes of interest included correction of Cobb angle, T1-S1 distance, and complication rate, including alignment, hardware failure and infection, and planned and unplanned reoperation rates. The percent changes and 95% CIs were pooled across studies using random-effects meta-analysis.

RESULTS

A total of 67 studies were identified, which included 2021 patients. Of these, 1169 (57.8%) patients underwent operations with TGR, 178 (8.8%) Shilla growth guidance system, 448 (22.2%) MCGR, and 226 (11.1%) VEPTR system. The mean ± SD age of the cohort was 6.9 ± 1.2 years. The authors found that the Shilla technique provided the most significant improvement in coronal Cobb angle immediately after surgery (mean [95% CI] 64.3% [61.4%-67.2%]), whereas VEPTR (27.6% [22.7%-33.6%]) performed significantly worse. VEPTR also performed significantly worse than the other techniques at final follow-up. The techniques also provided comparable gains in T1-S1 height immediately postoperatively (mean [95% CI] 10.7% [8.4%-13.0%]); however, TGR performed better at final follow-up (21.4% [18.7%-24.1%]). Complications were not significantly different among the patients who underwent the Shilla, TGR, MCGR, and VEPTR techniques, except for the rate of infections. The TGR technique had the lowest rate of unplanned reoperations (mean [95% CI] 15% [10%-23%] vs 24% [19%-29%]) but the highest number of planned reoperations per patient (5.31 [4.83-5.82]). The overall certainty was also low, with a high risk of bias across studies.

CONCLUSIONS

This analysis suggested that the Shilla technique was associated with a greater early coronal Cobb angle correction, whereas use of VEPTR was associated with a lower correction rate at any time point. TGR offered the most significant height gain at final follow-up. The complication rates were comparable across all surgical techniques. The optimal surgical approach should be tailored to individual patients, taking into consideration the strengths and limitations of each option.

Comparison of Early Definitive Fusion and Traditional Growing Rods in Early-onset Dystrophic Scoliosis in Neurofibromatosis Type 1: A Preliminary Report

BACKGROUND

Early definitive spinal fusion (EF) has been widely recommended to avoid spinal deformity progression for early-onset scoliosis (EOS) with neurofibromatosis type 1 (NF-1). In contrast, growing rod (GR) procedure has recently been recommended for EOS associated with the dystrophic type NF-1. However, no studies have compared the surgical outcomes between EF and GR procedure for EOS with NF-1. The purpose of this study was to compare the surgical outcomes of EF versus GR for early onset and dystrophic scoliosis with NF-1.

METHODS

This was a retrospective multicenter study; 26 EOS patients with dystrophic type of NF-1 who underwent EF (16 patients) or GR (10 patients) were investigated. We compared age at first surgery, fused levels, total number of surgeries, coronal major curve, complication rates, spinal height (T1-T12 and T1-S1 length), and forced vital capacity between the 2 groups.

RESULTS

The mean age at first surgery was 7.3 years in the EF and 5.8 years in the GR (P<0.05). The mean follow-up period was 12.8 and 10.5 years, respectively. The 2 groups did not show significant differences in preoperative major Cobb angle (75.1 vs. 83.1 degrees), complication rate (53% vs. 60%), and increase rate of T1-T12 (20.0% vs. 30.4%). However, significant differences (P<0.05) were recognized in fusion segments (13.9 vs. 15.8), total numbers of surgery (2.6 vs. 10.1), correction rate of major curve (59.0% vs. 40.6%), increase rate of T1-S1 (19.0% vs. 33.9%), body height at final follow-up (151 vs. 142 cm), and forced vital capacity at final follow-up (2.23 vs. 1.46 L).

CONCLUSIONS

Early fusion is still a viable option for progressive EOS with dystrophic type of NF-1 even in the growth-friendly era. Surgeons should consider the best procedure for each patient taking into account the severity of dystrophic change when treating EOS with NF-1.

LEVEL OF EVIDENCE

Level IV.

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.

Evolution of the postoperative sagittal spinal profile in early-onset scoliosis: is there a difference between rib-based and spine-based growth-friendly instrumentation?

OBJECTIVE Although the vertical expandable prosthetic titanium rib (VEPTR) and growing rod instrumentation (GRI) encourage spinal growth via regular lengthening, they can create different results because of their different fixation patterns and mechanisms in correcting scoliosis. Previous studies have focused comparisons on coronal plane deformity with minimal attention to the sagittal profile. In this retrospective study, the authors aimed to compare the evolution of the sagittal spinal profile in early-onset scoliosis (EOS) treated with VEPTR versus GRI. METHODS The data for 11 patients with VEPTR and 22 with GRI were reviewed. All patients had more than 2 years' follow-up with more than 2 lengthening procedures. Radiographic measurements were performed before and after the index surgery and at the latest follow-up. The complications in both groups were recorded. RESULTS Patients in both groups had similar diagnoses, age at the index surgery, and number of lengthening procedures. The changes in the major coronal Cobb angle and T1-S1 spinal height were not significantly different between the 2 groups. Compared with the GRI group, the VEPTR group had less correction in thoracic kyphosis (23% ± 12% vs 44% ± 16%, p < 0.001) after the index surgery and experienced a greater correction loss in thoracic kyphosis (46% ± 18% vs 11% ± 8%, p < 0.001) at the latest follow-up. Although the increase in the proximal junctional angle was not significantly different (VEPTR: 7° ± 4° vs GRI: 8° ± 5°, p = 0.569), the incidence of proximal junctional kyphosis was relatively lower in the VEPTR group (VEPTR: 18.2% vs GRI: 22.7%). No significant changes in the spinopelvic parameters were observed, while the sagittal vertical axis showed a tendency toward a neutral position in both groups. The overall complication rate was higher in the VEPTR group than in the GRI group (72.7% vs 54.5%). CONCLUSIONS The VEPTR had coronal correction and spinal growth results similar to those with GRI. In the sagittal plane, however, the VEPTR was not comparable to the GRI in controlling thoracic kyphosis. Thus, for hyperkyphotic EOS patients, GRI is recommended over VEPTR.