Establishing Consensus on the Best Practice Guidelines for Use of Halo Gravity Traction for Pediatric Spinal Deformity.

BACKGROUND: Although halo gravity traction (HGT) has been used to treat children with severe spinal deformity for decades, there is a distinct lack of high-quality evidence to speak to its merits or to dictate ideal manner of implementation. In addition, no guidelines exist to drive research or assist surgeons in their practice. The aim of this study was to establish best practice guidelines (BPG) using formal techniques of consensus building among a group of experienced pediatric spinal deformity surgeons to determine ideal indications and implementation of HGT for pediatric spinal deformity. METHODS: The Delphi process and nominal group technique were used to formally derive consensus among leaders in pediatric spine surgery. Initial work identified significant areas of variability in practice for which we sought to garner consensus. After review of the literature, 3 iterative surveys were administered from February through April 2018 to nationwide experts in pediatric spinal deformity. Surveys assessed anonymous opinions on ideal practices for indications, preoperative evaluation, protocols, and complications, with agreement of 80% or higher considered consensus. Final determination of consensus items and equipoise were established using the Nominal group technique in a facilitated meeting. RESULTS: Of the 42 surgeons invited, responses were received from 32, 40, and 31 surgeons for each survey, respectively. The final meeting included 14 experts with an average 10.5 years in practice and average 88 annual spinal deformity cases. Experts reached consensus on 67 items [indications (17), goals (1), preoperative evaluations (5), protocols (36), complications (8)]; these were consolidated to create final BPG in all categories, including statements to help dictate practice such as using at least 6 to 8 pins under 4 to 8 lbs of torque, with a small, tolerable starting weight and reaching goal weight of 50% TBW in ∼2 weeks. Nine items remained items of equipoise for the purposes of guiding future research. CONCLUSIONS: We developed consensus-based BPG for the use and implementation of HGT for pediatric spinal deformity. This can serve as a measure to help drive future research as well as give new surgeons a place to begin their practice of HGT. LEVEL OF EVIDENCE: Level V-expert opinion.

Coronal decompensation following thoracic vertebral body tethering in idiopathic scoliosis.

PURPOSE: Post-operative coronal decompensation (CD) continues to be a challenge in the treatment of adolescent idiopathic scoliosis (AIS). CD following selective spinal fusion has been studied. However, there is currently little information regarding CD following Vertebral Body Tethering (VBT). Thus, the goal of this study is to better understand the incidence and risk factors for CD after VBT. METHODS: Retrospective review of a prospective multicenter database was used for analysis. Inclusion criteria were patients undergoing thoracic VBT, a minimum 2-year follow-up, LIV was L1 or above, skeletally immature (Risser ≤ 1), and available preoperative and final follow-up AP and lateral upright radiographs. Radiographic parameters including major and minor Cobb angles, curve type, LIV tilt/translation, L4 tilt, and coronal balance were measured. CD was defined as the distance between C7PL and CSVL > 2 cm. Multiple logistic regression model was used to identify significant predictors of CD. RESULTS: Out of 136 patients undergoing VBT, 94 patients (86 female and 6 male) met the inclusion criteria. The mean age at surgery was 12.1 (9-16) and mean follow-up period was 3.4 years (2-5 years). Major and minor curves, AVR, coronal balance, LIV translation, LIV tilt, L4 tilt were significantly improved after surgery. CD occurred in 11% at final follow-up. Lenke 1A-R (24%) and 1C (26%) had greater incidence of CD compared to 1A-L (4%), 2 (0%), and 3 (0%). LIV selection was not associated with CD. Multivariate logistic regression analysis yielded 1A-R and 1C curves as a predictor of CD with the odds ratio being 17.0. CONCLUSION: CD occurred in 11% of our thoracic VBT patients. Lenke 1A-R and 1C curve types were predictors for CD in patients treated with VBT. There were no other preoperative predictors associated with CD.

Analysis of three-dimensional spine growth for vertebral body tethering patients at 2 and 5 years post operatively.

PURPOSE: Scoliosis can be treated with vertebral body tethering (VBT) as a motion-sparing procedure. However, the knowledge of how growth is affected by a tether spanning multiple levels is unclear in the literature. Three-dimensional true spine length (3D-TSL) is a validated assessment technique that accounts for the shape of the spine in both the coronal and sagittal planes. This study aimed to assess if 3D-TSL increases over a five-year period after VBT implantation in thoracic curves for idiopathic scoliosis. METHODS: Prospectively collected radiographic data from an international pediatric spine registry was analyzed. Complete radiographic data over three visits (post-operative, 2 years, and 5 years) was available for 53 patients who underwent VBT. RESULTS: The mean age at instrumentation of this cohort was 12.2 (9-15) years. The average number of vertebrae instrumented was 7.3 (SD 0.7). Maximum Cobb angles were 50° pre-op, which improved to 26° post-op (p < 0.001) and was maintained at 5 years (30°; p = 0.543). Instrumented Cobb angle was 22° at 5 years (p < 0.001 vs 5-year maximum Cobb angle). An accentuation was seen in global kyphosis from 29° pre-operative to 41° at 5 years (p < 0.05). The global spine length (T1-S1 3D-TSL) started at 40.6 cm; measured 42.8 cm at 2 years; and 44.0 cm at the final visit (all p < 0.05). At 5 years, patients reached an average T1-S1 length that is comparable to a normal population at maturity. Immediate mean post-operative instrumented 3D-TSL (top of UIV-top of LIV) was 13.8 cm two-year length was 14.3 cm; and five-year length was 14.6 cm (all p < 0.05). The mean growth of 0.09 cm per instrumented level at 2 years was approximately 50% of normal thoracic growth. Patients who grew more than 0.5 cm at 2 years had a significantly lower BMI (17.0 vs 19.0, p < 0.05) and smaller pre-operative scoliosis (48° vs 53°, p < 0.05). Other subgroup analyses were not significant for age, skeletal maturity, Cobb angles or number of spanned vertebras as contributing factors. CONCLUSIONS: This series demonstrates that 3D-TSL increased significantly over the thoracic instrumented levels after VBT surgery for idiopathic scoliosis. This represented approximately 50% of expected normal thoracic growth over 2 years.

Surgical outcomes for spinal deformity in osteogenesis imperfecta.

STUDY DESIGN: IRB approved retrospective review of the the SHOnet (Shriners Health Outcomes Network). OBJECTIVES: Osteogenesis imperfecta (OI) is the most prevalent genetic disorder of bone and connective tissue in the pediatric population, with an incidence of 1/15,000-20,000. Scoliosis has been reported to be present in 39-100% of OI patients and may continue to progress into adulthood but there is little information on the perioperative outcomes, rates of revision surgery and complications in this fragile population. The purpose of this study is to examine the prevalence of scoliosis in the OI population across a tertiary care multihospital system. The rate at which these patients progress to surgery, the perioperative complication rate and if there is an association between complications and age at surgical intervention, pre-operative Cobb angle, number of fractures, and type of OI. Incidence of scoliosis in OI may be lower than previously reported, many may never require surgical intervention and those that do require surgical intervention have an 8% reoperation rate at an average of 3.3 years postop. METHODS: IRB approved retrospective review of the the SHOnet (Shriners Health Outcomes Network), electronic health record data warehouse from January 1, 2011 and December 31, 2017. Inclusion criteria included International Classification of Diseases (ICD) code for osteogenesis imperfecta and scoliosis. The data warehouse was queried for age, gender, presence of vertebral body fractures, proximal junctional kyphosis, basilar invagination, bisphosphonate use, and perioperative complications including postoperative infection. RESULTS: There were 2372 patients with osteogenesis imperfecta, 429 or 18.1% also had a diagnosis of scoliosis, while 81.9% did not (see Table 1). Only 74 patients (17.2%) of the patients that had scoliosis underwent spine surgery, 12 of which had staged surgery with an average preop thoracic Cobb 58.18 (range 7-115), and thoracolumbar Cobb 59.83 (range 5-145). Six patients (8%) required revision spine surgery. Average time to revision was 3.88 years (6.9-69mo). Bisphosphonate use was present in 35.5% of patients that did not require surgery and in 40.5% that did. CONCLUSION: With over 2300 patients, this is the largest study to date on scoliosis in patients with OI. We found that contrary to prior studies which had indicated the incidence of scoliosis ranges from 39 to 100% that it was only present in 18% of our patients. This indicates that the incidence of scoliosis in OI is potentially lower than previously reported, though due to the nature of this study it may be underreported. Furthermore, only 17% of those patients in our study with scoliosis eventually underwent surgery. It is important to note that many patients treated non-operatively had deformity within the operative range, which may indicate that they were not considered good candidates for surgical intervention. Lastly, we found that bisphosphonate use did not appear to affect the likelihood of progression to surgery in this group of patients, though this may be due to later initiation of the bisphosphonate use.

Thoracolumbar curve behavior after selective thoracic anterior vertebral body tethering in Lenke 1A vs Lenke 1C curve patterns.

STUDY DESIGN: Retrospective review of a prospective database. OBJECTIVES: The purpose of this study is to evaluate changes in the thoracic and thoracolumbar/lumbar curves and truncal balance in patients treated with selective thoracic anterior vertebral body tethering (AVBT) with Lenke 1A vs 1C curves at a minimum of 2 years follow-up. Lenke 1C curves treated with selective thoracic AVBT demonstrate equivalent thoracic curve correction and reduced thoracolumbar/lumbar curve correction compared to Lenke 1A curves. Additionally, at the most recent follow-up, both curve types demonstrate comparable coronal alignment at C7 and the lumbar curve apex, though 1C curves have better alignment at the lowest instrumented vertebra (LIV). Rates of revision surgery are equivalent between the two groups. METHODS: A matched cohort of 43 Risser 0-1, Sanders Maturity Scale (SMS) 2-5 AIS pts with Lenke 1A (1A group)and 19 pts with Lenke 1C curves (1C group) treated with selective thoracic AVBT and a minimum of 2-year follow-up were included. Digital radiographic software was used to assess Cobb angle and coronal alignment on preoperative, postoperative and subsequent follow-up radiographs. Coronal alignment was assessed by measuring the distance from the center sacral vertical line (CSVL) to the midpoint of the LIV, apical vertebra for thoracic and lumbar curves and C7. RESULTS: There was no difference in the thoracic curve measured preoperatively, at first erect, pre-rupture or at the most recent follow-up, nor was there a significant difference in C7 alignment (p = 0.057) or apical thoracic alignment (p = 0.272) between the 1A and 1C groups. Thoracolumbar/lumbar curves were smaller in the 1A group at all-time points. However, there was no significant difference between the percent correction between the two groups thoracic (p = 0.453) and thoracolumbar/lumbar (p = 0.105). The Lenke 1C curves had improved coronal translational alignment of the LIV at the most recent follow-up p = 0.0355. At the most recent follow-up the number of patients considered to have successful curve correction (Cobb angle correction of both the thoracic and thoracolumbar//lumbar curves to ≤ 35 degrees), was equivalent between Lenke 1A and Lenke 1C curves (p = 0.80). There was also no difference in the rate of revision surgery between the two groups (p = 0.546). CONCLUSION: This is the first study to compare the impact of lumbar curve modifier type on outcomes in thoracic AVBT. We found that Lenke 1C curves treated with selective thoracic AVBT demonstrate less absolute correction of the thoracolumbar/lumbar curve at all time points but have equivalent percent correction of the thoracic and thoracolumbar/lumbar curves. The two groups have equivalent alignment at C7 and the thoracic curve apex, and Lenke 1C curves have better alignment at the LIV at the most recent follow-up. Furthermore, they have an equivalent rate of revision surgery compared to Lenke 1A curves. Selective thoracic AVBT is a viable option for selective Lenke 1C curves, but despite equivalent correction of the thoracic curve, there is less correction of the thoracolumbar/lumbar curve at all-time points.

Outcomes of MCGR at > 3 year average follow-up in severe scoliosis: who undergoes elective revision vs UPROR?

PURPOSE: The purpose of this study was to evaluate mid-term outcomes of magnetically controlled growing rods (MCGR), evaluate factors associated with unplanned return to the operating room (UPROR) vs achieving full length. Full length was defined as achieving > 85% of the elongating portion of the rod. METHODS: IRB approved retrospective single site study. 106 patients underwent MCGR between 2014 and 2020, 58 met inclusion criteria, all genders, ethnicities, and etiologies were included. Patients with < 1 year follow-up or previous instrumentation were excluded. RESULTS: Follow-up averaged 43 months. 23 patients achieved full length 13 were revised to a new MCGR and 10 to a fusion; 5 were fused due to skeletal maturity; 12 were still lengthening; 2 were being observed; 16 experienced UPROR. Major curves improved from 80° (50-114) preoperative to 40° (7-78) at most recent follow-up or prior to revision, and 24° (4-57) after fusion. Fusion patients averaged 1.3 (1-4) procedures prior to fusion and gained 75 mm (38-142) in T1-S1 length. 16 patients experienced UPROR, 11 were male (p = 0.0238). All failures to elongate were male as was the rod fracture. Age was not correlated with UPROR (p = 0.318), but did correlate with implant-specific causes of UPROR. Specifically, anchor failure was associated with younger age and rod failure with older age at implantation (p = 0.013). There was no correlation between UPROR and major curve, flexibility or kyphosis. CONCLUSION: This is the largest site study evaluating mid-term outcomes in MCGR patients. At > 3.5 year follow-up 47% were electively revised, 27% underwent UPROR, 26% were still lengthening, and 3% were being observed. UPROR was associated with male gender and age at implantation was associated with implant-related causes of UPROR. MCGR continues to have high complication rates, better knowledge of MCGR outcomes may improve patient education, surgical timing, and decision-making.

Correlation of collagen X biomarker (CXM) with peak height velocity and radiographic measures of growth in idiopathic scoliosis.

STUDY DESIGN: Prospective comparative study. OBJECTIVES: Evaluate the correlation of CXM with established measures of growth. Theoretically higher CXM levels would correlate with rapid longitudinal bone growth and lower levels with growth cessation. Assessment of growth status in patients with pediatric spinal deformity is critical. The current gold standards for assessing skeletal maturity are based on radiographic measures and have large standard errors (SE). Type X collagen (COLX) is produced in the growing physis during enchondral ossification. CXM is a COLX breakdown product that can be measured in blood products. CXM, thus, is a direct measure of enchondral ossification. METHODS: IRB-approved prospective study. Q6mo anthropometrics and spine PA biplanar slot scanner images including the hand were assessed for major Cobb, Risser score (RS), triradiate cartilage status (TRC), Greulich and Pyle bone age (BA), and Sanders Score (SS). Serial dried blood spots (DBS) to obtain CXM levels were collected 3 consecutive days Q1-2 months based on SS. RESULTS: 47 idiopathic scoliosis patients, Cobb ≥ 20 were enrolled. Mean enrollment age was 11.8 years (range 7.1-16.6 years). 3103 DBS samples were assayed in quadruplicate. CXM results were highly reproducible with a 3% intraassay coefficient of variation (CV), and 12% interassay CV%. The CXM 3-day average was significantly correlated with BA R = 0.9, p < 0.001, RS R = 0.6, p < 0.001, SS R = 0.7, p < 0.001 and with height R = 0.7, p < 0.001. No patient with a CXM level < 5 ng/ml had remaining growth. CONCLUSION: CXM is the first identifiable biomarker specific to longitudinal bone growth. Early results indicate that it is a patient-specific, real-time measure of growth velocity with high correlation to the established anthropometric and radiographic measures of growth. It is predictive of cessation of growth. It is highly reproducible with a low SE. Long-term follow-up is required to determine the ability of CXM to guide clinical decision-making.

Infantile Idiopathic Scoliosis: Factors Affecting EDF Casting Success.

STUDY DESIGN: IRB-approved retrospective single cohort study. OBJECTIVES: To review our ten-year history with EDF (Elongation Derotation Flexion) casting in patients with infantile idiopathic scoliosis (IIS) to better understand which factors predict successful outcomes. SUMMARY OF BACKGROUND DATA: Numerous studies have demonstrated the efficacy of EDF casting in the treatment of progressive infantile idiopathic scoliosis. But none have reproduced the success of Mehta's even with early intervention. METHODS: Patients with IIS treated with EDF casting with a minimum 24-month follow-up were included. Radiographs and clinical records were reviewed. Age, sex, and curve type were documented. Precast, traction, in cast, in brace, and final Cobb angles were measured and recorded. Outcomes were defined by Cobb angle at final follow-up out of cast or brace. Patients were considered cured if the final Cobb angle was <10°, palliated at 10°-45°, and failed if they required surgical treatment. RESULTS: Sixty-three patients with IIS were reviewed. Thirty-two were excluded for incomplete records or insufficient follow-up, leaving 31 patients. No patients progressed to surgical intervention during the study. Patients with a Cobb angle >10° in the final cast were 7.3 times more likely to fall into the palliative range at the most recent follow-up than if their Cobb angle was 10° or less even when adjusted for age. Earlier age at onset of casting (14.9 vs. 21.1 months) was not statistically significant (p=.073). Magnitude of initial curvature, flexibility, initial correction, sex, and curve type were also not found to be significant. CONCLUSION: EDF casting is a valid treatment option for IIS with a high cure rate. Major Cobb angle at the end of casting is most predictive of outcome. Cobb angles >10° at the end of casting had a 7.3 times greater risk of falling into the palliated category versus Cobb angles less than or equal to 10° even when adjusted for age. Initial curve magnitude, curve flexibility, sex, and curve type were not predictive. LEVEL OF EVIDENCE: Level IV.