Do Hounsfield Units From Intraoperative CT Scans Correlate With Preoperative Values?

BACKGROUND: There is increasing interest in forecasting postoperative complications using bone density metrics. Vertebral Hounsfield unit measurements obtained from CT scans performed for surgical planning or other purposes, known as opportunistic CTs, have shown promise for their ease of measurement and the ability to target density measurement to a particular region of interest. Concomitant with the rising interest in prognostic bone density measurement use has been the increasing adoption of intraoperative advanced imaging techniques. Despite the interest in both outcome prognostication and intraoperative advanced imaging, there is little information regarding the use of CT-based intraoperative imaging as a means to measure bone density. QUESTIONS/PURPOSES: (1) Can vertebral Hounsfield units be reliably measured by physician reviewers from CT scans obtained intraoperatively? (2) Do Hounsfield units measured from intraoperative studies correlate with values measured from preoperative CT scans? METHODS: To be eligible for this retrospective study, patients had to have been treated with the use of an intraoperative CT scan for instrumented spinal fusion for either degenerative conditions or traumatic injuries between January 2015 and December 2022. Importantly, patients without a preoperative CT scan of the fused levels within 180 days before surgery or who were indicated for surgery because of infection, metastatic disease, or who were having revision surgery after prior instrumentation were excluded from the query. Of the 285 patients meeting these inclusion criteria, 53% (151) were initially excluded for the following reasons: 36% (102) had intraoperative CT scans obtained after placement of instrumentation, 16% (47) had undergone intraoperative CT scans but the studies were not accessible for Hounsfield unit measurement, and 0.7% (2) had prior kyphoplasty wherein the cement prevented Hounsfield unit measurement. Finally, an additional 19% (53) of patients were excluded because the preoperative CT and intraoperative CT were obtained at different peak voltages, which can influence Hounsfield unit measurement. This yielded a final population of 81 patients from whom 276 preoperative and 276 intraoperative vertebral Hounsfield unit measurements were taken. Hounsfield unit data were abstracted from the same vertebra(e) from both preoperative and intraoperative studies by two physician reviewers (one PGY3 and one PGY5 orthopaedic surgery resident, both pursuing spine surgery fellowships). For a small, representative subset of patients, measurements were taken by both reviewers. The feasibility and reliability of Hounsfield unit measurement were then assessed with interrater reliability of values measured from the same vertebra by the two different reviewers. To compare Hounsfield unit values from intraoperative CT scans with preoperative CT studies, an intraclass correlation using a two-way random effects, absolute agreement testing technique was employed. Because the data were formatted as multiple measurements from the same vertebra at different times, a repeated measures correlation was used to assess the relationship between preoperative and intraoperative Hounsfield unit values. Finally, a linear mixed model with patients handled as a random effect was used to control for different patient and clinical factors (age, BMI, use of bone density modifying agents, American Society of Anesthesiologists [ASA] classification, smoking status, and total Charlson comorbidity index [CCI] score). RESULTS: We found that Hounsfield units can be reliably measured from intraoperative CT scans by human raters with good concordance. Hounsfield unit measurements of 31 vertebrae from a representative sample of 10 patients, measured by both reviewers, demonstrated a correlation value of 0.82 (95% CI 0.66 to 0.91), indicating good correlation. With regard to the relationship between preoperative and intraoperative measurements of the same vertebra, repeated measures correlation testing demonstrated no correlation between preoperative and intraoperative measurements (r = 0.01 [95% CI -0.13 to 0.15]; p = 0.84). When controlling for patient and clinical factors, we continued to observe no relationship between preoperative and intraoperative Hounsfield unit measurements. CONCLUSION: As intraoperative CT and measurement of vertebral Hounsfield units both become increasingly popular, it would be a natural extension for spine surgeons to try to extract Hounsfield unit data from intraoperative CTs. However, we found that although it is feasible to measure Hounsfield data from intraoperative CT scans, the obtained values do not have any predictable relationship with values obtained from preoperative studies, and thus, these values should not be used interchangeably. With this knowledge, future studies should explore the prognostic value of intraoperative Hounsfield unit measurements as a distinct entity from preoperative measurements. LEVEL OF EVIDENCE: Level III, diagnostic study.

The utility of vertebral Hounsfield units as a prognostic indicator of adverse events following treatment of spinal epidural abscess.

Background: Spinal epidural abscesses (SEAs) are a devastating condition with high levels of associated morbidity and mortality. Hounsfield units (HUs), a marker of radiodensity on CT scans, have previously been correlated with adverse events following spinal interventions. We evaluated whether HUs might also be associated with all-cause complications and/or mortality in this high-risk population. Methods: This retrospective cohort study was carried out within an academic health system in the United States. Adults diagnosed with a SEA between 2006 and 2021 and who also had a CT scan characterizing their SEA within 6 months of diagnosis were considered. HUs were abstracted from the 4 vertebral bodies nearest to, but not including, the infected levels. Our primary outcome was the presence of composite 90-day complications and HUs represented the primary predictor. A multivariable logistic regression analysis was conducted adjusting for demographic and disease-specific confounders. In sensitivity testing, separate logistic regression analyses were conducted (1) in patients aged 65 and older and (2) with mortality as the primary outcome. Results: Our cohort consisted of 399 patients. The overall incidence of 90-day complications was 61.2% (n=244), with a 7.8% (n=31) 90-day mortality rate. Those experiencing complications were more likely to have undergone surgery to treat their SEA (58.6% vs. 46.5%; p=.018) but otherwise the cohorts were similar. HUs were not associated with composite 90-day complications (Odds ratio [OR] 1.00 [95% CI 1.00-1.00]; p=.842). Similar findings were noted in sensitivity testing. Conclusions: While HUs have previously been correlated with adverse events in certain clinical contexts, we found no evidence to suggest that HUs are associated with all-cause complications or mortality in patients with SEAs. Future research hoping to leverage 3-dimensional imaging as a prognostic measure in this patient population should focus on alternative targets. Level of Evidence: Level III; Observational Cohort study.

Intraoperative navigation increases the projected lifetime cancer risk in patients undergoing surgery for adolescent idiopathic scoliosis.

BACKGROUND CONTEXT: Adolescent idiopathic scoliosis (AIS) is a common condition, often requiring surgical correction. Computed tomography (CT) based navigation technologies, which rely on ionizing radiation, are increasingly being utilized for surgical treatment. Although this population is highly vulnerable to radiation, given their age and female predominance, there is little available information elucidating modeled iatrogenic cancer risk. PURPOSE: To model lifetime cancer risk associated with the use of intraoperative CT-based navigation for surgical treatment of AIS. STUDY DESIGN/SETTING: This retrospective cross-sectional study took place in a quaternary care academic pediatric hospital in the United States. PATIENT SAMPLE: Adolescents aged 10-18 who underwent posterior spinal fusion for a diagnosis of AIS between July 2014 and December 2019. OUTCOMES MEASURES: Effective radiation dose and projected lifetime cancer risk associated with intraoperative doses of ionizing radiation. METHODS: Clinical and radiographic parameters were abstracted, including total radiation dose during surgery from flat plate radiographs, fluoroscopy, and intraoperative CT scans. Multivariable regression analysis was used to assess differences in radiation exposure between patients treated with conventional radiography versus intraoperative navigation. Radiation exposure was translated into lifetime cancer risk using well-established algorithms. RESULTS: In total, 245 patients were included, 119 of whom were treated with navigation. The cohort was 82.9% female and 14.4 years of age. The median radiation exposure (in millisieverts, mSv) for fluoroscopy, radiography, and navigation was 0.05, 4.14, and 8.19 mSv, respectively. When accounting for clinical and radiographic differences, patients treated with intraoperative navigation received 8.18 mSv more radiation (95%CI: 7.22-9.15, p<.001). This increase in radiation projects to 0.90 iatrogenic malignancies per 1,000 patients (95%CI 0.79-1.01). CONCLUSIONS: Ours is the first work to define cancer risk in the setting of radiation exposure for navigated AIS surgery. We project that intraoperative navigation will generate approximately one iatrogenic malignancy for every 1,000 patients treated. Given that spine surgery for AIS is common and occurs in the context of a multitude of other radiation sources, these data highlight the need for radiation budgeting protocols and continued development of lower radiation dose technologies. LEVEL OF EVIDENCE: Therapeutic, III.

Validation of the Stopping Opioids After Surgery (SOS) Score for the Sustained Use of Prescription Opioids Following Orthopaedic Surgery.

BACKGROUND: The Stopping Opioids after Surgery (SOS) score was developed to identify patients at risk for sustained opioid use following surgery. The SOS score has not been specifically validated for patients in a general orthopaedic context. Our primary objective was to validate the SOS score within this context. METHODS: In this retrospective cohort study, we considered a broad array of representative orthopaedic procedures performed between January 1, 2018, and March 31, 2022. These procedures included rotator cuff repair, lumbar discectomy, lumbar fusion, total knee and total hip arthroplasty, open reduction and internal fixation (ORIF) of ankle fracture, ORIF of distal radial fracture, and anterior cruciate ligament reconstruction. The performance of the SOS score was evaluated by calculating the c-statistic, receiver operating characteristic curve, and the observed rates of sustained prescription opioid use (defined as uninterrupted prescriptions of opioids for ≥90 days) following surgery. For our sensitivity analysis, we compared these metrics among various time epochs related to the COVID-19 pandemic. RESULTS: A total of 26,114 patients were included, of whom 51.6% were female and 78.1% were White. The median age was 63 years. The observed prevalence of sustained opioid use was 1.3% (95% confidence interval [CI], 1.2% to 1.5%) in the low-risk group (SOS score of <30), 7.4% (95% CI, 6.9% to 8.0%) in the medium-risk group (SOS score of 30 to 60), and 20.8% (95% CI, 17.7% to 24.2%) in the high-risk group (SOS score of >60). The performance of the SOS score in the overall group was strong, with a c-statistic of 0.82. The performance of the SOS score showed no evidence of worsening over time. The c-statistic was 0.79 before the COVID-19 pandemic and ranged from 0.77 to 0.80 throughout the waves of the pandemic. CONCLUSIONS: We validated the use of the SOS score for sustained prescription opioid use following a diverse array of orthopaedic procedures across subspecialties. This tool is easy to implement for the purpose of prospectively identifying patients in musculoskeletal service lines who are at higher risk for sustained opioid use, thereby enabling the future implementation of upstream interventions and modifications to avert opioid abuse and to combat the opioid epidemic. LEVEL OF EVIDENCE: Diagnostic Level III . See Instructions for Authors for a complete description of levels of evidence.

Does the Stopping Opioids After Surgery Score Perform Well Among Racial and Socioeconomic Subgroups?

BACKGROUND: The Stopping Opioids After Surgery (SOS) score is a validated tool that was developed to determine the risk of sustained opioid use after surgical interventions, including orthopaedic procedures. Despite prior investigations validating the SOS score in diverse contexts, its performance across racial, ethnic, and socioeconomic subgroups has not been assessed. QUESTIONS/PURPOSES: In a large, urban, academic health network, did the performance of the SOS score differ depending on (1) race and ethnicity or (2) socioeconomic status? METHODS: This retrospective investigation was conducted using data from an internal, longitudinally maintained registry of a large, urban, academic health system in the Northeastern United States. Between January 1, 2018, and March 31, 2022, we treated 26,732 adult patients via rotator cuff repair, lumbar discectomy, lumbar fusion, TKA, THA, ankle or distal radius open reduction and internal fixation, or ACL reconstruction. We excluded 1% of patients (274 of 26,732) because of missing length of stay information, 0.06% (15) for missing discharge information, 1% (310) for missing medication information related to loss to follow-up, and 0.07% (19) who died during their hospital stay. Based on these inclusion and exclusion criteria, 26,114 adult patients were left for analysis. The median age in our cohort was 63 years (IQR 52 to 71), and most patients were women (52% [13,462 of 26,114]). Most patients self-reported their race and ethnicity as non-Hispanic White (78% [20,408 of 26,114]), but the cohort also included non-Hispanic Black (4% [939]), non-Hispanic Asian (2% [638]), and Hispanic (1% [365]) patients. Five percent (1295) of patients were of low socioeconomic status, defined by prior SOS score investigations as patients with Medicaid insurance. Components of the SOS score and the observed frequency of sustained postoperative opioid prescriptions were abstracted. The performance of the SOS score was compared across racial, ethnic, and socioeconomic subgroups using the c-statistic, which measures the capacity of the model to differentiate between patients with and without sustained opioid use. This measure should be interpreted on a scale between 0 and 1, where 0 represents a model that perfectly predicts the wrong classification, 0.5 represents performance no better than chance, and 1.0 represents perfect discrimination. Scores less than 0.7 are generally considered poor. The baseline performance of the SOS score in past investigations has ranged from 0.76 to 0.80. RESULTS: The c-statistic for non-Hispanic White patients was 0.79 (95% CI 0.78 to 0.81), which fell within the range of past investigations. The SOS score performed worse for Hispanic patients (c-statistic 0.66 [95% CI 0.52 to 0.79]; p < 0.001), where it tended to overestimate patients' risks of sustained opioid use. The SOS score for non-Hispanic Asian patients did not perform worse than in the White patient population (c-statistic 0.79 [95% CI 0.67 to 0.90]; p = 0.65). Similarly, the degree of overlapping CIs suggests that the SOS score did not perform worse in the non-Hispanic Black population (c-statistic 0.75 [95% CI 0.69 to 0.81]; p = 0.003). There was no difference in score performance among socioeconomic groups (c-statistic 0.79 [95% CI 0.74 to 0.83] for socioeconomically disadvantaged patients; 0.78 [95% CI 0.77 to 0.80] for patients who were not socioeconomically disadvantaged; p = 0.92). CONCLUSION: The SOS score performed adequately for non-Hispanic White patients but performed worse for Hispanic patients, where the 95% CI nearly included an area under the curve value of 0.5, suggesting that the tool is no better than chance at predicting sustained opioid use for Hispanic patients. In the Hispanic population, it commonly overestimated the risk of opioid dependence. Its performance did not differ among patients of different sociodemographic backgrounds. Future studies might seek to contextualize why the SOS score overestimates expected opioid prescriptions for Hispanic patients and how the utility performs among more specific Hispanic subgroups. CLINICAL RELEVANCE: The SOS score is a valuable tool in ongoing efforts to combat the opioid epidemic; however, disparities exist in terms of its clinical applicability. Based on this analysis, the SOS score should not be used for Hispanic patients. Additionally, we provide a framework for how other predictive models should be tested in various lesser-represented populations before implementation.

Projected Lifetime Cancer Risk Associated With Intraoperative Computed Tomography for Lumbar Spine Surgery.

STUDY DESIGN: Retrospective cross-sectional study. OBJECTIVE: (1) To determine the incremental increase in intraoperative ionizing radiation conferred by computed tomography (CT) as compared with conventional radiography; and (2) to model different lifetime cancer risks contextualized by the intersection between age, sex, and intraoperative imaging modality. SUMMARY OF BACKGROUND DATA: Emerging technologies in spine surgery, like navigation, automation, and augmented reality, commonly utilize intraoperative CT. Although much has been written about the benefits of such imaging modalities, the inherent risk profile of increasing intraoperative CT has not been well evaluated. MATERIALS AND METHODS: Effective doses of intraoperative ionizing radiation were extracted from 610 adult patients who underwent single-level instrumented fusion for lumbar degenerative or isthmic spondylolisthesis from January 2015 through January 2022. Patients were divided into those who received intraoperative CT (n=138) and those who underwent conventional intraoperative radiography (n=472). Generalized linear modeling was utilized with intraoperative CT use as a primary predictor and patient demographics, disease characteristics, and preference-sensitive intraoperative considerations ( e.g. surgical approach and surgical invasiveness) as covariates. The adjusted risk difference in radiation dose calculated from our regression analysis was used to prognosticate the associated cancer risk across age and sex strata. RESULTS: (1) After adjusting for covariates, intraoperative CT was associated with 7.6 mSv (interquartile range: 6.8-8.4 mSv; P <0.001) more radiation than conventional radiography. (2) For the median patient in our population (a 62-year-old female), intraoperative CT use increased lifetime cancer risk by 2.3 incidents (interquartile range: 2.1-2.6) per 10,000. Similar projections for other age and sex strata were also appreciated. CONCLUSIONS: Intraoperative CT use significantly increases cancer risk compared with conventional intraoperative radiography for patients undergoing lumbar spinal fusions. As emerging technologies in spine surgery continue to proliferate and leverage intraoperative CT for cross-sectional imaging data, strategies must be developed by surgeons, institutions, and medical technology companies to mitigate long-term cancer risks.

Intraoperative CT for lumbar fusion is not associated with improved short- or long-term complication profiles.

BACKGROUND CONTEXT: The use of intraoperative CT has continued to grow in recent years, as various techniques leverage the promise of improved instrumentation accuracy and the hope for decreased complications. Nonetheless, the literature regarding the short- and long-term complications associated with such techniques remains scant and/or confounded by indication and selection bias. PURPOSE: To use causal inference techniques to determine whether intraoperative CT use is associated with an improved complication profile as compared to conventional radiography for single-level lumbar fusions, an increasingly commonplace application for this technology. STUDY DESIGN/SETTING: Inverse probability weighted retrospective cohort study carried out within a large integrated health care network. PATIENT SAMPLE: Adult patients who underwent surgical treatment of spondylolisthesis via lumbar fusion from January 2016 to December 2021. OUTCOME MEASURES: Our primary outcome was the incidence rate of revision surgery. Our secondary outcome was the incidence of composite 90-day complications (deep and superficial surgical site infection, venous thromboembolic events, and unplanned readmissions). METHODS: Demographics, intraoperative information, and postoperative complications were abstracted from electronic health records. A propensity score was developed utilizing a parsimonious model to account for covariate interaction with our primary predictor, intraoperative imaging technique. This propensity score was utilized in the creation of inverse probability weights to adjust for indication and selection bias. The rate of revisions within 3 years as well as the rate of revisions at any time-point were compared between cohorts using Cox regression analysis. The incidence of composite 90-day complications were compared using negative binomial regression. RESULTS: Our patient population consisted of 583 patients, with 132 who underwent intraoperative CT and 451 who underwent conventional radiographic techniques. There were no significant differences between cohorts following inverse probability weighting. No significant differences were detected in 3-year revision rates (HR, 0.74 [95% CI 0.29, 1.92]; p=.5), overall revision rates (HR, 0.54 [95% CI 0.20, 1.46]; p=.2), or 90-day complications (RC -0.24 [95% CI -1.35, 0.87]; p=.7). CONCLUSIONS: Intraoperative CT use was not associated with an improved complication profile in either the short- or long-term for patients undergoing single-level instrumented fusion. This observed clinical equipoise should be weighed against resource and radiation-related costs when considering intraoperative CT for low complexity fusions.

Development of a machine learning algorithm to identify surgical candidates for hip and knee arthroplasty without in-person evaluation.

INTRODUCTION: Arthroplasty care delivery is facing a growing supply-demand mismatch. To meet future demand for joint arthroplasty, systems will need to identify potential surgical candidates prior to evaluation by orthopaedic surgeons. MATERIALS AND METHODS: Retrospective review was conducted at two academic medical centers and three community hospitals from March 1 to July 31, 2020 to identify new patient telemedicine encounters (without prior in-person evaluation) for consideration of hip or knee arthroplasty. The primary outcome was surgical indication for joint replacement. Five machine learning algorithms were developed to predict likelihood of surgical indication and assessed by discrimination, calibration, overall performance, and decision curve analysis. RESULTS: Overall, 158 patients underwent new patient telemedicine evaluation for consideration of THA, TKA, or UKA and 65.2% (n = 103) were indicated for operative intervention prior to in-person evaluation. The median age was 65 (interquartile range 59-70) and 60.8% were women. Variables found to be associated with operative intervention were radiographic degree of arthritis, prior trial of intra-articular injection, trial of physical therapy, opioid use, and tobacco use. In the independent testing set (n = 46) not used for algorithm development, the stochastic gradient boosting algorithm achieved the best performance with AUC 0.83, calibration intercept 0.13, calibration slope 1.03, Brier score 0.15 relative to a null model Brier score of 0.23, and higher net benefit than the default alternatives on decision curve analysis. CONCLUSION: We developed a machine learning algorithm to identify potential surgical candidates for joint arthroplasty in the setting of osteoarthritis without an in-person evaluation or physical examination. If externally validated, this algorithm could be deployed by various stakeholders, including patients, providers, and health systems, to direct appropriate next steps in patients with osteoarthritis and improve efficiency in identifying surgical candidates. LEVEL OF EVIDENCE: III.

Projected lifetime cancer risk for patients undergoing spine surgery for isthmic spondylolisthesis.

BACKGROUND CONTEXT: Radiographs, fluoroscopy, and computed tomography (CT) are increasingly utilized in the diagnosis and management of various spine pathologies. Such modalities utilize ionizing radiation, a known cause of carcinogenesis. While the radiation doses such studies confer has been investigated previously, it is less clear how such doses translate to projected cancer risks, which may be a more interpretable metric. PURPOSE: (1) Calculate the lifetime cancer risk and the relative contributions of preference-sensitive selection of imaging modalities associated with the surgical management of a common spine pathology, isthmic spondylolisthesis (IS); (2) Investigate whether the use of intraoperative CT, which is being more pervasively adopted, increases the risk of cancer. STUDY DESIGN/SETTING: Retrospective cross-sectional study carried out within a large integrated health care network. PATIENT SAMPLE: Adult patients who underwent surgical treatment of IS via lumbar fusion from January 2016 through December 2021. OUTCOME MEASURES: (1) Effective radiation dose and lifetime cancer risk associated with each exposure to ionizing radiation; (2) Difference in effective radiation dose (and lifetime cancer risk) among patients who received intraoperative CT compared to other intraoperative imaging techniques. METHODS: Baseline demographics and differences in surgical techniques were characterized. Radiation exposure data were collected from the 2-year period centered on the operative date. Projected risk of cancer from this radiation was calculated utilizing each patient's effective radiation dose in combination with age and sex. Generalized linear modeling was used to adjust for covariates when determining the comparative risk of intraoperative CT as compared to alternative imaging modalities. RESULTS: We included 151 patients in this cohort. The range in calculated cancer risk exclusively from IS management was 1.3-13 cases of cancer per 1,000 patients. During the intraoperative period, CT imaging was found to significantly increase radiation exposure as compared to alternate imaging modalities (adjusted risk difference (ARD) 12.33mSv; IQR 10.04, 14.63mSv; p<.001). For a standardized 40 to 49-year-old female, this projects to an additional 0.72 cases of cancer per 1,000. For the entire 2-year perioperative care episode, intraoperative CT as compared to other intraoperative imaging techniques was not found to increase total ionizing radiation exposure (ARD 9.49mSv; IQR -0.83, 19.81mSv; p=.072). The effect of intraoperative imaging choice was mitigated in part due to preoperative (ARD 13.1mSv, p<.001) and postoperative CTs (ARD 22.7mSv, p<.001). CONCLUSIONS: Preference-sensitive imaging decisions in the treatment of IS impart substantial cancer risk. Important drivers of radiation exposure exist in each phase of care, including intraoperative CT and/or CT scans during the perioperative period. Knowledge of these data warrant re-evaluation of current imaging protocols and suggest a need for the development of radiation-sensitive approaches to perioperative imaging.

The Variability and Contributions to Cost of Anterior Cervical Discectomy and Fusion Constructs.

STUDY DESIGN: This was a retrospective cohort study. OBJECTIVE: To characterize the variability in cost for anterior cervical discectomy and fusion (ACDF) constructs and to identify key predictors of procedural cost. SUMMARY OF BACKGROUND DATA: ACDF is commonly performed for surgical treatment of cervical radiculopathy and myelopathy. Numerous biomechanical constructs and graft/biological options are available, with most demonstrating relatively equivalent clinical results. Despite the substantial focus on value in spine care, the differences and contributions to procedural cost in ACDF have not been well defined. MATERIALS AND METHODS: We evaluated the records of patients who underwent a single level ACDF from 2016 to 2020 at 4 hospitals in a major metropolitan area. We abstracted demographics, insurance status, operative time, diagnosis, surgeon, institution, and components of procedural costs. Costs based on construct were compared using multivariable adjusted analyses using negative binomial regression. The primary outcome measures were cost differences between ACDF techniques. RESULTS: Two hundred sixty-four patients were included, with procedures by 13 surgeons across 4 institutions. The total procedural cost for ACDF had a mean of US$2317 with wide variation (range, US$967-US$7370). Multivariable analysis revealed body mass index and use of polyether ether ketone to be correlated with increased cost while carbon fiber and autograft correlated with decreased cost. When comparing standalone device constructs to cases with anterior instrumentation (plate/screws), the total cost was significantly higher in the plate/screw group (US$2686±US$921 vs. US$1466±US$878, P <0.001). CONCLUSIONS: We encountered wide variation in procedural costs associated with ACDF, including as much as an 8-fold difference in the cost of constructs. The most important drivers included instrumentation type and implant materials. Here, we identify potential targets of opportunity for health care organizations that are looking to reduce variance in procedural expenditures to improve health care savings associated with the performance of ACDF.

Changes in Elective and Urgent Surgery Among TRICARE Beneficiaries During the COVID-19 Pandemic.

BACKGROUND: COVID-19 is known to have altered the capacity to perform surgical procedures in numerous health care settings. The impact of this change within the direct and private-sector settings of the Military Health System has not been effectively explored, particularly as it pertains to disparities in surgical access and shifting of services between sectors. We sought to characterize how the COVID-19 pandemic influenced access to care for surgical procedures within the direct and private-sector settings of the Military Health System. METHODS: We retrospectively evaluated claims for patients receiving urgent and elective surgical procedures in March-September 2017, 2019, and 2020. The pre-COVID period consisted of 2017 and 2019 and was compared to 2020. We adjusted for sociodemographic characteristics, medical comorbidities, and region of care using multivariable Poisson regression. Subanalyses considered the impact of race and sponsor rank as a proxy for socioeconomic status. RESULTS: During the period of the COVID-19 pandemic, there was no significant difference in the adjusted rate of urgent surgical procedures in direct (risk ratio, 1.00; 95% CI, 0.97-1.03) or private-sector (risk ratio, 0.99; 95% CI, 0.97-1.02) care. This was also true for elective surgeries in both settings. No significant disparities were identified in any of the racial subgroups or proxies for socioeconomic status we considered in direct or private-sector care. CONCLUSIONS: We found a similar performance of elective and urgent surgeries in both the private sector and direct care during the first 6 months of the COVID-19 pandemic. Importantly, no racial disparities were identified in either care setting.

C-reactive Protein-to-albumin Ratio in Spinal Epidural Abscess: Association with Post-treatment Complications.

INTRODUCTION: Spinal epidural abscess (SEA) is a complex medical condition with high morbidity and healthcare costs. Clinical presentation and laboratory data may have prognostic value in forecasting morbidity and mortality. C-reactive protein-to-albumin ratio (CAR) demonstrates promise for the prediction of adverse events in multiple orthopaedic and nonorthopaedic surgical conditions. We investigated the relationship between CAR and outcomes after treatment of SEA. METHODS: We retrospectively evaluated adult patients treated within a single healthcare system for a diagnosis of SEA (2005 to 2017). Laboratory and clinical data included age at diagnosis, sex, race, body mass index, smoking status, history of intravenous drug use, Charlson Comorbidity Index, and CAR. The primary outcome was the occurrence of any complication; mortality and readmissions were considered secondarily. We used logistic regression to determine the association between baseline CAR and outcomes, adjusting for confounders. RESULTS: We included 362 patients with a 90-day mortality rate of 13.3% and a 90-day complication rate of 47.8%. A reduced complication rate was observed in the lowest decile of CAR values compared with the remaining 90% of patients, a threshold value of 2.5 (27.0% versus 50.2%; odds ratio [OR] 2.66, 95% confidence interval [CI] 1.22 to 5.81). CAR values in the highest two deciles experienced significantly increased odds of complications compared with the lowest decile (80th: OR 3.44; 95% CI 1.25 to 9.42; 90th: OR 3.28; 95% CI 1.19 to 9.04). DISCUSSION: We found elevated CAR to be associated with an increased likelihood of major morbidity in SEA. We suggest using a CAR value of 2.5 as a threshold for enhanced surveillance and recognizing patients with values above 73.7 as being at exceptional risk of morbidity. LEVEL OF EVIDENCE: Level III observational cohort study.

Microendoscopic Decompression for Lumbar Disc Herniations: An Analysis of Short and Long Term Patient Reported Outcome Measures.

INTRODUCTION: Endoscopic spine surgery is increasingly being used, and techniques, platforms, and applications are rapidly evolving. Despite substantial enthusiasm surrounding these techniques, there is a dearth of longer term patient-reported clinical outcomes. Within the United States in particular, there are yet to be reported large cohort studies with a notable follow-up. We sought to characterize the clinical outcomes of patients undergoing microendoscopic decompression (MED) for lumbar disk herniations. METHODS: The records of patients with symptomatic lumbar disk herniations who underwent MED from May 2018 to February 2021 within a single practice were reviewed. Paired outcomes scores were evaluated using Patient-Reported Outcomes Measurement Information System parameters. Basic perioperative data including length of stay, estimated blood loss, mean opioid use, complication rate, and rate of revision were tabulated. Paired sample Student t-tests and paired Wilcoxon sign tests were used to compare normally distributed and nonparametric data, respectively. RESULTS: Thirty-five patients with complete paired patient-reported outcome measures data and a minimum 6-month follow-up were included; 65.7% of the patients were male with a mean age of 47.1 years (SE 1.8). The mean follow-up was 590.6 days (SE 47.7). In total, 34 of the 35 patients (97.1%) were discharged on the day of their procedure. The estimated blood loss was <25 mL for each procedure. The mean opioid use after extubation and before discharge was 10.4 morphine milligram equivalents. At the 2-week follow-up, there were notable improvements in pain metrics and global health components. At the final follow-up, nearly all parameters showed notable improvement that exceeded minimally clinical important difference values. For most parameters, preoperative values outside of the "normal" range were within normal limits on postoperative testing. DISCUSSION: MED resulted in sustained notable improvement in patient-reported outcome measures that exceeded minimally clinical important difference values at the average follow-up approximating 2 years. These findings substantiate the utility of this technique and additional investment in endoscopic spine technology. DATA AVAILABILITY: Not publicly available; available upon request.

Lateral interbody release for fused vertebrae via transpsoas approach in adult spinal deformity surgery: a preliminary report of radiographic and clinical outcomes.

BACKGROUND: Lateral interbody release (LIR) via a transpsoas lateral approach is a surgical strategy to address degenerative lumbar scoliosis (DLS) patients with anterior autofusion of vertebral segments. This study aimed to characterize the clinical and radiographic outcomes of this lumbar reconstruction strategy using LIR to achieve anterior column correction. METHODS: Data for 21 fused vertebrae in 17 consecutive patients who underwent LIR between January 2014 and March 2020 were reviewed. Demographic and intraoperative data were recorded. Radiographic parameters were assessed preoperatively and at final follow-up, including segmental lordotic angle (SLA), segmental coronal angle (SCA), bone union rate, pelvic incidence (PI), lumbar lordosis (LL), pelvic tilt, sacral slope, PI-LL mismatch, sagittal vertical axis, Cobb angle, and deviation of the C7 plumb line from the central sacral vertical line. Clinical outcomes were evaluated using Oswestry Disability Index (ODI), visual analog scale (VAS) scores for low back and leg pain, and the short form 36 health survey questionnaire (SF-36) postoperatively and at final follow-up. Complications were also assessed. RESULTS: Mean patient age was 70.3 ± 4.8 years and all patients were female. Average follow-up period was 28.4 ± 15.3 months. Average procedural time to perform LIR was 21.3 ± 9.7 min and was not significantly different from traditional lateral interbody fusion at other levels. Blood loss per single segment during LIR was 38.7 ± 53.2 mL. Fusion rate was 100.0% in this cohort. SLA improved significantly from - 7.6 ± 9.2 degrees preoperatively to 7.0 ± 8.8 degrees at final observation and SCA improved significantly from 19.1 ± 7.8 degrees preoperatively to 8.7 ± 5.9 degrees at final observation (P < 0.0001, and < 0.0001, respectively). All spinopelvic and coronal parameters, as well as ODI and VAS, improved significantly. Incidence of peri- and postoperative complications such as iliopsoas muscle weakness and leg numbness in patients who underwent LIR was as much as XLIF. Incidence of postoperative mechanical failure following LIR was also similar to XLIF. Reoperation rate was 11.8%. However, there were no reoperations associated with LIR segments. CONCLUSIONS: The LIR technique for anterior column realignment of fused vertebrae in the context of severe ASD may be an option of a safe and effective surgical strategy.

Microendoscopic decompression of conjoined lumbosacral nerve roots.

Nerve root morphological variability is often incompletely appreciated on preoperative imaging and can complicate intraoperative decision-making. This case demonstrates the utility of spinal endoscopy in the visualisation and manipulation of conjoined nerve roots and includes procedural images to promote better understanding and awareness of this anatomical anomaly. A woman in her 50s presented with 1 year of progressive left S1 radiculopathy refractory to non-operative modalities. History and examination were notable for S1 dermatomal paresthesias, positive ipsilateral straight leg raise and grade 4/5 gastrocnemius strength. MRI demonstrated an L5-S1 left paracentral disc herniation causing severe lateral recess stenosis. Endoscopic decompression revealed conjoined lumbosacral nerve roots. Laminotomies and discectomy provided circumferential decompression. The patient experienced immediate and sustained relief of her preoperative radiculopathy as manifested in patient-reported outcome measures. Evolving endoscopic spine platforms provide novel visualisation of nerve root anomalies yielding new insight on safe and effective decompressive techniques.

Health-Care Utilization and Expenditures Associated with Long-Term Treatment After Combat and Non-Combat-Related Orthopaedic Trauma.

BACKGROUND: The long-term consequences of musculoskeletal trauma can be profound and can extend beyond the post-injury period. The surveillance of long-term expenditures among individuals who sustain orthopaedic trauma has been limited in prior work. We sought to compare the health-care requirements of active-duty individuals who sustained orthopaedic injuries in combat and non-combat (United States) environments using TRICARE claims data. METHODS: We identified service members who sustained combat or non-combat musculoskeletal injuries between 2007 and 2011. Combat-injured personnel were matched to those in the non-combat-injured cohort on a 1:1 basis using biologic sex, year of the injury, Injury Severity Score (ISS), and age at the index hospitalization. Health-care utilization was surveyed through 2018. The total health-care expenditures over the post-injury period were the primary outcome. These were assessed as a total overall cost and then as costs adjusted per year of follow-up. We used negative binomial regression to identify the independent association between risk factors and health-care expenditures. RESULTS: We identified 2,119 individuals who sustained combat-related orthopaedic trauma and 2,119 individuals who sustained non-combat injuries. The most common mechanism of injury within the combat-injured cohort was blast-related trauma (59%), and 418 individuals (20%) sustained an amputation. The total costs were $156,886 for the combat-injured group compared with $55,873 for the non-combat-injured group (p < 0.001). Combat-related orthopaedic injuries were associated with a 43% increase in health-care expenditures (incidence rate ratio, 1.43 [95% confidence interval, 1.19 to 1.73]). Severe ISS at presentation, ≥2 comorbidities, and amputations were also significantly associated with health-care utilization, as was junior enlisted rank, our proxy for socioeconomic status. CONCLUSIONS: Health-care requirements and associated costs are substantial among service members sustaining combat and non-combat orthopaedic trauma. Given the sociodemographic characteristics of our cohort, we believe that these results are translatable to civilians who sustain similar types of musculoskeletal trauma.

A Natural History of Patients Treated Operatively and Nonoperatively for Spinal Metastases Over 2 Years Following Treatment: Survival and Functional Outcomes.

STUDY DESIGN: Prospective observational study. OBJECTIVE: We present the natural history, including survival and function, among participants in the prospective observational study of spinal metastases treatment investigation. SUMMARY OF BACKGROUND DATA: Surgical treatment has been touted as a means to preserve functional independence, quality of life, and survival. Nearly all prior investigations have been limited by retrospective design and relatively short-periods of post-treatment surveillance. METHODS: This natural history study was conducted using the records of patients who were enrolled in the prospective observational study of spinal metastases treatment study (2017-2019). Eligible participants were 18 or older and presenting for treatment of spinal metastatic disease. Patients were followed at predetermined intervals (1, 3, 6, 12, and 24-mo) following treatment. We conducted cox proportional hazard regression analysis adjusting for confounders including age, biologic sex, number of comorbidities, type of metastatic lesion, neurologic symptoms at presentation, number of metastases involving the vertebral body, vertebral body collapse, New England Spinal Metastasis Score (NESMS) at presentation, and treatment strategy. RESULTS: We included 202 patients. Twenty-three percent of the population had died by 3 months following treatment initiation, 51% by 1 year, and 70% at 2 years. There was no significant difference in survival between patients treated operatively and nonoperatively (P = 0.16). No significant difference in HRQL between groups was appreciated beyond 3 months following treatment initiation. NESMS at presentation (scores of 0 [HR 5.61; 95% CI 2.83, 11.13] and 1 [HR 3.00; 95% CI 1.60, 5.63]) was significantly associated with mortality. CONCLUSION: We found that patients treated operatively and nonoperatively for spinal metastases benefitted from treatment in terms of HRQL. Two-year mortality for the cohort as a whole was 70%. When prognosticating survival, the NESMS appears to be an effective utility, particularly among patients with scores of 0 or 1.Level of Evidence: 2.

Spinal endoscopy: evidence, techniques, global trends, and future projections.

The utilization of indirect visualization during procedures has been increasingly replacing traditional forms of direct visualization across many different surgical specialties. The adoption of arthroscopy, using small cameras placed inside joints, has transformed musculoskeletal care over the last several decades, allowing surgeons to provide the same anatomic solutions with less tissue dissection, resulting in lower requirements for inpatient care, reduced costs, and expedited recovery.  For a variety of reasons, spine surgery has lagged behind other specialties in the adoption of indirect visualization.  Nonetheless, patient demand for less invasive spine procedures and surgeon drive to provide these solutions and improve care quality has driven global adoption of spinal endoscopy.  There are numerous endoscopic platforms and techniques currently utilized, and these systems are rapidly evolving.  Additionally, the variance in technology and health system incentives across the globe has generated tremendous regional heterogeneity in the utilization of spinal endoscopic procedures.  We present a consolidated review, including the background, evidence, techniques, and trends in spinal endoscopy, so that clinicians can gain a deeper understanding of this rapidly evolving domain of spinal healthcare.

Telemedicine visits generate accurate surgical plans across orthopaedic subspecialties.

INTRODUCTION: The role of telemedicine is rapidly evolving across medical specialties and orthopaedics. The utility of telemedicine to identify operative candidates and determine surgical plans has yet to be demonstrated. We sought to assess whether surgical plans proposed following telemedicine visits changed after subsequent in-person interaction across orthopaedic subspecialties. MATERIALS AND METHODS: We identified all elective telemedicine encounters across two academic institutions from March 1, 2020 to July 31, 2020. We identified patients indicated for surgery with a specific surgical plan during the virtual visit. The surgical plans delineated during the telemedicine encounter were then compared to final pre-operative plans documented following subsequent in-person evaluation. Changes in the surgical plan between telemedicine and in-person encounters were defined using a standardised schema. Regression analysis was used to evaluate factors associated with a change in surgical plan between visits across specialties, including the number of virtual examination manoeuvres performed. RESULTS: We identified 303 instances of a patient being indicated for orthopaedic surgery during a telemedicine encounter. In 11 cases (4%), the plan was changed between telemedicine and subsequent in-person encounter. No plans were changed amongst patients indicated for joint arthroplasty and foot and ankle surgery, whilst 4% of plans were changed amongst sports surgery and upper extremity/shoulder surgery. Surgical plans had the highest rate of change amongst spine surgery patients (8%). There was notable variability in the conduct of virtual examinations across subspecialties. CONCLUSION: Our results demonstrate the capability of telemedicine to support development of accurate surgical plans for orthopaedic patients across several subspecialties. Our findings also highlight the substantial variation in the utilisation of physical examination manoeuvres conducted via telemedicine across institutions, subspecialties, and providers. DESCRIPTION OF STUDY TYPE: Level IV, retrospective cohort study.