Faculty Bibliography

Background/UNASSIGNED:Hospital-acquired venous thromboembolisms (HA-VTE) are a significant source of morbidity and mortality in spine surgery patients. The purpose of this study was to review HA-VTE rates at our institution and evaluate the prevalence of known risk factors in patients who developed HA-VTE among both neurosurgical and orthopedic spine surgeries. Methods/UNASSIGNED: < .05. Results/UNASSIGNED: < .001). Conclusions/UNASSIGNED:The overall HA-VTE rate at our institution was 0.94% (0.61% orthopedic, 1.87% neurosurgery). In patients who sustained VTE, neurosurgical patients had higher rates of active cancer and age >60 years, and orthopedic patients had higher EBL and rates of anterior-posterior surgery. This highlights the different patient populations between the 2 departments and the need for individualized thromboprophylaxis regimens. Level of Evidence/UNASSIGNED:4.

PURPOSE/OBJECTIVE:Predictors of long-term opioid usage in TLIF patients have not been previously explored in the literature. We examined the effect of pre-operative narcotic use in addition to other predictors of the pattern and duration of post-operative narcotic usage. METHODS:We conducted a retrospective cohort study at a single academic institution of patients undergoing a one- or two-level primary TLIF between 2014 and 2017. Total oral morphine milligram equivalents (MMEs) for inpatient use were calculated and used as the common unit of comparison. RESULTS: = 0.547, specificity 95%, sensitivity 58%) demonstrated that a psychiatric or chronic pain diagnosis (OR 3.95, p = 0.013, 95% CI 1.34-11.6), pre-operative opioid use (OR 8.65, p < 0.001, 95% CI 2.59-29.0), ASA class (OR 2.95, p = 0.025, 95% CI 1.14-7.63), and inpatient total MME (1.002, p < 0.001, 95% CI 1.001-1.003) were positive predictors of prolonged opioid use at 6-month follow-up, while inpatient muscle relaxant use (OR 0.327, p = 0.049, 95% CI 0.108-0.994) decreased the probability of prolonged opioid use. Patients in the pre-operative opioid use group had a significantly higher rate of opioid usage at 6 weeks (79% vs. 46%, p < 0.001), 3 months (51% vs. 14%, p < 0.001), and 6 months (40% vs. 5%, p < 0.001). CONCLUSIONS:Pre-operative opioid usage is associated with higher total inpatient opioid use and a significantly higher risk of long-term opiate usage at 6 months. Approximately 40% of pre-operative narcotic users will continue to consume narcotics at 6-month follow-up, compared with 5% of narcotic-naïve patients. These slides can be retrieved under Electronic Supplementary Material.

Study Design/UNASSIGNED:Retrospective cohort study. Objective/UNASSIGNED:To investigate radiological differences in lumbar disc herniations (herniated nucleus pulposus [HNP]) between patients receiving microscopic lumbar discectomy (MLD) and nonoperative patients. Methods/UNASSIGNED:test and chi-square analyses compared differences in the groups, binary logistic regression analysis determined odds ratios (ORs), and decision tree analysis compared the cutoff values for risk factors. Results/UNASSIGNED:< .01). Conclusion/UNASSIGNED:Patients who underwent MLD treatment had significantly different axial HNP area, frequency of caudal migration, magnitude of cephalad/caudal migration, and disc herniation MRI signal compared to patients with nonoperative treatment.

BACKGROUND:Selective fusion of double curves in patients with scoliosis is considered to spare fusion levels. In 2011, we studied the lumbosacral takeoff angle, defined as the angle between the center-sacral vertical line and a line through the centra of S1, L5, and L4. The lumbosacral takeoff angle was shown to moderately correlate with the lumbar Cobb angle, and a predictive equation was developed to predict the lumbar Cobb angle after selective fusions. The purposes of the present study were to validate that equation in a separate cohort and to assess differences in outcomes following selective and nonselective fusion. METHODS:Patients with Lenke 1B, 1C, 3B, or 3C curve patterns undergoing fusion (both selective and nonselective) with pedicle screw constructs and a minimum of 2 years of follow-up were included. Selective fusion was defined as a lowest level of fixation cephalad to or at the apex of the lumbar curve. To validate the previously derived equation, we used this data set and analysis of variance to check for differences between the actual and calculated postoperative lumbar Cobb angles. Pearson correlation, multiple linear regression, and t tests were used to explore relationships and differences between the selective and nonselective fusion groups. RESULTS:The mean calculated postoperative lumbar Cobb angle (and standard deviation) (22.35° ± 3.82°) was not significantly different from the actual postoperative lumbar Cobb angle (21.08° ± 7.75°), with an average model error of -1.268° (95% confidence interval, -2.649° to 0.112°). The preoperative lumbar Cobb angle was larger in patients with deformities that were chosen for nonselective fusion (50.2° versus 38.9°; p < 0.001). Performing selective fusion resulted in a 3.5° correction of the lumbosacral takeoff angle (p < 0.001), whereas nonselective fusion resulted in a 9.3° correction (p < 0.001). CONCLUSIONS:The lumbosacral takeoff angle can be used to predict the residual lumbar Cobb angle and may be used by surgeons to aid in the decision between selective and nonselective fusion. The change in the lumbosacral takeoff angle following selective fusion is small. Improvement in the lumbosacral takeoff angle and coronal balance is greater in association with nonselective fusion. LEVEL OF EVIDENCE/METHODS:Therapeutic Level III. See Instructions for Authors for a complete description of levels of evidence.

Metabolic syndrome is a clustering of clinical findings defined in the literature including hypertension, high glucose, abdominal obesity, high triglyceride, and low high-density lipoprotein cholesterol levels. The purpose of this study was to assess perioperative outcomes in patients undergoing spine fusion surgery with (MetS) and without (no-MetS) a history of metabolic syndrome. Included: Patients ≥18 yrs old undergoing spine fusion procedures diagnosed with MetS components with BL and 1-year follow-up were isolated in a single-center database. Patients in the two groups were propensity score matched for levels fused. 250 spine fusion patients (58 yrs, 52.2%F, 39.0 kg/m²) with an average CCI of 1.92 were analyzed. 125 patients were classified with MetS (60.2 yrs, 52%F, CCI: 3.2). MetS patients were significantly older (p = 0.012). MetS patients underwent significantly more open (Met-S: 78.4% vs No-MetS: 45.6%, p < 0.001) and posterior approached procedures (Met-S: 60.8% vs No-MetS: 47.2%, p = 0.031). Mean operative time: 272.4 ± 150 min (MetS: 288.1 min vs. no-MetS: 259.7; p = 0.089). Average length of stay: 4.6 days (MetS: 5.27 vs no-MetS: 3.95; p = 0.095). MetS patients had more post-operative complications (29.6% vs. 18.4%; p = 0.038), specifically neuro (6.4% vs 2.4%), pulmonary (4% vs. 1.6%), and urinary (4.8% vs 2.4%) complications. Binary logistic regression analyses found that MetS was an independent risk factor for post-operative complications (OR: 1.865 [1.030-3.375], p = 0.040). With longer surgeries and greater open-exposure types, MetS patients were at greater risk for complications, despite controlling for total number of levels fused. Surgeons should be aware of the increased threat to spine surgery patients with metabolic syndrome in order to optimize surgical decision-making.

BACKGROUND CONTEXT/BACKGROUND:Obesity has risen to epidemic proportions within the United States. As the rates of obesity have increased, so has its prevalence among patients undergoing adult spinal deformity (ASD) surgery. The effect of obesity on the cost efficiency of corrective procedures for ASD has not been effectively evaluated. PURPOSE/OBJECTIVE:To investigate differences in cost efficiency of ASD surgery for patients stratified by body mass index (BMI). STUDY DESIGN/SETTING/METHODS:Retrospective review of a single center ASD database. PATIENT SAMPLE/METHODS:505 ASD patients OUTCOME MEASURES: Complications, revisions, costs, EuroQol-5D (EQ5D), quality adjusted life years (QALYS), cost per QALY. METHODS:ASD patients (scoliosis≥20°, SVA≥5cm, PT≥25°, or TK ≥60°) ≥18, undergoing ≥4 level fusions were included. Patients were stratified into NIH-defined obesity groups based on their preoperative BMI: underweight 18.5< (U), normal 18.5-24.9 (N), overweight 25.0-29.9 (O), obese I 30.0-34.9 (OI), obese II 35.0-39.9 (OII), and obesity class III 40.0 + (OIII). Total surgery costs for each ASD obesity group were calculated. Costs were calculated using the PearlDiver database, which reflects both private insurance and Medicare reimbursement claims. Overall complications (CC) and major complications (MCC) were assessed according to CMS. DEFINITIONS/BACKGROUND:QALYs and cost per QALY for obesity groups were calculated using an annual 3% discount up to life expectancy (78.7 years). RESULTS:In all, 505 patients met inclusion criteria. Baseline demographics and surgical details were: age 60.8 ± 14.8, 67.6% female, BMI 28.8 ± 7.30, 81.0% posterior approach, 18% combined approach, 10.1 ± 4.2 levels fused, op time 441.2 ± 146.1 minutes, EBL 1903.8 ± 1594.7 cc, LOS 8.7 ± 10.7 days. There were 17 U, 154 N patients, 151 O patients, 100 OI, 51 OII, and 32 OIII patients. Revision rates by obesity group were: 0% U, 3% N patients, 3% O patients, 5% OI, 4% OII, and 6% for OIII patients. The total surgery costs by obesity group were: $48,757.86 U, $49,688.52 N, $47,219.93 O, $50,467.66 OI, $51,189.47 OII, and $53,855.79 OIII. In an analysis of patients with baseline and 1Y EQ5D follow up, the cost per QALY by obesity group was: $153,737.78 U, $229,222.37 N, $290,361.68 O, $493,588.47 OI, $327,876.21 OII, and $171,680.00 OIII. If that benefit was sustained to life expectancy, the cost per QALY was $8,588.70 U, $12,805.72 N, $16,221.32 O, $27,574.77 OI, $18,317.11 OII, and $9,591.06 for OIII. CONCLUSIONS:Among adult spinal deformity patients, those with BMIs in the obesity I, obesity II, or obesity class III range had more expensive total surgery costs. When assessing 1 year cost per quality adjusted life year, obese patients had costs 32% higher than non-obese patients ($224,440.61 vs. $331,048.23). Further research is warranted on the utility of optimizing modifiable preoperative health factors for patients undergoing corrective adult spinal deformity surgery.

OBJECTIVE:Investigate the differences in spine surgery cost for metabolic syndrome patients. METHODS:Included: Patients ≥18, undergoing fusion. Patients were divided into cervical, thoracic, and lumbar groups based on their upper instrumented vertebrae (UIV). Metabolic syndrome patients (MetS) included: BMI >30, DM, dyslipidemia, and HTN. Propensity score matching for invasiveness between Non-MetS and MetS used to assess cost differences. Total surgery costs for MetS and non-MetS ASD patients were compared. QALYs and cost per QALY for UIV groups were calculated. RESULTS:312 invasiveness matched surgeries met inclusion criteria. Baseline demographics and surgical details: age 57.7 ± 14.5, 54% female, BMI 31.1 ± 6.6, 17% anterior approach, 70% posterior approach, 13% combined approach, 3.8 ± 4.1 levels fused. The average costs of surgery between MetS and non-Mets patients was $60,579.30 vs. $52,053.23 (p<0.05). When costs were compared between UIV groups, MetS patients had higher cervical and thoracic surgery costs ($23,203.43 vs $19,153.43, $75,230.05 vs. $65,746.16, all p<0.05) and lower lumbar costs ($31,775.64 vs. $42,643.37, p<0.05). However, the average cost per QALY at 1Y was $639,069.32 for MetS patients and $425,840.30 for non-Mets patients (p<0.05). At life expectancy, the cost per QALY was $45,456.83 vs. $26,026.84 (p<0.05). CONCLUSIONS:When matched by invasiveness, metabolic syndrome patients had an average 16.4% higher surgery costs, 50% higher costs per quality adjusted life years at 1 year, and 75% higher cost per quality adjusted life years at life expectancy. Further research is needed on the possible utility of reducing comorbidities in preoperative patients.

BACKGROUND:Spinal degeneration and lumbar flatback deformity can decrease recruitment of protective posterior pelvic tilt when sitting, leading to anterior impingement and increased instability. We aim at analyzing regional and global spinal alignment between sitting and standing to better understand the implications of spinal degeneration and flatback deformity for hip arthroplasty. METHODS:Spinopelvic parameters of patients with full-body sitting-standing stereoradiographs were assessed: lumbar lordosis (LL), spinopelvic tilt (SPT), pelvic incidence minus LL (PI-LL), sagittal vertical axis (SVA), and T1 pelvic angle (TPA). Lumbar spines were classified as normal, degenerative (disc height loss >50%, facet arthropathy, or spondylolisthesis), or flatback (degenerative criteria and PI-LL >10°). Independent t-tests and analysis of variance were used to analyze alignment differences between groups. RESULTS:After propensity matching for age, sex, and hip osteoarthritis grade, 57 patients per group were included (62 ± 11 years, 58% female). Mean standing and sitting SPT, PI-LL, SVA, and TPA increased along the spectrum of disease severity. Increasing severity of disease was associated with decreasing standing and sitting LL. The flatback group demonstrated the greatest sitting SPT, PI-LL, SVA, and TPA. The amount of sitting-to-standing change in SPT, LL, PI-LL, SVA, and TPA decreased along the spectrum of disease severity. CONCLUSION/CONCLUSIONS:Spinal degeneration and lumbar flatback deformity both significantly decrease lower lumbar spine mobility and posterior SPT from standing to sitting in a stepwise fashion. The demonstrated hypomobility in flatback patients likely serves as a pathomechanism for the previously observed increased risk of dislocation in total hip arthroplasty.