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

PURPOSE: Integrating machine learning models into electronic medical record systems can greatly enhance decision-making, patient outcomes, and value-based care in healthcare systems. Challenges related to data accessibility, privacy, and sharing can impede the development and deployment of effective predictive models in spine surgery. Federated learning (FL) offers a decentralized approach to machine learning that allows local model training while preserving data privacy, making it well-suited for healthcare settings. Our objective was to describe federated learning solutions for enhanced predictive modeling in spine surgery. METHODS: The authors reviewed the literature. RESULTS: FL has promising applications in spine surgery, including telesurgery, AI-based prediction models, and medical image segmentation. Implementing FL requires careful consideration of infrastructure, data quality, and standardization, but it holds the potential to revolutionize orthopedic surgery while ensuring patient privacy and data control. CONCLUSIONS: Federated learning shows great promise in revolutionizing predictive modeling in spine surgery by addressing the challenges of data privacy, accessibility, and sharing. The applications of FL in telesurgery, AI-based predictive models, and medical image segmentation have demonstrated their potential to enhance patient outcomes and value-based care.

Impact of age on comparative outcomes of decompression alone versus fusion for L4 degenerative spondylolisthesis.

PURPOSE: To compare the outcomes of decompression alone and fusion for L4-5 DLS in different age cohorts (< 70 years, ≥ 70 years). METHODS: This retrospective cohort study included patients who underwent minimally invasive decompression or fusion for L4-5 DLS and had a minimum of 1-year follow-up. Outcome measures were: (1) patient-reported outcome measures (PROMs) (Oswestry Disability Index, ODI; Visual Analog Scale back and leg, VAS; 12-Item Short Form Survey Physical Component Score, SF-12 PCS), (2) minimal clinically important difference (MCID), (3) patient acceptable symptom state (PASS), (4) response on the global rating change (GRC) scale, and (5) complication rates. The decompression and fusion groups were compared for outcomes separately in the < 70-year and ≥ 70-year age cohorts. RESULTS: 233 patients were included, out of which 52% were < 70 years. Patients < 70 years showed non-significant improvement in SF-12 PCS and significantly lower MCID achievement rates for VAS back after decompression compared to fusion. Analysis of the ≥ 70-year age cohort showed no significant differences between the decompression and fusion groups in the improvement in PROMs, MCID/PASS achievement rates, and responses on GRC. Patients ≥ 70 years undergoing fusion had significantly higher in-hospital complication rates. When analyzed irrespective of the surgery type, both < 70-year and ≥ 70-year age cohorts showed significant improvement in PROMs with no significant difference. CONCLUSIONS: Patients < 70 years undergoing decompression alone did not show significant improvement in physical function and had significantly less MCID achievement rate for back pain compared to fusion. Patients ≥ 70 years showed no difference in outcomes between decompression alone and fusion.

Preoperative cross-sectional area of psoas muscle correlates with short-term functional outcomes after posterior lumbar surgery.

PURPOSE: To determine the optimal level for the measurement of psoas cross-sectional area and examine the correlation with short-term functional outcomes of posterior lumbar surgery. METHODS: Patients who underwent minimally invasive posterior lumbar surgery were included in this study. The cross-sectional area of psoas muscle was measured at each intervertebral level on T2-weighted axial images of preoperative MRI. Normalized total psoas area (NTPA) (mm2/m2) was calculated as total psoas area normalized to patient height. Intraclass Correlation Coefficient (ICC) was calculated for the analysis of inter-rater reliability. Patient reported outcome measures including Oswestry disability index (ODI), visual analog scale (VAS), short form health survey (SF-12) and patient-reported outcomes measurement information system were collected. A multivariate analysis was performed to elucidate independent predictors associated with failure to reach minimal clinically important difference (MCID) in each functional outcome at 6 months. RESULTS: The total of 212 patients were included in this study. ICC was highest at L3/4 [0.992 (95% CI: 0.987-0.994)] compared to the other levels [L1/2 0.983 (0.973-0.989), L2/3 0.991 (0.986-0.994), L4/5 0.928 (0.893-0.952)]. Postoperative PROMs were significantly worse in patients with low NTPA. Low NTPA was an independent predictor of failure to reach MCID in ODI (OR = 2.68; 95% CI: 1.26-5.67; p = 0.010) and VAS leg (OR = 2.43; 95% CI: 1.13-5.20; p = 0.022). CONCLUSION: Decreased psoas cross-sectional area on preoperative MRI correlated with functional outcomes after posterior lumbar surgery. NTPA was highly reliable, especially at L3/4.

Improvement following minimally invasive transforaminal lumbar interbody fusion in patients aged 70 years or older compared with younger age groups.

OBJECTIVE: The goal of this study was to assess the outcomes of minimally invasive transforaminal lumbar interbody fusion (MI-TLIF) in patients ≥ 70 years old and compare them to younger age groups. METHODS: This was a retrospective study of data that were collected prospectively. Patients who underwent primary single-level MI-TLIF were included and divided into 3 groups: age < 60, 60-69, and ≥ 70 years. The outcome measures were as follows: 1) patient-reported outcome measures (PROMs) (i.e., visual analog scale [VAS] for back and leg pain, Oswestry Disability Index [ODI], 12-Item Short-Form Health Survey Physical Component Summary [SF-12 PCS]); 2) minimum clinically important difference (MCID) achievement; 3) return to activities; 4) opioid discontinuation; 5) fusion rates; and 6) complications/reoperations. RESULTS: A total of 147 patients (age < 60 years, 62; 60-69 years, 47; ≥ 70 years, 38) were included. All the groups showed significant improvements in all PROMs at the early (< 6 months) and late (≥ 6 months) time points and there was no significant difference between the groups. Although MCID achievement rates for VAS leg and ODI were similar, they were lower in the ≥ 70-year-old patient group for VAS back and SF-12 PCS. Although the time to MCID achievement for ODI and SF-12 PCS was similar, it was greater in the ≥ 70-year-old patient group for VAS back and leg. There was no significant difference between the groups in terms of return to activities, opioid discontinuation, fusion rates, and complication/reoperation rates. CONCLUSIONS: Although patients > 70 years of age may be less likely and/or take longer to achieve MCID compared to their younger counterparts, they show an overall significant improvement in PROMs, a similar likelihood of returning to activities and discontinuing opioids, and comparable fusion and complication/reoperation rates following MI-TLIF.

Does robot-assisted navigation influence pedicle screw selection and accuracy in minimally invasive spine surgery?

OBJECTIVE: The accuracy of percutaneous pedicle screw placement has increased with the advent of robotic and surgical navigation technologies. However, the effect of robotic intraoperative screw size and trajectory templating remains unclear. The purpose of this study was to compare pedicle screw sizes and accuracy of placement using robotic navigation (RN) versus skin-based intraoperative navigation (ION) alone in minimally invasive lumbar fusion procedures. METHODS: A retrospective cohort study was conducted using a single-institution registry of spine procedures performed over a 4-year period. Patients who underwent 1- or 2-level primary or revision minimally invasive surgery (MIS)-transforaminal lumbar interbody fusion (TLIF) with pedicle screw placement, via either robotic assistance or surgical navigation alone, were included. Demographic, surgical, and radiographic data were collected. Pedicle screw type, quantity, length, diameter, and the presence of endplate breach or facet joint violation were assessed. Statistical analysis using the Student t-test and chi-square test was performed to evaluate the differences in pedicle screw sizes and the accuracy of placement between both groups. RESULTS: Overall, 222 patients were included, of whom 92 underwent RN and 130 underwent ION MIS-TLIF. A total of 403 and 534 pedicle screws were placed with RN and ION, respectively. The mean screw diameters were 7.25 ± 0.81 mm and 6.72 ± 0.49 mm (p < 0.001) for the RN and ION groups, respectively. The mean screw length was 48.4 ± 4.48 mm in the RN group and 45.6 ± 3.46 mm in the ION group (p < 0.001). The rates of "ideal" pedicle screws in the RN and ION groups were comparable at 88.5% and 88.4% (p = 0.969), respectively. The overall screw placement was also similar. The RN cohort had 63.7% screws rated as good and 31.4% as acceptable, while 66.1% of ION-placed screws had good placement and 28.7% had acceptable placement (p = 0.661 and p = 0.595, respectively). There was a significant reduction in high-grade breaches in the RN group (0%, n = 0) compared with the ION group (1.2%, n = 17, p = 0.05). CONCLUSIONS: The results of this study suggest that robotic assistance allows for placement of screws with greater screw diameter and length compared with surgical navigation alone, although with similarly high accuracy. These findings have implied that robotic platforms may allow for safe placement of the "optimal screw," maximizing construct stability and, thus, the ability to obtain a successful fusion.

The association between spondylolisthesis and decreased muscle health throughout the lumbar spine for patients with operative lumbar spinal stenosis.

PURPOSE: There are data underlining the relationship between muscle health and spine related pathology, but little data regarding changes in paralumbar muscle associated with lumbar spondylolisthesis. We aimed to define changes in paralumbar muscle health associated with spondylolisthesis. METHODS: A retrospective review was performed on consecutive patients with lumbar spine pathology requiring an operation. A pre-operative lumbar MRI was analysed for muscle health measurements including lumbar indentation value (LIV), paralumbar cross-sectional area divided by body mass index (PL-CSA/BMI), and Goutallier classification of fatty atrophy. All measurements were taken from an axial slice of a T2-weighted image at lumbar disc spaces. Baseline health-related quality of life scores (HRQOLs), narcotic use and areas of stenosis were tracked. We performed Chi-square analyses and student's t test to determine statistically significant differences between cohorts. RESULTS: There were 307 patients (average age 56.1 ± 16.7 years, 141 females) included within our analysis. 112 patients had spondylolisthesis. There were no differences in baseline HRQOLs between the spondylolisthesis cohort (SC) and non-spondylolisthesis cohort (non-SC). There were significantly worse PL-CSA/BMI at L2-L3 (p = 0.03), L3-L4 (p = 0.04) and L4-L5 (p = 0.02) for the SC. Goutallier classification of paralumbar muscle was worse for SC at L1-L2 (p = 0.04) and at L4-L5 (p < 0.001). Increased grade of spondylolisthesis was associated with worse PL-CSA at L1-L2 (p = 0.02), L2-L3 (p = 0.03) and L3-L4 (p = 0.05). Similarly, there were worse Goutallier classification scores associated with higher-grade spondylolisthesis at all levels (p < 0.05). CONCLUSION: There are significant detrimental changes to paralumbar muscle health throughout the lumbar spine associated with spondylolisthesis.

Morphometric analysis of cervical interlaminar space for posterior surgical approach and decompression.

PURPOSE: The purpose of this study is to provide a morphometric description of the bony margins of the interlaminar spaces by level in the cervical spine for guidance of safe posterior cervical surgical dissection and decompression. We also aim to describe the impact of increasing static cervical lordosis on the overlap between the lamina. METHODS: Morphometric measurements of the interlaminar space were performed on 100 consecutive cervical spine CT scans of patients ranging in age from 18 to 50 years were selected. Three raters performed measurements of the interlaminar height measured using two techniques (true interlaminar height and surgical interlaminar height), and interlaminar width from C2-C3 to C7-T1. RESULTS: In total, 100 patients were included. The true interlaminar height was greatest at C2-3, C3-4, C4-5 (5.2 ± 1.4-1.8 mm) and smallest at C6-7 (4.4 ± 1.3 mm). Surgical interlaminar height was greatest at C3-4 (4.2 ± 1.7) and smallest at C6-7 (3.0 ± 1.3 mm). The widest interlaminar space was observed at C3-4 (27.1 ± 2.1 mm) and most narrow at C7-T1 (20.9 ± 2.4 mm). Following multivariate regression, male gender was associated with greater interlaminar widths at each cervical level between C4 and T1 (Table 2). While greater patient height was associated with larger interlaminar height (true and surgical) and width at C2-3 and C4-5, weight was not independently associated with the interlaminar measurements. Increasing C2-C7 lordosis was significantly associated with decreasing true and surgical interlaminar heights at all levels except C7-T1, but was not associated with differences between interlaminar width. CONCLUSION: The study provides a morphometric analysis of interlaminar anatomy in the cervical spine. Surgeons can apply this information in their pre-operative plan to safely approach the posterior cervical spine.

Does interbody cage lordosis impact actual segmental lordosis achieved in minimally invasive lumbar spine fusion?

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.

Opioid-free anesthesia within an enhanced recovery after surgery pathway for minimally invasive lumbar spine surgery: a retrospective matched cohort study.

OBJECTIVEEnhanced recovery after surgery (ERAS) and multimodal analgesia are established care models that minimize perioperative opioid consumption and promote positive outcomes after spine surgery. Opioid-free anesthesia (OFA) is an emerging technique that may achieve similar goals. The purpose of this study was to evaluate an OFA regimen within an ERAS pathway for lumbar decompressive surgery and to compare perioperative opioid requirements in a matched cohort of patients managed with traditional opioid-containing anesthesia (OCA).METHODSThe authors performed a retrospective analysis of prospectively collected data. They included 36 patients who underwent lumbar decompression under their ERAS pathway for spinal decompression between February and August 2018. Eighteen patients who received OFA were matched in a 1:1 ratio to a cohort managed with a traditional OCA regimen. The primary outcome was total perioperative opioid consumption. Postoperative pain scores (measured using the numerical rating scale [NRS]), opioid consumption (total morphine equivalents), and length of stay (time to readiness for discharge) were compared in the postanesthesia care unit (PACU). The authors also assessed compliance with ERAS process measures and compared compliance during 3 phases of care: pre-, intra-, and postoperative.RESULTSThere was a significant reduction in total perioperative opioid consumption in patients who received OFA (2.43 ± 0.86 oral morphine equivalents [OMEs]; mean ± SEM), compared to patients who received OCA (38.125 ± 6.11 OMEs). There were no significant differences in worst postoperative pain scores (NRS scores 2.55 ± 0.70 vs 2.58 ± 0.73) or opioid consumption (5.28 ± 1.7 vs 4.86 ± 1.5 OMEs) in the PACU between OFA and OCA groups, respectively. There was a clinically significant decrease in time to readiness for discharge from the PACU associated with OFA (37 minutes), although this was not statistically significantly different. The authors found high overall compliance with ERAS process measures (91.4%) but variation in compliance according to phase of care. The highest compliance occurred during the preoperative phase (94.71% ± 2.88%), and the lowest compliance occurred during the postoperative phase of care (85.4% ± 5.7%).CONCLUSIONSOFA within an ERAS pathway for lumbar spinal decompression represents an opportunity to minimize perioperative opioid exposure without adversely affecting pain control or recovery. This study reveals opportunities for patient and provider education to reinforce ERAS and highlights the postoperative phase of care as a time when resources should be focused to increase ERAS adherence.

An enhanced recovery after surgery pathway: association with rapid discharge and minimal complications after anterior cervical spine surgery.

OBJECTIVEEnhanced recovery after surgery (ERAS) pathways are associated with improved outcomes, lower morbidity and complications, and higher patient satisfaction in multiple surgical subspecialties. Despite these gains, there are few data to guide the application of ERAS concepts to spine surgery. The authors report the development and implementation of the first ERAS pathway for patients undergoing anterior cervical discectomy and fusion (ACDF) and cervical disc arthroplasty (CDA).METHODSThis was a retrospective cohort study of prospectively collected data. The authors created a multidisciplinary pathway based on best available evidence for interventions that positively influence outcomes after anterior cervical spine surgery. Patients were followed prospectively up to postoperative day 90. Patient data were collected via electronic medical record review and included demographics, comorbidities, baseline and perioperative opioid use, postoperative complications, and length of hospital stay (LOS). ERAS process measures and compliance with pathway elements were also tracked.RESULTSThirty-three patients were cared for under the pathway (n = 25 ACDF; n = 8 CDA). The median LOS was 416 minutes (interquartile range [IQR] 210-1643 minutes). Eight patients required an extended stay-longer than 23 hours. Reasons for extended admission included pain (n = 4), dyspnea (n = 1), hypoxia (n = 1), hypertension (n = 1), and dysphagia (n = 1). The median LOS for the 8 patients who required extended monitoring prior to discharge was 1585 minutes (IQR 1423-1713 minutes). Overall pathway compliance with included process measures was 85.6%. The median number of ERAS process elements delivered to each patient was 18. There was no strong association between LOS and number of ERAS process elements provided (Pearson's r = -0.20). Twelve percent of the cohort was opioid tolerant on the day of surgery. There were no significant differences between total intraoperatively or postanesthesia care unit-administered opioid, or LOS, between opioid-tolerant and opioid-naïve patients. There were no complications requiring readmission.CONCLUSIONSAn ERAS pathway for anterior cervical spine surgery facilitates safe, prompt discharge. The ERAS pathway was associated with minimal complications, and no readmissions within 90 days of surgery. Pain and respiratory compromise were both linked with extended LOS in this cohort. Further prospective studies are needed to confirm the potential benefits of ERAS for anterior cervical spine surgery, including longer-term complications, cost, and functional outcomes.

Perception of Robotics and Navigation by Spine Fellows and Early Attendings: The Impact of These Technologies on Their Training and Practice.

BACKGROUND: There is scant data on the role that robotics and navigation play in spine surgery training and practice of early attendings. This study aimed to assess the impact of navigation and robotics on spine surgery training and practice. METHODS: A survey gathering information on utilization of navigation and robotics in training and practice was administered to trainees and early attendings. RESULTS: A total of 51 surveys were returned completed: 71% were attendings (average practice years: 2), 29% were trainees. During training, 22% were exposed to only fluoroscopy, 75% were exposed to navigation, 51% were exposed to robotics, and 40% were exposed to both navigation and robotics. In our sample, 87% and 61% of respondents who had exposure to navigation and robotics, respectively, felt that it had a positive impact on their training. In practice, 28% utilized only fluoroscopy, 69% utilized navigation, 30% utilized robotics, and 28% utilized both navigation and robotics. The top 3 reasons behind positive impact on training and practice were: 1) increased screw accuracy, 2) exposure to upcoming technology, and 3) less radiation exposure. The top 3 reasons behind negative impact were: 1) compromises training to independently place screws, 2) time and personnel requirements, and 3) concerns about availing it in practice. In sum, 76% of attendings felt that they will be utilizing more navigation and robotics in 5 years' time. CONCLUSIONS: Navigation and robotics have a perceivably positive impact on training and are increasingly being incorporated into practice. However, associated concerns demand spine surgeons to be thoughtful about how they integrate these technologies moving forward.

Chat Generative Pretraining Transformer Answers Patient-focused Questions in Cervical Spine Surgery.

STUDY DESIGN: Review of Chat Generative Pretraining Transformer (ChatGPT) outputs to select patient-focused questions. OBJECTIVE: We aimed to examine the quality of ChatGPT responses to cervical spine questions. BACKGROUND: Artificial intelligence and its utilization to improve patient experience across medicine is seeing remarkable growth. One such usage is patient education. For the first time on a large scale, patients can ask targeted questions and receive similarly targeted answers. Although patients may use these resources to assist in decision-making, there still exists little data regarding their accuracy, especially within orthopedic surgery and more specifically spine surgery. METHODS: We compiled 9 frequently asked questions cervical spine surgeons receive in the clinic to test ChatGPT's version 3.5 ability to answer a nuanced topic. Responses were reviewed by 2 independent reviewers on a Likert Scale for the accuracy of information presented (0-5 points), appropriateness in giving a specific answer (0-3 points), and readability for a layperson (0-2 points). Readability was assessed through the Flesh-Kincaid grade level analysis for the original prompt and for a second prompt asking for rephrasing at the sixth-grade reading level. RESULTS: On average, ChatGPT's responses scored a 7.1/10. Accuracy was rated on average a 4.1/5. Appropriateness was 1.8/3. Readability was a 1.2/2. Readability was determined to be at the 13.5 grade level originally and at the 11.2 grade level after prompting. CONCLUSIONS: ChatGPT has the capacity to be a powerful means for patients to gain important and specific information regarding their pathologies and surgical options. These responses are limited in their accuracy, and we, in addition, noted readability is not optimal for the average patient. Despite these limitations in ChatGPT's capability to answer these nuanced questions, the technology is impressive, and surgeons should be aware patients will likely increasingly rely on it.

Hypoglossal and Glossopharyngeal Nerve Palsy After Anterior Cervical Decompression and Fusion: A Case Report.

CASE: A 69-year-old man underwent a C3-4 anterior cervical discectomy and fusion and developed postoperative hypoglossal and glossopharyngeal palsies that resolved with symptomatic treatment. CONCLUSION: Cranial nerve palsy is a rare and possibly under-reported injury after higher-level cervical spine surgery. Conscientious positioning and awareness of these nerves during surgical exposure are crucial to minimizing cranial nerve palsies. Proper workup to identify these palsies and differentiate them from other complications is necessary to guide proper treatment.

Isolated Decompression for Degenerative Spondylolisthesis is Less Costly than Fusion Even with High Revision Rates.

BACKGROUND CONTEXT: Isolated decompression and decompression with instrumented fusion are accepted surgical treatments for lumbar spondylolisthesis. Although isolated decompression is a less costly solution with similar patient-reported outcomes, it is associated with higher rates of re-operation than primary fusion. PURPOSE: To determine the costs associated with primary decompression, primary fusion, and decompression and fusion for degenerative spondylolisthesis. We further sought to establish at what revision rate is primary decompression still a less costly surgical treatment for degenerative lumbar spondylolisthesis. STUDY DESIGN/SETTING: A retrospective database study of the Medicare Provider Analysis and Review (MEDPAR) limited data set. PATIENT SAMPLE: Patients who underwent single-level fusion or decompression for degenerative spondylolisthesis. OUTCOME MEASURES: Cost of surgical care. METHODS: All inpatient stays that underwent surgery for single-level lumbar/lumbosacral degenerative spondylolisthesis in the 2019 calendar year (n=6,653) were queried from the MEDPAR limited data set. Patients were stratified into three cohorts: primary decompression (n=300), primary fusion (n=5,757), and revision fusion (n=566). Univariate analysis was conducted to determine cost differences between these groups and results were confirmed with multivariable regression. An economic analysis was then done to determine at what revision rate would primary decompression still be a less costly treatment choice. RESULTS: On univariate analysis, the cost of primary single-level decompression for spondylolisthesis was $14,690±9,484, the cost of primary single-level fusion was $26,376±11,967, and revision fusion was $26,686±11,309 (p<0.001). On multivariate analysis, primary fusion was associated with an increased cost of $3,751, and revision fusion was associated with increased cost of $7,502 (95%CI: 2,990-4,512, p<0.001). Economic analysis found that a revision rate less than or equal to 43.8% would still result in primary decompression being less costly for a practice than primary fusion for all patients. CONCLUSIONS: Isolated decompression for degenerative lumbar spondylolisthesis is a less costly treatment choice even with rates of revision fusion as high as 43.8%. This was true even with an assumed revision rate of 0% after primary fusion. This study solely looks at cost data, however, and many patients may still benefit from primary fusion when appropriately indicated.

Comparison of the Safety of Inpatient Versus Outpatient Lumbar Fusion : A Systematic Review and Meta-Analysis.

STUDY DESIGN: Systematic Review and Meta-analysis. OBJECTIVE: The objective of this study is to synthesize the early data regarding and analyze the safety profile of outpatient lumbar fusion. SUMMARY OF BACKGROUND DATA: Performing lumbar fusion in an outpatient or ambulatory setting is becoming an increasingly employed strategy to provide effective value-based care. As this is an emerging option for surgeons to employ in their practices, the data is still in its infancy. METHODS: This study was conducted using the Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines. Studies that described outcomes of inpatient and outpatient lumbar fusion cohorts were searched from PubMed, Medline, The Cochrane Library, and Embase. Rates of individual medical and surgical complications, readmission, and reoperation were collected when applicable. Patient-reported outcomes (PROMs) were additionally collected if reported. Individual pooled comparative meta-analysis was performed for outcomes of medical complications, surgical complications, readmission, and reoperation. PROMs were reviewed and qualitatively reported. RESULTS: The search yielded 14 publications that compared outpatient and inpatient cohorts with a total of 75,627 patients. Odds of readmission demonstrated no significant difference between outpatient and inpatient cohorts [OR=0.94 (0.81-1.11)]. Revision surgery similarly was no different between the cohorts [OR=0.81 (0.57-1.15)]. Pooled medical and surgical complications demonstrated significantly decreased odds for outpatient cohorts compared with inpatient cohorts [OR=0.58 (0.34-0.50), OR=0.41 (0.50-0.68), respectively]. PROM measures were largely the same between the cohorts when reported, with few studies showing better ODI and VAS Leg outcomes among outpatient cohorts compared with inpatient cohorts. CONCLUSION: Preliminary data regarding the safety of outpatient lumbar fusion demonstrates a favorable safety profile in appropriately selected patients, with PROMs remaining comparable in this setting. There is no data in the form of prospective and randomized trials which is necessary to definitively change practice.

Postoperative racial disparities following spine surgery are less pronounced in the outpatient setting.

BACKGROUND CONTEXT: Racial disparities in spine surgery have been thoroughly documented in the inpatient (IP) setting. However, despite an increasing proportion of procedures being performed as same-day surgeries, whether similar differences have developed in the outpatient (OP) setting remains to be elucidated. PURPOSE: This study aimed to investigate racial differences in postoperative outcomes between Black and White patients following OP and IP lumbar and cervical spine surgery. STUDY DESIGN/SETTING: Retrospective cohort study. PATIENT SAMPLE: Patients who underwent IP or OP microdiscectomy, laminectomy, anterior cervical discectomy and fusion (ACDF), or cervical disc replacement (CDR) between 2017 and 2021. OUTCOME MEASURES: Thirty-day rates of serious and minor adverse events, readmission, reoperation, non-home discharge, and mortality. METHODS: A retrospective review of patients who underwent IP or OP microdiscectomy, laminectomy, anterior cervical discectomy and fusion (ACDF), or cervical disc replacement (CDR) between 2017 and 2021 was conducted using the National Surgical Quality Improvement Program (NSQIP) database. Disparities between Black and White patients in (1) adverse event rates, (2) readmission rates, (3) reoperation rates, (4) non-home discharge rates, (5) mortality rates, (6) operative times, and (7) hospital LOS between Black and White patients were measured and compared between IP and OP surgical settings. Multivariable logistic regression analyses were used to adjust for potential effects of baseline demographic and clinical differences. RESULTS: Of 81,696 total surgeries, 49,351 (60.4%) were performed as IP and 32,345 (39.6%) were performed as OP procedures. White patients accounted for a greater proportion of IP (88.2% vs. 11.8%) and OP (92.7% vs. 7.3%) procedures than Black patients. Following IP surgery, Black patients experienced greater odds of serious (OR 1.214, 95% CI 1.077-1.370, p=.002) and minor adverse events (OR 1.377, 95% CI 1.113-1.705, p=.003), readmission (OR 1.284, 95% CI 1.130-1.459, p<.001), reoperation (OR 1.194, 95% CI 1.013-1.407, p=.035), and non-home discharge (OR 2.304, 95% CI 2.101-2.528, p<.001) after baseline adjustment. Disparities were less prominent in the OP setting, as Black patients exhibited greater odds of readmission (OR 1.341, 95% CI 1.036-1.735, p=0.026) but were no more likely than White patients to experience adverse events, reoperation, individual complications, non-home discharge, or death (p>.050 for all). CONCLUSIONS: Racial inequality in postoperative complications following spine surgery is evident, however disparities in complication rates are relatively less following OP compared to IP procedures. Further work may be beneficial in elucidating the causes of these differences to better understand and mitigate overall racial disparities within the inpatient setting. These decreased differences may also provide promising indication that progress towards reducing inequality is possible as spine care transitions to the OP setting.

Erector Spinae Plane Block Reduces Immediate Postoperative Pain and Opioid Demand After Minimally Invasive Transforaminal Lumbar Interbody Fusion.

STUDY DESIGN: Matched cohort comparison. OBJECTIVE: To determine perioperative outcomes of erector spinae plane (ESP) block for minimally invasive transforaminal lumbar interbody fusion (MI-TLIF). SUMMARY OF BACKGROUND DATA: There is a paucity of data on the impact of lumbar ESP block on perioperative outcomes and its safety in MI-TLIF. MATERIALS AND METHODS: Patients who underwent 1-level MI-TLIF and received the ESP block (group E ) were included. An age and sex-matched control group was selected from a historical cohort that received the standard-of-care (group NE). The primary outcome of this study was 24-hour opioid consumption in morphine milligram equivalents. Secondary outcomes were pain severity measured by a numeric rating scale, opioid-related side effects, and hospital length of stay. Outcomes were compared between the two groups. RESULTS: Ninety-eight and 55 patients were included in the E and NE groups, respectively. There were no significant differences between the two cohorts in patient demographics. Group E had lower 24-hour postoperative opioid consumption ( P = 0.117, not significant), reduced opioid consumption on a postoperative day (POD) 0 ( P = 0.016), and lower first pain scores postsurgery ( P < 0.001). Group E had lower intraoperative opioid requirements ( P < 0.001), and significantly lower average numeric rating scale pain scores on POD 0 ( P = 0.034). Group E reported fewer opioid-related side effects as compared with group NE, although this was not statistically significant. The average highest postoperative pain score within 3 hours postprocedurally was 6.9 and 7.7 in the E and NE cohorts, respectively ( P = 0.029). The median length of stay was comparable between groups with the majority of patients in both groups being discharged on POD 1. CONCLUSIONS: In our retrospective matched cohort, ESP blocks resulted in reduced opioid consumption and decreased pain scores on POD 0 in patients undergoing MI-TLIF. LEVEL OF EVIDENCE: Level 3.

Feasibility of Saphenous Nerve Somatosensory-Evoked Potential Intraoperative Monitoring During Lumbar Spine Surgery: Early Results.

STUDY DESIGN: Retrospective review. OBJECTIVE: Assess the feasibility of saphenous nerve somatosensory evoked potentials (SN-SSEP) monitoring in lumbar spine surgeries. BACKGROUND CONTEXT: SN-SSEPs have been proposed for detecting lumbar plexus and femoral nerve injury during lateral lumbar surgery where tibial nerve (TN) SSEPs alone are insufficient. SN-SSEPs may also be useful in other types of lumbar surgery, as stimulation of SN below the knee derives solely from the L4 root and provides a means of L4 monitoring, whereas TN-SSEPs often do not detect single nerve root injury. The feasibility of routine SN-SSEP monitoring has not been established. METHODS: A total of 563 consecutive cases using both TN-SSEP and SN-SSEP monitoring were included. Anesthesia was at the discretion of the anesthesiologist, using an inhalant in 97.7% of procedures. SN stimulation was performed using 13 mm needle electrodes placed below the knee using 200-400 µsec pulses at 15 to 100 mA. Adjustments to stimulation parameters were made by the neurophysiology technician while obtaining baselines. Data were graded retrospectively for monitorability and cortical response amplitudes were measured by two independent reviewers. RESULTS: Ninety-eight percent of TN-SSEPs and 92.5% of SN-SSEPs were monitorable at baseline, with a mean response amplitude of 1.35 µV for TN-SSEPs and 0.71 µV for SN-SSEPs. A significant difference between the stimulation parameters used to obtain reproducible TN and SN-SSEPs at baseline was observed, with SN-SSEPs requiring greater stimulation intensities. Body mass index is not associated with baseline monitorability. Out of 20 signal changes observed, 11 involved SN, while TN-SSEPs were unaffected. CONCLUSION: With adjustments to stimulation parameters, SN-SSEP monitoring is feasible within a large clinical cohort without modifications to the anesthetic plan. Incorporating SN into standard intraoperative neurophysiological monitoring protocols for lumbar spine procedures may expand the role of SSEP monitoring to include detecting injury to the lumbar plexus. LEVEL OF EVIDENCE: 3.

Trends in Indications and Contraindications for Cervical Disk Arthroplasty from 2009 to 2019.

STUDY DESIGN: Cross-sectional study. OBJECTIVE: Assess trends of indications and contraindications for the use of Cervical Disk Arthroplasty (CDA). SUMMARY OF BACKGROUND DATA: As spine surgeons become more familiar with CDA, there have been expansions in indications. METHODS: The Medicare Provider Analysis and Review Limited Data Sets for 2009, 2014, and 2019 were utilized. Patients undergoing elective CDA were included. Diagnosis for index surgery and "contraindications" as defined by original CDA Investigative Device Exemption (IDE) criteria were assessed. Variables were identified by the International Classification of Diseases (ICD)-9 or ICD-10 diagnosis and procedural codes. RESULTS: A total of 1067 elective CDA patients were included. There were 230 patients in 2009, 300 patients in 2014, and 537 patients in 2019. The proportion of patients aged >65 increased from 35% to 51% (P<0.001). Incidence of CDA for radiculopathy increased from 57% to 69% (P<0.001), myelopathy increased from 23% to 78% (P<0.001), and spondylosis without radiculopathy or myelopathy decreased from 19% to 3% (P<0.001). There were increased incidences of ankylosing spondylitis (0.4% to 2.8%, P=0.007), long-term steroid use (1% to 2%, P=0.039), morbid obesity (2% to 6%, P=0.019), and osteoporosis (1% to 5%, P=0.014). The incidence of hybrid CDA and anterior cervical discectomy and fusion (ACDF) decreased from 28% to 23% (P=0.007). CONCLUSION: From 2009 to 2019, the number of CDA performed in older patients increased. An increase in the use of CDA for the treatment of myelopathy and radiculopathy and a decrease in the treatment of isolated cervical spondylosis was observed. The proportion of CDA performed in patients with original IDE trial "contraindications" increased. Further research into the efficacy of CDA for patients with contraindications is warranted.