The Transverse Process Trajectory Technique: An Alternative for Thoracic Pedicle Screw Implantation-Radiographic and Biomechanical Analysis.

BACKGROUND: This study evaluates the accuracy, biomechanical profile, and learning curve of the transverse process trajectory technique (TPT) compared to the straightforward (SF) and in-out-in (IOI) techniques. SF and IOI have been used for fixation in the thoracic spine. Although widely used, there are associated learning curves and symptomatic pedicular breaches. We have found the transverse process to be a reproducible pathway into the pedicle. METHODS: Three surgeons with varying experience (experienced [E] with 20 years in practice, surgeon [S] with less than 10 years in practice, and senior resident trainee [T] with no experience with TPT) operated on 8 cadavers. In phase 1, each surgeon instrumented 2 cadavers, alternating between TPT and SF from T1 to T12 (n = 48 total levels). In phase 2, the E and T surgeons instrumented 1 cadaver each, alternating between TPT and IOI. Computed tomography scans were analyzed for accuracy of screw placement, defined as the percentage of placements without critical breaches. Axial pullout and derotational force testing were performed. Statistical analyses include paired t test and analysis of variance with Tukey correction. RESULTS: Overall accuracy of screw placement was comparable between techniques (TPT: 92.7%; SF: 97.2%; IOI: 95.8%; P = .4151). Accuracy by technique did not differ for each individual surgeon (E: P = .7733; S: P = .3475; T: P = .4191) or by experience level by technique (TPT: P = .1127; FH: P = .5979; IOI: P = .5935). Pullout strength was comparable between TPT and SF (571 vs 442 N, P = .3164) but was greater for TPT versus IOI (454 vs 215 N, P = .0156). There was a trend toward improved derotational force for TPT versus SF (1.06 vs 0.93 Nm/degrees, P = .0728) but not for TPT versus IOI (1.36 vs 1.16 Nm/degrees, P = .74). Screw placement time was shortest for E and longest for T for TPT and SF and not different for IOI (TPT: P = .0349; SF: P < .0001; IOI: P = .1787) but did not vary by technique. CONCLUSIONS: We describe the TPT, which uses the transverse process as a corridor through the pedicle. TPT is an accurate method of thoracic pedicle screw placement with potential biomechanical advantages and with acceptable learning curve characteristics. CLINICAL RELEVANCE: This study provides the surgeon with a new trajectory for pedicle screw placement that can be used in clinical practice.

Feasibility of Single-Staged Bilateral Anterior Scoliosis Correction in Growing Patients.

STUDY DESIGN: Retrospective analysis. OBJECTIVES: The objective of this study was to analyze the feasibility of correcting double-curve scoliosis using dynamic scoliosis correction (DSC, also known as vertebral body tethering), which requires a bilateral anterior approach with deflation of both lungs. Typically, this approach falls under the exclusionary criteria for the eligibility for anterior scoliosis surgery. No data exists on the feasibility of single-staged bilateral DSC. METHODS: A retrospective analysis was performed utilizing the data from 25 patients who underwent a bilateral anterior thoracic approach and instrumentation. Thirty-day postoperative complication rates were analyzed. A learning curve subanalysis was also performed to compare the first 12 patients to the remainder of the 13 patients, with a T-test (P ≤ .05). RESULTS: Of the 25 patients treated, there was 1 intraoperative event: After performing lumbar DSC, the contralateral DSC was abandoned due to unexpected pleural scarring and staged selective thoracic fusion was performed. We observed 4 postoperative complications: 2 patients had recurrent pleural effusions, 1 patient was diagnosed with pneumonia, and 1 patient had a minor pulmonary embolism without cardiopulmonary consequences (after an international 24 hour flight). All patients recovered well. We observed a significant influence of learning curve on surgical time (328 vs 280 min, P = .03) and blood loss (480 vs 197 mL, P = .03). CONCLUSION: Data suggests that bilateral, single-stage surgery for DSC is feasible albeit with an elevated complication rate that may partially attributable to the learning curve. Future research should focus on the cause of pulmonary complications and include a matched comparative analysis with traditional posterior fusion.

Bracing in Adolescent Idiopathic Scoliosis Trial (BrAIST): Development and Validation of a Prognostic Model in Untreated Adolescent Idiopathic Scoliosis Using the Simplified Skeletal Maturity System.

STUDY DESIGN: Prognostic study and validation using prospective clinical trial data. OBJECTIVE: To derive and validate a model predicting curve progression to ≥45° before skeletal maturity in untreated patients with adolescent idiopathic scoliosis (AIS). SUMMARY OF BACKGROUND DATA: Studies have linked the natural history of AIS with characteristics such as sex, skeletal maturity, curve magnitude, and pattern. The Simplified Skeletal Maturity Scoring System may be of particular prognostic utility for the study of curve progression. The reliability of the system has been addressed; however, its value as a prognostic marker for the outcomes of AIS has not. The BrAIST trial followed a sample of untreated AIS patients from enrollment to skeletal maturity, providing a rare source of prospective data for prognostic modeling. METHODS: The development sample included 115 untreated BrAIST participants. Logistic regression was used to predict curve progression to ≥45° (or surgery) before skeletal maturity. Predictors included the Cobb angle, age, sex, curve type, triradiate cartilage, and skeletal maturity stage (SMS). Internal and external validity was evaluated using jackknifed samples of the BrAIST data set and an independent cohort (n = 152). Indices of discrimination and calibration were estimated. A risk classification was created and the accuracy evaluated via the positive (PPV) and negative predictive values (NPV). RESULTS: The final model included the SMS, Cobb angle, and curve type. The model demonstrated strong discrimination (c-statistics 0.89-0.91) and calibration in all data sets. The classification system resulted in PPVs of 0.71-0.72 and NPVs of 0.85-0.93. CONCLUSIONS: This study provides the first rigorously validated model predicting a short-term outcome of untreated AIS. The resultant estimates can serve two important functions: 1) setting benchmarks for comparative effectiveness studies and 2) most importantly, providing clinicians and families with individual risk estimates to guide treatment decisions. LEVEL OF EVIDENCE: Level 1, prognostic.

Outcome Measures in Adult Spine Surgery: How Do We Identify the Outcomes of Greatest Utility for Research?

The goal of any surgical intervention in spine surgery is to restore function, relieve pain, and improve quality of life. Traditional assessments of patient outcomes failed to accurately reflect patient's quality of life improvement. Patient-reported outcome measures (PROM) were designed to translate the patients perceived health into quantitative data. The data can help providers gauge the severity of a condition, develop a treatment plan, and follow the patient over time to determine treatment efficacy. Both in clinical practice and research, PROMs are helpful in comparing treatment options and advancing the field of spine surgery. This article discusses the utility and reliability of patient-reported outcomes, utilization in research, and provides examples of the most widely utilized PROMs in spine surgery.

The Assessment of Clinically Significant Differences in Treating Spinal Deformity Using the SRS Questionnaire: What Is the Threshold of Change That Is Meaningful to Patients?

BACKGROUND: The measurement of health-related quality of life is important in spinal deformity surgery. The Scoliosis Research Society questionnaire has allowed disease-specific research in this area, and determining the minimal clinically important difference (MCID) is as important as it is elusive. We seek to further refine our estimations of clinically perceived improvements by the patient. METHODS: We used an anchor-based approach for each domain of the SRS questionnaire to compare changes at 1 year after treatment. We set the MCID as the upper 95% boundary of the "no change" group bordering the "improvement" arm, where the patients may start to perceive their own change toward the better. We compared this with the mean change. RESULTS: The threshold value for the MCID was 0.54 for the pain domain, 0.31 for function, 0.62 for self-image, and 0.5 for mental health. The mean changes in our group's pain and self-image exceeded their MCID. CONCLUSIONS: Compared with our previous work, we further attempted to refine our assessment of the MCID in spinal deformity. Pain continues to show clinically significant improvement, and self-image also demonstrated mean improvement over its estimated MCID. LEVEL OF EVIDENCE: 2. CLINICAL RELEVANCE: This result in self-image is an important addition to the MCID literature, given its lack of consistency in previous work.

The Use of Tranexamic Acid to Reduce Surgical Blood Loss: A Review Basic Science, Subspecialty Studies, and The Evolution of Use in Spine Deformity Surgery.

Significant blood loss is often seen in orthopedic surgeries, especially complex spinal procedures that constitute long surgical times, large incisions, and rich blood supplies. Tranexamic acid (TXA), a synthetic analog of the amino acid lysine, has proven to be a cost-effective method in decreasing transfusion rates and avoiding complications associated with low blood volume. Recent data on TXA's use in spine surgery suggest that TXA remains both efficacious and safe, although the ideal dosing and timing of administration is still a point of disagreement. The purpose of this study is to review the literature for the use of TXA in spine surgery to better understand its safety profile and ideal dosage. This narrative review on TXA was conducted on prospective orthopedic studies that used TXA in spine deformity surgery. TXA in adult and pediatric spine surgery has decreased intraoperative and postoperative blood loss, decreasing the need for blood transfusions. The most common dose in the literature is a 10 mg/kg loading dose, followed by 1 mg/kg per hour. Although the proper dosing of TXA for spine surgery remains debatable, studies have proven that TXA is effective at reducing blood loss without increasing the risk of thrombotic events.

Factors Predictive of Orthopaedic In-training Examination Performance and Research Productivity Among Orthopaedic Residents.

INTRODUCTION: Selection of qualified candidates for orthopaedic residency is necessary for growth and innovation. The purpose of this study was to determine predictors of Orthopaedic In-training Exam (OITE) performance and research productivity. METHODS: A survey was distributed to 13 residency programs collecting demographics, United States Medical Licensing Examination (USMLE) and OITE scores, and authored publications. Associations between preresidency qualifications and OITE scores and publications were determined. RESULTS: A total of 274 of 294 surveys were returned (93.2%). We found a positive correlation between USMLE step 1 and 2 scores with recent OITE percentile (P < 0.001). Preresidency authorship (P < 0.001) and postgraduate training year (P < 0.001) were independent predictors of authorship during residency, whereas USMLE step 1 score was not (P = 0.094). CONCLUSION: Candidates who perform well on the USMLE are likely to perform well on the OITE, whereas those with greater authored publications are likely to continue research during residency.

Guidelines on How to Perform a Meta-Analysis in Spine Surgery: Strengths and Weaknesses of Design.

There are many questions in the literature that remain unanswered due to the paucity of available subjects or the large sample size needed to detect a difference. A meta-analysis consists of integrating together data from multiple studies into one larger data set in order to increase the subject size and power of a paper. In essence, it is a systematic review in which one uses statistical methods to summarize the results of these studies. It is important that a meta-analysis be performed in a systematic and orderly manner with the assistance of a statistician. When carried out correctly, these studies serve as powerful tools to help us better address our knowledge. Because of their complexity, they are prone to bias at multiple levels. This article will discuss the steps involved in performing a meta-analysis, select good studies, as well as explain the statistics conducted in these studies. Furthermore, we will discuss examples from the literature that demonstrate a good meta-analysis.

Understanding Classification Systems in Spine Deformity.

Classification systems provide organization for pathologic conditions and guide treatment for similar disease states. Spine deformity is a growing field with newer classification systems being developed as our surgical techniques and clinical understanding advances. The evolution of these classification systems reflects our current knowledge and are used to better understand the evolving field of spine surgery. Currently, classification systems in spine surgery range from describing deformity in different age groups and different regions of the spine to describing various osteotomies and the severity of proximal junctional kyphosis. This paper will describe what makes a successful classification system in spine deformity. Old classification systems will be briefly described and their limitations that necessitated the need for newer classification systems. Newer systems will also be reviewed and the importance of specific radiographic parameters. Finishing this review, clinicians will be able to pick which systems are ideal for their practice.

Comparison of Stand-Alone, Transpsoas Lateral Interbody Fusion at L3-4 and Cranial vs Transforaminal Interbody Fusion at L3-4 and L4-5 for the Treatment of Lumbar Adjacent Segment Disease.

STUDY DESIGN: Retrospective cohort study. OBJECTIVE: To compare outcomes and complications of stand-alone minimally invasive lateral interbody fusion (LIF) vs revision posterior surgery for the treatment of lumbar adjacent segment disease. METHODS: Adults who underwent LIF or transforaminal lumbar interbody fusion (TLIF) for adjacent segment disease were compared. Exclusion criteria: >grade 1 spondylolisthesis, posterior approach after LIF, and L5/S1 surgery. Patient demographics, estimated blood loss, hospital length of stay, complications, reoperations, health-related quality of life measures, and radiographs were examined. Data were analyzed with the χ2, Wilcoxon signed rank, and Mann-Whitney U tests. RESULTS: A total of 17 LIF and 16 TLIF patients were included. Demographics were similar. Follow up was similar (LIF: 22.9 ± 11.8 months vs TLIF: 22.0 ± 4.6 months; P = .86). The LIF patients had significantly less blood loss (LIF: 36 ± 16 mL vs TLIF: 700 ± 767 mL; P < .001) and shorter length of stay (LIF: 2.6 ± 2.9 days vs TLIF: 3.3 ± 0.9 days; P = .001). There were no intraoperative complications. Revision rate was 4 of 17 in LIF and 3 of 16 in TLIF (P = .73). Baseline health-related quality of life and radiographic measurements were similar. In both groups, back and leg pain scores significantly improved, and in LIF, the Owestry Disability Index, and EuroQol-5D significantly improved. The LIF had a significant increase in intervertebral height (LIF: 4.8 ± 2.9 mm, P < .001, TLIF: 1.3 ± 3.4 mm, P = .37), which was significantly greater for LIF than TLIF (P = .002). Similarly, LIF had a significant increase in segmental lordosis (LIF: 5.6° ± 4.9°, P < .001, TLIF: 3.6° ± 8.6°, P = .16), which was not significantly different between groups. CONCLUSIONS: Patients with adjacent segment disease may receive significant benefit from stand-alone LIF or TLIF. The LIF offers advantages of less blood loss and a shorter hospital stay. LEVEL OF EVIDENCE: 3.

Congenital anterior shoulder dislocation in a newborn treated with closed reduction.

Case: This rare case presents an isolated congenital shoulder dislocation in a twin delivery, without traumatic delivery. Delivered by emergent cesarean section at 33 weeks gestation, the infant presented with a lateral shoulder crease with x-rays showing anterior and inferior dislocation. Treatment included prompt reduction and stabilization, with follow-up ultrasound demonstrating a physeal injury. Conclusions: This case report presents the only published congenital shoulder dislocation in an infant after an atraumatic twin cesarean delivery. Prompt reduction, stabilization, and ultrasound imaging to assess for physeal injury is our recommended management for this scenario.

Approaching Spine Research in an Outreach Setting: What Type of Infrastructure is Conducive for Conducting Research?

Organizing medical research in an outreach setting can be a challenging task, especially when it involves complex spine procedures in patients whom it is difficult to follow-up for long term. Disease severity at presentation is often advanced in outreach settings due to limited local resources, surgeon expertise, and hospital infrastructure. Case complexity can present a challenge to local and outreach surgeons alike. This article will describe what encompasses an ideal outreach program as it relates to spine, how to manage cost in an outreach setting, collection of outcome data, and maintaining long-term follow-up. As one of the criticisms of medical outreach is the relative paucity of outcome data, this article discusses methods to collect and report outcomes abroad. We also discuss the value of translating outcome questionnaires to different languages and cross-cultural comparisons. In addition, relatively rare pathologies are often seen with greater frequency abroad. These patients are ideally suited for a focused case series than can guide treatment decisions.

Comprehensive Assessment of Outcomes From Patients With Severe Early-onset Scoliosis Treated With a Vertebral Column Resection: Results From an SRS Global Outreach Site (FOCOS) in Ghana.

BACKGROUND: Early-onset scoliosis (EOS) remains a challenging pediatric spine condition to manage. Some severe deformities can be managed with a vertebral column resection (VCR), which is fraught with high complication rates and the outcomes have not been well reported. The purpose of this study is to provide an assessment of operative, radiographic, and clinical outcomes from children diagnosed with severe EOS treated with a VCR. METHODS: We performed a retrospective review of prospectively collected data. Basic demographic data was collected along with the diagnosis, procedure performed, FOCOS risk score, blood loss (estimated blood loss), operative time, neuromonitoring events, intraoperative complications, and clinical follow-up. Coronal and sagittal radiographic parameters were measured by the first author. RESULTS: We identified 14 patients with posttuberculosis deformity (n=7) or congenital deformity (n=7) that underwent VCR between 2013 and 2016 (5 female; age, 7.7±3 y; body mass index, 17.7±2.8). There was significant improvement in coronal radiographic parameters (primary curve: 55 to 21 degrees, secondary: 37 to 13 degrees, T1-12 length: 137 to 151 mm, T1-S1 length: 219 to 271 mm, P<0.05) and sagittal parameters (kyphosis: 85 to 41 degrees, compensatory lordosis 56 to 39 degrees, P<0.001). There was no change in chest width, sagittal vertical axis, or pelvic tilt. Mean proximal junctional kyphosis (PJK) angle was 12±9 degrees and distal junctional kyphosis angle was 9±17 degrees. Estimated blood loss was 860±520 mL and operative time was 200±66 minutes. Seven cases had neuromonitoring changes that improved with corrective maneuvers and blood pressure elevation. Three patients required reoperation for junctional breakdown with 1 having a third operation for an infection, while 2 additional patients had evidence of radiographic PJK. CONCLUSIONS: VCR in the setting of EOS has excellent radiographic outcomes but a high complication profile. Half of these cases had neuromonitoring changes intraoperatively that improved without lasting neurological deficit. Three patients had PJK and 1 had an infection requiring reoperation. LEVEL OF EVIDENCE: Level IV-case series.

Preliminary Analysis of Factors Associated with Blood Loss in Neuromuscular Scoliosis Surgery.

STUDY DESIGN: A retrospective review was conducted of 57 consecutive patients (26 female; mean age: 16.6 years) who underwent posterior or combined anterior-posterior spinal fusion for neuromuscular scoliosis (NMS) from 2006 and 2007. OBJECTIVES: We aimed to assess which patient and surgical factors are predictive of increased blood loss and transfusion requirements during spinal fusion for NMS. BACKGROUND: Spinal fusion surgery in patients with NMS has been associated with significant intraoperative blood loss and transfusion requirements. Specific factors predictive of greater blood loss have not been delineated; recognizing these factors will assist predicting the need for blood products and antifibrinolytics. METHODS: Data gathered included demographic, operative (operative time, levels fused, estimated blood loss, cell saver transfused, IV fluids transfused, and units transfused), and laboratory parameters (hemoglobin, hematocrit, platelet count, prothrombin time, partial prothrombin time, and international normalized ratio). Multivariate linear regression was used to identify parameters associated with greater intraoperative blood loss and transfusion requirements. RESULTS: Eighty-three percent of patients underwent primary surgery with mean levels fused of 13.5. Regression analysis showed a statistically significant increase in blood loss with age (p = 0.00), operative time (p = 0.00), and postoperative platelets (p = 0.016). Each year of increasing age corresponded with an increase of 50 cc of estimated blood loss (EBL). Each additional hour of operative time was associated with an additional EBL of 147.7 cc. Each additional unit of postoperative platelets was associated with an EBL decrease of 2.8 cc. Units transfused increased with age (p = 0.00): each year of increasing age corresponded with an increase of 0.04 units of blood transfused. CONCLUSIONS: Patients with NMS remain a challenging group of patients to treat. We find that age, operative time, and postoperative platelets are predictive of increased blood loss while only age was related to greater transfused units. Our findings may predict the need for blood products and antifibrinolytic agents preoperatively in this heterogeneous population, especially as patients age.

Global Spinal Alignment in Cervical Kyphotic Deformity: The Importance of Head Position and Thoracolumbar Alignment in the Compensatory Mechanism.

BACKGROUND: Previous studies have evaluated cervical kyphosis (C-kypho) using cervical curvature or chin-brow vertical angle, but the relationship between C-kypho and global spinal alignment is currently unknown. OBJECTIVE: To elucidate global spinal alignment and compensatory mechanisms in primary symptomatic C-kypho using full-spine radiography. METHODS: In this retrospective multicenter study, symptomatic primary C-kypho patients (Cerv group; n = 103) and adult thoracolumbar deformity patients (TL group; n = 119) were compared. We subanalyzed Cerv subgroups according to sagittal vertical axis (SVA) values of C7 (SVAC7 positive or negative [C7P or C7N]). Various Cobb angles (°) and SVAs (mm) were evaluated. RESULTS: SVAC7 values were -20.2 and 63.6 mm in the Cerv group and TL group, respectively (P < .0001). Various statistically significant compensatory curvatures were observed in the Cerv group, namely larger lumbar lordosis (LL) and thoracic kyphosis. The C7N group had significantly lower SVACOG (center of gravity of the head) and SVAC7 (32.9 and -49.5 mm) values than the C7P group (115.9 and 45.1 mm). Sagittal curvatures were also different in T4-12, T10-L2, LL4-S, and LL. The value of pelvic incidence (PI)-LL was different (C7N vs C7P; -2.2° vs 9.9°; P < .0003). Compensatory sagittal curvatures were associated with potential for shifting of SVAC7 posteriorly to adjust head position. PI-LL affected these compensatory mechanisms. CONCLUSION: Compensation in symptomatic primary C-kypho was via posterior shifting of SVAC7, small T1 slope, and large LL. However, even in C-kypho patients, lumbar degeneration might affect global spinal alignment. Thus, global spinal alignment with cervical kyphosis is characterized as head balanced or trunk balanced.

Proximal Junctional Kyphosis Prevention Strategies: A Video Technique Guide.

BACKGROUND: Proximal junctional kyphosis (PJK) is a well-recognized complication in patients undergoing posterior instrumented fusion procedures for adult spinal deformity. Strategies that reduce rates of PJK have the potential to improve the safety of these operations and decrease cost by eliminating the need for revision surgery. OBJECTIVE: To present a set of surgical techniques that can decrease rates of PJK in adults undergoing surgery for spinal deformity. METHODS: We summarize the use of vertebroplasty, transverse process hooks, terminal rod contouring, and ligament augmentation as means to reduce rates of PJK. RESULTS: We present PJK prevention strategies and a video technique guide that are safe, technically feasible, and add minimal operative time to these surgical procedures. When applied to appropriate high-risk patients, these techniques have the potential to dramatically reduce rates of PJK, which improves quality of life and decreases the cost associated with this treating adult spinal deformity. CONCLUSION: PJK prevention strategies represent a critical area for improvement in surgery for adult spinal deformity. We present a summary of techniques that are safe, feasible, and add minimal time to the overall procedure. These techniques warrant investigation in a thoughtful, prospective manner, but are supported by existing data and compelling biomechanical rationale. Our hope is that these strategies can be applied, particularly in high-risk patients, to help reduce rates of PJK.

Drivers of Medicare Reimbursement for Thoracolumbar Fusion: An Analysis of Data From The Centers For Medicare and Medicaid Services.

STUDY DESIGN: A retrospective observational study. OBJECTIVE: The purpose of this study is to examine the variation in thoracolumbar fusion (TLF) payment and determine the drivers of this variation. SUMMARY OF BACKGROUND DATA: As health care spending continues to increase, variation in surgical procedures reimbursements has come under more scrutiny. TLF is an example of a high-cost, proven-benefit procedure that is often the focus of Centers for Medicare and Medicaid Services (CMS) administrators. There is a wide variation in TLF charges, but the drivers for this variation are not clear. METHODS: Claims for TLF were identified in the CMS data by analyzing Diagnosis Related Group (DRG) number 460 ("Spinal Fusion Except Cervical without Major Complications or Comorbidities"). Data on factors that may impact cost of care were collected from four sources: the United States Census Bureau, CMS, the Dartmouth Atlas, and WWAMI Rural Health Research Center. These were then grouped into seven categories: quality, supply, demand, substitute treatment availability, patient characteristics, competitive factors, and provider characteristics. Predictive reimbursement models were created from the data using multivariate linear regression to understand the factors that influence TLF reimbursement. RESULTS: There was significant geographic variability in reimbursement. The largest contribution to reimbursement variation came from variables in the demand (ΔR = 13.4%, P < 0.001), supply (ΔR = 9.2%, P < 0.001), and competitive factor domains (ΔR = 9.1%, P < 0.001). The top three drivers that increased reimbursement were provider charges (ß = 0.37, P < 0.001), total Medicare reimbursement in the region (ß = 0.19, P < 0.001), and the number of spinal surgeries per 1000 patients in that region (ß = 0.06, P = 0.02). Institutional volume, a surrogate for quality was negatively associated with TLF reimbursement. CONCLUSION: There was wide variation in reimbursement for TLF across the U.S. The variables that drive TLF reimbursement variation include supply, demand, and competition. Interestingly, quality of care was not associated with increased TLF reimbursement. LEVEL OF EVIDENCE: N/A.