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Background: A gap in the literature exists regarding the association between number of allergies and patient-reported outcomes measures (PROMs) for patients undergoing spine surgery., Methods: Consecutive cervical or lumbar spine surgery patients were identified from a prospective registry from April 2017 to July 2020. Patients were grouped into those with 0, 1, 2, or ≥3 allergies. Demographics were compared between the groups. PROMs included Neck Disability Index, Oswestry Disability Index, visual analog scale (VAS) neck pain, VAS arm pain, VAS back pain, VAS leg pain, short form 12 (SF-12) physical component score, SF-12 mental component score, and patient-reported outcomes measurement information system physical function (PROMIS-PF), and outcomes were compared between the groups through multivariable analysis at up to 1-year follow-up. Associations between number of allergies and achieving a minimal clinically important difference (MCID) in the 9 aforementioned PROMs at 1-year follow-up were assessed., Results: This study included 148 cervical and 517 lumbar patients. After controlling for demographic differences, a higher number of allergies was associated with less improvement in VAS neck pain, SF-12 physical component score, and PROMIS-PF at 12 weeks following cervical surgery and less improvement in PROMIS-PF at 2 weeks following lumbar surgery ( P < 0.05). However, these associations failed to persist after 6 months and 12 weeks following surgery in cervical and lumbar patients, respectively ( P > 0.05). No association was identified between number of allergies and achievement of MCID in any of the 9 studied PROMs at 1-year follow-up., Conclusions: The higher number of allergies was associated with less improvement in PROMs in the early postoperative period but not at longer-term follow-up., Clinical Relevance: These findings provide data that can be utilized while counseling patients and setting postoperative expectations., Competing Interests: Declaration of Conflicting Interests : The authors report no conflicts of interest in this work., (This manuscript is generously published free of charge by ISASS, the International Society for the Advancement of Spine Surgery. Copyright © 2023 ISASS. To see more or order reprints or permissions, see http://ijssurgery.com.)

Background Context: Minimally invasive transforaminal lumbar interbody fusion (MI-TLIF) is a common operative approach to address degenerative lumbar stenosis and spondylolisthesis which has failed nonoperative care. Compared to open TLIF, MI-TLIF relies to a greater extent on indirect decompression resulting in a heightened awareness of spondylolisthesis reduction among MI surgeons. To what extent intraoperative reduction is achieved as well as the rate and clinical impact of loss or reduction and slip recurrence remain unknown., Purpose: To determine the rate and clinical impact of slip recurrence after MI-TLIF with expandable cage technology STUDY DESIGN/SETTING: Retrospective Cohort Study PATIENT SAMPLE: Patients undergoing MI-TLIF for degenerative spondylolisthesis using an articulating, expandable cage OUTCOME MEASURES: Patient-reported outcome measures (PROMs), including the Oswestry Disability Index (ODI), visual analog scale (VAS) for back/leg pain, Short Form-12 (SF-12), and PROMIS Physical Function (PF) METHODS: Patients undergoing MI-TLIF for degenerative spondylolisthesis using articulating, expandable cages from 2017 to 2019 were retrospectively studied. Lateral radiographs were reviewed and evaluated for the presence or absence of spondylolisthesis preoperatively, intraoperatively, and at follow-up times including 2 weeks, 6 weeks, 12 weeks, 6 months, and 1 year postoperatively. Spondylolisthesis was measured from the posterior inferior corner of the cephalad vertebra to the posterior superior corner of the caudal vertebra, with any measurement >1 mm classified as spondylolisthesis, and Meyerding grade was noted. Intraoperative reduction was measured, and loss of reduction was defined as >1 mm increase in spondylolisthesis comparing follow-up imaging to intraoperative films. PROMs were recorded at the preoperative and follow-up time points. Fusion was assessed at 1 year postoperatively via CT., Results: A total of 63 patients and 70 levels were included, with mean age 59.8 years (SD,13.8). 19 levels (27.1%) had complete reduction intraoperatively, 40 (57.1%) had partial reduction, and 11 (15.7%) had no reduction. Of the 30 levels with loss of reduction (50.8%), 20 (66.7%) occurred by 2 weeks postoperatively and 28 (93.3%) occurred by 12 weeks postoperatively. At 6 months, there were significant differences between those who had loss of reduction and those who did not in VAS back pain (3.0 vs. 0.9, p = .017) and SF-12 PCS (41.5 vs. 50.0, p = .035), but no differences were found between the groups for any instruments at any other time points. The overall fusion rate was 82.1% (32/39) at 1 year postoperatively. There was no significant difference in fusion rate between the loss of reduction (16/20) and no loss of reduction (20/23) groups. Patients with loss of reduction had no difference in reoperation rate (1/28) compared to those without loss of reduction (2/24)., Conclusions: While a majority of patients demonstrated reduction intraoperatively, 51% had loss of reduction, most commonly in the acute postoperative period. There were few differences in PROMs between patients who had loss of reduction and those who did not, suggesting that radiographic loss of reduction after MI-TLIF in the setting of degenerative spondylolisthesis may not be clinically meaningful., (Copyright © 2021 Elsevier Inc. All rights reserved.)

Study Design: Retrospective cohort study., Objective: To determine the rate of early failures (readmission or reoperation for new or recurrent pain/neurological symptoms) within 30 days after lumbar discectomy and identify associated risk factors., Methods: A retrospective cohort study was conducted of patients undergoing lumbar discectomy in the National Surgical Quality Improvement Program database between 2013 and 2017. Rates of readmission for new or recurrent symptoms or reoperation for revision discectomy or fusion within 30 days postoperatively were measured and correlated with risk factors., Results: In total 62 690 patients were identified; overall rate of readmission within 30 days was 3.3%, including 1.2% for pain or neurological symptoms. Populations at increased risk of readmission were those with 3 or more levels of treatment (2.0%, odds ratio [OR] 2.8%, P < .01), age >70 years (1.8%, OR 1.6, P < .01), class 3 obesity (1.5%, OR 1.4, P = .04), and female gender (1.4%, OR 1.2, P = .02). The overall rate of reoperation within 30 days was 2.2%, including 1.2% for revision decompression or lumbar fusion surgery. Populations at increased risk of reoperation were revision discectomies (1.4%, OR 1.7, P < .01) and females (1.1%, OR 1.4, P < 0.01). Extraforaminal discectomies were associated with lower rates of readmission (0.7%, OR 0.6, P = 0.02) and reoperation (0.4%, OR 0.4, P = .01)., Conclusions: Early failures after lumbar discectomy surgery are rare. However, certain subpopulations are associated with increased rates of early failure: obesity, multilevel surgery, females, and revision discectomies.

Study Design: A retrospective cohort study., Objective: The aim of this study was to identify an association between preoperative opioid use and reoperations rates., Summary of Background Data: Chronic opioid use is a public health crisis in the United States and has been linked to worse outcomes after lumbar spine surgery. However, no studies have identified an association between preoperative opioid use and reoperations rates., Methods: A retrospective cohort study was conducted using patients from one private insurance database who underwent primary lumbar decompression/discectomy (LDD) or posterior/transforaminal lumbar interbody fusion (PLIF/TLIF). Preoperative use of five specific opioid medications (tramadol, hydromorphone, oxycodone, hydromorphone, and extended-release oxycodone) was categorized as acute (within 3 months), subacute (acute use and use between 3 and 6 months), or chronic (subacute use and use before 6 months). Multivariate regression, controlling for multilevel surgery, age, sex, and Charlson Comorbidity Index, was used to determine the association of each medication on reoperations within 5 years., Results: A total of 11,551 patients undergoing LDD and 3291 patients undergoing PLIF/TLIF without previous lumbar spine surgery were identified. In the LDD group, opioid-naïve patients had a 5-year reoperation rate of 2.8%, compared with 25.0% and 8.0 with chronic preoperative use of hydromorphone and oxycodone, respectively. In multivariate analysis, any preoperative use of oxycodone was associated with increased reoperations (odds ratios [OR] = 1.4, 2.0, and 2.3, for acute, subacute, and chronic use; P < 0.01). Chronic use of hydromorphone was also associated with increased reoperations (OR = 7.5, P < 0.01).In the PLIF/TLIF group, opioid-naïve patients had a 5-year reoperation rate of 11.3%, compared with 66.7% and 16.8% with chronic preoperative use of hydromorphone and oxycodone, respectively. In multivariate analysis, any preoperative use of hydromorphone was associated with increased reoperations (OR = 2.9, 4.0, and 14.0, for acute, subacute, and chronic use; P < 0.05)., Conclusion: Preoperative use of the higher-potency opioid medications is associated with increased reoperations after LDD and PLIF/TLIF in a dose-dependent manner. Surgeons should use this data for preoperative opioid cessation counseling and individualized risk stratification.Level of Evidence: 3., (Copyright © 2020 Wolters Kluwer Health, Inc. All rights reserved.)

Background: Lateral lumbar interbody fusion (LLIF) is used to treat multiple conditions, including spondylolisthesis, degenerative disc disorders, adjacent segment disease, and degenerative scoliosis. Although many advocate for posterior fixation with LLIF, stand-alone LLIF is increasingly being performed. Yet the fusion rate for stand-alone LLIF is unknown., Purpose: Determine the fusion rate for stand-alone LLIF., Study Design: Systematic review., Methods: We queried Cochrane, EMBASE, and MEDLINE for literature on stand-alone LLIF fusion rate with a publication cutoff of April 2020. LLIF surgery was considered stand-alone when not paired with supplemental posterior fixation. Cohort fusion rate differences were calculated and tested for significance (p<0.05). All reported means were pooled., Results: A total of 2,735 publications were assessed. Twenty-two studies met inclusion criteria, including 736 patients and 1,103 vertebral levels. Mean age was 61.7 years with BMI 26.5 kg/m 2 . Mean fusion rate was 85.6% (range, 53.0%-100.0%), which did not differ significantly by number of levels fused (1-level, 2-level, and ≥3-level). Use of rhBMP-2 was reported in 39.3% of subjects, with no difference in fusion rates between studies using rhBMP-2 (87.7%) and those in which rhBMP-2 was not used (83.9%, odds ratio=1.37, p=0.448). Fusion rate did not differ with the addition of a lateral plate, or by underlying diagnosis. All-complication rate was 42.2% and mean reoperation rate was 11.1%, with 2.3% reoperation due to pseudarthrosis. Of the studies comparing stand-alone to circumferential fusion, pooled fusion rate was found to be 80.4% versus 91.0% (p=0.637)., Conclusions: Stand-alone LLIF yields high fusion rates overall. The wide range of reported fusion rates and lower fusion rates in studies involving subsequent surgical reoperation highlights the importance of proper training in this technique and employing a rigorous algorithm when indicating patients for stand-alone LLIF. Future research should focus on examining risk factors and patient-reported outcomes in stand-alone LLIF., (Copyright © 2020 Elsevier Inc. All rights reserved.)

Study Design: Follow-up study., Objective: To determine whether minimally invasive lumbar spine surgery outcomes are different between those who are lost to follow-up and those who are not., Summary of Background Data: Lost to follow-up patients are a common source of selection bias for clinical outcomes research. Currently, there are no US based studies that evaluate the differences in outcomes of lost to follow-up patients after spine surgeries., Methods: A retrospective review of prospectively collected data of 289 patients who underwent minimally invasive lumbar surgery and were at least 1 year postsurgery was performed. Patients were divided into two groups: (1) lost to follow-up (LTF), defined as patients who had missed more than two consecutive follow-up visits and had not attended their 1-year follow-up appointment; and (2) not lost to follow-up. For the not-LTF cohort, patient response outcome measures (PROMs) (oswestry disability index (ODI), visual analog scale (VAS) back/leg, Short Form-12 (SF-12) Physical/Mental, PROMIS) and return to activities data were collected prospectively at each follow-up. For LTF patients, data were collected through emailed surveys or telephone interviews. PROMs and return to activities data of the two groups were compared. Sub-group analysis by type of surgery (decompression or fusion) was also performed., Results: For the entire cohort, independent t test analysis showed LTF patients had greater improvement in PROMIS Physical Function scores than those who were not-LTF (15.08 vs. 10.38, P = 0.026). For fusion surgeries, LTF patients showed a greater improvement in ODI (-30.94 vs. -16.23, P = 0.003) VAS back (-4.92 vs. -2.99, P = 0.044), and PROMIS-PF (16.09 vs. 10.38, P = 0.049). There were no significant differences in complication rates between LTF and not LTF patients., Conclusion: Patients undergoing minimally invasive lumbar surgery-in particular lumbar fusions-who are lost to follow-up and responded to subsequent email and phone interviews showed greater improvements in self-reported outcomes than those who continued to follow-up. Thus, our results suggest that a substantial subset of patients who are lost to follow-up do not fare worse than those who do follow-up. However, an opposite response cannot be excluded in those who did not respond to email and phone interviews., Level of Evidence: 3.

Purpose: To determine the rate of preoperative modifiable laboratory abnormalities (both major and minor) and the association with early postoperative medical and surgical complications., Methods: All patients undergoing thoracolumbar three-column osteotomy between 2013 and 2016 with preoperative laboratory data were identified. Potential preoperative modifiable laboratory abnormalities (major and minor) were assessed including hyponatremia (sodium < 130 and < 135 mEq/L), anemia (hematocrit < 25% and < 30%), renal insufficiency (creatinine ≥ 1.8 and ≥ 1.2 mg/dL), coagulopathy (INR ≥ 1.8 and ≥ 1.2), and hypoalbuminemia (albumin < 2.5 and < 3.5 g/dL). Multivariate logistic regression was used to determine associations with 30-day complications after controlling for possible confounding factors., Results: A total of 195 patients were identified. The rates of major and minor preoperative laboratory abnormalities were 7.7% and 31.3%, respectively. The rates of serious medical, minor medical, and surgical complications over 30-days were 6.7%, 21.5%, and 10.3%, respectively. In multivariate analysis the presence of major preoperative laboratory abnormalities had a significant association with serious medical complications (odds ratio [OR] 77.8, P < 0.001), and minor medical complications (OR 13.3, P < 0.001), but not surgical complications (P = 0.243). The presence of minor preoperative laboratory abnormalities had a significant association with serious medical complications (OR 10.4, P = 0.041) and minor medical complications (OR 2.4, P = 0.045), but not surgical complications (P = 0.490)., Conclusions: While major laboratory abnormalities had a strong association with complications, even minor modifiable laboratory abnormalities had a significant association with both serious and minor medical complications.

Study Design: Systematic review., Objectives: The purpose of the current study is to determine the overall incidence of Heterotopic Ossification (HO) following cervical disc arthroplasty (CDA) as well as per annum rates., Summary of Background Data: CDA is a well-established surgical modality for treatment of one- and two-level degenerative disc disease that has failed conservative treatment. Despite its proven mid-term clinical success, the potential for accelerated HO following CDA remains an area of clinical concern., Methods: A MEDLINE literature search was performed using PubMed, the Cochrane Database of Systematic Reviews, and Embase from January 1980 to February 2018. We included studies involving adult patients, who underwent CDA, documentation of HO, with >12 month follow-up. The pooled results were obtained by calculating the effect size based on the logit event rate. Per annum rates were determined based on weighted averages according to average follow-up period., Results: The initial database review resulted in 230 articles, with 19 articles that met inclusion and exclusion criteria. These pooled results included 2151-disc levels and 1732 patients (50% men and 50% women) who underwent CDA and were evaluated for postoperative HO. The mean age was 45 years with a mean follow-up of 60 months. Sixteen studies reported the occurrence of severe HO resulting in 22.8% of disc levels developing severe HO. When stratifying these studies based on funding type, severe HO was reported at a rate of 21.6% by IDE studies and 27.9% by independent studies., Conclusion: The findings of the pooled data show the incidence of severe HO following CDA to be 22.8%. However, there is a significant difference in reported rates of mild and severe HO between IDE and independent data. This alludes to possible underreporting of HO and severity of HO in the industry sponsored IDE studies when compared with independent studies., Level of Evidence: 2.

Introduction: Although the Patient-reported Outcomes Measurement Information System (PROMIS) is increasingly being used, there are few studies assessing the psychometric properties of PROMIS in minimally invasive spine (MIS) surgery. Thus, the purpose of this study was to perform a psychometric evaluation of PROMIS Physical Function Computer Adaptive Testing (PROMIS-PF CAT) in MIS lumbar surgery., Methods: The patient-reported outcome measures collected preoperatively and postoperatively of patients undergoing MIS lumbar surgery were retrospectively analyzed to assess responsiveness, coverage, discriminant validity, and concurrent validity of PROMIS-PF CAT., Results: Four hundred twenty-one patients were included. The responsiveness of PROMIS Physical Function (PROMIS-PF) was lower than that of the Oswestry Disability Index (ODI) in the decompression subgroup. Although the ODI had a ceiling effect of 16.7% at 1 year, the Short-Form 12 physical health score and PROMIS-PF did not show floor or ceiling effects. PROMIS-PF demonstrated discriminant validity preoperatively and postoperatively and convergent validity with the ODI, as evidenced by a significant strong negative correlation but not with the Short-Form 12 Physical Health Score, as evidenced by the variability in strength of correlation., Conclusions: Although the PROMIS-PF showed lower responsiveness than the ODI, particularly in the decompression subgroup, it demonstrated discriminant validity preoperatively and postoperatively, convergent validity with ODI, and better coverage than ODI. These findings suggest that the PROMIS-PF CAT demonstrates reasonable psychometric properties and may be a good surrogate for the ODI.

Objective: In an effort to prevent loss of segmental lordosis (SL) with minimally invasive interbody fusions, manufacturers have increased the amount of lordosis that is built into interbody cages. However, the relationship between cage lordotic angle and actual SL achieved intraoperatively remains unclear. The purpose of this study was to determine if the lordotic angle manufactured into an interbody cage impacts the change in SL during minimally invasive surgery (MIS) for lumbar interbody fusion (LIF) done for degenerative pathology., Methods: The authors performed a retrospective review of a single-surgeon database of adult patients who underwent primary LIF between April 2017 and December 2018. Procedures were performed for 1-2-level lumbar degenerative disease using contemporary MIS techniques, including transforaminal LIF (TLIF), lateral LIF (LLIF), and anterior LIF (ALIF). Surgical levels were classified on lateral radiographs based on the cage lordotic angle (6°-8°, 10°-12°, and 15°-20°) and the position of the cage in the disc space (anterior vs posterior). Change in SL was the primary outcome of interest. Subgroup analyses of the cage lordotic angle within each surgical approach were also conducted., Results: A total of 116 surgical levels in 98 patients were included. Surgical approaches included TLIF (56.1%), LLIF (32.7%), and ALIF (11.2%). There were no differences in SL gained by cage lordotic angle (2.7° SL gain with 6°-8° cages, 1.6° with 10°-12° cages, and 3.4° with 15°-20° cages, p = 0.581). Subgroup analysis of LLIF showed increased SL with 15° cages only (p = 0.002). The change in SL was highest after ALIF (average increase 9.8° in SL vs 1.8° in TLIF vs 1.8° in LLIF, p < 0.001). Anterior position of the cage in the disc space was also associated with a significantly greater gain in SL (4.2° vs -0.3°, p = 0.001), and was the only factor independently correlated with SL gain (p = 0.016)., Conclusions: Compared with cage lordotic angle, cage position and approach play larger roles in the generation of SL in 1-2-level MIS for lumbar degenerative disease.

Study Design: Retrospective cohort., Objective: To describe our technique for and evaluate the time demand, radiation exposure and outcomes of skin-anchored intraoperative three-dimensional navigation (ION) in minimally invasive (MIS) lumbar surgery, and to compare these parameters to 2D fluoroscopy for MI-TLIF., Summary of Background Data: Limited visualization of anatomic landmarks and narrow access corridor in MIS procedures result in greater reliance on image guidance. Although two-dimensional fluoroscopy has historically been used, ION is gaining traction., Methods: Patients who underwent MIS lumbar microdiscectomy, laminectomy, or MI-TLIF using skin-anchored ION and MI-TLIF by the same surgeon using 2D fluoroscopy were selected. Operative variables, radiation exposure, and short-term outcomes of all procedures were summarized. Time-demand and radiation exposure of fluoroscopy and ION for MI-TLIF were compared., Results: Of the 326 patients included, 232 were in the ION cohort (92 microdiscectomies, 65 laminectomies, and 75 MI-TLIFs) and 94 in the MI-TLIF using 2D fluoroscopy cohort. Time for ION setup and image acquisition was a median of 22 to 24 minutes. Total fluoroscopy time was a median of 10 seconds for microdiscectomy, 9 for laminectomy, and 26 for MI-TLIF. Radiation dose was a median of 15.2 mGy for microdiscectomy, 16.6 for laminectomy, and 44.6 for MI-TLIF, of this, 93%, 95%, and 37% for microdiscectomy, laminectomy, and MI-TLIF, respectively were for ION image acquisition, with the rest attributable to the procedure. There were no wrong-level surgeries. Compared with fluoroscopy, ION for MI-TLIF resulted in lower operative times (92 vs. 108 min, P < 0.0001), fluoroscopy time (26 vs. 144 s, P < 0.0001), and radiation dose (44.6 vs. 63.1 mGy, P = 0.002), with equivalent time-demand and length of stay. ION lowered the radiation dose by 29% for patients and 55% for operating room personnel., Conclusion: Skin-anchored ION does not increase time-demand compared with fluoroscopy, is feasible, safe and accurate, and results in low radiation exposure., Level of Evidence: 3.

Due to the high societal and financial burden of spinal disorders, spine surgery is thought to be one of the most impactful targets for healthcare cost reduction. One avenue for cost-reduction that is increasingly being explored not just in spine surgery but across specialties is the performance of surgeries in ambulatory surgery centers (ASCs). Despite potential cost-savings, the utilization of ASCs for spine surgery remains largely limited to high-volume centers in the US, and predominantly for single- or two-level lumbar microdiscectomy and anterior cervical discectomy and fusion (ACDF) procedures. Factors most commonly cited for the lack of wider adoption include the risk of life-threatening complications, paucity of guidelines, and limited accessibility of these procedures to various patient populations. Thus, the future growth and adoption of ambulatory spine surgery depends on addressing these concerns by developing evidence-based guidelines for patient- and procedure selection, creating risk-stratification tools, devising appropriate discharge recommendations, and optimizing care protocols to ensure that safety, efficacy and outcomes are maintained. Other avenues that may allow for more widespread use of ASCs include the use of electronic health tools for post-operative monitoring after discharge from the ASC, increasing accessibility of ambulatory procedures to eligible populations, and identifying systemic inefficiencies and implementing process-improvement measures to optimize patient-selection, scheduling and peri-operative management. The success of ambulatory surgery ultimately depends not only on the surgical procedure, but also on its organization upstream and downstream. It provides an exciting and burgeoning avenue for innovation, cost-reduction and value-creation., Competing Interests: Conflicts of Interest: Dr. Steven J. McAnany: Currently receiving Consulting Fees from Titan, Nuvasive, Stryker K2M. AS Vaishnav has no conflicts of interest to declare., (2019 Journal of Spine Surgery. All rights reserved.)

Objective: The aim of this study was to compare the patient-reported outcome measures Neck Disability Index (NDI) and visual analog scale (VAS) with the Patient Reported Outcomes Measurement Information System (PROMIS) physical function (PF) and pain interference (PI) measures, respectively, and to determine their correlations in a surgical population longitudinally.Legacy outcome measures such as NDI and VAS are essential for analyzing treatments in spine surgery for cervical disc herniations with radiculopathy. Despite their usefulness, administrative burdens impose limits on completion of these measures. PROMIS was developed as a patient outcome measure in order to improve reporting of patient symptoms and function and to reduce administrative burden. Despite early positive results of PROMIS in orthopedics, NDI and VAS scores have not been compared with PROMIS scores in patients with cervical disc herniations with radiculopathy., Methods: Eighty patients undergoing surgery for cervical disc herniations with radiculopathy were included. All patients were treated at the same tertiary spine center. Patients were seen and PROMIS PF and PI, NDI, and VAS arm and neck pain scores were collected preoperatively and at 1 year postoperatively. Correlations between NDI, VAS, and PROMIS PF and PI were quantified using Pearson correlation coefficients. Two-tailed Student t-tests were used to demonstrate correlation significance, with alpha = 0.05., Results: All 80 (100%) patients completed all preoperative questionnaires. Fifty-seven (72%) and 75 (94%) patients completed all questionnaires at baseline and at the 6-month and 1-year follow-ups, respectively. PROMIS PF and NDI scores demonstrated a strong negative correlation, with Pearson r values of -0.81, -0.77, and -0.75 at baseline, 6 months, and 1 year. PROMIS PI and VAS neck pain scores demonstrated a moderately positive correlation, with Pearson r values of 0.51, 0.61, and 0.6. PROMIS PI and VAS arm pain scores demonstrated a moderately positive correlation, with Pearson r values of 0.46, 0.47, and 0.45., Conclusions: PROMIS PF scores have a strong negative correlation with NDI scores at baseline and in the postoperative course in patients undergoing surgery for cervical disc herniations with radiculopathy. PROMIS PI scores have a moderately positive correlation with VAS neck and arm pain scores at baseline and in the postoperative course. Surgeons may factor these correlation results into the interpretation of patient-reported outcome measures in patients with cervical radiculopathy. Use of PROMIS PF and PI for this patient population may reduce administrative burden while providing reliable outcomes data.

Background: Anterior lumbar interbody fusion (ALIF) has been used for treatment of a variety of spinal conditions including degenerative disc disorders and low-grade spondylolisthesis. Expected fusion rate of stand-alone ALIF constructs is currently unclear. The aim of this study was to examine the fusion rate for ALIF without supplemental posterior fusion or instrumentation (stand-alone ALIF)., Methods: We queried the MEDLINE, COCHRANE, and EMBASE databases for all literature related to spine fusion rates using a stand-alone ALIF procedure with a publication cutoff date of July 19, 2018. Supplementary combinations of search terms included spine, fusion, fixation, rate(s), and arthrodesis. ALIF surgery was considered stand-alone when not paired with supplemental posterior fusion or posterior spinal instrumentation. Nonhuman and non-English publications were excluded. Cohort fusion rate differences were calculated using Student t test with significance assigned if p value was less than .05., Results: Title and abstract level review required assessing 840 unique publications. Across the 55 studies that met the inclusion criteria of this systematic review, 5,517 patients and 6,303 vertebral levels were fused. The overall weighted average patient fusion rate following stand-alone ALIF was 88.2% (range: 16.6%-100%). In the 31 studies with at least 50 subjects, the weighted average fusion rate following stand-alone ALIF was 88.6% (range: 57.5%-99.0%). Use of anterior fixation plate devices yielded a fusion rate of 94.2%. Newer zero-profile interbody implants had a fusion rate of 89.2%. Fusion rates were lower in studies with 50% or more subjects having positive smoking and worker's compensation status, however these results were found to be statistically insignificant (p>.05). Fusion rate for subjects in the eight rhBMP-2 study groups was 94.4% (n=889) compared with 84.8% (n=3,102) in 38 study groups without rhBMP-2 used., Conclusions: Based on the available data, stand-alone ALIF procedures yield high fusion rates overall. Fusion failure and pseudoarthrosis rates are higher in study populations involving a high percentage of smokers or positive workers compensation status. Allograft utilization does not significantly improve fusion rate when compared with autograft in stand-alone ALIF constructs., (Copyright © 2019 Elsevier Inc. All rights reserved.)

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., (Copyright © 2018 Elsevier Inc. All rights reserved.)

Study Design: This was a retrospective cohort study., Objectives: The main objectives of this study were to identify epidemiological trends, differences, and complications in patients undergoing surgical treatment for single-level cervical radiculopathy (SLCR)., Summary of Background Data: SLCR that fails nonoperative management is effectively treated with either anterior cervical discectomy and fusion (ACDF), cervical disc replacement (CDR), or posterior cervical foraminotomy (PCF). Although studies have shown that all 3 options are clinically effective, trends in usage, differences in patient population, and differences in complications remain unknown., Materials and Methods: Patients who underwent either ACDF, CDR, or PCF in the treatment of SLCR from 2010 to 2016 were retrospectively reviewed using the National Surgical Quality Improvement Program (NSQIP) database. Demographic data consisted of sex, age, ASA class, body mass index, and inpatient/outpatient status. Complications included surgical site infection, pneumonia, reintubation, pulmonary embolism, deep vein thrombosis, readmissions, reoperations, operating time, and hospital length of stay. Utilization trends by year among the 3 procedures were also analyzed., Results: A total of 1102 patients with SLCR treated with single-level ACDF, CDR, or PCF were identified in NSQIP from 2010 to 2016. There was a relative increase in the number of CDR procedures (7.7%-16.1%) and a corresponding decrease in PCF procedures (20.3%-10.6%) without a significant effect on ACDF procedures (72.0%-73.3%). Patients who underwent CDR were younger and in a lower ASA class than those undergoing ACDF or PCF. Patients undergoing PCF were more likely to be treated as an outpatient. PCF procedures also had the shortest operating time and hospital length of stay. There were no significant differences in complications among the 3 procedures. Moreover, there were no significant trends in demographics or outcome measures., Conclusions: ACDF remains the most common surgical treatment for patients with SLCR, and its utilization has remained consistent. Meanwhile, the increased utilization of CDR for the treatment of SLCR has resulted in a corresponding decrease in the utilization of PCF.

Conditions of the spine are one of the most prevalent causes of global disability, and result in a considerable portion of total health expenditures. Surgical treatment of the spine has been demonstrated in multiple studies to be a cost-effective treatment option for many patients, especially with continuing improvements in surgical technique and instrumentation. Minimally invasive spine surgery (MISS), in particular, has evolved as a valuable option in treating certain patients. Numerous studies have analyzed minimally invasive techniques in regards to cost-effectiveness and other purported advantages. These advantages include conduciveness to outpatient settings, better perioperative and immediate post-operative benefits, and faster time to recovery. This article will describe the current literature on the advantages of MISS, specifically in regards to value and cost savings., Competing Interests: Conflicts of Interest: S Qureshi: Currently receiving consulting fees from Zimmer-Biomet, Stryker Spine, Globus Medical, Inc., K2M, OnPoint Surgical, Inc., Paradigm Spine; shareholder interest in Avaz Surgical, Vital 5; and royalties from RTI, Zimmer-Biomet, Stryker Spine; board membership at Healthgrades, Minimally Invasive Spine Study Group. SJ McAnany: Currently receiving consulting fees from Nuvasive, Titan. The other authors have no conflicts of interest to declare.

Background: Several fusion adjuncts exist to enhance fusion rates during minimally invasive transforaminal lumbar interbody fusion (MI-TLIF). The objective of this study was to compare fusion rates in patients undergoing MI-TLIF with either rhBMP-2 or cellularized bone matrix (CBM)., Methods: We conducted a single surgeon retrospective cohort study of patients who underwent MI-TLIF with either rhBMP-2 or CBM placed in an interbody cage. Single and multilevel procedures were included. Fusion was assessed on computed tomography scans at 12-month follow-up by an independent, blinded, board-certified neuroradiologist. Fusion rates and rate of revision surgery were compared with a Fisher exact test between the 2 groups. A multivariate regression analysis was performed to identify patient factors that were predictive of radiographic nonunion after MI-TLIF., Results: A total of 93 fusion levels in 78 patients were reviewed. Thirty-nine patients received CBM, and 39 patients received rhBMP-2. The patients receiving rhBMP-2 were older on average (61.4 vs 55.6, P = .03). The overall fusion rate was 68% in the CBM group (32/47 levels) and 78% in the rhBMP-2 group (36/46) ( P = .35). Only preoperative hypertension was predictive of radiographic nonunion (odds ratio = 3.5, P = .05). There were 3 smokers in the CBM group and 4 smokers in the BMP group, and 1 in each group experienced radiographic pseudarthrosis. A total of 4 patients, 3 in the CBM group and 1 in the BMP group ( P = .61), required revision for symptomatic pseudarthrosis. All of these patients had a single-level index procedure., Conclusions: There were no differences in radiographic fusion and rate of revision surgery in patients who underwent MI-TLIF with either rhBMP-2 or CBM as fusion adjuncts., Level of Evidence: 3., Clinical Relevance: Both rhBMP-2 and CBMs can be used as effective fusion adjuncts without any clear advantage of one over the other., Competing Interests: Disclosures and COI: An institutional review board approved this study. No funding was received to conduct this study. Sheeraz Qureshi is currently receiving grant/research support from the Cervical Spine Research Society; consulting fees from Zimmer-Biomet, Stryker Spine, Globus Medical, Inc.; and shareholder interest in Avaz Surgical and royalties from RTI, Zimmer-Biomet, Stryker Spine.

Background Context: Risk factors associated with rod fracture (RF) following adult spinal deformity (ASD) surgery fused to the sacrum remain debatable, and the impact of RF on patient-reported outcomes (PROs) after ASD surgery has not been investigated., Purpose: We aimed to evaluate the prevalence of and risk factors for RF and determine PROs changes associated with RF after ASD surgery fused to the sacrum., Study Design/setting: A retrospective single-center cohort study was performed., Patient Sample: Patients undergoing long-construct posterior spinal fusions to the sacrum performed at a single institution by two senior spine surgeons from 2004 to 2014 were included., Outcome Measures: Patient demographics, radiographic parameters, and surgical factors were assessed for risk factors associated with RF. Oswestry Disability Index (ODI) and Scoliosis Research Society-30 (SRS-30) scores were assessed at baseline, 1 year postoperatively, and latest follow-up., Methods: Inclusion criteria were ASD patients age >18 who had ≥5 vertebrae instrumented and fused posteriorly to the sacrum and either development of RF or no development of RF with minimum 2-year follow-up. Patient characteristics, operative data, radiographic parameters, and PROs were analyzed at baseline and follow-up. Separate Cox proportional hazard models based on rod material and diameter were used to determine factors associated with RF., Results: Five hundred twenty-six patients (80%) were available for analysis. RF occurred in 97 (18.4%) patients (unilateral RF n=61 [63%]; bilateral RF n=36 [37%]). Risk factors for fracture of 5.5 mm cobalt chromium (CC) instrumentation (CC 5.5 model) included preoperative sagittal vertical axis (hazard ratio [HR] 1.07, 95% confidence interval [95% CI] 1.02-1.14 per 1-cm increase), preoperative thoracolumbar kyphosis (HR 1.02, 95% CI 1.01-1.04 per 1-degree increase), and number of levels fused for patients who received rhBMP-2 <12 mg per level fused (HR 1.48, 95% CI 1.20-1.82 per 1-level increase). Implants that were 5.5-mm CC constructs were at a higher risk for fracture than 6.35-mm stainless steel (SS) constructs (HR 8.49, 95% CI 4.26-16.89). The RF group had less overall improvement in SRS Satisfaction (0.93 vs. 1.32; p=.007) and SRS Self-image domain scores (0.72 vs. 1.02; p=.01). The bilateral RF group had less overall improvement in ODI (8.1 vs. 15.8; p=.02), SRS Subscore (0.51 vs. 0.85; p=.03), and SRS Pain domain scores (0.48 vs. 0.95; p=.02) compared with the non-RF group at final follow-up., Conclusions: The prevalence of all RF after index procedures was 18.4%, 37% for bilateral RF. Greater preoperative sagittal vertical axis, greater preoperative thoracolumbar kyphosis, increased number of vertebrae fused for patients who received rhBMP-2 <12 mg per level fused, and CC 5.5-mm rod were associated with RF. Less improvement in patient satisfaction and self-image was noted in the RF group. Furthermore, bilateral RF significantly affected PROs as measured by ODI and SRS Subscore at final follow-up., (Copyright © 2018 Elsevier Inc. All rights reserved.)

Study Design: Cost-effectiveness analysis., Objective: To investigate 7-years cost-effectiveness of two-level cervical disc replacement (CDR) and anterior cervical discectomy and fusion (ACDF)., Summary of Background Data: CDR and ACDF are both effective treatment strategies for managing degenerative conditions of the cervical spine. CDR has been shown to be a more-cost effective intervention in the short term, but the long-term cost-effectiveness has not been established., Methods: We analyzed 7-years follow-up data from the two-level Medtronic Prestige LP investigational device exemption study. Short-form 36 (SF-36) data were converted into health utility scores using the SF-6D algorithm. Costs were based on direct costs from the payer perspective, and effectiveness was measured as quality-adjusted life years (QALYs). The willingness-to-pay (WTP) threshold was set to $50,000/QALY. A probabilistic sensitivity analysis was conducted via Monte Carlo simulation., Results: Two-level CDR had a 7-year cost of $176,654.19, generated 4.65 QALYs, and had a cost-effectiveness ratio of $37,993.53/QALY. Two-level ACDF had a 7-year cost of $158,373.48, generated 4.44 QALYs, and had a cost-effectiveness ratio of $35,635.72. CDR was associated with an incremental cost of $18,280.71 and an incremental effectiveness of 0.21 QALYs, resulting in an incremental cost-effectiveness ratio (ICER) of $89,021.04, above the WTP threshold. Our Monte Carlo simulation demonstrated CDR would be chosen 46% of the time based on 10,000 simulations., Conclusion: Two-level CDR and ACDF are both cost-effective procedures at 7-year follow up for treating degenerative conditions of the cervical spine. Based on an ICER of $89,021.04/QALY, we cannot conclude which treatment is the more cost-effective option at 7-years. CDR would be chosen 46% of the time based on 10,000 iterations of our Monte Carlo probabilistic sensitivity analysis., Level of Evidence: 3.

Study Design: Meta-analysis., Objectives: To assess return to play (RTP) rates in adolescent athletes with lumbar spondylolysis without spondylolisthesis treated conservatively or operatively., Methods: A review of Medline, EMBASE, and Cochrane Reviews was performed. 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. Confidence intervals were reported at 95%. Heterogeneity was assessed using the Q statistic and I 2 value., Results: The initial literature search resulted in 724 articles, of which 29 were deemed relevant on abstract review. Overall, 11 studies provided data for 376 patients with a pars interarticularis defect. Return to athletic competition, based on logit event rate, was found to be statistically favored after both nonoperative and operative treatment (92.2% vs 90.3%). There was no heterogeneity noted among the studies reporting nonoperative treatment ( Q value of 4.99 and I 2 value of 0). There was mild heterogeneity within the operative studies ( Q value of 3.54 and I 2 value of 15.18)., Conclusions: Adolescent athletes RTP 92.2% of the time with nonoperative management, compared with 90.3% when treated operatively, though both treatment groups strongly favor RTP. As this is the first study to pool results of all relevant literature, it provides strong evidence to guide decision making and help manage expectations in this unique patient population., Competing Interests: Declaration of Conflicting Interests: The author(s) declared no potential conflicts of interest with respect to the research, authorship, and/or publication of this article.

Study Design: A retrospective cohort study., Objective: The aim of this study was to investigate the effect depression has on the improvement of patient-reported outcome measures (PROMs) following lumbar decompression., Summary of Background Data: Decompression without fusion is a viable treatment option for lumbar spine stenosis. Depression reportedly has a negative impact on PROMs after certain types of spine surgery, though verification of this with new, more precise outcome measures is needed., Methods: We included consecutive adult patients who underwent lumbar decompression for lumbar spine stenosis between 2016 and 2017 who had PROM information system (PROMIS) physical function, pain, depression, and Oswestry Disability Index (ODI) questionnaires completed preoperatively and at 6-month follow-up. Patients with a PROMIS depression score >50 or <50 were allocated to the depressed and not depressed groups, respectively. The cohorts were compared using unpaired t tests and repeated-measures two-way analysis of variance (ANOVA) with statistical significance taken at P < 0.05., Results: The analysis included 55 patients without depression and 56 patients with depression. Depressed patients had worse preoperative PROMIS physical function (30.08 vs. 36.66, P = 0.005), PROMIS pain (69.36 vs. 64.69, P < 0.0001), and ODI scores (51.92 vs. 36.35, P < 0.0001). Similarly, the depressed group had worse postoperative PROMIS physical function (36.29 vs. 40.34, P = 0.005), PROMIS pain (60.16 vs. 54.87, P < 0.0001), and ODI scores (37.01 vs. 23.44, P = 0.0003). We observed a statistically significant interaction between depression status and pre to postoperative improvement in outcome for PROMIS physical function (F[1,109] = 102.5, P < 0.0001) and depression scores (F[1,109] = 15.38, P = 0.0002). No interaction was found for pain and ODI scores., Conclusion: Our results suggest that depressed patients experience a greater magnitude of improvement in PROMIS physical function and depression scores than nondepressed patients. Despite this, depressed patients have worse postoperative outcomes for PROMIS physical function, depression, pain, and ODI. These findings are important for risk stratifying and treating depressed patients before lumbar spine decompression., Level of Evidence: 3.

Background Context: Recombinant human bone morphogenetic protein 2 (rhBMP-2) plays a pivotal role in complex spine surgery. Despite its limited approval, the off-label use of rhBMP-2 is prevalent, particularly in transforaminal lumbar interbody fusions (TLIFs)., Purpose: To determine the effectiveness and safety of rhBMP-2 use in TLIF procedures versus autograft., Study Design: Retrospective cohort study., Patient Sample: Patients older than 18 years undergoing spine surgery for lumbar degenerative spine disease at a single academic institution., Outcome Measures: Clinical outcome was determined according to patient records. Radiographic outcome was determined according to plain X-rays and computed tomography (CT)., Methods: A retrospective study from 1997 to 2014 was conducted on 191 adults undergoing anterior-posterior instrumented spinal fusion with TLIF at a single academic institution. Patient data were gathered from operative notes, follow-up clinic notes, and imaging studies to determine complications and fusion rates. One hundred eighty-seven patients fit the criteria, which included patients with a minimum of one TLIF, and had a minimum 2-year radiographic and clinical follow-up. Patients were further classified into a BMP group (n=83) or non-BMP group (n=104). Three logistic regression models were run using rhBMP-2 exposure as the independent variable. The respective outcome variables were TLIF-related complications (radiculitis, seroma, osteolysis, and ectopic bone), surgical complications, and all complications., Results: Bone morphogenetic protein (n=83) and non-BMP (n=104) groups had similar baseline demographics (sex, diabetes, pre-existing cancer). On average, the BMP and non-BMP groups were similarly aged (51.9 vs. 47.9 years, p>.05), but the BMP group had a shorter follow-up time (3.03 vs. 4.06 years; p<.001) and fewer smokers (8 vs. 21 patients; p<.048). The fusion rate for the BMP and non-BMP groups was 92.7% and 92.3%, respectively. The pseudoarthrosis rate was 7.5% (14 of 187 patients). Radiculitis was observed in seven patients in the BMP group (8.4%) and two patients in the non-BMP group (1.9%). Seroma was observed in two patients in the BMP group (2.4%) and none in the non-BMP group. No deep infections were observed in the BMP group, and in one patient in the non-BMP group (0.96%). Although patients exposed to BMP were at a significantlygreater risk of developing radiculitis and seroma (odds ratio [OR]=4.53, confidence interval [CI]=1.42-14.5), BMP exposure was not a significant predictor of surgical complications (OR=0.32, CI=0.10-1.00) or overall complications (OR=1.11, CI=0.53-2.34). The outcome of TLIF-related complications was too rare and the confidence interval too wide for practical significance of the first model., Conclusion: Evidence supports the hypothesis that off-label use of rhBMP-2 in TLIF procedures is relatively effective for achieving bone fusion at rates similar to patients receiving autograft. Patients exhibited similar complication rates between the two groups, with the BMP group exhibiting slightly higher rates of radiculitis and seroma., (Copyright © 2017 Elsevier Inc. All rights reserved.)

Study Design: Cost-effectiveness analysis., Objectives: To determine the 7-year cost-effectiveness of cervical disc replacement (CDR) and anterior cervical discectomy and fusion (ACDF)., Methods: We analyzed 7-year Short Form-36 Health Survey data collected from the Prestige Cervical Disc investigational device exemption study (IDE). The SF-6D algorithm was used to convert this data into health state utilities. Costs were calculated from the payer perspective, and quality adjusted life years (QALYs) were used to represent effectiveness. A Markov transition-state model was used to evaluate the cost-effectiveness of single-level CDR versus ACDF, and a Monte Carlo simulation was performed to assess the probabilistic sensitivity of the model., Results: CDR generated a 7-year cost of $172 989 compared to a 7-year cost of $143 714 for ACDF. CDR generated 4.53 QALYs compared to 3.85 QALYs generated by ACDF. The cost-effectiveness ratio of CDR was $38 247/QALY, while the cost-effectiveness ratio of ACDF was $37 325/QALY. The incremental cost-effectiveness ratio of CDR was $43 522/QALY, under the willingness to pay threshold of $50 000/QALY. Our probabilistic sensitivity analysis demonstrated CDR would be chosen 56% of the time based on 10 000 simulations., Conclusions: Single-level CDR and ACDF were both cost-effective strategies at 7 years for treating degenerative conditions of the cervical spine. Both the Markov simulation and the Monte Carlo simulation demonstrate CDR to be the more cost-effective strategy at 7 years. Continued analysis of IDE data should be performed to validate long-term cost-effectiveness of these treatment strategies., Competing Interests: Declaration of Conflicting Interests: The author(s) declared no potential conflicts of interest with respect to the research, authorship, and/or publication of this article.

Study Design: Retrospective cohort study., Objectives: To determine the incidence of index level fusion following open or minimally invasive lumbar microdiscectomy., Methods: We conducted a retrospective review of 174 patients with a symptomatic single-level lumbar herniated nucleus pulposus who underwent microdiscectomy via a mini-open approach (MIS; 39) or through a minimally invasive dilator tube (135). Outcomes of interest included revision microdiscectomy and the ultimate need for index level fusion. Continuous variables were analyzed with independent sample t test, and χ 2 analysis was used for categorical data. A multivariate regression analysis was performed to identify predictive factors for patients that required index level fusion after lumbar microdiscectomy., Results: There was no difference in patient demographics in the open and MIS groups aside from length of follow-up (60.4 vs 40.03 months, P < .0001) and body mass index (24.72 vs 27.21, P = .03). The rate of revision microdiscectomy was not statistically significant between open and MIS approaches (10.3% vs 10.4%, P = .90). The rate of patients who ultimately required index level fusion approached significance, but was not statistically different between open and MIS approaches (10.3% vs 4.4%, P = .17). Multivariate regression analysis indicated that the need for eventual index level fusion after lumbar microdiscectomy was statistically predicted in smokers and those patients who underwent revision microdiscectomy ( P < .05) in both open and MIS groups., Conclusions: Our results suggest a low likelihood of patients ultimately requiring fusion following microdiscectomy with predictors including smoking status and a history of revision microdiscectomy., Competing Interests: Declaration of Conflicting Interests: The author(s) declared no potential conflicts of interest with respect to the research, authorship, and/or publication of this article.

Study Design: Health utility analysis., Objectives: To determine the health state utility (HSU) of 1- and 2-level anterior cervical discectomy and fusion (ACDF) and cervical disc replacement (CDR)., Methods: Data from the Medtronic Prestige Cervical Disc investigational device exemption studies was used. Four groups were defined: 1-level ACDF, 1-level CDR, 2-level ACDF, and 2-level CDR. The 36-item Short Form Health Survey (SF-36) was collected at baseline, 12 months, 24 months, 36 months, and 60 months postoperatively and converted into utility scores for each time point. A repeated-measures 1-way analysis of variance (ANOVA) was used to detect differences among groups. Tukey's method for multiple comparisons was used to determine which means within the groups were statistically different ( P < .05)., Results: We found a statistically significant difference in HSU among groups as determined by repeated-measures 1-way ANOVA ( P = .0008). Post hoc analysis indicated that 1-level ACDF had a statistically lower utility score compared with 1- and 2-level CDR ( P = .04 and P = .02, respectively). Similarly, 2-level ACDF had lower utility values compared with 2-level CDR ( P = .010). One-level ACDF utility values were not different from 2-level ACDF values ( P = .55). Similarly, 1-level CDR and 2-level CDR did not have different utility values ( P = .67)., Conclusions: Overall, CDR had higher health state utility scores for 1- and 2-level procedures at every time point. This study indicates that CDR results in a higher postoperative health utility state than ACDF, and may therefore be an effective alternative to ACDF for treating degenerative conditions of the cervical spine., Competing Interests: Declaration of Conflicting Interests: The author(s) declared no potential conflicts of interest with respect to the research, authorship, and/or publication of this article.

Background Context: Anterior cervical discectomy and fusion (ACDF) and cervical disc replacement (CDR) are both acceptable surgical options for the treatment of cervical myelopathy and radiculopathy. To date, there are limited economic analyses assessing the relative cost-effectiveness of two-level ACDF versus CDR., Purpose: The purpose of this study was to determine the 5-year cost-effectiveness of two-level ACDF versus CDR., Study Design: The study design is a secondary analysis of prospectively collected data., Patient Sample: Patients in the Prestige cervical disc investigational device exemption (IDE) study who underwent either a two-level CDR or a two-level ACDF were included in the study., Outcome Measures: The outcome measures were cost and quality-adjusted life years (QALYs)., Materials and Methods: A Markov state-transition model was used to evaluate data from the two-level Prestige cervical disc IDE study. Data from the 36-item Short Form Health Survey were converted into utilities using the short form (SF)-6D algorithm. Costs were calculated from the payer perspective. QALYs were used to represent effectiveness. A probabilistic sensitivity analysis (PSA) was performed using a Monte Carlo simulation., Results: The base-case analysis, assuming a 40-year-old person who failed appropriate conservative care, generated a 5-year cost of $130,417 for CDR and $116,717 for ACDF. Cervical disc replacement and ACDF generated 3.45 and 3.23 QALYs, respectively. The incremental cost-effectiveness ratio (ICER) was calculated to be $62,337/QALY for CDR. The Monte Carlo simulation validated the base-case scenario. Cervical disc replacement had an average cost of $130,445 (confidence interval [CI]: $108,395-$152,761) with an average effectiveness of 3.46 (CI: 3.05-3.83). Anterior cervical discectomy and fusion had an average cost of $116,595 (CI: $95,439-$137,937) and an average effectiveness of 3.23 (CI: 2.84-3.59). The ICER was calculated at $62,133/QALY with respect to CDR. Using a $100,000/QALY willingness to pay (WTP), CDR is the more cost-effective strategy and would be selected 61.5% of the time by the simulation., Conclusions: Two-level CDR and ACDF are both cost-effective strategies at 5 years. Neither strategy was found to be more cost-effective with an ICER greater than the $50,000/QALY WTP threshold. The assumptions used in the analysis were strongly validated with the results of the PSA., (Copyright © 2017 Elsevier Inc. All rights reserved.)

Study Design: Systematic literature review and meta-analysis of studies published in English language., Objective: Return to play after anterior cervical discectomy and fusion (ACDF) in contact athletes remains a controversial topic with no consensus opinion in the literature. Additional information is needed to properly advise and treat this population of patients. This study is a meta-analysis assessing return to competitive contact sports after undergoing an ACDF., Methods: A literature search of Medline, Embase, and Cochrane Reviews was performed to identify investigations reporting return to play following ACDF in professional contact athletes. The pooled results were performed by calculating the effect size based on the logic event rate. Studies were weighted by the inverse of the variance, which included both within and between-study error. Confidence intervals (CIs) were reported at 95%. Heterogeneity was assessed using the Q statistic and I 2 . Sensitivity analysis and publication bias calculations were performed., Results: The initial literature search resulted in 166 articles, of which 5 were determined relevant. Overall, return to play data was provided for 48 patients. The pooled clinical success rate for return to play was 73.5% (CI = 56.7%, 85.8%). The logit event rate was calculated to be 1.036 (CI = 0.270, 1.802), which was statistically significant ( P = .008). The studies included in this meta-analysis demonstrated minimal heterogeneity with Q value of 4.038 and I 2 value of 0.956., Conclusions: Elite contact athletes return to competition 73.5% of the time after undergoing ACDF. As this is the first study to pool results from existing studies, it provides strong evidence to guide decision making and expectations in this patient population., Competing Interests: Declaration of Conflicting Interests: The author(s) declared no potential conflicts of interest with respect to the research, authorship, and/or publication of this article.

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.

Background: Bilateral C5 motor palsy is a rare but potentially debilitating complication after cervical spine decompression with very few reports in the published literature., Purpose: To present a case of bilateral C5 motor palsy after anterior cervical decompression and fusion and discuss the incidence and risk factors of this complication., Study Design/setting: We report a case of a 57-year-old male who underwent a three level C3-C6 anterior cervical discectomy and fusion with instrumentation who developed a postoperative bilateral C5 motor palsy., Methods: A review of the literature was performed regarding reports on and incidence of post-operative bilateral C5 palsy following either anterior or posterior cervical spine decompression., Results: Bilateral C5 motor palsy is a rare complication of cervical spine decompression with an overall incidence of 0.38%. Although a group of risk factors have been suggested no single cause has been identified., Conclusions: Bilateral C5 motor palsy is a rare but debilitating complication of cervical decompression.

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.

Study Design  Observational study. Objective  Studies have shown a correlation between obesity and lumbar spine pathology, but also that obese patients have higher rates of complication following lumbar spine surgery. It is unknown if obese patients have clinical gains following lumbar spine surgery comparable to the gain of normal-weight patients. This study investigated the correlation of obesity and the delta change in outcomes in a single surgeon's cohort of normal-weight and obese patients undergoing minimally invasive (MIS) transforaminal lumbar interbody fusion (TLIF). Methods  A retrospective review was performed of a single surgeon's patients at an academic medical center who underwent MIS TLIF between July 2011 and December 2013. Statistical analyses included independent sample t test for continuous variables, Fisher exact test for categorical data, and repeated measures two-way analysis of variance to assess the interaction between obesity status and the change in Short-Form Health Survey 12 (SF-12) results. Results  Thirty-eight patients from a single institution were reviewed, and 19 had a body mass index greater than 30. The nonobese and obese postoperative SF-12 mental composite scores (MCS; 52.70 ± 2.50 versus 52.16 ± 1.91; p  = 0.87) and physical composite scores (PCS; 45.56 ± 2.72 versus 41.03 ± 2.65; p  = 0.24) did not show any significant differences. There was no significant interaction between obesity and change in SF-12 MCS ( F [1, 36] = 0.96, p  = 0.33) or SF-12 PCS ( F [1, 36] = 0.74, p  = 0.40) between the pre- and postoperative scores. There was a significant effect of obesity on SF-12 PCS scores ( F [1, 36] = 7.15, p  = 0.01). Conclusions  Patients undergoing MIS TLIF sustain meaningful and significant gains in SF-12 MCS and PCS that is not impacted by their obesity status.

Introduction: The minimally invasive posterior cervical foraminotomy, a motion-preserving procedure, is an excellent treatment for patients with unilateral radiculopathy secondary to a laterally located herniated disc or foraminal stenosis., Step 1 Position the Patient Video 1: Place the patient in a prone position on a Jackson table with 6 posts and with the head resting comfortably on a soft facial pillow, and tape the shoulders down to provide traction to the skin and help with fluoroscopic visualization of the lower cervical levels., Step 2 Perform the Skin Incision: Make the skin incision adjacent to the spinous process on the side of the abnormality over the operative level., Step 3 Use Tubular Dilators to Make a Working Portal: Use sequential dilators to create a working portal and secure the working tube overlying the lamina-facet junction of the operative level., Step 4 Perform the Laminoforaminotomy Video 2: Perform the laminoforaminotomy with the use of a high-speed drill and a Kerrison rongeur to create a working window into the foramen., Step 5 Perform the Foraminal Decompression Video 3: Use a nerve hook to superiorly retract the nerve root, and perform a discectomy and decompression., Step 6 Wound Closure and Postoperative Care: Obtain hemostasis with electrocautery or hemostatic foam and close the wound with a standard layered closure., Results: A systematic review and meta-analysis of studies on open or minimally invasive surgical (MIS) techniques for posterior cervical foraminotomy showed a pooled clinical success rate of 92.7% for the 509 patients managed with the open technique and 94.9% for the 208 patients who had the MIS technique; the difference was not significant (p = 0.418) 2 .

Study Design: Systematic literature review and meta-analysis of English language studies., Objective: This study is a meta-analysis assessing elite athlete's return-to-play (RTP) rates after a lumbar herniated nucleus pulposus (HNP) treated with microdiscectomy. Additionally, we compare RTP rates of those treated operatively versus nonoperatively., Summary of Background Data: Microdiscectomy for a lumbar HNP in elite athletes remains a controversial subject with no consensus in the literature regarding true RTP., Methods: A literature search of Medline, Embase, and Cochrane Reviews was performed. The pooled results were analyzed 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., Results: The initial literature search resulted in 547 articles, of which 14 were determined relevant on abstract review. Overall, nine studies provided data for 558 patients who underwent a lumbar microdiscectomy. The pooled clinical success rate was 83.5% (CI: 79.7%, 88.0%), which was statistically significant (P < 0.0001). The studies demonstrated minimal heterogeneity Q value of 7.41 and I value of 5.53. Four studies included operative and nonoperative cohorts. The odds ratio of RTP with a symptomatic lumbar disc herniation was 1.13 (CI: 0.37-5.90). There was no statistical difference in RTP between the two groups (P = 0.59)., Conclusion: Elite athletes return to competition 83.5% of the time after undergoing a single level lumbar microdiscectomy. Additionally, when comparing lumbar microdiscectomy to non-operative treatment, there is no difference in RTP rates, suggesting that a more aggressive approach to managing a symptomatic HNP in this population with earlier surgical intervention may be employed judiciously if timing necessitates for the athlete's benefit., Level of Evidence: 3.

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.

Background Context: Live mesenchymal stem cell (MSC) allograft-containing allogeneic bone grafts have recently gained popularity and currently account for greater than 17% of all bone grafts and bone graft substitutes used in spinal surgery. Although the claim of cellular bone matrices containing osteogenic cells with osteoinductive properties is attractive, little is known about their clinical success when used in anterior cervical discectomy and fusion (ACDF)., Purpose: The objective of this study was to report on the radiographic fusion rates in one- and two-level instrumented ACDF using an MSC., Study Design/setting: This was a retrospective review of prospectively matched cohort of patients with radiologic assessment of fusion as the primary end point., Patient Sample: Two matched cohorts of adult patients who underwent ACDF with MSC or standard allograft were included., Outcomes Measures: The outcome measures included radiographic and clinical evidence of healing at 1 year., Methods: A consecutive series of 57 patients who underwent a one- or two-level instrumented ACDF procedure between 2010 and 2012 were retrospectively analyzed. All fusion constructs comprised an interbody allograft, an anterior plate, and Osteocel (NuVasive, San Diego, CA, USA). These patients were matched to a control group of 57 patients., Results: Of the 57 cases in both cohorts, 29 (50.9%) were single-level, and 28 (49.1%) were two-level instrumented ACDFs. There were no significant differences in patient age (p=.71), gender, comorbidity burden (Charlson Comorbidity Index [CCI]: 1.95; 2.42, p=.71) or body mass index (p=.79). At the 1-year follow-up, 50 of 57 (87.7%) patients in the Osteocel cohort demonstrated a solid fusion compared with 54 of 57 (94.7%) in the control group (p=.19). Seven (12.3%) patients in the Osteocel cohort were reported as having a failed fusion at 1 year., Conclusions: This is the first non-industry sponsored study to analyze a matched cohort assessing the 1-year arthrodesis rates associated with a nonstructural MSC allograft in one- and two-level ACDF procedures. Although not statistically significant, patients treated with MSC allografts demonstrated lower fusion rates compared with a matched non-MSC cohort., (Copyright © 2016 Elsevier Inc. All rights reserved.)

Background Context: In recent years, there has been an increase in the number of decision analysis studies in the spine literature. Although there are several published reviews on the different types of decision analysis (cost-effectiveness, cost-benefit, cost-utility), there is limited information in the spine literature regarding the mathematical models used in these studies (decision tree, Markov modeling, Monte Carlo simulation)., Purpose: The purpose of this review was to provide an overview of the types of decision analytic models used in spine surgery. A secondary aim was to provide a systematic overview of the most cited studies in the spine literature., Study Design/setting: This is a systematic review of the available information from all sources regarding decision analytics and economic modeling in spine surgery., Methods: A systematic search of PubMed, Embase, and Cochrane review was performed to identify the most relevant peer-reviewed literature of decision analysis/cost-effectiveness analysis (CEA) models including decisions trees, Markov models, and Monte Carlo simulations. Additionally, CEA models based on investigational drug exemption studies were reviewed in particular detail, as these studies are prime candidates for economic modeling., Results: The initial review of the literature resulted in 712 abstracts. After two reviewer-assessment of abstract relevance and methodologic quality, 19 studies were selected: 12 with decision tree constructs and 7 with Markov models. Each study was assessed for methodologic quality and a review of the overall results of the model. A generalized overview of the mathematical construction and methodology of each type of model was also performed. Limitations, strengths, and potential applications to spine research were further explored., Conclusions: Decision analytic modeling represents a powerful tool both in the assessment of competing treatment options and potentially in the formulation of policy and reimbursement. Our review provides a generalized overview and a conceptual framework to help spine physicians with the construction of these models., (Copyright © 2015 Elsevier Inc. All rights reserved.)

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., (Copyright © 2015 Elsevier Inc. All rights reserved.)

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.

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.

Study Design Cross-sectional study. Objective To assess the current practices of spine surgeons performing ambulatory surgery in the United States. Methods An electronic survey was distributed to members of the International Society for the Advancement of Spine Surgery. Data were initially examined in a univariate manner; variables with a p value < 0.25 were entered into a multiple logistic regression model. All statistical analyses were performed using the SAS System software Version 9.2 (SAS Institute, Inc., Cary, North Carolina, United States). Results Overall, 84.2% of respondents performed some manner of ambulatory spine surgery, and 49.1% were investors in an ambulatory surgery center. Surgeon investors in ambulatory surgery centers were more likely to perform procedures of increased complexity than noninvestors, though limited data precluded a statistical correlation. Surgeons in private practice were more likely to perform ambulatory surgery (94.3%; p = 0.0176), and nonacademic surgeons were both more likely to invest in ambulatory surgery centers (p = 0.0024) and perform surgery at least part of the time in a surgery center (p = 0.0039). Conclusions Though the numbers were too few to calculate statistical significance, there was a trend toward the performance of high-risk procedures on an ambulatory basis being undertaken by those with investment status in an ambulatory center. It is possible that this plays a role in the decision to perform these procedures in this setting versus that of a hospital, where a patient may have better access to care should a complication arise requiring emergent assessment and treatment by a physician. This decision should divest itself of financial incentives and focus entirely on patient safety.

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.

C5 nerve root palsy is a rare and potentially debilitating complication of cervical spine surgery. Currently, however, there are no guidelines to help surgeons to prevent or treat this complication. We carried out a systematic review of the literature to identify the causes of this complication and options for its prevention and treatment. Searches of PubMed, Embase and Medline yielded 60 articles for inclusion, most of which addressed C5 palsy as a complication of surgery. Although many possible causes were given, most authors supported posterior migration of the spinal cord with tethering of the nerve root as being the most likely. Early detection and prevention of a C5 nerve root palsy using neurophysiological monitoring and variations in surgical technique show promise by allowing surgeons to minimise or prevent the incidence of C5 palsy. Conservative treatment is the current treatment of choice; most patients make a full recovery within two years., (©2014 The British Editorial Society of Bone & Joint Surgery.)

Study Design: Epidemiologic study., Objective: To compare the utilization of anterior cervical discectomy and fusion (ACDF) versus cervical disc arthroplasty (CDA) in terms of patient and hospital characteristics during the 3 years after Food and Drug Administration (FDA) approval of CDA devices in 2007., Summary of Background Data: There was a surge in CDA adoption in the 3 years prior to FDA approval of CDA devices in 2007. However, utilization trends of CDA versus ACDF since the FDA approval are unknown., Methods: The Nationwide Inpatient Sample database was used to identify CDA and ACDF procedures performed in the United States in the 3 years after FDA approval of CDA devices (2008-2010). The frequencies of CDA and ACDF were estimated, stratified by patient and hospital characteristics. Average length of hospital stay and total charges and costs were estimated. Multivariable analysis was performed to identify patient and hospital characteristics associated with CDA utilization., Results: In the 3 years after FDA approval of cervical disc devices, population-adjusted growth rates for CDA and ACDF were 4.9% and 11.8%, respectively (P = 0.6977). Female, African American and Medicaid patients were less likely to receive CDA. CDA was less likely to be performed in patients with cervical spondylotic changes and more likely to be performed in younger and healthier patients. CDA was less likely to be performed in the Midwestern United States or in public hospitals., Conclusion: The prevalence of CDA increased in the 3 years after FDA approval with a growth rate that is approximately twice than that for ACDF. Although there seems to be CDA adoption, CDA growth seemed to have reached a plateau and ACDF still remained the dominant surgical strategy for cervical disc disease. Possible regional, racial, and sex disparities in CDA utilization and a more strict approach in the selection of CDA over traditional ACDF may have impeded rapid adoption of CDA., Level of Evidence: 3.