Showing papers by "Behrooz A. Akbarnia published in 2014"

Development and initial validation of the classification of early-onset scoliosis (C-EOS)

Abstract: Background: Early-onset scoliosis is a heterogeneous condition, with highly variable manifestations and natural history. No standardized classification system exists to describe and group patients, to guide optimal care, or to prognosticate outcomes within this population. A classification system for early-onset scoliosis is thus a necessary prerequisite to the timely evolution of care of these patients. Methods: Fifteen experienced surgeons participated in a nominal group technique designed to achieve a consensus-based classification system for early-onset scoliosis. A comprehensive list of factors important in managing early-onset scoliosis was generated using a standardized literature review, semi-structured interviews, and open forum discussion. Three group meetings and two rounds of surveying guided the selection of classification components, subgroupings, and cut-points. Initial validation of the system was conducted using an interobserver reliability assessment based on the classification of a series of thirty cases. Results: Nominal group technique was used to identify three core variables (major curve angle, etiology, and kyphosis) with high group content validity scores. Age and curve progression ranked slightly lower. Participants evaluated the cases of thirty patients with early-onset scoliosis for reliability testing. The mean kappa value for etiology (0.64) was substantial, while the mean kappa values for major curve angle (0.95) and kyphosis (0.93) indicated almost perfect agreement. The final classification consisted of a continuous age prefix, etiology (congenital or structural, neuromuscular, syndromic, and idiopathic), major curve angle (1, 2, 3, or 4), and kyphosis (–, N, or +) variables, and an optional progression modifier (P0, P1, or P2). Conclusions: Utilizing formal consensus-building methods in a large group of surgeons experienced in treating early-onset scoliosis, a novel classification system for early-onset scoliosis was developed with all core components demonstrating substantial to excellent interobserver reliability. This classification system will serve as a foundation to guide ongoing research efforts and standardize communication in the clinical setting.

A classification of growth friendly spine implants.

Abstract: Background Various types of spinal implants have been used with the objective of minimizing spinal deformities while maximizing the spine and thoracic growth in a growing child with a spinal deformity. Purpose The aim of this study was to describe a classification system of growth friendly spinal implants to allow researchers and clinicians to have a common language and facilitate comparative studies. Growth friendly spinal implant systems fall into 3 categories based upon the forces of correction the implants exert on the spine, which are as follows: Distraction-based systems correct spinal deformities by mechanically applying a distractive force across a deformed segment with anchors at the top and bottom of the implants, which commonly attach to the spine, rib, and/or the pelvis. The present examples of distraction-based implants are spine-based or rib-based growing rods, vertical expandable titanium rib prosthesis, and remotely expandable devices. Compression-based systems correct spinal deformities with a compressive force applied to the convexity of the curve causing convex growth inhibition. This compressive force may be generated both mechanically at the time of implantation, as well as over time resulting from longitudinal growth of vertebral endplates hindered by the spinal implants. Examples of compression-based systems are vertebral staples and tethers. Guided growth systems correct spinal deformity by anchoring multiple vertebrae (usually including the apical vertebrae) to rods with mechanical forces including translation at the time of the initial implant. The majority of the anchors are not rigidly attached to the rods, thus permitting longitudinal growth over time as the anchors slide over the rods. Examples of guided growth systems include the Luque trolley and Shilla. Conclusions Each system has its benefits and shortcomings. Knowledge of the fundamental principles upon which these systems are based may aid the clinician to choose an appropriate treatment for patients. Having a common language for these systems may aid in comparative research. Vertical expandable titanium rib prosthesis is used with humanitarian exemption. The other devices mentioned in this manuscript are not approved for growing constructs by the Food and Drug Administration and are used off-label.

Traditional Growing Rods Versus Magnetically Controlled Growing Rods for the Surgical Treatment of Early-Onset Scoliosis: A Case-Matched 2-Year Study.

Abstract: Introduction Traditional growing rod (TGR) surgery is a treatment technique commonly used for progressive early-onset scoliosis. Studies have shown that repeated TGR lengthenings can significantly increase the risk of complications. Magnetically controlled growing rods (MCGR) are currently available outside of the United States and early results have been promising. The purpose of this study was to compare the effectiveness of MCGR versus TGR for the treatment of early-onset scoliosis. Methods Magnetically controlled growing rod patients were selected based on the following criteria: aged less than 10 years, major curve greater than 30°, thoracic height less than 22 cm, no previous spine surgery, and minimum 2-year follow-up. A total of 17 MCGR patients met the inclusion criteria, 12 of whom had complete data available for analysis. Each MCGR patient was matched with a TGR patient by etiology, gender, single versus dual rods, preoperative age, and preoperative major curve. Results Magnetically controlled growing rod patients had a mean age of 6.8 years and mean follow-up of 2.5 years. Mean follow-up was greater for TGR patients by 1.6 years. Major curve correction was similar between MCGR and TGR patients throughout treatment. The MCGR patients experienced an average of 8.1 mm/year increase in T1–S1 during the lengthening period, compared with 9.7 mm/year for TGR patients (p = .73). There was a mean increase in T1–T12 of 1.5 mm/year for MCGR patients and 2.3 mm/year for TGR patients (p = .83). The TGR patients had 73 open surgeries, 56 of which were lengthenings. The MCGR patients had 16 open surgeries and 137 noninvasive lengthenings. Three TGR patients underwent 5 unplanned revision surgeries whereas 3 MCGR patients underwent 4 unplanned revisions. Conclusions Major curve correction was similar between MCGR and TGR patients throughout treatment. Annual T1–S1 and T1–12 growth was also similar between groups. The MCGR patients had 57 fewer surgical procedures than TGR patients. Incidence of unplanned surgical revisions as a result of complications was similar between groups.

The minimally invasive spinal deformity surgery algorithm: a reproducible rational framework for decision making in minimally invasive spinal deformity surgery.

Abstract: Object Minimally invasive surgery (MIS) is an alternative to open deformity surgery for the treatment of patients with adult spinal deformity. However, at this time MIS techniques are not as versatile as open deformity techniques, and MIS techniques have been reported to result in suboptimal sagittal plane correction or pseudarthrosis when used for severe deformities. The minimally invasive spinal deformity surgery (MISDEF) algorithm was created to provide a framework for rational decision making for surgeons who are considering MIS versus open spine surgery. Methods A team of experienced spinal deformity surgeons developed the MISDEF algorithm that incorporates a patient's preoperative radiographic parameters and leads to one of 3 general plans ranging from MIS direct or indirect decompression to open deformity surgery with osteotomies. The authors surveyed fellowship-trained spine surgeons experienced with spinal deformity surgery to validate the algorithm using a set of 20 cases to establish interobser...

Anterior column realignment (ACR) for focal kyphotic spinal deformity using a lateral transpsoas approach and ALL release.

Abstract: Study Design:Retrospective case series.Objectives:Introduce and evaluate the safety of a new technique of anterior column realignment (ACR) using a lateral transpsoas approach with release of anterior longitudinal ligament and annulus for correction of focal kyphotic deformity.Summary of Background

Deep Surgical Site Infection Following 2344 Growing-Rod Procedures for Early-Onset Scoliosis: Risk Factors and Clinical Consequences.

Abstract: Background: Deep surgical site infection may change the course of growing-rod treatment of early-onset scoliosis. Our goal was to assess the effect of this complication on subsequent treatment. Methods: A multicenter international database was retrospectively reviewed; 379 patients treated with growing-rod surgery and followed for a minimum of two years were identified. Deep surgical site infection was defined as any infection requiring surgical intervention. Results: Forty-two patients (11.1%; twenty-five males and seventeen females) developed at least one deep surgical site infection. The mean age at the initial growing-rod surgery was 6.3 years (range, 0.6 to 13.2 years) and the mean duration of follow-up was 5.3 years (range, 2.2 to 14.3 years). The mean interval between the initial surgery and the first deep surgical site infection was 2.8 years (range, 0.02 to 7.9 years). Ten (2.6%) of the 379 patients developed deep surgical site infection before the first lengthening. Twenty-nine patients (7.7%) developed the infection during the course of the lengthening procedures, and three patients (0.8%) developed it after final fusion surgery. Thirty (13.6%) of 221 patients with stainless-steel implants had at least one deep surgical site infection compared with twelve (8%) of 150 patients with titanium implants (p < 0.05). (The remaining patients were treated with chromium-cobalt implants.) Twenty-two (52.4%) of the forty-two patients with deep surgical site infection underwent implant removal, which was complete in thirteen and partial in nine. Growing-rod treatment was terminated in two patients with partial removal and six patients with complete removal. An increased risk of deep surgical site infection was associated with stainless-steel implants (odds ratio [OR] = 5.7), non-ambulatory status (OR = 2.9), and the number of revisions before the development of deep surgical site infection (OR = 3.3). Neuromuscular etiology and non-ambulatory status increased the possibility of implant removal to treat infection (p < 0.05). Conclusions: The prevalence of deep surgical site infection associated with growing-rod surgery is higher than that associated with standard pediatric spinal fusion (historical data). Non-ambulatory status, more revisions, and stainless-steel implants increased the risk of deep surgical site infection. After eight surgical procedures, the risk of deep surgical site infection increased to approximately 50%. When patients have implant removal, efforts should be made to retain one longitudinal implant to continue treatment. Level of Evidence: Therapeutic Level IV. See Instructions for Authors for a complete description of levels of evidence.

Comparison of radiographic results after minimally invasive, hybrid, and open surgery for adult spinal deformity: a multicenter study of 184 patients

Abstract: .Regarding radiographic outcomes, the MIS group maintained a significantly smaller mean lumbar Cobb angle (13.1°) after surgery compared with the open group (20.4°, p = 0.002), while the hybrid group had a significantly larger lumbar curve correction (26.6°) compared with the MIS group (18.8°, p = 0.045). The mean change in the PI-LL was larger for the hybrid group (20.6°) compared with the open (10.2°, p = 0.023) and MIS groups (5.5°, p = 0.003). The mean sagittal vertical axis correction was greater for the open group (25 mm) compared with the MIS group (≤ 1 mm, p = 0.008). Patients in the open group had a significantly larger postoperative thoracic kyphosis (41.45°) compared with the MIS patients (33.5°, p = 0.005). There were no significant differences between groups in terms of pre- and postoperative mean ODI and VAS scores at the 1-year follow-up. However, patients in the MIS group had much lower estimated blood loss and transfusion rates compared with patients in the hybrid or open groups (p < 0.001). Operating room time was significantly longer with the hybrid group compared with the MIS and open groups (p < 0.001). Major complications occurred in 14% of patients in the MIS group, 14% in the hybrid group, and 45% in the open group (p = 0.032). Conclusions. This study provides valuable baseline characteristics of radiographic parameters among 3 different surgical techniques used in the treatment of adult spinal deformity. Each technique has advantages, but much like any surgical technique, the positive and negative elements must be considered when tailoring a treatment to a patient. Minimally invasive surgical techniques can result in clinical outcomes at 1 year comparable to those obtained from hybrid and open surgical techniques.

The Growing Spine:Management of Spinal Disorders in Young Children

Abstract: The Growing Spine:Management of Spinal Disorders in Young Children , The Growing Spine:Management of Spinal Disorders in Young Children , کتابخانه دیجیتال جندی شاپور اهواز

The effect of serial growing rod lengthening on the sagittal profile and pelvic parameters in early-onset scoliosis.

Abstract: Study design Retrospective case series. Objective To report the effect of repeated growing rod (GR) lengthenings on the sagittal and pelvic profile in patients with early-onset scoliosis. Summary of background data Posterior distraction-based GRs have gained popularity as a technique for the surgical management of early-onset scoliosis. However, there are no published studies on the effect of serial GR lengthenings on sagittal balance, thoracic kyphosis (TK), lumbar lordosis (LL), and pelvic parameters. Methods We retrospectively reviewed data from a multicenter early-onset scoliosis database. Forty-three patients who were able to walk with minimum 2-year follow-up who underwent single- or dual-GR surgery were included for review. Mean number of lengthenings was 6.4 (range, 3-16). Mean preoperative age was 5.6 years (standard deviation, 2.4 yr), and mean follow-up was 3.5 years. Maximum TK, LL, and sagittal balance were assessed preoperatively, after index surgery, and at the latest follow-up. Results There was a significant decrease both in TK and LL after index surgery, which then increased during the lengthening period. There was a significant increase in both proximal junctional kyphosis and distal junctional angle. Pelvic parameters (pelvic tilt, pelvic incidence, sacral slope) were unchanged during the treatment period. Significant improvement was observed in sagittal balance. There was a correlation between the change in TK and change in LL. Conclusion TK decreased after index surgery and increased between the index surgery and the latest follow-up, which was accompanied by an increase in LL. All-screw proximal constructs had mean 9° more proximal junctional kyphosis than all-hook proximal constructs. An increase in proximal junctional kyphosis and distal junctional angle was found during the treatment period. Although there was an independent effect of number of lengthenings on TK, there was no significant detrimental effect on other sagittal spinopelvic parameters. GRs had a positive effect on sagittal vertical axis, which returned patients to a more neutral alignment through the course of treatment. Level of evidence 4.

Does recombinant human bone morphogenetic protein-2 use in adult spinal deformity increase complications and are complications associated with location of rhBMP-2 use? A prospective, multicenter study of 279 consecutive patients.

Abstract: Study Design.Multicenter, prospective analysis of consecutive patients with adult spinal deformity (ASD).Objective.Evaluate complications associated with recombinant human bone morphogenetic protein-2 (rhBMP-2) use in ASD.Summary of Background Data.Off-label rhBMP-2 use is common; however, underrepo

Patients with adult spinal deformity treated operatively report greater baseline pain and disability than patients treated nonoperatively; however, deformities differ between age groups.

Abstract: Study Design. Multicenter, prospective analysis of consecutive patients with adult spinal deformity (ASD). Objective. Identify age-related radiographical parameters associated with poor health-related quality of life (HRQOL) and treatment preferences for ASD. Summary of Background Data. Patients with ASD report discrepant severities of disability. Understanding age-associated differences for reported disability and treatment preferences may improve ASD evaluation and treatment. Methods. Baseline demographic, radiographical, and HRQOL values were evaluated in a multicenter, prospective cohort of consecutive patients with ASD. Inclusion criteria: ASD, age more

Flexible fastening system

Abstract: A flexible implant system includes a flexible implant, an implant housing, and an implant set screw. The flexible implant is configured to loop around a portion of a bony element. The implant housing includes a housing body defining a rod passage configured to receive an rod. The housing body also defines an implant passage that receives a portion of the flexible implant. The implant set screw engages the flexible implant within the implant passage to fix the flexible implant to the implant housing.

Are Rib Versus Spine Anchors Protective Against Breakage of Growing Rods

Abstract: Study Design Retrospective multicenter, case-control study. Objective To compare the risks of rod breakage and anchor complications between distraction-based growing rods with proximal spine versus rib anchors. Summary of Background Data Rod breakage is a known complication of distraction-based growing rod instrumentation. Methods A total of 176 patients met inclusion criteria: minimum 2-year follow-up, younger than age 9 years at index surgery, non–Vertical Expandable Prosthetic Titanium Rib distraction-based growing rods, and known anchor locations. Mean follow-up was 56 months (range, 24–152 months). Survival analyses using Cox proportional hazards model (accounting for varying lengths of follow-up) of rod breakage, anchor complications, preoperative Cobb angle, number of growing rods, age, and number of levels instrumented were performed using a significance level of p Results Thirty-four patients had rib-anchored growing rods and 142 had spine-anchored growing rods. This analysis found that proximal rib-anchored growing rods have a 23% risk of lifetime rod breakage compared with spine-anchored growing rods (6% vs. 29%) (p = .041) without a significant increase in risk of anchor complications (38% vs. 33%) (p = .117). The number of implanted rods (p = .839), age (p = .649), and number of instrumented levels (p = .447) were not statistically significant regarding rod breakage risk, although higher preoperative Cobb angles were significant (p = .014). Conclusions Preoperative Cobb angle appears to be the most influential factor in determining whether growing rods break (p = .014). Univariate analysis found that rib anchors were associated with less than one-fourth the risk of rod breakage than spine anchors (p = .04) but multivariate analysis found no significant association between anchors and rod breakage (p = .07). This trend suggests that rib-anchored growing rod systems may be associated with less rod breakage because the system is less rigid as a result of some “slop” at the hook–rib interface, as well as the normal motion of the costovertebral joint.

Nutritional improvement following growing rod surgery in children with early onset scoliosis

Abstract: Purpose We aimed to evaluate the nutritional status of children with early onset scoliosis (EOS) and to determine if treatment with growing rod instrumentation improves weight percentile. Methods Data was retrospectively collected on 88 EOS patients treated with growing rods at six institutions. Mean age at surgery was 5.8 years, and mean Cobb angle was 75. All patients were followed for at least 2 years (mean 4 years). Weights were converted to normative percentiles based on the patients’ age and gender. Results Preoperatively, 47 % (41/88) of patients were\5 percentile for weight, thus failing to thrive. There was a significant increase in mean postoperative weight percentiles at latest follow-up (p = 0.004). 49 % of patients gained weight, with a mean of 18 percentile. A significant relationship exists between age at initial surgery and percentile weight gain (p \ 0.005), with children \4 years old not demonstrating postoperative improvement. This relationship was not confounded by preoperative weight, preoperative Cobb angle, or years of follow-up (p [ 0.05). Children with neuromuscular and syndromic diagnoses do not appear to improve their mean nutritional status after surgery when compared to patients with idiopathic or congenital/structural scoliosis (p = 0.006). Conclusion Following growing rod treatment, there was significant improvement in nutritional status in approximately 50 % of patients, similar to that reported with VEPTR. Neuromuscular and syndromic patients did not experience nutritional improvement post-operatively. These findings support the theory that growing rods improve the clinical status of EOS patients, as nutritional improvement is one outcome of improved clinical status. The relationship between age at initial surgery and nutritional improvement is intriguing.

Biomechanical Evaluation of 4 Different Foundation Constructs Commonly Used in Growing Spine Surgery: Are Rib Anchors Comparable to Spine Anchors?

Abstract: Study Design In vitro animal model. Objective To compare the strength of 4 different anchor constructs commonly used as foundations in growing spine surgery. Summary of Background Data Children with progressive early-onset scoliosis often require surgical intervention to control the deformity and allow continued growth. The foundation sites of growing spine constructs take a significant load and can fail. This study compares the strength of 4 commonly used constructs applying the same load in a porcine model. Methods Forty immature porcine specimens including soft tissues (10 per group) were instrumented with 1 of 4 bilateral proximal anchors at T5–T6. The four groups were: screw–screw (SS), lamina hook–hook (HH), rib hook–hook (RR), and transverse process to lamina hook–hook (TPL). The entire specimen was kept intact except for surgical site exposure. A unique fixture was designed to brace the specimen and provide a counterforce. The ultimate load was identified as the greatest load recorded for a construct and analyzed by a set of 1-way analysis of variance using the SPSS 12.0 statistical package. Results All specimens eventually failed at the bone–anchor interface. No failures were observed in the instrumentation used. The means and standard deviations of ultimate loads were measured as RR (429 ± 133 N), SS (349 ± 89 N), HH (283 ± 48 N), and TPL (236 ± 60 N). There was no statistically significant difference between the following construct pairs: RR/SS, SS/HH, and HH/TPL. Young's modulus was calculated for each construct type and no statistically significant difference was determined. Conclusions This study showed that RR and SS constructs had the greatest ultimate strength but also the greatest variability among the foundations tested. However, the HH and TPL constructs had lower ultimate strength but were less variable. Rib-based anchors may be considered as an alternative in upper foundation constructs in growing rod techniques.

Surgeon practices regarding infection prevention for growth friendly spinal procedures

Abstract: Purpose The rate of infection in patients having growth sparing surgery for early onset scoliosis has been reported up to 25 % during the course of treatment. A recent study demonstrated significant variability in the approach to infection prevention in adolescent and neuromuscular scoliosis. The purpose of this study is to conduct a similar survey in order to understand approaches used by experienced pediatric spinal surgeons with regard to infection prevention in growth friendly spinal procedures. Materials and methods After preliminary internal testing of a survey by the authors, a final 21-question survey was created and approved by the authors and electronically distributed to all members of the Chest Wall Spinal Deformity Study Group and the Growing Spine Study Group (n = 57). A total of 40 responses were obtained (70 %). Results Significant variability in practice was demonstrated across the majority of the questions answered. Several of the questions demonstrated relative equipoise between practices, including preoperative MRSA screening, preoperative chlorhexidine baths, postoperative antibiotic duration after insertion, use of topical antibiotics, use of drains, use of IV gram negative coverage or vancomycin, and skin preparation. Conclusion Other studies have demonstrated that variability in practice may have a negative impact on clinical outcomes, so one could postulate that steps that can reduce variability in the current population may help improve outcomes in this population. Areas of clinical equipoise can be used to help design and direct multicenter studies with an ultimate goal of reducing infections in this population. Level of evidence Level V.

Preoperative Planning for Pedicle Subtraction Osteotomy: Does Pelvic Tilt Matter?

Abstract: Study Design Multicenter, retrospective radiographic analysis. Objectives To evaluate the impact that preoperative spinopelvic parameters have on postoperative sagittal vertical axis (SVA). The researchers hypothesized that patients with a large preoperative pelvic tilt (PT) would require more extensive lumbar pedicle subtraction osteotomy (LPSO) procedures to reestablish anatomic postoperative SVA than patients with normal preoperative PT. Summary of Background Data Restoration of anatomic sagittal spinal alignment has been demonstrated to improve clinical outcomes. However, the degree to which spinopelvic parameters contribute to sagittal spinal malalignment is poorly understood. Methods Multicenter, retrospective analysis of 183 consecutively enrolled adult spinal deformity patients treated with LPSO procedures for correction of sagittal malalignment. Preoperative and postoperative freestanding full-length sagittal X-rays were analyzed for regional curves, pelvic parameters, and global alignment. Only patients with a preoperative SVA greater than 10 cm and a postoperative SVA less than 5 cm were retained for analysis. Patients were divided into 2 groups according to preoperative PT (low PT, less than 30°; and high PT, ≥30°). Independent t test analysis was used to determine differences in correction required to achieve postoperative SVA less than 5 cm. Results A total of 55 patients were identified for analysis. Low PT (n = 30) had lower preoperative PT than high PT (n = 25; 25° vs. 42°, respectively; p Conclusions This study demonstrates that patients with high PT in conjunction with sagittal spinal malalignment require larger lumbar osteotomy procedures, including a greater osteotomy resection and larger lumbar lordosis correction, to obtain a satisfactory postoperative SVA. Surgeons performing LPSO procedures must evaluate preoperative spinopelvic parameters, including PT, to avoid undercorrection and residual deformity after complex sagittal realignment procedures.

How Does a Novel Monoplanar Pedicle Screw Perform Biomechanically Relative to Monoaxial and Polyaxial Designs

Abstract: Background Minimally invasive spinal fusions frequently require placement of pedicle screws through small incisions with limited visualization. Polyaxial pedicle screws are favored due to the difficulty of rod insertion with fixed monoaxial screws. Recently, a novel monoplanar screw became available that is mobile in the coronal plane to ease rod insertion but fixed in the sagittal plane to eliminate head slippage during flexion loads; however, the strength of this screw has not been established relative to other available screw designs.

The Use of Pedicle Screws in Children 10 Years of Age and Younger With Growing Rods

Abstract: Study Design Retrospective review of a multicenter database. Objectives To evaluate the incidence of implant-related complications of pedicle screws versus hooks in children with early-onset scoliosis treated with growing rods. Summary of Background Data Because growing rods have a high rate of implant complications compared with spinal fusion, this challenging, fusionless group of patients is a provocative environment in which to evaluate implant-related complications of pedicle screws. Methods A total of 159 patients with growing rods treated at 18 institutions were included. Inclusion criteria were children aged less than 10 years who had growing rod surgery between 1998 and 2008 with minimum 2-year follow-up from index surgery. Charts and radiographs were evaluated only for complications directly related to a pedicle screw or hook. The researchers evaluated 464 pedicle screws and 643 hooks. Results Of the 464 pedicle screws, there were 17 complications (3.7%) directly related to screws: acute loss of fixation (2), migration (14), and breakage (1). Of the 643 hooks, there were 47 complications (7.3%): acute loss of fixation (28), migration (16), and unspecified loss of fixation (3). When loss of fixation occurred, the mean time to loss of fixation was similar for both implants: 33 months for hooks and 30 months for screws (p = .95). There were no complications involving neurologic or vascular injury directly related to a hook or screw. Conclusions Pedicle screws in growing rod constructs had fewer implant-related complications than hooks in patients with early-onset scoliosis in a minimum 2-year follow-up period (p = .02). It is encouraging that there were no neurological or vascular injuries associated with either implant in 159 children with over 4.5 years of mean follow-up, in a provocative, fusionless environment.

Is There an Optimal Time to Distract Dual Growing Rods

Abstract: Study Design Retrospective multicenter observational cohort study. Objectives To determine whether there is a significant difference in final spinal height achieved, instrumented height, or Cobb angle related to the mean time interval between distractions of dual growing rods. Summary of Background Data Patients were prospectively enrolled in “The Treatment of Progressive Early Onset Spinal Deformities: A Multi-Center Study.” Additional data were collected via a retrospective review of medical records. Methods Using data from a multicenter database, the authors identified 46 patients (23 boys and 23 girls) with early-onset scoliosis who were treated with dual growing rods and who had surgical treatment spanning more than 4 years. The patients were divided into 2 groups: those who had less than 9 months (16 patients) and those who had 9 months or more (30 patients) between distractions. Standard univariate statistics were calculated. The researchers performed 2-tailed t tests. Significance was set at p = .05. Results The differences in primary Cobb angle, T1–S1 height, and instrumented segment length at the last distraction or final arthrodesis, compared with the post-index procedure values, were not significantly different (p = .52, .58, and .60, respectively) between groups with the available data. The normalized instrumented height gains, in millimeters per year, were not significantly different (p = .22). Conclusions Patients with longer times between growing-rod distractions (9 or more months) had no significant differences in primary Cobb angle, T1–S1 length, or instrumented length gain compared with patients with shorter times (less than 9 months) between distractions.

Distraction-based treatment maintains predicted thoracic dimensions in early-onset scoliosis

Abstract: Study Design Retrospective cohort study. Objective Examination of distraction-based treatment effect on thoracic dimensions in patients compared to predicted individual normal values, at initial treatment and subsequent follow-up after lengthenings. Summary of Background Data Change in thoracic dimensions and spine length is an important outcome measure in treatment of children with early-onset scoliosis; however, it is difficult to use to make comparisons between patients and the normal population because of the heterogeneous nature of early-onset scoliosis. Methods Early-onset scoliosis patients treated with distraction-based therapy who had radiographic parameters (pelvic inlet width, chest width, and thoracic height) preoperatively, immediately postoperatively, and at a minimum 5-year follow-up were included. Individual thoracic measurements were compared with predicted normal measures based on pelvic inlet width, and expressed as a percentile of predicted measure. Results Comparisons were made in 41 patients; mean age at time of primary surgery was 4.5 years, and median follow-up was 6.5 years. Thoracic height percentile increased from a mean preoperative value of .78 to a postoperative percentile of .88 (p Conclusions Distraction-based treatment increases absolute thoracic height over time. There is significant improvement in the thoracic height percentile normalized after initial surgery, which was maintained over time. Measuring expected gains as a percentile normalized for pelvic width may be a more relevant outcome measure compared with measuring only absolute values.

Do Thoracolumbar/lumbar Curves Respond Differently to Growing Rod Surgery Compared With Thoracic Curves?

Abstract: Study Design Retrospective study. Objectives To compare radiographic outcomes between primary thoracic and primary thoracolumbar/lumbar curves in patients with early-onset scoliosis (EOS) after growing rod (GR) surgery. Summary of Background Data Previous studies have shown the efficacy of GR surgery for progressive EOS. However, there is no information on the behavior of different curve patterns in EOS after GR surgery. Methods A multicenter international EOS database query identified 175 patients who met the following inclusion criteria: non-congenital etiology, GR surgery, ≤ 10 years of age at index surgery, minimum 2-year follow-up, and at least 3 lengthenings. Patients were categorized into 2 groups based on the Scoliosis Research Society definition of the anatomical location of primary curves: group 1 included thoracic apices (T2 to T11/12 disc) and group 2 included thoracolumbar (T12 to L1) and lumbar (L1/2 disc to L4) apices. Radiographic measurements were performed before and after index surgery and at latest follow-up. Results A total of 139 patients (79%) had primary thoracic (group 1) and 36 (21%) had primary thoracolumbar or lumbar curves (group 2). Mean number of levels instrumented was statistically greater in group 2 (15.0) versus group 1 (13.6) (p .05). Implant complication rate was 45% and 47% for groups 1 and 2, respectively. Preoperative curve flexibility was greater in group 2 (45%) compared with group 1 (40%) (p > .05). Conclusions Overall, thoracolumbar/lumbar and thoracic curves achieve similar major curve correction and have a similar complication profile.

The Biological Effects of Combining Metals in a Posterior Spinal Implant: In Vivo Model Development Report of the First Two Cases

Abstract: Study Design. Combinations of metal implants (stainless steel (SS), titanium (Ti), and cobalt chrome (CC)) were placed in porcine spines. After 12 months, tissue response and implant corrosion were compared between mixed and single metal junctions. Objective. Model development and an attempt to determine any detriment of combining different metals in posterior spinal instrumentation. Methods. Yucatan mini-pigs underwent instrumentation over five unfused lumbar levels. A SS rod and a Ti rod were secured with Ti and SS pedicle screws, SS and Ti crosslinks, SS and CC sublaminar wires, and Ti sublaminar cable. The resulting 4 SS/SS, 3 Ti/Ti, and 11 connections between dissimilar metals per animal were studied after 12 months using radiographs, gross observation, and histology (foreign body reaction (FBR), metal particle count, and inflammation analyzed). Results. Two animals had constructs in place for 12 months with no complications. Histology of tissue over SS/SS connections demonstrated 11.1 ± 7.6 FBR cells, 2.1 ± 1.7 metal particles, and moderate to extensive inflammation. Ti/Ti tissue showed 6.3 ± 3.8 FBR cells, 5.2 ± 6.7 particles, and no to extensive inflammation (83% extensive). Tissue over mixed components had 14.1 ± 12.6 FBR cells and 13.4 ± 27.8 particles. Samples surrounding wires/cables versus other combinations demonstrated FBR (12.4 ± 13.5 versus 12.0 ± 9.6 cells, P = 0.96), particles (19.8 ± 32.6 versus 4.3 ± 12.7, P = 0.24), and inflammation (50% versus 75% extensive, P = 0.12). Conclusions. A nonfusion model was developed to study corrosion and analyze biological responses. Although no statistical differences were found in overlying tissue response to single versus mixed metal combinations, galvanic corrosion between differing metals is not ruled out. This pilot study supports further investigation to answer concerns when mixing metals in spinal constructs.

Paper #35: Pelvic Anchor Outcomes in Growing Rod Constructs: An Analysis of Patients With a Minimum of 4 Years of Postoperative Follow-up

Abstract: Disclosures: J.T. Brooks: None. A. Jain: None. F.S. Perez-Grueso: A; Depuy Synthes. D.L. Skaggs: B; Medtronic, Biomet. C; Stryker, Biomet, Medtronic. F; Biomet, Wolters Kluwer Health Lippincott Williams & Wilkins. G.H. Thompson: F; Lippincott. B.A. Akbarnia: A; Depuy Synthes, Nuvasive. B; Nuvasive, K Spine, Ellipse, K2M. D; Alphatec Spine, Nocimed, Nuvasive, K Spine, Ellipse. F; K2M, DePuy Synthes, Nuvasive, Springer. P.D. Sponseller: A; Depuy Synthes. B; Depuy Synthes. F; Globus Medical, Depuy Synthes, Journal of Bone and Joint Surgery, Oakstone Medical. G. Study Group: A; Growing Spine Foundation.

Anterior Column Realignment (ACR): Minimally Invasive Surgery for the Treatment of Adult Sagittal Plane Deformity

Abstract: Adult sagittal plane alignment is the result of an intricate interaction between the spine and pelvis. The development of a sagittal spine deformity results in a series of compensatory mechanisms including increase in pelvic tilt, hip extensor overutilization, and knee and ankle flexion. When these natural mechanisms fail, patients may develop symptomatic sagittal imbalance, which ultimately affects their function and quality of life.