Does pelvic incidence tell us the risk of proximal junctional kyphosis in adult spinal deformity surgery?

PURPOSE: To investigate the relationship between pelvic incidence (PI) and proximal junctional kyphosis (PJK) in patients treated surgically for adult spinal deformity (ASD) with fusion from thoracolumbar junction to sacrum. METHODS: A consecutive series of ASD patients who underwent fusion from the thoracolumbar junction to the sacrum with a minimum of 2-year follow-up was studied. Patients were divided into low PI (≤ 50°) and high PI (> 50°) groups. We compared radiographic parameters and the rates of PJK, between the two groups. A sub-analysis was performed on patients with a postoperative PI minus lumbar lordosis mismatch between - 10° and 10° (i.e., ideally corrected). RESULTS: Sixty-three patients were included: 19 low PI and 44 high PI. Median follow-up was 34 months (range 24-103). Overall PJK rate was 38%. PJK was observed in 16% of low PI and 48% of high PI patients (p = 0.02). The odds ratio for developing PJK with a high PI compared to a low PI was 4.9 (p = 0.03). There were 32 ideally corrected patients. Eleven of these were in the low PI group, and 21 patients were in the high PI group. The incidence of PJK was 25% for ideally corrected patients. PJK occurred in none of these patients in the low PI group and 38% of patients in the high PI group (p = 0.03). CONCLUSION: When the upper-instrumented vertebra includes the thoracolumbar junction, patients with a PI > 50° are at a significantly higher risk of developing PJK compared to patients with a PI ≤ 50°.

Surgeons lack of agreement on determining preoperative radiographic and clinical shoulder balance in adolescent and adult idiopathic scoliosis patients.

PURPOSE: Preoperative shoulder balance is an important factor in determining the upper instrumented vertebrae (UIV). In adolescent and adult idiopathic scoliosis (AIS/AdIS) patients, we studied the intraobserver and interobserver reliability of spinal surgeons' assessment of preoperative shoulder balance using X-rays (XR) and anterior/posterior photographs. METHODS: An observational review of a prospective multicenter database (AIS Lenke Type 1/5/6) and prospective single-institution database (AdIS) was conducted. Ten spine surgeons reviewed AIS cases; 12 spine surgeons reviewed AdIS cases. Surgeons rated the higher shoulder: left/right/same/unsure. Reliability was calculated using Fleiss' kappa coefficient. RESULTS: Among 145 Type 1 AIS cases, intraobserver reliability was moderate-to-substantial: XR (κ = 0.59), anterior photographs (κ = 0.68), posterior photographs (k = 0.65). Interobserver reliability was fair to moderate for XR (κ = 0.31), anterior photographs (κ = 0.20), and posterior photographs (κ = 0.30). Among 52 Type 5/6 AIS cases, intraobserver reliability was substantial: XR (κ = 0.70), anterior photographs (κ = 0.76), posterior photographs (κ = 0.71). Interobserver reliability was fair to moderate for XR (κ = 0.49), anterior photographs (κ = 0.47), and posterior photographs (κ = 0.36). Among 66 AdIS cases, intraobserver reliability was substantial: XR (κ = 0.68), anterior photographs (κ = 0.67), posterior photographs (κ = 0.69). Interobserver reliability was moderate for XR (κ = 0.45), anterior photographs (κ = 0.43), posterior photographs (κ = 0.49). Within Type 1 AIS patients, attendings had better intraobserver reliabilities compared to fellows using X-rays (κ = 0.61 vs. 0.53), yet no effect of surgeon experience was seen with clinical photographs. CONCLUSION: Though surgeons' ability to agree with themselves was moderate to substantial, surgeons' ability to agree with each other was fair to moderate. Combined measures to assess preoperative shoulder balance are needed for UIV selection.

The Use of Bone Morphogenetic Protein in Spinal Transforaminal Lumbar Interbody Fusion: Our Experience.

OBJECTIVE: Since its introduction and FDA approval, rhBMP-2 has been adopted by spine surgeons as a substitute for ICBG in numerous spinal fusion techniques. As broad clinical use increased, reports on potential complications associated with rhBMP-2 also increased. We provide our experience with TLIF using rhBMP-2 or ICBG in an entirely Hispanic population. METHODS: This was a 2-year retrospective study of 67 patients, with 26 in the rhBMP-2 group and 41 in the ICBG group, who underwent TLIF. Pertinent information was obtained through review of the medical records documenting complications, intraoperative times, and EBL, among other things. RESULTS: There were 28 post-operative complications with 15 (53.6%) in the ICBG group and 13 (46.4%) in the rhBMP-2 group. The average EBL was 572.3 mL (SD: 411.8) in the ICBG group and 397.9 mL (SD: 312.2) in the rhBMP-2 group. The average intraoperative time was 243.1 minutes (SD: 79.5) in the ICBG group and 226.5 minutes (SD: 64.7) in the rhBMP-2 group. Fifty-two patients underwent open TLIF and 15 patients underwent MI TLIF. The average EBL was 571.2 mL (SD: 375.3) in the open TLIF group and 228.3 mL (SD: 299.3) in the MI-TLIF group. The average intraoperative time was 241.0 minutes (SD: 76.0) for patients in the open TLIF group and 218.8 minutes (SD: 65.0) for those in the MI-TLIF group. There were no new cancer events at any of the 2-year follow-up visits. RESULTS: Our results suggest that the safety profile of rhBMP-2 may be inferior to that of ICBG, rejecting the possibility of ICBG being replaced by rhBMP-2 as the gold standard for spinal fusion.

Moderate scoliosis continues to progress at 30-year follow-up: a call for concern?

PURPOSE: This natural history study reports long-term radiographic and clinical outcomes of patients with diagnosis of AIS with curves between 30° and 50°. Our purpose was to determine if any intervention in the natural history is warranted. METHODS: This was a longitudinal descriptive study at a single institution. We reviewed patient factors, radiographic parameters, and patient-reported outcomes at 20- and 30-year follow-up. RESULTS: A total of 31 patients were included. At skeletal maturity (which was the initial point of measurement), the median age was 17 years (range 12-21), the thoracic Cobb angle was 35° ± 5° (maximum-minimum 27°-47°), and the lumbar Cobb angle was 33° ± 7° (maximum-minimum 18°-45°). The median final follow-up was 35 years (median age 52, range 32-61) when the thoracic Cobb angle was 47° ± 12° (maximum-minimum 31°-74°) and the lumbar Cobb angle was 40° ± 17° (maximum-minimum 19°-69°). At final follow-up, 9 (29%) patients had a structural curve > 50°. Ten (32%) patients had a curve from 40° to 49° and 11 (35%) patients had a curve < 40°. The thoracic Cobb angle had progressed from < 40° to > 50° in 5 patients. Thoracolumbar and lumbar Cobb angles progressed from < 40° to greater than > 50° in 1 and 3 patients, respectively. Few patients had functional limitations according to Roland-Morris, Oswestry, and SF36 scores. Pain scores were minimal at final follow-up. CONCLUSION: All AIS curves between 30° and 50° at skeletal maturity tend to progress. Thoracic curves progress more than lumbar curves during the first 20 years and then progression slows down. The opposite happens with lumbar curves. Therefore, the rate of progression decreases with thoracic curves and increases with lumbar curves. Nevertheless, few patients have functional limitations. Further follow-up is necessary to define the true long-term outcome of moderate curves at maturity.

Adding Vertebral Bone Quality to the Fusion Risk Score: Does It Improve Predictions of Postoperative Complications?

STUDY DESIGN: Retrospective review of prospectively collected data. OBJECTIVE: The current study evaluates whether the addition of the Vertebral Bone Quality (VBQ) score to the Fusion Risk Score (FRS) improves its ability to predict perioperative outcomes. SUMMARY OF BACKGROUND DATA: The FRS was developed to assess preoperative risk in patients undergoing thoracic and lumbar fusions. It includes patient-derived and surgical variables, but it does not include one that directly accounts for bone health. The VBQ score allows assessment of bone quality and has been shown to correlate to DEXA-measured bone mineral density (BMD) scores. METHODS: The VBQ score was weighted based on a regression model and then added to the FRS (FRS/VBQ). The ability of the two scores to predict the outcomes was then assessed using the area under the curve (AUC). PATIENT SAMPLE: Patients undergoing elective thoracic and lumbar spinal fusion from January 2019 to June 2020 were included. OUTCOME MEASURES: The study evaluated various perioperative adverse outcomes, including major and minor adverse events, discharge other than home, extended length of stay, 90-day emergency department visits, 90-day readmission, and 90-day and 2-year reoperation rates. RESULTS: A total of 353 met the inclusion and exclusion criteria. The FRS/VBQ demonstrated improved predictive ability compared with the FRS alone when evaluating 90-day reoperation. Both scores showed fair predictive ability for any adverse event, major adverse events, minor adverse events, and 2-year reoperation rates, with AUCs ranging from 0.700 to 0.737. Both had poor predictive ability for the other outcomes. CONCLUSIONS: Adding VBQ to the FRS significantly enhances its predictive accuracy for reoperation rate. This updated risk score provides a more comprehensive understanding of a patient's preoperative risk profile, aiding both patients and physicians in assessing surgical risks and optimizing outcomes through preoperative risk stratification. LEVEL OF EVIDENCE: 3.

The effects of gastrojejunostomy tube placement on pulmonary and gastrointestinal complications following spinal fusion for neuromuscular scoliosis.

To evaluate whether preoperative conversion from a gastrostomy tube (G-tube) to a gastrojejunostomy tube (GJ-tube) decreases short-term postoperative aspiration pneumonia and gastrointestinal complications in children with neuromuscular scoliosis. We conducted a retrospective chart review from January 2006 to October 2021 of pediatric patients who had neuromuscular scoliosis and were fed with a G-tube before spinal fusion. Eligible patients were divided into two groups based on whether they were converted to a GJ-tube preoperatively. Preoperative characteristics and 30-day postoperative outcomes were compared between groups using Chi-square tests. Of 261 eligible patients, 205 were converted to a GJ-tube, while 56 underwent spinal fusion with a G-tube. Common complications following G-tube to GJ-tube conversion were feeding intolerance (25.2%), GJ-tube malfunction (17.7%), and at least one episode of vomiting (17.4%). Within 30 days of discharge, 12.5% of GJ-tube patients and 11.5% of G-tube patients experienced aspiration pneumonia (P = 0.85). The GJ-tube group received postoperative tube feeds 7 hours earlier than the G-tube group on average (51.6 h vs. 44.5 h, P = 0.02). Within 30 days of discharge, one (0.5%) patient from the GJ-tube group died of gastrointestinal complications unrelated to conversion and two (3.6%) patients in the G-tube group died from aspiration pneumonia (P = 0.12). Results suggest that there were no appreciable differences in outcomes between patients converted to a GJ-tube preoperatively compared to those who continued to use a G-tube. However, preoperative characteristics indicate that a higher number of complex patients were converted to a GJ-tube, indicating potential selection bias in this retrospective sample. Level of evidence: Level III.

Long-term reoperation rates following spinal fusion for neuromuscular scoliosis in nonambulatory patients with cerebral palsy.

PURPOSE: To describe the incidence of reoperation and factors contributing to surgical revision within a minimum of 10 years after spinal fusion for scoliosis in patients with nonambulatory cerebral palsy (CP). METHODS: We conducted a retrospective review of consecutive nonambulatory patients with CP who underwent primary spinal fusion at a single specialty care center with a minimum of 10 years from their index surgery (surgery dates 2001-2011). Causes of reoperation were classified as implant failure/pseudoarthrosis, surgical site infection (SSI), proximal junctional kyphosis, prominent/symptomatic implants, and implant removal. Reoperation rates with 95% confidence intervals were calculated for each time interval, and an actuarial survival curve was generated. RESULTS: 144 patients met inclusion criteria (mean age = 14.3 ± 2.6 years, 62.5% male); 85.4% had 5 years follow-up data; and 66.0% had 10 years follow-up data. Estimates from the actuarial analysis suggest that 14.9% (95% CI: 10.0-22.0) underwent reoperation by 5 years postsurgery, and 21.7% (95% CI: 15.4-30.1) underwent reoperation by 10 years postsurgery. The most common causes for reoperation were implant failure/pseudoarthrosis, SSI, and prominent/symptomatic implants. CONCLUSIONS: To our knowledge, this study is the largest long-term follow-up of nonambulatory patients with CP and neuromuscular scoliosis who underwent spinal fusion. Approximately 22% of these patients required reoperation 10 years after their index surgery, primarily due to implant failure/pseudoarthrosis, SSI, and prominent/symptomatic implants. Complications and reoperations continued throughout the 10 years period after index surgery, reinforcing the need for long-term follow-up as these patients transition into adulthood. LEVEL OF EVIDENCE: III.

Neonatal Halter Traction for Severe Cervical Spine Deformity: A Technical Case Report With 2-Year Follow-up.

BACKGROUND AND IMPORTANCE: Although rare, severe congenital cervical spine deformity can present with limited treatment options and potentially catastrophic outcomes. The use of halter traction for cervical deformity correction in children has been well described, but it has not been previously reported in the management of neonates. CLINICAL PRESENTATION: A baby girl born at full-term gestation presented with generalized hypotonia, bilateral club feet, and significant right upper extremity weakness. Imaging demonstrated a severe congenital swan-neck deformity with spinal cord compression. Halter traction was initiated in the neonatal intensive care unit with subsequent neurological and radiographic improvement. After 7 days, traction was discontinued and she was placed in a custom-fitted cervico-thoracic orthosis. At 2 years of follow-up, she remains neurologically stable with maintained cervical alignment. CONCLUSION: Halter traction followed by external bracing is technically possible in the neonatal period. For children with severe cervical congenital deformity, this technique can reduce spinal cord compression, provide significant deformity correction, and delay the need for definitive operative spinal stabilization.

Choose Wisely: Surgical Selection of Candidates for Outpatient Anterior Cervical Surgery Based on Early Complications Among Inpatients.

BACKGROUND: Anterior cervical discectomy and fusion (ACDF) and cervical disc arthroplasty (CDA) are attractive targets for transition to the outpatient setting. We assessed the prevalence of rapid responses and major complications in the inpatient setting following 1 or 2-level ACDFs and CDAs. We evaluated factors that may place patients at greater risk for a rapid response or a postoperative complication. METHODS: This was an institutional review board-approved, retrospective cohort study of adults undergoing 1 or 2-level ACDF or CDA at 1 hospital over a 2-year period (2018 and 2019). Data on patient demographic characteristics, surgical procedures, and comorbidities were collected. Rapid response events were identified by hospital floor staff and involved acute changes in a patient's clinical condition. Complications were events that were life-threatening, required an intervention, or led to delayed hospital discharge. RESULTS: In this study, 1,040 patients were included: 888 underwent ACDF and 152 underwent CDA. Thirty-six patients (3.5%) experienced a rapid response event; 22% occurred >24 hours after extubation. Patients having a rapid response event had a significantly higher risk of developing a complication (risk ratio, 10; p < 0.01) and had a significantly longer hospital stay. Twenty-four patients (2.3%) experienced acute complications; 71% occurred >6 hours after extubation. Patients with a complication were older and more likely to be current or former smokers, have chronic obstructive pulmonary disease, have asthma, and have an American Society of Anesthesiologists (ASA) score of >2. The length of the surgical procedure was significantly longer in patients who developed a complication. All patients who developed dysphagia had a surgical procedure involving C4-C5 or more cephalad. Patients with a rapid response event or complication were more commonly undergoing revision surgical procedures. CONCLUSIONS: Rapid response and complications are uncommon following 1 or 2-level ACDFs or CDAs but portend a longer hospital stay and increased morbidity. Revision surgical procedures place patients at higher risk for rapid responses and complications. Additionally, older patients, patients with chronic obstructive pulmonary disease or asthma, patients who are current or former smokers, and patients who have an ASA score of ≥3 are at increased risk for postoperative complications. LEVEL OF EVIDENCE: Prognostic Level III . See Instructions for Authors for a complete description of levels of evidence.

The role of ketamine in opioid-free spinal deformity surgery: is it possible and beneficial?

BACKGROUND: As the opioid epidemic in the United States has continued to gain momentum in recent years, the current study aims to explore the efficacy of ketamine in a traditionally challenging setting regarding pain control, and contribute toward developing an opioid-free intraoperative pain protocol in spinal deformity surgery. METHODS: Fifty-four patients who underwent spinal deformity surgery between January 1, 2017 and December 31, 2017 by one senior surgeon were included. Demographic data and preoperative opioid use was collected. Surgical details including number of levels fused, estimated blood loss, and operative time was also collected. All patients received a hydromorphone patient-controlled anesthesia (PCA) device postoperatively. 36/54 patients received perioperative ketamine during their procedure, both intraoperatively and postoperatively. The consumption of postoperative hydromorphone and the ratio of doses given by doses attempted postoperatively were recorded. Patient charts were also reviewed for documented ileus during their inpatient stay. RESULTS: Mean age was 49 years, and 31% were male. Average BMI was 24.3 kg/m2. The average number of levels fused was 11.6. Mean operative time was 10.7 hrs, and average EBL was 1,522 mL. The mean length of stay was 8 days. Average postoperative PCA use of hydromorphone in the no ketamine group (NK) (n=18) was 5.99 mg compared to 6.91 mg for those who received perioperative ketamine (K) (n=36); there was no significant difference between populations (P=0.57), although the variances was significant (P=0.044). There was no correlation between intraoperative ketamine and postoperative PCA use (r=-0.05; P=0.72). Additionally, there was no correlation between postoperative PCA use and dose of postoperative ketamine received (r=-0.15; P=0.27). The ratio of doses given: attempted was 0.61 in the NK group and 0.59 in those in the K group (P=0.79). Average postoperative hydromorphone use was 5.48 mg in patients that did not use opioids preoperatively (n=39) compared to 12.77 mg in those who used opioids preoperatively (n=9; P=0.0003). 9/54 patients had a documented ileus during their admission, while 4/9 (11%) had received ketamine (P=0.095). CONCLUSIONS: Though our study showed no significant change in postoperative opioid requirement in our population, our results show that integration of ketamine in these extensive operations fare similarly to traditional opioid-based regimens. There was also no significant association seen between ketamine use and adverse side effects such as ileus. At our institution we are currently establishing opioid-free intraoperative pain protocols that use ketamine as an adjunct, and further study will explore the effect this may have on postoperative opioid consumption for spinal surgery patients as well as postoperative patients in general.

Selecting the "Touched Vertebra" as the Lowest Instrumented Vertebra in Patients with Lenke Type-1 and 2 Curves: Radiographic Results After a Minimum 5-Year Follow-up.

BACKGROUND: The selection of the lowest instrumented vertebra (LIV) in patients with adolescent idiopathic scoliosis (AIS) is still controversial. Although multiple radiographic methods have been proposed, there is no universally accepted guideline for appropriate selection of the LIV. We developed a simple and reproducible method for selection of the LIV in patients with Lenke type-1 (main thoracic) and 2 (double thoracic) curves and investigated its effectiveness in producing optimal positioning of the LIV at 5 years of follow-up. METHODS: The radiographs for 299 patients with Lenke type-1 or 2 AIS curves that were included in a multicenter database were evaluated after a minimum duration of follow-up of 5 years. The "touched vertebra" (TV) was selected on preoperative radiographs by 2 independent examiners. The LIV on postoperative radiographs was compared with the preoperative TV. The final LIV position in relation to the center sacral vertical line (CSVL) was assessed. The CSVL-LIV distance and coronal balance in patients who had fusion to the TV were compared with those in patients who had fusion cephalad and caudad to the TV. The sagittal plane was also reviewed. RESULTS: In 86.6% of patients, the LIV was selected at or immediately adjacent to the TV. Among patients with an "A" lumbar modifier, those who had fusion cephalad to the TV had a significantly greater CSVL-LIV distance than those who had fusion to the TV (p = 0.006) or caudad to the TV (p = 0.002). In the groups with "B" (p = 0.424) and "C" (p = 0.326) lumbar modifiers, there were no differences among the TV groups. CONCLUSIONS: We recommend the TV rule as a third modifier in the Lenke AIS classification system. Selecting the TV as the LIV in patients with Lenke type-1 and 2 curves provides acceptable positioning of the LIV at long-term follow-up. The position of the LIV was not different when fusion was performed caudad to the TV but came at the expense of fewer motion segments. Patients with lumbar modifier "A" who had fusion cephalad to the TV had greater translation of the LIV, putting these patients at risk for poor long-term outcomes. LEVEL OF EVIDENCE: Therapeutic Level III. See Instructions for Authors for a complete description of levels of evidence.

A Radiographic Analysis of Lumbar Fusion Status and Instrumentation Failure After Complex Adult Spinal Deformity Surgery With Spinopelvic Fixation: Two-Year Follow-up From the Scoli-Risk-1 Prospective Database.

STUDY DESIGN: A retrospective review of prospectively collected data. OBJECTIVE: The objective of this study was to investigate the fusion status of the lumbar spine and lumbosacral junction at 2 years postoperatively after complex adult spinal deformity (ASD) surgery. SUMMARY OF BACKGROUND DATA: Achieving fusion is crucial for maintaining optimal alignment in ASD surgery. However, prospective data assessing fusion status using large patient populations are lacking in this patient population. MATERIALS AND METHODS: Postoperative radiographs of 162 patients from the Scoli-Risk-1 database, who underwent complex ASD surgery with fusion to the sacrum, were evaluated by 3 independent spine surgeons at 6-week, 6-month, and 2-year follow-up. The fusion rate of the lumbar spine segments at a 2-year follow-up was determined by using previously published radiographic grading criteria. We also assessed the prevalence of instrumentation failures. RESULTS: The interrater reliabilities for grading the fusion status were overall fair at each level evaluated (Fleiss κ, 0.337-0.439). Overall, 70.3% (114/162) demonstrated the solid fusion of the entire lumbar spine at a 2-year follow-up. The fusion rates of each segment were L1/L2: 87.0%, L2/L3: 82.0%, L3/L4: 83.9%, L4/L5: 89.5%, and L5/S1: 89.5%. Pedicle screw loosening was the most frequent implant failure throughout the observation period (9.2%, 11.6%, and 11.0% at 6-wk, 6-mo, and 2-y follow-up, respectively). No rod breakage was observed at 6 weeks, increasing to 9.8% at 2-year follow-up. The prevalence of postoperative proximal junctional kyphosis was 5.5% at 6 weeks, showing no difference at 2 years postoperative. CONCLUSIONS: In this series of complex ASD surgeries often requiring 3-column osteotomies, 70.3% showed solid fusion of the entire lumbar spine, including the lumbosacral junction. The lumbosacral segments showed a relatively high fusion rate at a 2-year follow-up likely due to the frequent use of anterior column support and graft. The prevalence of rod breakage increased as follow-up proceeded to 9.8%, which was most commonly observed at the lumbosacral junction. LEVEL OF EVIDENCE: Level IV.

Modern Surgical Management of Early Onset and Adolescent Idiopathic Scoliosis.

The early principles of spinal fusion in the adolescent population focused on preventing progression while simultaneously correcting the spinal deformity. These principles have remained relatively unchanged since their introduction more than a century ago, but recent improvements in imaging, instrumentation, and corrective techniques have provided new insight on the diagnosis, management, and postoperative care of this condition. Treatment options for the management of patients with early onset scoliosis have also evolved dramatically over the last 2 decades. Further knowledge on the physiology of lung development and the detrimental effects of early fusion in the early onset scoliosis population has led to the development of growth friendly implants and other surgical techniques that allow correction of the deformity while maintaining spine, lung, and chest wall development. The following is an overview of current techniques on the management of adolescent idiopathic and early onset scoliosis to help provide guidance on the available surgical alternatives to address these conditions.

The "kickstand rod" technique for correction of coronal imbalance in patients with adult spinal deformity: initial case series.

OBJECTIVE: The objective of this study was to describe and evaluate a new surgical procedure for the correction of coronal imbalance (CI) in adult spinal deformity patients, called the "kickstand rod" technique. METHODS: The authors analyzed the records of 24 consecutive patients with pediatric and adult spinal deformity and CI treated between July 2015 and October 2017 with a long-segment fusion and a kickstand rod. For the kickstand rod technique, an iliac screw was placed on the ipsilateral side of the trunk shift and connected proximally through a side-by-side domino link to the thoracolumbar junction; this rod was distracted to promote coronal plane balancing. Distraction occurred with the rod on the contralateral side locked in order to preserve sagittal correction. Radiographic and clinical analyses were conducted to evaluate the outcomes and possible complications of the kickstand rod technique. RESULTS: The mean age of the patients was 55 years (range 14-73 years). Eighteen of the 24 patients were female. CI preoperatively was a mean of 63 mm, and the mean measurement at the final follow-up (mean duration 1.4 years) was 47 mm. There were no neurological, vascular, or implant-related complications in any of the patients. One patient developed wound dehiscence that was successfully treated without implant removal, and one developed proximal junctional kyphosis requiring extension of the construct proximally. One patient also returned to the operating room for excision of a spinous process. There were no complaints about screw prominence, kickstand construct failure, or significant worsening of CI after surgery. CONCLUSIONS: The kickstand rod technique is safe and effective for the correction of CI in spinal deformity patients. This technique was found to provide marked coronal correction and additional strength to the overall construct without significant adverse consequences.

The Amount of Relative Curve Correction Is More Important Than Upper Instrumented Vertebra Selection for Ensuring Postoperative Shoulder Balance in Lenke Type 1 and Type 2 Adolescent Idiopathic Scoliosis.

STUDY DESIGN: Retrospective review of a prospectively collected multicenter database. OBJECTIVE: To assess how "overcorrection" of the main thoracic curve without control of the proximal curve increases the risk for shoulder imbalance in Lenke type 1 Adolescent Idiopathic Scoliosis (AIS). SUMMARY OF BACKGROUND DATA: Postop shoulder imbalance is a common complication following AIS surgery. It is thought that a more cephalad upper-instrumented vertebra (UIV) decreases the risk of shoulder imbalance in Lenke type 1 and 2 curves; however, this has not been proven. METHODS: Thirteen surgeons reviewed preop and 5-year postop clinical photos and PA radiographs of patients from a large multicenter database with Lenke type 1 and 2 AIS curves who were corrected with pedicle screw/rod constructs. Predictors of postop shoulder imbalance were identified by univariate analysis; multivariate analysis was done using the classification and regression tree method to identify independent drivers of shoulder imbalance. RESULTS: One hundred forty-five patients were reviewed. The UIV was T3-T5 in 87% of patients, with 8.9% instrumented up to T1 or T2. Fifty-two (36%) had shoulder imbalance at 5 years. On classification and regression tree analysis when the proximal thoracic (PT) Cobb angle was corrected more than 52%, 80% of the patients had balanced shoulders. Similarly, when the PT curve was corrected less than 52% and the main thoracic (MT) curve was corrected less than 54%, 87% were balanced. However, when the PT curve was corrected less than 52%, and the MT curve was corrected more than 54%, only 41% of patients had balanced shoulders (P = 0.05). This relationship was maintained regardless of the UIV level. CONCLUSION: In Lenke type 1 and 2 AIS curves, significant correction of the main thoracic curve (>54%) with simultaneous "under-correction" (<52%) of the upper thoracic curve resulted in shoulder height imbalance in 59% of patients, regardless of the UIV. This suggests the PT curve must be carefully scrutinized in order to optimize shoulder balance, especially when larger correction of the MT curve is performed. LEVEL OF EVIDENCE: 2.

Evaluation of a more ventral starting point for thoracic pedicle screws: higher maximal insertional arc and more medial and safer screw angulation.

OBJECTIVETo demonstrate that a more ventral starting point for thoracic pedicle screw insertion, produced by aggressively removing the dorsal transverse process bone down to the superior articular facet (SAF), results in a larger margin for error and more medial screw angulation compared to the traditional dorsal starting point (DSP). The margin for error will be quantified by the maximal insertional arc (MIA).METHODSThe study population included 10 consecutive operative patients with adult idiopathic scoliosis who underwent primary surgery. All measurements were performed using 3D visualization software by an attending spine surgeon. The screw starting points were 2 mm lateral to the midline of the SAF in the mediolateral direction and in the center of the pedicle in the cephalocaudal direction. The DSP was on the dorsal cortex. The ventral starting point (VSP) was at the depth of the SAF. Measurements included distance to the pedicle isthmus, MIA, and screw trajectories.RESULTSTen patients and 110 vertebral levels (T1-11) were measured. The patients' average age was 41.4 years (range 18-64 years). The pedicle isthmus was largest at T1 (4.04 ± 1.09 mm), and smallest at T5 (1.05 ± 0.93 mm). The distance to the pedicle isthmus was 7.47 mm for the VSP and 11.92 mm for the DSP (p < 0.001). The MIA was 15.3° for the VSP and 10.1° for the DSP (p < 0.001). Screw angulation was 21.7° for the VSP and 16.8° for the DSP (p < 0.001).CONCLUSIONSA more ventral starting point for thoracic pedicle screws results in increased MIA and more medial screw angulation. The increased MIA represents an increased tolerance for error that should improve the safety of pedicle screw placement. More medial screw angulation allows improved triangulation of pedicle screws.