Comparison between surgical fusion and the growing-rod technique for early-onset neurofibromatosis type-1 dystrophic scoliosis

Vertebral Column Subluxation in Neurofibromatosis Type 1-Associated Dystrophic Scoliosis: A Report of Two Cases and Narrative Review

BACKGROUND AND OBJECTIVE

Neurofibromatosis-1 (NF1) dystrophic scoliosis is a challenging disease to manage surgically, with multiplanar curves progressing rapidly and unpredictably. Conservative management with bracing is often unsuccessful, and many patients necessitate instrumented fusion to halt progression of their curves. In rare cases, patients can present with spontaneous vertebral subluxation, significantly complicating the surgical management of this already complex disease process. The objective here was to describe 2 cases of vertebral subluxation in NF1-associated dystrophic scoliosis along with their surgical corrections and clinical courses.

METHODS

A retrospective review of 2 cases at the authors' institution was performed to describe their preoperative symptom complexes, surgical corrections, and postoperative courses. A narrative review of the literature surrounding NF1-associated dystrophic scoliosis and subluxation is also presented.

RESULTS

Two cases of vertebral subluxation at T4-5 and C7-T1 are presented. Both patients had significant dystrophic features throughout their spines, and halo-gravity traction was unsuccessful in 1 patient and led to vertebral and subclavian artery injuries in the other. One patient underwent an uncomplicated deformity correction with partial vertebral column resection to facilitate his deformity correction. The other patient, after her vascular injuries, ultimately suffered a spinal cord injury after a fall and underwent emergent instrumentation, decompression, and partial vertebral column resection at the site of subluxation, with improvement in her neurological function afterward.

CONCLUSION

Dystrophic scoliosis in NF1 remains a difficult disease to treat, and deformity correction in patients with subluxation is particularly complex. These cases here highlight the unpredictability and possible complications of halo-gravity traction, need for good fixation to facilitate subluxation reduction, high chance of hardware complications and proximal or distal failure, and importance of cooperative management of these patients in conjunction with other surgical services.

Clinical features and surgical treatments of scoliosis in neurofibromatosis type 1: a systemic review and meta-analysis

BACKGROUND

Neurofibromatosis type 1 (NF 1) is an autosomal-dominant tumor predisposition genetic disease affecting approximately 1 in 3000 live births. The condition could present various manifestations ranging from skin abnormalities to neurological tumors. The musculoskeletal system could also be frequently affected, and scoliosis is the most common orthopedic manifestation. Characterized by the early-onset and rapid progression tendency, NF 1-related dystrophic scoliosis presented discrepancies from idiopathic scoliosis in terms of natural history, clinical features, and management outcomes and thus required special attention. In the current study, the authors conducted a systemic review to outline the body of evidence of the natural history, clinical characteristics, surgical outcomes, and surgical complications of NF 1-induced scoliosis, aiming to provide an elucidative insight into this condition.

METHOD

Systemic review and meta-analysis were conducted according to the latest Preferred Reporting Items for Systematic Reviews Meta-Analyses (PRISMA) guidelines. The search was performed in Medline, Embase, and Web of Science Core Collection up to December 27, 2022, using related keywords. Clinical features such as frequencies, segmental involvement, and hereditary information were summarized and described qualitatively. Meta-analysis was conducted using R software and the 'meta' package to yield an overall outcome of efficacy and safety of surgical management, precisely, spinal fusion procedure and growing rods procedure. Corrective rate of Cobb angle, sagittal kyphosis angle, and T1-S1 length post-operative and at the last follow-up was used to evaluate the efficacy, and the occurrence of surgery-related complications was used to evaluate the safety.

RESULT

A total of 37 articles involving 1023 patients were included. Approximately 26.6% of the NF 1 patients would present with scoliosis. Patients tend to develop scoliosis at an earlier age. The thoracic part turned out to be the most affected segment. No obvious correlation between scoliosis and genotype or hereditary type was observed. Both spinal fusion and growing rod surgery have shown acceptable treatment outcomes, with spinal fusion demonstrating better performance in terms of effectiveness and safety. The growing rods technique seemed to allow a better lengthening of the spine. The mainstay post-operative complications were implant-related complications but could be managed with limited revision surgery. Severe neurological deficits were rarely reported.

CONCLUSION

Scoliosis, especially the subtype characterized by dystrophic bony changes, is a significant orthopedic manifestation of NF1. It has an early onset, a tendency to persistently and rapidly progress, and is challenging to deal with. The current review outlines the available evidence from the perspective of natural history, clinical features, and the treatment efficacy and safety of the mainstay surgical options. Patients with NF1 scoliosis will benefit from a better understanding of the disease and evidence based treatment strategies.

Functional and Radiological Outcomes of All-Posterior Surgical Correction of Dystrophic Curves in Patients with Neurofibromatosis Type 1

STUDY DESIGN

A retrospective cohort study.

PURPOSE

To determine outcomes following all-posterior surgery using computed tomography navigation, hybrid stabilization, and multiple anchor point techniques in patients with neurofibromatosis type 1 (NF-1) and dystrophic scoliosis.

OVERVIEW OF LITERATURE

Previous studies favored antero-posterior fusion as the most reliable method; however, approaching the spine anteriorly was fraught with significant complications. With the advent of computer assisted navigation and multiple anchor point method, posterior only approach is reporting successful outcomes.

METHODS

This study included patients who underwent all-posterior surgical deformity correction for dystrophic NF-1 curves. Coronal and sagittal Cobbs angles, apical rotation, and the presence of dystrophic features were evaluated before surgery. Postoperatively, sagittal, coronal, and axial correction, implant position, and implant densities were evaluated. The decline in curve correction and implant-related complications were evaluated at follow-up. Clinical outcomes were evaluated using the Scoliosis Research Society-22 revised index.

RESULTS

This study involved 50 patients with a mean age of 13.6 years and a mean follow-up duration of 5.52 years. With a mean coronal flexibility of 18.7%, the mean apical vertebral rotation (AVR), preoperative coronal Cobb angle, and sagittal kyphosis were 27.4°, 64.01°, and 47.70°, respectively. The postoperative mean coronal Cobb angle was 30.17° (p <0.05), and the sagittal kyphosis angle was 25.4° (p <0.05). The average AVR correction rate was 41.3%. The correction remained significant at the final mean follow-up, with a coronal Cobb angle of 34.14° and sagittal kyphosis of 25.02° (p <0.05). The average implant density was 1.41, with 46% of patients having a high implant density (HID). The HID had a markedly higher mean curve correction (29.30° vs. 38.05°, p <0.05) and a lower mean loss of correction (5.7° vs. 3.8°, p <0.05).

CONCLUSIONS

Utilizing computer-assisted navigation, hybrid instrumentation, and multiple anchor point technique and attaining high implant densities, this study demonstrates successful outcomes following posterior-only surgical correction of dystrophic scoliosis in patients with NF-1.

Bipolar Fusionless Versus Standard Fusion Surgery in Neuromuscular Scoliosis: A Two-center Comparative Study

STUDY DESIGN

Nonrandomized controlled cohort.

OBJECTIVE

To compare early results between bipolar fusionless construct (BFC) and single posterior fusion (SPF) surgery in neuromuscular scoliosis (NMS).

BACKGROUND

Surgical treatments for NMS have traditionally been characterized by high complication rates. A mini-invasive BFC was developed to reduce these risks while maintaining adequate curve reduction. There is, however, a current lack of studies comparing clinical and radiologic perioperative outcomes between both techniques.

METHODS

All patients surgically treated for NMS with to-pelvis construct between 2011 and 2021 at 2 centers were included and divided into 2 groups according to the surgical technique (BFC or SPF). Gender, age, main deformity region, etiology, preoperative and postoperative main curve magnitude and pelvic obliquity, surgery time, estimated blood loss and transfusion rates, length of hospital stay, the magnitude of main curve and pelvic obliquity correction, and early complications were compared. Quantitative data were compared through ANOVA or Mann-Whitney test. Analysis of qualitative outcomes was performed through Fisher exact test and logistic regressions. Kruskal-Wallis test was used to compare complications between groups.

RESULTS

Eighty-nine NMS patients were included: 48 in the SPF group and 41 in the BFC group. Surgery time (203 vs. 241 min), rate (32 vs. 52%) and severity of complications, unplanned returns to the operating room (15 vs. 39%), estimated blood loss (179 vs. 364 cc), and transfusion rates (27 vs. 73%) were lower in the BFC group ( P <0.05). There were no significant differences in age, maturity stage, preoperative curve magnitude, preoperative pelvic obliquity and postoperative curve, and pelvic obliquity correction between groups.

CONCLUSIONS

BFC may be a safer and less invasive option for NMS surgical treatment, resulting in similar curve corrections while significantly decreasing the number and severity of complications as well as intraoperative blood loss when compared with SPF.

LEVEL OF EVIDENCE

Level -lll.

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.

Efficacy of the growing rod technique on kyphotic early-onset scoliosis

Objective

To explore the application of the growing rod (GR) technique in the treatment of kyphotic early-onset scoliosis (KEOS) and analyze its surgical efficacy and safety.

Methods

The clinical data of 30 children with KEOS who received GR treatment at our department between January 2016 and December 2019 were analyzed retrospectively. There were 18 cases with normal kyphosis (normal kyphosis group) and 12 cases with excessive kyphosis (excessive kyphosis group). Both groups received GR treatment, and all patients received anteroposterior and lateral spine X-ray examinations before, after the initial surgery, and at the final follow-up. The surgical conditions and imaging parameters of the two groups were compared, and the complications were recorded.

Results

There was no statistical difference in the Cobb angle of the major curve, apical vertebral translation (AVT), and trunk shift (TS) between the two groups before, after the first surgery, and at the final follow-up (P > 0.05). The Cobb angle of the major curve, the AVT, and the TS in both groups after the first surgery were lower than before the first surgery (P < 0.05), but there was no statistical difference between the two groups (P > 0.05). At the final follow-up, there were increases in both the Cobb angle and the AVT (P < 0.05), while the TS decreased in comparison with findings after the first surgery (P < 0.05). Before and after the first surgery and at the final follow-up appointment, there was a statistical difference in the degree of thoracic kyphosis (TK) between the two groups (P < 0.05), while there was no statistical difference in terms of lumbar lordosis (LL), the proximal junctional angle (PJA), and the distal junctional angle (DJA) (P > 0.05). After the first surgery, TK and LL showed a significant moderate response in both groups (P < 0.05), while there was no significant difference in TK, LL, PJA, and DJA compared with the results at the final follow-up (P > 0.05).

Conclusions

The use of the GR technique can improve kyphosis in KEOS treatment.

Management and surgical outcomes of dystrophic scoliosis in neurofibromatosis type 1: a systematic review

OBJECTIVE

Neurofibromatosis type 1 (NF1) dystrophic scoliosis is an early-onset, rapidly progressive multiplanar deformity. There are few studies on the surgical management of this patient population. Specifically, perioperative morbidity, instrument-related complications, and quality-of-life outcomes associated with surgical management have not been systematically evaluated. In this study, the authors aimed to perform a systematic review on the natural history, management options, and surgical outcomes in patients who underwent NF1 dystrophic scoliosis surgery.

METHODS

A PubMed search for articles with “neurofibromatosis” and either “dystrophic” or “scoliosis” in the title or abstract was performed. Articles with 10 or more patients undergoing surgery for NF1 dystrophic scoliosis were included. Data regarding indications, treatment details, morbidity, and outcomes were summarized and analyzed with descriptive statistics.

RESULTS

A total of 310 articles were identified, 48 of which were selected for full-text review; 30 studies describing 761 patients met the inclusion criteria. The mean age ranged from 7 to 22 years, and 99.7% of patients were younger than 18 years. The mean preoperative coronal Cobb angle was 75.2°, and the average correction achieved was 40.3°. The mean clinical follow-up in each study was at least 2 years (range 2.2–19 years). All patients underwent surgery with the intent of deformity correction. The scoliosis regions addressed were thoracic curves (69.6%) and thoracolumbar (11.1%) and lumbar (14.3%) regions. The authors reported on a variety of approaches: posterior-only, combined anterior-posterior, and growth-friendly surgery. For fixation techniques, 42.5% of patients were treated with hybrid constructs, 51.5% with pedicle screw–only constructs, and 6.0% with hook-based constructs. Only 0.9% of patients underwent a vertebral column resection. The nonneurological complication rate was 14.0%, primarily dural tears and wound infections. The immediate postoperative neurological deficit rate was 2.1%, and the permanent neurological deficit rate was 1.2%. Ultimately, 21.5% required revision surgery, most commonly for implant-related complications. Loss of correction in both the sagittal and coronal planes commonly occurred at follow-up. Five papers supplied validated patient-reported outcome measures, showing improvement in the mental health, self-image, and activity domains.

CONCLUSIONS

Data on the surgical outcomes of dystrophic scoliosis correction are heterogeneous and sparse. The perioperative complication rate appears to be high, although reported rates of neurological deficits appear to be lower than clinically observed and may be underreported. The incidence of implant-related failures requiring revision surgery is high. There is a great need for multicenter prospective studies of this complex type of deformity.

Efficacy and safety for combination of t-EMG with O-arm assisted pedicle screw placement in neurofibromatosis type I scoliosis surgery

Background

Due to the characteristics of neurofibromatosis type I (NF-1) scoliosis, the precise placement of pedicle screws still remains to be a challenge. Triggered screw electromyography (t-EMG) has been proved to exhibit high sensitivity to identify mal-positioned pedicle screws, but no previous study assessed the combination of t-EMG with O-arm-assisted pedicle screw placement in NF-1 scoliosis surgery.

Objective

To evaluate efficacy and safety for combination of t-EMG with O-arm-assisted pedicle screw placement in NF-1 scoliosis surgery.

Materials and methods

From March 2018 to April 2020, sixty-five NF-1 scoliosis patients underwent t-EMG and O-arm-assisted pedicle screw fixation were retrospectively reviewed. The channel classification system was applied to classify the pedicle morphology based on pedicle width measurement by preoperative computed tomography scans. The minimal t-EMG threshold for screw path inspection was used as 8 mA, and operative screw redirection was also recorded. All pedicle screws were verified using a second intraoperative O-arm scan. The correlation between demographic and clinical data with amplitude of t-EMG were also analyzed.

Results

A total of 652 pedicle screws (T10-S1) in 65 patients were analyzed. The incidence of an absent pedicle (channel classification type C or D morphology) was 150 (23%). Overall, abnormal t-EMG threshold was identified in 26 patients with 48 screws (7.4%), while 16 out of the 48 screws were classified as G0, 14 out of the 48 screws were classified as G1, and 18 out of the 48 screws were classified as G2. The screw redirection rate was 2.8% (18/652). It showed that t-EMG stimulation detected 3 unacceptable mal-positioned screws in 2 patients (G2) which were missed by O-arm scan. No screw-related neurological or vascular complications were observed.

Conclusions

Combination of t-EMG with O-arm-assisted pedicle screw placement was demonstrated to be a safe and effective method in NF-1 scoliosis surgery. The t-EMG could contribute to detecting the rupture of the medial wall which might be missed by O-arm scan. Combination of t-EMG with O-arm could be recommended for routine use of screw insertion in NF-1 scoliosis surgery.

Early-Onset Spinal Deformity in Neurofibromatosis Type 1: Natural History, Treatment, and Imaging Surveillance

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Early-onset scoliosis (EOS) or kyphosis is common in patients with neurofibromatosis (NF) and is characterized by rapid progression of deformity.

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Traditional growing rods provide good functional and deformity outcomes in patients with NF and EOS; magnetically controlled growing rods (MCGRs) also provide good deformity correction, although high rates of revision have been reported after their use.

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Among patients with NF type 1 (NF1), morphologic characteristics of the spinal deformity are different in those with paraspinal neurofibromas than in those without paraspinal tumors.

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Patients with NF1 are at low risk for developing malignant peripheral nerve sheath tumors during childhood (<1%) and their lifetime (8% to 12%), and routine imaging surveillance for malignancy in the absence of symptoms should be clinically directed.

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Further investigation is needed to standardize screening for EOS in children with NF1 and to develop guidelines for ideal imaging modalities, including their frequency and a timeline.