Evidence of spinal stiffening following fusionless bipolar fixation for neuromuscular scoliosis: a shear wave elastography assessment of lumbar annulus fibrosus.

OBJECTIVES: There are no established criteria for stiffness after fusionless surgery for neuromuscular scoliosis (NMS). As a result, there is no consensus regarding the surgical strategy to propose at long-term follow-up. This study reports the first use of shear wave elastography for assessing the mechanical response of lumbar intervertebral discs (IVDs) after fusionless bipolar fixation (FBF) for NMS and compares them with healthy controls. The aim was to acquire evidence from the stiffness of the spine following FBF. PATIENTS AND METHODS: Nineteen NMS operated on with FBF (18 ± 2y at last follow-up, 6 ± 1 y after surgery) were included prospectively. Preoperative Cobb was 89 ± 20° and 35 ± 1° at latest follow-up. All patients had reached skeletal maturity. Eighteen healthy patients (20 ± 4 y) were also included. Shear wave speed (SWS) was measured in the annulus fibrosus of L3L4, L4L5 and L5S1 IVDs and compared between the two groups. A measurement reliability was performed. RESULTS: In healthy subjects, average SWS (all disc levels pooled) was 7.5 ± 2.6 m/s. In NMS patients, SWS was significantly higher at 9.9 ± 1.4 m/s (p < 0.05). Differences were significant between L3L4 (9.3 ± 1.8 m/s vs. 7.0 ± 2.5 m/s, p = 0.004) and L4L5 (10.3 ± 2.3 m/s vs. 7.1 ± 1.1 m/s, p = 0.0006). No difference was observed for L5S1 (p = 0.2). No correlation was found with age at surgery, Cobb angle correction and age at the SWE measurement. CONCLUSIONS: This study shows a significant increase in disc stiffness at the end of growth for NMS patients treated by FBF. These findings are a useful adjunct to CT-scan in assessing stiffness of the spine allowing the avoidance of surgical final fusion at skeletal maturity.

Flexible posterior vertebral tethering for the management of Scheuermann's kyphosis: correction by using growth modulation-clinical and radiographic outcomes of the first 10 patients with at least 3 years of follow-up.

PURPOSE: The present prospective cohort study was intended to present the minimum 3 years' results of flexible posterior vertebral tethering (PVT) applied to 10 skeletally immature patients with SK to question, if it could be an alternative to fusion. METHODS: Ten skeletally immature patients with radiographically confirmed SK, who had flexible (minimum 35%) kyphotic curves (T2-T12), were included. A decision to proceed with PVT was based on curve progression within the brace, and/or persistent pain, and/or unacceptable cosmetic concerns of the patient/caregivers, and/or non-compliance within the brace. RESULTS: Patients had an average age of 13.1 (range 11-15) and an average follow-up duration of 47.6 months (range 36-60). Posterior vertebral tethering (PVT) was undertaken to all patients by utilizing Wiltse approach and placing monoaxial pedicle screws intermittently. At the final follow-up: mean pre-operative thoracic kyphosis and lumbar lordosis improved from 73.6°-45.7° to 34.7°-32.1°. Mean sagittal vertical axis, vertebral wedge angle and total SRS-22 scores improved significantly. A fulcrum lateral X-ray obtained at the latest follow-up, showed that the tethered levels remained mobile. CONCLUSION: This study, for the first time in the literature, concluded, that as a result of growth modulation applied to skeletally immature patients with SK, flexible PVT was detected to yield gradual correction of the thoracic kyphosis by reverting the pathological vertebral wedging process, while keeping the mobility of the tethered segments in addition to successful clinical-functional results. The successful results of the present study answered the role of the PVT as a viable alternative to fusion in skeletally immature patients with SK. LEVEL OF EVIDENCE: IV.

Spontaneous induced bone fusion in minimally invasive fusionless bipolar fixation in neuromuscular scoliosis: a computed tomography analysis.

PURPOSE: Posterior spinal fusion (PSF) at skeletal maturity is still the gold standard in children with neuromuscular scoliosis (NMS) who underwent fusionless surgery. The aim of this computed tomography (CT) study was to quantify the spontaneous bone fusion at the end of a lengthening program by minimally invasive fusionless bipolar fixation (MIFBF), that could avoid PSF. METHODS: NMS operated on with MIFBF from T1 to the pelvis and at final lengthening program were included. CT was performed at least five years postoperatively. The autofusion was classified as completely or not fused at the facets joint (on both coronal and sagittal plane, right and left side, from T1 to L5), and around the rods (axial plane, right and left side, from T5 to L5). Vertebral body heights were assessed. RESULTS: Ten patients were included (10.7y ± 2 at initial surgery). Mean Cobb angle was 82 ± 20 preoperatively and 37 ± 13 at last follow-up. CT were performed on average 6.7y ± 1.7 after initial surgery. Mean preoperative and last follow-up thoracic vertebrae height were respectively 13.5 mm ± 1.7 and 17.4 mm ± 1.7 (p < 0.001). 93% facets joints were fused (out of 320 analyzed joints), corresponding to 15/16 vertebral levels. Ossification around the rods was observed in 6.5±2.4 levels out of 13 in the convex side, and 4.2 ± 2.2 in the concave side (p = 0.04). CONCLUSIONS: This first computed quantitative study showed MIFBF in NMS preserved spinal growth, while it induced 93% of facet joints fusion. This could be is an additional argument when questionning the real need for PSF at skeletal maturity.

An investigation of range of motion preservation in fusionless anterior double screw and cord constructs for scoliosis correction.

PURPOSE: To evaluate the motion-preserving properties of vertebral body tethering with varying cord/screw constructs and cord thicknesses in cadaveric thoracolumbar spines. METHODS: In vitro flexibility tests were performed on six fresh-frozen human cadaveric spines (T1-L5) (2 M, 4F) with a median age of 63 (59-to-80). An ± 8 Nm load was applied to determine range of motion (ROM) in flexion-extension (FE), lateral bending (LB), and axial rotation (AR) in the thoracic and lumbar spine. Specimens were tested with screws (T5-L4) and without cords. Single (4.0 mm and 5.0 mm) and double (4.0 mm) cord constructs were sequentially tensioned to 100 N and tested: (1) Single 4.0 mm and (2) 5.0 mm cords (T5-T12); (3) Double 4.0 mm cords (T5-12); (4) Single 4.0 mm and (5) 5.0 mm cord (T12-L4); (6) Double 4.0 mm cords (T12-L4). RESULTS: In the thoracic spine (T5-T12), 4.0-5.0 mm single-cord constructs showed slight reductions in FE and 27-33% reductions in LB compared to intact, while double-cord constructs showed reductions of 24% and 40%, respectively. In the lumbar spine (T12-L4), double-cord constructs had greater reductions in FE (24%), LB (74%), and AR (25%) compared to intact, while single-cord constructs exhibited reductions of 2-4%, 68-69%, and 19-20%, respectively. CONCLUSIONS: The present biomechanical study found similar motion for 4.0-5.0 mm single-cord constructs and the least motion for double-cord constructs in the thoracic and lumbar spine suggesting that larger diameter 5.0 mm cords may be a more promising motion-preserving option, due to their increased durability compared to smaller cords. Future clinical studies are necessary to determine the impact of these findings on patient outcomes.

Long-term outcomes of ilio-sacral screws in minimally invasive bipolar fusionless technique for neuromuscular scoliosis: a retrospective study in 167 patients.

INTRODUCTION: Pelvic fixation in patients with neuromuscular scoliosis is difficult, due to their fragile general condition and poor bone quality. Many techniques have been described, associated with high rates of mechanical complications. The objective of this work was to evaluate the mechanical complications and long-term radiological results of ilio-sacral screw pelvic fixation. MATERIALS AND METHODS: 167 consecutive patients with neuromuscular scoliosis who underwent minimally invasive bipolar fixation with ilio-sacral screw pelvic fixation were retrospectively reviewed. The instrumentation consisted in a bilateral sliding rods construct extended from T1 to the sacrum, anchored proximally by double-hook claws and distally by ilio-sacral screws through a minimally invasive approach. Mechanical complications and radiographic measurements (angle of the major coronal curve, pelvic obliquity, lumbar lordosis) were evaluated preoperatively, postoperatively, and at the last follow-up. RESULTS: Mean operative age was 12 ± 3 years, and follow-up 6.4 years (3.0-10.4 years). Pelvic obliquity decreased from 20° preoperatively to 5° (77% correction) at last follow-up, Angle of the major coronal curve from 75° to 36° (52% correction), and lumbar lordosis from 28° to 38°. 16 mechanical complications in nine patients occurred: screw prominence (n = 1), connector failure (n = 4), screw malposition (n = 11). Unplanned surgery was required in seven cases, two were managed during rod lengthening, seven did not require treatment. CONCLUSION: In this series of neuromuscular patients operated by ilio-sacral screws as pelvic fixation, the results were stable with a mean follow-up of more than 6 years and the complication rate was reduced comparatively to the literature.

Perioperative complications after posterior spinal fusion versus minimally invasive fusionless surgery in neuromuscular scoliosis: a comparative study.

INTRODUCTION: Early-onset scoliosis is a common deformity in neuromuscular disease. When conservative treatment becomes ineffective, several surgical options can be proposed. The most common technique is posterior spinal fusion (PSF) consisting of performing a multiple segmental instrumentation with pedicular screws on the full spine associated with decortication and bone graft. Minimally invasive fusionless surgery (MIFS) is an alternative to correct and fix definitively the spine without graft. The objective of this study was to compare early surgical inpatient period between PSF and MIFS in neuromuscular scoliosis. MATERIAL AND METHODS: 140 NMS operated by PSF or MIFS between 2012 and 2017 was retrospectively reviewed. The following data were compared between groups: general characteristics (age, sex, etiology), preoperative preparation (halo traction, noninvasive ventilation or tracheostomy), Cobb angle and pelvic obliquity correction, use of drugs (vasopressor and/or inotropes, expansion fluids, transfusion and volumes), postoperative complications, and need of noninvasive ventilation. RESULTS: 75 patients were managed by PSF with a mean age of 14.3 ± 2.3y and 65 by MIFS with a mean age of 11.8 ± 3y. Average pelvic obliquity and major curve correction were similar postoperatively. Intraoperative blood transfusion was significantly more common in PSF group (OR, 14; 95% CI [6.3-33.0]). Vasopressors were used non-significantly more often in the PSF group and expansion fluids similar in the two groups. PSF group had more overall complications (OR, 4.6; 95% CI [2.3-9.8]), more infections (OR, 3.6; 95% CI [1.5-9.3]) and more hemodynamic complications (OR, 4.1; 95% CI [1.4-15.1]). Average intubation duration was 5 days in the PSF and 4 days in MIFS (p = 0.05). CONCLUSION: In this series of neuromuscular patients, the complication rate was reduced in MIFS comparatively to PSF, with lower blood transfusion and less infections.

Analysis of the pulmonary function in patients undergoing vertebral body tethering for adolescent idiopathic scoliosis.

PURPOSE: The literature concerning the effects of scoliosis correction on pulmonary function (PF) is scarce and solely related to spinal fusion. Vertebral body tethering (VBT) represents a new option for scoliosis correction; however, its effects on PF have not yet been investigated. As VBT is a fusion-less technique that does not limit the dynamics of the chest wall, it is expected not to have a negative impact on PF despite the anterior surgical approach. METHODS: We analyzed the PF preoperatively and compared it with the PF at 6-weeks, 6-months and 12-monthts postoperatively. Considered parameters were total lung capacity (TLC), forced expiratory volume in 1 s (FEV1) and forced vital capacity (FVC) expressed as percentages. A change of more than 10% was considered clinically significant. RESULTS: Before VBT, overall TLC, FEV1 and FVC measured 98 ± 15%, 85 ± 16% and 91 ± 17%, respectively. Six weeks after surgery, all parameters were comparable to the preoperative values (TLC 96 ± 17%, FEV1 84 ± 14%, FVC 90 ± 16%) and remained so at the last follow-up (TLC 99 ± 15%, FEV1 89 ± 9%, FVC 86 ± 9). While a reduction in FEV1 and FVC was observed at 6-weeks and 6-months in patients with thoracic or double curves compared to thoracolumbar curves, no significant differences were observed at the 12-months follow-up. CONCLUSIONS: VBT does not cause a reduction in PF values at a short-term follow-up.

Motion preservation surgery for scoliosis with a vertebral body tethering system: a biomechanical study.

PURPOSE: There is a paucity of studies on new vertebral body tethering (VBT) surgical constructs especially regarding their potentially motion-preserving ability. This study analyses their effects on the ROM of the spine. METHODS: Human spines (T10-L3) were tested under pure moment in four different conditions: (1) native, (2) instrumented with one tether continuously connected in all vertebrae from T10 to L3, (3) additional instrumented with a second tether continuously connected in all vertebrae from T11 to L3, and (4) instrumented with one tether and one titanium rod (hybrid) attached to T12, L1 and L2. The instrumentation was inserted in the left lateral side. The intersegmental ROM was evaluated using a magnetic tracking system, and the medians were analysed. Please check and confirm the author names and initials are correct. Also, kindly confirm the details in the metadata are correct. The mentioned information is correct RESULTS: Compared to the native spine, the instrumented spine presented a reduction of less than 13% in global ROM considering flexion-extension and axial rotation. For left lateral bending, the median global ROM of the native spine (100%) significantly reduced to 74.6%, 66.4%, and 68.1% after testing one tether, two tethers and the hybrid construction, respectively. In these cases, the L1-L2 ROM was reduced to 68.3%, 58.5%, and 38.3%, respectively. In right lateral bending, the normalized global ROM of the spine with one tether, two tethers and the hybrid construction was 58.9%, 54.0%, and 56.6%, respectively. Considering the same order, the normalized L1-L2 ROM was 64.3%, 49.9%, and 35.3%, respectively. CONCLUSION: The investigated VBT techniques preserved global ROM of the spine in flexion-extension and axial rotation while reduced the ROM in lateral bending.

Analysis of the risk factors for early tether breakage following vertebral body tethering in adolescent idiopathic scoliosis.

INTRODUCTION: Tether breakage is a common mechanical complication after VBT. When this occurs shortly after surgery, patients may be at higher risk for loss of correction. Aim of this study was to analyze demographic and radiographic parameters that may potentially be risk factors for early tether breakage, as no data are yet available on this topic. MATERIALS AND METHODS: All skeletally immature patients who underwent VBT and for whom a 1-year follow-up was available were included in the study. Demographic, intraoperative and coronal and sagittal parameters from the preoperative and 1st standing X-rays were collected. Patients were divided in two groups according to the presence or absence of a breakage and the outcomes of interest were compared. RESULTS: Data from 105 patients were available (age 14.2 ± 1.5, 153 curves). Lumbar curves showed a higher risk of breakage than thoracic ones (71% vs. 29%, P < 0.0001). Overall, preoperative risk factors were a high curve magnitude (MD, mean difference - 4.1°, P = 0.03) and a limited flexibility (MD 8.9%, P = 0.006); postoperative risk factors were a large residual curve (MD - 6.4°, P = 0.0005) and a limited correction (MD 8.4%, P = 0.0005). The same risk factors were identified in thoracic curves, while in lumbar instrumentation only a higher preoperative Cobb angle represented a risk factor for breakage. Age and skeletal maturity did not represent risk factors. CONCLUSION: The main preoperative risk factors for early tether breakage after VBT are a high curve magnitude and a limited flexibility. A limited curve correction also represents a risk factor for this complication.

The timing of tether breakage influences clinical results after VBT.

INTRODUCTION: Tether breakage is a frequent mechanical complications after vertebral body tethering (VBT), but not all patients with a breakage show loss of correction. The reason of this clinical finding has not yet been clarified. We hypothesized that the integrity of the tether is relevant only in the early stages after VBT, when it drives growth modulation and tissue remodelling. After these mechanisms have taken place, the tether loses its function and a breakage will not alter the new shape of the spine. Thus, tether breakage would have a greater clinical relevance when occurring shortly after surgery. METHODS: All consecutive patients who underwent VBT and had a min. 2-year follow-up were included. The difference in curve magnitude between the 1st standing x-ray and the last follow-up was calculated (ΔCobb). For each curve, the presence and timing of tether breakage were recorded. The curves were grouped according to if and when the breakage was observed (no breakage, breakage at 0-6 months, 6-12 months, > 12 months). The ΔCobb was compared among these groups with the analysis of variance (ANOVA). RESULTS: Data from 152 curves were available: 68 with no breakage, 12 with a breakage at 0-6 months, 37 at 6-12 months and 35 > 12 months. The ANOVA found significant difference in the ΔCobb among the groups (Sum of square 2553.59; degree of freedom 3; mean of square 851.1; Fisher test 13.8; P < 0.0001). Patients with no breakage or breakage at > 12 months had similar ΔCobb (mean 4.8° and 7.8°, respectively, P = 0.3), smaller than the 0-6 or 6-12 groups (15.8° and 13.8°, respectively). CONCLUSION: Tether breakage leads to a consistent loss of correction when occurring within the first 12 months, while it has limited clinical relevance when occurring later on.

The effects of vertebral body tethering on sagittal parameters: evaluations from a 2-years follow-up.

INTRODUCTION: While the effects of VBT on coronal parameters have been investigated in various studies, this has not yet been the case for sagittal parameters. This is of particular relevance considering that VBT does not allow direct correction of the sagittal profile. Thus, we investigated the effects of VBT on sagittal parameters in patients with adolescent idiopathic scoliosis. MATERIALS AND METHODS: Retrospective, 2-Center study. Patients who underwent VBT and presented a 2-years follow-up were included. The differences in sagittal parameters were evaluated, along with modifications of sagittal profile following Abelin-Genevois' classification. RESULTS: Data from 86 patients were obtained. Mean Cobb angle was 52.4 ± 13.9° at thoracic level and 47.6 ± 14.3° at lumbar level before surgery, and 28.5 ± 13.6 and 26.6 ± 12.7° at the 2-year follow-up, respectively. Mean thoracic kyphosis increased from 28.3 ± 13.8 to 33 ± 13°, the lumbar lordosis (LL) was unvaried (from 47.5 ± 13.1 to 48.4 ± 13.5°), PT decreased from 9.4 ± 8.5 to 7.4 ± 6.1°, the sagittal vertical axis SVA decreased from 4.5 ± 31.4 to - 3.6 ± 27.9 mm. No kyphotic effect on LL in patients who underwent lumbar instrumentation was observed. Before surgery, 39 patients had a type 1 sagittal profile, 18 were type 2a, 14 type 2b and 15 type 3. Postoperatively, 54 were type 1, 8 were 2a, 13 were 2b and 11 were type 3. CONCLUSIONS: VBT positively influences sagittal parameters and does not have a kyphotic effect on LL.

Preliminary outcomes after vertebral body tethering (VBT) for lumbar curves and subanalysis of a 1- versus 2-tether construct.

INTRODUCTION: Aim of this study was to analyze the rate of tether breakages after lumbar vertebral body tethering (VBT) and to study the effects and possible benefits of the use of a 2-tether construct. Tether breakage is a known mechanical complication after VBT. However, the literature only refers to thoracic VBT, and no data on the breakage rate or 2-tether construct after lumbar VBT are available. MATERIALS AND METHODS: Patients who underwent lumbar VBT with lowest instrumented vertebra at L3 or L4 and had a 1-year follow-up were included. Radiologic data were obtained preoperatively, at the 1st standing X-ray and at the 1-year follow-up to study breakage rate, loss of correction and lumbar lordosis in 1- and 2-tether constructs. RESULTS: Data from 30 patients (mean age 14.7 ± 1.8) were available, 12 with double tether. Double tether did not decrease lumbar lordosis. The breakage rate was 24% in segments instrumented with a single tether and 16% in segments instrumented with a double tether (OR 1.6, p = 0.4). Lumbar loss of correction was 10° ± 6.8° in the entire cohort and 12.1° ± 5.4° in patients with a breakage (p = 0.2). Revision rate was 10%, due to tether breakage and loss of correction. CONCLUSION: Breakage rate after lumbar VBT is high, but was improved with the use of a 2-tether construct. Despite tether breakage, loss of correction was limited and the revision rate low. The use of a double tether does not have a kyphotic effect on the lumbar spine.

Return to sport and daily life activities after vertebral body tethering for AIS: analysis of the sport activity questionnaire.

PURPOSE: Vertebral body tethering (VBT) is an alternative to fusion for selected scoliosis patients. As VBT does not limit spine mobility, it has been propagated that this technique allows a quicker return to physical activity than fusion. However, no data are available to support this statement. Aim of this study was to quantify how much time patients required to resume preoperative activity level and to seek possible associations between return to physical activity and demographic, radiographic and surgical data. METHODS: One year postoperatively, the validated sport activity questionnaire (SAQ) was administered to all skeletally immature patients who underwent VBT at our institution. SAQ data were analyzed and a multivariate analysis was conducted to investigate associations between SAQ and demographic, radiographic and surgical data. RESULTS: Thirty-one patients aged 14.5 years completed the SAQ. Within 3 months from VBT, 97% returned to school, 61% resumed physical education, 97% carried a backpack, 68% run, and 82% rode a bike; 70% bent within a month from VBT. Ninety-four percent of patients returned to their preoperative athletic level. Within 3 months, 63% of responders resumed noncontact, 61% contact and 53% collision sports. No relevant associations were observed between the SAQ and demographic, radiographic and surgical data. In particular, number of instrumented vertebrae, level of the lowest instrumented vertebra and postoperative Cobb angle did not influence patients' return to preoperative activities. CONCLUSION: VBT allows patients to quickly return to their preoperative activity level, irrespectively of the postoperative Cobb angle or type of instrumentation.

Staged insertion of growing rods in severe scoliosis.

PURPOSE: The objective of this retrospective chart and radiographic review was to present the clinical outcomes and complication rate of a staged approach to modern dual growing-rod (GR) surgery when treating children with severe early onset scoliosis. METHODS: Fifteen patients received a 6-mm dual GR system. During Stage 1, pairs of end vertebra were exposed in a subperiosteal fashion, instrumented, grafted, and fused. Stage 2 was performed, on average, 5 months later (range 8-35 weeks) and the fused foundations were connected with two growing rods under skull-femoral traction. Clinical and operative notes were reviewed and all complications were recorded. Radiographic measurements were assessed at pre-index, with intraoperative traction during Stage 1, post-Stage 2 and at most recent follow-up. Statistical analyses were performed to evaluate change in scoliosis and kyphosis. RESULTS: At initial surgery, the average age was 8.17 ± 1.5 years. The mean Cobb angle was 88.1° ± 14.0°, corrected to 60.3° ± 8.7° (p < 0.001) with intraoperative traction in Stage 1, preserved after Stage 2 instrumentation (59.5° ± 9.6°, p = 0.69), and maintained with subsequent lengthenings (60.6° ± 12.8°, p = 0.73). Hyperkyphosis (11/15 patients) improved from 70.8° ± 15.7° to 46.6° ± 9.7° (p < 0.001). At minimum 2-year follow-up (range 24-80 months, mean 49.5), the complication rate was 14 (0.93 complications/patient), including 6 rod breakages, 6 superficial infections, and 2 deep infections. No anchor migration or pull-out was noted. Seven patients have undergone definitive posterior spinal fusion. CONCLUSIONS: Staged insertion of dual GR systems permits strong distraction, with acceptable correction of severe deformities and minimal complications. These slides can be retrieved under Electronic Supplementary Material.

Minimally invasive, robot-assisted iliosacral screw insertion for fusionless fixation in children with neuromuscular scoliosis.

Fusionless surgery coupled with growing rod techniques is increasingly advocated for the treatment of early-onset scoliosis in general and neuromuscular scoliosis in particular. Iliosacral screws have excellent biomechanical characteristics but are hard to place safely. Here, the authors report on robot-assisted iliosacral screw positioning as part of growing rod surgery for the fusionless correction of early-onset scoliosis. The technique is based on a bilateral double sliding rod construct anchored to the pelvis proximally with 6 hooks or sublaminar bands and distally with iliosacral screws placed by the robot. The video can be found here: https://youtu.be/5HGH_DiD-ck .

Porcine spine finite element model: a complementary tool to experimental scoliosis fusionless instrumentation.

PURPOSE: Developing fusionless devices to treat pediatric scoliosis necessitates lengthy and expensive animal trials. The objective was to develop and validate a porcine spine numerical model as an alternative platform to assess fusionless devices. METHODS: A parametric finite element model (FEM) of an osseoligamentous porcine spine and rib cage, including the epiphyseal growth plates, was developed. A follower-type load replicated physiological and gravitational loads. Vertebral growth and its modulation were programmed based on the Hueter-Volkmann principle, stipulating growth reduction/promotion due to increased compressive/tensile stresses. Scoliosis induction via a posterior tether and 5-level rib tethering, was simulated over 10 weeks along with its subsequent correction via a contralateral anterior custom tether (20 weeks). Scoliosis induction was also simulated using two experimentally tested compression-based fusionless implants (hemi- and rigid staples) over 12- and 8-weeks growth, respectively. Resulting simulated Cobb and sagittal angles, apical vertebral wedging, and left/right height alterations were compared to reported studies. RESULTS: Simulated induced Cobb and vertebral wedging were 48.4° and 7.6° and corrected to 21° and 5.4°, respectively, with the contralateral anterior tether. Apical rotation (15.6°) was corrected to 7.4°. With the hemi- and rigid staples, Cobb angle was 11.2° and 11.8°, respectively, with 3.7° and 2.0° vertebral wedging. Sagittal plane was within the published range. Convex/concave-side vertebral height difference was 3.1 mm with the induction posterior tether and reduced to 2.3 with the contralateral anterior tether, with 1.4 and 0.8 for the hemi- and rigid staples. CONCLUSIONS: The FEM represented growth-restraining effects and growth modulation with Cobb and vertebral wedging within 0.6° and 1.9° of experimental animal results, while it was within 5° for the two simulated staples. Ultimately, the model would serve as a time- and cost-effective tool to assess the biomechanics and long-term effect of compression-based fusionless devices prior to animal trials, assisting the transfer towards treating scoliosis in the growing spine.

Early onset scoliosis with intraspinal anomalies: management with growing rod.

OBJECTIVE: To evaluate clinical and radiological outcomes of growing rod (GR) in the management of Early Onset Scoliosis (EOS) with intraspinal anomalies. BACKGROUND DATA: The effect of repeated distractions following GR, in the presence of intraspinal anomalies has not been studied. METHODS: During 2007-2012, 46 patients underwent fusionless surgery. Out of these 46 patients, 13 patients had one or more intraspinal anomalies. 11 patients had undergone prior neurosurgical procedure while 2 (filum terminale lipoma and syringomyelia) did not. A total of 88 procedures were conducted during the treatment period; 13 index surgeries, 74 distractions of GR and 1 unplanned surgery. RESULTS: The age at surgery was 6.8 ± 2.5 years (3.5-12 years). 11 patients had congenital scoliosis and 2 had idiopathic scoliosis. A total of 19 (41.30 %) intraspinal anomalies [Tethered Cord Syndrome (TCS) 08, Split Cord Malformation (SCM) 08, Syringomyelia 01, Meningomyelocele 01, Filum terminale Lipoma 01] were seen. The average lengthening procedures per patient were 5.7 (4-9) with distraction interval of 6.7 (6-7.25) months. Pre-operative Cobb angle was 78.50 ± 18.1 (54-114°) and improved to 53.10 ± 16.70 (36-84°) at final follow-up. A total of 15 complications related to implant (9), wound (2), anesthesia (2) and neurological (2) occurred in 7 patients. Among the two neurological complications, one patient sustained fall in the post-op period and reported to the emergency department with paraplegia and broken proximal screw. While other patient experienced MEP changes during index procedure. None of the patients had any neurological complications during repeated lengthening procedures. CONCLUSION: The most common cord anomalies associated with EOS in our study are TCS and SCM. Although presence of previous intraspinal anomaly does not seem to increase the incidence of neurological deficit, use of neuromonitoring is advisable for all index procedure and selected distractions. STUDY DESIGN: Level 4 (case series).

Anterior vertebral tethering for adolescent idiopathic scoliosis: our initial ten year clinical experience.

BACKGROUND: Anterior vertebral tethering (AVT) is a minimally invasive alternative to fusion surgery for adolescent idiopathic scoliosis (AIS) that offers the potential for definitive scoliosis treatment with the possibility of preservation of the growth, motion, function and overall health of the spine. This study represents our first ten years using AVT to treat AIS. METHODS: In this retrospective review we analyzed our first 74 AIS patients treated with AVT 2010-2020. Multiple Lenke curve types 33-70° were treated with skeletal maturity spanning Risser -1 to 5. RESULTS: Of 74 consecutive AIS patients treated with AVT, 52 patients (47 female, 5 male) had sufficient 2-year follow-up for inclusion. Forty-six of these 52 patients (88%) with 65 curves (35T, 30TL/L) were satisfactorily treated with AVT demonstrating curve correction from 48.6° pre-op (range 33°-70°) at age 15.1 years (range 9.2-18.8) and skeletal maturity of Risser 2.8 (range -1 to 5) to 23.2° post-op (range 0°-54°) and 24.0° final (range 0°-49°) at 3.3 years follow-up (range 2-10 years). Curve corrections from pre-op to post-op and pre-op to final were both significant (p < 0.001). The 0.8° change from post-op to final was not significant but did represent good control of scoliosis correction over time. Thoracic kyphosis and lumbar lordosis were maintained in a normal range throughout while axial rotation demonstrated a slight trend toward improvement. Skeletal maturity of Risser 4 or greater was achieved in all but one patient. Four of the 52 patients (8%) required additional procedures for tether rupture (3 replacements) or overcorrection (1 removal) to achieve satisfactory treatment status after AVT. An additional 6 of the 52 patients (12%), however, were not satisfactorily treated with AVT, requiring fusion for overcorrection (2) or inadequate correction (4). CONCLUSIONS: In this study, AIS was satisfactorily treated with AVT in the majority of patients over a broad range of curve magnitudes, curve types, and skeletal maturity. Though late revision surgery for overcorrection, inadequate correction, or tether rupture was not uncommon, the complication of overcorrection was eliminated after our first ten patients by a refinement of indications. LEVEL OF EVIDENCE: IV.

Frequency and management of rod fractures following minimally invasive bipolar fusionless surgery in neuromuscular scoliosis patients.

INTRODUCTION: Neuromuscular scoliosis (NMS) is associated with an abnormal muscle tone. Traditional conservative treatments, with the historical practice of early posterior fusion, have proven ineffective. Recently, growth-sparing techniques have gained traction owing to their ability to maximize trunk height. However, these techniques have a substantial risk of complications, particularly rod breakage, with reported incidence rates ranging from 15 % to 42 %. The objective of this study was to conduct a descriptive analysis of NMS patients who experienced rod breakage following the minimally invasive fusionless surgery (MIFS) technique. METHODS: This was a single-center, retrospective study that included all NMS patients who underwent surgery between January 2015 and January 2021 and subsequently presented with rod breakage after MIFS. The MIFS technique is based on proximal fixation with double hook claws made of pedicular and -sus laminar hooks and pelvic fixation with iliosacral screws. RESULTS: The mean follow-up was 5.2 ± 2.2 years. The mean dominant etiology of NMS was cerebral palsy (67 %). Of the 217 patients who underwent surgery, 15 (6.9 %) developed rod breakage. Rod breakage occurred 2.7 ± 1.3 years after the initial surgery. Four cases of rod fracture recurrence were reported in ambulatory patients with dystonia or hyperactivity. CONCLUSION: Compared with other fusionless techniques, the minimally invasive bipolar technique appears promising for patients with NMS, with a lower rate of rod breakage. We recommend the use of a four-rod construct for ambulatory patients or for those with dystonia or hyperactivity.

Placement of ilio-sacral screws in fusionless technique for pediatric neuromuscular scoliosis utilizing planning software, in conjunction with intraoperative navigation, results in a safer optimal screw: a CT-based study.

PURPOSE: The insertion of ilio-sacral (IS) screws for distal anchoring in the instrumentation of pediatric neuromuscular scoliosis (NS) presents a significant challenge, often leading to elevated rates of complications. Utilizing computed tomography (CT) navigation and preoperative planning technology is proposed as a potential solution to mitigate these challenges. This study aims to assess the precision of IS screw placement through CT-graphic measurements, both with and without preoperative planning, followed by navigated IS screw insertion, in pediatric neuromuscular scoliosis. METHODS: Thirty-two treated patients were grouped based on surgical procedure: planned (P): 19 patients (n = 38 screws) and non-planned (NP): 13 patients (n = 26 screws). All screw placements (P and NP) took place under CT navigation. IS screw trajectories of P-group were drawn preoperatively on CT images with the cranial trajectory planning program and fused with the intraoperative CT images. There are several important anatomical structures that should be avoided when placing the IS screw (L5 root, spinal canal, L5S1 facet, SI joint, neurovascular structures anteriorly to the sacrum, S1 root in the S1 foramen and the intestines). Each trajectory was evaluated based on seven radiographical parameters whom we have enlisted partially based on the essentials of a good trajectory described by Miladi et al. (1: Ilium; 2: SI joint; 3: Promontorium; 4: Sacral plate; 5: Anterior sacral cortex; 6: S1 foramen; 7: Spinal canal). An independent sample T test was executed to compare both groups. RESULTS: The trajectories in the P group showed a significantly (P < 0.05) higher overall similarity and optimality (12.1 ± 2.1 vs 9.1 ± 2.2 points) compared to the non-planned trajectory. CONCLUSIONS: Preoperative planning and navigated placement of IS screws on fusion images with intraoperative CT, results in a better trajectory of the ilio-sacral screws.