McGregor's slope and slope of line of sight: two surrogate markers for Chin-Brow vertical angle in the setting of cervical spine pathology.

BACKGROUND CONTEXT: Chin-Brow Vertical Angle (CBVA) is not routinely measured on radiographs even though it is a strong assessor of horizontal gaze. STUDY DESIGN: Retrospective cohort study of patients with full-body stereoradiographs and a primary cervical diagnosis at the time of presentation. PURPOSE: Assess the utility of McGregor's Slope (McGS) and Slope of Line of Sight (SLS) as surrogate markers for the CBVA in cervical spine pathology. METHODS: A retrospective review of patients with full-body stereoradiographs was performed. Patients were ≥18 years of age with a primary cervical diagnosis. Analysis of CBVA, McGS, and SLS was conducted as markers of horizontal gaze. Sagittal alignment was characterized by: pelvic tilt (PT), pelvic incidence minus lumbar lordosis (PI-LL), T1-pelvic angle (TPA), sagittal vertical axis (SVA), T2-T12 thoracic kyphosis, C2-C7 SVA (cSVA), C2-C7 Cervical lordosis, T1-Slope minus Cervical Lordosis (TS-CL), and C2-Slope (C2S). A subgroup analysis was performed in patients with cervical deformity. Independent sample t tests and paired t tests compared radiographic alignment. Pearson correlations characterized linear relationships. Linear regression analysis identified relationships between the parameters. RESULTS: In all, 329 patients were identified with primary cervical spine diagnoses. Chin-Brow Vertical Angle was visible in 171 patients (52.0%), McGS in 281 (85.4%), and SLS in 259 (78.7%). Of the 171 patients with visible CBVA, the mean CBVA was 2.30±7.7, mean McGS was 5.02±8.1, and mean SLS was -1.588±2.03. Chin-Brow Vertical Angle strongly correlated with McGS (r=0.83) and SLS (r=0.89) with p<.001. McGregor's Slope positively correlated with SLS (r=0.89, p=.001). CONCLUSIONS: This study demonstrates that McGS and SLS serve as strong, positive correlates for CBVA. The reported mean differences between these measurements provide a useful conversion, broadening CBVA's use as a radiographic assessment of horizontal gaze.

Traumatic Fracture of the Pediatric Cervical Spine: Etiology, Epidemiology, Concurrent Injuries, and an Analysis of Perioperative Outcomes Using the Kids' Inpatient Database.

BACKGROUND: The study aimed to characterize trends in incidence, etiology, fracture types, surgical procedures, complications, and concurrent injuries associated with traumatic pediatric cervical fracture using a nationwide database. METHODS: The Kids' Inpatient Database (KID) was queried. Trauma cases from 2003 to 2012 were identified, and cervical fracture patients were isolated. Demographics, etiologies, fracture levels, procedures, complications, and concurrent injuries were assessed. The t-tests elucidated significance for continuous variables, and χ2 for categoric values. Logistic regressions identified predictors of spinal cord injury (SCI), surgery, any complication, and mortality. Level of significance was P < .05. RESULTS: A total of 11 196 fracture patients were isolated (age, 16.63 years; male, 65.7%; white, 65.4%; adolescent, 55.4%). Incidence significantly increased since 2003 (2003 vs 2012, 2.39% vs 3.12%, respectively), as did Charlson Comorbidity Index (CCI; 2003 vs 2012, 0.2012 vs 0.4408, respectively). Most common etiology was motor vehicle accidents (50.5%). Infants and children frequently fractured at C2 (closed: 43.1%, 32.9%); adolescents and young adults frequently fractured at C7 (closed: 23.9%, 26.5%). Upper cervical SCI was less common (5.8%) than lower cervical SCI (10.9%). Lower cervical unspecified-SCI, anterior cord syndrome, and other specified SCIs significantly decreased since 2003. Complications were common (acute respiratory distress syndrome, 7.8%; anemia, 6.7%; shock, 3.0%; and mortality, 4.2%), with bowel complications, cauda equina, anemia, and shock rates significantly increasing since 2003. Concurrent injuries were common (15.2% ribs; 14.4% skull; 7.1% pelvis) and have significantly increased since 2003. Predictors of SCI included sports injury and CCI. Predictors of surgery included falls, sports injuries, CCI, length of stay, and SCI. CCI, SCIs, and concurrent injuries were predictors of any complication and mortality, all (P < .001). CONCLUSIONS: Since 2003, incidence, complications, concurrent injuries, and fusions have increased. CCI, SCI, falls, and sports injuries were significant predictors of surgical intervention. Decreased mortality and SCI rates may indicate improving emergency medical services and management guidelines. LEVEL OF EVIDENCE: III. CLINICAL RELEVANCE: Clinicians should be aware of increased case complexity in the onset of added perioperative complications and concurrent injuries. Cervical fractures resultant of sports injuries should be scrutinized for concurrent SCIs.

Trends in Treatment of Scheuermann Kyphosis: A Study of 1,070 Cases From 2003 to 2012.

STUDY DESIGN: Retrospective review of KID Inpatient Database (KID) from 2003, 2006, 2009, and 2012. OBJECTIVES: The aim of this study was to evaluate the impact of advances in spinal surgery on patient outcomes in the treatment of Scheuermann kyphosis (SK). SUMMARY OF BACKGROUND DATA: SK is one of the most common causes of back pain in adolescents. Trends in diagnoses and surgical treatment and approach to SK have not been well described. METHODS: SK patients aged 0-20 years in KID were identified by ICD-9 code 732.0. KID-supplied year- and hospital-trend weights were used to establish prevalence. Patient demographics, surgical details, and outcomes were analyzed with analysis of variance. RESULTS: A total of 1,070 SK patients were identified (33.2% female), with increasing incidence of SK diagnosed from 2003 to 2012 (3.6-7.5 per 100,000, p < .001). The average age of operative patients was 16.1±2.0 years and did not change (16.27-16.06 years, p = .905). The surgical rate has not changed over time (72.8%-72.8%, p = .909). Overall, 96.3% of operative patients underwent fusion, with 82.2% of cases spanning ≥4 levels; in addition, 8.6% underwent an anterior-only surgery, 74.6% posterior-only, and 13.6% combined approach. From 2003 to 2012, rates of posterior-only surgeries increased (62.4%-84.4%, p < .001) whereas the rate of combined-approach surgeries decreased (37.6%-8.8%, p < .001). Overall complication rates for SK surgeries have decreased (2003: 20.9%; 2012: 11.9%, p = .029). Concurrently, the rate of ≥4-level fusions has increased (43.5%-89.6%, p < .001), as well as the use of Smith-Peterson (7.8%-23.6%, p < .001) and three-column osteotomies (0.0%-2.7%, p = .011). In subanalysis comparing posterior to combined approaches, complication rates were significantly different (posterior: 9.88%, combined: 19.46%, p = .005). Patients undergoing a combined approach have a longer length of stay (LOS) than patients undergoing a posterior-only approach (7.8 vs. 5.6 days, p < .001). CONCLUSIONS: Despite unchanged demographics and operative rates in SK, there has been a shift from combined to isolated posterior approaches, with a concurrent increase in levels treated. A combined approach was associated with increased complication rates, LOS, and total charges compared to isolated approaches. Awareness of these inherent differences is important for surgical decision making and patient education. LEVELS OF EVIDENCE: Level III.

Rates of Mortality in Lumbar Spine Surgery and Factors Associated With Its Occurrence Over a 10-Year Period: A Study of 803,949 Patients in the Nationwide Inpatient Sample.

BACKGROUND: The rate of mortality in surgical procedures involving the lumbar spine has historically been low, and as a result, there has been difficulty providing accurate quantitative mortality rates to patients in the preoperative planning phase. Awareness of these mortality rates is essential in reducing postoperative complications and improving outcomes. Additionally, mortality rates can be influenced by procedure type and patient profile, including demographics and comorbidities. The purpose of this study is to assess rates and risk factors associated with mortality in surgical procedures involving the lumbar spine using a large national database. METHODS: The Nationwide Inpatient Sample database was reviewed from 2003 to 2012. A total of 803,949 patients age 18 years or older were identified by ICD-9CM procedure codes for spinal fusion or decompression of the lumbar spine. Mortality was stratified based on type of procedure (simple or complex fusion, decompression), patient demographics and comorbidities, and in-hospital complications. Binary logistic regression was used to identify the risk of death while controlling for comorbidities, race, sex, and procedure performed. Significance was defined as P < .05 differences relative to the overall cohort. RESULTS: Mortality for all patients requiring surgery of the lumbar spine was 0.13%. Mortality based on procedure type was 0.105% for simple fusions, 0.321% for complex fusions, and 0.081% for decompression only. Increased mortality was observed demographically in patients who were male (odds ratio [OR]: 1.75; 95% confidence interval [CI]: 1.51-2.03), black (OR: 1.40; CI: 1.10-1.79), ages 65-74 (OR: 1.46; CI: 1.25-1.70), and age 75+ (OR: 2.70; CI: 2.30-3.17). Comorbidities associated with the greatest increase in mortality were mild (OR: 10.04; CI: 7.76-13.01) and severe (OR: 26.47; CI: 16.03-43.70) liver disease and congestive heart failure (OR: 4.57; CI: 3.77-5.53). The complications with the highest mortality rates were shock (OR: 20.67; CI: 13.89-30.56) and pulmonary embolism (OR: 20.15; CI: 14.01-29.00). CONCLUSIONS: From 2003 to 2012, the overall mortality rate in 803,949 lumbar spine surgery patients was 0.13%. Risk factors that were significantly associated with increased mortality rates were male gender, black race, and ages 65-74 and 75+. Comorbidities associated with an increased mortality rate were mild and severe liver disease and congestive heart failure. Inpatient complications with the highest mortality rates were shock and pulmonary embolism. These findings can be helpful to surgeons providing preoperative counseling for patients considering elective lumbar procedures and for allocating resources to treat and prevent perioperative complications leading to mortality. LEVEL OF EVIDENCE: 3.

Psoas Morphology Differs between Supine and Sitting Magnetic Resonance Imaging Lumbar Spine: Implications for Lateral Lumbar Interbody Fusion.

STUDY DESIGN: Retrospective radiological review. PURPOSE: To quantify the effect of sitting vs supine lumbar spine magnetic resonance imaging (MRI) and change in anterior displacement of the psoas muscle from L1-L2 to L4-L5 discs. OVERVIEW OF LITERATURE: Controversy exists in determining patient suitability for lateral lumbar interbody fusion (LLIF) based on psoas morphology. The effect of posture on psoas morphology has not previously been studied; however, lumbar MRI may be performed in sitting or supine positions. METHODS: A retrospective review of a single-spine practice over 6 months was performed, identifying patients aged between 18-90 years with degenerative spinal pathologies and lumbar MRIs were evaluated. Previous lumbar fusion, scoliosis, neuromuscular disease, skeletal immaturity, or intrinsic abnormalities of the psoas muscle were excluded. The anteroposterior (AP) dimension of the psoas muscle and intervertebral disc were measured at each intervertebral disc from L1-L2 to L4-L5, and the AP psoas:disc ratio calculated. The morphology was compared between patients undergoing sitting and/or supine MRI. RESULTS: Two hundred and nine patients were identified with supine-, and 60 patients with sitting-MRIs, of which 13 patients had undergone both sitting and supine MRIs (BOTH group). A propensity score match (PSM) was performed for patients undergoing either supine or sitting MRI to match for age, BMI, and gender to produce two groups of 43 patients. In the BOTH and PSM group, sitting MRI displayed significantly higher AP psoas:disc ratio compared with supine MRI at all intervertebral levels except L1-L2. The largest difference observed was a mean 32%-37% increase in sitting AP psoas:disc ratio at the L4-L5 disc in sitting compared to supine in the BOTH group (range, 0%-137%). CONCLUSIONS: The psoas muscle and the lumbar plexus become anteriorly displaced in sitting MRIs, with a greater effect noted at caudal intervertebral discs. This may have implications in selecting suitability for LLIF, and intra-operative patient positioning.

Radiological severity of hip osteoarthritis in patients with adult spinal deformity: the effect on spinopelvic and lower extremity compensatory mechanisms.

PURPOSE: Sagittal spinal deformity (SSD) patients utilize pelvic tilt (PT) and their lower extremities in order to compensate for malalignment. This study examines the effect of hip osteoarthritis (OA) on compensatory mechanisms in SSD patients. METHODS: Patients ≥ 18 years with SSD were included for analysis. Spinopelvic, lower extremity, and cervical alignment were assessed on standing full-body stereoradiographs. Hip OA severity was graded by Kellgren-Lawrence scale (0-4). Patients were categorized as limited osteoarthritis (LOA: grade 0-2) and severe osteoarthritis (SOA: grade 3-4). Patients were matched for age and T1-pelvic angle (TPA). Spinopelvic [sagittal vertical axis (SVA), T1-pelvic angle, thoracic kyphosis (TK), pelvic tilt (PT), lumbar lordosis (LL), pelvic incidence minus lumbar lordosis (PI-LL), T1-spinopelvic inclination (T1SPi)] and lower extremity parameters [sacrofemoral angle, knee angle, ankle angle, posterior pelvic shift (P. Shift), global sagittal axis (GSA)] were compared between groups using independent sample t test. RESULTS: 136 patients (LOA = 68, SOA = 68) were included in the study. SOA had less pelvic tilt (p = 0.011), thoracic kyphosis (p = 0.007), and higher SVA and T1Spi (p < 0.001) than LOA. SOA had lower sacrofemoral angle (p < 0.001) and ankle angle (p = 0.043), increased P. Shift (p < 0.001) and increased GSA (p < 0.001) compared to LOA. There were no differences in PI-LL, LL, knee angle, or cervical alignment (p > 0.05). CONCLUSIONS: Patients with coexisting spinal malalignment and SOA compensate by pelvic shift and thoracic hypokyphosis rather than PT, likely as a result of limited hip extension secondary to SOA. As a result, SOA had worse global sagittal alignment than their LOA counterparts. These slides can be retrieved under Electronic Supplementary Material.