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Does spinal deformity correction of non-dystrophic scoliosis in neurofibromatosis type I with one-stage posterior pedicle screw technique produce outcomes similar to adolescent idiopathic scoliosis?
Accepted Manuscript Title: Does spinal deformity correction of non-dystrophic scoliosis in neurofibromatosis type-1 with one-stage posterior pedicle screw technique produce outcomes similar to adolescent idiopathic scoliosis? Author: Qiunan Lyu, Chunguang Zhou, Yueming Song, Limin Liu, Lei Wang, Zhongjie Zhou PII: DOI: Reference:
S1529-9430(17)30279-6 http://dx.doi.org/doi: 10.1016/j.spinee.2017.06.011 SPINEE 57351
To appear in:
The Spine Journal
Received date: Revised date: Accepted date:
6-3-2017 2-5-2017 16-6-2017
Please cite this article as: Qiunan Lyu, Chunguang Zhou, Yueming Song, Limin Liu, Lei Wang, Zhongjie Zhou, Does spinal deformity correction of non-dystrophic scoliosis in neurofibromatosis type-1 with one-stage posterior pedicle screw technique produce outcomes similar to adolescent idiopathic scoliosis?, The Spine Journal (2017), http://dx.doi.org/doi: 10.1016/j.spinee.2017.06.011. This is a PDF file of an unedited manuscript that has been accepted for publication. As a service to our customers we are providing this early version of the manuscript. The manuscript will undergo copyediting, typesetting, and review of the resulting proof before it is published in its final form. Please note that during the production process errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain.
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Title: Does Spinal Deformity Correction of Non-dystrophic Scoliosis in
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Neurofibromatosis Type-1 with One-stage Posterior Pedicle Screw Technique
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Produce Outcomes Similar to Adolescent Idiopathic Scoliosis?
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Authors’ full names: Qiunan Lyu,M.D.; Chunguang Zhou*,PhD; Yueming Song,PhD;
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Limin Liu,PhD;Lei Wang,PhD; Zhongjie Zhou,PhD;
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Institution: Department of orthopedics surgery, West China Hospital, Sichuan
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University, China
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First Author：Qiunan Lyu
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Email: [email protected].
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Corresponding Author: Chunguang Zhou.
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E-mail:
;
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Tel: +86 028 85422430;
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Fax: +86 028 85423326;
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Funding Sources/Benefits received: The study was funded by the National Natural
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Science Foundation of China (Grant No.81401760). No benefits in any form have
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been or will be received from any commercial party related directly or indirectly to
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the subject of this article.
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Device Status: The Manuscript submitted does not contain information about
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medical device(s)/drug(s).
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Abstract
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Background Context: Efficacy of one-stage posterior pedicle screw instrument used in the treatment
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of non-dystrophic scoliosis in neurofibromatosis type-1(NF-1) is unknown. And there is no study that
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has directly compared the results of spinal deformity correction between non-dystrophic scoliosis in
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NF-1 and adolescent idiopathic scoliosis (AIS).
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Purpose: To study the efficacy of one-stage posterior pedicle screw instrument used in the treatment of
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non-dystrophic scoliosis in NF-1 and compare non-dystrophic scoliosis in NF-1 with matched AIS to
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illustrate the differences.
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Study Design: Retrospective case control study.
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Patient Sample: Fifteen patients with non-dystrophic scoliosis in NF-1 and fifteen patients with AIS
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underwent one-stage posterior surgery with pedicle screw system.
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Outcome Measures: Preoperative and Postoperative whole-spine radiographs were used to determine
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coronal and sagittal Cobb angles. And the distance between C7 plumb line (C7PL) and center sacral
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vertical line (CSVL), sagittal vertebral axis (SVA) were measured to assess spinal balance. Scoliosis
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Research Society (SRS)-22 questionnaire was used to evaluate functional outcomes.
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Methods: We matched 15 patients with non-dystrophic scoliosis in NF-1 with AIS patients (ratio, 1:1)
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for age, sex, and degree of major deformity. Overall mean age was 13.4±2.0 and 14.0±2.1 years,
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respectively. The NF-1 group consisted of 10 males and 5 females, and the AIS group consisted of 9
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males and 6 females. Mean follow-up was 37.6±3.9 and 33.5±5.0 months, respectively. The AIS group
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underwent EV or EV+1 fusion. The NF-1 group underwent EV+1, 2, or 3 fusion. Both coronal and
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sagittal Cobb angle, trunk balance, operative time, blood loss, fusion levels, length of stay and scores
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on the Scoliosis Research Society (SRS)-22 questionnaire were compared between two groups. The 2
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study was supported by the National Natural Science Foundation of China (Grant No.81401760). There
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were no study-specific conflict of interest–associated biases.
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Results: The preoperative main curve magnitude was similar between the two groups, however the
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flexibility of NF-1 group tended to be less than AIS group. The rate of correction of the main curve
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obtained surgically (79.8% compared with 81.1%) was similar in the NF-1 and AIS groups. There were
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no significant difference in the loss of correction between two groups(P>0.05).And there were no
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significant differences between the groups in operative time, blood loss, fusion levels, screw number,
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length of stay, trunk balance and scores on the SRS-22 . There were no serious complications related to
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surgery in both groups.
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Conclusion: Despite the differences in preoperative flexibilities and fusion strategies, non-dystrophic
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scoliosis in NF-1 can be treated with satisfied correction rate and progression rate similar to
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comparable AIS by using one-stage posterior pedicle screw technique. Dural ectasia or thin pedicles in
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non-dystrophic scoliosis could make pedicle screw placement challenging.
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Keywords: spinal deformities; non-dystrophic scoliosis; adolescent idiopathic scoliosis; pedicle screw;
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Introduction
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Neurofibromatosis (NF) is one of the most common autosomal dominant hereditary disorder
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which mainly affects cells derived from the neural crest. Usually, NF can be divided into different types, 3
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and Type 1 (NF-1) also known as von Recklinghausen is the most frequent one. It was reported that
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about 10%-60% NF-1 patients were complicated by spinal deformities, with scoliosis being the most
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common skeletal complication. [1, 2]
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It is a major challenge for spine surgeons to treat spinal deformities in NF-1 with the high
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incidence of pseudoarthrosis and curve progression. Normally, coronal plane deformity of the thoracic
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and/or lumbar spine can be divided into non-dystrophic and dystrophic scoliosis based on whether the
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curve contain 3 or more dystrophic features on the plain radiographs. [3] As the two types of scoliosis
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in NF-1 differ dramatically both in terms of management and prognosis, a clear distinction between
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them is extremely important. [4] Although a non-dystrophic scoliosis is regarded less severe than a
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dystrophic scoliosis and is similar to a normal idiopathic scoliosis, it usually present earlier and
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progress more easily with a higher pseudarthrosis rate after spinal fusion than an idiopathic one. [5, 6]
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So far, there are no established practice guidelines for the treatment of non-dystrophic scoliosis
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associated with NF-1. Different sorts of instruments such as hooks, sublaminar wires and hybrid
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systems have been applied to correct them ,and occasionally combined anterior-posterior surgeries has
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been used in some serious cases with these techniques. [7, 8, 9]And non-dystrophic scoliosis treated
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with these techniques usually progressed more easily and had higher rate of pseudarthrosis after spinal
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fusion than AIS. [5, 6] However, all these results were obtained from cohort study using hooks,
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sublaminar wires and hybrid systems.
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Right now, pedicle screw instrument are widely used to correct scoliosis. In our department, we
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use posterior pedicle screw instrument to correct both non-dystrophic scoliosis associated with NF-1
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and AIS. It is observed that patients with non-dystrophic scoliosis who were treated with one-stage
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posterior pedicle screw instrument haven’t progressed significantly after surgery and the prognosis of 4
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them has been similar to AIS patients. But there is no study has directly compared the results of
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surgical treatment between patients with non-dystrophic scoliosis associated with NF-1 and those with
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AIS. Therefore, the goal of this study was to evaluate the efficacy of one-stage posterior pedicle screw
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instrument used in the treatment of non-dystrophic scoliosis and compared the results of surgical
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treatment for non-dystrophic scoliosis patients with matched AIS patients to identify whether the
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differences in therapeutic efficacy and prognosis still remain.
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Methods
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We retrospectively reviewed the records of patients with NF-1 non-dystrophic scoliosis who were
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treated from 2009 to 2014 at our department. Inclusion criteria for the NF-1 group were as
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follows:(1)patients who presented with two or more diagnostic criteria of NF-1; [10] (2)patients with
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scoliosis but did not have dystrophic features; (3)patients who underwent spinal surgery with one-stage
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posterior segmental pedicle screw technique; (4)patients who had at least 2 years of postoperative
13
follow-up. We also reviewed records of patients with AIS who underwent spinal fusion using the same
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technique at the database of our department. A one-to-one patient match was carried out based on curve
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type, magnitude, sex and age to the patients with NF-1. They were required to have a minimum 2-year
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follow-up. The patients with AIS were selected by a doctor who manage our database and not by
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authors of the study. Factors not mentioned above were not taken into account in the matching process.
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Thus, there were 15 patients with NF-1 non-dystrophic scoliosis and 15 patients with AIS included
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in our study. The NF-1 group consisted of 10 males and 5 females, and the AIS group consisted of 9
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males and 6 females. Age at surgery was 13.4±2.0 years in NF-1 patients (ranged from 10 to 17 years)
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and 14.0±2.1 years in AIS patients (ranged from 11 to 18 years). Risser grade at surgery was 2.2±2.0 in
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NF-1 group and 2.3±1.7 in AIS group. Mean length of follow-up after spinal surgery was 37.6±3.9 5
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months in NF-1 group and 33.5±5.0months in AIS group. The spinal deformities in NF-1 group
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included 10 cases of thoracic scoliosis (apical vertebra at T11 or above), three cases of thoracolumbar
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scoliosis (apical vertebra at T12 or L1) and two cases of lumbar scoliosis(apical vertebra at L2 and
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below).And curve types in AIS group were the same as those in NF-1 group. There was no significant
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difference in average age, Risser grade, sex distribution or curve type between both groups (Table 1).
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All patients underwent clinical examination which includes thorough neurologic evaluation and
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radiological examination before surgery. Standard standing plain radiographs of the whole spine
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(posterior-anterior and lateral positions) were used to measure coronal and sagittal curves by the Cobb
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method. And the distance between C7 plumb line (C7PL) and center sacral vertical line (CSVL),
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sagittal vertebral axis (SVA) were measured to assess spinal balance. Side-bending radiographs of
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whole spine were used to evaluate spinal coronal flexibility. The flexibility of the coronal curves was
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calculated by subtracting the magnitude of the preoperative bending Cobb angle from the magnitude of
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the preoperative upright coronal Cobb angle and then dividing by the preoperative coronal Cobb angle.
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[11] Three-dimensional computed tomography (3D-CT) was used to evaluate severity of pedicle
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deformity for some NF-1 patients preoperatively. It was regarded as an indicator of nonunion or
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pseudoarthrosis that loss of correction is 10°or more. [12, 13, 14] Magnetic resonance imaging (MRI)
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of whole spine was used to assess spinal cord condition in all NF-1 patients and some AIS patients
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before surgery. The following time were analyzed: preoperative, immediate postoperative and latest
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follow-up.
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The Scoliosis Research Society (SRS)-22 scores which contains five domains (including pain,
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general self-image, function/activity, satisfaction and mental health) were used to evaluate the
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functional outcomes. Each domain has a score ranging from 1 to 5 and 5 is the most favorable. [15] 6
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All surgeries in both groups were performed by two senior surgeons in our department with
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somatosensory and motor evoked potential monitoring (SSEP and MEP). Posterior correction and
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fusion with segmental pedicle screw instrumentation was performed for all patients in two groups.
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Patients were placed in the prone position on operating table and a posterior median incision was made.
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In AIS group, 7 patients underwent fusion from upper end vertebra to lower end vertebra (EV) and 8
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patients underwent fusion from one level proximal to the upper end vertebra to one level distal to the
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lower end vertebra (EV+1). In NF-1 group, 7 Patients underwent fusion from one level proximal to the
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upper end vertebra to one level distal to the lower end vertebra (EV+1), 4 Patients underwent fusion
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from two level proximal to the upper end vertebra to two level distal to the lower end vertebra (EV+2),
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and 4 Patients underwent fusion from three level proximal to the upper end vertebra to three level distal
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to the lower end vertebra (EV+3). For some NF-1 patients, pedicles expected to receive screw insertion
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were evaluated carefully in 3D-CT before surgery and screw insertion in surgical segment was assisted
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by three-dimension navigation device during surgery. Facetectomies were performed in some serious
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patients and gradual correction was done with a combination of translation/derotation maneuvers.
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Thoroughly decortication was performed and the residual autogenous bone was used for posterior and
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lateral fusions. Allogeneic grafts was used for patients who had not enough residual bone.
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Postoperatively, all patients were braced for an average of 3 months, and then gradually weaned off the
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brace.
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All data were analyzed by using SPSS software (version 22.0; IBM Corp., Armonk, NY, USA).
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All values are presented as mean ± standard deviation. The Quantitative data were analyzed by using
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Student’s t test and Man-Whitney U test depending on whether they followed a normal distribution.
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Categorical data were analyzed by using the χ2 test or Fisher’s exact test. 7
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Results
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The operative notes and the radiological results of surgery were evaluated including complications
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related to the surgical procedure. The mean intraoperative blood loss was 796.7±259.4 ml in NF-1
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group and 776.7±248.5 ml in AIS group (P>0.05).The average length of stay was 15.5±3.9 days in
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NF-1 group and 14.2±3.6 days in AIS group (P>0.05).The mean operation time was 242.3±39.5
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minutes in NF-1 group and 230.7±37.3 minutes in AIS group (P>0.05).
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In the NF-1 group, dural ectasia was identified in 1 patient and thin pedicles were identified in 8
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patients on the preoperative MRIs and 3D-CT scans (Fig. 1). Patients in NF-1 group had 10.5±2.9
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levels instrumented on average, whereas patients in AIS group had 9.8±2.0 levels instrumented on
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average (P>0.05).The number of inserted screws was 11.6±2.7 on average in NF-1 group and 10.9±2.0
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on average in AIS group (P>0.05).Table 1 lists the patient operative notes.
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Patients in both groups had nearly identical preoperative mean major curve cobb angle in coronal
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plane which was 57.3±11.4°in NF-1 group and 58.5±6.4°in AIS group (P>0.05). The flexibility of
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NF-1 group tended to be less than AIS group, which was 36.5±12.5 % and 47.1±14.3 % respectively
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(P<0.05). The mean Cobb angle in coronal plane of scoliosis was reduced to 11.8±6.2°in NF-1 group
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and 11.3±5.4°in AIS group immediately after surgery (P>0.05). Thus, mean initial curve correction was
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79.8±10.7% in NF-1 group and 81.1±8.0% in AIS group (P>0.05). At latest follow-up, the mean Cobb
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angle of scoliosis was 14.6±7.2°in NF-1 group and 13.8±6.7°in AIS group, which indicated the mean
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correction rate dropped to 74.9±13.6% in NF-1 group and 76.8±10.6% respectively(P>0.05). Fig. 2
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depicts the preoperative, postoperative and last follow-up posterior-anterior radiographs of a
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non-dystrophic scoliosis patient with NF-1 and an AIS patient.
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The mean preoperative sagittal plane deformity was 36.7±7.4°in NF-1 group and 33.6±6.8°in AIS 8
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group (P>0.05).The mean Cobb angle in sagittal plane was reduced to 16.9±3.9°in NF-1 group and
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16.3±2.7°in AIS group immediately after surgery (P>0.05).At last follow-up, the mean Cobb angle of
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kyphosis rose to 18.1±4.6°in NF-1 group and 17.3±3.0°in AIS group (P>0.05).There was no patient
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who had sagittal Cobb angle exceeding 40°at the last follow-up in both group. Fig. 3 depicts the
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preoperative, postoperative and last follow-up lateral radiographs of a non-dystrophic scoliosis patient
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with NF-1 and an AIS patient.
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The average preoperative distance between C7PL and CSVL was 17.0±12.1 mm in NF-1 group
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and 14.5±11.6 mm in AIS group (P>0.05).And it improved to 11.3±4.9mm in NF-1 group and 10.5±5.9
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mm in AIS group at the last follow up (P>0.05).The average preoperative SVA was 26.5±18.4 mm in
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NF-1 group and 28.9±19.6 mm in AIS group (P>0.05).And it reduced to 16.8±12.0 mm in NF-1 group
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and 19.1±12.1 mm in AIS group at the last follow up (P>0.05).Table 2 lists radiological results of
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surgery in both group. Fig. 4 depicts the preoperative and postoperative photographs of a
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non-dystrophic scoliosis patient with NF-1 and an AIS patient.
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There were 7 patients in NF-1 group who underwent fusion from one level proximal to the upper
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end vertebra to one level distal to the lower end vertebra (EV+1) and 8 patients from two or three levels
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proximal to the upper end vertebra to two or three levels distal to the lower end vertebra (EV+2 or
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3).The correction rate of coronal cobb angle was 77.9±11.1% in EV+1 group and 80.9±11.3% in EV+2
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or 3 group immediately after surgery(P>0.05). And it dropped to 72.0±15.5% in EV+1 group and
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77.5±12.1% in EV+2 or 3 group at the latest follow-up(P>0.05). The mean intraoperative blood loss
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was 714.3±195.2 ml in EV+1 group and 868.8±298.7 ml in EV+2 or 3 group (P>0.05). The mean
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operation time was 230.7±26.2 minutes in EV+1 group and 252±47.7 minutes in EV+2 or 3 group
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(P>0.05). Whereas posterior fusion length and screw number in EV+2 or 3 group were significantly 9
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higher than those in EV+1 group (P<0.05). Table 3 lists information of patients who underwent
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different correction strategies in NF-1 group.
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All patients in both groups completed the SRS-22 functional outcomes instrument preoperatively
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and postoperatively. There was no significant difference in scores between the two groups before
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surgery. At the latest follow-up, the non-dystrophic and AIS groups had similar scores in the pain (4.4
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compared with 4.5), self-image (4.5 compared with 4.5), function (4.7 compared with 4.6) and mental
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health (4.6 compared with 4.7) domains (P>0.05). And both groups showed improvement in each
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domain. The two groups also had similar scores in the postoperative domain of satisfaction (4.8
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compared with 4.7) (P>0.05).
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No patient had lost curve correction more than 10°or experienced persistent pain or tenderness
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along the fusion areas in both group. There was no pseudoarthosis or nonunion at the latest follow-up.
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No additional revision surgeries were performed in both groups at the latest follow-up, whereas
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whether revision surgery will be performed in the future depends on the continued follow-up results.
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No patient had a deep wound infection that required revision surgery. One patient in NF-1 group
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experienced a transient weakness in the left lower limb which fully recovered after administration of
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methylprednisolone and neurotrophic medicine. There was no intraoperative cerebrospinal fluid leak in
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both groups. No instrumentation complications were found in both groups, such as broken screws,
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broken rods and screw dislodgement.
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Discussion
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So far, there are few peer-reviewed articles which have presented detailed radiographic outcomes
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of treatment of spinal deformity in patients with non-dystrophic scoliosis. Although few researches
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have reported differences in therapeutic efficacy and prognosis between idiopathic and non-dystrophic 10
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curves, to our certain knowledge, there is no study that has directly compared the results of spinal
2
deformity correction between these two kinds of patients. Before the match, we planned to make
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flexibility as one of the matching factors. However, in the matching process, it was found that the
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flexibilities of non-dystrophic scoliosis tended to be less than AIS. As a result, it couldn’t be done to
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match AIS patients with similar flexibilities. So an age, sex, curve type and magnitude matched
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comparison between AIS and non-dystrophic scoliosis was performed by us.
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It has been assumed that the progression and high pseudarthrosis rate of a non-dystrophic curve
8
can be attributed to its natural course. There was an author who concluded four patterns for the natural
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history of a spinal deformity in patients with NF-1. [16] Crawford [6, 17] indicated that a
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non-dystrophic curve was possible to transform into a dystrophic one in natural process. Abubakar et al
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[3] also observed that some non-dystrophic curves were able to transform into dystrophic ones by
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acquiring various dystrophic morphologic features and defined it as modulation. In their study, 81% of
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the spinal deformities that developed before 7 years of age showed evidence of modulation. Besides,
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they believed if a non-dystrophic curve acquired three or more dystrophic features, it was likely to
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progress afterwards.
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There have been authors who believe that the progression and failure of fusion in a non-dystrophic
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scoliosis is related to difficulties in instrumentation. It was reported that stable and strong
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instrumentation couldn’t be achieved easily with the poor and osteoporotic bone stock in NF-1 patients.
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[18] And particular changes like vertebral scalloping and thin pedicle which were caused by dural
20
extasia usually made pedicle screw placement challenging and weakened the fixation of posterior
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instrumentation (Fig. 1). Furthermore, some studies suggested that spinal deformities in NF-1
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sometime progressed even if the arthodesis was completed. [19, 20] To sum up, scoliosis in NF-1 has 11
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been difficult to treat as failure of fixation and loss of correction have been frequent occurrence.
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However, these conclusions were mainly concluded from some outdated techniques.
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In previous studies, non-dystrophic scoliosis in NF-1 was usually treated with the Harrington or
4
Luque technique which has inadequate fixation strength. The rate of internal fixation failure and curve
5
correction loss were high. Thus, it was suggested that serious non-dystrophic scoliosis should be treated
6
with combined anterior release and bone grafting followed by posterior spine fusion with the use of
7
instrumentation. [7, 21] In the past decade, posterior hook-rod-based instrumentation has been used in
8
the treatment of non-dystrophic scoliosis. [1, 19, 22] And the post-operative coronal correction has
9
ranged from 61.3% to 69.2%, which has suggested that posterior fusion alone can be used in treating
10
serious non-dystrophic curves and gain an acceptable outcome. However, this instrumentation still has
11
many limitations compared with pedicle screw. It was reported that pedicle screw fixation demonstrates
12
better corrective ability compared to traditional hook/hybrid instrumentation in the treatment of AIS
13
patients. [23, 24] Besides, pedicle screw instrumentation could reduce blood loss, make anterior
14
surgery unnecessary and cut down total cost. [25] Thus, it is of great value to study the efficacy of
15
pedicle screw instrumentation in the treatment of NF-1 non-dystrophic scoliosis.
16
In our study, spinal deformity correction in NF-1 group was similar to AIS group. The results
17
reported here showed that curve correction in AIS group was similar to those been reported before. [26]
18
And curve correction in our NF-1 group was better than other non-dystrophic scoliosis patients treated
19
by hook-rod-based instrumentation. [1, 19, 22] The study also showed that there were no apparent
20
progression of deformity with the pedicle screw system at the latest follow-up in both groups. And the
21
mean correction loss rate was similar between the two groups. Besides, there was no significant
22
difference in the average length of stay, blood loss and operative time between both groups. Therefore, 12
Page 12 of 22
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the results suggested that posterior pedicle screw fixation and fusion alone could yield same
2
satisfactory outcomes in both AIS and non-dystrophic scoliosis.
3
As for trunk balance, mean distance between C7PL and CSVL and mean SVA were both
4
satisfactory at the latest follow-up in NF-1 group and AIS group, and there was no patient get trunk
5
imbalance. Many previous articles studied the principles of retaining trunk balance and the concepts of
6
aesthetics AIS patients. [27, 28] Although patients with scoliosis in NF-1 have not been studied in this
7
area, it is also important to regain or maintain total trunk balance for them as there are many
8
similarities between AIS and NF-1 scoliosis.
9
The SRS-22 questionnaire has been applied to evaluating changes in patients with scoliosis who
10
undergo a surgery. [15] In our study, five domains of SRS-22 including pain, general function,
11
self-image and mental health scores were similar between the two groups, which suggests that patients
12
with non-dystrophic scoliosis and those with AIS can obtain parallel clinical outcomes with posterior
13
pedicle screw fixation and fusion.
14
At present, there have been many articles about selection of fusion and instrumentation levels in
15
AIS, however fusion strategy for scoliosis in NF-1 has not been widely discussed. [29, 30] There is no
16
accepted classification system or standard surgical decision-making plan for non-dystrophic scoliosis in
17
NF-1.So the selection of fusion and instrumentation levels for non-dystrophic scoliosis is more difficult
18
than AIS. In our study, patients in AIS group underwent EV or EV+1 fusion. And patients in NF-1
19
group underwent EV+1, 2 or 3 fusion in order to achieve satisfactory correction and prevent curve
20
progression after surgery. There was no decompensation or adding-on in the NF-1 group. And our
21
results showed that correction rate and correction loss rate had no difference in EV+1 group and EV+2
22
or 3 group in NF-1 patients. It suggests that EV+1 fusion strategy is enough for non-dystrophic 13
Page 13 of 22
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scoliosis in NF-1.However, as it is widely accepted that fewer segments should be fused to preserve
2
more lumbar mobility and prevent early degeneration of distal intervertebral disc, fusion strategies
3
which could preserve one or two more mobile segments than EV+1 fusion should be taken in to
4
consideration in the future studies.
5
Although the fusion strategy of AIS group could preserve more segments than the one of
6
non-dystrophic scoliosis group, patients in both groups had almost identical average posterior fusion
7
length and screw number. After reviewing the radiographs of NF-1 patients, we found that curves in
8
non-dystrophic patients tend to be sharply angulated curvature and contain less segments. In other
9
words, curves of AIS usually involve more segments than curves of non-dystrophic scoliosis if their
10
magnitudes are similar. As a result, in spite of different fusion strategies in both groups, the average
11
posterior fusion length and screw number were alike in two groups as curve magnitudes of both groups
12
had no significant differences.
13
It has been widely believed that complications after surgery in NF-1 patients are much common
14
and serious than those in AIS patients. Previous studies suggested that the incidence of pseudoarthrosis
15
after spinal fusion in NF-1 patients with dystrophic or non-dystrophic spinal deformities was higher
16
than in patients with AIS, and the incidence ranged from 15% to 47%. [5, 31] And a neurologic deficit
17
in patients with NF-1 was easier to be encountered than in patients with AIS, as NF-1 scoliosis patients
18
tended to present spinal cord compression secondary to spinal deformity, rib penetration into the spinal
19
canal and intraspinal tumors. [32, 33] However, our study showed there was no fusion failure in both
20
group and main complications had no significant difference between two groups.
21
Conclusions
22
In conclusion, despite the differences in preoperative flexibilities and fusion strategies, 14
Page 14 of 22
1
non-dystrophic scoliosis in NF-1 can be treated with satisfied clinical and radiographic outcomes
2
similar to comparable AIS by using one-stage posterior pedicle screw technique. Dural ectasia or thin
3
pedicles in non-dystrophic scoliosis could make pedicle screw placement challenging. We hoped that
4
this improved awareness could help improve the safety and efficacy of surgical management for
5
patients with non-dystrophic scoliosis. However, the number of patients was small and the preoperative
6
flexibilities and fusion strategies of the two groups were different in the study. So, further large-scale
7
and well-designed studies are needed to draw a more convincing conclusion and optimize the surgical
8
management for non-dystrophic scoliosis.
9 10
References
11
1.
12
neurofibromatosis type 1. Report of 12 cases. J Neurosurg. 2002;97(3 Suppl):310-6.
13
2.
14
Spine (Phila Pa 1976). 1992;17(8 Suppl):S244-8.
15
3.
16
deformities in patients with neurofibromatosis type 1. Spine (Phila Pa 1976). 2000;25(1):69-75.
17
4.
18
dystrophic features in patients with type 1 neurofibromatosis and spinal deformities increase the risk of
19
surgery? Spine (Phila Pa 1976). 2013;38(18):1595-601.
20
5.
21
Orthop Relat Res. 1989;(245):24-8.
22
6.
Halmai V, Doman I, de Jonge T, Illes T. Surgical treatment of spinal deformities associated with
Akbarnia BA, Gabriel KR, Beckman E, Chalk D. Prevalence of scoliosis in neurofibromatosis.
Durrani AA, Crawford AH, Chouhdry SN, Saifuddin A, Morley TR. Modulation of spinal
Lykissas MG, Schorry EK, Crawford AH, Gaines S, Rieley M, Jain VV. Does the presence of
Shufflebarger HL. Cotrel-Dubousset instrumentation in neurofibromatosis spinal problems. Clin
Crawford AH. Neurofibromatosis in children. Acta orthopaedica Scandinavica Supplementum. 15
Page 15 of 22
1
1986;218:1-60.
2
7.
3
and treatment. Eur Spine J. 2005;14(5):427-39.
4
8.
5
experience of 32 cases. Eur Spine J. 2010;19(9):1569-75.
6
9.
7
(Phila Pa 1976). 1997;22(23):2770-6.
8
10. Neurofibromatosis. Conference statement. National Institutes of Health Consensus Development
9
Conference. Archives of neurology. 1988;45(5):575-8.
Tsirikos AI, Saifuddin A, Noordeen MH. Spinal deformity in neurofibromatosis type-1: diagnosis
Koptan W, ElMiligui Y. Surgical correction of severe dystrophic neurofibromatosis scoliosis: an
Kim HW, Weinstein SL. Spine update. The management of scoliosis in neurofibromatosis. Spine
10
11. Marks M, Petcharaporn M, Betz RR, Clements D, Lenke L, Newton PO. Outcomes of surgical
11
treatment in male versus female adolescent idiopathic scoliosis patients. Spine (Phila Pa 1976).
12
2007;32(5):544-9.
13
12. Price CT, Connolly JF, Carantzas AC, Ilyas I. Comparison of bone grafts for posterior spinal
14
fusion in adolescent idiopathic scoliosis. Spine (Phila Pa 1976). 2003;28(8):793-8.
15
13. Albers HW, Hresko MT, Carlson J, Hall JE. Comparison of single- and dual-rod techniques for
16
posterior spinal instrumentation in the treatment of adolescent idiopathic scoliosis. Spine (Phila Pa
17
1976). 2000;25(15):1944-9.
18
14. Lauerman WC, Bradford DS, Transfeldt EE, Ogilvie JW. Management of pseudarthrosis after
19
arthrodesis of the spine for idiopathic scoliosis. J Bone Joint Surg Am. 1991;73(2):222-36.
20
15. Asher M, Min Lai S, Burton D, Manna B. The reliability and concurrent validity of the scoliosis
21
research society-22 patient questionnaire for idiopathic scoliosis. Spine (Phila Pa 1976).
22
2003;28(1):63-9. 16
Page 16 of 22
1
16. Funasaki H, Winter RB, Lonstein JB, Denis F. Pathophysiology of spinal deformities in
2
neurofibromatosis. An analysis of seventy-one patients who had curves associated with dystrophic
3
changes. J Bone Joint Surg Am. 1994;76(5):692-700.
4
17. Crawford AH. Pitfalls of spinal deformities associated with neurofibromatosis in children. Clin
5
Orthop Relat Res. 1989;(245):29-42.
6
18. Illes T, Halmai V, de Jonge T, Dubousset J. Decreased bone mineral density in
7
neurofibromatosis-1 patients with spinal deformities. Osteoporosis international : a journal established
8
as result of cooperation between the European Foundation for Osteoporosis and the National
9
Osteoporosis Foundation of the USA. 2001;12(10):823-7.
10
19. Shen JX, Qiu GX, Wang YP, Zhao Y, Ye QB, Wu ZK. Surgical treatment of scoliosis caused by
11
neurofibromatosis type 1. Chin Med Sci J. 2005;20(2):88-92.
12
20. Vitale MG, Guha A, Skaggs DL. Orthopaedic manifestations of neurofibromatosis in children: an
13
update. Clin Orthop Relat Res. 2002;(401):107-18.
14
21. Crawford AH, Parikh S, Schorry EK, Von Stein D. The immature spine in type-1
15
neurofibromatosis. J Bone Joint Surg Am. 2007;89 Suppl 1:123-42.
16
22. Li M, Fang X, Li Y, Ni J, Gu S, Zhu X. Successful use of posterior instrumented spinal fusion
17
alone for scoliosis in 19 patients with neurofibromatosis type-1 followed up for at least 25 months.
18
Arch Orthop Trauma Surg. 2009;129(7):915-21.
19
23. Barr SJ, Schuette AM, Emans JB. Lumbar pedicle screws versus hooks. Results in double major
20
curves in adolescent idiopathic scoliosis. Spine (Phila Pa 1976). 1997;22(12):1369-79.
21
24. Dobbs MB, Lenke LG, Kim YJ, Kamath G, Peelle MW, Bridwell KH. Selective posterior thoracic
22
fusions for adolescent idiopathic scoliosis: comparison of hooks versus pedicle screws. Spine (Phila Pa 17
Page 17 of 22
1
1976). 2006;31(20):2400-4.
2
25. Cheng I, Kim Y, Gupta MC, et al. Apical sublaminar wires versus pedicle screws--which provides
3
better results for surgical correction of adolescent idiopathic scoliosis? Spine (Phila Pa 1976).
4
2005;30(18):2104-12.
5
26. Wang F, Xu XM, Lu Y, Wei XZ, Zhu XD, Li M. Comparative Analysis of Interval, Skipped, and
6
Key-vertebral Pedicle Screw Strategies for Correction in Patients With Lenke Type 1 Adolescent
7
Idiopathic Scoliosis. Medicine (Baltimore). 2016;95(10):e3021.
8
27. Smith PL, Donaldson S, Hedden D, et al. Parents' and patients' perceptions of postoperative
9
appearance in adolescent idiopathic scoliosis. Spine (Phila Pa 1976). 2006;31(20):2367-74.
10
28. Richards BS, Scaduto A, Vanderhave K, Browne R. Assessment of trunk balance in thoracic
11
scoliosis. Spine (Phila Pa 1976). 2005;30(14):1621-6.
12
29. King HA, Moe JH, Bradford DS, Winter RB. The selection of fusion levels in thoracic idiopathic
13
scoliosis. J Bone Joint Surg Am. 1983;65(9):1302-13.
14
30. Lenke LG, Betz RR, Harms J, et al. Adolescent idiopathic scoliosis: a new classification to
15
determine extent of spinal arthrodesis. J Bone Joint Surg Am. 2001;83-a(8):1169-81.
16
31. Parisini P, Di Silvestre M, Greggi T, Paderni S, Cervellati S, Savini R. Surgical correction of
17
dystrophic spinal curves in neurofibromatosis. A review of 56 patients. Spine (Phila Pa 1976).
18
1999;24(21):2247-53.
19
32. Ton J, Stein-Wexler R, Yen P, Gupta M. Rib head protrusion into the central canal in type 1
20
neurofibromatosis. Pediatric radiology. 2010;40(12):1902-9.
21
33. Gkiokas A, Hadzimichalis S, Vasiliadis E, Katsalouli M, Kannas G. Painful rib hump: a new
22
clinical sign for detecting intraspinal rib displacement in scoliosis due to neurofibromatosis. Scoliosis. 18
Page 18 of 22
1
2006;1:10.
2 3
Figure Legends
4
Fig.1 The 3D-CT scan shows a thin pedicle (red arrow points) found in a NF-1 patient (A); The MRI
5
shows dural ectasia (red arrow points) of a NF-1 patient on the axial (B) and sagittal plane (C).
6 7
Fig.2 The preoperative (A), postoperative (B) and last follow-up (C) posterior-anterior radiographs of a
8
non-dystrophic scoliosis patient with NF-1 and the preoperative (D), postoperative (E) and last
9
follow-up (F) posterior-anterior radiographs of an AIS patient
10
NF-1, neurofibromatosis type-1; AIS, adolescent idiopathic scoliosis.
11 12
Fig.3 The preoperative (A), postoperative (B) and last follow-up (C) lateral radiographs of a
13
non-dystrophic scoliosis patient with NF-1 and the preoperative (D), postoperative (E) and last
14
follow-up (F) lateral radiographs of an AIS patient.
15
NF-1, neurofibromatosis type-1; AIS, adolescent idiopathic scoliosis.
16 17
Fig.4 The preoperative (A, B) and postoperative (C, D) photographs of a non-dystrophic scoliosis
18
patient with NF-1 and the preoperative (E, F) and postoperative (G, H) photographs of an AIS patient.
19
NF-1, neurofibromatosis type-1; AIS, adolescent idiopathic scoliosis.
20
19
Page 19 of 22
1
Table 1 Basic data on the patients NF-1 group
AIS group
P
10 males and 5 females
9 males and 6 females
1.000
10 thoracic scoliosis
10 thoracic scoliosis
3 thoracolumbar scoliosis
3 thoracolumbar scoliosis
2 lumbar scoliosis
2 lumbar scoliosis
Age(year)
13.4±2.0
14.0±2.1
0.386
Risser grade
2.2±2.0
2.3±1.7
0.881
Follow-up time(month)
37.6±3.9
33.5±5.0
0.019
Op. time(min)
242.3±39.5
230.7±37.3
0.412
Blood loss(cc)
796.7±259.4
776.7±248.5
0.950
EV
0
7
EV+1
7
8
EV+2
4
0
EV+3
4
0
Posterior fusion length
10.5±2.9
9.8±2.0
0.464
Screw number
11.6±2.7
10.9±2.0
0.444
Length of stay(d)
15.5±3.9
14.2±3.6
0.364
Sex Main curve
1.000
Fusion strategy
2 3 4 5
0.000
NF-1, neurofibromatosis type-1; AIS, adolescent idiopathic scoliosis; Op., operation; EV, end vertebra.
20
Page 20 of 22
1
Table 2 Radiographic data of patients NF-1 group
AIS group
P
Pre-op Cobb angle (°)
57.3±11.4
58.5±6.4
0.725
Flexibility (%)
36.5±12.5
47.1±14.3
0.038
Postop Cobb angle (°)
11.8±6.2
11.3±5.4
0.803
Correction rate (%)
79.8±10.7
81.1±8.0
0.706
Last follow-up Cobb angle (°)
14.6±7.2
13.8±6.7
0.755
Final correction (%)
74.9±13.6
76.8±10.6
0.775
Loss of correction (°)
2.8±2.2
2.5±2.9
0.567
Loss of correction rate (%)
4.9±4.5
4.3±4.9
0.595
Pre-op Cobb angle (°)
36.7±7.4
33.6±6.8
0.236
Postop Cobb angle (°)
16.9±3.9
16.3±2.7
0.586
Last follow-up Cobb angle (°)
18.1±4.6
17.3±3.0
0.612
17.0±12.1
14.5±11.6
0.436
11.3±4.9
10.5±5.9
0.690
Pre-op SVA (mm)
26.5±18.4
28.9±19.6
0.595
Last follow-up SVA (mm)
16.8±12.0
19.1±12.1
0.512
Coronal plane
Sagittal plane
Balance Pre-op distance between C7PL and CSVL(mm) Last follow-up distance between C7PL and CSVL(mm)
2 21
Page 21 of 22
1 2
NF-1, neurofibromatosis type-1; AIS, adolescent idiopathic scoliosis; C7PL, C7 plumb line; CSVL, center sacral vertical line. SVA, sagittal vertebral axis.
3 4 Table 3 Information of patients who underwent different correction strategies in NF-1 EV+1 group
EV+2 or 3 group
7
8
Initial correction rate (%)
77.9±11.1
80.9±11.3
0.615
Final correction rate (%)
72.0±15.5
77.5±12.1
0.779
Loss of correction (°)
3.1±2.5
2.1±2.1
0.411
Loss of correction rate (%)
5.9±5.6
3.4±3.5
0.397
Op. time(min)
230.7±26.2
252±47.7
0.303
Blood loss(cc)
714.3±195.2
868.8±298.7
0.265
Posterior fusion length
8.7±2.4
12.0±2.4
0.022
Screw number
9.9±2.0
13.1±2.2
0.011
Number of patients
P
Coronal Cobb angle
5 6 7
NF-1, neurofibromatosis type-1; EV, end vertebra; Op., Operation.
8
22
Page 22 of 22
S1529-9430(17)30279-6 http://dx.doi.org/doi: 10.1016/j.spinee.2017.06.011 SPINEE 57351
To appear in:
The Spine Journal
Received date: Revised date: Accepted date:
6-3-2017 2-5-2017 16-6-2017
Please cite this article as: Qiunan Lyu, Chunguang Zhou, Yueming Song, Limin Liu, Lei Wang, Zhongjie Zhou, Does spinal deformity correction of non-dystrophic scoliosis in neurofibromatosis type-1 with one-stage posterior pedicle screw technique produce outcomes similar to adolescent idiopathic scoliosis?, The Spine Journal (2017), http://dx.doi.org/doi: 10.1016/j.spinee.2017.06.011. This is a PDF file of an unedited manuscript that has been accepted for publication. As a service to our customers we are providing this early version of the manuscript. The manuscript will undergo copyediting, typesetting, and review of the resulting proof before it is published in its final form. Please note that during the production process errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain.
1
Title: Does Spinal Deformity Correction of Non-dystrophic Scoliosis in
2
Neurofibromatosis Type-1 with One-stage Posterior Pedicle Screw Technique
3
Produce Outcomes Similar to Adolescent Idiopathic Scoliosis?
4
Authors’ full names: Qiunan Lyu,M.D.; Chunguang Zhou*,PhD; Yueming Song,PhD;
5
Limin Liu,PhD;Lei Wang,PhD; Zhongjie Zhou,PhD;
6
Institution: Department of orthopedics surgery, West China Hospital, Sichuan
7
University, China
8
First Author：Qiunan Lyu
9
Email: [email protected].
10
Corresponding Author: Chunguang Zhou.
11 12 13
E-mail:
;
14
Tel: +86 028 85422430;
15
Fax: +86 028 85423326;
16
Funding Sources/Benefits received: The study was funded by the National Natural
17
Science Foundation of China (Grant No.81401760). No benefits in any form have
18
been or will be received from any commercial party related directly or indirectly to
19
the subject of this article.
20
Device Status: The Manuscript submitted does not contain information about
21
medical device(s)/drug(s).
22 1
Page 1 of 22
1
Abstract
2
Background Context: Efficacy of one-stage posterior pedicle screw instrument used in the treatment
3
of non-dystrophic scoliosis in neurofibromatosis type-1(NF-1) is unknown. And there is no study that
4
has directly compared the results of spinal deformity correction between non-dystrophic scoliosis in
5
NF-1 and adolescent idiopathic scoliosis (AIS).
6
Purpose: To study the efficacy of one-stage posterior pedicle screw instrument used in the treatment of
7
non-dystrophic scoliosis in NF-1 and compare non-dystrophic scoliosis in NF-1 with matched AIS to
8
illustrate the differences.
9
Study Design: Retrospective case control study.
10
Patient Sample: Fifteen patients with non-dystrophic scoliosis in NF-1 and fifteen patients with AIS
11
underwent one-stage posterior surgery with pedicle screw system.
12
Outcome Measures: Preoperative and Postoperative whole-spine radiographs were used to determine
13
coronal and sagittal Cobb angles. And the distance between C7 plumb line (C7PL) and center sacral
14
vertical line (CSVL), sagittal vertebral axis (SVA) were measured to assess spinal balance. Scoliosis
15
Research Society (SRS)-22 questionnaire was used to evaluate functional outcomes.
16
Methods: We matched 15 patients with non-dystrophic scoliosis in NF-1 with AIS patients (ratio, 1:1)
17
for age, sex, and degree of major deformity. Overall mean age was 13.4±2.0 and 14.0±2.1 years,
18
respectively. The NF-1 group consisted of 10 males and 5 females, and the AIS group consisted of 9
19
males and 6 females. Mean follow-up was 37.6±3.9 and 33.5±5.0 months, respectively. The AIS group
20
underwent EV or EV+1 fusion. The NF-1 group underwent EV+1, 2, or 3 fusion. Both coronal and
21
sagittal Cobb angle, trunk balance, operative time, blood loss, fusion levels, length of stay and scores
22
on the Scoliosis Research Society (SRS)-22 questionnaire were compared between two groups. The 2
Page 2 of 22
1
study was supported by the National Natural Science Foundation of China (Grant No.81401760). There
2
were no study-specific conflict of interest–associated biases.
3
Results: The preoperative main curve magnitude was similar between the two groups, however the
4
flexibility of NF-1 group tended to be less than AIS group. The rate of correction of the main curve
5
obtained surgically (79.8% compared with 81.1%) was similar in the NF-1 and AIS groups. There were
6
no significant difference in the loss of correction between two groups(P>0.05).And there were no
7
significant differences between the groups in operative time, blood loss, fusion levels, screw number,
8
length of stay, trunk balance and scores on the SRS-22 . There were no serious complications related to
9
surgery in both groups.
10
Conclusion: Despite the differences in preoperative flexibilities and fusion strategies, non-dystrophic
11
scoliosis in NF-1 can be treated with satisfied correction rate and progression rate similar to
12
comparable AIS by using one-stage posterior pedicle screw technique. Dural ectasia or thin pedicles in
13
non-dystrophic scoliosis could make pedicle screw placement challenging.
14 15
Keywords: spinal deformities; non-dystrophic scoliosis; adolescent idiopathic scoliosis; pedicle screw;
16 17 18 19 20
Introduction
21
Neurofibromatosis (NF) is one of the most common autosomal dominant hereditary disorder
22
which mainly affects cells derived from the neural crest. Usually, NF can be divided into different types, 3
Page 3 of 22
1
and Type 1 (NF-1) also known as von Recklinghausen is the most frequent one. It was reported that
2
about 10%-60% NF-1 patients were complicated by spinal deformities, with scoliosis being the most
3
common skeletal complication. [1, 2]
4
It is a major challenge for spine surgeons to treat spinal deformities in NF-1 with the high
5
incidence of pseudoarthrosis and curve progression. Normally, coronal plane deformity of the thoracic
6
and/or lumbar spine can be divided into non-dystrophic and dystrophic scoliosis based on whether the
7
curve contain 3 or more dystrophic features on the plain radiographs. [3] As the two types of scoliosis
8
in NF-1 differ dramatically both in terms of management and prognosis, a clear distinction between
9
them is extremely important. [4] Although a non-dystrophic scoliosis is regarded less severe than a
10
dystrophic scoliosis and is similar to a normal idiopathic scoliosis, it usually present earlier and
11
progress more easily with a higher pseudarthrosis rate after spinal fusion than an idiopathic one. [5, 6]
12
So far, there are no established practice guidelines for the treatment of non-dystrophic scoliosis
13
associated with NF-1. Different sorts of instruments such as hooks, sublaminar wires and hybrid
14
systems have been applied to correct them ,and occasionally combined anterior-posterior surgeries has
15
been used in some serious cases with these techniques. [7, 8, 9]And non-dystrophic scoliosis treated
16
with these techniques usually progressed more easily and had higher rate of pseudarthrosis after spinal
17
fusion than AIS. [5, 6] However, all these results were obtained from cohort study using hooks,
18
sublaminar wires and hybrid systems.
19
Right now, pedicle screw instrument are widely used to correct scoliosis. In our department, we
20
use posterior pedicle screw instrument to correct both non-dystrophic scoliosis associated with NF-1
21
and AIS. It is observed that patients with non-dystrophic scoliosis who were treated with one-stage
22
posterior pedicle screw instrument haven’t progressed significantly after surgery and the prognosis of 4
Page 4 of 22
1
them has been similar to AIS patients. But there is no study has directly compared the results of
2
surgical treatment between patients with non-dystrophic scoliosis associated with NF-1 and those with
3
AIS. Therefore, the goal of this study was to evaluate the efficacy of one-stage posterior pedicle screw
4
instrument used in the treatment of non-dystrophic scoliosis and compared the results of surgical
5
treatment for non-dystrophic scoliosis patients with matched AIS patients to identify whether the
6
differences in therapeutic efficacy and prognosis still remain.
7
Methods
8
We retrospectively reviewed the records of patients with NF-1 non-dystrophic scoliosis who were
9
treated from 2009 to 2014 at our department. Inclusion criteria for the NF-1 group were as
10
follows:(1)patients who presented with two or more diagnostic criteria of NF-1; [10] (2)patients with
11
scoliosis but did not have dystrophic features; (3)patients who underwent spinal surgery with one-stage
12
posterior segmental pedicle screw technique; (4)patients who had at least 2 years of postoperative
13
follow-up. We also reviewed records of patients with AIS who underwent spinal fusion using the same
14
technique at the database of our department. A one-to-one patient match was carried out based on curve
15
type, magnitude, sex and age to the patients with NF-1. They were required to have a minimum 2-year
16
follow-up. The patients with AIS were selected by a doctor who manage our database and not by
17
authors of the study. Factors not mentioned above were not taken into account in the matching process.
18
Thus, there were 15 patients with NF-1 non-dystrophic scoliosis and 15 patients with AIS included
19
in our study. The NF-1 group consisted of 10 males and 5 females, and the AIS group consisted of 9
20
males and 6 females. Age at surgery was 13.4±2.0 years in NF-1 patients (ranged from 10 to 17 years)
21
and 14.0±2.1 years in AIS patients (ranged from 11 to 18 years). Risser grade at surgery was 2.2±2.0 in
22
NF-1 group and 2.3±1.7 in AIS group. Mean length of follow-up after spinal surgery was 37.6±3.9 5
Page 5 of 22
1
months in NF-1 group and 33.5±5.0months in AIS group. The spinal deformities in NF-1 group
2
included 10 cases of thoracic scoliosis (apical vertebra at T11 or above), three cases of thoracolumbar
3
scoliosis (apical vertebra at T12 or L1) and two cases of lumbar scoliosis(apical vertebra at L2 and
4
below).And curve types in AIS group were the same as those in NF-1 group. There was no significant
5
difference in average age, Risser grade, sex distribution or curve type between both groups (Table 1).
6
All patients underwent clinical examination which includes thorough neurologic evaluation and
7
radiological examination before surgery. Standard standing plain radiographs of the whole spine
8
(posterior-anterior and lateral positions) were used to measure coronal and sagittal curves by the Cobb
9
method. And the distance between C7 plumb line (C7PL) and center sacral vertical line (CSVL),
10
sagittal vertebral axis (SVA) were measured to assess spinal balance. Side-bending radiographs of
11
whole spine were used to evaluate spinal coronal flexibility. The flexibility of the coronal curves was
12
calculated by subtracting the magnitude of the preoperative bending Cobb angle from the magnitude of
13
the preoperative upright coronal Cobb angle and then dividing by the preoperative coronal Cobb angle.
14
[11] Three-dimensional computed tomography (3D-CT) was used to evaluate severity of pedicle
15
deformity for some NF-1 patients preoperatively. It was regarded as an indicator of nonunion or
16
pseudoarthrosis that loss of correction is 10°or more. [12, 13, 14] Magnetic resonance imaging (MRI)
17
of whole spine was used to assess spinal cord condition in all NF-1 patients and some AIS patients
18
before surgery. The following time were analyzed: preoperative, immediate postoperative and latest
19
follow-up.
20
The Scoliosis Research Society (SRS)-22 scores which contains five domains (including pain,
21
general self-image, function/activity, satisfaction and mental health) were used to evaluate the
22
functional outcomes. Each domain has a score ranging from 1 to 5 and 5 is the most favorable. [15] 6
Page 6 of 22
1
All surgeries in both groups were performed by two senior surgeons in our department with
2
somatosensory and motor evoked potential monitoring (SSEP and MEP). Posterior correction and
3
fusion with segmental pedicle screw instrumentation was performed for all patients in two groups.
4
Patients were placed in the prone position on operating table and a posterior median incision was made.
5
In AIS group, 7 patients underwent fusion from upper end vertebra to lower end vertebra (EV) and 8
6
patients underwent fusion from one level proximal to the upper end vertebra to one level distal to the
7
lower end vertebra (EV+1). In NF-1 group, 7 Patients underwent fusion from one level proximal to the
8
upper end vertebra to one level distal to the lower end vertebra (EV+1), 4 Patients underwent fusion
9
from two level proximal to the upper end vertebra to two level distal to the lower end vertebra (EV+2),
10
and 4 Patients underwent fusion from three level proximal to the upper end vertebra to three level distal
11
to the lower end vertebra (EV+3). For some NF-1 patients, pedicles expected to receive screw insertion
12
were evaluated carefully in 3D-CT before surgery and screw insertion in surgical segment was assisted
13
by three-dimension navigation device during surgery. Facetectomies were performed in some serious
14
patients and gradual correction was done with a combination of translation/derotation maneuvers.
15
Thoroughly decortication was performed and the residual autogenous bone was used for posterior and
16
lateral fusions. Allogeneic grafts was used for patients who had not enough residual bone.
17
Postoperatively, all patients were braced for an average of 3 months, and then gradually weaned off the
18
brace.
19
All data were analyzed by using SPSS software (version 22.0; IBM Corp., Armonk, NY, USA).
20
All values are presented as mean ± standard deviation. The Quantitative data were analyzed by using
21
Student’s t test and Man-Whitney U test depending on whether they followed a normal distribution.
22
Categorical data were analyzed by using the χ2 test or Fisher’s exact test. 7
Page 7 of 22
1
Results
2
The operative notes and the radiological results of surgery were evaluated including complications
3
related to the surgical procedure. The mean intraoperative blood loss was 796.7±259.4 ml in NF-1
4
group and 776.7±248.5 ml in AIS group (P>0.05).The average length of stay was 15.5±3.9 days in
5
NF-1 group and 14.2±3.6 days in AIS group (P>0.05).The mean operation time was 242.3±39.5
6
minutes in NF-1 group and 230.7±37.3 minutes in AIS group (P>0.05).
7
In the NF-1 group, dural ectasia was identified in 1 patient and thin pedicles were identified in 8
8
patients on the preoperative MRIs and 3D-CT scans (Fig. 1). Patients in NF-1 group had 10.5±2.9
9
levels instrumented on average, whereas patients in AIS group had 9.8±2.0 levels instrumented on
10
average (P>0.05).The number of inserted screws was 11.6±2.7 on average in NF-1 group and 10.9±2.0
11
on average in AIS group (P>0.05).Table 1 lists the patient operative notes.
12
Patients in both groups had nearly identical preoperative mean major curve cobb angle in coronal
13
plane which was 57.3±11.4°in NF-1 group and 58.5±6.4°in AIS group (P>0.05). The flexibility of
14
NF-1 group tended to be less than AIS group, which was 36.5±12.5 % and 47.1±14.3 % respectively
15
(P<0.05). The mean Cobb angle in coronal plane of scoliosis was reduced to 11.8±6.2°in NF-1 group
16
and 11.3±5.4°in AIS group immediately after surgery (P>0.05). Thus, mean initial curve correction was
17
79.8±10.7% in NF-1 group and 81.1±8.0% in AIS group (P>0.05). At latest follow-up, the mean Cobb
18
angle of scoliosis was 14.6±7.2°in NF-1 group and 13.8±6.7°in AIS group, which indicated the mean
19
correction rate dropped to 74.9±13.6% in NF-1 group and 76.8±10.6% respectively(P>0.05). Fig. 2
20
depicts the preoperative, postoperative and last follow-up posterior-anterior radiographs of a
21
non-dystrophic scoliosis patient with NF-1 and an AIS patient.
22
The mean preoperative sagittal plane deformity was 36.7±7.4°in NF-1 group and 33.6±6.8°in AIS 8
Page 8 of 22
1
group (P>0.05).The mean Cobb angle in sagittal plane was reduced to 16.9±3.9°in NF-1 group and
2
16.3±2.7°in AIS group immediately after surgery (P>0.05).At last follow-up, the mean Cobb angle of
3
kyphosis rose to 18.1±4.6°in NF-1 group and 17.3±3.0°in AIS group (P>0.05).There was no patient
4
who had sagittal Cobb angle exceeding 40°at the last follow-up in both group. Fig. 3 depicts the
5
preoperative, postoperative and last follow-up lateral radiographs of a non-dystrophic scoliosis patient
6
with NF-1 and an AIS patient.
7
The average preoperative distance between C7PL and CSVL was 17.0±12.1 mm in NF-1 group
8
and 14.5±11.6 mm in AIS group (P>0.05).And it improved to 11.3±4.9mm in NF-1 group and 10.5±5.9
9
mm in AIS group at the last follow up (P>0.05).The average preoperative SVA was 26.5±18.4 mm in
10
NF-1 group and 28.9±19.6 mm in AIS group (P>0.05).And it reduced to 16.8±12.0 mm in NF-1 group
11
and 19.1±12.1 mm in AIS group at the last follow up (P>0.05).Table 2 lists radiological results of
12
surgery in both group. Fig. 4 depicts the preoperative and postoperative photographs of a
13
non-dystrophic scoliosis patient with NF-1 and an AIS patient.
14
There were 7 patients in NF-1 group who underwent fusion from one level proximal to the upper
15
end vertebra to one level distal to the lower end vertebra (EV+1) and 8 patients from two or three levels
16
proximal to the upper end vertebra to two or three levels distal to the lower end vertebra (EV+2 or
17
3).The correction rate of coronal cobb angle was 77.9±11.1% in EV+1 group and 80.9±11.3% in EV+2
18
or 3 group immediately after surgery(P>0.05). And it dropped to 72.0±15.5% in EV+1 group and
19
77.5±12.1% in EV+2 or 3 group at the latest follow-up(P>0.05). The mean intraoperative blood loss
20
was 714.3±195.2 ml in EV+1 group and 868.8±298.7 ml in EV+2 or 3 group (P>0.05). The mean
21
operation time was 230.7±26.2 minutes in EV+1 group and 252±47.7 minutes in EV+2 or 3 group
22
(P>0.05). Whereas posterior fusion length and screw number in EV+2 or 3 group were significantly 9
Page 9 of 22
1
higher than those in EV+1 group (P<0.05). Table 3 lists information of patients who underwent
2
different correction strategies in NF-1 group.
3
All patients in both groups completed the SRS-22 functional outcomes instrument preoperatively
4
and postoperatively. There was no significant difference in scores between the two groups before
5
surgery. At the latest follow-up, the non-dystrophic and AIS groups had similar scores in the pain (4.4
6
compared with 4.5), self-image (4.5 compared with 4.5), function (4.7 compared with 4.6) and mental
7
health (4.6 compared with 4.7) domains (P>0.05). And both groups showed improvement in each
8
domain. The two groups also had similar scores in the postoperative domain of satisfaction (4.8
9
compared with 4.7) (P>0.05).
10
No patient had lost curve correction more than 10°or experienced persistent pain or tenderness
11
along the fusion areas in both group. There was no pseudoarthosis or nonunion at the latest follow-up.
12
No additional revision surgeries were performed in both groups at the latest follow-up, whereas
13
whether revision surgery will be performed in the future depends on the continued follow-up results.
14
No patient had a deep wound infection that required revision surgery. One patient in NF-1 group
15
experienced a transient weakness in the left lower limb which fully recovered after administration of
16
methylprednisolone and neurotrophic medicine. There was no intraoperative cerebrospinal fluid leak in
17
both groups. No instrumentation complications were found in both groups, such as broken screws,
18
broken rods and screw dislodgement.
19
Discussion
20
So far, there are few peer-reviewed articles which have presented detailed radiographic outcomes
21
of treatment of spinal deformity in patients with non-dystrophic scoliosis. Although few researches
22
have reported differences in therapeutic efficacy and prognosis between idiopathic and non-dystrophic 10
Page 10 of 22
1
curves, to our certain knowledge, there is no study that has directly compared the results of spinal
2
deformity correction between these two kinds of patients. Before the match, we planned to make
3
flexibility as one of the matching factors. However, in the matching process, it was found that the
4
flexibilities of non-dystrophic scoliosis tended to be less than AIS. As a result, it couldn’t be done to
5
match AIS patients with similar flexibilities. So an age, sex, curve type and magnitude matched
6
comparison between AIS and non-dystrophic scoliosis was performed by us.
7
It has been assumed that the progression and high pseudarthrosis rate of a non-dystrophic curve
8
can be attributed to its natural course. There was an author who concluded four patterns for the natural
9
history of a spinal deformity in patients with NF-1. [16] Crawford [6, 17] indicated that a
10
non-dystrophic curve was possible to transform into a dystrophic one in natural process. Abubakar et al
11
[3] also observed that some non-dystrophic curves were able to transform into dystrophic ones by
12
acquiring various dystrophic morphologic features and defined it as modulation. In their study, 81% of
13
the spinal deformities that developed before 7 years of age showed evidence of modulation. Besides,
14
they believed if a non-dystrophic curve acquired three or more dystrophic features, it was likely to
15
progress afterwards.
16
There have been authors who believe that the progression and failure of fusion in a non-dystrophic
17
scoliosis is related to difficulties in instrumentation. It was reported that stable and strong
18
instrumentation couldn’t be achieved easily with the poor and osteoporotic bone stock in NF-1 patients.
19
[18] And particular changes like vertebral scalloping and thin pedicle which were caused by dural
20
extasia usually made pedicle screw placement challenging and weakened the fixation of posterior
21
instrumentation (Fig. 1). Furthermore, some studies suggested that spinal deformities in NF-1
22
sometime progressed even if the arthodesis was completed. [19, 20] To sum up, scoliosis in NF-1 has 11
Page 11 of 22
1
been difficult to treat as failure of fixation and loss of correction have been frequent occurrence.
2
However, these conclusions were mainly concluded from some outdated techniques.
3
In previous studies, non-dystrophic scoliosis in NF-1 was usually treated with the Harrington or
4
Luque technique which has inadequate fixation strength. The rate of internal fixation failure and curve
5
correction loss were high. Thus, it was suggested that serious non-dystrophic scoliosis should be treated
6
with combined anterior release and bone grafting followed by posterior spine fusion with the use of
7
instrumentation. [7, 21] In the past decade, posterior hook-rod-based instrumentation has been used in
8
the treatment of non-dystrophic scoliosis. [1, 19, 22] And the post-operative coronal correction has
9
ranged from 61.3% to 69.2%, which has suggested that posterior fusion alone can be used in treating
10
serious non-dystrophic curves and gain an acceptable outcome. However, this instrumentation still has
11
many limitations compared with pedicle screw. It was reported that pedicle screw fixation demonstrates
12
better corrective ability compared to traditional hook/hybrid instrumentation in the treatment of AIS
13
patients. [23, 24] Besides, pedicle screw instrumentation could reduce blood loss, make anterior
14
surgery unnecessary and cut down total cost. [25] Thus, it is of great value to study the efficacy of
15
pedicle screw instrumentation in the treatment of NF-1 non-dystrophic scoliosis.
16
In our study, spinal deformity correction in NF-1 group was similar to AIS group. The results
17
reported here showed that curve correction in AIS group was similar to those been reported before. [26]
18
And curve correction in our NF-1 group was better than other non-dystrophic scoliosis patients treated
19
by hook-rod-based instrumentation. [1, 19, 22] The study also showed that there were no apparent
20
progression of deformity with the pedicle screw system at the latest follow-up in both groups. And the
21
mean correction loss rate was similar between the two groups. Besides, there was no significant
22
difference in the average length of stay, blood loss and operative time between both groups. Therefore, 12
Page 12 of 22
1
the results suggested that posterior pedicle screw fixation and fusion alone could yield same
2
satisfactory outcomes in both AIS and non-dystrophic scoliosis.
3
As for trunk balance, mean distance between C7PL and CSVL and mean SVA were both
4
satisfactory at the latest follow-up in NF-1 group and AIS group, and there was no patient get trunk
5
imbalance. Many previous articles studied the principles of retaining trunk balance and the concepts of
6
aesthetics AIS patients. [27, 28] Although patients with scoliosis in NF-1 have not been studied in this
7
area, it is also important to regain or maintain total trunk balance for them as there are many
8
similarities between AIS and NF-1 scoliosis.
9
The SRS-22 questionnaire has been applied to evaluating changes in patients with scoliosis who
10
undergo a surgery. [15] In our study, five domains of SRS-22 including pain, general function,
11
self-image and mental health scores were similar between the two groups, which suggests that patients
12
with non-dystrophic scoliosis and those with AIS can obtain parallel clinical outcomes with posterior
13
pedicle screw fixation and fusion.
14
At present, there have been many articles about selection of fusion and instrumentation levels in
15
AIS, however fusion strategy for scoliosis in NF-1 has not been widely discussed. [29, 30] There is no
16
accepted classification system or standard surgical decision-making plan for non-dystrophic scoliosis in
17
NF-1.So the selection of fusion and instrumentation levels for non-dystrophic scoliosis is more difficult
18
than AIS. In our study, patients in AIS group underwent EV or EV+1 fusion. And patients in NF-1
19
group underwent EV+1, 2 or 3 fusion in order to achieve satisfactory correction and prevent curve
20
progression after surgery. There was no decompensation or adding-on in the NF-1 group. And our
21
results showed that correction rate and correction loss rate had no difference in EV+1 group and EV+2
22
or 3 group in NF-1 patients. It suggests that EV+1 fusion strategy is enough for non-dystrophic 13
Page 13 of 22
1
scoliosis in NF-1.However, as it is widely accepted that fewer segments should be fused to preserve
2
more lumbar mobility and prevent early degeneration of distal intervertebral disc, fusion strategies
3
which could preserve one or two more mobile segments than EV+1 fusion should be taken in to
4
consideration in the future studies.
5
Although the fusion strategy of AIS group could preserve more segments than the one of
6
non-dystrophic scoliosis group, patients in both groups had almost identical average posterior fusion
7
length and screw number. After reviewing the radiographs of NF-1 patients, we found that curves in
8
non-dystrophic patients tend to be sharply angulated curvature and contain less segments. In other
9
words, curves of AIS usually involve more segments than curves of non-dystrophic scoliosis if their
10
magnitudes are similar. As a result, in spite of different fusion strategies in both groups, the average
11
posterior fusion length and screw number were alike in two groups as curve magnitudes of both groups
12
had no significant differences.
13
It has been widely believed that complications after surgery in NF-1 patients are much common
14
and serious than those in AIS patients. Previous studies suggested that the incidence of pseudoarthrosis
15
after spinal fusion in NF-1 patients with dystrophic or non-dystrophic spinal deformities was higher
16
than in patients with AIS, and the incidence ranged from 15% to 47%. [5, 31] And a neurologic deficit
17
in patients with NF-1 was easier to be encountered than in patients with AIS, as NF-1 scoliosis patients
18
tended to present spinal cord compression secondary to spinal deformity, rib penetration into the spinal
19
canal and intraspinal tumors. [32, 33] However, our study showed there was no fusion failure in both
20
group and main complications had no significant difference between two groups.
21
Conclusions
22
In conclusion, despite the differences in preoperative flexibilities and fusion strategies, 14
Page 14 of 22
1
non-dystrophic scoliosis in NF-1 can be treated with satisfied clinical and radiographic outcomes
2
similar to comparable AIS by using one-stage posterior pedicle screw technique. Dural ectasia or thin
3
pedicles in non-dystrophic scoliosis could make pedicle screw placement challenging. We hoped that
4
this improved awareness could help improve the safety and efficacy of surgical management for
5
patients with non-dystrophic scoliosis. However, the number of patients was small and the preoperative
6
flexibilities and fusion strategies of the two groups were different in the study. So, further large-scale
7
and well-designed studies are needed to draw a more convincing conclusion and optimize the surgical
8
management for non-dystrophic scoliosis.
9 10
References
11
1.
12
neurofibromatosis type 1. Report of 12 cases. J Neurosurg. 2002;97(3 Suppl):310-6.
13
2.
14
Spine (Phila Pa 1976). 1992;17(8 Suppl):S244-8.
15
3.
16
deformities in patients with neurofibromatosis type 1. Spine (Phila Pa 1976). 2000;25(1):69-75.
17
4.
18
dystrophic features in patients with type 1 neurofibromatosis and spinal deformities increase the risk of
19
surgery? Spine (Phila Pa 1976). 2013;38(18):1595-601.
20
5.
21
Orthop Relat Res. 1989;(245):24-8.
22
6.
Halmai V, Doman I, de Jonge T, Illes T. Surgical treatment of spinal deformities associated with
Akbarnia BA, Gabriel KR, Beckman E, Chalk D. Prevalence of scoliosis in neurofibromatosis.
Durrani AA, Crawford AH, Chouhdry SN, Saifuddin A, Morley TR. Modulation of spinal
Lykissas MG, Schorry EK, Crawford AH, Gaines S, Rieley M, Jain VV. Does the presence of
Shufflebarger HL. Cotrel-Dubousset instrumentation in neurofibromatosis spinal problems. Clin
Crawford AH. Neurofibromatosis in children. Acta orthopaedica Scandinavica Supplementum. 15
Page 15 of 22
1
1986;218:1-60.
2
7.
3
and treatment. Eur Spine J. 2005;14(5):427-39.
4
8.
5
experience of 32 cases. Eur Spine J. 2010;19(9):1569-75.
6
9.
7
(Phila Pa 1976). 1997;22(23):2770-6.
8
10. Neurofibromatosis. Conference statement. National Institutes of Health Consensus Development
9
Conference. Archives of neurology. 1988;45(5):575-8.
Tsirikos AI, Saifuddin A, Noordeen MH. Spinal deformity in neurofibromatosis type-1: diagnosis
Koptan W, ElMiligui Y. Surgical correction of severe dystrophic neurofibromatosis scoliosis: an
Kim HW, Weinstein SL. Spine update. The management of scoliosis in neurofibromatosis. Spine
10
11. Marks M, Petcharaporn M, Betz RR, Clements D, Lenke L, Newton PO. Outcomes of surgical
11
treatment in male versus female adolescent idiopathic scoliosis patients. Spine (Phila Pa 1976).
12
2007;32(5):544-9.
13
12. Price CT, Connolly JF, Carantzas AC, Ilyas I. Comparison of bone grafts for posterior spinal
14
fusion in adolescent idiopathic scoliosis. Spine (Phila Pa 1976). 2003;28(8):793-8.
15
13. Albers HW, Hresko MT, Carlson J, Hall JE. Comparison of single- and dual-rod techniques for
16
posterior spinal instrumentation in the treatment of adolescent idiopathic scoliosis. Spine (Phila Pa
17
1976). 2000;25(15):1944-9.
18
14. Lauerman WC, Bradford DS, Transfeldt EE, Ogilvie JW. Management of pseudarthrosis after
19
arthrodesis of the spine for idiopathic scoliosis. J Bone Joint Surg Am. 1991;73(2):222-36.
20
15. Asher M, Min Lai S, Burton D, Manna B. The reliability and concurrent validity of the scoliosis
21
research society-22 patient questionnaire for idiopathic scoliosis. Spine (Phila Pa 1976).
22
2003;28(1):63-9. 16
Page 16 of 22
1
16. Funasaki H, Winter RB, Lonstein JB, Denis F. Pathophysiology of spinal deformities in
2
neurofibromatosis. An analysis of seventy-one patients who had curves associated with dystrophic
3
changes. J Bone Joint Surg Am. 1994;76(5):692-700.
4
17. Crawford AH. Pitfalls of spinal deformities associated with neurofibromatosis in children. Clin
5
Orthop Relat Res. 1989;(245):29-42.
6
18. Illes T, Halmai V, de Jonge T, Dubousset J. Decreased bone mineral density in
7
neurofibromatosis-1 patients with spinal deformities. Osteoporosis international : a journal established
8
as result of cooperation between the European Foundation for Osteoporosis and the National
9
Osteoporosis Foundation of the USA. 2001;12(10):823-7.
10
19. Shen JX, Qiu GX, Wang YP, Zhao Y, Ye QB, Wu ZK. Surgical treatment of scoliosis caused by
11
neurofibromatosis type 1. Chin Med Sci J. 2005;20(2):88-92.
12
20. Vitale MG, Guha A, Skaggs DL. Orthopaedic manifestations of neurofibromatosis in children: an
13
update. Clin Orthop Relat Res. 2002;(401):107-18.
14
21. Crawford AH, Parikh S, Schorry EK, Von Stein D. The immature spine in type-1
15
neurofibromatosis. J Bone Joint Surg Am. 2007;89 Suppl 1:123-42.
16
22. Li M, Fang X, Li Y, Ni J, Gu S, Zhu X. Successful use of posterior instrumented spinal fusion
17
alone for scoliosis in 19 patients with neurofibromatosis type-1 followed up for at least 25 months.
18
Arch Orthop Trauma Surg. 2009;129(7):915-21.
19
23. Barr SJ, Schuette AM, Emans JB. Lumbar pedicle screws versus hooks. Results in double major
20
curves in adolescent idiopathic scoliosis. Spine (Phila Pa 1976). 1997;22(12):1369-79.
21
24. Dobbs MB, Lenke LG, Kim YJ, Kamath G, Peelle MW, Bridwell KH. Selective posterior thoracic
22
fusions for adolescent idiopathic scoliosis: comparison of hooks versus pedicle screws. Spine (Phila Pa 17
Page 17 of 22
1
1976). 2006;31(20):2400-4.
2
25. Cheng I, Kim Y, Gupta MC, et al. Apical sublaminar wires versus pedicle screws--which provides
3
better results for surgical correction of adolescent idiopathic scoliosis? Spine (Phila Pa 1976).
4
2005;30(18):2104-12.
5
26. Wang F, Xu XM, Lu Y, Wei XZ, Zhu XD, Li M. Comparative Analysis of Interval, Skipped, and
6
Key-vertebral Pedicle Screw Strategies for Correction in Patients With Lenke Type 1 Adolescent
7
Idiopathic Scoliosis. Medicine (Baltimore). 2016;95(10):e3021.
8
27. Smith PL, Donaldson S, Hedden D, et al. Parents' and patients' perceptions of postoperative
9
appearance in adolescent idiopathic scoliosis. Spine (Phila Pa 1976). 2006;31(20):2367-74.
10
28. Richards BS, Scaduto A, Vanderhave K, Browne R. Assessment of trunk balance in thoracic
11
scoliosis. Spine (Phila Pa 1976). 2005;30(14):1621-6.
12
29. King HA, Moe JH, Bradford DS, Winter RB. The selection of fusion levels in thoracic idiopathic
13
scoliosis. J Bone Joint Surg Am. 1983;65(9):1302-13.
14
30. Lenke LG, Betz RR, Harms J, et al. Adolescent idiopathic scoliosis: a new classification to
15
determine extent of spinal arthrodesis. J Bone Joint Surg Am. 2001;83-a(8):1169-81.
16
31. Parisini P, Di Silvestre M, Greggi T, Paderni S, Cervellati S, Savini R. Surgical correction of
17
dystrophic spinal curves in neurofibromatosis. A review of 56 patients. Spine (Phila Pa 1976).
18
1999;24(21):2247-53.
19
32. Ton J, Stein-Wexler R, Yen P, Gupta M. Rib head protrusion into the central canal in type 1
20
neurofibromatosis. Pediatric radiology. 2010;40(12):1902-9.
21
33. Gkiokas A, Hadzimichalis S, Vasiliadis E, Katsalouli M, Kannas G. Painful rib hump: a new
22
clinical sign for detecting intraspinal rib displacement in scoliosis due to neurofibromatosis. Scoliosis. 18
Page 18 of 22
1
2006;1:10.
2 3
Figure Legends
4
Fig.1 The 3D-CT scan shows a thin pedicle (red arrow points) found in a NF-1 patient (A); The MRI
5
shows dural ectasia (red arrow points) of a NF-1 patient on the axial (B) and sagittal plane (C).
6 7
Fig.2 The preoperative (A), postoperative (B) and last follow-up (C) posterior-anterior radiographs of a
8
non-dystrophic scoliosis patient with NF-1 and the preoperative (D), postoperative (E) and last
9
follow-up (F) posterior-anterior radiographs of an AIS patient
10
NF-1, neurofibromatosis type-1; AIS, adolescent idiopathic scoliosis.
11 12
Fig.3 The preoperative (A), postoperative (B) and last follow-up (C) lateral radiographs of a
13
non-dystrophic scoliosis patient with NF-1 and the preoperative (D), postoperative (E) and last
14
follow-up (F) lateral radiographs of an AIS patient.
15
NF-1, neurofibromatosis type-1; AIS, adolescent idiopathic scoliosis.
16 17
Fig.4 The preoperative (A, B) and postoperative (C, D) photographs of a non-dystrophic scoliosis
18
patient with NF-1 and the preoperative (E, F) and postoperative (G, H) photographs of an AIS patient.
19
NF-1, neurofibromatosis type-1; AIS, adolescent idiopathic scoliosis.
20
19
Page 19 of 22
1
Table 1 Basic data on the patients NF-1 group
AIS group
P
10 males and 5 females
9 males and 6 females
1.000
10 thoracic scoliosis
10 thoracic scoliosis
3 thoracolumbar scoliosis
3 thoracolumbar scoliosis
2 lumbar scoliosis
2 lumbar scoliosis
Age(year)
13.4±2.0
14.0±2.1
0.386
Risser grade
2.2±2.0
2.3±1.7
0.881
Follow-up time(month)
37.6±3.9
33.5±5.0
0.019
Op. time(min)
242.3±39.5
230.7±37.3
0.412
Blood loss(cc)
796.7±259.4
776.7±248.5
0.950
EV
0
7
EV+1
7
8
EV+2
4
0
EV+3
4
0
Posterior fusion length
10.5±2.9
9.8±2.0
0.464
Screw number
11.6±2.7
10.9±2.0
0.444
Length of stay(d)
15.5±3.9
14.2±3.6
0.364
Sex Main curve
1.000
Fusion strategy
2 3 4 5
0.000
NF-1, neurofibromatosis type-1; AIS, adolescent idiopathic scoliosis; Op., operation; EV, end vertebra.
20
Page 20 of 22
1
Table 2 Radiographic data of patients NF-1 group
AIS group
P
Pre-op Cobb angle (°)
57.3±11.4
58.5±6.4
0.725
Flexibility (%)
36.5±12.5
47.1±14.3
0.038
Postop Cobb angle (°)
11.8±6.2
11.3±5.4
0.803
Correction rate (%)
79.8±10.7
81.1±8.0
0.706
Last follow-up Cobb angle (°)
14.6±7.2
13.8±6.7
0.755
Final correction (%)
74.9±13.6
76.8±10.6
0.775
Loss of correction (°)
2.8±2.2
2.5±2.9
0.567
Loss of correction rate (%)
4.9±4.5
4.3±4.9
0.595
Pre-op Cobb angle (°)
36.7±7.4
33.6±6.8
0.236
Postop Cobb angle (°)
16.9±3.9
16.3±2.7
0.586
Last follow-up Cobb angle (°)
18.1±4.6
17.3±3.0
0.612
17.0±12.1
14.5±11.6
0.436
11.3±4.9
10.5±5.9
0.690
Pre-op SVA (mm)
26.5±18.4
28.9±19.6
0.595
Last follow-up SVA (mm)
16.8±12.0
19.1±12.1
0.512
Coronal plane
Sagittal plane
Balance Pre-op distance between C7PL and CSVL(mm) Last follow-up distance between C7PL and CSVL(mm)
2 21
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1 2
NF-1, neurofibromatosis type-1; AIS, adolescent idiopathic scoliosis; C7PL, C7 plumb line; CSVL, center sacral vertical line. SVA, sagittal vertebral axis.
3 4 Table 3 Information of patients who underwent different correction strategies in NF-1 EV+1 group
EV+2 or 3 group
7
8
Initial correction rate (%)
77.9±11.1
80.9±11.3
0.615
Final correction rate (%)
72.0±15.5
77.5±12.1
0.779
Loss of correction (°)
3.1±2.5
2.1±2.1
0.411
Loss of correction rate (%)
5.9±5.6
3.4±3.5
0.397
Op. time(min)
230.7±26.2
252±47.7
0.303
Blood loss(cc)
714.3±195.2
868.8±298.7
0.265
Posterior fusion length
8.7±2.4
12.0±2.4
0.022
Screw number
9.9±2.0
13.1±2.2
0.011
Number of patients
P
Coronal Cobb angle
5 6 7
NF-1, neurofibromatosis type-1; EV, end vertebra; Op., Operation.
8
22
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