Prediction Model for Lumbar Curve Correction after Selective Thoracic Fusion in Lenke 1 and 2 Adolescent Idiopathic Scoliosis.

STUDY DESIGN: A retrospective study. OBJECTIVE: To identify independent risk factors and construct a prediction model for lumbar curve correction (LCC) after selective thoracic fusion (STF) in patients with Lenke 1 and 2 adolescent idiopathic scoliosis (AIS). SUMMARY OF BACKGROUND DATA: STF has been widely applied in Lenke 1 and 2 AIS patients. However, LCC after STF is still controversial. METHODS: 128 patients undergoing STF with at least 2 years follow-up were included. Cases were divided into high-LCC group and low-LCC group according to a rounded-up median of 65%. 49 variables were taken into account. Logistic regression was applied to identify independent predictive factors. Prediction model was established by backward stepwise regression, and its evaluation was implemented on R. RESULTS: Five parameters showed independent predictive value for low LCC: Right shoulder higher before surgery [right shoulder higher vs. balanced: odds ratio (OR)=0.244, P=0.014], postoperative Cobb angle of lumbar curve (LC) (OR=1.415, P=0.001, cut-off value=11°), lowest instrumented vertebra (LIV) distal to end vertebra (no vs. yes: OR=4.587, P=0.013), postoperative LIV tilt (OR=0.686, P=0.010, cut-off value=6.85°) and postoperative LIV+1 tilt (OR=1.522, P=0.005, cut-off value=6.25°). The prediction model included six variables: lumbar modifier, preoperative shoulder balance, postoperative Cobb angle of LC, LIV position, postoperative LIV tilt and postoperative LIV+1 tilt. Model evaluation demonstrated satisfactory capability and stability [area under curve=0.890, 10-fold cross-validation accuracy=0.782]. CONCLUSION: Preoperative shoulder balance, Cobb angle of LC, LIV position, postoperative LIV and LIV+1 tilt could be used to prognosticate LCC after STF. A model with solid prediction ability was established, which could further our understanding of LCC and assist in making clinical decisions.

Posterior Corrective Surgery for Type II Congenital Kyphosis: SRS-Schwab Grade 4 Osteotomy or Vertebral Column Resection?

OBJECTIVE: Surgical decision-making for congenital kyphosis (CK) with failure of anterior segmentation (type II) has been contradictory regarding the trade-off between the pursuit of correction rate and the inherent risk of the osteotomy procedure. This study was designed to compare the clinical and radiographic measurement in type II CK underwent SRS-Schwab Grade 4 osteotomy and vertebral column resection (VCR), the most-adapted osteotomy techniques for CK, and to propose the strategy to select between the two procedures. METHODS: This retrospective observational comparative study evaluated surgical outcomes in type II CK patients underwent VCR or SRS-Schwab Grade 4 osteotomy at our institution between January 2015 and January 2020. Patients operated with VCR and SRS-Schwab Grade 4 osteotomy were allocated to Group 1 and Group 2 respectively. Radiographic parameters and SRS-22 quality of life metrics were assessed at pre-operation, post-operation, and during follow-up visits for both groups, allowing for a comprehensive comparison of surgical outcomes. RESULTS: Thirty-one patients (19 patients in Group 1 and 12 patients in Group 2) aged 16.3 ± 10.4 years were recruited. Correction of segmental kyphosis was similar between groups (51.1 ± 17.6° in Group 1 and 48.4 ± 19.8° in Group 2, p = 0.694). Group 1 had significantly longer operation time (365.9 ± 81.2 vs 221.4 ± 78.9, p < 0.001) and more estimated blood loss (975.2 ± 275.8 ml vs 725.9 ± 204.3 mL, p = 0.011). Alert event of intraoperative sensory and motor evoked potential (SEP and MEP) monitoring was observed in 1 patient of Group 2. Both groups had 1 transient post operative neurological deficit respectively. CONCLUSION: SRS-Schwab Grade 4 osteotomy was suitable for kyphotic mass when its apex is the upper unsegmented vertebrae or the neighboring disc, or when the apical vertebrae with an anterior/posterior (A/P) height ratio of vertebral body higher than 1/3. VCR is suitable when the apex is located within the unsegmented mass with its A/P height ratio lower than 1/3. Proper selection of VCR and SRS-Schwab Grade 4 osteotomy according to our strategy, could provide satisfying radiographic and clinical outcomes in type II CK patients during a minimum of 2 years follow-up. Patients undergoing VCR procedure might have longer operation time, more blood loss and higher incidence of peri- and post-operative complications.

Assessing Neurological Complications in Thoracic Three-Column Osteotomy: A Clinical Application of a Novel MRI-Based Classification Approach.

STUDY DESIGN: Retrospective comparative study. OBJECTIVE: To investigate the occurrence of neurological complications in patients undergoing thoracic three-column osteotomy (3CO) utilizing an magnetic resonance imaging (MRI)-based classification that assesses spinal cord shape and the presence of cerebrospinal fluid at the curve apex and evaluate its prognostic capacity for postoperative neurological deficits. SUMMARY OF BACKGROUND DATA: Recent advancements in correction techniques have improved outcomes for severe spinal deformity patients undergoing 3CO. A novel MRI-based spinal cord classification system was introduced, but its validation and association with postoperative complications remain unexplored. MATERIALS AND METHODS: Between September 2012 and September 2018, a retrospective analysis was conducted on 158 adult patients with spinal deformities undergoing 3CO. Radiographic parameters were measured. T2-weighted axial MRI was used to describe spinal cord morphology at the apex. Intraoperative neurophysiological monitoring alerts were recorded, and preoperative and postoperative neurological functions were assessed using the Frankel score. Categorical data were compared using the χ 2 or the Fisher exact test. The paired t test was utilized to assess the mean difference between preoperative and postoperative measurements, while the one-way analysis of variance and independent t test were used for comparative analyses among the different spinal cord types. RESULTS: Patients were categorized into three groups: type 1, type 2, and type 3, consisting of 12, 85, and 61 patients. Patients with type 3 morphology exhibited larger Cobb angles of the main curve ( P <0.001). This disparity persisted both postoperatively and during follow-up ( P <0.05). Intraoperative neurophysiological monitoring alerts were triggered in 32 patients (20.3%), with a distribution of one case in type 1, six cases in type 2, and 22 cases in type 3 morphologies ( P <0.001). New neurological deficits were observed in 15 patients (9.5%), with 1, 3, and 11 cases in type 1, 2, and 3 morphologies, respectively. CONCLUSIONS: Patients with type 3 morphology exhibited greater spinal deformity severity, a higher likelihood of preoperative neurological deficits, and an elevated risk of postoperative neurological complications. This underscores the utility of the classification as a tool for predicting postoperative neurological complications in patients undergoing thoracic 3CO. LEVEL OF EVIDENCE: 4.

Intra-operative Neurophysiological Monitoring in Patients Undergoing Posterior Spinal Correction Surgery with Pre-operative Neurological Deficit: Its Feasibility and High-risk Factors for Failed Monitoring.

OBJECTIVE: Considering spinal deformity patients with pre-operative neurological deficit were associated with more intra-operative iatrogenic neurological complications than those without, intra-operative neurophysiological monitoring (IONM) has been used for detecting possible iatrogenic injury timely. However, the IONM waveforms are often unreliable. To analyze the performance of intra-operative neurophysiological monitoring (IONM) including somatosensory evoked potentials (SEP) and motor evoked potentials (MEP) in patients with pre-operative neurological deficit undergoing posterior spinal correction surgery, and to identify the high-risk factors for failed IONM. METHODS: Patients with pre-operative neurological deficit undergoing posterior spinal correction surgery between October 2017 and January 2022 were retrospectively reviewed. The presence or absence of SEP and MEP of target muscles were separately recorded. The P37/N50 latency and amplitude of SEP, and the MEP amplitude were measured. Any IONM alerts were also recorded. The IONM performance was compared among patients with different etiologies, levels responsible for neurological deficit, and strength of IONM-target muscles. Patients' demographics were analyzed using the descriptive statistics and were presented with mean ± standard deviation. Comparison analysis was performed using χ2 -test and statistically significant difference was defined as p < 0.05. RESULTS: A total of 270 patients (147 males, 123 females) with an average age of 48.4 ± 36.7 years were involved. The SEP records were available in 371 (68.7%) lower extremities while MEP records were available in 418 (77.4%). SEP alerts were reported in 31 lower extremities and MEP alerts in 22, and new neurological deficit at post-operation was observed in 11. The etiologies of neuromuscular and syndromic indicated relatively lower success rates of IONM, which were 44.1% and 40.5% for SEP, and 58.8% and 59.5% for MEP (p < 0.001). In addition, patients with pre-operative neurological deficit caused by cervical spine and muscle strength lower than grade 4 suffered from higher risk of failed IONM waveforms (p < 0.001). CONCLUSION: Patients with pre-operative neurological deficit suffered from a higher incidence of failed IONM results. The high-risk for failed IONM waveforms included the neuromuscular and syndromic etiologies, neurological deficit caused by cervical spine, muscle strength lower than grade 4 in patients with pre-operative neurological deficit undergoing posterior spinal correction surgery.

Hemivertebra resection after age three produces the similar results but with less complications compared to earlier surgery: a minimum of 5-year follow-up.

BACKGROUND: The optimal timing for hemivertebra resection remains controversial. Early intervention before 3 years of age seems being able to get better correction with less fusion segments. However, it was also reported that early surgery may be associated with more complications. The purpose of this study is to investigate correction outcomes and complications of delayed hemivertebra resection (between 3 and 5 years of age), in comparison with earlier surgery (before 3 years of age). METHODS: Patients who had undergone thoracolumbar hemivertebra resection at a single level before 5 years of age and had more than 5 years of follow-up were reviewed. Twenty-four patients had hemivertebra resection surgery below 3 years of age (early surgery, Group E), and 33 patients received surgery between 3 and 5 years of age (delayed surgery, Group D). Radiographs from preoperative, immediately postoperative, and the latest follow-up visits were reviewed to investigate the correction outcomes. Complications were recorded and compared between these two groups. RESULTS: The patients of Group E had shorter operation time and less blood loss than those of Group D (P = 0.003 and P = 0.006). Notably, the fusion segments were 2.3 ± 0.7 and 3.1 ± 1.2 in group E and group D (P = 0.005), respectively, indicating group E averagely saved 0.8 motion segments. At the time of surgery, group E had smaller main curve magnitude either in the coronal or in the sagittal plane than group D and experienced similar correction rates of scoliosis (83.3 ± 21.6% vs. 81.2 ± 20.1%, P = 0.707) and kyphosis (65.1 ± 23.8% vs. 71.7 ± 24.9%, P = 0.319). However, group E had relatively higher complication rates than group D and relatively greater correction loss in either coronal or sagittal plane during follow-up. CONCLUSIONS: Hemivertebra resection resulted in similar correction results in both age groups. However, the rate of complications was lower for Group D than Group E. Thus, for non-kyphotic hemivertebra, surgery may be delayed till 3 to 5 years of age.

How does congenital cervicothoracic scoliosis bring about early trunk tilt and coronal imbalance during curve progression: a radiographic analysis to dissect the mechanism of proximal takeoff phenomenon.

PURPOSE: To dissect the mechanism of how congenital cervicothoracic scoliosis (CTS) drive the occurrence of early trunk tilt, namely proximal takeoff phenomenon (PTO) during curve progression. METHODS: CTS patients were stratified into case and control groups according to the presence of PTO. The radiographic deformity parameters of head-neck-shoulder complex were measured and compared between the two groups. The main risk factors for PTO were identified through multiple linear regression analysis. RESULTS: 16 CTS patients with PTO were recruited, and the non-PTO group consisted of 19 CTS patients without PTO. The average Cobb angle was 64.9 ± 19.8° in PTO group and 57.7 ± 21.9° in control group (p > 0.05). Significant difference could be observed for head shift, neck tilt, trunk inclination, apex-C7 deformity angular ratio (DAR), apex translation ratio, C6 tilt, clavicle angle (CA), radiographic shoulder height (RSH), head-neck translation and coronal balance distance (CBD) (All p < 0.05) but not head tilt (p > 0.05). Multiple linear regression analysis revealed that head shift, but not neck tilt correlated significantly with the severity of trunk inclination (ß = 0.106, p = 0.003), while apex-C7 DAR and apex translation ratio were the two factors contributing significantly to the severity of head shift (ß = 0.620, p = 0.020; ß = - 0.371, p = 0.004). CONCLUSIONS: Development and progression of head shift rather than neck tilt is a significant causative factor initiating the occurrence of trunk tilt and proximal takeoff in CTS. A higher apex-C7 DAR representing a short angular upper hemi curve and a lower apex translation ratio representing poor proximal coronal compensation are key risk factors predisposing to head shift.

Satellite Rod Fixation around Rod-fracture Area in Revision Surgery after Three-column Osteotomy for Severe Kyphoscoliosis.

OBJECTIVE: Three-column osteotomy (3CO) is considered valuable and increasingly utilized in the surgical treatment of severe spine deformity while associated with high implant-related complications and revision risks. This study aims to evaluate the feasibility and clinical outcomes of satellite rod fixation used around the rod-fracture area in revision surgery due to rod fracture after 3CO. METHODS: Twenty-five patients applying satellite rod fixation in revision surgery from August 2012 to May 2016 were retrospectively reviewed as the SR group. Patients undergoing revision surgery with traditional strategy after 3CO due to rod-fracture were selected as the TR group. Cobb angle, distance between C7 plumb line and center sacral vertical line (C7 PL-CSVL), global kyphosis (GK) and sagittal vertical axis (SVA) were assessed. Patients were required to fulfill the Scoliosis Research Society-22 questionnaire (SRS-22) at pre-revision and the last follow-up. The paired t test was used to analyze the difference among pre-revision, post-revision and last follow-up. RESULTS: There was no statistical difference in terms of age, gender, body mass index (BMI), fusion level at 1st surgery, and follow-up period between SR and TR group (all P > 0.05). The operation time (1.5 ± 0.7 h vs 3.2 ± 0.9 h, P < 0.001) and intraoperative blood loss (178 ± 51 mL vs 324 ± 96 mL, P < 0.001) were significantly higher in the TR group. Patients in both groups obtained obvious deformity correction after revision surgery. For patients in SR group, the coronal Cobb angle significantly improved from 27.9 ± 21.5° at pre-revision to 21.8 ± 16.6° at post-revision (P = 0.034). The C7 PL-CSVL decreased from 22.6 ± 14.3 mm to 21.3 ± 10.9 mm (P = 0.719). Similarly, improvement was attained in post-revision GK (25.8 ± 17.0° vs 20.2 ± 15.1°, P = 0.061). SVA was corrected from 35.6 ± 33.9 mm to 30.8 ± 24.3 mm after revision (P = 0.182). At the last follow-up, no significant correction loss was observed in both coronal and sagittal parameters (all P > 0.05). All patients responded to the SRS-22 questionnaire and all the domains showed improvements in different levels. As compared to the TR group, the SR group had significantly better pain and management satisfaction scores (all P < 0.05). Additionally, there was no reoccurrence of implant failure during follow-up and all patients achieved solid bony fusion in SR group. CONCLUSION: Satellite rod fixation around rod-fracture area is indicated for patients in the requirement of revision surgeries due to rod fracture after 3CO. Compared with traditional revision strategies, revision surgery with satellite rods, if patients are selected adequately, is a simpler procedure with less intraoperative blood loss and shorter operating time.

Intra-Operative Neurophysiological Monitoring in Patients with Thoracic Spinal Stenosis: Its Feasibility and High-Risk Factors for New Neurological Deficit.

OBJECTIVE: Considering the high risk of postoperative neurological complications for patients with thoracic spinal stenosis (TSS), intra-operative neurophysiological monitoring (IONM) has been used for detecting possible iatrogenic injury timely. However, the IONM waveforms are often unreliable. This article is designed to determine the test performance of somatosensory evoked potentials (SEP) and motor evoked potentials (MEP) during surgical thoracic decompression in patients with TSS, and to investigate the risk factors associated with deteriorated neurologic function at immediate postoperation. METHODS: Patients undergoing posterior spinal fusion from February 2009 to December 2020 were retrospectively reviewed. Patients were divided into the deteriorated neurologic function (DNF) group and the improved/intact neurological function (INF) group based on the postoperative neurological status. Demographic parameters such as gender, age, height, weight, etiology and IONM data were compared between groups. Demographics and IONM data between DNF and INF groups were compared by independent t or nonparametric tests. The incidence of abnormal SEP was analyzed by Chi-square test. RESULTS: A total of 108 patients (63 males, 45 females) with an average age of 53.5 ± 14.0 years were included. The SEP and MEP records were available in 94 and 98 patients, with the overall success rates being 87.0% and 90.7%, respectively. The sensibilities and specificities were 100% and 88.2% for SEP, 100% and 98.8% for MEP, respectively. There were 17 patients in DNF group and 91 patients in INF group. High weight (79.1 ± 14.6 vs 69.7 ± 15.7 kg, P = 0.024), high inter-side difference of MEP amplitude (899.1 ± 997.5 vs 492.3 ± 512.4 µV, P = 0.013) and high incidence of abnormal SEP (94.1% vs 64.8%, P = 0.024) were observed in the DNF group. Fourteen (82.4%) patients in the DNF group showed improvement in neurological status during follow-up. CONCLUSIONS: The overall success rates were 87.0% for SEP and 90.7% for MEP in patients with TSS.

ROS-Scavenging Hydrogels Synergize with Neural Stem Cells to Enhance Spinal Cord Injury Repair via Regulating Microenvironment and Facilitating Nerve Regeneration.

Although stem cell-based therapy is recognized as a promising therapeutic strategy for spinal cord injury (SCI), its efficacy is greatly limited by local reactive oxygen species (ROS)-abundant and hyper-inflammatory microenvironments. It is still a challenge to develop bioactive scaffolds with outstanding antioxidant capacity for neural stem cells (NSCs) transplantation. In this study, albumin biomimetic cerium oxide nanoparticles (CeO2 @BSA nanoparticles, CeNPs) are prepared in a simple and efficient manner and dispersed in gelatin methacryloyl to obtain the ROS-scavenging hydrogel (CeNP-Gel). CeNP-Gel synergistically promotes neurogenesis via alleviating oxidative stress microenvironments and improving the viability of encapsulated NSCs. More interestingly, in the presence of CeNP-Gel, microglial polarization to anti-inflammatory M2 subtype are obviously facilitated, which is further verified to be associated with phosphoinositide 3-kinase/protein kinase B pathway activation. Additionally, the injectable ROS-scavenging hydrogel is confirmed to induce the integration and neural differentiation of transplanted NSCs. Compared with the blank-gel group, the survival rate of NSCs in CeNP-Gel group is about 3.5 times higher, and the neural differentiation efficiency is about 2.1 times higher. Therefore, the NSCs-laden ROS-scavenging hydrogel represents a comprehensive strategy with great application prospect for the treatment of SCI through comprehensively modulating the adverse microenvironment.

Posterior-only correction surgery for idiopathic scoliosis Lenke type 5c: differences of strategies and outcomes between adult patients and adolescent patients.

PURPOSE: To compare radiographic parameters, and functional and surgical outcomes between lumbar adolescent idiopathic scoliosis (AIS) and lumbar adult idiopathic scoliosis (AdIS). METHODS: A retrospective study was performed to identify Lenke 5c type AIS and AdIS patients from our scoliosis database who had undergone posterior surgical treatment for scoliosis. Preoperative and postoperative radiographic and clinical outcomes were compared between the two groups. RESULTS: A total of 22 patients were included in AdIS group, and 44 matched patients in AIS group. AdIS group had significantly larger L3 and L4 tilt and translation than AIS group (P < 0.05). AdIS group had larger T10-L2 angle and smaller T5-T12 angle (P < 0.05). AdIS group had higher VAS scores (P < 0.05) and pain domain of SRS-22 scores (P < 0.05) as compared to AIS group. Correlation analysis demonstrated positive relationship between VAS scores and T10-L2 angle (r = 0.492, P < 0.05). AdIS group was fused longer than AIS group (P < 0.05). Cobb angle of TL/L curve was larger and correction ratio was smaller at AdIS group (P < 0.05). AdIS group still had significantly larger L3 and L4 tilt and translation than AIS group (P < 0.05). CT measurements demonstrated larger postoperative vertebral body rotation at apical vertebrae and LIV at AdIS group (P < 0.05). Vertebral correction ratio was smaller at AdIS group (P < 0.05). CONCLUSION: Lenke 5c AdIS patients had greater preoperative and postoperative L3 and L4 tilt and translation, as well as less correction of major curve and vertebral body derotation than AIS patients. However, the incidence of adding-on was similar between the two groups.

Intraoperative Neurophysiological Monitoring Alerts During Three-Column Osteotomy: Incidence and Risk Factors.

PRUPOSE: To analyze the incidence and risk factors of intraoperative neurophysiological monitoring (IONM) alerts in patients undergoing three-column osteotomy. METHODS: A total of 551 patients (340 males and 211 females) with an average age of 31.9 years undergoing posterior 3-column osteotomy were retrospectively reviewed. The coronal Cobb angle of main curve and sagittal global kyphosis were measured on preoperative standing whole spinal x-rays. The Frankel scores at preoperation, postoperation, and the last follow-up were recorded and applied for assessment of neurologic status. Surgical procedures and other factors associated with IONM alerts were analyzed. RESULTS: A total of 98 (17.8%) IONM alerts were reported during surgery, including 82 somatosensory evoked potential alerts and 91 motor evoked potential alerts. Positive wake-up test was revealed in 57 patients (10.3%) even after prompt managements, and new neurologic deficits were observed in 50 patients (9.1%) at immediate postoperation. Of the 50 patients with new neurologic deficits at postoperation, the Frankel scores were A in 5 patients, B in 4, C in 9, and D in 32. The χ 2 test showed that patients with congenital deformities, global kyphosis >90°, vertebral column resection procedure, cervicothoracic/thoracic osteotomy, blood loss >3,000 mL, and preoperative neurologic deficit were at a higher risk of IONM alerts. CONCLUSIONS: The incidence of IONM alerts in patients undergoing 3-column osteotomy was 17.8%. Congenital deformities, global kyphosis >90°, vertebral column resection, cervicothoracic/thoracic osteotomy, blood loss >3,000 mL, and preoperative neurologic deficit indicated high risk of IONM alerts.

Ultrasound-triggered piezocatalytic composite hydrogels for promoting bacterial-infected wound healing.

Wound healing has become one of the basic issues faced by the medical community because of the susceptibility of skin wounds to bacterial infection. As such, it is highly desired to design a nanocomposite hydrogel with excellent antibacterial activity to achieve high wound closure effectiveness. Here, based on ultrasound-triggered piezocatalytic therapy, a multifunctional hydrogel is designed to promote bacteria-infected wound healing. Under ultrasonic vibration, the surface of barium titanate (BaTiO3, BT) nanoparticles embedded in the hydrogel rapidly generate reactive oxygen species (ROS) owing to the established strong built-in electric field, endowing the hydrogel with superior antibacterial efficacy. This modality shows intriguing advantages over conventional photodynamic therapy, such as prominent soft tissue penetration ability and the avoidance of serious skin phototoxicity after systemic administration of photosensitizers. Moreover, the hydrogel based on N-[tris(hydroxymethyl)methyl]acrylamide (THM), N-(3-aminopropyl)methacrylamide hydrochloride (APMH) and oxidized hyaluronic acid (OHA) exhibits outstanding self-healing and bioadhesive properties able to accelerate full-thickness skin wound healing. Notably, compared with the widely reported mussel-inspired adhesive hydrogels, OHA/THM-APMH hydrogel due to the multiple hydrogen bonds from unique tri-hydroxyl structure overcomes the shortage that catechol groups are easily oxidized, giving it long-term and repeatable adhesion performance. Importantly, this hybrid hydrogel confines BT nanoparticles to wound area and locally induced piezoelectric catalysis under ultrasound to eradicate bacteria, markedly improving the therapeutic biosafety and exhibits great potential for harmless treatment of bacteria-infected tissues.

Failure of Posterior Lower Lumbar/Lumbosacral Hemi-Vertebra Resection: An Analysis of Reasons and Revision Strategies.

OBJECTIVE: To investigate the causes of failed primary surgery and the revision strategies for congenital scoliosis (CS) patients with lower lumbar/lumbosacral (LL/LS) hemi-vertebra (HV). METHODS: Fifteen CS patients with LL/LS HV (seven females and eight males) with a mean age of 20.4 ± 10.4 years undergoing revision surgery in our center were retrospectively reviewed. The radiographic parameters including Cobb angle, distance between C7 plumb line and center sacral vertical line (C7 PL-CSVL), thoracic kyphosis (TK), lumbar lordosis (LL) and sagittal vertical axis (SVA) were assessed at pre-revision, post-revision and the last follow-up. The causes of failure in primary operation, and radiographic and clinical outcomes of revision procedures were analyzed. RESULTS: The revision rate of patients undergoing LL/LS HV resection and correction surgery was 11.4%. The average time interval between primary surgery and revision surgery was 18.2 ± 10.6 months. The operation duration and estimated blood loss of revision surgery were 194 ± 56 min and 326 ± 74 ml, respectively. Reasons for failed primary operations were as follows: internal fixation fracture in 10 cases, curve progression in two cases, implant loose in two cases and post-operative coronal imbalance in one case. The post-revision Cobb angle was significantly improved from 29.9° ± 8.3° to 18.7° ± 6.7° (P < 0.001) with a correction rate of 37.5% ± 12.6%. At the final follow-up, the average Cobb angle was 18.9° ± 6.2° and the correction was well maintained (P = 0.788). The C7 PL-CSVL at pre-revision, post-revision and at last follow-up were 23.2 ± 9.3 mm, 14.8 ± 4.8 mm and 14.9 ± 5.4 mm, respectively. Significant improvements (P = 0.004) were observed after revision surgery and there was no evident loss of correction (P = 0.703). There was no significant difference in TK, LL and SVA before and after revision surgery (all P > 0.05). At the last follow-up, no significant correction loss of above coronal and sagittal parameters were observed (all P > 0.05). The revision methods were individualized according to the primary surgical procedures and the reasons for revision. The recommended revision strategies include incision of pseudarthrosis with sufficient bone graft, fixation of satellite rods, thorough residual HV excision, prolonged fusion to S2 and transforaminal lumbar interbody fusion at lumbosacral region. Solid bony fusion and no implant-related complication were detected during the follow-up. CONCLUSIONS: The causes of revision surgery for patients with congenital scoliosis (CS) due to lumbosacral HV were verified and implant failure with pseudarthrosis was the main reason for failed primary operation.

Intra-Operative Neurophysiological Monitoring in Patients with Intraspinal Abnormalities Undergoing Posterior Spinal Fusion.

OBJECTIVE: To analyze the intraoperative neurophysiological monitoring (IONM) data of patients with intraspinal abnormalities undergoing posterior spinal fusion and to determine how intraspinal abnormalities influence IONM results. METHODS: Patients with severe kyphoscoliosis and intraspinal abnormalities who underwent posterior spinal correction and fusion between September 2015 and January 2019 were retrospectively reviewed. Candidate intraspinal abnormalities included Chiari malformation, syringomyelia, split cord malformation, and tethered cord syndrome. Total intravenous anesthesia was administered, and no muscle relaxant or inhalation anesthesia was used for maintenance. IONM data, including somatosensory evoked potentials (SSEP) and motor evoked potentials (MEP), were recorded. The P37 and N50 latencies and amplitude were recorded for SSEP, whereas only the amplitude was recorded for MEP. The possible high-risk factors for abnormal IONM results were analyzed. RESULTS: The current study included 87 patients (40 men, 47 women) with an average age of 20.2 ± 10.4 years. The etiologies were neuromuscular in 45 patients, idiopathic in four, and congenital in 38. A total of 136 intraspinal abnormalities were detected, including Chiari malformation in 33 patients, syringomyelia in 55, split-cord malformation in 25, and tethered cord syndrome in 23. Forty patients had one intraspinal abnormality, whereas 47 patients had two or three intraspinal abnormalities. The monitorabilities were 87.4% and 97.7% for the SSEP and MEP, respectively. SSEP alerts were reported in five patients and MEP alerts in four patients, and new neurological deficits were observed in three patients postoperatively. The sensitivity and specificity were 100% and 97.3% for SSEP, and 100% and 98.8% for MEP, respectively. A significant difference in MEP amplitude between the concave and convex sides was observed, while significantly higher SSEP latency was observed on the concave side in patients with preoperative neurological deficits. There were 52 (59.8%) patients with abnormal IONM data. Preoperative neurological deficits (χ2  = 7.715, p = 0.005) and more than one intraspinal abnormality (χ2  = 9.186, p = 0.004) indicated a higher risk of abnormal IONM data. CONCLUSIONS: IONM can be effectively used in patients with intraspinal abnormalities who undergo posterior spinal fusion. Patients with preoperative neurological deficits and more than one intraspinal abnormality have a higher risk of abnormal IONM monitoring.

Global Alignment and Proportion (GAP) score in asymptomatic individuals: is it universal?

BACKGROUND: The global alignment and proportion (GAP) score was established based on American and European subjects, which might limit its applicability to the Chinese population due to ethnicity-related difference of sagittal alignment. PURPOSE: To analyze the applicability of GAP score in the Chinese population and to investigate the age- and gender-associated differences of spinopelvic and GAP score parameters. STUDY DESIGN: A prospective cross-sectional radiographic study. PATIENTS SAMPLE: Of 692 asymptomatic Chinese volunteers aged between 20 and 79 prospectively recruited between January 2017 and June 2019, 490 subjects were eventually included in this study. OUTCOME MEASURES: The pelvic incidence (PI), pelvic tilt (PT), sacral slope (SS), L1-S1 lordosis, L4-S1 lordosis, sagittal vertical axis (SVA), T1 pelvic angle (TPA) and global tilt (GT) were measured on lateral X-rays. The GAP scores and its parameters including relative pelvic version (RPV), relative lumbar lordosis (RLL), lordosis distribution index (LDI) and relative spinopelvic alignment (RSA) were calculated for each subject. METHODS: Subjects were divided into four groups: Group 1M: male subjects <60 years old; Group 1F: female subjects <60 years old; Group 2M: male subjects ≥60 years old and Group 2F: female subjects ≥60 years old. The GAP scores and categories were determined and compared between groups. The results of sagittal alignment were compared with the previous studies evaluating the normative sagittal alignment in other populations. Univariate linear regression analysis was carried out between pelvic incidence (PI) and sacral slope (SS), lumbar lordosis (LL) and global tilt (GT) in each group. RESULTS: The distributions of GAP categories and the updated Roussouly classification were statistically different from other populations. Significantly different distribution of GAP categories was observed between Group 1M and Group 2M, Group 1F and Group 2F, and Group 1M and Group 1F. Radiographic measurements and GAP parameters were significantly different between Group 1M and Group 2M, and Group 1F and Group 2F. Gender-related difference of parameters was more prominent between Group 1M and Group 1F. Linear relationship of PI with SS, LL and GT were different from the regression models of "ideal" sagittal alignment in GAP score. CONCLUSIONS: The GAP score might be inappropriate in Chinese population due to ethnicity-related alignment difference. Worse feasibility of GAP score was observed in female and old subjects.

How to rectify the convex coronal imbalance in patients with unstable dystrophic scoliosis secondary to type I neurofibromatosis: experience from a case series.

BACKGROUND: There was a paucity of valid information on how to rectify the convex coronal imbalance effectively in dystrophic scoliosis secondary to Type I neurofibromatosis (DS-NF1), while postoperative inadvertent aggravation of CCI occurred regularly resulting in poor patient satisfaction. We aimed to identify the risk factors for persistent postoperative CCI in DS-NF1, and to optimize the coronal rebalancing strategies based on the lessons learned from this rare case series. METHODS: NF1-related scoliosis database was reviewed and those with significant CCI (> 3 cm) were identified, sorted and the outcomes of surgical coronal rebalance were analyzed to identify the factors being responsible for failure of CCI correction. RESULTS: CCI with dystrophic thoracolumbar/lumbar apex was prone to remain uncorrected (7 failure cases in 11) when compared to those with thoracic apex (0 failure cases in 4) (63.6% vs. 0.0%, p = 0.077). Further comparison between those with and without post-op CCI showed a higher correction of main curve Cobb angle (65.9 ± 9.1% vs. 51.5 ± 37.3%, p = 0.040), more tilted instrumentation (10.3 ± 3.6° vs. 3.2 ± 3.1°, p = 0.001) and reverse tilt and translation of upper instrumented vertebra (UIV) to convex side (8.0 ± 2.3° vs. -3.4 ± 5.9°, p < 0.001; 35.4 ± 6.9 mm vs. 12.3 ± 13.1 mm, p = 0.001) in the uncorrected imbalanced group. Multiple linear regression analysis revealed that △UIV translation (pre- to post-operation) (ß = 0.832; p = 0.030) was significantly correlated with the correction of CBD. CONCLUSION: Thoracolumbar/lumbar CCI in dystrophic scoliosis was prone to suffer high risk of persistent post-op CCI. Satisfying coronal rebalance should avoid UIV tilt and translation to the convex side, tilted morphology of instrumentation and over correction maneuvers for main curve, the upper hemi-curve region in particular.

Could screw/hook insertion at the apical vertebrae with rib head dislocation effectively retract the corresponding rib head from spinal canal in dystrophic scoliosis secondary to type 1 neurofibromatosis?

BACKGROUND: Rib head dislocation (RHD) in dystrophic scoliosis of type 1 neurofibromatosis (DS-NF1) is a unique disorder caused by skeletal dystrophy and scoliotic instability. No particular surgical manipulation is mentioned in the literature to instruct the spine surgeons to effectively obtain more migration of the dislocated rib head without resection. The present study aimed to investigate the effectiveness of screw/hook insertion at vertebrae with RHDs on the retraction of penetrated rib head from spinal canal. METHODS: 37 neurologically intact patients with DS-NF1 and concomitant 53 RHDs undergoing scoliosis surgery without rib head excision were retrospectively reviewed. We used pre and postoperative whole-spine radiographs to determine the Cobb angle and the vertebral translation (VT), and the CT scans to evaluate the intraspinal rib length (IRL) and rib-vertebral angle (RVA). The dislocated ribs were assigned into two groups according to the presence of screw/hook insertion at vertebrae with RHD: screw/hook group and non-screw/hook group. RESULTS: 37 dislocated ribs with screws/hooks insertion at corresponding vertebrae were assigned into the screw/hook group and the remaining 16 dislocated ribs consisted of the non-screw/hook group. In the screw/hook group, the correction rates of Cobb angle and VT were significantly higher than the non-screw/hook group after surgery (58.7 ± 16.0% vs. 30.9 ± 12.4%, p = 0.003; 61.8 ± 18.8% vs. 35.1 ± 16.6%, p = 0.001; respectively). Similarly, more correction rates of IRL and RVA were found in the screw/hook group than the non-screw/hook group (63.1 ± 31.3% vs. 30.1 ± 20.7%, p = 0.008; 17.6 ± 9.7% vs. 7.2 ± 3.6%, p = 0.006; respectively). Multiple linear regression analysis revealed that the correction rates of Cobb angle, VT and RVA contributed significantly to correction of IRL (ß = 0.389, 0.939 and 1.869, respectively; p = 0.019, 0.001 and 0.002, respectively). CONCLUSION: Screw/hook insertion at dystrophic vertebrae with RHDs contributed significantly to the degree of retraction of penetrated rib head from spinal canal. This effectiveness is mediated by more corrections of VT and RVA.

Posterior 3-Column Osteotomy for Treatment of Congenital Kyphosis with Multiple Thoracolumbar/Lumbar Anterior Unsegmented Vertebrae: A Comparison Between Patients with Increasing Number of Anterior Unsegmented Vertebrae.

BACKGROUND: A 3-column osteotomy is sometimes challenging in congenital kyphosis (CK) with many anterior unsegmented vertebrae (AUVs). This study compared surgical outcomes of single-level 3-column osteotomy and associated complications in CK with increasing number of AUVs. METHODS: We retrospectively reviewed 25 consecutive patients with AUVs in CK who underwent surgery at a mean age of 16.2 ± 10.3 years. Patients were stratified into 2 groups according to the number of AUVs: 3 AUVs and ≥4 AUVs. Osteotomy types, surgical outcomes, and related complications were analyzed and compared between groups. RESULTS: The 3 AUVs group comprised 13 patients, and the ≥4 AUVs group comprised 12 patients. Pedicle subtraction osteotomy, grade 4 osteotomy, vertebral column resection, and vertebral column decancellation accounted for 15.4%, 38.5%, 46.1%, and 0% of procedures in the 3 AUVs group and 8.3%, 0%, 83.3%, and 8.3% of procedures in the ≥4 AUVs group. Preoperative focal kyphosis, which was significantly higher in the ≥4 AUVs group (82.9° ± 28° vs. 59.7° ± 9.4°, P = 0.010), was corrected in both groups postoperatively. The ≥4 AUVs group had significantly higher remaining kyphosis (33.6° ± 13.4° vs. 15.1° ± 9.1°, P < 0.001) with a significantly lower correction rate (61.2% ± 13.6% vs. 75.0% ± 15.6%, P = 0.001). The complication rate, mainly involving vertebral subluxation and proximal junctional kyphosis, was significantly higher in the ≥4 AUVs group than the 3 AUVs group (8/12 vs. 1/13, P = 0.004). CONCLUSIONS: Posterior single-level 3-column osteotomy can achieve satisfactory kyphosis correction in CK with 3 AUVs. Decreasing kyphosis correction and increasing surgery-related complications are prone to develop when treating CK with ≥4 AUVs.

Failed Primary Surgery in Congenital Scoliosis Caused by a Single Hemivertebra: Reasons and Revision Strategies.

OBJECTIVE: To analyze the factors causing failure of primary surgery in congenital scoliosis (CS) patients with single hemivertebra (SHV) undergoing posterior spinal fusion, and to elucidate the revision strategies. METHODS: In this retrospective study, a total of 32 CS patients secondary to SHV undergoing revision surgery from April 2010 to December 2017 due to failed primary surgery with more than 2 years follow-up were reviewed. The reasons for failure of primary surgery and revision strategies were analyzed for each patient. The radiographic parameters including coronal Cobb angle, segmental kyphosis (SK), coronal balance (CB), and sagittal vertical axis (SVA) were compared between pre- and post-revision. The complications during revision and follow-up were recorded. RESULTS: The mean age at revision surgery of the 32 CS patients was 15.8 ± 9.7 years and the average duration between primary and revision surgery was 31.0 ± 35.4 months. The reasons for failed primary surgery were severe post-operative curve progression of focal scoliosis in 14 cases (43.8%), implant failure in 17 (53.1%) and trunk imbalance in 12 (37.5%). The candidate revision strategies included thorough resection of residual hemivertebra and adjacent discs, extending fusion levels, complete pseudarthrosis resection, massive bone graft, replacement of broken rods, satellite rod fixation, horizontalization of upper/lower instrumented vertebrae and rigid fusion of structural compensatory curves were performed individually. After revision surgery, the coronal Cobb angle, SK, CB and SVA showed significant improvement (P < 0.05) with no significant correction loss during follow-up (P > 0.05). The intra-operative complications included alarming changes of neurologic monitoring in three (9.4%) patients and dual tear in two, while rod fracture re-occurred was detected in one patient at 18 months after revision. CONCLUSIONS: The common reasons for failed primary surgery in CS patients with SHV undergoing posterior spinal fusion were severe post-operative curve progression of focal scoliosis, implant failure and trunk imbalance. The revision strategies including thorough resection of residual hemivertebra and adjacent discs, extended fusion levels to structural curvature, complete pseudarthrosis resection, massive bone graft, replacement of broken internal fixation and horizontalization of upper/lower instrumented vertebrae should be individualized based on the causes of failed primary surgery.

Sequential correction technique in degenerative scoliosis with type C coronal imbalance: a comparison with traditional 2-rod technique.

OBJECTIVE: The aim of this study was to compare the radiographic and clinical outcomes in patients with degenerative scoliosis (DS) with type C coronal imbalance who underwent either a sequential correction technique or a traditional 2-rod technique with a minimum of 2 years of follow-up. METHODS: DS patients with type C coronal imbalance undergoing posterior correction surgery from February 2014 to January 2018 were divided into groups by technique: the sequential correction technique (SC group) and the traditional 2-rod technique (TT group). Radiographic parameters, including Cobb angle, coronal balance distance (CBD), global kyphosis (GK), thoracic kyphosis (TK), lumbar lordosis (LL), sagittal vertical axis (SVA), pelvic incidence (PI), pelvic tilt (PT), and sacral slope, were assessed pre- and postoperatively. The SF-36 questionnaire was used to assess quality of life. RESULTS: A total of 34 patients were included. Significant postoperative improvement in the Cobb angle of the main curve, CBD, GK, TK, LL, SVA, and PT was found in both groups (p < 0.05). Postoperatively, the coronal balance was type A in 13 patients (92.9%) in the SC group and in 16 patients (80.0%) in the TT group (p = 0.298). In the TT group, 1 patient had deteriorative coronal imbalance immediately postoperatively, and coronal imbalance deteriorated from type A to type C in 2 patients during follow-up. The scores of Physical Functioning, Role-Physical, Bodily Pain, Vitality, Social Functioning, Role-Emotional, and Mental Health were statistically improved postoperatively (p < 0.05) in both groups. Type C coronal imbalance at the last follow-up was associated with a relatively worse quality of life. There were no implant failures during follow-up in the SC group, whereas rod fracture was observed in 3 patients in the TT group. CONCLUSIONS: Compared with the traditional 2-rod technique, the sequential correction technique can simplify rod installation procedure, enhance internal instrumentation, and reduce risk of implant failures. The sequential correction technique could be routinely recommended for DS patients with type C coronal imbalance.