Minimally invasive spine surgery is primed for innovation and development. As imaging and navigations modalities continue to develop, their impact on clinical outcomes and patient quality of life is expected to be substantial, marking a significant step forward in neurosurgical practice. By combining these advanced technologies with minimally invasive surgical approaches and adjuvant therapies, we are bound to significantly improve patient outcomes, minimize neurological deficits, and enhance the overall quality of life for patients with spinal tumors.

An erratum was issued for: In vivo Mouse Model of Spinal Implant Infection. The Authors section was updated from:

BACKGROUND CONTEXT Driven by an attempt to reduce health care expenditures as well as patient proportion, a growing proportion of cervical spine surgery is performed in ambulatory surgery centers. Indeed, there has been a 60% increase in the number of ambulatory surgery centers since 2010. Cervical disc replacement (CDR) has been increasingly performed in the outpatient setting in recent years. Patients undergoing CDR are more likely to be younger with a favorable comorbidity profile compared to those undergoing anterior cervical discectomy and fusion. It is important to avoid prolonged length of stay or unplanned readmission; these adverse outcomes are associated with increased morbidity and cost. Prediction of prolonged hospitalization or short-term readmission would thus be of utility. PURPOSE We aim to develop an algorithm for prediction of prolonged hospitalization or unplanned short-term readmission after outpatient CDR. We additionally aim to identify novel features important for model performance. STUDY DESIGN/SETTING Retrospective, cohort study. PATIENT SAMPLE Adult patients who underwent outpatient CDR between 2012 and 2020 in the American College of Surgeons National Surgical Quality Improvement Program (ACS-NSQIP) Registry. OUTCOME MEASURES The primary outcome was prolonged admission greater than one night or readmission within three days after outpatient CDR. METHODS We built logistic regression and four machine learning models that span different classes of modeling techniques: XGBoost, AdaBoost, gradient boosting, and random forest. Discrimination was assessed using the area under the receiver operating characteristic curve (AUROC). Calibration was assessed using the calibration slope, calibration intercept, and Brier score. Utilizing a partial dependence function, we ranked the contribution of the included variables to the prediction of prolonged admission or unplanned readmission. RESULTS A total of 2,033 patients met inclusion criteria. Of these patients who underwent outpatient CDR, 117 patients (5.8%) patients required admission greater than one night and eight (0.4%) were readmitted within three days after surgery. The random forest model was the best-performing model of all tested models with an AUROC of 0.707 + 0.061. The model was well-calibrated with a calibration slope of 1.135, calibration intercept of -0.011, and Brier score of 0.056. The features most important for model performance include: female sex, American Society of Anesthesiology Class >3, body mass index, chronic obstructive pulmonary disease, diabetes mellitus, hypertension, steroid use, number of levels operated on, and operative time. CONCLUSIONS We report a random forest algorithm for prediction of prolonged admission or unplanned short-term readmission after outpatient CDR. This algorithm is well-calibrated and displays good discrimination with an AUROC of 0.707. CDR is well-positioned for the ambulatory setting. While numerous studies have shown that ambulatory CDR is associated with excellent outcomes, patient selection is key. Accurate prediction of which patients are at high risk of unplanned readmission or extended admission may aid with appropriate patient selection for outpatient versus inpatient surgery, decreasing cost and morbidity. Modifiable risk factors such as diabetes, obesity, and hypertension may be optimized prior to outpatient CDR to reduce the likelihood of these adverse outcomes. FDA Device/Drug Status This abstract does not discuss or include any applicable devices or drugs.

Posterior cervical foraminotomy is a commonly performed procedure to address cervical radiculopathy through direct decompression of the neural foramen by partially resecting the dorsal aspect of the facet joint. The procedure is an alternative to anterior cervical approaches such as anterior cervical discectomy and fusion and cervical disc arthroplasty, which require complete discectomy to address foraminal stenosis that cause cervical radiculopathy. The procedure has evolved from open to minimally invasive techniques including endoscopic methods, which has recently increased in interest by spine surgeons. This review discusses the currently existing endoscopic techniques for cervical posterior foraminotomy and synthesizes the existing literature.

Endoscopic spine surgery has recently grown in popularity due to the potential benefits of reduced pain and faster recovery time as compared to open surgery. Biportal spinal endoscopy has been successfully applied to lumbar disc herniations and lumbar spinal stenosis. Obesity is associated with increased risk of complications in spine surgery. Few prior studies have investigated the impact of obesity and associated medical comorbidities with biportal spinal endoscopy. This study was a prospectively collected, retrospectively analyzed comparative cohort design. Patients were divided into cohorts of normal body weight (Bone Mass Index (BMI)18.0–24.9), overweight (BMI 25.0–29.9) and obese (BMI > 30.0) as defined by the World Health Organization (WHO). Patients underwent biportal spinal endoscopy by a single surgeon at a single institution for treatment of lumbar disc herniations and lumbar spinal stenosis. Demographic data, surgical complications, and patient-reported outcomes were analyzed. Statistics were calculated amongst treatment groups using analysis of variance and chi square where appropriate. Statistical significance was determined as p < 0.05. Eighty-four patients were followed. 26 (30.1

BACKGROUND CONTEXT: Mortality in patients with spinal epidural abscess (SEA) remains high. Accurate prediction of patient-specific prognosis in SEA can improve patient counseling as well as guide management decisions. There are no externally validated studies predicting shortterm mortality in patients with SEA. PURPOSE: The purpose of this study was to externally validate the Skeletal Oncology Research Group (SORG) stochastic gradient boosting algorithm for prediction of in-hospital and 90-day postdischarge mortality in SEA. STUDY DESIGN/SETTING: Retrospective, case-control study at a tertiary care academic medical center from 2003 to 2021. PATIENT SAMPLE: Adult patients admitted for radiologically confirmed diagnosis of SEA who did not initiate treatment at an outside institution. OUTCOME MEASURES: In-hospital and 90-day postdischarge mortality. METHODS: We tested the SORG stochastic gradient boosting algorithm on an independent validation cohort. We assessed its performance with discrimination, calibration, decision curve analysis, and overall performance. RESULTS: A total of 212 patients met inclusion criteria, with a short-term mortality rate of 10.4%. The area under the receiver operating characteristic curve (AUROC) of the SORG algorithm when tested on the full validation cohort was 0.82, the calibration intercept was -0.08, the calibration slope was 0.96, and the Brier score was 0.09. CONCLUSIONS: With a contemporaneous and geographically distinct independent cohort, we report successful external validation of a machine learning algorithm for prediction of in-hospital and 90-day postdischarge mortality in SEA. (c) 2023 Elsevier Inc. All rights reserved.

An erratum was issued for: In vivo Mouse Model of Spinal Implant Infection. The Authors section was updated from: Benjamin V. Kelley1 Stephen D. Zoller1 Danielle Greig1 Kellyn Hori1 Nicolas Cevallos1 Chad Ishmael1 Peter Hsiue1 Rishi Trikha1 Troy Sekimura2 Thomas Olson2 Ameen Chaudry2 Michael M. Le2 Anthony A. Scaduto1 Kevin P. Francis1 Nicholas M. Bernthal11Department of Orthopaedic Surgery, University of California Los Angeles 2David Geffen School of Medicine, University of California Los Angeles to: Benjamin V. Kelley1 Christopher Hamad1 Stephen D. Zoller1 Danielle Greig1 Zeinab Mamouei1 Rene Chun1 Kellyn Hori1 Nicolas Cevallos1 Chad Ishmael1 Peter Hsiue1 Rishi Trikha1 Troy Sekimura2 Brandon Gettleman3 Autreen Golzar2 Adrian Lin2 Thomas Olson2 Ameen Chaudry2 Michael M. Le2 Anthony A. Scaduto1 Kevin P. Francis1 Nicholas M. Bernthal11Department of Orthopaedic Surgery, University of California Los Angeles 2David Geffen School of Medicine, University of California Los Angeles 3University of South Carolina School of Medicine, University of South Carolina.

BACKGROUND:Biportal spinal endoscopy is increasingly utilized for lumbar disc herniations and lumbar stenosis. The objective was to investigate the safety and effectiveness of the technique in the outpatient vs inpatient setting.METHODS:This is a comparative study of consecutive patients who underwent biportal spinal endoscopy by a single surgeon at a single institution. Demographics, surgical complications, and patient-reported outcomes were prospectively collected and retrospectively analyzed. Statistics were calculated among treatment groups using unpaired t test and χ 2 analysis where appropriate. Statistical significance was determined as P < 0.05.RESULTS:Eighty-four patients were included, 58 (69.0%) as outpatient, 26 (31.0%) as inpatient. Mean follow-up was 7.5 months. Statistically significant differences in age, American Society of Anesthesiologists classification, and Charleston Comorbidity Index scores were reported between cohorts, with younger and healthier patients undergoing outpatient surgery (P < 0.0001). Outpatients were more likely to have discectomies while inpatients were more likely to have decompressions for stenosis. No significant differences in postoperative complications were found between groups.Both cohorts demonstrated significant improvement in visual analog scale (VAS) back and leg pain scores and Oswestry Disability Index scores (P < 0.001). Outpatients had significantly lower postoperative VAS back pain (P = 0.001) and Oswestry Disability Index scores (P = 0.004) at 5-8 weeks compared with inpatients, but there was no significant difference for VAS leg pain scores at all time points between the cohorts.CONCLUSIONS:Early results demonstrate that biportal spinal endoscopy can safely and effectively be performed in both inpatient and outpatient settings.CLINICAL RELEVANCE:Outpatient biportal spinal endoscopy can be performed successfully in well selected patients, which may reduce the financial burden of spine surgery to the U.S. healthcare system.LEVEL OF EVIDENCE: 3:

BACKGROUND Assessing academic productivity allows academic departments to identify the strengths of their scholarly contribution and provides an opportunity to evaluate areas for improvement. AIM To provide objective benchmarks for departments seeking to enhance academic productivity and identify those with significant improvement in recent past. METHODS Our study retrospectively analyzed a cohort of orthopaedic faculty at United States-based academic orthopaedic programs. 5502 full-time orthopaedic faculty representing 178 programs were included in analysis. Variables included for analysis were National Institutes of Health funding (2014-2018), leadership positions in orthopaedic societies (2018), editorial board positions of top orthopaedic journals (2018), total number of publications and Hirsch-index. A weighted algorithm was used to calculate a cumulative score for each academic program. This study was performed at a large, United States medical school. RESULTS All 178 programs included in analysis were evaluated using the comprehensive weighted algorithm. The five institutions with the highest cumulative score, in decreasing order, were: Washington University in St. Louis, the Hospital for Special Surgery, Sidney Kimmel Medical College (SKMC) at Thomas Jefferson University, the University of California, San Francisco (UCSF) and Massachusetts General Hospital (MGH)/Brigham and Women’s/Harvard. The five institutions with the highest score per capita, in decreasing order, were: Mayo Clinic (Rochester), Washington University in St. Louis, Rush University, Virginia Commonwealth University (VCU) and MGH/Brigham and Women’s/Harvard. The five academic programs that had the largest improvement in cumulative score from 2013 to 2018, in decreasing order, were: VCU, SKMC at Thomas Jefferson University, UCSF, MGH/Brigham and Women’s/Harvard, and Brown University. CONCLUSION This algorithm can provide orthopaedic departments a means to assess academic productivity, monitor progress, and identify areas for improvement as they seek to expand their academic contributions to the orthopaedic community.

Renal disease including chronic renal disease and end-stage renal disease has been associated with the development of primary glenohumeral osteoarthritis. However, little is known about how renal disease affects outcomes after shoulder arthroplasty. Thus, the purpose of this study was to evaluate the impact of renal disease on outcomes of shoulder arthroplasty for glenohumeral osteoarthritis. This was a retrospective review using the Nationwide Readmissions Database. Using International Classification of Diseases, 9th Revision, codes, patients who underwent shoulder arthroplasty (including total shoulder arthroplasty and reverse total shoulder arthroplasty) for primary glenohumeral osteoarthritis were identified. These patients were divided into 3 groups: no renal disease, predialysis chronic renal disease (including stages 1-5), and end-stage renal disease. Primary outcomes of interest included the risk of complications during index hospitalization as well as within 90 days of index surgery. Secondary outcomes included index hospitalization length of stay, cost, and discharge location. From 2010 to 2014, a total of 29,336 patients underwent shoulder arthroplasty for glenohumeral osteoarthritis. Of these 29,336, 27,928 (95.2%) patients had no renal disease, 1355 (4.6%) had predialysis chronic renal disease, and 53 (0.2%) patients had end-stage renal disease. Compared with patients with no renal disease, both predialysis chronic renal disease and end-stage renal disease patients had an increased risk of receiving blood transfusions (odds ratio [OR] = 2.04, P < .0001, and 5.37, P = .04, respectively) and experiencing any postoperative complication during the index hospitalization (OR = 2.31, P < .0001, and 3.94, P = .003, respectively). Specifically, predialysis chronic renal disease patients were at an increased risk for cardiac (OR = 1.96, P < .0001) and respiratory (OR = 1.55, P < .0001) complications as well as acute renal failure (OR = 14.70, P < .0001) postoperatively. End-stage renal disease patients were at an increased risk for cardiac (OR = 3.87, P = .003) complications as well as acute renal failure (OR = 10.35, P = .002) postoperatively. Within 90 days, end-stage renal disease patients had an increased risk of hospital readmission (OR = 8.01, P < .0001), dislocation (OR = 8.70, P = .039), and surgical site infection (OR = 19.06, P = .001). Finally, compared with patients with no renal disease, predialysis chronic renal disease and end-stage renal disease patients both had increased hospital length of stay and cost; predialysis chronic renal disease patients had an increased risk of discharge to a skilled nursing facility (OR = 1.39, P = .039). This retrospective cohort study demonstrates that even predialysis chronic renal disease patients have worse outcomes compared with patients with no renal disease after shoulder arthroplasty for glenohumeral osteoarthritis. These findings serve to highlight the importance of close perioperative monitoring to prevent complications in a potentially overlooked patient population.

Background:Evidence suggests the renin-angiotensin system (RAS) plays key immunomodulatory roles. In particular, angiotensin-converting enzyme (ACE) has been shown to play a role in antimicrobial host defense. ACE inhibitors (ACEi) and angiotensin receptor blockers (ARB) are some of the most commonly prescribed medications, especially in patients undergoing invasive surgery. Thus, the current study assessed the immunomodulatory effect of RAS-modulation in a preclinical model of implant infection. Methods:In vitroantimicrobial effects of ACEi and ARBs were first assessed. C57BL/6J mice subsequently received either an ACEi (lisinopril; 16 mg/kg/day), an ARB (losartan; 30 mg/kg/day), or no treatment. Conditioned mice blood was then utilized to quantify respiratory burst function as well asStaphylococcus aureusXen36 burdenex vivoin each treatment group.S. aureusinfectious burden for each treatment group was then assessedin vivousing a validated mouse model of implant infection. Real-time quantitation of infectious burden via bioluminescent imaging over the course of 28 days post-procedure was assessed. Host response via monocyte and neutrophil infiltration within paraspinal and spleen tissue was quantified by immunohistochemistry for F4/80 and myeloperoxidase, respectively. Results:Blood from mice treated with an ACEi demonstrated a decreased ability to eradicate bacteria when mixed with Xen36 as significantly higher levels of colony forming units (CFU) and biofilm formation was appreciatedex vivo(p< 0.05). Mice treated with an ACEi showed a higher infection burdenin vivoat all times (p< 0.05) and significantly higher CFUs of bacteria on both implant and paraspinal tissue at the time of sacrifice (p< 0.05 for each comparison). There was also significantly decreased infiltration and respiratory burst function of immune effector cells in the ACEi group (p< 0.05). Conclusion:ACEi, but not ARB, treatment resulted in increasedS. aureusburden and impaired immune response in a preclinical model of implant infection. These results suggest that perioperative ACEi use may represent a previously unappreciated risk factor for surgical site infection. Given the relative interchangeability of ACEi and ARB from a cardiovascular standpoint, this risk factor may be modifiable.

Spine implant infections portend poor outcomes as diagnosis is challenging and surgical eradication is at odds with mechanical spinal stability. The purpose of this method is to describe a novel mouse model of spinal implant infection (SII) that was created to provide an inexpensive, rapid, and accurate in vivo tool to test potential therapeutics and treatment strategies for spinal implant infections. In this method, we present a model of posterior-approach spinal surgery in which a stainless-steel k-wire is transfixed into the L4 spinous process of 12-week old C57BL/6J wild-type mice and inoculated with 1 x 103 CFU of a bioluminescent strain of Staphylococcus aureus Xen36 bacteria. Mice are then longitudinally imaged for bioluminescence in vivo on post-operative days 0, 1, 3, 5, 7, 10, 14, 18, 21, 25, 28, and 35. Bioluminescence imaging (BLI) signals from a standardized field of view are quantified to measure in vivo bacterial burden. To quantify bacteria adhering to implants and peri-implant tissue, mice are euthanized and the implant and surrounding soft tissue are harvested. Bacteria are detached from the implant by sonication, cultured overnight and then colony forming units (CFUs) are counted. The results acquired from this method include longitudinal bacterial counts as measured by in vivo S. aureus bioluminescence (mean maximum flux) and CFU counts following euthanasia. While prior animal models of instrumented spine infection have involved invasive, ex vivo tissue analysis, the mouse model of SII presented in this paper leverages noninvasive, real time in vivo optical imaging of bioluminescent bacteria to replace static tissue study. Applications of the model are broad and may include utilizing alternative bioluminescent bacterial strains, incorporating other types of genetically engineered mice to contemporaneously study host immune response, and evaluating current or investigating new diagnostic and therapeutic modalities such as antibiotics or implant coatings.