Faculty Bibliography

STUDY DESIGN/UNASSIGNED:Retrospective upright MRI study. OBJECTIVE/UNASSIGNED:To validate the presence of positive and negative nerve root sedimentation signs on multi-positional MRI in the upright position and explore the relationship between negative nerve root sedimentation and gravity. METHODS/UNASSIGNED:T2-weighted axial multi-positional images in the upright position at the intervertebral disc levels from L1-L2 to L4-L5 in 141 patients with non-specific low back pain were retrospectively assessed. A positive sedimentation sign was defined as the absence of nerve root sedimentation or the absence of dorsal conglomeration of nerve roots within the dural sac. A negative sedimentation sign was defined as nerve root sedimentation dorsally or dorso-laterally like a horseshoe. Intra-and inter-observer reliability was evaluated. The relationship between sedimentation sign and dural sac cross-sectional area (CSA), anterior-posterior (AP) diameter was also explored. RESULTS/UNASSIGNED:The kappa value of intra-observer reliability was 0.962 and inter-observer reliability was 0.925. Both positive and negative sedimentation signs did appear at all 4 lumbar levels, including L1/2, L2/3, L3/4 and L4/5. A positive sedimentation sign was associated with significantly decreased dural sac CSA and AP diameter at L2/3, L3/4 or L4/5 level when compared to negative sedimentation sign. CONCLUSIONS/UNASSIGNED:Both negative and positive sedimentation signs appeared at the L1/2, L2/3, L3/4, and L4/5 levels on the upright MRI, which suggested that the presence of nerve roots sedimenting dorsally in patients may not be associated with gravity. Moreover, the current study supports that sedimentation signs on multi-positional MRI images could have the same diagnostic functions as on MRI images.

STUDY DESIGN/UNASSIGNED:Retrospective database. OBJECTIVES/UNASSIGNED:Although posterior decompression is the most common approach for surgical treatment of degenerative thoracic spine disease, anterior approach is gaining interest due to its advantage in disc visualization. The objective of this study was to compare the intra- and postoperative medical complication rates between anterior and posterior decompression for degenerative thoracic spine pathologies. METHODS/UNASSIGNED:A national US insurance database was queried for patients with degenerative diagnoses who had undergone anterior or posterior thoracic decompression. Incidence of intra- and postoperative complications were evaluated on the day of surgery and within 1 and 3 months. Two subgroups were matched based on age, gender, and comorbidity. The association of decompression approach and complications was assessed using logistic regression. RESULTS/UNASSIGNED:A total of 1459 patients were included, consisting of 1004 patients in posterior and 455 patients in anterior group. Respiratory complications were the most common complications on the day of surgery (8.57%) and within 30 days (17.75%). Matched analysis showed that anterior approach was associated with organ failure, gastrointestinal, and device-/implant-/graft-related complications in all follow-up periods; and with cardiovascular, deep venous thrombosis/pulmonary embolism, and respiratory complications in at least 1 follow-up period. Among respiratory complications, anterior decompression was significantly associated with noninfectious etiologies on the day of surgery (odds ratio [OR] = 1.72), within 30 days (OR = 2.05), and within 90 days (OR = 1.92). CONCLUSIONS/UNASSIGNED:Anterior approach was associated with increased rates of several complications. High rates of respiratory complications necessitate comprehensive preoperative risk stratification to identify those who may benefit more from posterior approach.

PURPOSE:To elucidate the effects of bisphosphonates on complications following posterior lumbar fusion (PLF) with a large database study. METHODS:The PearlDiver Patient Record Database was queried to identify adult patients who had undergone posterior lumbar fusion (PLF). Those patient cohorts were divided based on a diagnosis of osteoporosis prior to surgery and bisphosphonate usage. This yielded three groups: Osteo+Bisph+, Osteo+Bisph-, and Osteo-Bisph-. The primary outcome of the present study was revision rates at 6 months and 1 year following surgery. Incidence of postoperative complications was analyzed, and statistical analysis was conducted using Pearson chi-square analysis. RESULTS:Patients taking bisphosphonates did not have significantly different rates of revision surgery at 6 months and 1 year, instrumentation complications, or post-vertebral fractures than patients not taking bisphosphonates. Additionally, osteoporotic patients did not have significantly different rates of these complications than patients without osteoporosis. CONCLUSION:Bisphosphonate usage did not significantly affect the rates of postoperative complications following posterior lumbar fusion. Further research is required to fully elucidate the effects of bisphosphonates on outcomes and complications following spine surgery.

STUDY DESIGN/UNASSIGNED:Review. OBJECTIVE/UNASSIGNED:A comparative overview of cost-effectiveness between minimally invasive versus and equivalent open spinal surgeries. METHODS/UNASSIGNED:A literature search using PubMed was performed to identify articles of interest. To maximize the capture of studies in our initial search, we combined variants of the terms "cost," "minimally invasive," "spine," "spinal fusion," "decompression" as either keywords or MeSH terms. PearlDiver database was queried for open and minimally invasive surgery (MIS; endoscopic or percutaneous) reimbursements between Q3 2015 and Q2 2018. RESULTS/UNASSIGNED:In general, MIS techniques appeared to decrease blood loss, shorten hospital lengths of stay, mitigate complications, decrease perioperative pain, and enable quicker return to daily activities when compared to equivalent open surgical techniques. With regard to cost, primarily as a result of these latter benefits, MIS was associated with lower costs of care when compared to equivalent open techniques. However, cost reporting was sparse, and relevant methodology was inconsistent throughout the spine literature. Within the PearlDiver data sets, MIS approaches had lower reimbursements than open approaches for both lumbar posterior fusion and discectomy. CONCLUSIONS/UNASSIGNED:Current data suggests that overall cost-savings may be incurred with use of MIS techniques. However, data reporting on costs lacks in uniformity, making it difficult to formulate any firm conclusions regarding any incremental improvements in cost-effectiveness that may be incurred when utilizing MIS techniques when compared to equivalent open techniques.

STUDY DESIGN/UNASSIGNED:Retrospective comparative study. OBJECTIVES/UNASSIGNED:To compare the perioperative complications of propensity score-matched cohorts of patients with degenerative cervical myelopathy (DCM), who were treated with anterior cervical discectomy and fusion (ACDF), posterior laminectomy with fusion, or laminoplasty. METHODS/UNASSIGNED:The Humana PearlDiver Patient Record Database was queried using the International Classification of Diseases (ICD-9 and ICD-10) and the Current Procedural Terminology (CPT) codes. Propensity score-matched analysis was done using multiple Chi-squared tests with Bonferroni correction of the significance level. RESULTS/UNASSIGNED:< 0.001. CONCLUSIONS/UNASSIGNED:The incidence of dysphagia following laminectomy with fusion was not different compared to ACDF. Postoperative new-onset cervicalgia and revisions were least common in laminoplasty. The highest rate of postoperative limb paralysis was noticed in laminectomy with fusion.

OBJECTIVE:The objective of this study was to evaluate the characteristics and performance of current prediction models in the fields of spine metastasis and degenerative spine disease to create a scoring system that allows direct comparison of the prediction models. METHODS:A systematic search of PubMed and Embase was performed to identify relevant studies that included either the proposal of a prediction model or an external validation of a previously proposed prediction model with 1-year outcomes. Characteristics of the original study and discriminative performance of external validations were then assigned points based on thresholds from the overall cohort. RESULTS:Nine prediction models were included in the spine metastasis category, while 6 prediction models were included in the degenerative spine category. After assigning the proposed utility of prediction model score to the spine metastasis prediction models, only 1 reached the grade of excellent, while 2 were graded as good, 3 as fair, and 3 as poor. Of the 6 included degenerative spine models, 1 reached the excellent grade, while 3 studies were graded as good, 1 as fair, and 1 as poor. CONCLUSIONS:As interest in utilizing predictive analytics in spine surgery increases, there is a concomitant increase in the number of published prediction models that differ in methodology and performance. Prior to applying these models to patient care, these models must be evaluated. To begin addressing this issue, the authors proposed a grading system that compares these models based on various metrics related to their original design as well as internal and external validation. Ultimately, this may hopefully aid clinicians in determining the relative validity and usability of a given model.

LEVEL OF EVIDENCE/METHODS:3.

STUDY DESIGN/UNASSIGNED:Retrospective cross-sectional study. OBJECTIVES/UNASSIGNED:To determine if pre-operative albumin and CRP can predict post-operative infections after lumbar surgery. METHODS/UNASSIGNED:Patients who underwent an anterior lumbar interbody fusion (ALIF), posterior lumbar interbody fusion (PLIF), or lumbar discectomy were identified using a patient record database (PearlDiver) and were included in this retrospective study. Patients were stratified by Charlson Comorbidity Index (CCI) scores and pre-operative albumin and CRP status. Post-operative complications included deep infections and urinary tract infections within 3 months of the surgery and revisions within 1 year of the surgery. RESULTS/UNASSIGNED:74,280 patients were included in this study. 21,903 had pre-operative albumin or CRP lab values. 7,191 (33%), 12,183 (56%), and 2,529 (12%) patients underwent an ALIF, PLIF, and a lumbar discectomy, respectively. 16,191 did not have any complication (74%). The most common complication was UTI (16%). Among all patients, hypoalbuminemia was a significant risk factor for deep infection and UTI after ALIF, deep infection, UTI, and surgical revision after PLIF, and deep infection after lumbar discectomy. Elevated CRP was a significant risk factor for deep infection after ALIF, UTI after PLIF, and deep infection after lumbar discectomy in patients with a CCI ≤ 3. CONCLUSIONS/UNASSIGNED:Pre-operative hypoalbuminemia and elevated CRP were significant risk factors for deep infection, UTI, and/or revision, after ALIF, PLIT, and/or lumbar discectomy. Future studies with a larger population of patients with low albumin and high CRP values are needed to further elaborate on the current findings.

STUDY DESIGN:Retrospective radiographic study. OBJECTIVE:The aim of this study was to compare disks with and without high-intensity zones (HIZ) to understand the impact of an HIZ on the stability of corresponding lumbar spinal segments. SUMMARY OF BACKGROUND DATA:Previous studies have established a relationship between back pain and the presence of HIZ on T2-weighted images of magnetic resonance imaging. These previous studies, however, used either plain radiographs or static (neutral position) magnetic resonance imaging to assess their chosen variables. MATERIALS AND METHODS:We retrospectively reviewed 140 consecutive patients with MR images taken in weight-bearing neutral, flexion, and extension positions. We separated segments into those with HIZ and without HIZ and assessed the grade of disk degeneration for each segment. Subsequently, a matched control group was selected from the segments without HIZ. Multiple factors were compared in a univariate analysis. A multinomial logistic regression analysis was conducted to assess the association between angular range of motion (ROM) >10 degrees and translational motion >2 mm with multiple independent variables. RESULTS:Upon assessment of the 700 lumbar segments, 70 (10%) segments had an HIZ and 68 patients had a single HIZ. On univariate analysis, the presence of an HIZ was not found to be significantly associated with degree of fatty muscle degeneration (P=0.969), muscle volume (P=0.646), degree of facet joint osteoarthritis (P=0.706), intervertebral disk height (P=0.077), Modic change (P=0.951), lower endplate shape (P=0.702), upper endplate shape (P=0.655), or degree of disk degeneration (P=0.607). Multifactorial analysis showed that none of the independent variables significantly correlated with angular ROM >10 degrees. For translational motion, the only significant correlation was the Goutallier classification (P=0.017). CONCLUSIONS:The presence of HIZ did not significantly affect spinal stability as measured by angular ROM and translational motion and was not associated with significant changes in several quantitative measurements of spine pathology.

PURPOSE:To evaluate the effect of cervical sagittal alignment on craniocervical junction kinematic. METHODS:We retrospectively reviewed 359 patients (119 cervical lordosis, 38 cervical sagittal imbalances, 111 cervical straight, and 91 cervical kyphosis) who underwent cervical spine multi-positional magnetic resonance imaging (mMRI). The C2-7 angle, disc degeneration grading and cSVA were analyzed in neutral position. The C3-5 OCI, O-C2 angle, and OCD were analyzed in neutral, flexion, and extension position. The Kruskal-Wallis test was used to detect difference among four groups. The post hoc analysis was performed by Mann-Whitney U test. RESULTS:The cervical sagittal imbalance, cervical straight, and cervical kyphosis groups had significantly more lordosis angle in C3 and C4 OCI and O-C2 angle than the cervical lordosis group (p < 0.0125). Head motion in relation to C2, C3, and C4 (O-C2 angle, C3-4 OCI) in the kyphosis group was significantly greater than in the cervical lordosis group (p < 0.0125). The cervical sagittal imbalance group showed significantly increased O-C2 angle than the cervical lordosis group (p = 0.008). Regression analysis showed that an increase in O-C2 angle by one unit had a relative risk of 4.3% and 3.5% for a patient to be in the cervical sagittal imbalance and cervical kyphosis groups, respectively. CONCLUSIONS:Cervical sagittal alignment affected craniocervical junction motion with the head exhibiting greater extension and motion in the cervical sagittal imbalance and cervical kyphosis groups. Motion of the head in relation to C2 can be used to predict the cervical sagittal alignment.