Utility of intraoperative neurophysiological monitoring in detecting motor and sensory nerve injuries in pediatric high-grade spondylolisthesis.

BACKGROUND CONTEXT: Intraoperative neuromonitoring (IONM) during surgical correction of spinal deformity has been shown to reduce iatrogenic injury in pediatric and adult populations. Although motor-evoked potentials (MEP), somatosensory-evoked potentials (SSEP), and electromyography (EMG) have been shown to be highly sensitive and specific in detecting spinal cord and nerve root injuries, their utility in detecting motor and sensory nerve root injury in pediatric high-grade spondylolisthesis (HGS) remains unknown. PURPOSE: We aim to assess the diagnostic accuracy and therapeutic impact of unimodal and multimodal IONM in the surgical management of HGS. STUDY DESIGN/SETTING: Retrospective cohort study. PATIENT SAMPLE: Pediatric patients undergoing posterior spinal fusion (PSF) for treatment of HGS. OUTCOME MEASURES: Data on patient demographics, spinopelvic and spondylolisthesis parameters, and the presence of pre-and postoperative neurological deficits were collected. METHODS: Intraoperative MEP, SSEP, and EMG alerts were recorded. Alert criteria were defined as a change in amplitude of more than 50% for MEP and/or SSEP, with or without change in latency, and more than 10 seconds of sustained EMG activity. Sensitivity, specificity, positive predictive value (PPV), negative predictive value (NPV), and accuracy were calculated for each modality and the combination of MEP and SSEP. The 95% confidence intervals (CIs) were calculated using the exact (Clopper-Pearson) method. RESULTS: Fifty-four pediatric patients with HGS undergoing PSF between 2003 and 2021 in a single tertiary center were included. Seventy-two percent (39/54) of patients were female; the average age of patients was 13.7±2.3 years. The sensitivity of MEP in detecting new postoperative neurologic deficit was 92.3% (95% CI [64.0-99.8]), SSEP 77.8% (95% CI [40.0-97.2]), EMG 69.2% (95% CI [38.6-90.9]), and combination MEP and SSEP 100% (95% CI [73.5-100]). The specificity of MEP was 80.0% (95% CI [64.4-91.0]), SSEP 95.1% (95% CI [83.5-99.4]), EMG 65.9% (95% CI [49.4-79.9]), and combination MEP and SSEP 82.9% (95% CI [67.9-92.9]). The accuracy of SSEP was 92.0% (95% CI [80.8%-97.8%]), and the combination of MEP and SSEP was 86.8% (95% CI [74.7%-94.5%]). Twelve (22.2%) patients had a new motor or sensory deficit diagnosed immediately postoperatively. Nine patients made a full recovery, and 3 had some neurologic deficit on final follow-up. CONCLUSION: Unimodal IONM using SSEP and MEP alone were accurate in diagnosing sensory and motor nerve root injuries, respectively. The diagnostic accuracy in predicting motor and sensory nerve injuries in pediatric HGS improved further with the use of multimodal IONM (combining MEP and SEP). We recommend the utilization of multimodal IONM in all HGS PSF surgeries.

A comparison of three- and two-rod constructs in the correction of severe pediatric scoliosis.

Purpose: Managing severe scoliosis is challenging and risky with a significant complication rate regardless of treatment strategy. In this retrospective comparative study, we report our results using a three-rod compared to two-rod construct in the surgical treatment of severe spine deformities to investigate which technique is safer, and which provides superior radiological outcomes. Methods: Forty-six consecutive patients undergoing posterior spine fusion for scoliosis between 2006 and 2017 were identified in our institutional records. Inclusion criteria were minimum coronal deformity of 90°, age < 18 years at the time of surgery and a minimum 2 years of follow-up. Radiographic and clinical parameters, as well as post-operative complications were compared between the two groups. Results: There were 21 patients in the three-rod group and 25 in the two-rod group. The mean preoperative major coronal deformity was 100°± 9 and 102°± 10 in the three-rod and two-rod, respectively (p = 0.6). The average major curve correction was 51% and 59% in three-rod and two-rod groups, respectively (p = 0.03). The post-operative thoracic kyphosis was 30°± 11 and 21°± 12 in the three-rod and the two-rod groups, respectively (p = 0.01). The surgical time was 476 ± 52 and 387 ± 84 min in three-rod and two-rod, respectively (p < 0.01). One patient in the two-rod cohort showed permanent post-operative sensory deficit. There were three unplanned returns to operating theater in the two-rod group. Conclusions: Coronal correction was better with two-rod, whereas sagittal balance was superior with three-rod. Both techniques achieved balanced spine treating severe scoliosis. The two-rod technique was associated with a higher likelihood of requiring revision surgery. Level of evidence: level 3.

Congenital cervicothoracic dissociation: report of two cases.

PURPOSE: Congenital cervicothoracic dissociation (CCTD) of the spine is a rare condition while having major impacts on stability and neurological function. Surgical treatment includes decompression and instrumented fusion. Only few cases of CCTD have been reported in children. This report intends to demonstrate the complexity of this condition and its surgical management options based on two cases. METHODS: Retrospective illustration of two cases with CCTD treated with instrumented occipito-thoracic fusion. Timing and options of surgical management are discussed. RESULTS: Two patients aged 9 and 12 were treated. Patient 1 presented with asymmetric chronic weakness of the upper extremity and unstable neurogenic bladder. Imaging showed a CCTD with severe distortion of the posterior facets and a dysplastic spinal cord. Patient 2 presented with mild spasticity and unilateral weakness of the upper extremity. A low energy trauma resulted in tetraplegia by increasing the amount of antero-posterior displacement. Both patients were treated with Halo vest application, followed by posterior decompression, and instrumented occipito-thoracic fusion. Additional upfront Halo traction was applied in patient 2 for distraction and sagittal alignment improvement. The last follow-up confirmed solid fusion and minor residual neurological impairment in both patients at 5, and 6 years, respectively. CONCLUSION: CCTD is a rare congenital condition, which can be successfully managed by posterior instrumented fusion. A sudden cervicothoracic displacement with neurological deterioration may respond to careful Halo traction with preoperative sagittal alignment correction. Timing of surgery depends on the actual instability in neurologically stable patients.

Increased proximal vertebral rotation is associated with shoulder imbalance after posterior spinal fusion for severe adolescent idiopathic scoliosis.

PURPOSE: Residual shoulder imbalance is associated with suboptimal outcomes following the surgical correction of adolescent idiopathic scoliosis (AIS) including poor patient satisfaction. In this retrospective study, we evaluate the radiographic parameters and the relationship between the global and local indices of spinal alignment with shoulder balance pre- and postoperatively utilizing EOS imaging and 3D reconstruction. METHODS: A retrospective radiographic analysis was performed on patients with AIS, treated with posterior spinal fusion. Postoperative radiographs were obtained immediately following surgery, at 6 months and final follow-up over 2 years postoperatively. 3D Radiographic measurements included in the coronal plane radiographic shoulder height difference (RSHD), proximal thoracic Cobb angle (PT) and main thoracic Cobb (MT), in the sagittal plane T4-T12 kyphosis, T12-L5 lordosis, in the axial plane proximal thoracic (PT AVR) and main thoracic apical vertebral rotation (MT AVR). RESULTS: Sixty-six patients were included (63 females) with an average main thoracic curvature of 76 degrees. RSHD averaged 14 mm ± 14 preoperatively, -15 mm ± 12 postoperatively, -8.5 mm ± 11 at 6 months, and -8.3 mm ± 8.7 at final follow-up, respectively. Statistical analysis revealed a significant correlation between RSHD and proximal thoracic Cobb angle, between RSHD and proximal thoracic apical vertebral rotation (PTAVR) (r > 0.20, p < 0.05). CONCLUSION: The significant correlation presented in this study suggests that PT Cobb angle and PT AVR are involved in postoperative shoulder imbalance. THE LEVEL OF EVIDENCE: Level 4.

Implant-Related Complications Using Uniaxial Implants In Pediatric Spinal Deformity Surgery.

INTRODUCTION:  The successful surgical treatment of paediatric spinal deformity relies on robust anchors to achieve correction. Uniaxial pedicle screws are designed with articulation between the screw head and screw shaft, thus reducing the risk of anchor failure whilst permitting corrective manoeuvres. The purpose of this study was to describe the incidence, nature, and chronology of implant-related complications in pediatric spinal deformity treated with uniaxial pedicle screws. METHODS: A retrospective radiographic analysis was carried out on paediatric patients treated for spinal deformity with more than two years of follow-up. Each was treated with posterior instrumented spinal fusion (PISF) using a uniaxial pedicle screw system by a single surgeon at a single institution. Surgical records, post-operative radiographs, and follow-up documentation were scrutinised for details of the implants used, implant failure, and revision procedures. RESULTS: Three hundred and eighty-nine eligible patients with a mean follow-up of 3.3 years were identified. The mean anchor density was 1.7. Seven implant complications were observed. Early complications (<12 months) occurred in four cases and late (>12 months) in three cases. None of the early complications were associated with non-union. Two early and two late complications required revision surgery to manage implant failure and non-union. Patients who underwent fusion across the lumbosacral junction showed a higher than expected rate of implant-related complication (P=0.02). CONCLUSION:  This study shows that there is a rate of implant-related failure of 1.8% after PISF with uniaxial implants in pediatric spinal deformities. There is a distinction between early and late implant-related complications, with early failure being due to loss of construct integrity, whereas late failure is due to pseudarthrosis and construct fatigue.

Correcting Scoliosis in Rett Syndrome.

Objectives Rett syndrome is a rare disorder characterised by severe scoliosis in 80% of cases. In this retrospective case series, we analysed the radiographic, clinical, and functional outcomes of consecutive patients treated for scoliosis associated with Rett syndrome. We sought to understand the results of the treatment of scoliosis in Rett syndrome and evaluate the need to fuse to the pelvis. Methods A retrospective case series was used to analyse the radiographic, clinical, and functional outcomes of consecutive patients treated for Rett syndrome scoliosis between the ages of 10 and 8 years in a single tertiary paediatric spinal unit. Cases were identified through departmental and neurophysiological records, and patients were excluded if the diagnosis of Rett syndrome was not confirmed. Results Seven eligible cases were identified. At presentation, the mean coronal Cobb angle was 90.9°, mean sagittal Cobb 72.0°, and pelvic obliquity 24.5°. The mean post-operative improvement in coronal Cobb was 53.2° and pelvic obliquity reduced to 5.8°. These did not change during a mean follow up of 3.5 years. None showed any post-operative complications. Three patients with a mean 16.1° pelvic obliquity underwent a fusion to L5. The postoperative result in those cases remained stable at 3.5 years mean follow-up and full skeletal maturity. Conclusion Our data suggests that with modern technology, severe curves can be safely treated. Fusion to the pelvis is not necessary in patients with mild, flexible pelvic obliquity.

The Use of Halo Gravity Traction in Severe, Stiff Scoliosis.

PURPOSE: The correction of severe, stiff scoliosis in children is challenging. One method used to reduce the risk is preoperative halo gravity traction (HGT). In this study, the authors sought to define the efficiency and safety of HGT and characterize the chronology of the correction seen. METHOD: A consecutive group of pediatric patients with severe spinal deformities was treated with HGT before definitive correction. A standard protocol with the daily addition of weight to 50% of body weight at 3 weeks was used. Traction remained in place until signs of impending neurological complication or 6 weeks, whichever was sooner. RESULTS: Twenty-four patients were included with a mean age of 11.8 years. The mean coronal deformity was 123 degrees, with a T1-L5 height of 234 mm. The mean duration of traction was 42 days with a mean improvement in height of 72 mm with 82% occurring over the first 3 weeks. Hundred percent of the angular and 98% of T1-L5 height correction was reached by 6 weeks.One patient showed early signs of a cranial nerve palsy prompting early surgery and 8 patients showed pin loosening, 1 of which required revision of their halo. One patient underwent a slower progression of traction because of transitory urinary disturbance. Following fusion, angular correction of the major curve was 49%. CONCLUSION: HGT is a safe treatment for severe, stiff scoliosis because it can respond to early signs of impending neurological impairment. The first 3 weeks of treatment, reaching 50% of body weight as a traction force accounts for 80% of correction, with the remaining 20% in the following 2 weeks. At least 4 weeks of traction is recommended when following this protocol.

The use of three rods in correcting severe scoliosis.

PURPOSE: The three-rod technique, utilising a short apical concavity rod is an option to achieve controlled correction in severe scoliosis. We describe this technique, the complications encountered, and the long-term outcomes. METHOD: All paediatric patients who had at least 2 years follow-up after undergoing corrective surgery for scoliosis ≥ 100° using 3 parallel rods were included. Radiographs were assessed to evaluate the correction and clinical records examined for any loss of correction, complications, revision procedures or neuromonitoring events. RESULTS: Twenty-five patients met the inclusion criteria. Four underwent prior anterior fusion to prevent crankshaft phenomenon. The mean angle of the deformity was 112.0° (range 100.3-137.1). Mean maximal kyphosis was 48.8° (range 11.4-78.8°) and mean curve flexibility 4.4% (range 0-37.0%). Intraoperative traction achieved an average of 70.4% (95% CI 56.6-84.1%). Nine patients (39%) showed a reduction in MEPs during definitive surgery. All returned to within 75% of baseline by the end of surgery. All patients had normal postoperative neurology. One patient underwent removal of hardware for late infection. The mean overall Cobb correction was 55.7° (95% CI 50.2-61.2°), equating to 50.2% (95% CI 44.9-55.4%) of the mean initial deformity. Thoracic kyphosis reduced by a mean of 18.2° (95% CI 12.8-23.6°). CONCLUSION: Our series suggests that three-rod constructs are able to safely and effectively achieve 50% correction of severe scoliosis.

Congenital Kyphosis: Progressive Correction With an Instrumented Posterior Epiphysiodesis: A Preliminary Report.

PURPOSE: Congenital kyphosis is a rare condition. In this case series we sought to identify the outcomes and complications of posterior instrumented fusion and the resultant epiphysiodesis effect in uniplanar congenital kyphosis in pediatric patients. METHOD: Pediatric patients were included if treated for a uniplanar congenital kyphotic deformity treated with posterior instrumented spinal fusion between October 2006 and August 2017, with a minimum of 2 years of follow-up. Patients were excluded if a coronal deformity >10 degrees was present. RESULTS: Six patients met the inclusion criteria. Mean age at surgery was 3.6 years. The mean kyphotic deformity before surgery was 49.7 degrees. All patients underwent posterior instrumented fusion with autogenous iliac crest graft and a cast or brace postoperatively. One patient showed a loss of motor evoked potential on prone positioning which returned to normal on supine positioning. No patient showed any postoperative neurological deficits. One patient was diagnosed with a wound infection which was successfully treated with oral antibiotics.By a follow-up of 5.4 years (range, 2.2 to 10.9 y) there was no failure of instrumentation. An epiphysiodesis effect (a difference of ≥5 degrees in the kyphotic deformity measured between the immediate postoperative and final follow-up lateral whole spine XR) of 16.2 degrees (range, 7.2 to 30.9 degrees) was seen in 5 patients. The mean annual epiphysiodesis effect was 2.7 degrees (95% confidence interval, 1.4-4.1 degrees). No kyphosis proximal to the instrumentation was observed for the duration of follow-up. CONCLUSION: Posterior instrumented fusion and epiphysiodesis is safe and effective. The epiphysiodesis effect occurs in 5/6 of cases, and our data suggests that the procedure is associated with an acceptable blood loss and a low incidence of neurological complications.

Adolescent idiopathic scoliosis detection and referral trends: impact treatment options.

STUDY DESIGN: Retrospective cross-sectional study. OBJECTIVE: To analyze the patient demographic referred for scoliosis to the Hospital for Sick Children to determine the proportion of patients suitable for brace treatment, as per the Scoliosis Research Society guidelines. There is level 1 evidence that bracing in adolescent idiopathic scoliosis (AIS) decreases the risk of curve progression and need for surgery, but optimal brace treatment requires early curve detection. METHODS: We performed a retrospective review of 618 consecutive patients who underwent initial assessment in our Spine Clinic between Jan. 1 and Dec. 31, 2014. We included children 10-18 years, with scoliosis greater than 10°, excluding those diagnosed with non-idiopathic curves. Primary outcomes were Cobb angle, menarchal status, and Risser score. We analyzed the effect of specific referral variables (family history, the person who first noticed the curve, and geographic location of residence) on presenting curve magnitude. RESULTS: During the study period, 335 children met the inclusion criteria, with an average age of 14.1 ± 1.8 years and a mean Cobb angle of 36.8 ± 14.5°. Brace treatment was indicated in 17% of patients; 18% had curves beyond optimal curve range for bracing (> 40°), and 55% were skeletally mature, therefore not brace candidates. The majority of curves (54%) were first detected by the patient or family member and averaged 7° more than curves first detected by a physician. A family history of scoliosis made no difference to curve magnitude, nor did geographic location of residence. CONCLUSION: The majority of AIS patients present too late for effective management with bracing. LEVEL OF EVIDENCE: III.

What is the Optimal Surgical Method for Achieving Correction and Avoiding Neurological Complications in Pediatric High-grade Spondylolisthesis?

BACKGROUND: Controversy persists in the treatment of high-grade spondylolisthesis (HGS). Surgery is recommended in patients with intrusive symptoms and evidence debates the competing strategies. This study compares the radiologic outcomes and postoperative complications at a minimum of 2 years follow-up for patients with HGS treated with instrumented fusion with partial reduction (IFIS) with those treated with reduction, decompression, and instrumented fusion (RIF). We hypothesize that IFIS leads to a lower rate of complication and revision surgery than RIF. METHODS: A retrospective comparative methodology was used to analyze consecutive HGS treated surgically between 2006 and 2017. Patients diagnosed with ≥grade 3 spondylolisthesis treated with arthrodesis before the age of 18 years with a minimum of 2 years follow-up were included. Patients were excluded if surgery did not aim to achieve arthrodesis or was a revision procedure. Cases were identified through departmental and neurophysiological records. RESULTS: Thirty patients met the inclusion criteria. Mean follow-up was 4 years. Ten patients underwent IFIS and the remaining 20 underwent RIF. The 2 groups showed no difference in demographics, grade of slip, deformity or presenting symptoms. Of 10 treated with IFIS, the SA reduced by a mean of 10 degrees and C7 sagittal vertical line changed by 31 mm. In the RIF cohort, SA reduced by 16 degrees and C7 sagittal vertical line reduced by 26 mm. PT was unchanged in both groups. In IFIS cohort, 2 patients showed postoperative weakness, resolved by 2 years. None required revision surgery. In the RIF group, 4 sustained dural tears and 1 a laminar fracture, 7 showed postoperative weakness or dysaesthesia, 3 of which had not resolved by 2 years. Eight patients underwent unplanned further surgery, 3 for pseudarthrosis. CONCLUSIONS: RIF and IFIS show similar radiologic outcomes. RIF shows a higher rate of unplanned return to surgery, pseudarthrosis and persisting neurological changes. LEVEL OF EVIDENCE: Level III-retrospective comparative study.

Impact of Various Weights in the Intraoperative Skull-Skeletal Traction on Correction of Adolescent Idiopathic Scoliosis.

STUDY DESIGN: A retrospective study. OBJECTIVES: Intraoperative skull-skeletal traction (ISST) facilitates the surgical scoliosis correction, but it is also associated with neurological risk. The objective of the present study was to investigate the impact of various traction weights on neurophysiological change and curve correction in surgery for adolescent idiopathic scoliosis (AIS). METHODS: A retrospective review of a consecutive series of posterior spinal fusions for AIS patients undergoing corrections with the use of ISST by 2 surgeons in one institution was performed. Intraoperative prone, post-traction radiographs were performed on all cases. The cases were divided into 2 groups, high and low traction weights, based on whether the weight used was ≥35% or <35% of body weight. The frequency of neurophysiological changes and the curve correction were compared between the 2 groups. RESULTS: The intraoperative correction magnitudes by ISST were significantly larger in the high ISST group than in the low ISST group (35° vs 26°, P < .001). Changes in motor-evoked potential (MEP) were more frequently observed in the high ISST group (47% vs 26%, P = .049). A multivariate analysis showed that high ISST was associated with 3 times higher risk of MEP change (95% confidence interval = 1.1-8.0, P = .03) and higher final postoperative correction rates (68% vs 60%, P = .001). CONCLUSIONS: The high ISST for AIS was associated with increased intraoperative and ultimate curve corrections, and potentially facilitated better final correction. However, the high weight group was associated with an increased frequency of intraoperative MEP changes.

Postoperative Distal Coronal Decompensation After Fusion to L3 for Adolescent Idiopathic Scoliosis Is Affected by Sagittal Pelvic Parameters.

STUDY DESIGN: Retrospective study. OBJECTIVE: To identify on early postoperative radiographs the risk factors for late distal decompensation in adolescent idiopathic scoliosis (AIS) patients undergoing posterior fusion surgery to L3. SUMMARY OF BACKGROUND DATA: Sparing distal fusion levels in AIS surgery is considered beneficial for postoperative mobility and outcomes; nonetheless, late distal decompensation is of concern. L3 is often advocated as lower instrumented vertebra in posterior fusion, but progressive angulation of the L3/4 disc is commonly observed. METHODS: A retrospective analysis was conducted on 78 AIS patients who underwent posterior fusion to L3 from 2007 to 2014. Patients' demographic data, early and 2-year postoperative standing radiographs by biplanar imaging system were investigated. Late decompensation was defined as progressive increase of L3-4 disc wedging angle at 2-year follow-up. Coronal, sagittal, and rotational radiographic parameters were compared between those with and without decompensation. SRS-30 scores were reviewed. RESULTS: Mean age was 14.5-year, and fusion levels averaged 12.0 (range: 6-15); 43 out of 78 patients (55%) experienced progressive L3-4 disc wedging, with 6 showing wedging >5°. L3 translation from the central sacral vertical line (13.9 vs. 11.1 mm, P = 0.13) and increased pelvic tilt (13.3° vs. 8.6°, P = 0.06) on the early postoperative radiograph were associated with increased L3-4 disc wedging. Multivariate analysis revealed that larger pelvic tilt was a significant risk factor for decompensation (odds ratio = 1.1 per 1°, 95% confidence interval: 1.0-1.1, P = 0.04). SRS-30 scores did not differ significantly between the two groups (4.0 vs. 4.1, P = 0.44). CONCLUSIONS: Pelvic retroversion and increased translation of L3 from the central sacral line on the early postoperative radiograph were associated with late L3-4 disc wedging in AIS fusions to L3. Careful surgical planning and correction of sagittal alignment are imperative to ensure the long-term outcomes. LEVEL OF EVIDENCE: 4.

Spinal Casting for the Treatment of Severe Early Onset Scoliosis: Utilization of a Nonsurgical Health Care Provider for Cast Application.

BACKGROUND: Spinal casting with the aim of delaying surgical intervention is a widely accepted but resource intensive conservative management strategy used by spine surgeons to treat severe early onset scoliosis. Opting to use a nonsurgical health care provider for cast application may be an effective use of human resources if the quality of care is not compromised. This study aimed to evaluate the outcomes of spinal cast treatment utilizing a nonsurgical health care provider for cast application. METHODS: This is a chart and radiographic review of all 30 patients that initiated spinal cast treatment between 2007 and 2018 and have at least 2-year follow-up. A spine surgeon applied all casts before July 14; a physical therapist (PT) applied all subsequent casts. Comparative analyses were performed for baseline data and the amount of correction achieved in initial cast. Complications and delay time to surgery were recorded. RESULTS: The PT cast 16 patients (12 female, 10 idiopathic, 64 casts total), average age 3.8±1.4 years and mean major curve of 63±18 degrees. Similarly the spine surgeon cast 14 patients (11 female, 8 idiopathic, 53 casts total), average age 4.4±1.7 years (P=0.30) and mean major curve of 63±11 degrees (P=0.93). In the initial cast the PT obtained 55%±13% (28±12 degrees) correction and the surgeon 44%±12% (36±12 degrees, P=0.09). The average number of casts was similar (4.0 vs. 3.8, P=0.7). The PT had 1 patient develop superior mesenteric artery syndrome, which resolved with cast removal, and the surgeon had 2 patients require extra care related to skin breakdown. With average follow-up of 4.15 years (range, 2.0 to 5.8 y) 11/14 PT patients demonstrate curve improvement compared with their initial presentation and 2 patients have undergone surgical intervention (3.2 and 4.3 y after first cast). The surgeon's average delay time to surgery was 4.3 years (range, 1.8 to 8.7 y after first cast, n=10). CONCLUSIONS: The results of this study support our current model of care utilizing a nonsurgical health care practitioner for spinal cast application. LEVEL OF EVIDENCE: Level III-retrospective comparative.

Klippel Feil Syndrome: Clinical Phenotypes Associated With Surgical Treatment.

STUDY DESIGN: Retrospective study. OBJECTIVE: To define distinct Klippel-Feil syndrome (KFS) patient phenotypes that are associated with the need for surgical intervention. SUMMARY OF BACKGROUND DATA: KFS is characterized by the congenital fusion of cervical vertebrae; however, patients often present with a variety of other spinal and extraspinal anomalies suggesting this syndrome encompasses a heterogeneous patient population. Moreover, it remains unclear how the abnormalities seen in KFS correlate to neurological outcomes and the need for surgical intervention. METHODS: Principal component (PC) analysis was performed on 132 KFS patients treated at a large pediatric hospital between 1981 and 2018. Thirty-five variables pertaining to patient/disease-related factors were examined. Significant PCs were included as independent variables in multivariable logistic regression models designed to test associations with three primary outcomes: cervical spine surgery, thoracolumbar/sacral spine surgery, and cranial surgery. RESULTS: Fourteen significant PCs accounting for 70% of the variance were identified. Five components, representing four distinct phenotypes, were significantly associated with surgical intervention. The first group consisted of predominantly subaxial cervical spine fusions, thoracic spine abnormalities and was associated with thoracolumbar/sacral spine surgery. The second group was largely represented by axial cervical spine anomalies and had high association with cervical subluxation and cervical spine surgery. A third group, heavily represented by Chiari malformation, was associated with cranial surgery. Lastly, a fourth group was defined by thoracic vertebral anomalies and associations with sacral agenesis and scoliosis. This phenotype was associated with thoracolumbar/sacral spine surgery. CONCLUSION: This is the first data-driven analysis designed to relate KFS patient phenotypes to surgical intervention and provides important insight that may inform targeted follow-up regimens and surgical decision-making. LEVEL OF EVIDENCE: 3.

Responding to Intraoperative Neuromonitoring Changes During Pediatric Coronal Spinal Deformity Surgery.

STUDY DESIGN: Retrospective case study on prospectively collected data. OBJECTIVES: The purpose of this explorative study was: 1) to determine if patterns of spinal cord injury could be detected through intra-operative neuromonitoring (IONM) changes in pediatric patients undergoing spinal deformity corrections, 2) to identify if perfusion based or direct trauma causes of IONM changes could be distinguished, 3) to observe the effects of the interventions performed in response to these events, and 4) to attempt to identify different treatment algorithms for the different causes of IONM alerts. METHODS: Prospectively collected neuromonitoring data in pre-established forms on consecutive pediatric patients undergoing coronal spinal deformity surgery at a single center was reviewed. Real-time data was collected on IONM alerts with >50% loss in signal. Patients with alerts were divided into 2 groups: unilateral changes (direct cord trauma), and bilateral MEP changes (cord perfusion deficits). RESULTS: A total of 97 pediatric patients involving 71 females and 26 males with a mean age of 14.9 (11-18) years were included in this study. There were 39 alerts in 27 patients (27.8% overall incidence). All bilateral changes responded to a combination of transfusion, increasing blood pressure, and rod removal. Unilateral changes as a result of direct trauma, mainly during laminotomies for osteotomies, improved with removal of the causative agent. Following corrective actions in response to the alerts, all cases were completed as planned. Signal returned to near baseline in 20/27 patients at closure, with no new neurological deficits in this series. CONCLUSION: A high incidence of alerts occurred in this series of cases. Dividing IONM changes into perfusion-based vs direct trauma directed treatment to the offending cause, allowing for safe corrections of the deformities. Patients did not need to recover IONM signal to baseline to have a normal neurological examination.

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.

Three-dimensional EOS Analysis of Apical Vertebral Rotation in Adolescent Idiopathic Scoliosis.

BACKGROUND: Apical vertebral rotation (AVR) is increasingly recognized as one of the important radiographic parameters in adolescent idiopathic scoliosis (AIS). EOS enables us to precisely measure AVR by 3-dimensional reconstruction. The objective of the present study was to describe the postoperative correction and the long-term follow-up of AVR in posterior spinal fusion with direct vertebral rotation and elucidate the factors that affected the correction. METHODS: We retrospectively reviewed 153 consecutive posterior spinal fusion surgeries for AIS performed between 2009 and 2012. Among them, 55 patients who fulfilled the study inclusion criteria with complete preoperative, immediate postoperative, and last follow-up (>1 y) EOS images were included in the present study. EOS 3-dimentional reconstructions were undertaken for each patient. Postoperative AVR correction and the loss of correction were calculated. RESULTS: Preoperative AVR of the major curve averaged 19 degrees (SD=7 degrees), and AVR on immediate postoperative images averaged 9 degrees (SD=6 degrees, P<0.001). AVR at final follow-up averaged 11 degrees (SD=6 degrees, P=0.06). Postoperative correction was larger in all-screw construct than in hybrid construct (55% vs. 36%, P=0.03). CONCLUSIONS: The present study is the first study to measure AVR in a large population of AIS patients using EOS 3-dimensional reconstruction. We report the correction magnitude was significantly affected by the construct. LEVEL OF EVIDENCE: Level IV-therapeutic study (case series).

The "slide technique": an improvement on the "funnel technique" for safe pedicle screw placement in the thoracic spine.

STUDY DESIGN: Technical note. OBJECTIVES: To report and describe a new free-hand technique for pedicle screw placement in the thoracic spine especially in severe deformities. Because of distortion of anatomic landmarks scoliosis, this free-hand placement technique based on pedicle access through the decancelled transverse process is a safe procedure. METHODS: Transverse process is widely exposed and its posterior cortex is decorticated. The cancellous bone content of the transverse process is completely removed using a small curette. Bone wax is applied to avoid local bleeding and then the decancelled transverse process is inspected. The entry of the pedicle is then easily identified by the presence of remaining cancellous bone. A pedicular probe is then inserted and gently advanced. During pedicle probe insertion, the cortex of the anterior aspect of transverse process and the lateral margin of the pedicle act as a "slide" to permit safe insertion of the instrument. RESULTS: In our experience, no patient required additional procedures for screw revision, and no neurologic deficit occurred stemming from malpositioning of pedicle screws. The key point of the "slide technique" is to use the cortex of the anterior aspect of transverse process and the lateral margin of the pedicle as a "slide" to permit correct probe positioning during pedicle probe insertion. CONCLUSIONS: This technique is very close to the "funnel technique". The "funnel" and then the "slide" technique are mostly useful in complex spinal deformities as in neuromuscular patients. The "slide technique" is a safe, effective and cost-effective technique for pedicle screw placement in the thoracic spine especially in severe deformities. LEVEL OF EVIDENCE: IV.