A novel model to evaluate the fatigue resistance of NiTi instruments: Rotational and axial movement at body temperature.

To develop a model to test cyclic fatigue resistance of TruNatomy instruments undergoing rotational and axial movement at body temperature. A total of 288 Prime and Medium instruments were subjected to cyclic fatigue testing in simulated canals (at 37°C) using a model with either rotational movement only or rotational and axial movement simultaneously. Two different sized canals and three different types of curvatures were tested for each instrument (30/0.04 and 30/0.06 for Prime; 38/0.04 and 40/0.06 for Medium). The number of cycles to failure (fatigue resistance) was recorded. Rotational and axial movement of instruments led to greater fatigue resistance compared with rotational movement alone. Apical curvatures led to greater fatigue resistance than curvatures in the coronal and middle third. The developed dynamic model at body temperature to evaluate fatigue resistance of instrument closer simulates clinical scenarios.

Reasons why adults do not seek treatment for acne: a survey of university students and staff.

BACKGROUND: Acne can be a highly debilitating disease. There is a high prevalence in adults, yet treatment rates in this population are low. OBJECTIVES: An online survey was created to determine the main reasons why adults with acne do not seek treatment. METHODS: University students and staff 20 years of age and older were emailed a link to an online survey that asked them if they have facial acne, if they see a provider for it, and how they self-treat their acne. RESULTS: 1,136 complete surveys were returned. Top reasons for not seeing a provider include not being bothered enough to seek treatment (n = 418, 53.7%), believing that their acne will eventually resolve on its own (n = 351, 45.1%), concerned about costs of treatment (n = 274, 35.2%), and currently satisfied with over-the-counter (OTC) treatment (n = 261, 33.5%). CONCLUSION: Most adults with acne do not see providers because they are not bothered enough by it or are satisfied with OTC treatments. However, of the population that has acne and does not seek treatment, a significant portion (n = 234, 30.1%) indicated it was for a reason that could be classified as a treatment barrier.

SARS-CoV-2 specific memory T cell epitopes identified in COVID-19-recovered subjects.

The COVID-19 pandemic caused by SARS-CoV-2 infection poses a serious threat to public health. An explicit investigation of COVID-19 immune responses, particularly the host immunity in recovered subjects, will lay a foundation for the rational design of therapeutics and/or vaccines against future coronaviral outbreaks. Here, we examined virus-specific T cell responses and identified T cell epitopes using peptides spanning SARS-CoV-2 structural proteins. These peptides were used to stimulate peripheral blood mononuclear cells (PBMCs) derived from COVID-19-recovered subjects, followed by an analysis of IFN-γ-secreting T cells by enzyme-linked immunosorbent spot (ELISpot). We also evaluated virus-specific CD4 or CD8 T cell activation by flow cytometry assay. By screening 52 matrix pools (comprised of 315 peptides) of the spike (S) glycoprotein and 21 matrix pools (comprised of 102 peptides) spanning the nucleocapsid (N) protein, we identified 28 peptides from S protein and 5 peptides from N protein as immunodominant epitopes. The immunogenicity of these epitopes was confirmed by a second ELISpot using single peptide stimulation in memory T cells, and they were mapped by HLA restrictions. Notably, SARS-CoV-2 specific T cell responses positively correlated with B cell IgG and neutralizing antibody responses to the receptor-binding domain (RBD) of the S protein. Our results demonstrate that defined levels of SARS-CoV-2 specific T cell responses are generated in some, but not all, COVID-19-recovered subjects, fostering hope for the protection of a proportion of COVID-19-exposed individuals against reinfection. These results also suggest that these virus-specific T cell responses may induce protective immunity in unexposed individuals upon vaccination, using vaccines generated based on the immune epitopes identified in this study. However, SARS-CoV-2 S and N peptides are not potently immunogenic, and none of the single peptides could universally induce robust T cell responses, suggesting the necessity of using a multi-epitope strategy for COVID-19 vaccine design.

Observed patterns of cervical radiculopathy: how often do they differ from a standard, "Netter diagram" distribution?

BACKGROUND CONTEXT: Traditionally, cervical radiculopathy is thought to present with symptoms and signs in a standard, textbook, reproducible pattern as seen in a "Netter diagram." To date, no study has directly examined cervical radicular patterns attributable to single level pathology in patients undergoing ACDF. PURPOSE: The purpose of this study is to examine cervical radiculopathy patterns in a surgical population and determine how often patients present with the standard textbook (ie, Netter diagram) versus nonstandard patterns. STUDY DESIGN/SETTING: A retrospective study. PATIENT SAMPLE: Patients who had single-level radiculopathy with at least 75% improvement of preoperative symptoms following ACDF were included. OUTCOME MEASURES: Epidemiologic variables were collected including age, sex, weight, body mass index, laterality of symptoms, duration of symptoms prior to operative intervention, and the presence of diabetes mellitus. The observed pattern of radiculopathy at presentation, including associated neck, shoulder, upper arm, forearm, and hand pain and/or numbness, was determined from chart review and patient-derived pain diagrams. METHODS: We identified all patients with single level cervical radiculopathy operated on between March 2011 and March 2016 by six surgeons. The observed pattern of radiculopathy was compared to a standard textbook pattern of radiculopathy that strictly adheres to a dermatomal map Fisher exact test was used to analyze categorical data and Student t test was used for continuous variables. A one-way ANOVA was used to determine differences in the observed versus expected radicular pattern. A logistic regression model assessed the effect of demographic variables on presentation with a nonstandard radicular pattern. RESULTS: Overall, 239 cervical levels were identified. The observed pattern of pain and numbness followed the standard pattern in only 54% (129 of 239; p=.35). When a nonstandard radicular pattern was present, it differed by 1.68 dermatomal levels from the standard (p<.0001). Neck pain on the radiculopathy side was the most prevalent symptom; it was found in 81% (193 of 239) of patients and did not differ by cervical level (p=.72). In a logistic regression model, none of the demographic variables of interest were found to significantly impact the likelihood of presenting with a nonstandard radicular pattern. CONCLUSIONS: Observed patterns of cervical radiculopathy only followed the standard pattern in 54% of patients and did not differ by the cervical level involved. Cervical radiculopathy often presents with a nonstandard pattern. Surgeons should think broadly when identifying causative levels because they frequently may not adhere to textbook descriptions in actual clinical practice. We observed III level of evidence.

Is Cervical Bracing Necessary After One- and Two-Level Instrumented Anterior Cervical Discectomy and Fusion? A Prospective Randomized Study.

STUDY DESIGN: Prospective randomized control trial. OBJECTIVE: To investigate the role of cervical collars in postoperative care following 1- and 2-level instrumented anterior cervical discectomy and fusion (ACDF). METHODS: The Cervical Spine Research Society Resident Fellow Grant funded this project. Fifty consecutive patients undergoing 1- or 2-level ACDF surgery were randomized into groups receiving either no brace or a cervical brace for 6 weeks postoperatively. Neck Disability Index scores were recorded preoperatively and at regular follow-up visits up to 1 year. Computed tomography scans were read 1 year postoperatively to determine fusion rates, and subsidence was measured as change in middle vertebral distance between initial postoperative and 6-month follow-up lateral cervical radiographs. RESULTS: Twenty-two patients were in the no-brace group, and 22 patients were in the brace group at final follow-up, with an average age of 50 and 55 years, respectively. The no-brace group had a total of 32 operative levels, whereas the brace group had 38 operative levels. There was no statistically significant difference in 1-year postoperative Neck Disability Index scores between the brace (9.30) and no-brace (6.95) groups (P = .28), in 6-month subsidence of all operative levels between the brace (0.85 mm) and no-brace (0.79 mm) groups (P = .72), or in the proportion of fused levels between the brace (89%) and no-brace (97%) groups (P = .37). CONCLUSIONS: Our results suggest no advantage in wearing a cervical brace following 1- or 2-level ACDF surgery with respect to 1-year outcome scores, 1-year fusion rates, and 6-month subsidence.

Accuracy of Percutaneous Pedicle Screw Placement: Does Training Level Matter?

STUDY DESIGN: In vitro human cadaveric surgical technique study. OBJECTIVE: To assess the accuracy of percutaneous pedicle screw placement in a human cadaveric model using standard fluoroscopic guidance technique, compared across varying levels of experience. SUMMARY OF BACKGROUND DATA: The current literature varies widely in the reported frequency of facet violation during placement of percutaneous pedicle screws. However, as of yet there are no studies examining the effect that training level has on accuracy of placement. MATERIALS AND METHODS: Four surgeons with differing levels of training (PGY-2, PGY-4, fellow, attending) were evaluated on their accuracy of percutaneous placement of screws in a uniform manner. Each of the 10 cadavers was instrumented from L1 to S1 bilaterally, for a total of 120 screws. Specimens were dissected to evaluate for facet and pedicle wall violations. These were then recorded and analyzed to evaluate for correlation among participating surgeons, laterality, spinal level, and cadaver body mass index. RESULTS: Of 120 screws placed, there were 35 total violations [26 superior articular facet violations (21.7%), 5 intra-articular facet joint violations (4.2%), and 4 pedicle breaches (3.3%)]. Among the trainees there was no difference in the likelihood of causing a violation (P=0.8863) but there was a difference when compared with the attending surgeon (P=0.0175). Laterality (P=0.1598), spinal level (P=0.3536), and body mass index (P=0.8547) did not correlate with the likelihood of a violation. CONCLUSIONS: Surgeons of differing training levels are able to safely and accurately place lumbar pedicle screws in a percutaneous manner, with a low likelihood of facet and pedicle wall violations.

Rare Complications of Cervical Spine Surgery: Horner's Syndrome.

STUDY DESIGN: A multicenter retrospective case series. OBJECTIVE: Horner's syndrome is a known complication of anterior cervical spinal surgery, but it is rarely encountered in clinical practice. To better understand the incidence, risks, and neurologic outcomes associated with Horner's syndrome, a multicenter study was performed to review a large collective experience with this rare complication. METHODS: We conducted a retrospective multicenter case series study involving 21 high-volume surgical centers from the AOSpine North America Clinical Research Network. Medical records for 17 625 patients who received subaxial cervical spine surgery from 2005 to 2011 were reviewed to identify occurrence of 21 predefined treatment complications. Descriptive statistics were provided for baseline patient characteristics. Paired t test was used to analyze changes in clinical outcomes at follow-up compared to preoperative status. RESULTS: In total, 8887 patients who underwent anterior cervical spine surgery at the participating institutions were screened. Postoperative Horner's syndrome was identified in 5 (0.06%) patients. All patients experienced the complication following anterior cervical discectomy and fusion. The sympathetic trunk appeared to be more vulnerable when operating on midcervical levels (C5, C6), and most patients experienced at least a partial recovery without further treatment. CONCLUSIONS: This collective experience suggests that Horner's syndrome is an exceedingly rare complication following anterior cervical spine surgery. Injury to the sympathetic trunk may be limited by maintaining a midline surgical trajectory when possible, and performing careful dissection and retraction of the longus colli muscle when lateral exposure is necessary, especially at caudal cervical levels.

Recurrent Laryngeal Nerve Palsy After Cervical Spine Surgery: A Multicenter AOSpine Clinical Research Network Study.

STUDY DESIGN: Multicenter retrospective study. OBJECTIVES: To investigate the risk of symptomatic recurrent laryngeal nerve palsy (RLNP) following cervical spine surgery, to examine risk factors for its development, and to report its treatment and outcomes. METHODS: A multicenter study from 21 high-volume surgical centers from the AOSpine North America Clinical Research Network was performed. Each center screened for rare complications following cervical spine surgery, including RLNP. Patients were included if they underwent cervical spine surgery (levels from C2 to C7) between January 1, 2005 and December 31, 2011. Data were analyzed with regard to complication treatment and outcome. Cases were compared to a control group from the AOSpine CSM and CSM-I studies. RESULTS: Three centers reported 19 cases of RLNP from a cohort of 1345 patients. The reported incidence of RLNP ranged from 0.6% to 2.9% between these 3 centers. Fifteen patients (79%) in the RLNP group were approached from the left side. Ten patients (52.6%) required treatment for RLNP-6 required medical therapy (steroids), 1 interventional treatment (injection laryngoplasty), and 3 conservative therapy (speech therapy). When examining outcomes, 73.7% (14/19) of cases resolved completely, 15.8% (3/19) resolved with residual effects, and in 10.5% (2/19) of cases this could not be determined. CONCLUSIONS: In this multicenter study examining rare complications following cervical spine surgery, the risk of RLNP after cervical spine surgery ranged from 0.6% to 2.9% between centers. Though rare, it was found that 16% of patients may experience partial resolution with residual effects, and 74% resolve completely.

A Multicenter Study of the Presentation, Treatment, and Outcomes of Cervical Dural Tears.

STUDY DESIGN: Retrospective multicenter case series study. OBJECTIVE: Because cervical dural tears are rare, most surgeons have limited experience with this complication. A multicenter study was performed to better understand the presentation, treatment, and outcomes following cervical dural tears. METHODS: Multiple surgeons from 23 institutions retrospectively identified 21 rare complications that occurred between 2005 and 2011, including unintentional cervical dural tears. Demographic data and surgical history were obtained. Clinical outcomes following surgery were assessed, and any reoperations were recorded. Neck Disability Index (NDI), modified Japanese Orthopaedic Association (mJOA), Nurick classification (NuC), and Short-Form 36 (SF36) scores were recorded at baseline and final follow-up at certain centers. All data were collected, collated, and analyzed by a private research organization. RESULTS: There were 109 cases of cervical dural tears among 18 463 surgeries performed. In 101 cases (93%) there was no clinical sequelae following successful dural tear repair. There were statistical improvements (P < .05) in mJOA and NuC scores, but not NDI or SF36 scores. No specific baseline or operative factors were found to be associated with the occurrence of dural tears. In most cases, no further postoperative treatments of the dural tear were required, while there were 13 patients (12%) that required subsequent treatment of cerebrospinal fluid drainage. Analysis of those requiring further treatments did not identify an optimum treatment strategy for cervical dural tears. CONCLUSIONS: In this multicenter study, we report our findings on the largest reported series (n = 109) of cervical dural tears. In a vast majority of cases, no subsequent interventions were required and no clinical sequelae were observed.

C5 Palsy After Cervical Spine Surgery: A Multicenter Retrospective Review of 59 Cases.

STUDY DESIGN: A multicenter, retrospective review of C5 palsy after cervical spine surgery. OBJECTIVE: Postoperative C5 palsy is a known complication of cervical decompressive spinal surgery. The goal of this study was to review the incidence, patient characteristics, and outcome of C5 palsy in patients undergoing cervical spine surgery. METHODS: We conducted a multicenter, retrospective review of 13 946 patients across 21 centers who received cervical spine surgery (levels C2 to C7) between January 1, 2005, and December 31, 2011, inclusive. P values were calculated using 2-sample t test for continuous variables and χ2 tests or Fisher exact tests for categorical variables. RESULTS: Of the 13 946 cases reviewed, 59 patients experienced a postoperative C5 palsy. The incidence rate across the 21 sites ranged from 0% to 2.5%. At most recent follow-up, 32 patients reported complete resolution of symptoms (54.2%), 15 had symptoms resolve with residual effects (25.4%), 10 patients did not recover (17.0%), and 2 were lost to follow-up (3.4%). CONCLUSION: C5 palsy occurred in all surgical approaches and across a variety of diagnoses. The majority of patients had full recovery or recovery with residual effects. This study represents the largest series of North American patients reviewed to date.

Posterolateral Fusion Versus Interbody Fusion for Degenerative Spondylolisthesis: A Systematic Review and Meta-Analysis.

STUDY DESIGN: Systematic literature review and meta-analysis. OBJECTIVE: This study is a meta-analysis assessing the clinical outcomes of degenerative lumbar spondylolisthesis treated with either a posterolateral fusion (PLF) or interbody fusion (IBF) SUMMARY OF BACKGROUND DATA.: Degenerative spondylolisthesis remains one of the most common reasons for which lumbar fusion is performed in the United States. Both PLF and IBF have been advanced as adequate surgical techniques that result in successful fusion and improved clinical outcomes. METHODS: A systematic review of PubMed, Cochrane, and Embase was performed. The pooled results were performed by calculating the effect size based on the Hedges g standardized difference in means or odds ratio. Studies were weighted by the inverse of the variance. Heterogeneity was assessed using the Q statistic and I. Sensitivity analysis was performed through single elimination of studies. Publication bias was assessed by funnel plot assessment and the Egger-Harbord test. RESULTS: The systematic review resulted in 865 articles. After two-reviewer assessment, five articles were found to match all of the inclusion criteria and were included in the meta-analysis. The combined effect size was found to be in favor of PLF for length of stay (P = 0.002); however, there were no differences in fusion rate, operative time, Estimated blood loss, Oswestry Disability Index, Short Form 36, Visual Analog Scale, or complication rate between PLF and IBF. All of the variables demonstrated relative homogeneity, with I < 25. The sensitivity analysis validated the results of the model and there was no publication bias detected. CONCLUSION: Patients with degenerative spondylolisthesis can be effectively managed with either a PLF or IBF with no significant differences in clinical outcomes or fusion rate between the two groups. Length of stay was the only variable that was found to be in favor of either group, with the PLF group demonstrating a shortened hospitalization. LEVEL OF EVIDENCE: 3.

Open Versus Minimally Invasive Fixation Techniques for Thoracolumbar Trauma: A Meta-Analysis.

Study Design Systematic literature review and meta-analysis of studies published in English. Objective This study evaluated differences in outcome variables between percutaneous and open pedicle screws for traumatic thoracolumbar fractures. Methods A systematic review of PubMed, Cochrane, and Embase was performed. The variables of interest included postoperative visual analog scale (VAS) pain score, kyphosis angle, and vertebral body height, as well as intraoperative blood loss and operative time. The results were pooled by calculating the effect size based on the standardized difference in means. The studies were weighted by the inverse of the variance, which included both within- and between-study error. Confidence intervals were reported at 95%. Heterogeneity was assessed using the Q statistic and I (2). Results After two-reviewer assessment, 38 studies were eliminated. Six studies were found to meet inclusion criteria and were included in the meta-analysis. The combined effect size was found to be in favor of percutaneous fixation for blood loss and operative time (p < 0.05); however, there were no differences in vertebral body height (VBH), kyphosis angle, or VAS scores between open and percutaneous fixation. All of the studies demonstrated relative homogeneity, with I (2) < 25. Conclusions Patients with thoracolumbar fractures can be effectively managed with percutaneous or open pedicle screw placement. There are no differences in VBH, kyphosis angle, or VAS between the two groups. Blood loss and operative time were decreased in the percutaneous group, which may represent a potential benefit, particularly in the polytraumatized patient. All variables in this study demonstrated near-perfect homogeneity, and the effect is likely close to the true effect.

A Meta-Analysis of the Clinical and Fusion Results following Treatment of Symptomatic Cervical Pseudarthrosis.

Study Design Systematic literature review and meta-analysis. Objective This study is a meta-analysis assessing the fusion rate and the clinical outcomes of cervical pseudarthrosis treated with either a posterior or a revision anterior approach. Methods A literature search of PubMed, Cochrane, and Embase was performed. Variables of interest included fusion rate and clinical success. The effect size based on logit event rate was calculated from the pooled results. The studies were weighted by the inverse of the variance, which included both within- and between-study error. The confidence intervals were reported at 95%. Heterogeneity was assessed using the Q statistic and I (2), where I (2) is the estimate of the percentage of error due to between-study variation. Results Sixteen studies reported fusion outcomes; 10 studies reported anterior and/or posterior results. The pooled fusion success was 86.4% in the anterior group and 97.1% in the posterior group (p = 0.028). The anterior group demonstrated significant heterogeneity with Q value of 34.2 and I (2) value of 73.7%; no heterogeneity was seen in the posterior group. The clinical outcomes were reported in 10 studies, with eight reporting results of anterior and posterior approaches. The pooled clinical success rate was 77.0% for anterior and 71.7% for posterior (p = 0.55) approaches. There was significant heterogeneity in both groups (I (2) 16.1; 19.2). Conclusions Symptomatic cervical pseudarthrosis can be effectively managed with either an anterior or a posterior approach. The posterior approach demonstrates a significantly greater fusion rate compared with the anterior approach, though the clinical outcome does not differ between the two groups.

A meta-analysis of cervical foraminotomy: open versus minimally-invasive techniques.

BACKGROUND CONTEXT: The posterior cervical foraminotomy (PCF) may be performed using an open or minimally-invasive (MIS) approach using a tubular retractor. Although there are theoretical advantages such as less blood loss and shorter hospitalizations, there is no consensus in the literature regarding the best approach for treatment. PURPOSE: To assess clinical outcomes of PCF treated with either an open or an MIS approach using a tubular retractor. STUDY DESIGN: Systematic literature review and meta-analysis of English language studies for the treatment of cervical radiculopathy treated with foraminotomy. PATIENT SAMPLE: Pooled patient results from Level I studies and Level IV retrospective studies. OUTCOME MEASURES: Meta-analysis for clinical success as determined by Odom and Prolo criteria, and visual analog scale scores for arm and neck pain. METHODS: A literature search of three databases was performed to identify investigations performed in the treatment of PCF with an open or MIS approach. The pooled results were performed by calculating the effect size based on the logit event rate. Studies were weighted by the inverse of the variance, which included both within and between-study errors. Confidence intervals (CIs) were reported at 95%. Heterogeneity was assessed using the Q statistic and I-squared, where I-squared is the estimate of the percentage of error due to between-study variation. RESULTS: The initial literature search resulted in 195 articles, of which, 20 were determined as relevant on abstract review. An open foraminotomy approach was performed in six; similarly, an MIS approach was performed in three studies. The pooled clinical success rate was 92.7% (CI: 88.9, 95.3) for open foraminotomy and 94.9% (CI: 90.5, 97.4) for MIS foraminotomy, which was not statistically significant (p=.418). The open group demonstrated relative homogeneity with Q value of 7.6 and I(2) value of 34.3%; similarly, the MIS group demonstrated moderate study heterogeneity with Q value of 4.44 and I(2) value of 54.94%. CONCLUSIONS: Patients with symptomatic cervical radiculopathy from foraminal stenosis can be effectively managed with either a traditional open or an MIS foraminotomy. There is no significant difference in the pooled outcomes between the two groups.

Three-dimensional Intraoperative Imaging Modalities in Orthopaedic Surgery: A Narrative Review.

Intraoperative imaging and navigation systems have revolutionized orthopaedic surgery for the spine, joints, and orthopaedic trauma. Imaging modalities such as the isocentric C-arm, O-arm imaging, and intraoperative MRI or navigation systems allow the visualization of surgical instruments and implants relative to a three-dimensional CT image or MRI. Studies show that these technologies lower the rates of implant misplacement and inadequate fracture reduction, thereby improving surgical outcomes and reducing reoperation rates. An additional benefit is reduced radiation exposure compared with that for conventional fluoroscopy. Concerns surrounding adoption of these technologies include cost and increased operating times, but improvements in design and protocol may improve the integration of these imaging modalities into the operating room.

The 5-year cost-effectiveness of anterior cervical discectomy and fusion and cervical disc replacement: a Markov analysis.

STUDY DESIGN: A Markov state-transition model was developed to evaluate the cost-effectiveness of anterior cervical discectomy and fusion (ACDF) and cervical disc replacement (CDR) at 5 years. OBJECTIVE: To determine the cost-effectiveness of ACDF and CDR at 5 years. SUMMARY OF BACKGROUND DATA: ACDF and CDR are surgical options for the treatment of an acute cervical disc herniation with associated myelopathy/radiculopathy. Cost-effectiveness analysis provides valuable information regarding which intervention will lead to a more efficient utilization of health care resources. METHODS: Outcome and complication probabilities were obtained from existing literature. Physician costs were based on a fixed percentage of 140% of 2010 Medicare reimbursement. Hospital costs were determined from the Nationwide Inpatient Sample. Utilities were derived from responses to health state surveys (Short Form 36) at baseline and at 5 years from the treatment arms of the ProDisc-C trial. Incremental cost-effectiveness ratios were used to compare treatments. One-way sensitivity analyses were performed on all parameters within the model. RESULTS: CDR generated a total 5-year cost of $102,274, whereas ACDF resulted in a 5-year cost of $119,814. CDR resulted in a generation of 2.84 quality-adjusted life years, whereas ACDF resulted in 2.81. The incremental cost-effectiveness ratio was -$557,849 per quality-adjusted life year gained. CDR remained the dominant strategy below a cost of $20,486. ACDF was found to be a cost-effective strategy below a cost of $18,607. CDR was the dominant strategy when the utility value was above 0.713. CDR remained the dominant strategy assuming an annual complication rate less than 4.37%. CONCLUSION: ACDF and CDR were both shown to be cost-effective strategies at 5 years. CDR was found to be the dominant treatment strategy in our model. Further long-term studies evaluating the clinical and quality-of-life outcomes of these 2 treatments are needed to further validate the model. LEVEL OF EVIDENCE: 5.

National trends in outpatient surgical treatment of degenerative cervical spine disease.

Study Design Retrospective population-based observational study. Objective To assess the growth of cervical spine surgery performed in an outpatient setting. Methods A retrospective study was conducted using the United States Healthcare Cost and Utilization Project's State Inpatient and Ambulatory Surgery Databases for California, New York, Florida, and Maryland from 2005 to 2009. Current Procedural Terminology, fourth revision (CPT-4) and International Classification of Diseases, ninth revision Clinical Modification (ICD-9-CM) codes were used to identify operations for degenerative cervical spine diseases in adults (age > 20 years). Disposition and complication rates were examined. Results There was an increase in cervical spine surgeries performed in an ambulatory setting during the study period. Anterior cervical diskectomy and fusion accounted for 68% of outpatient procedures; posterior decompression made up 21%. Younger patients predominantly underwent anterior fusion procedures, and patients in the eighth and ninth decades of life had more posterior decompressions. Charlson comorbidity index and complication rates were substantially lower for ambulatory cases when compared with inpatients. The majority (>99%) of patients were discharged home following ambulatory surgery. Conclusions Recently, the number of cervical spine surgeries has increased in general, and more of these procedures are being performed in an ambulatory setting. The majority (>99%) of patients are discharged home but the nature of analyzing administrative data limits accurate assessment of postoperative complications and thus patient safety. This increase in outpatient cervical spine surgery necessitates further discussion of its safety.