Preliminary Study of Motion Preservation Following Posterior Dynamic Distraction Device in Adolescent Idiopathic Scoliosis Patients.

BACKGROUND: Motion-sparing scoliosis surgeries such as the posterior dynamic distraction device (PDDD) are slowly increasing in use. However, there is limited clinical data documenting postoperative motion across the PDDD construct. With this cohort study, we aim to measure sagittal and coronal motion following PDDD. We hypothesize coronal and sagittal spinal motion will be partially preserved across the construct. METHODS: Retrospective review of prospectively collected data. Preoperative and minimum 1-year postoperative coronal range of motion across the instrumented levels was compared. Available flexion/extension radiographs were evaluated postoperatively to assess sagittal arc of motion. Radiographs from latest follow-up were used. RESULTS: At a mean of 1.9 years (1 to 5 y), flexibility radiographs were available on 29 patients treated with PDDD (17 thoracic, 12 lumbar). Mean age at surgery was 16 years (12 to 25). Postoperative coronal arc of motion in PDDD patients was 11 degrees (3 to 19 degrees) in the thoracic spine and 10 degrees (0 to 28 degrees) in the lumbar spine. Compared with preoperative motion, the thoracic arc of motion was maintained by 33% (35 to 11 degrees) and lumbar motion was maintained by 30% (34 to 10 degrees). Flexion-extension radiographs were available on 7 patients. Sagittal arc for the upper instrumented vertebral end plate to the lower instrumented vertebral endplate of the cohort was 10 degrees in the thoracic spine (6 to 18) and 14 degrees in the lumbar spine (5 to 21). Sagittal measurements for the changes in the arc of the upper and lower screws on the construct were 4 degrees in the thoracic group (2 to 8) and 9 degrees in the lumbar group (2 to 17). By latest follow-up 11 patients (38%) underwent reoperation, with most cases due to implant breakage (N=4, 14%), extender misalignment (N=2, 7%), and screw misplacement (N=2, 7%). CONCLUSION: At mean 1.9 years postoperatively, PDDD preserves measurable spinal motion over the construct both in the coronal and the sagittal plane without evidence for autofusion. Coronal arc of motion averages 10 to 12 degrees and sagittal arc of motion ranged from 4 to 14 degrees, although this varies by patient. This study confirms that PDDD for pediatric scoliosis preserves a measurable degree of postoperative flexibility both in the sagittal and coronal planes. LEVEL OF EVIDENCE: Level II-therapeutic study.

Rib-on-Pelvis Deformity and Reported Pain in Neuromuscular Early-Onset Scoliosis.

BACKGROUND: Neuromuscular early-onset scoliosis (N-EOS) often presents with a long sweeping thoracolumbar scoliosis and pelvic obliquity. With severe pelvic obliquity, the ribs come into contact with the high side of the pelvis, termed rib-on-pelvis deformity (ROP). The goal of this study is to evaluate whether ROP is associated with reported pain and other health-related quality of life (HRQOL) measures. We hypothesize that ROP is associated with increased pain and negative HRQOL. METHODS: A multicenter international registry was queried for all nonambulatory patients with N-EOS from 2012 to 2022. Both surgical and nonsurgical patients were included. ROP was classified as a binary radiographic assessment of preoperative (surgical patients) and most recent follow-up (nonsurgical patients) upright radiographs. Reported pain and other HRQOL measures were assessed through the 24-Item Early Onset Scoliosis Questionnaire (EOSQ-24). Patients with nonupright radiographs or EOSQ-24 questionnaires and corresponding radiographs >4 months apart were excluded. RESULTS: Totally, 225 patients (8.4±3.1 y, 55% female) were included. The median major curve was 63.3 (IQR: 40.6 to 81.2) degrees and median pelvic obliquity was 15.5 degrees (IQR: 8.8 to 26.4). Eighty-three patients (37%) had ROP. ROP was associated with both frequency (P<0.001) and severity (P<0.001) of pain. ROP was associated with worse general health (P=0.01), increased difficulty with vocalization (P=0.02), increased frequency of shortness of breath (P=0.002), and increased difficulty sitting upright (P=0.04). Regarding overall EOSQ-24 domains, ROP was associated with worse general health, pain/discomfort, pulmonary function, and physical function (P<0.01). In a subanalysis of 76 patients who underwent surgical intervention with at least 2 years of follow-up, patients with preoperative ROP experienced significantly greater improvements in both frequency (P=0.004) and severity (P=0.001) of pain than the patients without preoperative ROP at 2 years postoperatively. CONCLUSIONS: The overall incidence of ROP in N-EOS is about 37%. ROP is associated with greater pain and worse HRQOL through the EOSQ-24 questionnaire. Furthermore, these patients experienced a greater reduction in pain after surgery. Clinicians and parents must be aware that ROP is possibly a pain generator, but responds positively to surgical intervention. LEVEL OF EVIDENCE: Level III.

The Fate of The Broken Tether: How Do Curves Treated with Vertebral Body Tethering Behave After Tether Breakage?

STUDY DESIGN: Retrospective, Multicenter. OBJECTIVE: Assess curve progression and occurrence of revision surgery following tether breakage after vertebral body tethering (VBT). SUMMARY OF BACKGROUND DATA: Tether breakage after VBT is common with rates up to 50% reported. In these cases, it remains unknown whether the curve will progress or remain stable. METHODS: Adolescent and juvenile idiopathic scoliosis patients in a multicenter registry with ≥2 year-follow-up after VBT were reviewed. Broken tethers were listed as postoperative complications and identified by increased screw divergence of >5° on serial radiographs. Revision procedures and curve magnitude at subsequent visits were recorded. RESULTS: Of 186 patients who qualified for inclusion, 84 (45.2%) patients with tether breakage were identified with a mean age at VBT of 12.4±1.4 years and mean curve magnitude at index procedure of 51.8°±8.1°. Tether breakage occurred at a mean of 30.3±11.8 months and mean curve of 33.9°±13.2°. Twelve patients (12/84, 14.5%) underwent 13 revision procedures after VBT breakage, including 6 tether revisions and 7 conversions to fusion. All tether revisions occurred within 5 months of breakage identification. No patients with curves <35° after breakage underwent revision. Revision rate was greatest in skeletally immature (Risser 0-3) patients with curves ≥35° at time of breakage (Risser 0-3: 9/17, 53% vs. Risser 4-5: 3/23, 13%, P=0.01).Curves increased by 3.1° and 3.7° in the first and second year, respectively. By two years, 15/30 (50%) progressed >5° and 8/30 (26.7%) progressed greater than 10°. Overall, 66.7% (40/60) reached a curve magnitude >35° at their latest follow-up, and 14/60 (23.3%) reached a curve magnitude greater than 45°. Skeletal maturity did not affect curve progression after tether breakage (P>0.26), but time to rupture did (P=0.048). CONCLUSION: While skeletal immaturity and curve magnitude were not independently associated with curve progression, skeletally immature patients with curves ≥35° at time of rupture are most likely to undergo additional surgery. Most patients can expect progression at least 5° in the first two years after tether breakage, though longer-term behavior remains unknown. LEVEL OF EVIDENCE: III.

Growth modulation response in vertebral body tethering depends primarily on magnitude of concave vertebral body growth.

PURPOSE: There is variability in clinical outcomes with vertebral body tethering (VBT) partly due to a limited understanding of the growth modulation (GM) response. We used the largest sample of patients with 3D spine reconstructions to characterize the vertebra and disc morphologic changes that accompany growth modulation during the first two years following VBT. METHODS: A multicenter registry was used to identify idiopathic scoliosis patients who underwent VBT with 2 years of follow-up. Calibrated biplanar X-rays obtained at longitudinal timepoints underwent 3D reconstruction to obtain precision morphological measurements. GM was defined as change in instrumented coronal angulation from post-op to 2-years. RESULTS: Fifty patients (mean age: 12.5 ± 1.3yrs) were analyzed over a mean of 27.7 months. GM was positively correlated with concave vertebra height growth (r = 0.57, p < 0.001), 3D spine length growth (r = 0.36, p = 0.008), and decreased convex disc height (r = - 0.42, p = 0.002). High modulators (patients experiencing GM > 10°) experienced an additional 1.6 mm (229% increase) of mean concave vertebra growth during study period compared to the Poor Modulators (GM < - 10°) group, (2.3 vs. 0.7 mm, p = 0.039), while convex vertebra height growth was similar (1.3 vs. 1.4 mm, p = 0.91). CONCLUSION: When successful, VBT enables asymmetric vertebra body growth, leading to continued postoperative coronal angulation correction (GM). A strong GM response is correlated with concave vertebral body height growth and overall instrumented spine growth. A poor GM response is associated with an increase in convex disc height (suspected tether rupture). Future studies will investigate the patient and technique-specific factors that influence increased growth remodeling.

Delayed hemothorax after anterior vertebral body tethering in adolescent idiopathic scoliosis: a case report.

PURPOSE: The aim of this case report is to report that delayed hemothorax is possible after anterior vertebral body tethering (aVBT) and to illustrate the course of treatment. METHODS: We present a 15-year-old boy with adolescent idiopathic scoliosis who underwent an anterior thoracoscopic assisted vertebral body tethering who developed a massive right-sided hemothorax 12 days post-operatively. A chest tube was placed to drain the hemothorax and later required embolectomy with tissue plasminogen activator (TPA) to drain the retained hemothorax. RESULTS: At 1 month follow up post discharge the patient was asymptomatic, and radiograph did not demonstrate evidence of residual hemothorax and scoliosis. We have followed this patient for 5 years postoperative and he continues to do well clinically and radiographically. CONCLUSIONS: Pulmonary complications are a known drawback of anterior thoracoscopic spinal instrumentation. Delayed hemothorax is possible after aVBT. In the case of a retained hemothorax, chest tube treatment with TPA is a safe and effective method of embolectomy.

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.

Differential vertebral body growth is maintained after vertebral body tethering surgery for idiopathic scoliosis: 4-year follow-up on 888 peri-apical vertebrae and 592 intervertebral discs.

PURPOSE: To radiographically evaluate if vertebral body tethering (VBT) can maintain differential peri-apical vertebral growth at medium-term follow-up of 4 years. METHODS: A prospective, international, multicenter database was queried to identify idiopathic scoliosis patients treated with thoracic VBT. Concave vs. convex vertebral body height, vertebral wedging, and disc wedging of the 3 peri-apical vertebrae were measured by two independent observers at 5 timepoints (pre-operative to 4-year follow-up). RESULTS: 65 skeletally immature patients (60 female, mean 12.8 years old, 21 with open triradiate cartilages) met inclusion criteria. Mean pre-operative maximum scoliosis of 50 ± 8° decreased significantly post-operatively to 27 ± 9° (p < 0.001), which remained stable at 4-year follow-up 30 ± 17° (p = 0.38 vs. post-operative). Mean instrumented scoliosis was 21 ± 14° at 4-year follow-up, which was significantly different than 4-year maximum scoliosis (p < 0.001). Mean pre-operative kyphosis of 30 ± 12° did not significantly change post-operatively (p = 1.0) and remained stable at 4-year follow-up (35 ± 18°; p = 0.05). Mean individual convex vertebral height increased from 17.7 ± 1.9 mm to 19.8 ± 1.5 mm (p < 0.001), while mean individual concave height increased from 14.8 ± 1.9 mm to 17.6 ± 1.6 mm (p < 0.001). Summing the peri-apical heights, the difference in height from pre-operative to 4-year follow-up was greater on the concave (8.3 ± 4.7 mm) than on the convex side (6.2 ± 4.7 mm) (p < 0.001). Mean individual vertebral wedging decreased from 6 ± 2° at pre-operative to 4 ± 2° at 4-year follow-up (p < 0.001). Mean total vertebral and disc wedging started at 29 ± 7° pre-operatively, decreased to 16 ± 6° at post-operative (p < 0.001), then further decreased to 14 ± 8° at 4-year follow-up (p < 0.001). Patients with open triradiate cartilages at the time of surgery had a larger height change over the 4 years compared to those with closed triradiate cartilages (p < 0.001). CONCLUSION: Patients with idiopathic scoliosis treated with VBT demonstrated differential vertebral growth which was maintained at minimum 4-year follow-up. This effect was more pronounced in patients whose triradiate cartilages were open at the time of surgery. LEVEL OF EVIDENCE: III.

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.

Do Caregivers and Patients With Early-Onset Scoliosis Share the Same Perspective on Health-Related Quality of Life? A Comparison of 24-item Early-Onset Scoliosis Questionnaire and 22-item Scoliosis Research Society Questionnaire Scores.

OBJECTIVE: The 24-item Early-Onset Scoliosis Questionnaire (EOSQ-24) is validated in patients with early onset scoliosis (EOS) aged 0 to 18 years and the 22-item Scoliosis Research Society (SRS-22) questionnaire is validated in idiopathic scoliosis patients 10 years and older. EOSQ-24 is completed by the caregiver and SRS-22 is completed by the patient. A prior study comparing patient-reported outcome measures completed by older pediatric patients and their parents showed a low level of agreement. Our purpose was to compare EOSQ-24 and SRS-22 scores completed at the same time point and at subsequent time points, in patients aged 5 to 18 years with idiopathic or congenital EOS without developmental delay. METHODS: This was a multicenter retrospective study. We identified pairs of EOSQ-24 and SRS-22 completed on the same day or within 6 months. Some patients had multiple pairs of surveys over time. EOSQ-24 and SRS-22 questions were matched and domain scores for Pain, Function, Mental Health, and Satisfaction were compared. Patients with a change in treatment between surveys were excluded. Pearson correlation coefficients ( r ) were used to compare domain scores, with r ≥0.7 indicating a strong relationship. RESULTS: There were 228 patient-caregiver dyads who completed 411 pairs of EOSQ-24 and SRS-22 on the same day. A strong correlation was found only for the Pain domain ( r =0.77). Function, Mental Health, and Satisfaction domains had positive but not strong correlations ( r = 0.58, r = 0.50, r = 0.41, respectively). Subanalysis based on age also showed a strong correlation only for Pain. There were 76 patient-caregiver dyads who completed 134 pairs of surveys with SRS-22 completed within 6 months after an EOSQ-24. All domains demonstrated a positive but not strong correlation, with Pain showing the highest correlation ( r = 0.64). CONCLUSIONS: EOSQ-24 and SRS-22 had a strong correlation only for Pain when completed at the same time point. EOSQ-24 and SRS-22 completed within 6 months lacked a strong correlation for all domains. Our findings suggest that parents and children with EOS may not share the same perspective on their health. Self-reported questionnaires should be used when possible to assess health-related quality of life in older children and adolescents with EOS who are developmentally neurotypical. LEVEL OF EVIDENCE: Level III-diagnostic.

Does radiographic calibration affect linear radiographic measurements in a large pediatric spine registry?

PURPOSE: Large registries are increasingly at the forefront of modern pediatric spine research, with manual, centralized, trained radiographic measurement serving as the gold standard for spine research. However, there is limited data regarding the reliability of registry measurements which may be subject to differences in radiographic calibration. We undertook this study to evaluate reliability of T1-T12 height, L1-S1 height, and coronal balance measurements for a large registry of early onset scoliosis patients. METHODS: Three trained technicians from the Pediatric Spine Study Group measured 43 radiographs for T1-T12, L1-S1, and coronal balance using 3 different calibration techniques. All radiographs were AP views of patients with magnetically controlled growing rods with known diameters. The calibration techniques used a pre-export manually drawn line, a digital automatically generated computerized marker, and the diameter of a magnetically controlled growing rod. The intraclass correlation coefficient (ICC) was calculated to determine reliability. RESULTS: 1161 measurements were performed. For each of the three raters, coronal balance, T1-T12 height and L1-S1 height had excellent agreement regardless of the calibration technique (alpha 0.93-1.0). Among the parameters, coronal balance had the worst inter-rater reliability, whereas there was excellent interrater reliability regarding T1-T12 height and L1-S1 height (alpha 0.91-0.99). CONCLUSION: There was excellent agreement among reviewers and between the 3 different calibration techniques. While calibration using rod diameter served as the gold standard, this data shows that other standard calibration methods were adequate and achieved excellent reliability for registry radiographs.

A low-dose biplanar X-ray imager has RSA level precision in total knee arthroplasty.

BACKGROUND AND PURPOSE: The low radiation biplanar X-ray imager (EOS imaging, Paris, France) scans patients in a weight-bearing position, provides calibrated images, and limits radiation, an asset for serial radiostereometric analysis (RSA) studies. RSA in vivo precision values have not been published for this type of imaging system, thus the goal of this study was to assess the precision of RSA in vivo utilizing a low radiation biplanar imager. PATIENTS AND METHODS: At a mean of 5 years post-surgery (range 1.4-7.5 years), 15 total knee arthroplasty (TKA) participants (mean age 67 years at the time of imaging, 12 female, 3 male) with RSA markers implanted during index surgery were scanned twice at the same visit in the EOS imager. Precision of marker-based analysis was calculated by comparing the position of the implant relative to the underlying bone between the 2 examinations. RESULTS: The 95% limit of precision was 0.11, 0.04, and 0.15 mm along the x, y, and z axes, respectively and 0.15°, 0.20°, and 0.14° around the same axes. CONCLUSION: This precision study has shown an in vivo RSA precision of ≤ 0.15 mm and ≤ 0.20°, well within published uniplanar values for conventional arthroplasty RSA, with the added benefit of weight-bearing imaging, a lower radiation dose, and without the need for a reference object during the scan.

Growth friendly surgeries increase 3D true spine length at two-years post-operative.

PURPOSE: Traditional coronal-plane vertical spine height measurements, such as T1-T12 and T1-S1 spine height, are influenced by 3-dimensional spinal deformity. Therefore, they are unreliable indicators of true spine growth. The novel 3D true spine length (3D-TSL) technique assesses spine growth regardless of the presence of 3D spinal deformity. This study evaluates the effect of growth friendly surgery on spine growth using the 3D-TSL technique at two years follow-up. METHODS: Radiographs of early onset scoliosis (EOS) participants undergoing growth friendly surgery at a single institution were evaluated at pre-index, post-index, and at 2-year follow-up. Scoliosis, kyphosis, traditional coronal height and 3D-TSL were measured. RESULTS: Twenty-four EOS patients (14 female) with a mean age of 6.3 years were included. Scoliosis improved from 77.8 ± 18.7° pre-index to 56.0 ± 17.8° post-index (p < 0.001); but increased at 2 years to 65.9 ± 20.1° (p < 0.05). Kyphosis improved from 56.0 ± 20.7° pre-index to 39.3 ± 13.8° post-index (p < 0.001); and increased again at 2 years to 48.6 ± 16.4° (p < 0.05). Traditional T1-S1 height increased from pre-index to post-index, to 2-year follow-up (245.5 ± 37.2 mm to 275.8 ± 42.7 mm; p < 0.001, to 288.0 ± 41.7 mm; p = 0.005). As expected, T1-S1 3D-TSL did not change from pre to immediately post-index (305.6 ± 43.9 mm vs 306.5 ± 44.0 mm); there was a significant change from post-index to 2-year follow-up (334.1 ± 48.0 mm; p < 0.001). CONCLUSIONS: Out of plane changes in scoliosis and kyphosis over time justify the use of the 3D-TSL for this cohort of patients. There was no significant change in 3D-TSL from pre-index to post-operatively; however, during the growth phase of treatment 3D-TSL increased significantly by 27.6 mm.

Concave and convex growth do not differ over tethered vertebral segments, even with open tri-radiate cartilage.

PURPOSE: To assess the following hypotheses related to vertebral body tethering (VBT): 1. VBT is associated with asymmetric (concave > convex) increases in height over the instrumented vertebra. 2. The instrumented Cobb angle improves following VBT surgery with growth. METHODS: This is a retrospective case series of pediatric patients from a multicenter scoliosis registry treated with VBT between 2013 to 2021. INCLUSION CRITERIA: patients with standing radiographs at < 4 months and ≥ 2 years after surgery. Distances between the superior endplate of the UIV and the inferior endplate of the LIV were measured at the concave corner, mid-point, and convex corner of the endplates. The UIV-LIV angle was recorded. Subgroup analyses included comparing different Risser scores and tri-radiate cartilage (TRC) closed versus open using student t-tests. RESULTS: 83 patients met inclusion criteria (92% female; age at time of surgery 12.5 ± 1.4 years) with mean follow-up time of 3.8 ± 1.4 years. Risser scores at surgery were: 0 (n = 33), 1 (n = 12), 2 (n = 10), 3 (n = 11), 4 (n = 12), and 5 (n = 5). Of the 33 Risser 0 patients, 17 had an open TRC, 16 had a closed TRC. The UIV-LIV distance at concave, middle, and convex points significantly increased from immediate post-op to final-follow-up for Risser 0 patients, but not for Risser 1-5 patients. Increases in UIV-LIV distance were not significantly different between concave, middle, and convex points for all groups. There was no significant improvement or worsening in UIV-LIV angle for any group. CONCLUSION: At a mean of 3.8 years following VBT, 33 Risser 0 patients demonstrated significant growth in the instrumented segment, though there was no difference between concave or convex growth, even for patients with open TRC.

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.

Low radius of curvature growth-friendly rib-based implants increase the risk of developing clinically significant proximal junctional kyphosis.

BACKGROUND: Clinically significant proximal junctional kyphosis (PJK) occurs in 20% of children with scoliosis treated with posterior distraction-based growth-friendly surgery. In an effort to identify modifiable risk factors, it has been theorized biomechanically that low radius of curvature (ROC) implants (i.e., more curved rods) may increase post-operative thoracic kyphosis, and thus may pose a higher risk of developing PJK. We sought to test the hypothesis that early onset scoliosis (EOS) patients treated with low ROC distraction-based implants will have a greater risk of developing clinically significant PJK as compared to those treated with high ROC (straighter) implants. METHODS: We conducted a retrospective review of prospectively collected data obtained from a multi-centre EOS database on children treated with rib-based distraction with a minimum 2-year follow-up. Variables of interest included: implant ROC at index (220 mm or 500 mm), participant age, pre-operative scoliosis, pre-operative kyphosis, and scoliosis etiology. PJK was defined as clinically significant if revision surgery with a superior extension of the upper instrumented vertebrae was performed. RESULTS: In 148 participants with scoliosis, there was a higher risk of clinically significant PJK with low ROC (more curved) rods (OR: 2.6 (95% CI 1.09-5.99), χ2 (1, n = 148) = 4.8, p = 0.03). Participants had a mean pre-operative age of 5.3 years (4.6y 220 mm vs 6.2y 500 mm, p = 0.002). A logistic regression model was created with age as a confounding variable, but it was determined to be not significant (p = 0.6). Scoliosis etiologies included 52 neuromuscular, 52 congenital, 27 idiopathic, 17 syndromic with no significant differences in PJK risk between etiologies (p = 0.07). Overall, participants had pre-op scoliosis of 69° (67° 220 mm vs 72° 500 mm, p = 0.2), and kyphosis of 48° (45° 220 mm vs 51° 500 mm, p = 0.1). The change in thoracic kyphosis pre-operatively to final follow-up (mean 4.0 ± 0.2 years) was higher in participants treated with 220 mm implants compared to 500 mm implants (220 mm: 7.5 ± 2.6° vs 500 mm: - 4.0 ± 3.0°, p = 0.004). CONCLUSIONS: Use of low ROC (more curved) posterior distraction implants is associated with a significantly greater increase in thoracic kyphosis which likely led to a higher risk of developing clinically significant PJK in participants with EOS. LEVEL OF EVIDENCE: Level III - retrospective comparative study.

Vertebral body tethering for non-idiopathic scoliosis: initial results from a multicenter retrospective study.

PURPOSE: Vertebral body tethering (VBT) has been described for patients with idiopathic scoliosis. Results of the technique for non-idiopathic scoliosis have not yet been reported. METHODS: An international multicenter registry was retrospectively queried for non-idiopathic scoliosis patients who underwent VBT with minimum 2-year follow-up. Success at 2 years was defined as Cobb angle < 35 degrees and no fusion surgery. RESULTS: Of the 251 patients treated with VBT, 20 had non-idiopathic scoliosis and minimum 2-year follow-up. Mean age at surgery was 12.4 years (range 10 to 17 years). Mean major Cobb angle at enrollment was 56 degrees. Of those, 18 patients had a major thoracic curve and two had a major lumbar curve. Of the 20 patients, nine met criteria for success (45%). Eight of the 20 patients had poor outcomes (four fusions, four with curve > 50 degrees). Success was associated with smaller preoperative Cobb angle (50 vs. 62 degrees, p = 0.01) and smaller Cobb angle on initial postop imaging (28 degrees vs. 46 degrees, p = 0.0007). All patients with Cobb angle < 35 degrees on 1st postop imaging had a successful result, with the exception of one patient who overcorrected and required fusion. Syndromic vs. neuromuscular patients had a higher likelihood of success (5 of 7, 71%, 2 of 10, 20%, p = 0.03). CONCLUSION: Selected non-idiopathic scoliosis can be successfully treated with VBT, but failure rates are high and were associated with large curves, inadequate intraoperative correction and neuromuscular diagnosis. Achieving a Cobb angle less than 35 degrees on 1st standing radiograph was associated with a successful outcome which was achieved in 45% of patients. LEVEL OF EVIDENCE: Level IV (retrospective review study).

Effects of distraction-based distal fixation on pelvic parameter development in early onset scoliosis.

PURPOSE: Prior studies have suggested that distraction-based treatment for early onset scoliosis (EOS) may impede the natural development of the sagittal spinal alignment and pelvic parameters. However, to date no study has investigated the effect of distal fixation on pelvic development. METHODS: Ambulatory children with EOS undergoing index distraction-based treatment with distal fixation below T11 were retrospectively reviewed. Patients with distal fixation to the pelvis were identified and compared to children with Spine-based fixation at T12-L5. Radiographic measurements were performed for coronal and sagittal alignment in addition to pelvic parameters (pelvic incidence (PI), pelvic tilt (PT), and sacral slope (SS) and compared at initial presentation, first erect radiograph, and at 2 years following instrumentation. RESULTS: 33 ambulatory children were identified with a minimum of 2-year follow-up (25 female, average 6.59 ± 2.6 years), with 33% (N = 11) instrumented to the pelvis (54.4% female, average 4.42 ± 2.2 years, initial Cobb 76.1°). Children in the pelvis cohort were significantly younger at treatment initiation (P < 0.001). There was no significant difference in PI at the study time periods, however, there was a significant change in PI between presentation and 2-year follow-up with the pelvic fixation demonstrating a mean 12.3° decrease in PI vs a 3.8° increase in the spine-based cohort (P = 0.027). DISCUSSION: Distal fixation to the pelvis in ambulatory children with EOS treated with growth-friendly instrumentation was associated with a mean decrease in PI of 12.3° that developed over the 2-year treatment duration. Further research is needed to investigate the long-term implications of these findings on pelvic and spinal development.

Reliability of radiographic assessment of growth modulation from anterior vertebral body tethering surgery in pediatric scoliosis.

PURPOSE: To assess the reliability of vertebral height and angular measurements for anterior vertebral body tethering (AVBT). METHODS: Eight observers measured PA radiographs of 15 idiopathic scoliosis patients treated with AVBT, pre-operative and 4-year follow-up. Vertebral wedging, disc wedging, convex vertebral body heights, and concave vertebral body heights of the 3 apical vertebrae were measured. For each observer, there were a total of 90 measurements for vertebral body height and 75 measurements for all wedging types At least 14 days elapsed between first and second round measurements. RESULTS: From the pre-operative to the 4-year follow-up time-point, the total wedging angle over the 3 peri-apical levels fell from 30 ± 7° to 16 ± 6° (p < 0.001) and the difference between the convex and concave vertebral heights decreased from 9 ± 4 to 6 ± 3 mm (p < 0.001). Interobserver agreement for pre-operative vertebral body heights was good [ICC = 0.80; 95% CI (0.74-0.85)]. At 4-year follow-up there was a moderate agreement [ICC = 0.67 (0.59-0.74)]. There was a poor interobserver agreement for pre-operative wedging angle measurements [ICC = 0.41 (0.32-0.52)] and 4-year follow-up [ICC = 0.45 (0.36-0.56)]. The Limits of Agreement with the Mean (LOAM) for pre-op heights was ± 2.4 mm, similar to the follow-up ± 2.6 mm. When raters are averaged in random groups of two the agreement limits decrease to ± 1.8 mm pre-op and ± 1.6 mm at follow-up. Similarly for wedging angles, LOAM values among the 8 observers of ± 4.6° pre-op and ± 4.2° dropped to ± 2.7° for both pre-op and follow-up when random groups of two raters were averaged together. Intraobserver agreement ranged from good to excellent per individual (ICC = 0.84-0.94) for pre-operative vertebral body heights, but this decreased at 4-year follow-up (ICC = 0.52-0.88). Intraobserver agreement was low overall for wedging (pre-operative ICC = 0.41-0.71; 4-year follow-up ICC = 0.41-0.76). CONCLUSION: Based on 8 individual observers, interobserver agreement ranged from good (pre-operative vertebral body heights) to moderate (4-year follow-up vertebral body heights) to poor (all wedging angles). To improve the reliability of the measurement of wedging angles, we recommend averaging the measurements of at least two observers.

Venous Thromboembolism Prophylaxis Use by Pediatric Orthopedic Surgeons in Canada for the Pediatric Orthopedic Surgical Population.

Introduction A novel pediatric venous thromboembolism (VTE) screening tool was implemented in 2016 at the Izaak Walton Killam (IWK) Health Centre, which safely reduced the use of thromboprophylaxis by 47.9% with no increase in VTE in the pediatric orthopedic surgical population (POSP). There is presently no data on the current practices or protocols for VTE prophylaxis for POSP in Canada. The present survey was designed to assess current practices regarding VTE prophylaxis for POSP in Canada. Methods After research ethics board (REB) approval, a 22-question survey was administered electronically to all Canadian Pediatric Orthopedic Group (CPOG) members. The survey contained questions on respondent demographics and background, current VTE prophylaxis practices and experiences including indications for prophylaxis, the existence of VTE protocols, and interest in utilizing VTE protocols. Descriptive statistical analyses and analysis of variance (ANOVA) were completed on the survey responses. Results Of the 100 CPOG members, 49 (49%) responded. Most respondents (51%, n=25/49) practice in Central Canada, 39% (n=19/49) practice in Western Canadian provinces, and a smaller portion practice in Atlantic Canada (10%, n=5/49). Of the respondents, 43% (n=21/49) indicated that they use pharmacologic VTE prophylaxis in their practice, and 93% (n=27/29) stated that specific risk factors are indications of initiating pharmacologic VTE prophylaxis. Additionally, 57% (n=16/28) did not have a defined protocol for VTE prophylaxis, and 18% (n=5/28) were uncertain if they do. Of the respondents, 85% (n=22/26) were open to utilizing a VTE prophylaxis screening tool, and 12% (n=3/26) were uncertain if they would be. Conclusion This study has demonstrated that a uniform protocol for VTE prophylaxis does not exist in most Canadian centers, despite its need. There is nationwide interest in adopting a perioperative VTE prophylaxis screening tool to optimize pharmacologic thromboprophylaxis use in POSP. The goal of future research is the national implementation and standardization of such a screening tool through collaboration in a multicenter study.

Predicting Health-Related Quality of Life Outcomes Following Major Scoliosis Surgery in Adolescents: A Latent Class Growth Analysis.

STUDY DESIGN: Prospective cohort study. OBJECTIVES: To identify patient trajectories of recovery defined by change in health-related quality of life (HRQOL) following surgery for adolescent idiopathic scoliosis (AIS). To explore possible predictors of trajectory membership. METHODS: Adolescent patients scheduled to undergo spinal fusion for AIS were enrolled in the Post-Operative Recovery following Spinal Correction: Home Experience (PORSCHE) study. Responses to the Pediatric Quality of Life Inventory-version 4 (PedsQL-4.0) were collected prior to surgery and 4 to 6 weeks, 3, 6, and 12 months post-operatively. Latent class growth analyses identified patient subgroups based on their unique trajectories of physical health (PH) and psychosocial health (PSH) outcomes using the PedsQL-4.0 subscale scores. Predictors included demographic, clinical, and psychosocial factors. RESULTS: Data from up to 190 patients were included (87.4% female; mean±SD age = 14.6 ± 1.9 years). Three trajectory subgroups were identified for PH and 4 trajectories were found for PSH, with a majority of patients scoring within the established range of healthy adolescents 12 months post-surgery. Increased child and parent pain catastrophizing, child trait anxiety and previous hospitalizations were associated with poorer PH outcomes, whereas increased child and parent pain catastrophizing, child state and trait anxiety, and parent state and trait anxiety were associated with poorer PSH trajectories. CONCLUSIONS: The PH and PSH trajectories identified in this study and the factors associated with their membership may inform surgical decision-making for AIS while facilitating patient and family counselling regarding peri-operative recovery and expectations.