BACKGROUND:Nonfusion techniques, such as the posterior dynamic distracting device (PDDD), for adolescent idiopathic scoliosis (AIS), aim to correct deformity and preserve motion. PDDD relies on 2 pedicle screws cranially but only a single caudal screw, a design that may predispose to implant complications. This study evaluated the role of caudal screw parameters-depth, trajectory, and diameter-on mechanical failure, revision surgery, and curve correction. METHODS:A review of AIS patients from a multicenter registry who underwent PDDD with ≥2 years of follow-up was performed. Radiographic measures included caudal screw depth, rod-to-caudal screw angle, and caudal screw-to-upper endplate angle postoperatively and at final follow-up or before revision. RESULTS:A total of 155 patients (mean age 14.4 y, range 10 to 19 y) were included with a mean f/u of 2.3 years. Initial coronal deformity was 46 degrees, which improved to 21 degrees at final f/u. Construct breakage occurred in 17% and overall mechanical failure in 27%. Revisions for mechanical failure occurred in 14%. Revisions, breakage, and mechanical failure were all correlated with more convergent, negative, initial screw-toupper endplate angle (P=0.025, P=0.003, and P<0.001, respectively). Mechanical failure correlated with lower final caudal screw depth (P=0.025), lower initial actuator-to-caudal screw angle (P=0.010), and initial and final convergent screw-to-upper endplate angulation (P<0.001 and P=0.010, respectively). Multivariable logistic regression identified initial caudal sagittal angle (OR: 0.893; P=0.003) and Lenke curve type (OR: 0.446; P=0.049) as independent predictors of mechanical failure, with the final model demonstrating strong predictive capacity (AUC=0.755). CONCLUSION:PDDD achieved meaningful curve correction, but with notable mechanical failure rates. Convergent caudal screw angulation, but not screw depth or diameter, was associated with construct breakage, mechanical failure, and revision surgery, emphasizing the importance of sagittal screw trajectory for optimal outcome. Furthermore, caution should be exercised with Lenke type 5 curves. LEVELS OF EVIDENCE:Level III.

BACKGROUND:Orthopaedic management of spinal deformity in patients with early onset scoliosis (EOS) often prioritizes objective radiographic correction; radiographic improvement alone does not fully capture the treatment's meaningful benefits from the patient's perspective. The Early Onset Scoliosis Questionnaire (EOSQ-24) has been previously developed and validated to measure health-related quality of life (HRQoL) in patients with EOS. To date, the traditionally accepted assumption has been that a 10% difference in scores is clinically different. However, an evidence-based estimate for the minimal clinically important difference (MCID) in EOSQ-24 scores is needed. OBJECTIVES:To determine the MCID for the EOSQ-24 questionnaire and establish a clinically relevant threshold to assess changes in patient HRQoL. METHODS:This is a prospective, multicenter study of EOS patients. Eighty-five patients with EOS and/or their parents completed the EOSQ-24 before and after treatment, and the mean change in EOSQ-24 score was calculated. A global assessment survey using a Likert-based scale then evaluated if patients experienced a change (worsening or improvement) after the intervention, and if so, whether it was important to their HRQoL. An anchor-based MCID was determined using a receiver operating characteristic curve to find the threshold score change that optimally identified those with important change. A secondary, 1 standard error of measurement (1 SEM) distribution-based approach was then calculated using the standard deviation of pre-intervention EOSQ-24 scores and a reliability coefficient of 0.92, based on prior validation studies. These 2 methods were compared with determine the MCID. RESULTS:The mean change in EOSQ-24 score for all patients was 8.5 points (SD = 8.1). The anchor-based MCID was 5.2 with an area under the curve (AUC) of 0.600, indicating a limited discriminative ability of the EOSQ-24 score change. The data distribution-based MCID was 4.6, representing the minimum change to reflect a true difference beyond measurement error. CONCLUSIONS:The final MCID for EOSQ-24 scores in EOS patients is a 5-point change and was derived from 2 methods that were highly consistent, supporting the robustness of this threshold for meaningful change in EOSQ scores. Accurate clinician recognition of important HRQoL changes in this population is important to improve clinical care. LEVEL OF EVIDENCE:Level II.

BACKGROUND:Lumbar partial microdiscectomy (LPM) in adolescents is an infrequently performed procedure, reserved for pain and neurological symptoms unresponsive to nonsurgical management. Most studies have focused on the interventional impact on pain outcomes creating a paucity of data on physical function and mental health outcomes. The study hypothesis is LPMs in adolescents will provide improvements in measured PROMIS domains (mental health, physical function, and pain) at 2 years postoperatively. METHODS:This study is a retrospective analysis of patients under 21 years of age who underwent LPM surgery by 2 surgeons at a tertiary-care pediatric hospital. PROMIS scores [mobility (MOB), pain interference (PI), upper extremity (UE), physical functioning (PF), peer relationships (PR), anxiety, and depression] were obtained preoperatively and 6 weeks, 3 months, 6 months, 1 year, and 2+ years postoperative. The changes in PROMIS scores were then analyzed and compared at each time point using a mixed model analysis. RESULTS:Thirty-six patients with a mean age of 16.6 years (range: 13 to 20 y) at surgery were included in the analysis (2015 to 2022). All patients underwent nonsurgical treatments, which varied according to symptom type and severity and included over-the-counter medications, pain management or physiatry consultations, physiotherapy, selective nerve root and epidural injections, and bracing for a minimum of 3 months. Preoperatively, 4 patients had motor weakness, 11 lower extremity numbness, and 35 lower extremity radicular pain. Postoperatively, there were improvements for MOB ( P ≤0.05) at each time point, with an estimated mean difference of +11.3 at 2 years ( P= 0.0027). In PI there was a significant decrease ( P ≤0.0001) immediately after surgery with sustained improvement (-8.6) at 2 years ( P= 0.0009). For UE and PR, there was a statistically significant improvement from the preoperative baseline scores to the 1-year postoperative visit for UE (+10.6; P =0.008) and PR (+8.0; P =0.01), but no difference at 2 years. PF, anxiety, and depression domains did not demonstrate any statistically significant changes. CONCLUSION:Using the PROMIS instrument, there were significant improvements postoperatively after LPM in adolescents in MOB, PI, UE, and PR up to 1 year postoperatively, and continued improvement in MOB and PI. These data demonstrate LPM can provide sustained improvement in PROMIS domains up to 2 years of follow-up after surgery. LEVEL OF EVIDENCE:Level III-retrospective, single cohort study.

BACKGROUND:The Shilla Growth Guidance surgery (SGGS) aims to correct a child's spinal deformity while allowing continued spinal growth. Our study used a multicenter early-onset-scoliosis database to determine significant predictors of best candidates. METHODS:The Pediatric Spine Study Group multicenter database was analyzed for all patients who had undergone SGGS and had a minimum follow-up of 2 years. Patients without radiographic measurements preoperatively, postoperatively, and at the latest follow-up, as well as patients with myelo gibbus deformities, were excluded. These radiographs were evaluated for major curve, spinal length, and other parameters. Multivariate regressions were conducted to assess the effects of these parameters on the following 4 outcomes: (1) percent of initial curve correction, (2) scoliosis curve progression after surgery per year, (3) at least 1 unplanned SGGS-related reoperation, and (4) T1-S1 height change per year from 1st postoperative erect to final available follow-up. RESULTS:Included were 105 children; the average follow-up was 4.8±2.4 years. Scoliosis etiologies included neuromuscular (n=36; 34%), syndromic (n=31; 30%), idiopathic (n=30; 29%), and congenital (n=8; 8%). Average preoperative, 1st postoperative erect, and latest follow-up major curves measured 69, 32, and 49 degrees, respectively. Average T1-S1 postoperative height change per year was 7±9 mm and average overall T1-S1 height change was 24±35 mm. Forty-eight (46%) patients had C-shaped and 57 (54%) had S-shaped curves; 59 (56%) patients underwent ≥1 SGGS-related reoperation. Multivariate Cox-proportional hazard test revealed younger age at index surgery [hazard ratio (HR)=0.83, P =0.028] and S-shaped curves (HR=0.43, P =0.014) were associated with ≥1 reoperation. Further analysis revealed age younger than 7 years (HR=0.48, P =0.021) was correlated with an increased risk of SGGS-related reoperation. The preoperative major curve was not significantly associated with any outcome measure. A reoperation-free survival rate of 50% corresponded to 3.5 years. CONCLUSION:SGGS instrumentation in patients younger than 7 years and patients with an S-shaped curve were associated with SGGS-related unplanned surgical interventions. Despite younger age being associated with likely complications, this procedure still benefits these children and provides significant curve correction while allowing growth. LEVEL OF EVIDENCE:Level III.

Retrospective case-series The purpose of this study is to validate novel radiographic measures, specifically Rib-2 height (R2H) and T1-Rib-2 Change (T1R2C), as predictors of postoperative shoulder balance following adolescent idiopathic scoliosis (AIS) surgery. Shoulder balance following posterior spinal fusion (PSF) in AIS continues to be important for optimal aesthetic outcomes and patient satisfaction. Using currently accepted radiographic measures intraoperatively (e.g., T1-tilt) for the achievement of shoulder balance remains a challenge. Power analysis determined 28 patients were needed to achieve 80

Intraoperative neuromonitoring (IONM) reduces postoperative spinal cord dysfunction during pediatric spinal deformity surgery by allowing intraoperative corrective actions. Currently, data on false negative IONM events in this population are limited. The purpose of this study is to describe false negative IONM cases and explore immediate and final outcomes. An institutional neuromonitoring database (November 1992–April 2024) was reviewed to identify patients (0–18 years) who underwent spinal deformity surgery and experienced false negative IONM. The modalities included somatosensory evoked potentials (SSEP), descending neurogenic evoked potentials (DNEP), and transcranial motor-evoked potentials (TcMEP). Out of the 5317 consecutive cases, 16 patients (0.32

Introduction: Since the development of pedicle screw fixation in the spine, safe placement has remained a crucial component in maximizing patient outcomes and mitigating pedicle screw-related complications. The purpose of this study is to investigate the utility of pedicle tapping in identifying pedicle breaches. Methods: A pediatric spine surgery database was queried to identify a consecutive series of patients who underwent spinal deformity surgery utilizing pedicle screw fixation between May 2019 and October 2022. A “breached pedicle” was defined as a pedicle with intact walls after initial manual cannulation but found to have a breach upon probing after tapping 1 mm smaller than the planned screw diameter. The number of screws placed and breached was prospectively recorded, along with patient demographics and procedural data. Results: There were 288 patients (68% female) with a mean age of 14.3 years (range: 3.7 to 23.3). Diagnoses included idiopathic (129), neuromuscular (76), syndromic (38), congenital (23), kyphosis (9), spondylopathy (12), and trauma (1). The mean upper and lower instrumented vertebrae were T3 and L3, respectively, with an average of 1.4 posterior column osteotomies (PCOs) (range: 0 to 8). Posterior spinal fusion and segmental instrumentation (PSFSI) was the most common procedure (254 cases, 88%). Of 4796 attempted screw placements, 20 (0.4%) pedicles were breached: medial (17), lateral (1), inferior (1), and inferolateral (1). Fourteen screws were abandoned, 3 redirected, and 3 replaced by hooks. T1 (14.3%) and T6 (1.2%) had the highest breach rates. No associations were found between breached pedicles and age (P=0.099), sex (P=0.795), or PCOs (P>0.05). Congenital scoliosis had the highest breach rate at 1.6%. Conclusion: A total of 4796 pedicle screws were placed, with 1 of every 250 (0.4%) of pedicle screw insertions (n=20) having “breached pedicles” identified only after tapping. The technical step of pedicle screw tapping potentially mitigated the chance of a misplaced pedicle screw. Surgeons need to assess the value of this information in their surgical workflow and risk assessment. Level of Evidence: Level III.

The etiology of early-onset scoliosis (EOS) has been shown to significantly influence baseline parent-reported health-related quality of life (HrQOL). In combining these etiology groups, we obligatorily lump together many disparate diagnoses, particularly true in the neuromuscular (NM) cohort. We sought to evaluate the influence of underlying neuromuscular diagnosis on the HrQOL at 5 years following surgery for EOS. A retrospective review of a multi-center EOS database was performed. Children treated with primary distraction-based, growth-friendly instrumentation (GFI) for EOS with complete baseline, 2-year, and 5-year post-surgical EOSQs were included. Neuromuscular scoliosis patients, as classified by the C-EOS system, were isolated and subdivided by underlying diagnosis into 5 groups. EOSQ domains and composite HrQOL score at presentation, 2-year, and 5-year follow-up were compared across underlying diagnosis. A total of 65 neuromuscular EOS patients were identified (mean 7.6 ± 1.99 years of age, 50

STUDY DESIGN:Retrospective cohort. OBJECTIVE:Compare spinal growth guidance surgery (SpGG) and magnetically controlled growing rods (MCGR) outcomes in idiopathic early-onset scoliosis (i-EOS) using three-dimensional true spine length (3D-TSL). SUMMARY OF BACKGROUND DATA:SpGG and MCGR are techniques aimed to correct and control severe progressive spine deformity while maintaining growth. Past studies yielded comparable results between constructs using vertical coronal measures, which fail to account for growth outside plane of measurement due to three-dimensional deformity. METHODS:A multicenter database was queried for i-EOS patients undergoing MCGR or SpGG with minimum two-year follow-up. Patients were included with perioperative and two-year measurements. RESULTS:There were 161 patients (99 female; 31 SpGG/130 MCGR), with a mean age at surgery 8.1 years. 19.3% SpGG and 8.5% MCGR underwent repeat surgeries. SpGG reduced scoliosis from 67° to 26° postoperatively to 35° final (46% correction, P =0.02). MCGR reduced scoliosis 71° to 40° postoperatively to 42° final (34% correction, P <0.001). SpGG had greater coronal curve percent correction than MCGR at two years ( P =0.03). SpGG maintained maximal measured kyphosis (MMK) preoperative to immediate postoperative with increase at follow-up (41° to 43° to 50°, P =0.004). MCGR initially decreased postoperatively (49° to 36°, P <0.001) with an increase at final (+6, 42°, P =0.002). There was a significant change in MMK between SpGG and MCGR (SpGG +9 vs. MCGR-7; P <0.001). Total cohort T1 to S1 height increased (281-314 mm) and at two years (336 mm) ( P <0.001). 3D-TSL didn't significantly change preoperative to immediate postoperative (338-342 mm) for either construct. At two-year SpGG 3D-TSL increased 16.8 mm/y, whereas MCGR increased 14.2 mm/y ( P =0.2). CONCLUSIONS:At two years, 3D-TSL increased for 14.2 mm/y for MCGR and 16.8 mm/y for SpGG. Overall, SpGG and MCGR offer similar outcomes two years postoperatively as assessed by 3D-TSL. SpGG had greater coronal curve percent correction and maintained maximal kyphosis.

The etiology of early-onset scoliosis (EOS) has been shown to significantly influence baseline parent-reported health-related quality of life (HRQoL) measures as assessed by the Early Onset Scoliosis Questionnaire (EOSQ). However, it remains unclear how etiology influences mid-term outcomes following growth friendly instrumentation (GFI) for EOS. A retrospective review of a multi-center prospective spinal database was performed. Children undergoing primary distraction-based, GFI for EOS with complete baseline, 2-year, and 5-year post-surgical EOSQ were included. The identified children were subdivided by etiology as classified by the C-EOS system. EOSQ scores were compared over time according to etiology cohorts and between instrumentation types. Minimal clinically important difference (MCID) was defined as ≥ 20

INTRODUCTION:Isolated thoracic fusion (ITF) for idiopathic scoliosis preserves lumbar segment motion but risks lumbar curve progression. This study examined if Lenke classification, residual disc wedging, or tilting at the lowest instrumented vertebrae (LIV) are associated with lumbar curve progression or adding-on after ITF. METHODS:A retrospective analysis of idiopathic scoliosis patients aged 8 to 12 years treated with primary ITF was conducted. Inclusion criteria were a diagnosis of idiopathic scoliosis, LIV T10-L1, and ≥2 years of postoperative follow-up. Growth, Lenke classification, lumbar magnitude, angle of disc wedging below the LIV, and LIV tilt were assessed preoperatively, at 6 weeks postoperative, and at final follow-up. Standard descriptive statistics and repeated measures ANOVA were performed, with significance set at P <0.05. RESULTS:Fifty-seven patients were included, with a mean follow-up of 4.6 years (2 to 12 y). At surgery, 67% (38 patients) were Risser 0. There was no significant lumbar curve increase from the first (24 degrees±12) to the final follow-up (22 degrees±14, P =0.21). Patients with a lumbar curve ≥30 degrees at first follow-up (n=16) also showed no increase in curve magnitude (40 degrees±8 at first follow-up vs. 37 degrees±17 at final follow-up, P =0.47). Disc wedging ≥5 degrees and LIV tilt ≥5 degrees were not associated with lumbar curve progression (29 degrees±14 at first follow-up vs. 28 degrees±17 at final follow-up for disc wedging, P =0.52; and 30 degrees±12 at first follow-up vs. 27 degrees±16 at final follow-up for LIV tilt, P =0.28) or adding-on. Lenke classification was not associated with lumbar curve progression. However, Lenke 3 and 4 patients had larger curves immediately after surgery and final lumbar curves ≥45 degrees. Of 9 Lenke 3 and 4 patients, 3 had lumbar curves ≥45 degrees at the final follow-up. No Lenke 1 or 2 patients (0 out of 41) had lumbar curves ≥45 degrees at the final follow-up ( P <0.01). CONCLUSION:In pediatric ITF patients, disc wedging and LIV tilt were not associated with adding-on or lumbar curve progression. LEVEL OF EVIDENCE:Level III.

To determine, at 2 year follow-up, 3D spine growth for idiopathic early onset scoliosis (iEOS) patients treated with magnetically controlled growing rods (MCGR). From an international EOS registry, patients with iEOS treated with MCGR were identified. Scoliosis, kyphosis, traditional coronal height, and 3D true spine length (3D-TSL) were measured pre-index surgery, post-index, and at 2 year follow-up. 135 participants, mean age 8.1 years (2.7–15.6) were included. Scoliosis improved from 71° pre-index to 41° post-index (p < 0.001) and remained constant at 2 years (43°, p = 0.58). Kyphosis improved from 49° to 36° (p < 0.001); then increased by 2 years to 42° (p = 0.002). Traditional T1–S1 height, which reflects both spine growth and changes in deformity, increased from pre-index to post-index (274 mm vs. 310 mm; p < 0.001), and again at 2 years (332 mm, p < 0.001). As 3D-TSL reflects growth of the spine, independent of changes in deformity, as expected it did not change perioperatively (335 mm vs. 339 mm, p = 0.83), but significantly changed by 2 years (367 mm; p < 0.001). Participants < 5 years at surgery increased 22 mm (8.2

Infantile scoliosis presents a significant challenge due to high risk of pulmonary complications and morbidity. While dual growing rod constructs are often utilized, they are not always feasible in a young patient with a severe curve. In this study, we present a series of eight patients treated with a unilateral magnetically controlled growing rod (uMCGR) construct later converted to guided growth surgery (GGS). A multicenter database was queried for patients with progressive infantile scoliosis treated with uMCGR before later conversion to GGS. A minimum of 2 year follow-up was required for inclusion. Curve magnitude, trunk growth, revisions, and complications were tracked at all time points. Eight patients were included in the study. Mean age at index surgery was 4.1 years, while conversion to GGS occurred at average 7.9 years and final follow-up was at 10.5 years of age. At index procedure, major curve averaged 77.1°, which improved to 45.4°. Major curve increased to 48.4° prior to conversion, then improved to 30.9°. Major curve averaged 36.8° at final follow-up, for a maintained curve correction of 52.3

Background: Magnetic controlled growth rods (MCGR) are the most common type of implant used for operative treatment of patients with early-onset scoliosis (EOS). Rods can have either a 7-cm actuator, allowing 2.8 cm of potential expansion, or a 9-cm actuator which allows 4.8 cm potential expansion. We hypothesized that the rate of unplanned return to the operating room (UPROR) will be increased when the 9-cm actuator is implanted in smaller patients. In addition, we aimed to identify a cutoff for spine length between planned upper and lower instrumented MCGR levels that best differentiated between patients having a high versus low risk of UPROR. Methods: We identified 167 patients from a prospectively collected registry of EOS patients who began MCGR treatment at 9 years of age or younger, with greater than 1 year of follow-up, and had adequate radiographs. Demographic, clinical, and surgical characteristics were analyzed for 7-cm and 9-cm actuator patients. Chi-square tests and Student t tests were used to test for differences between the 2 actuator rod groups. A predictive model for UPROR within 2 years was developed based on variables significantly predictive of UPROR. Results: The average follow-up was 2.6 years (range, 1 to 5 y) in both the 7 cm (n=74) and 9 cm (n=93) groups. Twenty-five complications in 14 patients led to UPROR within 2 years of MCGR insertion, 8% incidence (95% CI, 4%-13%). Device-related complications (n=15) were the most common reason for UPROR, followed by wound complications (n=4), pain-related complications (n=3), junctional kyphosis (n=2), and incarcerated umbilical hernia (n=1). After adjusting for age, spine height, number of spine anchors, sex, and diagnosis, there was no significant difference in UPROR rates between groups. Fewer proximal anchors, smaller T1-S1 height, and more caudal mid-point of primary coronal curvature were significantly associated with UPROR in the predictive model. Conclusion: MCGR actuator size is not a significant factor in predicted UPROR. Smaller height, fewer anchors, and caudal apex increased UPROR risk. Level of Evidence: This is a retrospective, multicenter comparative cohort study (Level III therapeutic).

Proximal junctional kyphosis (PJK) has been reported to occur at a rate of about 30

Does differential correction of main thoracic curve (MTC) and instrumented LIV angulation based on lumbar modifiers affect radiographic outcomes, and can preoperative supine AP radiograph be used to guide correction for optimal final radiographic alignment. Retrospective analysis of idiopathic scoliosis patients who underwent selective thoracic fusions (LIV T11-L1) for Lenke 1 and 2 curve patterns, < 18 years of age. 2-year minimum follow-up. Optimal outcome meant LIV + 1 of < 5 degrees disk-wedging and C7-CSVL < 2 cm. 82 patients met inclusion criteria (70

This studies objective was to evaluate the utility of descending neurogenic-evoked potentials (DNEPs) in the setting of transcranial motor-evoked potentials (TCeMEPs) degradation into warning criteria during pediatric spinal deformity surgery. An institutional spinal cord monitoring database was queried to identify all primary and revision pediatric spinal deformity cases, < / = 21 years of age performed from 1/2006 to 12/2021, in which TCeMEPs were the primary motor tract assessment modality which degraded into warning criteria, with subsequent initiation of adjunct DNEPs. Fourteen surgical cases (0.42

Brace treatment is the most common nonoperative treatment to prevent curve progression in adolescent idiopathic scoliosis (AIS). The goal of this review and analysis is to characterize curve behavior after completion of brace treatment and to identify factors that may facilitate the estimation of long-term curve progression. A review of the English language literature was completed using the MEDLINE (PUBMED) database of publications after 1990 until September 2020. Studies were included if they detailed a minimum of 1 year post-brace removal follow-up of AIS patients. Data retrieved from the articles included Cobb angle measurements of the major curves at “in-brace,” weaning, and follow-up visit(s) for all patients described and for subset populations. From 75 articles, 18 relevant studies describing a follow-up period of 1–25 years following brace removal were included in the analyses. The reviewed literature demonstrates that curves continue to progress after brace treatment is completed with three main phases of progression: (i) immediate (upon brace removal) where a mean curve progression of 7° occurs; (ii) short term (within five years of brace removal) where a relatively high progression rate is evident (0.8°/year); and (iii) long term (more than five years after brace removal) where the progression rate slows (0.2°/year). The magnitude and rate of curve progression is mainly dependent on the degree of curve at weaning as curves weaned at < 25° progress substantially less than curves weaned at ≥ 25° at 25 years. Curves continue to progress after brace removal and the rate and magnitude of progression are associated with the curve size at weaning, with larger curves typically exhibiting more rapid and severe progression. This analysis provides physicians and patients the ability to estimate long-term curve size based on the curve size at the time of weaning. IV.

PurposeThe Law Of Diminishing Returns (LODR) has been demonstrated for traditional growing rods, but there is conflicting data regarding the lengthening behavior of Magnetically Controlled Growing Rods (MCGR). This study examines a cohort of patients with early-onset scoliosis (EOS) with rib-to-spine or rib-to-pelvis-based MCGR implants to determine if they demonstrate the LODR, and if there are differences in lengthening behaviors between the groups.MethodsA prospectively collected multicenter EOS registry was queried for patients with MCGR with a minimum 2-year follow-up. Patients with rib-based proximal anchors and either spine- or pelvis-based distal anchors were included. Patients with non-MCGR, unilateral constructs, < 3 lengthenings, or missing > 25% datapoints were excluded. Patients were further divided into Primary-MCGR (pMCGR) and Secondary-MCGR (sMCGR).Results43 rib-to-spine and 31 rib-to-pelvis MCGR patients were included. There was no difference in pre-implantation, post-implantation and pre-definitive procedure T1-T12 height, T1-S1 height, and major Cobb angles between the groups (p > 0.05). Sub-analysis was performed on 41 pMCGR and 19 sMCGR rib-to-spine patients, and 31 pMCGR and 17 sMCGR rib-to-pelvis patients. There is a decrease in rod lengthenings achieved at subsequent lengthenings for each group: rib-to-spine pMCGR (rho = 0.979, p < 0.001), rib-to-spine sMCGR (rho = 0.855, p = 0.002), rib-to-pelvis pMCGR (rho = 0.568, p = 0.027), and rib-to-pelvis sMCGR (rho = 0.817, p = 0.007). Rib-to-spine pMCGR had diminished lengthening over time for idiopathic, neuromuscular, and syndromic patients (p < 0.05), with no differences between the groups (p > 0.05). Rib-to-pelvis pMCGR neuromuscular patients had decreased lengthening over time (p = 0.01), but syndromic patients had preserved lengthening over time (p = 0.65).ConclusionRib-to-spine and rib-to-pelvis pMCGR and sMCGR demonstrate diminished ability to lengthen over subsequent lengthenings.

In idiopathic scoliosis (IS), there is general agreement ending PSFs at L3 or more cranial is preferred to optimize spinal motion, and extending PSFs to L4 may be necessary; however, this may also cause coronal imbalance or caudal disc wedging post-operatively due to leveling of L4 tilt. The purpose of this study was to identify a pre-operative radiographic measurement, which can be used to quantify the optimal amount of L4 tilt for ideal post-operative radiographic alignment. The study was a retrospective analysis of IS patients who underwent PSF to L4, with minimum 2-year follow-up post-operatively. Optimal outcome was defined by coronal balance, and L4–5 and L5–S1 disc wedging. 44 patients (84