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Purpose: Two non-fusion devices for adolescent idiopathic scoliosis (AIS) received HDE approval for clinical use in 2019: posterior dynamic distraction device (PDDD) and vertebral body tethering system (VBT). Although indications are similar, there is no comparative study of these devices. We hypothesize that curve correction will be comparable, but PDDD will have better perioperative metrics., Methods: AIS PDDD patients were prospectively enrolled in this matched multicenter study. Inclusion criteria were Lenke 1 or 5 curves, preoperative curves 35°-60°, correction to ≤30° on bending radiographs, and kyphosis <55°. Patients were matched by age, sex, Risser, curve type and curve magnitude to a single-center cohort of VBT patients. Results were compared at 2 years., Results: 20 PDDD patients were matched to 20 VBT patients. Blood loss was higher in the VBT cohort (88 vs. 36 ml, p < 0.001). Operative time and postoperative length of stay were longer in the VBT cohort, 177 vs. 115 min (p < 0.001) (2.9 vs. 1.2 days, p < 0.001). Postoperative curve measurement and correction at 6 months were better in the PDDD cohort (15° vs. 24°, p < 0.001; 68% vs. 50%, p < 0.001). At 1-year, PDDD patients had improved Cobb angles (14° vs. 21°, p = 0.001). At 2 years, a correction was improved in the PDDD cohort, with a curve measurement of 17° for PDDD and 22° for VBT (p = 0.043). At the latest follow-up, 3 PDDD patients and 1 VBT patient underwent revision surgery., Conclusion: Early results show PDDD demonstrates better index correction, reduced operative time, less blood loss, and shorter length of stay but higher rates of revision compared to a matched cohort of VBT patients at two-year follow-up., Level of Evidence: Level II, prospective cohort matched comparative study., (© 2024. The Author(s), under exclusive licence to Scoliosis Research Society.)

Purpose: Our purpose was to determine associations between body mass index (BMI) category and outcomes of vertebral body tethering (VBT), a non-fusion treatment for adolescent idiopathic scoliosis (AIS) and juvenile idiopathic scoliosis (JIS)., Methods: Using a multicenter database, we identified patients with AIS or JIS who underwent VBT from 2012 to 2018 and had minimum 2-year follow-up (median, 3.0 [interquartile range 2.2, 3.8]). BMI percentiles were used to classify patients as overweight (≥ 85th percentile) or non-overweight (< 85th percentile). Univariate and multivariate regressions assessed associations between complication rates and curve correction between groups, controlling for sex, triradiate cartilage closure, and preoperative curve magnitude., Results: Of 271 patients, 48 (18%) were overweight. Complication rates did not differ between groups. Factors associated with less correction from preoperative to first postoperative-erect imaging were overweight (β = - 10, p < 0.001), male sex (β = - 8.8 p < 0.01), closed triradiate cartilage (β = 6.0, p = 0.01), and smaller preoperative curve (β = 0.3, p < 0.01). Factors associated with a larger curve at latest follow-up were overweight (β = 4.0, p = 0.02) and larger preoperative curve (β = 0.5, p < 0.001), but tether breakage did not differ between groups (p = 0.31)., Conclusion: In patients who were overweight, VBT was associated with less curve correction at first erect imaging and larger final curve. However, complications and curve correction during the modulation phase were not different from those of non-overweight patients. These findings suggest that surgeons should expect less correction with VBT in patients who are overweight but similar correction over time., Level of Evidence: Prognostic, Level III., (© 2024. The Author(s), under exclusive licence to Scoliosis Research Society.)

Purpose: Posterior spinal fusion (PSF) is the current gold standard in surgical treatment for adolescent idiopathic scoliosis. Vertebral body tethering (VBT) is a fusionless alternative. Shoulder balance is an important metric for outcomes and patient satisfaction. Here we compare shoulder balance outcomes between PSF and VBT., Methods: In this retrospective review, the pre-operative and post-operative absolute radiographic shoulder height (|RSH|) of 45 PSF patients were compared to 46 VBT patients. Mean values were compared and then collapsed into discrete groups (|RSH| GROUP) and compared. Patients were propensity score matched. Regression models based on pretest-posttest designs were used to compare procedure type on post-operative outcomes., Results: Pre-operatively there were no differences in |RSH| between PSF and VBT, however, at latest post-operative follow-up PSF maintained a larger |RSH| imbalance compared to VBT (0.91 cm vs 0.63 cm, p = 0.021). In an ANCOVA regression, PSF was associated with a larger |RSH| imbalance compared to VBT, F(1, 88) = 5.76, p = 0.019. An ordinal logistic regression found that the odds ratio of being in a worse |RSH| GROUP for PSF vs VBT is 2.788 (95% CI = 1.099 to 7.075), a statistically significant effect χ 2 (1) = 4.658, p = 0.031. Results were similar in subgroup analyses of Lenke 1 and Lenke 2 patients, though to less statistical significance., Conclusion: While PSF was found to be associated with worse |RSH| outcomes, the actual numbers (2-3 mm) are unlikely to be clinically meaningful. Thus, in this analysis, VBT can be said to show comparable shoulder balance outcomes to PSF., (© 2024. The Author(s), under exclusive licence to Scoliosis Research Society.)

Purpose: Vertebral body tethering (VBT) is a non-fusion alternative to posterior spinal fusion (PSF). There have been few reports on VBT of two curvatures. We aim to compare the radiographic outcomes between VBT and PSF in patients with double curvatures in which both curves were instrumented., Methods: 29 AIS patients matched by Lenke, age (± 2 years), triradiate cartilage closure status, major Cobb angle (± 8°), and T5-T12 kyphosis (± 10°). Variables were compared using Wilcoxon rank-sum tests, Student's t tests, and chi-Square. Clinical success was defined as major curve < 35°., Results: Group baseline demographics were similar. Major thoracic (T) curve types had significantly better major (VBT 51.5 ± 7.9° to 31.6 ± 12.0° [40%] vs. PSF 54.3 ± 7.4° to 17.4 ± 6.5° [68%]; p = 0.0002) and secondary curve correction in the PSF group. 71% of major T VBT patients were clinically successful versus 100% of PSF. Major thoracolumbar (TL) curve types experienced comparable major (VBT 52.3 ± 7.0° to 18.3 ± 11.4° (65%) vs. PSF 53.0 ± 5.2° to 23.8 ± 10.9° (56%); p = 0.2397) and secondary curve correction. 92% of major TL VBT patients were clinically successful versus 75% in the PSF group. There was no difference in T5-12 kyphosis or lumbar lordosis between groups for any curve type. There were 4 patients (13.8%) with major complications in the VBT group compared to 0 (0%) in the PSF., Conclusion: Patients with double major AIS who underwent VBT with major T curve types had less correction than PSF; however, those with major TL curves experienced similar radiographic outcomes regardless of procedure. Complications were greater for VBT., (© 2024. The Author(s), under exclusive licence to Scoliosis Research Society.)

Case: An 11-year-old girl with pectus excavatum presented with an acute airway obstruction and persistent pulmonary compromise after vertebral body tethering (VBT). The anterior instrumentation was occluding her right basilar bronchus, resulting in hyperinflation. Removal of the instrumentation reversed the hyperinflation., Conclusion: This case illustrates the difficulty of performing VBT in a small patient with severe scoliosis and significant asymmetric pectus excavatum. We recommend using low-profile instrumentation and ensuring the trajectory of the instrumentation is anterior to the rib head and parallel to the articular facets., Competing Interests: Disclosure: The Disclosure of Potential Conflicts of Interest forms are provided with the online version of the article (http://links.lww.com/JBJSCC/C218)., (Copyright © 2023 by The Journal of Bone and Joint Surgery, Incorporated.)

Purpose: Since the introduction of vertebral body tethering (VBT) for adolescent idiopathic scoliosis (AIS), a variety of post-operative chest drainage systems have been utilized. Most surgeons use formal chest tubes with a Pleur-evac, while others use smaller bulb suction drains (e.g., Blake drain). In addition, some centers utilize pleural closure. This multicenter study evaluates whether drain type or pleural closure impact perioperative and 90 day complication rates., Methods: A retrospective review was conducted from three institutions with established VBT programs. All preoperative, perioperative and 90 day postoperative data were analyzed to determine differences in outcomes between three cohorts: standard chest tube (SCT), standard chest tube with pleural closure (SCTPC) and 10 French Bulb drain (BD)., Results: 104 patients were identified for the study. 57 SCT, 25 SCTPC and 22 BD. All data are listed in order: SCT, SCTPC, BD. Length of stay (3.7, 4.3, 3.0 days) was less in the BD group (p = 0.009); post-operative drainage (460, 761, 485 cc) was less in the SCT and BD groups (p < 0.001); intra-operative estimated blood loss (EBL) 146, 382, 64 cc was less in the BD group (p < 0.001). No significant difference in number of days (3.2, 3.2, and 2.8 days) drainage was in place, groups (p = 0.311). Complication profile was similar with 2 chest tube reinsertions in the SCT and one hemothorax that resolved spontaneously in BD group., Conclusions: In this series of 104 patients, SCT, SCTPC and BD all had a similar safety profile. All three methods were safe and effective in managing post-operative chest drainage after thoracic VBT. In the series, BD group had significantly shorter LOS than both groups that used chest tubes., Level of Evidence: Level III, Retrospective cohort study., (© 2022. The Author(s), under exclusive licence to Scoliosis Research Society.)

Purpose: This study was undertaken to collect baseline growth parameters in children with achondroplasia who might enroll in interventional trials of vosoritide, and to establish a historical control., Methods: In this prospective, observational study, participants (≤17 years) underwent a detailed medical history and physical examination and were followed every 3 months until they finished participating in the study by enrolling in an interventional trial or withdrawing., Results: A total of 363 children were enrolled (28 centers, 8 countries). Mean (SD) follow up was 20.4 (15.0) months. In participants <1 year, mean annualized growth velocity (AGV) was 11.6 cm/year for girls and 14.6 cm/year for boys. By age 1 year, mean AGV decreased to 7.4 cm/year in girls and 7.1 cm/year in boys. By age 10 years, mean AGV decreased to 3.6 cm/year for both sexes. Mean height z-score in participants <1 year was -2.5 for girls and -3.2 for boys and decreased up to the age 5 years (-5.3 for girls; -4.6 for boys). Girls and boys had a disproportionate upper-to-lower body segment ratio. Mean ratio was highest in participants aged <1 year (2.9 for girls; 2.8 for boys) and decreased gradually to approximately 2 in both sexes from 4 years of age onward., Conclusion: This study represents one of the largest datasets of prospectively collected medical and longitudinal growth data in children with achondroplasia. It serves as a robust historical control to measure therapeutic interventions against and to further delineate the natural history of this condition., Competing Interests: Conflict of Interest All authors were investigators in this clinical trial except for C.A., K.L., K.G., G.J., C.M., E.F., A.H.-L., and J.D., who are employees of the funder (BioMarin). R.S. L.T., F.R., K.M., have received consulting fees and grants from BioMarin. M.I. and W.R.W. have received consulting fees from BioMarin. D.B. has received grants from BioMarin. J.C. has received honoraria from Genzyme, Applied Therapeutics, and CHIESI Farmaceutici S.p.A. P.A. has received honoraria from BioMarin. P.H. and C.B. have received consulting fees, honoraria and grants from BioMarin. J.H.F. has received consulting fees from BioMarin,Therachon AG and Ascendis, and grants from BioMarin. M.B. has received consulting fees and grants from BioMarin, Ascendis, Therachon, QED, Tyra Biosciences, and Alexion Pharmaceuticals, Inc, and grants from BioMarin, Ascendis, Therachon, QED, Medlife, SOBI, and Shire. K.K.W. has received consulting fees from BioMarin, grants from BioMarin, Ultragenyx, Pfizer, and Theracon, and royalties from UptoDate.com. L.P. has received consulting fees from BioMarin, Sanofi/Genzyme, and Therachon, and grants from Sanofi/Genzyme, Takeda/Shire, Pfizer, and SOBI. The other authors declare no conflict of interests., (Copyright © 2022 The Authors. Published by Elsevier Inc. All rights reserved.)

Purpose: Achondroplasia is caused by pathogenic variants in the fibroblast growth factor receptor 3 gene that lead to impaired endochondral ossification. Vosoritide, an analog of C-type natriuretic peptide, stimulates endochondral bone growth and is in development for the treatment of achondroplasia. This phase 3 extension study was conducted to document the efficacy and safety of continuous, daily vosoritide treatment in children with achondroplasia, and the two-year results are reported., Methods: After completing at least six months of a baseline observational growth study, and 52 weeks in a double-blind, placebo-controlled study, participants were eligible to continue treatment in an open-label extension study, where all participants received vosoritide at a dose of 15.0 μg/kg/day., Results: In children randomized to vosoritide, annualized growth velocity increased from 4.26 cm/year at baseline to 5.39 cm/year at 52 weeks and 5.52 cm/year at week 104. In children who crossed over from placebo to vosoritide in the extension study, annualized growth velocity increased from 3.81 cm/year at week 52 to 5.43 cm/year at week 104. No new adverse effects of vosoritide were detected., Conclusion: Vosoritide treatment has safe and persistent growth-promoting effects in children with achondroplasia treated daily for two years., (© 2021. The Author(s).)

Background: There are no effective therapies for achondroplasia. An open-label study suggested that vosoritide administration might increase growth velocity in children with achondroplasia. This phase 3 trial was designed to further assess these preliminary findings., Methods: This randomised, double-blind, phase 3, placebo-controlled, multicentre trial compared once-daily subcutaneous administration of vosoritide with placebo in children with achondroplasia. The trial was done in hospitals at 24 sites in seven countries (Australia, Germany, Japan, Spain, Turkey, the USA, and the UK). Eligible patients had a clinical diagnosis of achondroplasia, were ambulatory, had participated for 6 months in a baseline growth study and were aged 5 to less than 18 years at enrolment. Randomisation was done by means of a voice or web-response system, stratified according to sex and Tanner stage. Participants, investigators, and trial sponsor were masked to group assignment. Participants received either vosoritide 15·0 μg/kg or placebo, as allocated, for the duration of the 52-week treatment period administered by daily subcutaneous injections in their homes by trained caregivers. The primary endpoint was change from baseline in mean annualised growth velocity at 52 weeks in treated patients as compared with controls. All randomly assigned patients were included in the efficacy analyses (n=121). All patients who received one dose of vosoritide or placebo (n=121) were included in the safety analyses. The trial is complete and is registered, with EudraCT, number, 2015-003836-11., Findings: All participants were recruited from Dec 12, 2016, to Nov 7, 2018, with 60 assigned to receive vosoritide and 61 to receive placebo. Of 124 patients screened for eligibility, 121 patients were randomly assigned, and 119 patients completed the 52-week trial. The adjusted mean difference in annualised growth velocity between patients in the vosoritide group and placebo group was 1·57 cm/year in favour of vosoritide (95% CI [1·22-1·93]; two-sided p<0·0001). A total of 119 patients had at least one adverse event; vosoritide group, 59 (98%), and placebo group, 60 (98%). None of the serious adverse events were considered to be treatment related and no deaths occurred., Interpretation: Vosoritide is an effective treatment to increase growth in children with achondroplasia. It is not known whether final adult height will be increased, or what the harms of long-term therapy might be., Funding: BioMarin Pharmaceutical., (Copyright © 2020 Elsevier Ltd. All rights reserved.)

Study Design: Computed tomographic (CT) study of thoracic spine pedicles., Objective: To analyze the usefulness of the superior articular process (SAP) as an external landmark for determining the transverse plane angulation of thoracic pedicles., Summary of Background Data: The use of thoracic pedicle screws has become commonplace. Although most authors report them to be safe, their use poses a risk to neurovascular structures. Previous studies have provided useful information regarding thoracic pedicle anatomy, but this information is difficult to apply intra-operatively. To avoid neurovascular injury, it is important to determine the correct transverse plane angulation of screw insertion., Methods: Two separate investigators reviewed thoracic spine CT scans of 53 patients, 26 years of age or younger. Measurements were taken of the angular relationship of the pedicle and the SAP of T4-T11. A 90° angle was subtended from a line parallel to the SAP with a starting point at the midpoint of the lateral half of the SAP. Measurements were then adjusted laterally for medial breeches and medially for lateral breeches, to align the trajectory down the middle of the pedicle. The degree of correction was recorded. Each investigator made 3 sets of measurements. We calculated kappa values to assess intra-observer/interobserver agreement., Results: Of the 4,008 measurements, 95.2% were contained within bone, leaving 4.8% pedicle violations. The average correction made for medial and lateral breeches was 6.3% and 6.7%, respectively. The first rater had 92.6% agreement, and an intra-observer kappa value of 0.57. The second rater had a 95.3% agreement and an intra-observer kappa value of 0.40., Conclusions: The results support the hypothesis that the SAP can be a useful external landmark for determining the transverse plane angulation of thoracic pedicle screw insertion., (Copyright © 2013 Scoliosis Research Society. Published by Elsevier Inc. All rights reserved.)

The pediatric triplane ankle fracture represents a unique spectrum of injury that does not fit neatly into the Salter-Harris classification of physeal injury. This fracture is particular to the pediatric population and often is termed a transitional injury. It is the result of the characteristic asymmetric closure of the distal tibial physis over a period of approximately 18 months. The triplane ankle fracture is a multiplanar injury with three classically described fracture fragments. It has several variations and represents 5% to 10% of pediatric intra-articular ankle injuries. The fracture typically presents in children aged 12 to 15 years; incidence is slightly higher in boys than in girls. Nondisplaced triplane fractures and extra-articular fractures can be managed with immobilization in a long leg cast. Displaced fractures are treated with open reduction and internal fixation performed through an anterolateral approach or an anteromedial approach. Intra-articular reduction to within 2 mm is required for optimal treatment of these unique pediatric ankle fractures.

Study Design: Ten cadavers were dissected to describe the cutaneous branches of the dorsal rami nerves that should be identified and protected throughout the thoracoplasty procedure., Objective: To identify the anatomic distribution of the cutaneous branches of the dorsal rami in the thoracic spine., Summary of Background Data: The last anatomic description of cutaneous branches of the dorsal rami nerves dates back to the early 1900s., Methods: Ten cadavers were dissected. Each of the branches was followed deeper into the musculature of the back. The Steel 2-incision approach, the Geissele subcutaneous approach, and the subfascial/subtrapezial approach were then carried out on each cadaver., Results: We determined the course traveled by each of these cutaneous branches of the dorsal rami. Medial branches traverse the paraspinal muscles running dorsally within a few millimeters of the midline before exiting beneath the trapezius. Lateral branches cross the top border of the inferior rib at an average of 6.8 mm from the tip of the transverse process and the lower border of the rib 27 mm from the tip of the transverse process., Conclusions: Both branches of the dorsal rami nerves are encountered during the posterior approaches used. Medial branches have the best chance for identification and preservation with the subtrapezial approach. Lateral branches can be identified and protected in each of the 3 posterior exposures.