Faculty Bibliography

STUDY DESIGN: Retrospective. OBJECTIVE: This study assessed the feasibility of combining Oswestry and Neck Disability Index (ODI and NDI) into 1 shorter "Total Disability Index" (TDI) from which reconstructed scores could be computed. SUMMARY OF BACKGROUND DATA: ODI and NDI are not pure assessments of disability related to back and neck, respectively. Because of similarities/redundancies of questions, ODI scores may be elevated in neck-pain patients and the converse is true for NDI in back-pain patients. METHODS: Spine patients completed ODI and NDI, and complaints were recorded as back pain (BP), neck pain (NP), or both (BNP). Questionnaire scores were compared across cohorts via descriptives and Spearman (rho) correlations. In exploring the feasibility of merging ODI/NDI, TDI was constructed from 9 ODI and 5 NDI items. Extracting questions from TDI, reconstructed 9-item rODI and 10-item rNDI indices were formed and compared with true ODI/NDI. RESULTS: There were a total of 1207 patients: 741 BP, 134 NP, and 268 BNP. Mean ODI was 37 +/- 21 and mean NDI was 32 +/- 21. Patients with concurrent BP and NP had significantly more disability. Seventy-eight patients of 134 (58%) patients with NP only had at least "moderate disability" by ODI and 297 of 741 (40%) patients with back pain only, had at least "moderate disability" by NDI. ODI versus NDI correlation was rho = 0.755; ODI versus reconstructed rODI correlated at rho = 0.985, and NDI versus reconstructed rNDI correlated at rho = 0.967 (P < 0.01). CONCLUSION: Elevated ODI/NDI scores in patients with isolated complaints show that disability in 1 region affects scores on both surveys. This study constructed a 14-item TDI that represents every domain of ODI/NDI with exception of ODI "Sex Life." From this TDI, reconstructed scores correlated near perfectly with true scores. TDI provides a more global assessment of spinal disability and is a questionnaire that reduces the time burden to patients. The TDI allows for simultaneous assessment of back, neck, and global spinal disability. LEVEL OF EVIDENCE: 2.

BACKGROUND: Pre-donation of autologous blood prior to spine fusion for adolescent idiopathic scoliosis (AIS) has been used in deformity surgery. The effect of pre-donation on pre-operative hematocrit (Hct) remains debated. Multiple factors may influence pre-operative Hct including intravascular volume status, patient factors, and timing of pre-operative blood donation. The purpose of this study was to determine if pre-donation significantly lowers pre-incision Hct in AIS patients. METHODS: A retrospective cohort study of a Level-1 prospective randomized trial was conducted. 125 patients from the homogeneous population were included. AIS patients undergoing a posterior only spinal fusion for AIS were separated into two groups based on their pre-operative blood donation history. Demographic variables, pre-incision Hct, and transfusion rates were compared between the two groups using the Student's T-test. RESULTS: Pre-donation and non pre-donation groups had 28 and 97 patients, respectively. Pre-donation group was 75% female (21F, 7M) and non pre-donation group was 78% female (76F, 21M). There was no difference between pre-donation and non pre-donation groups in mean age (15.6 +/- 2.2 vs 14.8 +/- 2.2, p = 0.081), BMI (23.1 +/- 4.2 vs 21.7 +/- 5.3, p = 0.219), and pre-incision Hct (32.8 +/- 3.4 vs 33.8 +/- 3.1, p = 0.628). The overall transfusion rates were equivalent (32.1+/- 48.0% vs 25.8 +/- 44.0%, p = 0.509), however, the rate of allogenic transfusion for the pre-donation group was significantly lower (3.6 +/- 18.9% vs 25.8 +/- 44.0%, p = 0.011). CONCLUSIONS: This study supports the use of pre-donation for AIS, without a significant drop in pre-incision Hct. Patients that donate are also much less likely to be exposed to allogenic blood. There may be a surgeon bias to recommend pre-donation in patients with a larger BMI and older age. Future studies are needed from a larger population of patients including those with non-AIS pathology. LEVEL OF EVIDENCE: Level III.

INTRODUCTION: Wound infections following spinal surgery place a high toll on both the patient and the healthcare system. Although several large series studies have examined the incidence and distribution of spinal wound infection, the applicability of these studies varies greatly since nearly every study is either retrospective and/or lacks standard inclusion criteria for defining surgical site infection. To address this void, we present results from prospectively gathered thoracolumbar spine surgery data for which the Centers for Disease Control (CDC) criteria were stringently applied to define a surgical site infection (SSI). METHODS: A prospective randomized trial of 314 patients who underwent multilevel thoracolumbar spinal surgery with instrumentation followed by postoperative drain placement was completed (Takemoto et al., 2015). The trial consisted of two antibiotic arms: one for 24-hours, and the other for the duration of the drain; no differences were found between the arms. All infections meeting CDC criteria for SSI were included. RESULTS: A total of 40 infections met CDC criteria for SSI, for an overall incidence of 12.7%. Of these, 20 (50%) were culture-positive. The most common organism was Staphylococcus aureus (4 total: methicillin-sensitive=2; methicillin-resistant=2), followed by coagulase-negative Staphylococcus (3 cases), Propionibacterium acnes and Escherichia coli (2 cases each). Six infections grew multiple organisms, most commonly involving coagulase-negative staphylococcus and enterococcus. CONCLUSIONS: Our findings indicate that thoracolumbar SSI occurs at the higher end of the range cited in the literature (2-13%), which is largely based on retrospective data not subjected to the inclusivity of SSI as defined by the CDC. The three most common organisms in our analysis (S. aureus, P. acnes, E. coli) are consistent with previous reports. Staphylococcus aureus continues to be the most common causative organism and continued vigilance and searching for preventive measures need to be a high priority. This study provides Level I evidence.

BACKGROUND: Hip osteoarthritis often coexists with adult spinal deformity, an abnormality in which sagittal spinopelvic malalignment is present. Debate exists whether to perform spinal realignment correction or total hip arthroplasty first. Hip extension and pelvic tilt are important compensatory mechanisms in the setting of sagittal spinopelvic malalignment and change after spinal realignment. We performed this study to evaluate the effect that the spinal realignment surgical procedure has on acetabular anteversion. METHODS: This study is a retrospective review of a multicenter, prospective, consecutive database of patients with adult spinal deformity who underwent surgical spinal realignment. Only patients who already had undergone a total hip arthroplasty prior to the spinal realignment procedure were retained for analysis. Patients were excluded if they had insufficient imaging or large-head, metal-on-metal bearings or they had undergone revision total hip arthroplasty in the study period. Acetabular anteversion was calculated via the ellipse method on a standing, posterior-anterior, 90-cm radiograph with a well-centered pelvis. Anteversion was measured preoperatively and at six weeks or three months after the spinal realignment procedure. Spinopelvic parameters measured included pelvic incidence, pelvic tilt, sacral slope, lumbar lordosis, T1 pelvic angle, sagittal vertical axis, T1-spinopelvic inclination, and thoracic kyphosis. RESULTS: Forty-one hips (thirty-three patients) were identified. Acetabular anteversion significantly reduced (p < 0.001) after spinal correction by mean change of -4.96 degrees (range, -22.32 degrees to +2.36 degrees ). The change in anteversion correlated with the changes in sagittal pelvic orientation (0.828 for the pelvic tilt, -0.757 for the sacral slope, and -0.691 for the lumbar lordosis) and global spinopelvic alignment (0.579 for the sagittal vertical axis and 0.585 for the T1 pelvic angle). Regression analysis revealed that anteversion decreased by 1 degrees for each of the following spinopelvic parameter changes (p < 0.001): 1.105 degrees for spinopelvic tilt, 1.032 degrees for sacral slope, and 3.163 degrees for lumbar lordosis. CONCLUSIONS: Patients with spinopelvic malalignment had a high prevalence of excessively anteverted acetabular components. Sagittal spinal correction following total hip arthroplasty resulted in reduced acetabular anteversion, which may have implications for stability. Changes in anteversion are most closely related to changes in pelvic tilt in an almost one-to-one ratio. LEVEL OF EVIDENCE: Therapeutic Level IV. See Instructions for Authors for a complete description of levels of evidence.

BACKGROUND CONTEXT: Numerous studies have demonstrated poorer outcomes in patients with Workers' Compensation (WC) when compared to those without WC following treatment of various of health conditions including spine disorders. It is thus important to consider compensation status when assessing treatment outcomes in spine surgery. However, reported strengths of association have varied significantly (1.31-7.22). PURPOSE: The objective of this study was to evaluate the association of unsatisfactory outcomes on compensation status in spine surgery patients. STUDY DESIGN/SETTING: Meta-analysis PATIENT SAMPLE: Not applicable OUTCOME MEASURE: Demographics, type of surgery, country, follow-up time, patient satisfaction, return to work and non-union events. METHODS: Both prospective and retrospective studies that compared outcomes between compensated and non-compensated patients in spine surgery were included. Two independent investigators extracted outcome data. The meta-analysis was performed using Revman software. Random effects model was used to calculate risk ratio (RR, 95% confidence interval (CI) for dichotomous variables. There are no conflicts of interest to report among the authors, and no funding was received for this study. RESULTS: 31 studies (13 prospective; 18 retrospective) with a total of 3567 patients were included in the analysis. Follow-up time varied from 4 months to 10 years. 12 studies involved only decompression; the rest were fusion. Overall RR of an unsatisfactory outcome was 2.12 [1.74, 2.58; p<0.001] in patients with WC when compared to those without WC after surgery. RR of an unsatisfactory outcome in patients with WC, compared to those without, was 2.09 [1.38, 3.17]; p<0.01 among studies from Europe and Australia and 2.14 [1.48, 2.60]; p<0.01 among US studies. RR of decompression-only procedures was 2.53 [1.85, 3.47]; p<0.01 and 1.79 [1.45, 2.21]; p<0.01 for fusion. 43% (209/491) of patients with WC returned to work versus 17% (214/1250) of those without WC (RR 2.07 [1.43, 2.98]; p<0.001). 25 % (74/292) and 13.5% (39/287) of patients had non-union in the compensated and non-compensated groups, respectively. This was not statistically significant (RR 1.33 [0.92, 1.91]; p=0.07). CONCLUSIONS: Workers' compensation patients have a two-fold increased risk of an unsatisfactory outcome compared to non-compensated patients after surgery. This association was consistent when studies were grouped by country or procedure. Compensation status must be considered in all surgical intervention studies.

OBJECT Adult spinal deformity (ASD) surgery is known for its high complication rate. This study examined the impact of obesity on complication rates, infection, and patient-reported outcomes in patients undergoing surgery for ASD. METHODS This study was a retrospective review of a multicenter prospective database of patients with ASD who were treated surgically. Patients with available 2-year follow-up data were included. Obesity was defined as having a body mass index (BMI) >/= 30 kg/m2. Data collected included complications (total, minor, major, implant-related, radiographic, infection, revision surgery, and neurological injury), estimated blood loss (EBL), operating room (OR) time, length of stay (LOS), and patient-reported questionnaires (Oswestry Disability Index [ODI], Short Form-36 [SF-36], and Scoliosis Research Society [SRS]) at baseline and at 6 weeks, 1 year, and 2 years postoperatively. The impact of obesity was studied using multivariate modeling, accounting for confounders. RESULTS Of 241 patients who satisfied inclusion criteria, 175 patients were nonobese and 66 were obese. Regression models showed that obese patients had a higher overall incidence of major complications (IRR 1.54, p = 0.02) and wound infections (odds ratio 4.88, p = 0.02). Obesity did not increase the number of minor complications (p = 0.62), radiographic complications (p = 0.62), neurological complications (p = 0.861), or need for revision surgery (p = 0.846). Obesity was not significantly correlated with OR time (p = 0.23), LOS (p = 0.9), or EBL (p = 0.98). Both groups experienced significant improvement overtime, as measured on the ODI (p = 0.0001), SF-36 (p = 0.0001), and SRS (p = 0.0001) questionnaires. However, the overall magnitude of improvement was less for obese patients (ODI, p = 0.0035; SF-36, p = 0.0012; SRS, p = 0.022). Obese patients also had a lower rate of improvement over time (SRS, p = 0.0085; ODI, p = 0.0001; SF-36, p = 0.0001). CONCLUSIONS This study revealed that obese patients have an increased risk of complications following ASD correction. Despite these increased complications, obese patients do benefit from surgical intervention; however, their improvement in health-related quality of life (HRQL) is less than that of nonobese patients.

STUDY DESIGN: Retrospective review of a prospectively collected database. OBJECTIVE: This study compares patient demographics, incidence of comorbidities, procedure-related complications, and mortality following primary vs. revision adult spinal deformity surgerySummary of Background Data. While adult spinal deformity (ASD) surgery has been extensively investigated, no previous study has provided nationwide estimates of patient characteristics and procedure-related complications for primary vs. revision spinal deformity surgery comparatively. METHODS: Nationwide Inpatient Sample data collected between 2001 and 2010 was analyzed. Discharges with procedural codes for anterior and/or posterior thoracic and/or lumbar spinal fusion and refusion were included for patients aged 25+ and 4+ levels fused with any diagnoses specific for scoliosis. Patient demographics, comorbidity and procedure-related complications incidence were determined for primary vs. revision cohorts. Multivariate analysis reported as (OR [95% CI]). RESULTS: Discharges for 9133 primary and 850 revision cases were identified. Patients differed on the basis of demographic and hospital data. Average comorbidity indices for the cohorts were similar (p = 0.580), as was in-hospital mortality (p = 0.163). The incidence of procedure-related complications was higher for the revision cohort (46.96% vs. 71.97%, p = 0.001). The mean hospital course for the revision cohort was longer (6.37 vs. 7.13 days, p<0.0001). Revisions had an increased risk of complications involving the nervous system (1.34[1.10-1.6]), hematoma/seroma formation (2.31[1.92-2.78]), accidental vessel or nerve puncture (1.44[1.29-1.61]), wound dehiscence (2.18[1.48-3.21]), post-op infection (3.10[2.50-3.85]) and ARDS complications (1.43[1.28-1.60]). The primary cohort had a decreased risk for GI (0.65[0.55-0.76]) and GU complications (0.71[0.51-0.99]). CONCLUSIONS: Relative to primary cases, those undergoing revision correction of spinal deformity have a higher risk of many procedure-related complications with a longer hospital course despite similar baseline comorbidity burden and in-hospital mortality rate. This study provides clinically useful data for surgeons to educate patients at risk for morbidity and mortality and direct future research to improve outcomes.

BACKGROUND CONTEXT: In transforminal lumbar interbody fusion (TLIF), bilateral pedicle screw/rod fixation has been shown to increase fusion construct stability and decrease posterior instrumentation stress when compared to unilateral instrumentation. However, unilateral instrumentation is beneficial over bilateral instrumentation due to shorter operative time, less blood loss and reduced implant costs. It is important to note though that comparative studies between unilateral and bilateral instrumentation in TLIF have shown similar patient satisfaction outcomes, they are limited in their evaluation of complications due to small sample size of studies. PURPOSE: The purpose of this meta-analysis was to evaluate complications, and fusion rates between unilateral and bilateral instrumentation in TLIF. STUDY DESIGN/SETTING: Meta-analysis of randomized controlled trials. PATIENT SAMPLE: 549 patients undergoing one- and multi-levels TLIF. OUTCOME MEASURES: Outcome data extracted included fusion rates, health related quality of life (HRQoL) scores and complications including cage migration, dural tear, deep vein thrombosis, surgical site infections and screw failures. METHODS: Randomized controlled trials (RCTs) that compared outcomes between unilateral and bilateral pedicle screw instrumentation in single- and multi-level TLIF were identified. Data extraction was performed by two independent reviewers. Meta-analysis was performed using RevMan 5. Weighted standardized mean difference (SMD) and odds ratio (OR) 95% confidence intervals (CI) were calculated. Jadad scoring was used to assess bias of included studies. RESULTS: Eight RCTs were included, having a total of 549 patients (267 unilateral/282 bilateral). Minimum follow-up ranged from 3 to 24 months. Bias-assessment scores varied between 0 and 3 indicating high-moderate bias-risk. Six involved open TLIF procedures and two involved minimally invasive TLIF. There was no difference between postoperative Health Related Quality of Life scores in the unilateral and bilateral instrumented groups (SMD = 0.29; [-0.77, 0.18]; p=0.69). There was no statistical difference in fusion rates (OR = 0.47; 95% CI [0.21, 1.04], p=0.68), with 88.9% and 95.0% achieving fusion in the unilateral and bilateral groups, respectively. The unilateral cohort had a higher incidence of cage migration (5.6%) when compared to the bilateral cohort (2.5%), approaching statically significant (p=0.07). Other complications which included dural tears, deep vein thrombosis, surgical site infections and screw failures were comparable between the groups. CONCLUSIONS: Fusion rates and complications appear comparable in unilateral and bilateral instrumentation in TLIF. Though not statistically significant, there was higher incidence of cage migration in the unilateral cohort

BACKGROUND CONTEXT: Osteoarthritis of the hip often co-exists with sagittal spinal deformity (SSD). Clinical manifestations overlap, and debate exists whether spinal deformity correction or total hip arthroplasty (THA) should be performed first. Hip extension and pelvic tilt are important compensatory mechanisms in SSD. In theory, spinal deformity correction may cause reciprocal changes in acetabular position. PURPOSE: To assess the changes in acetabular anteversion (AV) as a result of SSD correction, and to quantify the relationship between changes in AV and spino-pelvic parameters. STUDY DESIGN/SETTING: Retrospective analysis of a multicenter prospective database of adult spinal deformity patients. PATIENT SAMPLE: SSD patients who underwent surgical realignment were reviewed and included if they had a THA on baseline radiographs. Patients were excluded if they had large metal-on-metal bearings or revision THA in the study period. OUTCOME MEASURES: Radiographic anteversion of the acetabular component was measured pre- and postoperatively, and compared to the changes in spino-pelvic parameters as result of SSD correction. METHODS: Acetabular anteversion (AV) was calculated via the ellipse method (Lewinneck) on a standing PA 36" X-ray image with a wellcentered pelvis to avoid projectional measurement error. AV was measured preoperatively, and on the 6-week or 3-month postoperative X-ray study. Spino-pelvic parameters were measured including pelvic incidence (PI), pelvic tilt (PT), sacral slope (SS), lumbar lordosis (LL), T1-pelvic angle (TPA), sagittal vertical axis (SVA), truncal tilt (T1SPi) and thoracic kyphosis (TK). Correlation coefficient and linear regression was performed to assess their relationships. RESULTS: Forty-one hips (33 patients) were identified. AV reduces after SSD correction by a mean 4.9degree (range +2 to -23). The change in AV was significantly correlated with the changes in PT (R=0.80), SS (R=-0.693), LL (R=-0.682), PI-LL (R=0.7237), SVA (R=0.561) and TPA (R=0.696). There was a weak correlation with TK and T1SPi. AV was decreased by 1degree for each of the following iatrogenic changes in spino-pelvic parameters (p<0001): 1.1degree PT, -1degree SS, 3.2degree LL, 1.67degree TPA and -11mm SVA. Thirty (73%) of acetabular components had a preoperative AVoutside the Lewinneck "safe zones." Twenty-eight of these 30 were excessively anteverted as a result of increased preoperative pelvic tilt. Postoperatively, 49% of patients still had an AV outside the safe zone, with 65% of these having residual pelvic tilt>20degree. Correction of SSD moved one acetabulum (2.4%) from a safe to unsafe AV. CONCLUSIONS: Correction of SSD results in reduction in AV, with potential implications for THA stability. SSD correction, when indicated, should be performed prior to THA to enable accurate acetabular positioning and minimize potential for dislocation. This study provides an algorithm for the sequence of THA and SSD correction in the patient with concominant pathologies