Dysphagia After Anterior Cervical Spine Surgery: Pathophysiology, Diagnosis, and Management

Anterior cervical spine surgery (ACSS) is a surgical intervention widely used for a myriad of indications including degenerative, oncologic, inflammatory, traumatic, and congenital spinal conditions. A primary concern for surgeons performing ACSS is the postoperative development of oropharyngeal dysphagia. Current literature reports a wide incidence of this complication ranging from 1 to 79%. Dysphagia after ACSS is multifactorial, with common risk factors being prolonged duration of operation, revision surgeries, multilevel surgeries, and use of recombinant human bone morphogenetic protein-2. Many technical strategies have been developed to reduce the risk of postoperative dysphagia, including the development of low-profile implants and retropharyngeal local steroid application. In this article, we review the most recent literature regarding the epidemiology and pathophysiology, diagnostic criteria, risk factors, and management of dysphagia after ACSS.

Preserving privacy in big data research: the role of federated learning in spine surgery

PURPOSE

Integrating machine learning models into electronic medical record systems can greatly enhance decision-making, patient outcomes, and value-based care in healthcare systems. Challenges related to data accessibility, privacy, and sharing can impede the development and deployment of effective predictive models in spine surgery. Federated learning (FL) offers a decentralized approach to machine learning that allows local model training while preserving data privacy, making it well-suited for healthcare settings. Our objective was to describe federated learning solutions for enhanced predictive modeling in spine surgery.

METHODS

The authors reviewed the literature.

RESULTS

FL has promising applications in spine surgery, including telesurgery, AI-based prediction models, and medical image segmentation. Implementing FL requires careful consideration of infrastructure, data quality, and standardization, but it holds the potential to revolutionize orthopedic surgery while ensuring patient privacy and data control.

CONCLUSIONS

Federated learning shows great promise in revolutionizing predictive modeling in spine surgery by addressing the challenges of data privacy, accessibility, and sharing. The applications of FL in telesurgery, AI-based predictive models, and medical image segmentation have demonstrated their potential to enhance patient outcomes and value-based care.

Minimally Invasive Techniques in the Surgical Management of Traumatic Pediatric Thoracolumbar Fractures

BACKGROUND

Thoracolumbar (TL) fractures are uncommon in children. While surgical treatment is recommended for unstable TL fractures, there is no consensus on appropriate surgical treatment. We present a case series of pediatric patients with traumatic TL fractures treated with minimally invasive techniques. We discuss our early experience and technical challenges with navigation and robotic-assisted fixation.

METHODS

A retrospective review of a prospectively maintained trauma database from February 2018 to February 2023 of all pediatric patients (<18 years old) undergoing percutaneous fixation for unstable TL fractures was performed. Minimally invasive techniques included fluoroscopy and/or navigation-guided or robotic-assisted surgery. Clinical course, radiographic findings, and technical challenges were reviewed.

RESULTS

A cohort of 12 patients (age range, 4-17 years) with 6 (50%) Chance fractures, 2 (16%) pars fractures, 2 (16%) pedicle fracture, 1 (8%) burst fracture, and 1 (8%) other fracture were identified. Nine patients had fractures involving the lumbar spine, and the remaining 3 had thoracic fractures. In all cases, percutaneous pedicle screws were placed above and below the fracture with the use of neuronavigation or robotic-assisted navigation (n = 2). Blood loss was <30 mL for single-level fractures and instrumented fusion. Two patients had hardware-related complications. At follow-up (mean 9.67 months after surgery), patients were doing well clinically, and most imaging showed stable alignment.

CONCLUSIONS

Our early experience shows that short segment instrumentation through a minimally invasive approach is a safe and effective surgical option for young pediatric patients with good clinical outcomes and favorable radiographic postoperative finding.

Laminoplasty versus laminectomy with fusion for treating multilevel degenerative cervical myelopathy

Background

Laminectomy with fusion (LF) and laminoplasty (LP) are common posterior decompression procedures used to treat multilevel degenerative cervical myelopathy (DCM). There is debate on their relative efficacy and safety for treatment of DCM. The goal of this study is to examine outcomes and costs of LF and LP procedures for DCM.

Methods

This is a retrospective review of adult patients (<18) at a single center who underwent elective LP and LF of at least 3 levels from C3-C7. Outcome measures included operative characteristics, inpatient mobility status, length of stay, complications, revision surgery, VAS neck pain scores, and changes in radiographic alignment. Oral opioid analgesic needs and hospital cost comparison were also assessed.

Results

LP cohort (n=76) and LF cohort (n=59) reported no difference in neck pain at baseline, 1, 6, 12, and 24 months postoperatively (p>.05). Patients were successfully weaned off opioids at similar rates (LF: 88%, LP: 86%). Fixed and variable costs respectively with LF cases hospital were higher, 15.7% and 25.7% compared to LP cases (p=.03 and p<.001). LF has a longer length of stay (4.2 vs. 3.1 days, p=.001). Wound-related complications were 5 times more likely after LF (13.6% vs. 5.9%, RR: 5.15) and C5 palsy rates were similar across the groups (LF: 11.9% LP: 5.6% RR: 1.8). Ground-level falls requiring an emergency department visit were more likely after LF (11.9% vs. 2.6%, p=.04).

Conclusions

When treating multilevel DCM, LP has similar rates of new or increasing axial neck pain compared to LF. LF was associated with greater hospital costs, length of stay, and complications compared to LP. LP may in fact be a less morbid and more cost-effective alternative to LF for patients without cervical deformity.

Efficacy of Routine Intraoperative Cranio-Femoral Traction in Surgical Treatment of Adolescent Idiopathic Scoliosis Curves Measuring Between 50° and 90°

STUDY DESIGN

Retrospective Comparative Study, Level III.

OBJECTIVE

In patients with scoliosis >90°, cranio-femoral traction (CFT) has been shown to obtain comparable curve correction with decreased operative time and blood loss. Routine intraoperative CFT use in the treatment of AIS <90° has not been established definitively. This study investigates the effectiveness of intraoperative CFT in the treatment of AIS between 50° and 90°, comparing the magnitude of curve correction, blood loss, operative time, and traction-related complications with and without CFT.

METHODS

73 patients with curves less than 90° were identified, 36 without and 37 with cranio-femoral traction. Neuromuscular scoliosis and revision surgery were excluded. Age, preoperative Cobb angles, bending angles, and curve types were recorded. Surgical characteristics were analyzed including number of levels fused, estimated blood loss, operative time, major curve correction (%), and degree of postoperative kyphosis.

RESULTS

Patients with traction had significantly higher preoperative major curves but no difference in age or flexibility. Lenke 1 curves had significantly shorter operative time and improvement in curve correction with traction. Among subjects with 5 to 8 levels fused, subjects with traction had significantly less EBL. Operative time was significantly shorter for subjects with 5-8 levels and 9-11 levels fused. Curves measuring 50°-75° showed improved correction with traction.

CONCLUSION

Intraoperative traction resulted in shorter intraoperative time and greater correction of major curves during surgical treatment of adolescent idiopathic scoliosis less than 90°. Strong considerations should be given to use of intraoperative CFT for moderate AIS.

Sociodemographic Characteristics of Patients Undergoing Surgery for Metastatic Disease of the Spine

INTRODUCTION

Some patients, particularly those who are socioeconomically deprived, are diagnosed with primary and/or metastatic cancer only after presenting to the emergency department. Our objective was to determine sociodemographic characteristics of patients undergoing surgery for metastatic spine disease at our institution.

METHODS

This retrospective case series included patients 18 years and older who presented to the emergency department with metastatic spine disease requiring surgery. Demographics and survival data were collected. Sociodemographic characteristics were estimated using the Social Deprivation Index (SDI) and Area Deprivation Index (ADI) for the state of California. Univariate log-rank tests and Kaplan-Meier curves were used to assess differences in survival for predictors of interest.

RESULTS

Between 2015 and 2021, 64 patients underwent surgery for metastatic disease of the spine. The mean age was 61.0 ± 12.5 years, with 60.9% being male (n = 39). In this cohort, 89.1% of patients were non-Hispanic (n = 57), 71.9% were White (n = 46), and 62.5% were insured by Medicare/Medicaid (n = 40). The mean SDI and ADI were 61.5 ± 28.0 and 7.7 ± 2.2, respectively. 28.1% of patients (n = 18) were diagnosed with primary cancer for the first time while 39.1% of patients (n = 25) were diagnosed with metastatic cancer for the first time. During index hospitalization, 37.5% of patients (n = 24) received palliative care consult. The 3-month, 6-month, and all-time mortality rates were 26.7% (n = 17), 39.5% (n = 23), and 50% (n = 32), respectively, with 10.9% of patients (n = 7) dying during their admission. Payor plan was significant at 3 months ( P = 0.02), and palliative consultation was significant at 3 months ( P = 0.007) and 6 months ( P = 0.03). No notable association was observed with SDI and ADI in quantiles or as continuous variables.

DISCUSSION

In this study, 28.1% of patients were diagnosed with cancer for the first time. Three-month and 6-month mortality rates for patients undergoing surgery were 26.7% and 39.5%, respectively. Furthermore, mortality was markedly associated with palliative care consultation and insurance status, but not with SDI and ADI.

LEVEL OF EVIDENCE

Retrospective case series, Level III evidence.

A Comparison of Prognostic Models to Facilitate Surgical Decision-Making for Patients With Spinal Metastatic Disease

STUDY DESIGN

Retrospective cohort.

OBJECTIVE

Compare the performance of and provide cutoff values for commonly used prognostic models for spinal metastases, including Revised Tokuhashi, Tomita, Modified Bauer, New England Spinal Metastases Score (NESMS), and Skeletal Oncology Research Group model, at three- and six-month postoperative time points.

SUMMARY OF BACKGROUND DATA

Surgery may be recommended for patients with spinal metastases causing fracture, instability, pain, and/or neurological compromise. However, patients with less than three to six months of projected survival are less likely to benefit from surgery. Prognostic models have been developed to help determine prognosis and surgical candidacy. Yet, there is a lack of data directly comparing the performance of these models at clinically relevant time points or providing clinically applicable cutoff values for the models.

MATERIALS AND METHODS

Sixty-four patients undergoing surgery from 2015 to 2022 for spinal metastatic disease were identified. Revised Tokuhashi, Tomita, Modified Bauer, NESMS, and Skeletal Oncology Research Group were calculated for each patient. Model calibration and discrimination for predicting survival at three months, six months, and final follow-up were evaluated using the Brier score and Uno's C, respectively. Hazard ratios for survival were calculated for the models. The Contral and O'Quigley method was utilized to identify cutoff values for the models discriminating between survival and nonsurvival at three months, six months, and final follow-up.

RESULTS

Each of the models demonstrated similar performance in predicting survival at three months, six months, and final follow-up. Cutoff scores that best differentiated patients likely to survive beyond three months included the Revised Tokuhashi score=10, Tomita score=four, Modified Bauer score=three, and NESMS=one.

CONCLUSION

We found comparable efficacy among the models in predicting survival at clinically relevant time points. Cutoff values provided herein may assist surgeons and patients when deciding whether to pursue surgery for spinal metastatic disease.

LEVEL OF EVIDENCE

4.

Patient Characteristics, Injury Types, and Costs Associated with Secondary Over-Triage of Isolated Cervical Spine Fractures

STUDY DESIGN

Retrospective cohort.

OBJECTIVE

To aim of this study was to identify patient variables, injury characteristics, and costs associated with operative and non-operative treatment following inter-facility transfer of patients with isolated cervical spine fractures.

SUMMARY OF BACKGROUND DATA

Patients with isolated cervical spine fractures are subject to inter-facility transfer for surgical assessment, yet are often treated nonoperatively. The American College of Surgeons' benchmark rate of "secondary over-triage" is <50%. Identifying patient and injury characteristics as well as costs associated with treatment following transfer of patients with isolated cervical spine fractures may help reduce rates of secondary over-triage and healthcare expenditures.

METHODS

Patients transferred to a Level-1 trauma center with isolated cervical spine fractures between January 2015 and September 2020 were identified. Patient demographics, comorbidities, insurance data, injury characteristics, imaging workup, treatment, and financial data were collected for all patients. Multivariable logistic regression models were constructed to identify patient and injury characteristics associated with surgical treatment.

RESULTS

Nearly 75% of patients were treated non-operatively. Over 97% of transfers were accepted by the general surgery trauma service. Multivariable modeling found that higher BMI, presence of any neurologic deficit including spinal cord or isolated spinal nerve root injuries, present smoking status, or cervical spine magnetic resonance imaging obtained post-transfer, were associated with surgical treatment for isolated cervical spine fractures. Among patients with type II dens fractures, increased fracture displacement was associated with surgical treatment. Median charges to patients treated operatively and nonoperatively were $380,890 and $90,734, respectively. Median hospital expenditures for patients treated operatively and nonoperatively were $55,115 and $12,131, respectively.

CONCLUSION

A large proportion of patients with isolated cervical spine fractures are subject to over-triage. Injury characteristics are important for determining need for surgical treatment, and therefore interfacility transfer. Improving communication with spine surgeons when deciding to transfer patients may significantly reduce health care costs and resource use.Level of Evidence: 4.

Variability in Opioid Prescription Following Primary Single-Level Lumbar Microdiscectomy

STUDY DESIGN

Retrospective case series.

OBJECTIVES

To evaluate the variability in opioid prescription following primary single-level lumbar microdiscectomy.

METHODS

We retrospectively reviewed consecutive patients who underwent primary single-level lumbar microdiscectomy. Only opioid-naïve patients ≥18 years old were included. Patients who had revision microdiscectomy, multilevel decompression, and/or any complication requiring prolonged hospital stay (>2 days) were excluded. The primary outcomes were the maximum daily dosage of opioids prescribed in morphine milligram equivalents (MME) and the number of pills prescribed (equivalent to 5 mg hydrocodone).

RESULTS

Between 2014 and 2019, 169 patients (90 men, 79 women) met inclusion criteria, with a mean age of 46.9 years. Surgery resulted in a statistically significant improvement in VAS (Visual Analogue Scale) score (6.4 to 2.5, P < .01). At discharge, 8 patients (4.7%) did not receive any opioid prescription. Of the remaining 161 patients, 1 patient (0.01%) received hydromorphone, 30 (18.6%) Percocet, 43 (26.7%) oxycodone, and 87 Norco (54.0%). The length of opioid prescription was 6.7 days. The maximum daily dosage of opioids prescribed was 70.4 MME (SD 32.1). The total number of pills prescribed was 89.4 (SD 54.7). Twenty-five patients (15.5%) received a refill prescription. Multivariate analysis demonstrated the operating service, prescriber, and hospital admission were statistically significant predictors of maximum daily MME. The prescriber and hospital admission were statistically significant predictors of total number of pills prescribed.

CONCLUSIONS

We found significant variability in opioid prescription following primary single-level lumbar microdiscectomy. For standard spinal procedures like lumbar microdiscectomy, opioid-prescribing guidelines should be established to standardize postoperative pain management.

Sarcopenia Is an Independent Risk Factor for Proximal Junctional Disease Following Adult Spinal Deformity Surgery

STUDY DESIGN

Retrospective cohort study.

OBJECTIVES

Sarcopenia is a risk factor for medical complications following spine surgery. However, the role of sarcopenia as a risk factor for proximal junctional disease (PJD) remains undefined. This study evaluates whether sarcopenia is an independent predictor of proximal junctional kyphosis (PJK) and proximal junctional failure (PJF) following adult spinal deformity (ASD) surgery.

METHODS

ASD patients who underwent thoracic spine to pelvis fusion with 2-year clinical and radiographic follow-up were reviewed for development of PJK and PJD. Average psoas cross-sectional area on preoperative axial computed tomography or magnetic resonance imaging at L4 was recorded. Previously described PJD risk factors were assessed for each patient, and multivariate linear regression was performed to identify independent risk factors for PJK and PJF. Disease-specific thresholds were calculated for sarcopenia based on psoas cross-sectional area.

RESULTS

Of 32 patients, PJK and PJF occurred in 20 (62.5%) and 12 (37.5%), respectively. Multivariate analysis demonstrated psoas cross-sectional area to be the most powerful independent predictor of PJK (P = .02) and PJF (P = .009). Setting ASD disease-specific psoas cross-sectional area thresholds of <12 cm² in men and <8 cm² in women resulted in a PJF rate of 69.2% for patients below these thresholds, relative to 15.8% for those above the thresholds.

CONCLUSIONS

Sarcopenia is an independent, modifiable predictor of PJK and PJF, and is easily assessed on standard preoperative computed tomography or magnetic resonance imaging. Surgeons should include sarcopenia in preoperative risk assessment and consider added measures to avoid PJF in sarcopenic patients.

Minimally Invasive Lateral Corpectomy of the Thoracolumbar Spine: A Case Series of 20 Patients

STUDY DESIGN

Retrospective case series.

OBJECTIVE

To report our experience with corpectomy of the thoracolumbar (TL) spine through a minimally invasive lateral retropleural or retroperitoneal approach.

METHODS

This is a retrospective case series of 20 consecutive patients who underwent minimally invasive TL corpectomy and spinal reconstruction. Electronic medical records were reviewed for demographic, operative, and clinical outcome data.

RESULTS

Between 2015 and 2019, 20 consecutive cases of minimally invasive TL corpectomy were performed, comprising 12 men (60%) and 8 women (40%) with a mean age of 54.3 years. Indications for surgery were infection (n = 6, 30%), metastatic disease (n = 2, 10%), fracture (n = 6, 30%), and calcified disc herniation (n = 6, 30%). Partial and complete corpectomy was performed in 5 patients (25%) and 15 patients (75%), respectively. Mean operative time and estimated blood loss was 276.2 minutes and 558.4 mL, respectively. Mean length of stay from admission and surgery were 14.6 and 11.4 days, respectively. Mean length of stay from surgery for elective cases was 4.2 days. Mean follow-up time was 330.4 days. Visual analogue scale score improved from 7.7 to 4.5 (P < .01). There were a total of 3 postoperative complications in 2 patients, including 1 mortality for urosepsis. One patient had revision spinal surgery for adjacent segment disease.

CONCLUSIONS

Corpectomy and reconstruction of the TL spine is feasible and safe using a minimally invasive lateral retropleural or retroperitoneal approach. Since this is a relatively new technique, more studies are needed to compare the short- and long-term radiographic and clinical outcomes between minimally invasive versus open corpectomy of the TL spine.

High- versus low-dose tranexamic acid as part of a Patient Blood Management strategy for reducing blood loss in patients undergoing surgery for adolescent idiopathic scoliosis

PURPOSE

The administration of tranexamic acid (TXA) has been shown to be beneficial in reducing blood loss during surgery for adolescent idiopathic scoliosis (AIS), but optimal dosing has yet to be defined. This retrospective study compared high- versus low-dose TXA as part of a Patient Blood Management strategy for reducing blood loss in patients undergoing posterior spine fusion surgery.

METHODS

Clinical records were reviewed for 223 patients with AIS who underwent posterior spinal fusion of five or more levels during a 6-year time period. We compared normalized blood loss, total estimated blood loss (EBL), and the need for transfusion between patients receiving high-dose TXA (loading dose of ≥ 30 mg/kg) versus low-dose TXA (loading dose < 30 mg/kg). Both groups received maintenance TXA infusions of 10 mg/kg/h until skin closure.

RESULTS

Patient demographics, curves, and surgical characteristics were similar in both groups. The high-dose TXA group had a 36% reduction in normalized blood loss (1.8 cc/kg/level fused versus 2.8 cc/kg/level fused, p < 0.001) and a 37.5% reduction in total EBL (1000 cc versus 1600 cc, p < 0.001). Patients in the high-dose group had a 48% reduction in PRBC transfusion, with only 19% receiving a transfusion of PRBC compared to 67% in the low-dose group (p < 0.001).

CONCLUSION

When combined with other proven Patient Blood Management strategies, the use of high-dose TXA compared to low-dose TXA may be beneficial in reducing blood loss for patients with adolescent idiopathic scoliosis undergoing posterior spinal fusion surgery.

LEVEL OF EVIDENCE

Level III, retrospective cohort.

Ligament Augmentation With Mersilene Tape Reduces the Rates of Proximal Junctional Kyphosis and Failure in Adult Spinal Deformity

OBJECTIVE

To investigate prevention of proximal junctional kyphosis (PJK) and failure (PJF) following adult spinal deformity (ASD) surgery utilizing a novel technique of posterior ligament augmentation with polyester fiber tether.

METHODS

This study evaluated ASD adult patients who underwent posterior decompression and instrumented fusion from the thoracolumbar junction (T9-L1) to the pelvis from 2011-2017. Basic demographic data were obtained. Radiographic outcomes included proximal junctional angle (PJA), sagittal vertical axis, PJK, and PJF. The study population was divided into patients who had ASD surgery with and without ligamentous augmentation.

RESULTS

A total of 43 subjects were evaluated, including 20 without and 23 with ligamentous augmentation. PJA increased over time for both groups. PJA was smaller for the augmented group, and rate of increase in PJA was slower in the augmented group (p < 0.0001). The rate of PJK was significantly higher in the nonaugmented group (p = 0.01). PJF was significantly less common in the augmented group (p = 0.003). Time to revision surgery was lower in the nonaugmented group (p = 0.003).

CONCLUSION

Our novel ligament augmentation technique utilizing polyethylene tape is an effective technique to slow progression of the PJA and lower the risk for proximal junctional disease in ASD surgery.

Efficacy, Cost, and Complications of Demineralized Bone Matrix in Instrumented Lumbar Fusion: Comparison With rhBMP-2

STUDY DESIGN

Retrospective cohort study.

OBJECTIVES

To evaluate demineralized bone matrix as an adjunct for instrumented lumbar spine fusion compared with recombinant human bone morphogenetic protein-2 (rhBMP-2).

METHODS

Clinical and radiographic review was performed of 43 patients with degenerative spine disease treated with posterolateral spinal fusion with or without posterior or transforaminal lumbar interbody fusion. Final analysis included sixteen patients treated with demineralized bone matrix (DBM; Accell Evo3, SeaSpine) compared with a retrospective matched group of 21 patients treated with rhBMP-2 (rhBMP-2, Infuse, Medtronic). All patients were followed for 24 months. Fusion was evaluated by computed tomography and/or x-ray. Clinical outcomes included visual analogue scale (VAS), Oswestry Disability Index (ODI), and Short Form 12 (SF-12).

RESULTS

Overall fusion rate, including posterolateral and/or interbody fusion, was 100% for both groups, though the fusion rates in the posterolateral space alone were 93.5% and 100% for the DBM and rhBMP-2 groups, respectively. Clinical outcomes were similar between groups, with the DBM group showing greater improvement in ODI. The rhBMP-2 group showed higher rates of radiographic complications with 7 of 21 patients (33.3%) demonstrating either adjacent level fusion or ectopic bone formation, compared with zero in the DBM group. Average biologic cost per level was $1522 for DBM and $3505 for rhBMP-2.

CONCLUSIONS

DBM and rhBMP-2 demonstrated similar radiographic and clinical outcomes in instrumented lumbar fusions. rhBMP-2 was associated with higher rates of radiographic complications and significantly higher costs.

Clinical and Radiographic Comparison Between Open Versus Minimally Invasive Transforaminal Lumbar Interbody Fusion With Bilateral Facetectomies

STUDY DESIGN

Age- and sex-matched cohort study.

OBJECTIVES

To compare outcomes after open versus minimally invasive transforaminal lumbar interbody fusion (MIS-TLIF) with bilateral facetectomies.

METHODS

We retrospectively compared patients who underwent single- or 2-level MIS-TLIF with an age- and sex-matched open-TLIF cohort. Surgical data was collected for operative time, estimated blood loss (EBL), and drain use. Clinical outcomes included the Visual Analog Scale (VAS), Oswestry Disability Index (ODI), length of stay (LOS), complications, and reoperations. Lumbar radiographs were measured for changes in global lumbar lordosis (LL) and segmental lordosis (SL).

RESULTS

Between 2016 and 2020, 38 MIS-TLIF patients were compared with 38 open-TLIF patients. No subfascial drain was used in the MIS-TLIF group (P < .001). The MIS-TLIF group had longer operative time (310.8 vs 276.5 minutes; P = .046) but less EBL (282.4 vs 420.8 mL; P = .007). LOS (P = .15), complication rates (P = .50), and revision rates (P = .17) were equivalent. VAS and ODI improved but did not differ between groups. In the open-TLIF group, LL and SL were restored or improved in 81.6% and 86.9% of cases, respectively. In the MIS-TLIF group, LL and SL were restored or improved in 86.8% and 97.4% of cases, respectively. There were no differences in changes in LL and SL between groups.

CONCLUSIONS

Compared with the age- and sex-matched open-TLIF cohort, patients undergoing MIS-TLIF had reduced EBL and subfascial drain use but increased operative time. There were no differences in complications, reoperations, or LOS. Both groups demonstrated improvement in VAS and ODI. MIS-TLIF with bilateral facetectomies provided equivalent improvements in global and segmental LL.

The Utility of Magnetic Resonance Imaging for Detecting Unstable Cervical Spine Injuries in the Neurologically Intact Traumatized Patient Following Negative Computed Tomography Imaging

BACKGROUND

Neurologically intact blunt trauma patients with persistent neck pain and negative computed tomography (CT) imaging frequently undergo magnetic resonance imaging (MRI) for evaluation of occult cervical spine injury. There is a paucity of data to support or refute this practice. This study was therefore performed to evaluate the utility of cervical spine MRI in neurologically intact blunt trauma patients with negative CT imaging.

METHODS

A retrospective review was performed of all neurologically intact blunt trauma patients presenting to a level 1 trauma center from 2005 to 2015 with persistent neck pain and negative CT imaging. The proportion of patients with positive MRI findings, subsequent treatment, and time required to obtain MRI results was evaluated.

RESULTS

Of 223 patients meeting inclusion criteria, 11 had positive MRI findings; however, no patients were found to have unstable injuries requiring surgical treatment. The process for a complete evaluation of unstable cervical spine injury from the time of obtaining a CT scan was 19 hours and 43 minutes.

CONCLUSIONS

Eleven patients had positive MRI findings, yet these findings did not alter treatment. In contrast, the time required to obtain MRI results may substantially delay patient care.

LEVEL OF EVIDENCE

IV (retrospective case series) CLINICAL RELEVANCE: Our results demonstrate that MRI has limited utility in neurologically intact blunt trauma patients with negative CT imaging.

Povidone-iodine irrigation combined with Vancomycin powder lowers infection rates in pediatric deformity surgery

BACKGROUND

Surgical site infection is a morbid, devastating complication after spinal procedures. Studies have investigated the effect of wound lavage with 3.5% Povidone-iodine solution or the use of intrawound Vancomycin powder. We examined the effect of Povidone-iodine irrigation, intrawound Vancomycin powder, or a combination of both agents in a tertiary care Pediatric Hospital.

METHODS

We queried our health system database for patients undergoing spinal surgery over an eight-year span between January 2008 and June 2016 and identified patient cohorts who received no intervention, intrawound Vancomycin alone, Povidone-iodine irrigation alone, or a combination of both agents. Infection rates were determined. The effect of treatment on outcome was analyzed using a logistic regression model.

RESULTS

475 patients were identified who met study inclusion criteria. 88 non-neuromuscular patients received no intra-operative agent. The surgical site infection (SSI) rate in this group of patients was 10%. For the 194 non-neuromuscular scoliosis patients who received Povidone-iodine and Vancomycin powder, the infection rate was reduced to 0.7%. The SSI rate in the 180 non-neuromuscular patients who were treated with Vancomycin powder alone was 1.4%. 13 patients were treated with Povidone-iodine lavage only, with a small sample size precluding statistical comparison. Infection rate in the 132 neuromuscular disease patients decreased from 14 to 7% overall during this time span: while the odds ratio of infection was reduced in all neuromuscular treatment groups receiving intra-operative measures, statistical significance was not reached in any neuromuscular group studied.

CONCLUSIONS

A protocol using combined 3.5% weight/volume Povidone-iodine and Vancomycin powder was associated with the lowest infection rate in our non-neuromuscular patient population and should be considered as a low cost intervention in pediatric patients undergoing spinal deformity procedures.

LEVEL OF EVIDENCE

Level II.

Safety and Efficacy of Power-Assisted Pedicle Tract Preparation and Screw Placement

STUDY DESIGN

Retrospective review of 1 surgeon's posterior spinal fusion cases.

OBJECTIVES

To assess the safety and efficacy of using power tools versus using manual tools to create pedicle tracts and place pedicle screws.

SUMMARY OF BACKGROUND DATA

This is the first study to report on the safety and efficacy of pedicle tract creation and pedicle screw placement using power tools.

METHODS

The study included 442 cases and 6412 pedicle screws. The manual tool cohort included 159 cases (1,870 screws, January 1, 2004 to June 30, 2007). The power tool cohort included 283 cases (4,542 screws, January 1, 2008 to August 29, 2012). Patient charts and radiographs were reviewed. The researchers recorded the number of screws placed and their positions. Screws were classified as failed if the patient returned to surgery for revision or removal of the screw. Operating and fluoroscopy times were analyzed by cohort overall and for diagnosis-specific subsets.

RESULTS

The incidence of injury resulting from pedicle screw placement was 0.00% (0 of 1,870) with the manual method and 0.02% (1 of 4,542) with power (p = .5211). One screw, placed with power, was assumed to have caused a minor hemothorax, which was successfully treated with a chest tube. There were no neurologic or vascular injuries or other complications attributable to a pedicle screw in either group. Screws placed with power were removed or revised because of problems attributable to the pedicle screw one-sixth as often as those placed using manual tools: 2 of 1,410 (0.14%) versus 8 of 948 (0.84%) (p = .024). Fluoroscopy times in the power cohort were two-thirds as long as those in the manual cohort (p < .001). Operating times were not significantly different (p = .109).

CONCLUSIONS

The use of power tools to create pedicle tracts and place pedicle screws was associated with shorter fluoroscopy times and a lower revision rate compared with using manual tools. Both techniques posed similar low risks of injury to the patient.

Combinatorial roles for BMPs and Endothelin 1 in patterning the dorsal-ventral axis of the craniofacial skeleton

Bone morphogenetic proteins (BMPs) play crucial roles in craniofacial development but little is known about their interactions with other signals, such as Endothelin 1 (Edn1) and Jagged/Notch, which pattern the dorsal-ventral (DV) axis of the pharyngeal arches. Here, we use transgenic zebrafish to monitor and perturb BMP signaling during arch formation. With a BMP-responsive transgene, Tg(Bre:GFP), we show active BMP signaling in neural crest (NC)-derived skeletal precursors of the ventral arches, and in surrounding epithelia. Loss-of-function studies using a heat shock-inducible, dominant-negative BMP receptor 1a [Tg(hs70I:dnBmpr1a-GFP)] to bypass early roles show that BMP signaling is required for ventral arch development just after NC migration, the same stages at which we detect Tg(Bre:GFP). Inhibition of BMP signaling at these stages reduces expression of the ventral signal Edn1, as well as ventral-specific genes such as hand2 and dlx6a in the arches, and expands expression of the dorsal signal jag1b. This results in a loss or reduction of ventral and intermediate skeletal elements and a mis-shapen dorsal arch skeleton. Conversely, ectopic BMP causes dorsal expansion of ventral-specific gene expression and corresponding reductions/transformations of dorsal cartilages. Soon after NC migration, BMP is required to induce Edn1 and overexpression of either signal partially rescues ventral skeletal defects in embryos deficient for the other. However, once arch primordia are established the effects of BMPs become restricted to more ventral and anterior (palate) domains, which do not depend on Edn1. This suggests that BMPs act upstream and in parallel to Edn1 to promote ventral fates in the arches during early DV patterning, but later acquire distinct roles that further subdivide the identities of NC cells to pattern the craniofacial skeleton.

Requirements for endoderm and BMP signaling in sensory neurogenesis in zebrafish

Cranial sensory neurons largely derive from neurogenic placodes (epibranchial and dorsolateral), which are ectodermal thickenings that form the sensory ganglia associated with cranial nerves, but the molecular mechanisms of placodal development are unclear. Here, we show that the pharyngeal endoderm induces epibranchial neurogenesis in zebrafish, and that BMP signaling plays a crucial role in this process. Using a her5:egfp transgenic line to follow endodermal movements in living embryos, we show that contact between pharyngeal pouches and the surface ectoderm coincides with the onset of neurogenesis in epibranchial placodes. By genetic ablation and reintroduction of endoderm by cell transplantation, we show that these contacts promote neurogenesis. Using a genetic interference approach we further identify bmp2b and bmp5 as crucial components of the endodermal signals that induce epibranchial neurogenesis. Dorsolateral placodes (trigeminal, auditory, vestibular, lateral line) develop independently of the endoderm and BMP signaling, suggesting that these two sets of placodes are under separate genetic control. Our results show that the endoderm regulates the differentiation of cranial sensory ganglia, which coordinates the cranial nerves with the segments that they innervate.

Hedgehog signaling is required for cranial neural crest morphogenesis and chondrogenesis at the midline in the zebrafish skull

Neural crest cells that form the vertebrate head skeleton migrate and interact with surrounding tissues to shape the skull, and defects in these processes underlie many human craniofacial syndromes. Signals at the midline play a crucial role in the development of the anterior neurocranium, which forms the ventral braincase and palate, and here we explore the role of Hedgehog (Hh) signaling in this process. Using sox10:egfp transgenics to follow neural crest cell movements in the living embryo, and vital dye labeling to generate a fate map, we show that distinct populations of neural crest form the two main cartilage elements of the larval anterior neurocranium: the paired trabeculae and the midline ethmoid. By analyzing zebrafish mutants that disrupt sonic hedgehog (shh) expression, we demonstrate that shh is required to specify the movements of progenitors of these elements at the midline, and to induce them to form cartilage. Treatments with cyclopamine, to block Hh signaling at different stages, suggest that although requirements in morphogenesis occur during neural crest migration beneath the brain, requirements in chondrogenesis occur later, as cells form separate trabecular and ethmoid condensations. Cell transplantations indicate that these also reflect different sources of Shh, one from the ventral neural tube that controls trabecular morphogenesis and one from the oral ectoderm that promotes chondrogenesis. Our results suggest a novel role for Shh in the movements of neural crest cells at the midline, as well as in their differentiation into cartilage, and help to explain why both skeletal fusions and palatal clefting are associated with the loss of Hh signaling in holoprosencephalic humans.

AP2-dependent signals from the ectoderm regulate craniofacial development in the zebrafish embryo

AP2 transcription factors regulate many aspects of embryonic development. Studies of AP2a (Tfap2a) function in mice and zebrafish have demonstrated a role in patterning mesenchymal cells of neural crest origin that form the craniofacial skeleton, while the mammalian Tfap2b is required in both the facial skeleton and kidney. Here, we show essential functions for zebrafish tfap2a and tfap2b in development of the facial ectoderm, and for signals from this epithelium that induce skeletogenesis in neural crest cells (NCCs). Zebrafish embryos deficient for both tfap2a and tfap2b show defects in epidermal cell survival and lack NCC-derived cartilages. We show that cartilage defects arise after NCC migration during skeletal differentiation, and that they can be rescued by transplantation of wild-type ectoderm. We propose a model in which AP2 proteins play two distinct roles in cranial NCCs: an early cell-autonomous function in cell specification and survival, and a later non-autonomous function regulating ectodermal signals that induce skeletogenesis

Skeletal and pigment cell defects in the lockjaw mutant reveal multiple roles for zebrafish tfap2a in neural crest development

Members of the AP-2 transcription factor family have critical roles in many aspects of embryonic development. The zebrafish tfap2a mutant lockjaw (low) displays defects in skeletal and pigment cell derivatives of the neural crest. Here we show essential roles for tfap2a in subsets of embryonic cartilages and pigment cells. Defects in cartilage of the hyoid arch in low correlate with a loss of Hox group 2 gene expression and are suggestive of a transformation to a mandibular fate. In contrast, loss of joints in the mandibular arch and defects in certain types of pigment cells suggest a requirement for tfap2a independent of Hox regulation. Early melanophores do not develop in low mutants, and we propose that this results in part from a loss of kit function, leading to defects in migration, as well as kit-independent defects in melanophore specification. Iridophores are also reduced in low, in contrast to xanthophores, revealing a role for tfap2a in the development of pigment subpopulations. We propose a model of tfap2a function in the neural crest in which there are independent functions for tfap2a in specification of subpopulations of pigment cells and segmental patterning of the pharyngeal skeleton through the regulation of Hox genes. Developmental Dynamics 229:87-98, 2004.

lockjawencodes a zebrafishtfap2arequired for early neural crest development

The neural crest is a uniquely vertebrate cell type that gives rise to much of the craniofacial skeleton, pigment cells and peripheral nervous system, yet its specification and diversification during embryogenesis are poorly understood. Zebrafish homozygous for the lockjaw (low)mutation show defects in all of these derivatives and we show that low (allelic with montblanc) encodes a zebrafish tfap2a, one of a small family of transcription factors implicated in epidermal and neural crest development. A point mutation in lowtruncates the DNA binding and dimerization domains of tfap2a, causing a loss of function. Consistent with this, injection of antisense morpholino oligonucleotides directed against splice sites in tfap2a into wild-type embryos produces a phenotype identical to low. Analysis of early ectodermal markers revealed that neural crest specification and migration are disrupted in low mutant embryos. TUNEL labeling of dying cells in mutants revealed a transient period of apoptosis in crest cells prior to and during their migration. In the cranial neural crest, gene expression in the mandibular arch is unaffected in low mutants, in contrast to the hyoid arch, which shows severe reductions in dlx2 and hoxa2 expression. Mosaic analysis, using cell transplantation,demonstrated that neural crest defects in low are cell autonomous and secondarily cause disruptions in surrounding mesoderm. These studies demonstrate that low is required for early steps in neural crest development and suggest that tfap2a is essential for the survival of a subset of neural crest derivatives.