Anatomic Parameters for Diagnosing Congenital Lumbar Stenosis Based on Computed Tomography of 1,000 Patients.

INTRODUCTION: Quantitative parameters for diagnosis of congenital lumbar stenosis (CLS) have yet to be universally accepted. This study establishes parameters for CLS using CT, assessing the influences of patient sex, race, ethnicity, and anthropometric characteristics. METHODS: Interpedicular distance (IPD), pedicle length, canal diameter, and canal area were measured using 1,000 patients between 18 and 35 years of age who were without spinal pathology. RESULTS: Irrespective of disk level, threshold values for CLS were 16.1 mm for IPD, 3.9 mm for pedicle length, 11.5 mm for canal diameter, and 142.5 mm2 for canal area. Notable differences based on patient sex were observed, with men demonstrating larger CLS threshold values with respect to IPD and canal area across all vertebral levels from L1 to L5. Based on patient anthropometric factors, no strong or moderate associations were observed between any spinal measurement and patient height, weight, or body mass index across all levels from L1 to L5. However, notable differences were observed based on patient race and ethnicity from L1 to L5. Asian patients demonstrated the largest pedicle lengths, followed by White, Hispanic, and Black patients in descending order. White patients demonstrated the largest IPD, canal AP diameter, and canal area, followed by Asian, Hispanic, and Black patients in descending order. Black patients demonstrated the smallest values across all anatomic measurements relative to Asian, White, and Hispanic patients. CONCLUSION: This study reports 25,000 measurements of lumbar central canal dimensions to establish quantitative thresholds for the diagnosis of CLS. Although not influenced by patient height, weight, or body mass index as one might intuit, canal dimensions were influenced by patient sex, race, and ethnicity. These findings may help explain differences in predisposition or prevalence of lumbar nerve root compression among patients of different races, which can be important when considering rates of surgery and access to care.

Disparities in Surgical Intervention and Health-Related Quality of Life Among Racial/Ethnic Groups With Degenerative Lumbar Spondylolisthesis.

BACKGROUND AND OBJECTIVES: Racial and socioeconomic disparities in spine surgery for degenerative lumbar spondylolisthesis persist in the United States, potentially contributing to unequal health-related quality of life (HRQoL) outcomes. This is important as lumbar spondylolisthesis is one of the most common causes of surgical low back pain, and low back pain is the largest disabler of individuals worldwide. Our objective was to assess the relationship between race, socioeconomic factors, treatment utilization, and outcomes in patients with lumbar spondylolisthesis. METHODS: This cohort study analyzed prospectively collected data from 9941 patients diagnosed with lumbar spondylolisthesis between 2015 and 2020 at 5 academic hospitals. Exposures were race, socioeconomic status, health coverage, and HRQoL measures. Main outcomes and measures included treatment utilization rates between racial groups and the association between race and treatment outcomes using logistic regression, adjusting for patient characteristics, socioeconomic status, health coverage, and HRQoL measures. RESULTS: Of the 9941 patients included (mean [SD] age, 67.37 [12.40] years; 63% female; 1101 [11.1%] Black, Indigenous, and People of Color [BIPOC]), BIPOC patients were significantly less likely to use surgery than White patients (odds ratio [OR] = 0.68; 95% CI, 0.62-0.75). Furthermore, BIPOC race was associated with significantly lower odds of reaching the minimum clinically important difference for physical function (OR = 0.74; 95% CI, 0.60; 0.91) and pain interference (OR = 0.77; 95% CI, 0.62-0.97). Medicaid beneficiaries were significantly less likely (OR = 0.65; 95% CI, 0.46-0.92) to reach a clinically important improvement in HRQoL when accounting for race. CONCLUSION: This study found that BIPOC patients were less likely to use spine surgery for degenerative lumbar spondylolisthesis despite reporting higher pain interference, suggesting an association between race and surgical utilization. These disparities may contribute to unequal HRQoL outcomes for patients with lumbar spondylolisthesis and warrant further investigation to address and reduce treatment disparities.

Advancing equity in spine surgery: unraveling the impact of affirmative action reversal.

Affirmative action has been pivotal in addressing historical and systemic discrimination, particularly within healthcare. This paper delves into the impact of affirmative action policies on diversity in spine surgery, elucidating their critical role in fostering inclusivity and equal opportunities for individuals of underrepresented racial and ethnic groups. Historically, affirmative action has been instrumental in breaking down barriers to education and careers in medicine. Landmark cases such as Brown v. Board of Education have been influential in shaping these policies. However, the recent reversal of affirmative action poses a substantial threat to diversity in medical school admissions, potentially diminishing the presence of minority groups in spine surgery. We examine the historical foundation and transformative impact of affirmative action, focusing on key legal cases and their influence on educational and professional inclusivity. The current landscape of diversity in medical education and spine surgery highlights the role of affirmative action in cultivating an inclusive workforce. Counterarguments to affirmative action are critically evaluated, emphasizing the extensive benefits of diversity in enhancing patient care, driving research innovation, and informing policy advocacy. To counteract the adverse effects of the affirmative action reversal, we propose proactive initiatives, including targeted support for college students, medical students, residents, and practicing surgeons. These strategies are designed to ensure the recruitment and retention of a diverse workforce in spine surgery, thereby enriching patient care and advancing the field.

Artificial Intelligence Portrayals in Orthopaedic Surgery: An Analysis of Gender and Racial Diversity Using Text-to-Image Generators.

BACKGROUND: The increasing accessibility of artificial intelligence (AI) text-to-image generators offers a novel avenue for exploring societal perceptions. The present study assessed AI-generated images to examine the representation of gender and racial diversity among orthopaedic surgeons. METHODS: Five prominent text-to-image generators (DALL·E 2, Runway, Midjourney, ImagineAI, and JasperArt) were utilized to create images for the search queries "Orthopedic Surgeon," "Orthopedic Surgeon's Face," and "Portrait of an Orthopedic Surgeon." Each query produced 80 images, resulting in a total of 240 images per generator. Two independent reviewers categorized race, sex, and age in each image, with a third reviewer resolving discrepancies. Images with incomplete or multiple faces were excluded. The demographic proportions (sex, race, and age) of the AI-generated images were then compared with those of the 2018 American Academy of Orthopaedic Surgeons (AAOS) census. RESULTS: In our examination across all AI platforms, 82.8% of the images depicted surgeons as White, 12.3% as Asian, 4.1% as Black, and 0.75% as other; 94.5% of images were men; and a majority (64.4%) appeared ≥50 years old. DALL·E 2 exhibited significantly increased diversity in representation of both women and non-White surgeons compared with the AAOS census, whereas Midjourney, Runway, and ImagineAI exhibited significantly decreased representation. CONCLUSIONS: The present study highlighted distortions in AI portrayal of orthopaedic surgeon diversity, influencing public perceptions and potentially reinforcing disparities. DALL·E 2 and JasperArt show encouraging diversity, but limitations persist in other generators. Future research should explore strategies for improving AI to promote a more inclusive and accurate representation of the evolving demographics of orthopaedic surgery, mitigating biases related to race and gender. CLINICAL RELEVANCE: This study is clinically relevant as it investigates the accuracy of AI-generated images in depicting diversity among orthopaedic surgeons. The findings reveal significant discrepancies in representation by race and gender, which could impact societal perceptions and exacerbate existing disparities in health care.

You say you want to be "diverse": what are the practical steps towards increasing diversity of spine surgeons?

This article explores the critical issue of underrepresentation in spine surgery, specifically addressing racial/ethnic diversity. The paper proposes actionable strategies to enhance diversity within spine surgery through early education and outreach, intentional mentorship and sponsorship, and addressing biases in recruitment and promotion processes. It emphasizes the importance of a supportive culture within spine surgery divisions and practices, advocating for a top-down approach to inclusivity, while underscoring the necessity of continuous evaluation and adaptation of diversity initiatives. By leveraging diverse perspectives, the field of spine surgery can better serve an increasingly heterogeneous population, ultimately improving patient care and healthcare outcomes.

Social determinants of health and disparities in spine surgery: a 10-year analysis of 8,565 cases using ensemble machine learning and multilayer perceptron.

BACKGROUND CONTEXT: The influence of SDOH on spine surgery is poorly understood. Historically, researchers commonly focused on the isolated influences of race, insurance status, or income on healthcare outcomes. However, analysis of SDOH is becoming increasingly more nuanced as viewing social factors in aggregate rather than individually may offer more precise estimates of the impact of SDOH on healthcare delivery. PURPOSE: The aim of this study was to evaluate the effects of patient social history on length of stay (LOS) and readmission within 90 days following spine surgery using ensemble machine learning and multilayer perceptron. STUDY DESIGN: Retrospective chart review. PATIENT SAMPLE: 8,565 elective and emergency spine surgery cases performed from 2013 to 2023 using our institution's database of longitudinally collected electronic medical record information. OUTCOMES MEASURES: Patient LOS, discharge disposition, and rate of 90-day readmission. METHODS: Ensemble machine learning and multilayer perceptron were employed to predict LOS and readmission within 90 days following spine surgery. All other subsequent statistical analysis was performed using SPSS version 28. To further assess correlations among variables, Pearson's correlation tests and multivariate linear regression models were constructed. Independent sample t-tests, paired sample t-tests, one-way analysis of variance (ANOVA) with post-hoc Bonferroni and Tukey corrections, and Pearson's chi-squared test were applied where appropriate for analysis of continuous and categorical variables. RESULTS: Black patients demonstrated a greater LOS compared to white patients, but race and ethnicity were not significantly associated with 90-day readmission rates. Insured patients had a shorter LOS and lower readmission rates compared to non-insured patients, as did privately insured patients compared to publicly insured patients. Patients discharged home had lower LOS and lower readmission rates, compared to patients discharged to other facilities. Marriage decreased both LOS and readmission rates, underweight patients showcased increased LOS and readmission rates, and religion was shown to impact LOS and readmission rates. When utilizing patient social history, lab values, and medical history, machine learning determined the top 5 most-important variables for prediction of LOS -along with their respective feature importances-to be insurance status (0.166), religion (0.100), ICU status (0.093), antibiotic use (0.061), and case status: elective or urgent (0.055). The top 5 most-important variables for prediction of 90-day readmission-along with their respective feature importances-were insurance status (0.177), religion (0.123), discharge location (0.096), emergency case status (0.064), and history of diabetes (0.041). CONCLUSIONS: This study highlights that SDOH is influential in determining patient length of stay, discharge disposition, and likelihood of readmission following spine surgery. Machine learning was utilized to accurately predict LOS and 90-day readmission with patient medical history, lab values, and social history, as well as social history alone.

Morphometric analysis of cervical neuroforaminal dimensions from C2-T1 using computed tomography of 1,000 patients.

BACKGROUND: Race and sex differences are not consistently reported in the literature. Fundamentally, anatomical differences of cervical neuroforaminal dimensions (CNFD) amongst these groups would be important to know. PURPOSE: To establish normative radiographic morphometric measurements of CNFD and uncover the influence of patient sex, race, and ethnicity while also considering anthropometric characteristics. STUDY DESIGN: Retrospective radiographic morphometric study. PATIENT SAMPLE: A total of 1,000 patients between 18 and 35 years of age who were free of spinal pathology. OUTCOME MEASURES: Foraminal height, axial width, and area of cervical neural foramen. METHODS: Cervical CTs were reviewed to measure CNFD, defined as follows: foraminal height, axial width, and area. Statistical analyses were performed to assess associations between CNFD, and patient height, weight, sex, race, and ethnicity. RESULTS: CNFD measurements followed a bimodal distribution pattern moving caudally from C2-T1. Irrespective of disc level, cervical CNFD were as follows: left and right widths of 6.6±1.5 and 6.6±1.5 mm, heights of 9.4±2.4 and 9.4±3.2 mm, and areas of 60.0±19.5 and 60.6±20.7 mm2. Left and right foraminal width were highest at C2-C3 and lowest at C3-C4. Left and right foraminal height were highest at C7-T1 and C6-C7, respectively and lowest at C3-C4. Left and right foraminal areas were highest at C2-C3 and lowest at C3-C4. Significant differences were observed for all CNFD measurements across disc levels. CNFD did not vary based on laterality. Significant CNFD differences were observed with respect to patient sex, race, and ethnicity. Male height and area were larger compared to females. In contrast, female foraminal width was larger compared to males. The Asian cohort demonstrated the largest foraminal widths. White and Hispanic patients demonstrated the largest foraminal heights and areas. Black patients demonstrated the smallest foraminal widths, heights, and areas. Patient height and weight were only weakly correlated with CNFD measurements across all levels from C2-T1. CONCLUSIONS: This study describes 36,000 normative measurements of 12,000 foramina from C2-T1. CNFD measurements vary based on disc level, but not laterality. Contrasting left- versus right-sided neuroforamina of the same level may aid in determining the presence of unilateral stenosis. Patient sex, race, and ethnicity are associated with CNFD, while patient anthropometric factors are weakly correlated with CNFD.

Addressing the Impact of Race and Ethnicity on Musculoskeletal Spine Care in the United States.

➤ Despite being a social construct, race has an impact on outcomes in musculoskeletal spine care.➤ Race is associated with other social determinants of health that may predispose patients to worse outcomes.➤ The musculoskeletal spine literature is limited in its understanding of the causes of race-related outcome trends.➤ Efforts to mitigate race-related disparities in spine care require individual, institutional, and national initiatives.

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

INTRODUCTION: Some patients, particularly those who are socioeconomically deprived, are diagnosed with primary and/or metastatic cancer only after presenting to the emergency department. Our objective was to determine sociodemographic characteristics of patients undergoing surgery for metastatic spine disease at our institution. METHODS: This retrospective case series included patients 18 years and older who presented to the emergency department with metastatic spine disease requiring surgery. Demographics and survival data were collected. Sociodemographic characteristics were estimated using the Social Deprivation Index (SDI) and Area Deprivation Index (ADI) for the state of California. Univariate log-rank tests and Kaplan-Meier curves were used to assess differences in survival for predictors of interest. RESULTS: Between 2015 and 2021, 64 patients underwent surgery for metastatic disease of the spine. The mean age was 61.0 ± 12.5 years, with 60.9% being male (n = 39). In this cohort, 89.1% of patients were non-Hispanic (n = 57), 71.9% were White (n = 46), and 62.5% were insured by Medicare/Medicaid (n = 40). The mean SDI and ADI were 61.5 ± 28.0 and 7.7 ± 2.2, respectively. 28.1% of patients (n = 18) were diagnosed with primary cancer for the first time while 39.1% of patients (n = 25) were diagnosed with metastatic cancer for the first time. During index hospitalization, 37.5% of patients (n = 24) received palliative care consult. The 3-month, 6-month, and all-time mortality rates were 26.7% (n = 17), 39.5% (n = 23), and 50% (n = 32), respectively, with 10.9% of patients (n = 7) dying during their admission. Payor plan was significant at 3 months ( P = 0.02), and palliative consultation was significant at 3 months ( P = 0.007) and 6 months ( P = 0.03). No notable association was observed with SDI and ADI in quantiles or as continuous variables. DISCUSSION: In this study, 28.1% of patients were diagnosed with cancer for the first time. Three-month and 6-month mortality rates for patients undergoing surgery were 26.7% and 39.5%, respectively. Furthermore, mortality was markedly associated with palliative care consultation and insurance status, but not with SDI and ADI. LEVEL OF EVIDENCE: Retrospective case series, Level III evidence.

The Benefit of Addressing Malalignment in Revision Surgery for Proximal Junctional Kyphosis Following ASD Surgery.

STUDY DESIGN: Retrospective cohort study. OBJECTIVE: Understand the benefit of addressing malalignment in revision surgery for proximal junctional kyphosis (PJK). SUMMARY OF BACKGROUND DATA: PJK is a common cause of revision surgery for adult spinal deformity patients. During a revision, surgeons may elect to perform a proximal extension of the fusion, or also correct the source of the lumbopelvic mismatch. MATERIALS AND METHODS: Recurrent PJK following revision surgery was the primary outcome. Revision surgical strategy was the primary predictor (proximal extension of fusion alone compared with combined sagittal correction and proximal extension). Multivariable logistic regression determined rates of recurrent PJK between the two surgical groups with lumbopelvic surgical correction assessed through improving ideal alignment in one or more alignment criteria [Global Alignment and Proportionality (GAP), Roussouly-type, and Sagittal Age-Adjusted Score (SAAS)]. RESULTS: A total of 151 patients underwent revision surgery for PJK. PJK occurred at a rate of 43.0%, and PJF at 12.6%. Patients proportioned in GAP postrevision had lower rates of recurrent PJK [23% vs. 42%; odds ratio (OR): 0.3, 95% confidence interval (CI): 0.1-0.8, P =0.024]. Following adjusted analysis, patients who were ideally aligned in one of three criteria (Matching in SAAS and/or Roussouly matched and/or achieved GAP proportionality) had lower rates of recurrent PJK (36% vs. 53%; OR: 0.4, 95% CI: 0.1-0.9, P =0.035) and recurrent PJF (OR: 0.1, 95% CI: 0.02-0.7, P =0.015). Patients ideally aligned in two of three criteria avoid any development of PJF (0% vs. 16%, P <0.001). CONCLUSIONS: Following revision surgery for PJK, patients with persistent poor sagittal alignment showed increased rates of recurrent PJK compared with patients who had abnormal lumbopelvic alignment corrected during the revision. These findings suggest addressing the root cause of surgical failure in addition to proximal extension of the fusion may be beneficial.

Gender, Racial, and Ethnic Differences in the Utilization of Cervical Disk Replacement for Cervical Radiculopathy.

INTRODUCTION: Cervical radiculopathy (CR) is commonly treated by spine surgeons, with surgical options including anterior cervical diskectomy and fusion (ACDF) and cervical disk replacement (CDR). CDR is a motion-sparing alternative to ACDF and was approved by the US FDA in 2007. CDR utilization has increased because evidence has emerged demonstrating its long-term efficacy. Despite CDR's efficacy, studies have suggested that socioeconomic factors may influence which patients undergo CDR versus ACDF. Our objective was to determine whether gender, racial, and ethnic disparities exist in the utilization of CDR versus ACDF for CR. METHODS: Patients age ≥18 years undergoing elective CDR or ACDF for CR between 2017 and 2020 were identified in the Vizient Clinical Database. Proportions of patients undergoing CDR and ACDF, as well as their comorbidities, complications, and outcomes, were compared by sex, race, and ethnicity. Bonferroni correction was done for multiple comparisons. RESULTS: A total of 7,384 patients, including 1,427 undergoing CDR and 5,957 undergoing ACDF, were reviewed. Black patients undergoing surgical treatment of CR were less likely to undergo CDR than ACDF, had a longer length of stay, and had higher readmission rates, while Hispanic patients had higher complication rates than non-Hispanic patients. DISCUSSION: Important racial and ethnic disparities exist in CR treatment. Interventions are necessary to ensure equal access to spine care by reducing barriers, such as underinsurance and implicit bias. LEVEL OF EVIDENCE: IV (Case Series).

Current Orthopaedic Residency Letters of Recommendation Are Not Biased by Gender of Applicant.

Letters of recommendation (LORs) are highly influential in the residency selection process. Differences in language and length of LORs by gender have been demonstrated for applicants applying to surgical residencies and fellowships. This had yet to be studied in orthopaedic surgery. Given the gender disparity in the field, we sought to investigate the impact of gender on orthopaedic residency applicant LORs. We hypothesized that differences in length and language would be present for women applicants as compared to men. METHODS: LORs for 2019 to 2020 applicants who applied to a single academic institution were selected for review. Female and male applicants were matched by medical school attended and United States Medical Licensing Examination Step 1 score. LORs were analyzed using both qualitative and quantitative analyses. Letters were evaluated for their word count, presence of language terms, and frequency of language terms. A similar subgroup language analysis was performed for standardized LORs (SLORs). RESULTS: Six hundred fifty-six applicants met the initial screening criteria-126 women and 530 men. After matching, 71 female applicants were paired with 111 male applicants. Word count was, on average, longer for female applicants. LORs for female applicants were more likely to contain language terms that characterized their ability, achievement, participation in athletics, awards received, fit, leadership, and personality traits. Of these terms, ability and participation in athletics were also found more frequently in LORs written for women. In addition, language characterizing technical skills was found more frequently in LORs of female applicants. Similar codes were found to be statistically significant in the SLOR subgroup analysis. CONCLUSION: This study highlights that current orthopaedic surgery residency LORs do not appear to be biased by applicant gender. LORs were longer for female applicants and described them more positively. Future female orthopaedic residency applicants should be assured that current female candidates are applying with at least similar if not greater subjective qualifications to their male counterparts based on the findings of this study.

Prognostic value of laboratory values in older patients with cervical spine fractures.

OBJECTIVES: To understand the prognostic value of laboratory markers at presentation on post-treatment survival of patients 50 and older following cervical spine fracture. PATIENTS AND METHODS: We obtained clinical data on patients 50 and older treated for cervical spine fracture in a single healthcare system (2006-2016). Our primary outcome consisted of 1-year mortality, with mortality within 3-months of presentation considered secondarily. Our primary predictors included serum glucose, serum creatinine, platelet-lymphocyte ratio (PLR) and neutrophil-lymphocyte ratio (NLR) at presentation. We used multivariable logistic regression to adjust for confounding from sociodemographic and clinical characteristics. Point estimates and 95 % confidence intervals (CI) from the final model were refined using Bayesian regression techniques. RESULTS: We included 1781 patients in this analysis, with an average age of 75.3 (SD 12.0). The mortality rate at 3-months was 12 % and 17 % at 1-year. In multivariable testing, neither elevated PLR or NLR were significant predictors of 1-year mortality. Elevated serum creatinine was associated with increased mortality at 1-year (OR 1.89; 95 % CI 1.30, 2.74), as was hyperglycemia (OR 1.50; 95 % CI 1.06, 2.13). Elevated serum creatinine remained influential (OR 1.64; 95 % CI 1.06, 2.54) on mortality at 3-months. CONCLUSIONS: This is the first study to evaluate laboratory values at presentation in conjunction with survival following cervical fractures. The results can be used to help forecast natural history and in expectation management. They may also help formulate treatment plans, especially when the need for surgical intervention is not clearly defined.

Do Medicare Accountable Care Organizations Reduce Disparities After Spinal Fracture?

BACKGROUND: National changes in health care disparities within the setting of trauma care have not been examined within Accountable Care Organizations (ACOs) or non-ACOs. We sought to examine the impact of ACOs on post-treatment outcomes (in-hospital mortality, 90-day complications, and readmissions), as well as surgical intervention among whites and nonwhites treated for spinal fractures. MATERIALS AND METHODS: We identified all beneficiaries treated for spinal fractures between 2009 and 2014 using national Medicare fee for service claims data. Claims were used to identify sociodemographic and clinical criteria, receipt of surgery and in-hospital mortality, 90-day complications, and readmissions. Multivariable logistic regression analysis accounting for all confounders was used to determine the effect of race/ethnicity on outcomes. Nonwhites were compared with whites treated in non-ACOs between 2009 and 2011 as the referent. RESULTS: We identified 245,704 patients who were treated for spinal fractures. Two percent of the cohort received care in an ACO, whereas 7% were nonwhite. We found that disparities in the use of surgical fixation for spinal fractures were present in non-ACOs over the period 2009-2014 but did not exist in the context of care provided through ACOs (odds ratio [OR] 0.75; 95% confidence interval [CI] 0.44, 1.28). A disparity in the development of complications existed for nonwhites in non-ACOs (OR 1.09; 95% CI 1.01, 1.17) that was not encountered among nonwhites receiving care in ACOs (OR 1.32; 95% CI 0.90, 1.95). An existing disparity in readmission rates for nonwhites in ACOs over 2009-2011 (OR 1.34; 95% CI 1.01, 1.80) was eliminated in the period 2012-2014 (OR 0.85; 95% CI 0.65, 1.09). CONCLUSIONS: Our work reinforces the idea that ACOs could improve health care disparities among nonwhites. There is also the potential that as ACOs become more familiar with care integration and streamlined delivery of services, further improvements in disparities could be realized.

Changes in healthcare delivery following spinal fracture in Medicare Accountable Care Organizations.

BACKGROUND CONTEXT: Accountable Care Organizations (ACOs) were designed to reduce healthcare costs while simultaneously improving quality. Given that the success of ACOs is predicated on controlling costs, concerns have been expressed that patients could be adversely affected through restricted access to surgery, including in the context of spine fracture care. PURPOSE: Evaluate the impact of Medicare ACO formation on the utilization of surgery and outcomes following spinal fractures. STUDY DESIGN: Retrospective review of Medicare claims (2009-2014). PATIENT SAMPLE: Patients treated for spinal fractures in an ACO or non-ACO. OUTCOME MEASURES: The utilization of surgery as treatment for spinal fractures, in-hospital mortality, 90-day complications, or hospital readmission within 90-days injury. METHODS: We used a pre-post study design to compare outcomes for patients treated in ACOs versus non-ACOs. Receipt of surgery for treatment of a spinal fracture was the primary outcome, with mortality, complications and readmissions treated secondarily. We used multivariable logistic regression adjusting for confounders to determine the association between environment of care (ACO vs. non-ACO) and the outcomes of interest. In all testing, beneficiaries treated in non-ACOs during 2009 to 2011 were used as the referent. RESULTS: During 2009 to 2011, 9% (n=10,866) of patients treated in non-ACOs received surgery, whereas a similar percentage (9%; n=210) underwent surgery in ACOs. This figure decreased to 8% (n=9,857) for individuals treated in non-ACOs over 2012 to 2014, although the surgical rate remained unchanged for those receiving care in an ACO (9%; n=227). There was no difference in the use of surgery among patients treated in ACOs (OR 0.96; 95% CI 0.79, 1.18) over 2012 to 2014. Similar increases in the odds of mortality were observed for both ACOs and non-ACOs during this period. A marginal, yet significant increase in complications was observed among ACOs, although there was no change in the odds of readmission. CONCLUSIONS: Our study found that the formation of ACOs did not result in alterations in the use of surgery for spinal fractures or substantive changes in outcomes. As ACOs continue to evolve, more emphasis should be placed on the incorporation of measures directly related to surgical and trauma care in the determinants of risk-based reimbursements.