Faculty Bibliography

BACKGROUND: The maintenance of horizontal gaze is an essential function of upright posture and global sagittal spinal alignment. Horizontal gaze is classically measured by the chin-brow vertical angle (CBVA), which is not readily measured on most lateral spine radiographs. OBJECTIVE: To evaluate relations between CBVA and the slope of the line of sight, the slope of McGregor's line (McGS), and Oswestry Disability Index. METHODS: Patients were identified from a single center database of 531 spine patients who underwent full-body EOS x-rays. Correlations between CBVA, the slope of the line of sight, and McGS were assessed. Using a quadratic regression with Oswestry Disability Index and CBVA, windows of low disability were identified. Comparison of sagittal spinopelvic parameters was carried out between patients with "ascending gaze" and "neutral position." RESULTS: Three hundred three patients were included (74% female, mean age 54.8 years, body mass index 26.6 +/- 6.0 kg/m). CBVA strongly correlated with the slope of the line of sight (r = 0.996) and McGS (r = 0.862). Regression studies between Oswestry Disability Index and CBVA yielded a range of values corresponding to low disability (-4.7 degrees to 17.7 degrees). Similarly, a low disability range for the slope of the line of sight (-5.1 degrees to 18.5 degrees) and McGS (-5.7 degrees to 14.3 degrees) was computed. Patients with "ascending gaze" had a worse spinopelvic alignment than "neutral position" patients. CONCLUSION: The slope of the line of sight and McGS correlated strongly with CBVA and can be used as surrogate measures. The range of values for these measures corresponding to low disability was identified. These values can be used as a general guideline to assess alignment for diagnostic purposes. Cervical compensatory mechanism may modify the natural head position in sagittally misaligned patients. ABBREVIATIONS: CBVA, chin-brow vertical angleHRQoL, health-related quality of lifeMcGS, slope of McGregor's lineODI, Oswestry Disability IndexSLs, slope of the line of sight.

BACKGROUND: High-quality studies that compare operative and nonoperative treatment for adult spinal deformity (ASD) are needed. OBJECTIVE: To compare outcomes of operative and nonoperative treatment for ASD. METHODS: This is a multicenter, prospective analysis of consecutive ASD patients opting for operative or nonoperative care. Inclusion criteria were age >18 years and ASD. Operative and nonoperative patients were propensity matched with the baseline Oswestry Disability Index, Scoliosis Research Society-22r, thoracolumbar/lumbar Cobb angle, pelvic incidence-to-lumbar lordosis mismatch (PI-LL), and leg pain score. Analyses were confined to patients with a minimum of 2 years of follow-up. RESULTS: Two hundred eighty-six operative and 403 nonoperative patients met the criteria, with mean ages of 53 and 55 years, 2-year follow-up rates of 86% and 55%, and mean follow-up of 24.7 and 24.8 months, respectively. At baseline, operative patients had significantly worse health-related quality of life (HRQOL) based on all measures assessed (P < .001) and had worse deformity based on pelvic tilt, pelvic incidence-to-lumbar lordosis mismatch, and sagittal vertical axis (P /=1 complications. CONCLUSION: Operative treatment for ASD can provide significant improvement of HRQOL at a minimum 2-year follow-up. In contrast, nonoperative treatment on average maintains presenting levels of pain and disability. ABBREVIATIONS: ASD, adult spinal deformityHRQOL, health-related quality of lifeLL, lumbar lordosisMCID, minimal clinically important differenceNRS, numeric rating scaleODI, Oswestry Disability IndexPI, pelvic incidenceSF-36, Short Form-36SRS-22r, Scoliosis Research Society-22rSVA, sagittal vertical axis.

STUDY DESIGN: A retrospective subgroup analysis was performed on surgically treated patients from the lumbar spinal stenosis (SpS) arm of the Spine Patient Outcomes Research Trial (SPORT), randomized and observational cohorts. OBJECTIVE: To identify risk factors for reoperation in patients treated surgically for SpS and compare outcomes between patients who underwent reoperation with those that did not. SUMMARY OF BACKGROUND DATA: SpS is one of the most common indications for surgery in the elderly; however, few long-term studies have identified risk factors for reoperation. METHODS: A post-hoc subgroup analysis was performed on patients from the SpS arm of the Spine Patient Outcomes Research Trial (SPORT), randomized and observational cohorts. Baseline characteristics were analyzed between reoperation and no reoperation groups using univariate and multivariate analysis on data eight years post-operation. RESULTS: Of the 417 study patients, 88% underwent decompression only, 5% non-instrumented fusion and 6% instrumented fusion. At the 8 year follow up, the reoperation rate was 18%; 52% of reoperations were for recurrent stenosis or progressive spondylolisthesis, 25% for complication or other reason and 16% for new condition. Of patients who underwent a reoperation, 42% did so within 2 yrs, 70% within 4 years and 84% within 6 years. Patients who underwent reoperation were less likely to have presented with any neurological deficit (43% reop vs. 57% no reop, p = 0.04). Patients improved less at follow-up in the re-operation group (p < 0.001). CONCLUSION: In patients undergoing surgical treatment for SpS, the reoperation rate at eight year follow-up was 18%. Patients with a reoperation were less likely to have a baseline neurological deficit. Patients who did not undergo reoperation had better patient reported outcomes at eight year follow up compared to those who had repeat surgery. LEVEL OF EVIDENCE: 2.

STUDY DESIGN: A systematic review. OBJECTIVE: To systematically review the previous literature regarding revision surgery for real recurrent lumbar disk herniation. SUMMARY OF BACKGROUND DATA: "Real" recurrent lumbar disk herniation means the presence of herniated disk material at the same level and side as the primary disk herniation. If conservative treatment fails, revision surgery, a major concern, is indicated. It is important for both patients and spine surgeons to understand epidemiology trends and outcomes of revision surgery for real recurrent lumbar disk herniation (real-RLDH). METHODS: The electronic databases PubMed, the Cochrane library, and EMBASE were queried for English articles regarding revision surgery for real-RLDH, published between January 1980 and May 2014. The incidence, interval between primary and revision surgery, risk factors, surgery type, complications, and clinical outcomes of revision surgery for real-RLDH were summarized. RESULTS: The reported incidence of revision surgery, specifically for real-RLDH, lies between 1.4% and 11.4%. The complication rate is reported between 0% and 34.6%, with dural tear being the most common complication. Previous studies revealed that satisfactory or successful clinical outcome was achieved in 60%-100% of patients after revision surgery for real-RLDH. Several studies reported similar clinical outcomes between primary and revision surgery. CONCLUSIONS: The incidence of revision surgery for real-RLDH is relatively low. It is essential to pay careful attention to prevent a dural tear. Patients may expect clinical outcomes similar to those following primary discectomy. LEVEL OF EVIDENCE: Level III.

DESIGN:Retrospective review. OBJECTIVE:To evaluate gender-related differences in compensatory recruitment to progressive sagittal malalignment. SUMMARY OF BACKGROUND DATA:Recent research has elucidated compensatory mechanisms recruited in response to sagittal malalignment, but gender-specific differences in compensatory recruitment patterns is unknown. METHODS:Single-center study of patients with full body x-rays. A female group was propensity matched by age, body mass index (BMI), and pelvic incidence (PI) to a male group. Patients were then stratified into five groups of progressive PI-lumbar lordosis (LL) mismatch (<0°, 0°-10°, 10°-20°, 20°-30°, >30°). Differences between PI-LL groups were assessed with analysis of variance, and between genders by unpaired t test. Knee flexion to pelvic tilt (PT) ratio was computed and compared between genders. Multivariate regression to develop predictive models for PT was performed for each gender, first with spinopelvic parameters and subsequently with inclusion of lower limb parameters. RESULTS:A total of 942 patient visits were included: 471 females (mean age 54 years, BMI 27, PI 51°) and 471 males (mean age 52 years, BMI 27, PI 51°). At the lowest level of malalignment, females had greater PT and less knee flexion. With progressive malalignment, females continued to exhibit a pattern of greater pelvic retroversion and less knee flexion compared to males. Hip extension was higher in females with progressive PI-LL mismatch groups. Both genders progressively recruited knee flexion and pelvic retroversion with increased PI-LL mismatch, except that at the higher PI-LL mismatch groups, only males continued to recruit knee flexion (all p < .05). Inclusion of lower limbs in the regression for PT markedly improved correlation coefficients for females but not for males. CONCLUSIONS:With progressive sagittal malalignment, men recruit more knee flexion and women recruit more pelvic tilt and hip extension. Knee flexion is a possible mechanism to gain pelvic tilt for females whereas for males, knee flexion is an independent compensatory mechanism.

With the advent of new instrumentation and better imaging techniques that allowed less tissue trauma compared with traditional open procedures, while providing adequate or enhanced visualization of the pathologic site and based upon the successful experience of outpatient spine surgery to assist early ambulation, the trend and evolution toward ''minimal access'' or minimally invasive spine surgery began to develop with greater intensity. Many surgical techniques have flourished with the promise of delivering a safe and efficient alternative, including chemonucleolysis, manual percutaneous discectomy (MPD), automated percutaneous lumbar discectomy (APLD), and percutaneous lumbar laser discectomy (PLLD). Unfortunately, most of these techniques have been demonstrated to be inefficient with high complication rates. Only modifications of the original open discectomy in which direct visualization of the disc is obtained through either microscopic or endoscopic techniques have proven to be successful. This review outlines the historical journey that has inspired the development of these techniques and delineates the progressive clinical experience gained from their advent.

OBJECT Previous forceplate studies analyzing the impact of sagittal-plane spinal deformity on pelvic parameters have demonstrated the compensatory mechanisms of pelvis translation in addition to rotation. However, the mechanisms recruited for this pelvic rotation were not assessed. This study aims to analyze the relationship between spinopelvic and lower-extremity parameters and clarify the role of pelvic translation. METHODS This is a retrospective study of patients with spinal deformity and full-body EOS images. Patients with only stenosis or low-back pain were excluded. Patients were grouped according to T-1 spinopelvic inclination (T1SPi): sagittal forward (forward, > 0.5 degrees ), neutral (-6.3 degrees to 0.5 degrees ), or backward (< -6.3 degrees ). Pelvic translation was quantified by pelvic shift (sagittal offset between the posterosuperior corner of the sacrum and anterior cortex of the distal tibia), hip extension was measured using the sacrofemoral angle (SFA; the angle formed by the middle of the sacral endplate and the bicoxofemoral axis and the line between the bicoxofemoral axis and the femoral axis), and chin-brow vertical angle (CBVA). Univariate and multivariate analyses were used to compare the parameters and correlation with the Oswestry Disability Index (ODI). RESULTS In total, 336 patients (71% female; mean age 57 years; mean body mass index 27 kg/m(2)) had mean T1SPi values of -8.8 degrees , -3.5 degrees , and 5.9 degrees in the backward, neutral, and forward groups, respectively. There were significant differences in the lower-extremity and spinopelvic parameters between T1SPi groups. The backward group had a normal lumbar lordosis (LL), negative SVA and pelvic shift, and the largest hip extension. Forward patients had a small LL and an increased SVA, with a large pelvic shift creating compensatory knee flexion. Significant correlations existed between lower-limb parameter and pelvic shift, pelvic tilt, T-1 pelvic angle, T1SPi, and sagittal vertical axis (0.3 < r < 0.8; p < 0.001). ODI was significantly correlated with knee flexion and pelvic shift. CONCLUSIONS This is the first study to describe full-body alignment in a large population of patients with spinal pathologies. Furthermore, patients categorized based on T1SPi were found to have significant differences in the pelvic shift and lower-limb compensatory mechanisms. Correlations between lower-limb angles, pelvic shift, and ODI were identified. These differences in compensatory mechanisms should be considered when evaluating and planning surgical intervention for adult patients with spinal deformity.

BACKGROUND: Preoperative anemia is a well-established risk factor for short-term mortality in patients undergoing non-cardiac surgery, but appropriate thresholds for transfusion remain uncertain. The objective of this study was to determine long-term outcomes associated with anemia, hemorrhage and red blood cell transfusion in patients undergoing non-cardiac surgery. METHODS: We performed a long-term follow-up study of consecutive subjects undergoing hip, knee, and spine surgery between November 1, 2008 and December 31, 2009. Clinical data were obtained from administrative and laboratory databases, and retrospective record review. Pre-operative anemia was defined as baseline hemoglobin <13 g/dL for men and <12 g/dL for women. Hemorrhage was defined by ICD-9 coding. Data on long-term survival were queried from the Social Security Death Index (SSDI) database. Logistic regression models were used to identify factors associated with long-term mortality. RESULTS: 3,050 subjects underwent orthopedic surgery. Pre-operative anemia was present in 17.6% (537) of subjects, hemorrhage occurred in 33 (1%), and 766 (25%) received >/=1 red blood cell transfusion. Over 9,015 patient-years of follow up, 111 deaths occurred. Anemia (HR 3.91, CI 2.49 - 6.15) and hemorrhage (HR 5.28, CI 2.20 - 12.67) were independently associated with long-term mortality after multivariable adjustment. Red blood cell transfusion during the surgical hospitalization was associated with long-term mortality (HR 3.96, CI 2.47 - 6.34), which was attenuated by severity of anemia (no anemia [HR 4.39], mild anemia [HR 2.27], and moderate/severe anemia [HR 0.81], P for trend 0.0015). CONCLUSIONS: Preoperative anemia, perioperative bleeding and red blood cell transfusion are associated with increased mortality at long-term follow up after non-cardiac surgery. Strategies to minimize anemia and bleeding should be considered for all patients and restrictive transfusion strategies may be advisable. Further investigation into mechanisms of these adverse events is warranted.

Adult spinal deformity (ASD) is a complex disease comprised of different deformity types that often involve the entire spine. Accurate assessment of ASD requires a thorough radiographic evaluation of both the spine and pelvis, including concomitant assessment of the cervical, thoracic, and lumbar spine, as well as the femoral heads and pelvis. Radiographic measurements should include assessment of regional alignment (including lumbar lordosis, thoracic kyphosis, C2-C7 lordosis), global alignment (including C7 SVA, C2-C7 SVA, and T1 pelvic angle), and measures of pelvic compensation and morphology (pelvic tilt, pelvic incidence, T1 slope, and C2-pelvic tilt). Together these radiographic parameters provide important information regarding how the ASD patient maintains upright posture and correlate with the patient's pain and disability. ASD surgical planning must integrate regional, global, and pelvic compensatory/morphologic parameters to adequately correct deformity and thereby provide pain relief and improve function. Radiographic classifications for cervical and thoracolumbar deformities have been developed that utilize the regional and global measures of spinal deformity that are most predictive of patient-reported pain and function. These classifications are aimed to standardize the assessment of ASD to aid in clinical management and to facilitate future research on the evaluation and treatment of ASD.

STUDY DESIGN: Retrospective review. OBJECTIVE: This study follows the inpatient-stay administrative data that were collected for a cohort of thousands of patients who had spine fusion surgery in the state of New York. We sought to examine adult spinal deformity (ASD) for reoperation events with and without the use of bone morphogenetic protein-2 (BMP). SUMMARY OF BACKGROUND DATA: Randomized controlled trials have suggested that BMP may increase the likelihood of solid arthrodesis in spinal surgery. This would imply fewer reoperations for pseudarthrosis, but small cohort sizes are inadequate to monitor these events. METHODS: The 2008-2011 New York State Inpatient Database was queried using International Classification of Diseases, Ninth Revision, Clinical Modification codes. Patients age 21 years and older with a diagnosis of scoliosis and an index fusion of greater than 2 spinal motion segments were included. Patient identifiers and linkage variables were used to identify revisits. The relative risk of reoperation was calculated. The use of BMP at the initial inpatient stay was used to define the 2 cohorts for relative risk assessment. RESULTS: A total of 3751 patients of ASD were identified in 2008. The use of BMP at the initial visit was performed at a rate of 37.6% for ASD. For posterior fusion cases longer than 8 levels, the rate of reoperation for a pseudarthrosis was 23.4%. For ASD fusions greater than 8 levels, the rate of reoperation for pseudarthrosis after using BMP at the index surgery was 5% and 33.9% when BMP was not used, a relative risk of 7.5 (P < 0.001). CONCLUSION: Using relevant inhospital patient records from the New York State Inpatient Sample, we found a 7.5-fold decrease in the risk of reoperation for pseudarthrosis after long fusions when using BMP. Decreased reoperation rates are caused by the improved fusion with the use of BMP. If subsequent unnecessary hospitals stays can be avoided, the economics of BMP use should be reexamined. LEVEL OF EVIDENCE: 4.