Faculty Bibliography

Low back and neck pain are among the top contributors for years lived with disability, causing patients to seek substantial non-operative and operative care. Intervertebral disc herniation is one of the most common spinal pathologies leading to low back pain. Patient comorbidities and other risk factors contribute to the onset and magnitude of disc herniation. Spine fusions have been the treatment of choice for disc herniation, due to the conflicting evidence on conservative treatments. However, re-operation and costs have been among the main challenges. Novel technologies including cage surface modifications, biologics, and 3D printing hold a great promise. Artificial disc replacement has demonstrated reduced rates of adjacent segment degeneration, need for additional surgery, and better outcomes. Non-invasive biological approaches are focused on cell-based therapies, with data primarily from preclinical settings. High-quality comparative studies are needed to evaluate the efficacy and safety of novel technologies and biological therapies.

STUDY DESIGN:This is a retrospective cohort study. OBJECTIVE:This study's objective was to determine whether perioperative invasive vascular catheter placement, independent of comorbid conditions, modified the risk of postoperative infection in lumbar spine surgery. SUMMARY OF BACKGROUND DATA:Infection is a risk inherent to lumbar spine surgery, with overall postoperative infection rates of 0.86%-8.5%. Patients experiencing postoperative infection have higher rates of mortality, revision surgeries, pseudarthrosis, and worsening pain and disability. METHODS:Data were collected for patients undergoing lumbar spine surgery between January 2007 and October 2015 with records in the nationwide Humana private insurance database. Patients receiving fusion, laminectomy, and discectomy were followed for 3 months from the date of surgery for surgical site infection (SSI), 6 months for subsequent incision and drainage (I&D), and 1 year for vertebral osteomyelitis (VO). Risk factors investigated included central venous catheter and arterial-line placement. RESULTS:Analysis of 114,259 patient records showed an overall SSI rate of 3.2% within 1 month and 4.5% within 3 months, overall vertebral osteomyelitis rate of 0.82%-0.83% within 1 year, and overall I&D rate of 2.8% within 6 months. Patients receiving a first-time invasive vascular catheter on the day of surgery were more likely to experience SSI within 1 month [risk ratios (RR), 2.5, 95% confidence interval (CI): 2.3-2.7], SSI within 3 months (RR, 2.4; 95% CI: 2.3-2.7), osteomyelitis within 1 year (RR, 4.2-4.3; 95% CI: 3.7-4.5), and undergo an I&D within 6 months (RR, 1.9; 95% CI: 1.8-2.0). These trends were consistent by procedure type and independent of the patient's weighted comorbidity index score (Charlson Comorbidity Index). CONCLUSIONS:Perioperative invasive vascular catheterization was significantly associated with an increased the risk of postoperative infections in lumbar spine surgery, independent of a patient's concomitant comorbidities. Therefore, in patients with an indication for invasive catheterization, surgeons should consider risks and benefits of surgery carefully. LEVEL OF EVIDENCE:Level III.

STUDY DESIGN/METHODS:Retrospective kinematic MRI (kMRI) study. OBJECTIVE:To evaluate the dynamic changes of thoracic anterior and posterior space available for cord (SAC), and thoracic spinal cord in the dural sac in three positions. SETTING/METHODS:Expert MRI, Bellflower California; and University of Southern California, in Los Angeles, USA. METHODS:A total of 118 patients (66 males and 52 females, mean age ( ± SD) of 45.6 ± 10.6 years) who underwent thoracic spine kMRI were evaluated from T4-5 to T11-12 in flexion, neutral, and extension positions. The anterior SAC, posterior SAC, and mid-sagittal thoracic cord diameter were measured at each level from T4-5 to T11-12. Inter- and intraobserver agreements were analyzed. RESULTS:The anterior SAC was significantly narrower in flexion position compared with other positions at T8-9 to T11-12 levels (p < 0.01). The T8-9 level had significantly wider posterior SAC in flexion and extension positions compared with the neutral position (p < 0.005). However, the posterior SAC at T9-10 was narrower in extension than the neutral position (p = 0.002). Thoracic spinal cord diameter significantly increased in flexion position when compared with the neutral position at T8-9, T9-10, and T11-12 levels (p < 0.005). CONCLUSIONS:Thoracic spinal cord had dynamic changes with positions. In flexion position, the thoracic cord at T8-9 and below tended to move anteriorly, getting closer to the vertebral body and intervertebral disc. The mid-sagittal diameter of the thoracic cord increased in flexion position at the levels below T8-9. In the presence of lesions in anterior epidural space, the risk of spinal cord compression is higher in flexion position, especially at levels below T8-9.

STUDY DESIGN:This was a retrospective database study. OBJECTIVE:The aim of this study was to use a large sample to accurately determine risk factors and rates of neurological complications in patients undergoing commonly performed lumbar spine surgeries. SUMMARY OF BACKGROUND DATA:Damage to neurological structures and failed back surgery syndrome (FBSS) are among the most feared complications of lumbar spine surgery. Despite the large impact on quality of life these complications have, reported rates of neurological complications vary immensely, ranging from 0.46% to 24%. MATERIALS AND METHODS:Data were obtained for patients undergoing initial posterior lumbar interbody fusion, transforaminal lumbar interbody fusion, anterior lumbar interbody fusion, posterolateral fusion, discectomy, and laminectomy procedures from January 2007 to June 2015 covered by the nationwide insurance carrier Humana. Patient records were analyzed to determine rates of dural tear, damage to nervous tissue, cauda equina syndrome, neurogenic bowel/bladder, and FBSS following each procedure. Rates were determined for patients undergoing single/multilevel procedures, by age, and for patients with a previous diagnosis of depression to determine the influence these factors had on the risk of neurologic complications. RESULTS:Analysis of 70,581 patient records revealed a dural tear rate of 2.87%, damage to the nervous tissue of 1.47%, cauda equina syndrome of 0.75%, neurogenic bowel or bladder of 0.45%, and FBSS of 15.05% following lumbar spine surgery. The incidence of complications was highest for patients undergoing multilevel procedures and posterior fusion. Depression was a significant risk factor for FBSS (risk ratio, 1.74; P<0.0001), damage to nervous tissue (1.41; P<0.0001), and dural tear (1.15; P<0.0001), but had no impact on risk of cauda equina syndrome or neurogenic bowel or bladder. Increased age was associated with higher rates of dural tear and damage to nervous tissue. CONCLUSIONS:Patients with a history of depression are at significantly increased risk for neurologic complications following lumbar spine surgery and should be managed accordingly.

STUDY DESIGN:Retrospective study of consecutive 113 cervical kinetic magnetic resonance images (kMRIs) and 57 radiographs. OBJECTIVE:To elucidate the relationship between C2-6 or C2-7 Cobb angle and cervical sagittal alignment parameters using kMRI, and evaluate the visibility of C6 and C7 inferior endplates on cervical radiographs. SUMMARY OF BACKGROUND DATA:Several studies have used C2-6 Cobb angle instead of C2-7 Cobb angle as C7 inferior endplate is not always visible because of overlying shadows. However, the relationship between C2-6 or C2-7 Cobb angle and cervical sagittal alignment parameters remains unclear. Moreover, visibility of C6 inferior endplate remains unknown. METHODS:C2-6 Cobb angle, C2-7 Cobb angle, occiput-C2 angle, Atlas-dens interval (ADI), narrowest oropharyngeal airway space (nPAS), cervical sagittal vertical axis (cSVA), cervical tilt, cranial tilt, neck tilt, thoracic inlet angle (TIA), and T1 slope were measured using kMRI, and analyzed for their relationship with C2-6 or C2-7 Cobb angle. Visibility rates of C6 or C7 inferior endplates were evaluated using cervical radiographs. RESULTS:Linear regression analysis showed high association between C2-6 and C2-7 Cobb angle (R = 0.696, P < 0.01). C2-6 Cobb angle was significantly correlated with occiput-C2 angle, TIA, T1 slope, neck tilt, cSVA, and cervical tilt; but not with nPAS, ADI, and cranial tilt. C2-7 Cobb angle resembled C2-6 Cobb angle regarding the relationships with other parameters. In our study, 94.7% C6 and 50.9% C7 inferior endplate were clearly visible; 1.8% C6 and 24.6% C7 inferior endplate were invisible. Chi-square test and residual analysis showed significant difference between the two groups (P < 0.01). CONCLUSION:C2-6 Cobb angle highly resembled C2-7 Cobb angle regarding its relationships with parameters of craniovertebral, cervical and thoracic inlet alignment. C2-6 Cobb angle could be an alternative to C2-7 Cobb angle because of its significantly higher visibility rate. LEVEL OF EVIDENCE:3.

STUDY DESIGN/METHODS:Retrospective cohort study. OBJECTIVE:To demonstrate the relationship between perioperative use of catheters and the incidence of surgical site infection (SSI) after cervical spine surgery, after adjusting for patient's age, severity of comorbidity, surgical approach, and use of instrumentation. SUMMARY OF BACKGROUND DATA/BACKGROUND:Although the association between SSI and the use of arterial catheters (ACs) or central venous catheters (CVCs) is established in cardiac surgery, the relation in the cervical spine was not well elucidated. METHODS:A private insurance database was analyzed. The incidence of SSI within 1 month postoperatively and the crude odds ratio (cOR) and 95% confidence interval (95% CI) were calculated based on the use of catheters. Subsequently, logistic regression analysis was performed to identify independent factors for SSI. Independent variables of the regression analysis included Charlson comorbidity index with the score of age, the use of CVC, the use of AC, surgical approach (anterior or posterior), and instrumentation (fusion or decompression alone). RESULTS:A total of 39,893 patients received cervical surgery between 2007 and 2015. Of these, 1.6% patients experienced an SSI. The incidence of SSI in patients treated with and without AC was 3.2% and 1.3%, respectively (cOR 2.44, 95% CI: 2.05-2.99, P < 0.001). Likewise, incidence of SSI in patients with and without CVC was 5.8% and 1.5%, respectively (cOR 2.61, 95% CI: 2.97-5.55, P < 0.001). Multivariate logistic regression analysis demonstrated that the adjusted OR was 1.66 in CVC use (95% CI: 1.08-2.46, P = 0.016), whereas the AC use was not significant variable (P = 0.086). CONCLUSION/CONCLUSIONS:The use of CVC can be a potential risk factor for SSI regardless of age, severity of comorbidity, surgical approach, or presence of instrumentation. Although the essential benefits of catheters are undisputed, our data can bring up the surgeon's attention to appropriate management of the CVC. LEVEL OF EVIDENCE/METHODS:3.

INTRODUCTION/BACKGROUND:With healthcare expenditure in the national forefront, outpatient arthroplasty is an appealing option in select patient populations. The purpose of this study was to determine the complication rates associated with outpatient total hip arthroplasty (THA) in comparison to standard inpatient THA. METHODS:We performed a retrospective review of the Humana subset of the PearlDiver insurance records database to identify patients undergoing THA (Current Procedural Terminology-27130 and Current Procedural Terminology-27132) as either outpatients or inpatients from 2007 to 2016. Multivariate logistic regression adjusting for age, gender, and Charlson Comorbidity Index were used to calculate odds ratios of complications among outpatients undergoing THA relative to inpatients undergoing THA. RESULTS:The query identified 2,184 patients who underwent outpatient THA and 73,596 patients who underwent inpatient THA. The median age was in the 65 to 69 age group and in the 70 to 74 age group for the outpatient and inpatient cohorts, respectively (P < 0.001). Outpatients undergoing THA had a significantly lower incidence of comorbid hypertension (P < 0.001), cerebrovascular disease (P = 0.001), obesity (P = 0.017), chronic obstructive pulmonary disorder (P = 0.045), and chronic kidney disease (P = 0.049). The incidence of both outpatient THA (P = 0.001) and inpatient THA (P < 0.001) increased over the study period. After adjusting for age, gender, and Charlson Comorbidity Index, patients undergoing outpatient THA had comparable rates of all queried surgical complications, including component revision, irrigation and debridement, and hip dislocation at 1 year. Rates of postoperative medical complications were also comparable between the two cohorts. CONCLUSION/CONCLUSIONS:Outpatient THA is increasing in frequency nationwide and has comparable postoperative complication rates. With its potential to minimize arthroplasty care costs, outpatient THA is a safe and effective option among appropriately selected patients.

PURPOSE/OBJECTIVE:To evaluate the kinematic change of cross-sectional area of lumbar intervertebral foramen in degenerative lumbar spondylolisthesis patients using multi-positional MRI. METHODS:Multi-positional MRI was performed on 31 patients diagnosed with single or multilevel degenerative lumbar spondylolisthesis and 31 control patients without degenerative lumbar spondylolisthesis. Foraminal area (FA) was measured at the lumbar spondylolisthesis level in degenerative lumbar spondylolisthesis group and at L3-4, L4-5, and L5-S1 level in the control group. FA was measured bilaterally in neutral, flexion, and extension positions. The difference in FA between the groups was analyzed using Mann-Whitney U test, and the difference between positions within groups was analyzed using Wilcoxon signed-rank test. RESULTS:Degenerative lumbar spondylolisthesis group showed significantly smaller FA on both sides and on average in all three positions compared to the control group (p < 0.05 all). From neutral to flexion position, the change in FA was significantly smaller in the degenerative lumbar spondylolisthesis group than in the control group on both sides and on average (p < 0.005 all). In degenerative lumbar spondylolisthesis group, the FA showed no significant change from neutral to flexion, but showed significant change from neutral to extension (p < 0.005 all). CONCLUSIONS:FA in the degenerative lumbar spondylolisthesis group was smaller than in the control group. There was no difference in FA in degenerative lumbar spondylolisthesis group from neutral to flexion, only from neutral to extension. Patients with degenerative lumbar spondylolisthesis have a higher chance of developing foraminal stenosis.

STUDY DESIGN/METHODS:Retrospective review. PURPOSE/OBJECTIVE:To identify the trends in stimulator use, pair those trends with various grafting materials, and determine the influence of stimulators on the risk of revision surgery. OVERVIEW OF LITERATURE/BACKGROUND:A large number of studies has reported beneficial effects of electromagnetic energy in healing long bone fractures. However, there are few clinical studies regarding the use of electrical stimulators in spinal fusion. METHODS:We used insurance billing codes to identify patients with lumbar disc degeneration who underwent anterior lumbar interbody fusion (ALIF). Comparisons between patients who did and did not receive electrical stimulators following surgery were performed using logistic regression analysis, chi-square test, and odds ratio (OR) analysis. RESULTS:Approximately 19% of the patients (495/2,613) received external stimulators following ALIF surgery. There was a slight increase in stimulator use from 2008 to 2014 (multi-level R2=0.08, single-level R2=0.05). Patients who underwent multi-level procedures were more likely to receive stimulators than patients who underwent single-level procedures (p<0.05; OR, 3.72; 95% confidence interval, 3.02-4.57). Grafting options associated with most frequent stimulator use were bone marrow aspirates (BMA) plus autograft or allograft for single-level and allograft alone for multi-level procedures. In both cohorts, patients treated with bone morphogenetic proteins were least likely to receive electrical stimulators (p<0.05). Patients who received stimulation generally had higher reimbursements. Concurrent posterior lumbar fusion (PLF) (ALIF+PLF) increased the likelihood of receiving stimulators (p<0.05). Patients who received electrical stimulators had similar revision rates as those who did not receive stimulation (p>0.05), except those in the multilevel ALIF+PLF cohort, wherein the patients who underwent stimulation had higher rates of revision surgery. CONCLUSIONS:Concurrent PLF or multi-level procedures increased patients' likelihood of receiving stimulators, however, the presence of comorbidities did not. Patients who received BMA plus autograft or allograft were more likely to receive stimulation. Patients with and without bone stimulators had similar rates of revision surgery.

BACKGROUND:The purpose of this study is to assess the incidence, risk factors for, and types of respiratory complications occurring in patients undergoing lumbar spine surgery. METHODS:codes and Current Procedural Terminology codes to determine the incidence of pneumonia, pleural effusion, pulmonary collapse, and acute respiratory failure for each procedure type. The incidence of these complications in patients with the risk factors diabetes mellitus, chronic obstructive pulmonary disease (COPD), and smoking was also examined. RESULTS:< .01). CONCLUSION/CONCLUSIONS:The results of this study show that patients who have a history of smoking, COPD, or diabetes mellitus are at a greater risk for respiratory complications following lumbar spine surgery. These findings are useful for patient selection, clinical decision-making, and preoperative counseling.