Faculty Bibliography

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.

STUDY DESIGN/METHODS:A retrospective case-control study. OBJECTIVE:The aim of this study was to determine the nationwide trends and complication rates associated with outpatient posterior lumbar fusion (PLF). SUMMARY OF BACKGROUND DATA/BACKGROUND:Outpatient lumbar spine fusion is now possible secondary to minimally invasive techniques that allow for reduced hospital stays and analgesic requirements. Limited data are currently available regarding the clinical outcome of outpatient lumbar fusion. METHODS:The Humana administrative claims database was queried for patients who underwent one to two-level PLF (CPT-22612 or CPT-22633 AND ICD-9-816.2) as either outpatients or inpatients from Q1 2007 to Q2 2015. The incidence of perioperative medical and surgical complications was determined by querying for relevant International Classification of Diseases and Current Procedural Terminology codes. Multivariate logistic regression adjusting for age, gender, and Charlson Comorbidity Index was used to calculate odds ratios (ORs) of complications among outpatients relative to inpatients undergoing PLF. RESULTS:Cohorts of 770 patients who underwent outpatient PLF and 26,826 patients who underwent inpatient PLF were identified. The median age was in the 65 to 69 years age group for both cohorts. The annual relative incidence of outpatient PLF remained stable across the study period (R = 0.03, P = 0.646). Adjusting for age, gender, and comorbidities, patients undergoing outpatient PLF had higher likelihood of revision/extension of posterior fusion [(OR 2.33, confidence interval (CI) 2.06-2.63, P < 0.001], anterior fusion (OR 1.64, CI 1.31-2.04, P < 0.001), and decompressive laminectomy (OR 2.01, CI 1.74-2.33, P < 0.001) within 1 year. Risk-adjusted rates of all other postoperative surgical and medical complications were statistically comparable. CONCLUSION/CONCLUSIONS:Outpatient lumbar fusion is uncommonly performed in the United States. Data collected from a national private insurance database demonstrate a greater risk of postoperative surgical complications including revision anterior and posterior fusion and decompressive laminectomy. Surgeons should be cautious in performing PLF in the outpatient setting, as the risk of revision surgery may increase in these cases. LEVEL OF EVIDENCE/METHODS:3.

BACKGROUND CONTEXT:Cervical sagittal vertical axis (cSVA) of ≥40 mm is recognized as the key factor of poor health-related quality of life, poor surgical outcomes, and correction loss after surgery for cervical deformity. However, little is known about the radiological characteristics of patients with cSVA≥40 mm. PURPOSE:The purpose of this study was to identify the radiological characteristics of patients with cervical imbalance. DESIGN:Retrospective analysis of weight-bearing cervical magnetic resonance (MR) images. PATIENT SAMPLE:Consecutive 1,500 MR images of symptomatic patients in weight-bearing position. OUTCOME MEASURES:Cervical sagittal vertical axis, cervical alignment, cervical balance parameters (T1 slope, Co-C2 angle, C2-C7 angle, C7-T1 angle, neck tilt, and thoracic inlet angle), disc degeneration (Pfirmann and Suzuki classification), end plate degeneration (Modic change), spondylolisthesis (antero- and retrolisthesis), anteroposterior (AP) diameter of dural sac, cross-sectional area (CSA), and fat infiltration ratio of the transversospinalis muscles at C4 and C7 levels. METHODS:Patients were divided into two groups: cSVA≥40 mm and cSVA<40 mm. Gender, age, and cervical alignment were analyzed. Subsequently, matched imbalance (cSVA≥40 mm) and control (<40 mm) groups were created using the propensity score to adjust for age, gender, and cervical alignment. Cervicothoracic angular parameters, disc degeneration, Modic change, spondylolisthesis, and degeneration of the transversospinalis muscles at C4 and C7 were compared. Variables with p<.05 were included in the multinomial logistic regression model to identify factors that relate to the cervical balance grouping. RESULTS:The incidence of patients with cervical imbalance was 2.5% (37 patients). Those patients had a higher incidence of kyphosis, were older, and there were more male patients. In the matched imbalance group, the T1 slope was greater (p=.028), C7-T1 lordotic angle was smaller (p<.001), the number of anterolisthesis was greater (p=.012), and the fat infiltration ratio at C4 and C7 was higher (p=.023, 0.030) compared with the control. Logistic regression analysis showed that the C7-T1 angle (adjusted odds ratio [aOR]=0.592, p=.001) and fat infiltration ratio at C7 level (aOR=1.178, p=.030) were significant independent variables. CONCLUSIONS:Smaller C7-T1 lordotic angle and severe muscle degeneration at C7 level were independent characteristics of patients with cervical imbalance.

The purpose of this study was to determine the relative incidence of postoperative complications in 25-hydroxyvitamin D (25D)-deficient and -sufficient patients undergoing total knee arthroplasty (TKA). Patients who were either serum 25D deficient (25D <20 ng/mL) or 25D sufficient (25D ≥20 ng/mL) 90 days prior to primary TKA from 2007 to 2016 were identified using the Humana administrative claims registry. The incidence of postoperative medical and surgical complications was determined by querying for relevant International Classification of Diseases, Ninth Revision and Current Procedural Terminology codes. Risk-adjusted odds ratios (ORs) were calculated using multivariate logistic regression with age, sex, and Charlson Comorbidity Index as covariates. In total, 868 of 6593 patients who underwent TKA from 2007 to 2016 were 25D deficient, corresponding to a 13.2% prevalence rate. On adjustment for age, sex, and Charlson Comorbidity Index, 25D-deficient patients had a higher incidence of postoperative stiffness requiring manipulation under anesthesia (OR, 1.69; 95% confidence interval [CI], 1.39-2.04; P<.001), surgical site infection requiring irrigation and debridement (OR, 1.76; 95% CI, 1.25-2.48; P=.001), and prosthesis explantation (OR, 2.97; 95% CI, 2.04-4.31; P<.001) at 1 year. Patients who were 25D deficient also had higher rates of postoperative deep venous thrombosis (OR, 1.80; 95% CI, 1.36-2.38; P<.001), myocardial infarction (OR, 2.11; 95% CI, 1.41-3.15; P<.001), and cerebrovascular accident (OR, 1.73; 95% CI, 1.17-2.57; P=.006). Thus, serum 25D levels below 20 ng/mL are associated with a higher incidence of postoperative complications and may be a perioperative modifiable risk factor in TKA. [Orthopedics. 2018; 41(4):e489-e495.].

BACKGROUND CONTEXT:The thoracic spine was previously known as a relatively stable region in human spine. Several studies reported that the motion of the thoracic spine and changes in the cross-sectional area of the spinal cord changed with positions in the sagittal plane. The kinematic relationship between the thoracic disc and the space available for cord (SAC) with the positional change is still not well investigated. PURPOSE:The objective of this study was to evaluate the kinematic change of the intervertebral disc and space available for the spinal cord of the thoracic spine using kinematic magnetic resonance imaging (kMRI). STUDY DESIGN:This is a retrospective study. PATIENT SAMPLE:The patient sample included 105 patients who underwent thoracic spine kMRI. OUTCOME MEASUREMENT:Disc bulging and the SAC were evaluated from T4-T5 to T11-T12 in flexion, neutral, and extension positions. METHODS:MRAnalyzer3 (TrueMRI Corporation, Bellflower, CA, USA) was used to analyze disc bulging and SAC from T4-T5 to T11-T12. The Friedman test was used to analyze the differences in disc bulging and SAC between neutral, flexion, and extension positions at each segment. The Wilcoxon signed-rank test was used for post hoc analysis for the significant levels from the Friedman test. RESULTS:The mean value of the thoracic intervertebral disc area from T4-T5 to T11-T12 tended to be larger in flexion than in extension. Initial analysis with the Friedman test revealed a significant difference in disc bulging at T8-T9, T9-T10, and T11-T12 among the three positions (p<.05). Post hoc analysis showed that disc bulging was only significant at T8-T9 between flexion and extension (p<.001), at T9-T10 between neutral and flexion (0.003), and at T9-T10 between flexion and extension (p=.004). The SAC from T4-T5 to T11-T12 tended to be widest in extension and narrowest in flexion. Only T5-T6 exhibited a statistically significant difference in SAC between flexion and extension (p=.002). CONCLUSIONS:The thoracic discs and the SAC from T4-T5 to T11-T12 showed kinematic changes from flexion to extension. The thoracic spinal canal tended to be narrowest in flexion and widest in the extension. Thus, kyphotic deformities could be one of the etiologies for neurogenic deterioration in patients with thoracic myelopathy.

BACKGROUND CONTEXT:With the changing landscape of health care, outpatient spine surgery is being more commonly performed to reduce cost and to improve efficiency. Anterior cervical discectomy and fusion (ACDF) is one of the most common spine surgeries performed and demand is expected to increase with an aging population. PURPOSE:The objective of this study was to determine the nationwide trends and relative complication rates associated with outpatient ACDF. STUDY DESIGN/SETTING:This is a large-scale retrospective case control study. PATIENT SAMPLE:The patient sample included Humana-insured patients who underwent one- to two-level ACDF as either outpatients or inpatients from 2011 to 2016 OUTCOME MEASURES: The outcome measures included incidence and the adjusted odds ratio (OR) of postoperative medical and surgical complications within 1 year of the index surgery. MATERIALS AND METHODS:A retrospective review was performed of the PearlDiver Humana insurance records database to identify patients undergoing one- to two-level ACDF (Current Procedural Terminology [CPT]-22551 and International Classification of Diseases [ICD]-9-816.2) as either outpatients or inpatients from 2011 to 2016. The incidence of perioperative medical and surgical complications was determined by querying for relevant ICD and CPT codes. Multivariate logistic regression adjusting for age, gender, and Charlson Comorbidity Index was used to calculate ORs of complications among outpatients relative to inpatients undergoing ACDF. RESULTS:=0.82, p=.04). Adjusting for age, gender, and comorbidities, patients undergoing outpatient ACDF were more likely to undergo revision surgery for posterior fusion at both 6 months (OR 1.58, confidence interval [CI] 1.27-1.96, p<.001) and 1 year (OR 1.79, CI 1.51-2.13, p<.001) postoperatively. Outpatient ACDF was also associated with a higher likelihood of revision anterior fusion at 1 year postoperatively (OR 1.46, CI 1.26-1.70, p<.001). Among medical complications, postoperative acute renal failure was more frequently associated with outpatient ACDF than inpatient ACDF (OR 1.25, CI 1.06-1.49, p=.010). Adjusted rates of all other queried surgical and medical complications were comparable. CONCLUSIONS:Outpatient ACDF is increasing in frequency nationwide over the past several years. Nationwide data demonstrate a greater risk of perioperative surgical complications, including revision anterior and posterior fusion, as well as a higher risk of postoperative acute renal failure. Candidates for outpatient ACDF should be counseled and carefully selected to reduce these risks.

STUDY DESIGN/METHODS:Systematic review. OBJECTIVES/OBJECTIVE:The aim was to determine the fusion efficacy of allograft and demineralized bone matrix (DBM) in lumbar instrumented and noninstrumented fusion procedures for degenerative lumbar disorders. METHODS:A literature search was conducted using the PubMed and Cochrane databases. To be considered, publications had to meet 4 criteria: patients were treated for a degenerative lumbar disorder, a minimum group size of 10 patients, use of allograft or DBM, and at least a 2-year follow-up. Data on the study population, follow-up time, surgery type, grafting material, fusion rates, and its definition were collected. RESULTS:The search yielded 692 citations with 17 studies meeting the criteria including 4 retrospective and 13 prospective studies. Six studies used DBM and 11 employed allograft alone or in the combination with autograft. For the allograft, fusion rates ranged from 58% to 68% for noninstrumented and from 68% to 98% for instrumented procedures. For DBM, fusion rates were 83% for noninstrumented and between 60% and 100% for instrumented lumbar fusion procedures. CONCLUSIONS:Both allograft and DBM appeared to provide similar fusion rates in instrumented fusions. On the other hand, in noninstrumented procedures DBM was superior. However, a large variation in the type of surgery, outcomes collection, lack of control groups, and follow-up time prevented any significant conclusions. Thus, studies comparing the performance of allograft and DBM to adequate controls in large, well-defined patient populations and with a sufficient follow-up time are needed to establish the efficacy of these materials as adjuncts to fusion.