How dimensions can guide surgical planning and training: a systematic review of Kambin's triangle.

OBJECTIVE: The authors sought to analyze the current literature to determine dimensional trends across the lumbar levels of Kambin's triangle, clarify the role of imaging techniques for preoperative planning, and understand the effect of inclusion of the superior articular process (SAP). This compiled knowledge of the triangle is needed to perform successful procedures, reduce nerve root injuries, and help guide surgeons in training. METHODS: The authors performed a search of multiple databases using combinations of keywords: Kambin's triangle, size, measurement, safe triangle, and bony triangle. Articles were included if their main findings included measurement of Kambin's triangle. The PubMed, Scopus, Ovid, Cochrane, Embase, and Medline databases were systematically searched for English-language articles with no time frame restrictions through July 2022. RESULTS: Eight studies comprising 132 patients or cadavers were included in the study. The mean ± SD age was 66.69 ± 9.6 years, and 53% of patients were male. Overall, the size of Kambin's triangle increased in area moving down vertebral levels, with L5-S1 being the largest (133.59 ± 4.36 mm2). This trend followed a linear regression model when SAP was kept (p = 0.008) and removed (p = 0.003). There was also a considerable increase in the size of Kambin's triangle if the SAP was removed. CONCLUSIONS: Here, the authors have provided the first reported systematic review of the literature of Kambin's triangle, its measurements at each lumbar level, and key areas of debate related to the definition of the working safe zone. These findings indicate that CT is heavily utilized for imaging of the safe zone, the area of Kambin's triangle tends to increase caudally, and variation exists between patients. Future studies should focus on using advanced imaging techniques for preoperative planning and establishing guidelines for surgeons.

Interhospital transfer status for spinal metastasis patients in the United States is associated with more severe clinical presentations and higher rates of inpatient complications.

OBJECTIVE: In patients with metastatic spinal disease (MSD), interhospital transfer can potentially impact clinical outcomes as the possible benefits of transferring a patient to a higher level of care must be weighed against the negative effects associated with potential delays in treatment. While the association of clinical outcomes and transfer status has been examined in other specialties, the relationship between transfer status, complications, and risk of mortality in patients with MSD has yet to be explored. The purpose of this study was to examine the impact of transfer status on in-hospital mortality and clinical outcomes in patients diagnosed with MSD. METHODS: The National (Nationwide) Inpatient Sample (NIS) database was retrospectively queried for adult patients diagnosed with vertebral pathological fracture and/or spinal cord compression in the setting of metastatic disease between 2012 and 2014. Demographics, baseline characteristics (e.g., metastatic spinal cord compression [MSCC] and paralysis), comorbidities, type of intervention, and relevant patient outcomes were controlled in a multivariable logistic regression model to analyze the association of transfer status with patient outcomes. RESULTS: Within the 10,360 patients meeting the inclusion and exclusion criteria, higher rates of MSCC (50.2% vs 35.9%, p < 0.001) and paralysis (17.3% vs 8.4%, p < 0.001) were observed in patients transferred between hospitals compared to those directly admitted. In univariable analysis, a higher percentage of transferred patients underwent surgical intervention (p < 0.001) when compared with directly admitted patients. After controlling for significant covariates and surgical intervention, transferred patients were more likely to develop in-hospital complications (OR 1.34, 95% CI 1.18-1.52, p < 0.001), experience prolonged length of stay (OR 1.33, 95% CI 1.16-1.52, p < 0.001), and have a discharge disposition other than home (OR 1.70, 95% CI 1.46-1.98, p < 0.001), with no significant difference in inpatient mortality rates. CONCLUSIONS: Patients with MSD who were transferred between hospitals demonstrated more severe clinical presentations and higher rates of inpatient complications compared to directly admitted patients, despite demonstrating no difference in in-hospital mortality rates.

Incidence of Congenital Spinal Abnormalities Among Pediatric Patients and Their Association With Scoliosis and Systemic Anomalies.

BACKGROUND: Congenital abnormalities when present, according to VACTERL theory, occur nonrandomly with other congenital anomalies. This study estimates the prevalence of congenital spinal anomalies, and their concurrence with other systemic anomalies. METHODS: A retrospective cohort analysis on Health care Cost and Utilization Project's Kids Inpatient Database (KID), years 2000, 2003, 2006, 2009 was performed. ICD-9 coding identified congenital anomalies of the spine and other body systems. OUTCOME MEASURES: Overall incidence of congenital spinal abnormalities in pediatric patients, and the concurrence of spinal anomaly diagnoses with other organ system anomalies. Frequencies of congenital spine anomalies were estimated using KID hospital-and-year-adjusted weights. Poisson distribution in contingency tables tabulated concurrence of other congenital anomalies, grouped by body system. RESULTS: Of 12,039,432 patients, rates per 100,000 cases were: 9.1 hemivertebra, 4.3 Klippel-Fiel, 56.3 Chiari malformation, 52.6 tethered cord, 83.4 spina bifida, 1.2 absence of vertebra, and 6.2 diastematomyelia. Diastematomyelia had the highest concurrence of other anomalies: 70.1% of diastematomyelia patients had at least one other congenital anomaly. Next, 63.2% of hemivertebra, and 35.2% of Klippel-Fiel patients had concurrent anomalies. Of the other systems deformities cooccuring, cardiac system had the highest concurrent incidence (6.5% overall). In light of VACTERL's definition of a patient being diagnosed with at least 3 VACTERL anomalies, hemivertebra patients had the highest cooccurrence of ≥3 anomalies (31.3%). With detailed analysis of hemivertebra patients, secundum ASD (14.49%), atresia of large intestine (10.2%), renal agenesis (7.43%) frequently cooccured. CONCLUSIONS: Congenital abnormalities of the spine are associated with serious systemic anomalies that may have delayed presentations. These patients continue to be at a very high, and maybe higher than previously thought, risk for comorbidities that can cause devastating perioperative complications if not detected preoperatively, and full MRI workups should be considered in all patients with spinal abnormalities. LEVEL OF EVIDENCE: Level III.

Shifting Trends in the Epidemiology of Cervical Spine Injuries: An Analysis of 11,822 Patients from the National Electronic Injury Surveillance System over Two Decades.

Cervical spine injuries (CSIs) are heterogeneous in nature and often lead to long-term disability and morbidity. However, there are few recent and comprehensive epidemiological studies on CSI. The objective of this study was to characterize recent trends in CSI patient demographics, incidence, etiology, and injury level. The National Electronic Injury Surveillance System was used to extract data on CSIs from 2002 to 2022. Weighted national estimates of CSI incidence were computed using yearly population estimates interpolated from U.S. census data. Data analysis involved extracting additional information from patient narratives to categorize injury etiology (i.e., fall) and identify CSI level. K-means clustering was performed on cervical levels to define upper versus lower cervical injuries. Appropriate summary statistics including mean with 95% confidence intervals and frequency were reported for age, sex, race, ethnicity, etiology, and disposition. Age between groups was compared using an independent weighted Z-test. All categorical variables were compared using Pearson chi-squared tests with Bonferroni correction for multiple comparisons. Ordinary least squares linear regression was used to quantify the rate of change of various metrics with time. A total of 11,822 patient records met the study criteria. The mean age of patients was 62.4 ± 22.7 years, 52.4% of whom were male and 61.4% of whom were White, 7.4% were Black, 27.8% were not specified, and the remaining comprised a variety of ethnicities. The most common mechanism of CSI was a fall (67.3%). There was a significant increase in the incidence of cervical injuries between 2003 and 2022 (p < 0.001). Unbiased K-means clustering defined upper cervical injuries as C1-C3 and lower cervical injuries as C4-C7. The mean age of patients with upper CSIs was 72.3 ± 19.6, significantly greater than the age of those with lower CSIs (57.1 ± 23.1, p < 0.001). Compared with lower CSI, White patients were more likely to have an upper CSI (67.4% vs. 73.7%; p < 0.001). While Black/African American (7.5% vs. 3.8%) and Hispanic (2.5% vs. 1.0%) patients were more likely to have a lower CSI (p < 0.001). Our study identified a significant increase in the incidence of CSIs over time, which was associated with increasing patient age. Our study detected a pragmatic demarcation of classifying upper injuries as C1-C3 and lower cervical injuries as C4-C7. Upper injuries were seen more often in older, White females who were treated and admitted, and lower injuries were seen more often in young, Black male patients who were released without admission.

Epidemiology of C2 fractures in the United States: A National Electronic Injury Surveillance System database study.

Introduction: C2 fractures are one of the most common traumatic injuries of the cervical spine, with high rates of morbidity and mortality. Current literature on the incidence of C2 fractures is limited to populations outside of the United States (US), prior to 2014, or specific age cohorts. The purpose of this study is to report the incidence rate (IR) of C2 fractures and associated patient demographics in the US between 2002 and 2021 using the National Electronic Injury Surveillance System (NEISS) database. Methods: This study analyzed the NEISS database to identify cases of C2 fractures presenting to US Emergency Departments (EDs) from 2002 to 2021. Annual and overall numbers of fractures, IR, and patient demographics were analyzed. IR is expressed as the number of fractures per 100,000 person-years at risk (PYR). Patients were split into three different age groups for comparison (children and young adults, 0-64 years; older adults, 65-79 years; elderly individuals, 80 + years). Results: A national estimate of n = 72,764 patients (95% confidence interval [CI] = 54,371-91,156) presented to US EDs with a C2 fracture (IR was 1.17/PYR; 95% CI = 0.87-1.46), and elderly individuals had the highest IR overall (IR = 15.9; P < 0.05). The IR of C2 fractures between 2002 and 2021, reported as average annual percent change (AAPC), increased significantly, regardless of age or sex (AAPC = 10.9; 95% CI = 6.3-15.6; P < 0.0001). Conclusion: C2 fractures occur at higher rates than previous years, with especially high IR in elderly individuals. Emphasis of public health efforts toward osteoporosis and coordination difficulties in elderly individuals would likely significantly reduce the overall IR of these injuries.

Demographics, Mechanism of Injury, and Outcomes for Acute Upper and Lower Cervical Spinal Cord Injuries: An Analysis of 470 Patients in the Prospective, Multi-Center, North American Clinical Trials Network Registry.

There is a paucity of data comparing the demographics, mechanism of injury, and outcomes of upper versus lower cervical spinal cord injuries (cSCI). The study objective was to define different clinical manifestations of cSCI. Data were collected prospectively through centers of the North American Clinical Trials Network (NACTN). Data was collected on 470 patients (21% women, mean age 50 years). Cervical vertebral level was analyzed as an ordinal variable to determine a natural demarcation to classify upper versus lower cSCI. For continuous variable analysis, falls were associated with C3 more than C4 vertebral level injuries (60% vs. 42%; p = 0.0126), while motor vehicle accidents were associated with C4 more than C3 (40% vs. 29%; p = 0.0962). Motor International Standards for Neurological Classification of Spinal Cord Injury scores also demonstrated a natural demarcation between C3 and C4, with C3 having higher median American Spinal Injury Association (ASIA) motor scores (40 [4-73] vs. 11 [3-59], p = 0.0227). There were no differences when comparing C2 to C3 nor C4 to C5. Given the significant differences seen between C3 and C4, but not C2 and C3 nor C4 and C5, upper cSCI was designated as C1-C3, and lower cSCI was designated as C4-C7. Compared with a lower cSCI, patients with an upper cSCI were more likely to have a fall as their mechanism of injury (54% vs. 36%; p = 0.0072). Patients with an ASIA C cSCI were likely to have an upper cervical injury: 23% vs. 11% (p = 0.0226). Additionally, patients with an upper cSCI were more likely to have diabetes prior to injury: 37% versus 22%, respectively (p = 0.0084). Lower cSCI were more likely injured through sports (19% vs. 8%, p = 0.0171) and present with ASIA A (42% vs. 25%, p = 0.0186) neurological grade. Patients with lower cSCI were also significantly more likely to have complications such as shock, pulmonary embolism, and pleural effusion. In conclusion, there appears to be a natural demarcation of injury type between C3 and C4. Upper cSCI (C1-C3) was more associated with falls and diabetes, whereas lower cSCI (C4-C7) was more associated with sports, worse ASIA scores, and more complications. Further research will be needed to understand the mechanistic and biological differences between these two groups and whether different treatments may be appropriate for each of these groups.

Interhospital Transfer Delays Care for Spinal Cord Injury Patients: A Report from the North American Clinical Trials Network for Spinal Cord Injury.

Abstract The North America Clinical Trials Network (NACTN) for Spinal Cord Injury (SCI) is a consortium of tertiary medical centers that has maintained a prospective SCI registry since 2004, and it has espoused that early surgical intervention is associated with improved outcome. It has previously been shown that initial presentation to a lower acuity center and necessity of transfer to a higher acuity center reduce rates of early surgery. The NACTN database was evaluated to examine the association between interhospital transfer (IHT), early surgery, and outcome, taking into account distance traveled and site of origin for the patient. Data from a 15-year period of the NACTN SCI Registry were analyzed (years 2005-2019). Patients were stratified into transfers directly from the scene to a Level 1 trauma center (NACTN site) versus IHT from a Level 2 or 3 trauma facility. The main outcome was surgery within 24 hours of injury (yes/no), whereas secondary outcomes were length of stay, death, discharge disposition, and 6-month American Spinal Injury Association Impairment Scale (AIS) grade conversion. For the IHT patients, distance traveled for transfer was calculated by measuring the shortest distance between origin and NACTN hospital. Analysis was performed with Brown-Mood test and chi-square tests. Of 724 patients with transfer data, 295 (40%) underwent IHT and 429 (60%) were admitted directly from the scene of injury. Patients who underwent IHT were more likely to have a less severe SCI (AIS D; p = 0.002), have a central cord injury (p = 0.004), and have a fall as their mechanism of injury (p < 0.0001) than those directly admitted to an NACTN center. Of the 634 patients who had surgery, direct admission to an NACTN site was more likely to result in surgery within 24 hours compared with IHT patients (52% vs. 38%) (p < 0.0003). Median IHT distance was 28 miles (interquartile range [IQR] = 13-62 miles). There was no significant difference in death, length of stay, discharge to a rehab facility versus home, or 6-month AIS grade conversion rates between the two groups. Patients who underwent IHT to an NACTN site were less likely to have surgery within 24 hours of injury, compared with those directly admitted to the Level 1 trauma facility. Although there was no difference in mortality rates, length of stay, or 6-month AIS conversion between groups, patients with IHT were more likely be older with a less severe level of injury (AIS D). This study suggests there are barriers to timely recognition of SCI in the field, appropriate admission to a higher level of care after recognition, and challenges related to the management of individuals with less severe SCI.

Image Quality and Dose Comparison of 3 Mobile Intraoperative Three-Dimensional Imaging Systems in Spine Surgery.

OBJECTIVE: To evaluate radiation exposure and image quality (IQ) for 3 intraoperative imaging systems (Airo TruCT, Cios Spin, O-arm) using varying radiation dose settings in a single cadaveric model. METHODS: Axial images of L4-5 instrumentation were obtained using 3 manufacturer dose protocols for each system. Measurements included scattered radiation dose, subjective and objective IQ, and estimates of patient effective dose (ED). Four images per system were selected at each dose level. Using the Likert scale (1 = best, 5 = worst), 9 reviewers rated the same 36 images. Objective IQ measures included the degree of streak artifacts (lines with incorrect data from metal objects) in each image. A composite figure of merit was derived based on ED and subjective and objective scores. RESULTS: The best subjective IQ scores were 1.44 (Cios Spin medium dose), 1.78 (Cios Spin high dose) and 2.22 (Airo TruCT low dose). The best objective IQ scores were 87.3 (Airo TruCT) and 89.1 (Cios Spin). ED low-dose results in mSv included 1.6 (Airo TruCT), 1.9 (Cios Spin), and 3.3 (O-arm). ED high-dose results in mSv included 4.6 (Cios Spin), 9.7 (Airo TruCT), and 9.9 (O-arm). Scatter radiation measurements for low dose in µGy included 21.9 (Cios Spin), 31.8 (Airo TruCT), and 33.9 (O-arm). Scatter radiation for high dose in µGy included 55.9 (Cios Spin), 104.5 (O-arm), and 200 (Airo TruCT). The best figure of merit score was for the Airo TruCT low dose, followed by Cios Spin medium dose and high dose. CONCLUSIONS: Selection of intraoperative imaging systems requires a greater understanding of the risks and benefits of radiation exposure and IQ.

How to start an awake spine program: Protocol and illustrative cases.

Surgical techniques and technology are steadily improving, thereby expanding the pool of patients amenable for spine surgery. The growing and aging population in the United States further contributes to the increase in spine surgery cases. Traditionally, spine surgery is performed under general anesthesia. However, awake spinal surgery has recently gained traction due to evidence of decreased perioperative risks, postoperative opioid consumption, and costs, specifically in lumbar spine procedures. Despite the potential for improving outcomes, awake spine surgery has received resistance and has yet to become adopted at many healthcare systems. We aim to provide the fundamental steps in facilitating the initiation of awake spine surgery programs. We also present case reports of two patients who underwent awake spine surgery and reported improved clinical outcomes.

Objective Test Scores Throughout Orthopedic Surgery Residency Suggest Disparities in Training Experience.

Diversifying clinical residencies, particularly in fields that are historically dominated by majority male (M/M) cohorts, is critical to improve both the training experiences of residents and the overall physician workforce. Orthopedic surgery in particular has low numbers of females and under-represented minorities (F/URM) at all levels of training and practice. Despite efforts to increase its diversity, this field has become more homogeneous in recent years. To highlight potential barriers and disparate training environments that may contribute to this dynamic, we present 25 years' worth of institutional data on standardized exam performance throughout residency. We report that despite starting residency with standardized exam scores that were comparable to their M/M peers, F/URM orthopedic surgery residents performed progressively worse on Orthopaedic In-service Training Exams throughout residency and had lower first pass rates on the American Board of Orthopedic Surgery Part 1. Given these findings, we propose that disparate performance on standardized test scores throughout residency could identify trainees that may have different experiences that negatively impact their exam performance. Shedding light on these underlying disparities provides opportunities to find meaningful and sustained ways to develop a culture of diversity and inclusion. It may also allow for other programs to identify similar patterns within their training programs. Overall, we propose monitoring test performance on standardized exams throughout orthopedic surgery residency to identify potential disparities in training experience; further, we acknowledge that interventions to mitigate these disparities require a broad, systems wide approach and a firm institutional commitment to reducing bias and working toward sustainable change.

"The eye sees only what the mind is prepared to comprehend": Unrecognized incidental findings on intraoperative computed tomography during spine instrumentation surgery.

BACKGROUND: Intraoperative computed tomography (CT) is becoming more widely utilized in spine fusion surgeries. The use of CT-based image guidance has been shown to increase the accuracy in instrumentation placement and to reduce the rate of reoperation. However, incidental findings that are obvious in retrospect are still missed in spinal fusion surgeries due to the concept of inattentional blindness and surgeons' preoccupation with the main objective of intraoperative CT (i.e. instrumentation accuracy). CASE DESCRIPTION: The first case describes a 60-year-old male who underwent posterior spinal laminectomy and interbody fusions from L2-L5. Intraoperative CT confirmed appropriate placement of hardware. However, when he was transferred out to the care unit and extubated, he developed a severe headache for which the source was confirmed to be a pneumocephalus from durotomy and cerebrospinal fluid leakage on repeat CT. A retrospective review of his intraoperative CT demonstrated the intrathecal air at L5-S1 interlaminar space that was missed on evaluation during surgery. The second case describes a 68-year-old female who was treated with a successful T4 to pelvis instrumentation and fusion with vertebral column resection at T10 confirmed with imaging. Postoperatively, she developed rapidly progressive oxygen desaturation and was found to have a pneumothorax which had been present on the intraoperative imaging. CONCLUSION: This case report of two patients with missed intraoperative findings demonstrates the importance of looking beyond instrumentation placement and evaluating the entire intraoperative CT imaging to find abnormalities that could complicate the patients' postoperative recovery and overall hospital stay.

Management of Acute Traumatic Spinal Cord Injury: A Review of the Literature.

Traumatic spinal cord injury (TSCI) is a debilitating disease that poses significant functional and economic burden on both the individual and societal levels. Prognosis is dependent on the extent of the spinal injury and the severity of neurological dysfunction. If not treated rapidly, patients with TSCI can suffer further secondary damage and experience escalating disability and complications. It is important to quickly assess the patient to identify the location and severity of injury to make a decision to pursue a surgical and/or conservative management. However, there are many conditions that factor into the management of TSCI patients, ranging from the initial presentation of the patient to long-term care for optimal recovery. Here, we provide a comprehensive review of the etiologies of spinal cord injury and the complications that may arise, and present an algorithm to aid in the management of TSCI.

A Prospective Comparison of the Effects of Instrument Tracking on Time and Radiation During Minimally Invasive Lumbar Interbody Fusion.

BACKGROUND: Minimally invasive surgical techniques have resulted in improved patient outcomes. One drawback has been the increased reliance on fluoroscopy and subsequent exposure to ionizing radiation. We have previously shown the efficacy of a novel instrument tracking system in cadaveric and preliminary clinical studies for commonplace orthopedic and spine procedures. In the present study, we examined the radiation and operative time using a novel instrument tracking system compared with standard C-arm fluoroscopy for patients undergoing minimally invasive lumbar fusion. METHODS: The radiation emitted, number of radiographs taken, and time required to complete 2 tasks were recorded between the instrument tracking systems and conventional C-arm fluoroscopy. The studied tasks included placement of the initial dilator through Kambin's triangle during percutaneous lumbar interbody fusion and placement of pedicle screws during both percutaneous lumbar interbody fusion and minimally invasive transforaminal lumbar interbody fusion with or without instrument tracking. RESULTS: A total of 23 patients were included in the analysis encompassing 31 total levels. For the task of placing the initial dilator into Kambin's triangle, an average of 4.21 minutes (2.4 vs. 6.6 minutes; P = 0.002), 15 fluoroscopic images (5.4 vs. 20.5; P = 0.002), and 8.14 mGy (3.3 vs. 11.4; P = 0.011) were saved by instrument tracking. For pedicle screw insertion, an average of 5.69 minutes (3.97 vs. 9.67; P < 0.001), 14 radiographs (6.53 vs. 20.62; P < 0.001), and 7.89 mGy (2.98 vs. 10.87 mGy; P < 0.001) were saved per screw insertion. CONCLUSIONS: Instrument tracking, when used for minimally invasive lumbar fusion, leads to significant reductions in radiation and operative time compared with conventional fluoroscopy.

Acute exertional compartment syndrome of the lumbar paraspinal muscles in a weightlifter. A case report.

BACKGROUND: Compartment syndrome (CS) is a well-known phenomenon in orthopaedics associated with traumatic injury to an extremity or over exertion which ultimately leads to prolonged and elevated intrafascial pressures. CS was initially described by Volkmann in 1881[1]. With any active muscle, there is a transient rise in intrafascial pressure from resting range of approximately 3 mmHg to 7.95 mmHg [2]. When this increase in pressure is too great or not transient, then a subsequent compartment syndrome develops. The consequences of such physiologic imbalance can induce muscle necrosis, nerve damage, vascular compromise, functional deficits, and potentially loss of limb[3,4]. Typical initial presentation of CS includes pain out of proportion to the severity of injury, which is intensified with passive motion of the muscle within the affected fascial compartment.[4] Non musculoskeletal manifestations of CS generally present themselves as the syndrome progresses and can include rhabdomyolysis, myoglobinuria, acute kidney injury, or acute tubular necrosis [4]. These non musculoskeletal manifestations of CS are potential etiologies causing patients to present for treatment [4]. PURPOSE: There have been approximately 20 previous case reports on paraspinal compartment syndrome with a combination of surgical and medical treatments in these patients. We will present a case of paraspinal CS in an avid weightlifter and discuss diagnostic and treatment options surrounding this syndrome. STUDY DESIGN: Case Report. PATIENT SAMPLE: This is a report of a single patient who presented to Duke University Medical Center. METHODS: We report the case of a 29 year old male with paraspinal compartment syndrome who was treated with fasciotomies. This was considered an IRB exempt study by our IRB as such informed consent was not obtained by the patient prior to publication. RESULTS: This patients had resolution of symptoms after surgical intervention which continued through follow up. CONCLUSION: Paraspinal compartment syndrome can be effectively treated with surgical fasciotomy.

Measurement of Spinopelvic Angles on Prone Intraoperative Long-Cassette Lateral Radiographs Predicts Postoperative Standing Global Alignment in Adult Spinal Deformity Surgery.

STUDY DESIGN: Retrospective review from a single institution. OBJECTIVES: To evaluate intraoperative T1-pelvic angle (TPA), T4PA, and T9PA as predictors of postoperative global alignment after adult spinal deformity (ASD) surgery. SUMMARY OF BACKGROUND DATA: Malalignment following adult spinal surgery is associated with disability and correlates with health-related quality of life. Preoperative planning and intraoperative verification are crucial for optimal postoperative outcomes. Currently, only pelvic incidence minus lumbar lordosis (PI-LL) mismatch has been used to assess intraoperative correction. METHODS: Patients undergoing ≥4-level spinal fusion with full-length pre-, intra-, and first postoperative calibrated radiographs were included from a single institution. Alignment measurements were obtained for sagittal vertical axis (SVA), PI-LL, TPA, T4PA, and T9PA. The whole cohort was divided into upper thoracic (UT: UIV > T7) and lower thoracic fusions (LT: UIV < T7). Change was assessed between phases, and a subanalysis was included for UT and LT groups to compare alignment changes for differing extent of proximal fusion in the sagittal plane. RESULTS: Eighty patients (mean 63.4 years, 70% female, mean levels fused 11.9) underwent significant ASD correction (ΔPI-LL = 22.1°; ΔTPA = 13.8°). For all, intraoperative TPA, T4PA, and T9PA correlated with postoperative SVA (range, r = 0.41-0.59), whereas intraoperative PI-LL correlated less (r = 0.38). For UT (n = 49), all spinopelvic angles and LL were similar intraoperative to postoperatively (p > .09). For LT (n = 31), intraoperative and postoperative T9PA and LL were similar (p > .10) but TPA and T4PA differed (p < .02). For UT, all intraoperative and postoperative spinopelvic angles strongly correlated (r = 0.8-0.9). For LT, intraoperative to postoperative T9PA strongly correlated (r = 0.83) and TPA, T4PA, and LL correlated moderately (r = 0.65-0.70). LT trended toward more reciprocal kyphosis postoperatively (8.1° vs. 2.6°; p = .059). CONCLUSIONS: Intraoperative measurements of TPA, T4PA, and T9PA correlated better with postoperative global alignment than PI-LL, demonstrating their utility in confirming alignment goals. When comparing intraoperative to postoperative films, only T9PA was similar in LT whereas all spinopelvic angles were similar in UT. Reciprocal kyphosis in unfused segments of LT fusions may account for difference in TPA and T4PA from intraoperative to postoperative films. LEVEL OF EVIDENCE: Level III.

Patient Dose Comparison for Intraoperative Imaging Devices Used in Orthopaedic Lumbar Spinal Surgery.

BACKGROUND: The aim of this study was to determine the amount of radiation exposure from intraoperative imaging during two-level and four-level lumbar fusions. METHODS: Five imaging systems were studied: multidetector CT (MDCT) scanner (CT A); two mobile CT units (CT B and CT C); a C-arm (D); and fluoroscopy (E). Metal oxide semiconductor field effect transistor dosimeters measured doses at 25 organ locations using an anthropomorphic phantom. A fat-equivalent phantom was used to simulate an obese body mass index (BMI). RESULTS: The effective dose (ED) for C-arm D was estimated using commercial software. The ED for others was computed from the measured mean organ doses. EDs for a normal BMI patient, receiving a four-level fusion, are as follows: CT A (12.00 ± 0.30 mSv), CT B (5.90 ± 0.25 mSv), CT C (2.35 ± 0.44 mSv), C-arm D (0.44 mSv), and fluoroscopy E (0.30 ± 0.3 mSv). The rankings are consistent across all three BMI values except CT C and fluoroscopy E, which peaked in the overweight size because of system limitations. The other machines' ED trended with patient BMI. CONCLUSION: The dose reduction protocols were confirmed according to the manufacturer's specifications. The results of this study emphasize the need for the appropriate selection of the imaging system, especially because the type of device could have a substantial effect on patient radiation risk.

Body mass index predicts risk of complications in lumbar spine surgery based on surgical invasiveness.

BACKGROUND CONTEXT: Obesity as a comorbidity in spine pathology may increase the risk of complications following surgical treatment. The body mass index (BMI) threshold at which obesity becomes clinically relevant, and the exact nature of that effect, remains poorly understood. PURPOSE: Identify the BMI that independently predicts risk of postoperative complications following lumbar spine surgery. STUDY DESIGN/SETTING: Retrospective review of the National Surgery Quality Improvement Program (NSQIP) years 2011-2013. PATIENT SAMPLE: A total of 31,763 patients were undergoing arthrodesis, discectomy, laminectomy, laminoplasty, corpectomy, or osteotomy of the lumbar spine. OUTCOME MEASURES: Complication rates. METHODS: The patient sample was categorized preoperatively by BMI according to the World Health Organization stratification: underweight (BMI <18.5), normal overweight (BMI 20.0-29.9), obesity class 1 (BMI 30.0-34.9), 2 (BMI 35.0-39.9), and 3 (BMI≥40). Patients were dichotomized based on their position above or below the 75th surgical invasiveness index (SII) percentile cutoff into low-SII and high-SII. Differences in complication rates in BMI groups were analyzed by Bonferroni analysis of variance (ANOVA) method. Multivariate binary logistic regression evaluated relationship between BMI and complication categories in all patients and in high-SII and low-SII surgeries. RESULTS: Controlling for baseline difference in SII, Charlson Comorbidity Index (CCI) score, diabetes, hypertension, and smoking, complications significantly increased at a BMI of 35 kg/m2. The odds ratios for any complication (odds ratio [OR] [95% confidence interval {CI}]; obesity 2: 1.218 [1.020-1.455]; obesity 3: 1.742 [1.439-2.110]), infection (obesity 2: 1.335 [1.110-1.605]; obesity 3: 1.685 [1.372-2.069]), and surgical complication (obesity 2: 1.622 [1.250-2.104]; obesity 3: 2.798 [2.154-3.634]) were significantly higher in obesity classes 2 and 3 relative to the normal-overweight cohort (all p<.05). CONCLUSION: There is a significant increase in complications, specifically infection and surgical complications, in patients with BMI≥35 following lumbar spine surgery, with that rate further increasing with BMI≥40.

Normal Age-Adjusted Sagittal Spinal Alignment Is Achieved with Surgical Correction in Adolescent Idiopathic Scoliosis.

STUDY DESIGN: Retrospective analysis. PURPOSE: Our hypothesis is that the surgical correction of adolescent idiopathic scoliosis (AIS) maintains normal sagittal alignment as compared to age-matched normative adolescent population. OVERVIEW OF LITERATURE: Sagittal spino-pelvic alignment in AIS has been reported, however, whether corrective spinal fusion surgery re-establishes normal alignment remains unverified. METHODS: Sagittal profiles and spino-pelvic parameters of thirty-eight postsurgical correction AIS patients ≤21 years old without prior fusion from a single institution database were compared to previously published normative age-matched data. Coronal and sagittal measurements including structural coronal Cobb angle, pelvic incidence, pelvic tilt, thoracic kyphosis, lumbar lordosis, sagittal vertical axis, C2-C7 cervical lordosis, C2-C7 sagittal vertical axis, and T1 pelvic angles were measured on standing full-body stereoradiographs using validated software to compare preoperative and 6 months postoperative changes with previously published adolescent norms. A sub-group analysis of patients with type 1 Lenke curves was performed comparing preoperative to postoperative alignment and also comparing this with previously published normative values. RESULTS: The mean coronal curve of the 38 AIS patients (mean age, 16±2.2 years; 76.3% female) was corrected from 53.6° to 9.6° (80.9%, p<0.01). None of the thoracic and spino-pelvic sagittal parameters changed significantly after surgery in previously hypo- and normo-kyphotic patients. In hyper-kyphotic patients, thoracic kyphosis decreased (p=0.003) with a reciprocal decrease in lumbar lordosis (p=0.01), thus lowering pelvic incidence-lumbar lordosis mismatch mismatch (p=0.009). Structural thoracic scoliosis patients had slightly more thoracic kyphosis than age-matched patients at baseline and surgical correction of the coronal plane of their scoliosis preserved normal sagittal alignment postoperatively. A sub-analysis of Lenke curve type 1 patients (n=24) demonstrated no statistically significant changes in the sagittal alignment postoperatively despite adequate coronal correction. CONCLUSIONS: Surgical correction of the coronal plane in AIS patients preserves sagittal and spino-pelvic alignment as compared to age-matched asymptomatic adolescents.

Comparison of helicopter versus ground transport for the interfacility transport of isolated spinal injury.

BACKGROUND CONTEXT: The use and need of helicopter aeromedical transport systems (HEMSs) in health care today is based on the basic belief that early definitive care improves outcomes. Helicopter aeromedical transport system is perceived to be safer than ground transport (GT) for the interfacility transfer of patients who have sustained spinal injury because of the concern for deterioration of neurologic function if there is a delay in reaching a higher level of care. However, the use of HEMS is facing increasing public scrutiny because of its significantly greater cost and unique risk profile. PURPOSE: The aim of the study was to determine whether GT for interfacility transfer of patients with spinal injury resulted in less favorable clinical outcomes compared with HEMS. STUDY DESIGN/SETTING: Retrospective review of all patients transferred to a Level 1 trauma center. PATIENT SAMPLE: Patients identified from the State Trauma Registry who were initially seen at another hospital with an isolated diagnosis of injury to the spine and then transferred to a Level 1 trauma center over a 2-year period. OUTCOME MEASURES: Neurologic deterioration, disposition from the emergency department, in-hospital mortality, interfacility transfer time, hospital length of stay, nonroutine discharge, and radiographic evidence of worsening spinal injury. METHODS: Patients with International Classification of Diseases, Ninth Revision (ICD-9) codes for injury to the spine were selected and records were reviewed for demographics and injury details. All available spine radiographs were reviewed by an orthopedic surgeon blinded to clinical data and transport type. Chi-square and t tests and multivariate linear and logistic regression models were done using STATA version 10. RESULTS: A total of 274 spine injury patients were included in our analysis, 84 (31%) of whom were transported by HEMS and 190 (69%) by GT. None of the GT patients had any deterioration in neurologic examination nor any detectable alteration in the radiographic appearance of their spine injury attributable to the transportation process. Helicopter aeromedical transport system resulted in significantly less transfer time with an average time of 80 minutes compared with 112 minutes with GT (p<.001). Ultimate disposition included 175 (64%) patients discharged to home, 15 (5%) expired patients, and 84 (31%) discharged to extended care facilities. After adjusting for patient age and Injury Severity Score, the use of GT was not a significant predictor of in-hospital mortality (odds ratio, 1.4; 95% confidence interval, 0.3-5), hospital length of stay (11.2+1.3 vs. 9.5+0.8 days, p=.3), or nonroutine discharge (odds ratio, 1.1; 95% confidence interval, 0.5-2.2). CONCLUSIONS: Ground transport for interfacility transfer of patients with spinal injury appears to be safe and suitable for patients who lack other compelling reasons for HEMS. A prospective analysis of transportation mode in a larger cohort of patients is needed to verify our findings.