Faculty Bibliography

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.

BACKGROUND:Intraoperative neuromonitoring (ION), such as motor-evoked potential (MEP), somatosensory evoked potentials (SSEP), and electromyography (EMG), is used to detect impending neurological injuries during spinal surgery. To date, little is known about the trends in the use of ION for scoliosis surgery in the United States. METHODS:A retrospective review was performed using the PearlDiver Database to identify patients that had scoliosis surgery with and without ION from years 2005 to 2011. Demographic information (such as age, gender, region within the United States) and clinical information (such as type of ION and rates of neurological injury) were assessed. RESULTS:< .0001). CONCLUSIONS:The use of ION for scoliosis surgery gradually increased annually from 2005 to 2011. Age and regional differences were noted with neuromonitoring being most commonly used for scoliosis surgery in nonelderly patients and in the Northeastern part of the United States. No differences were noted in the risk of neurological injury in patients that had surgery with and without ION. Although the findings from this study may seem to suggest that ION may not influence the risk of neurologic injury, this result must be interpreted with caution as inherently riskier surgeries may utilize ION more, leading to an actual reduction in injuries more dramatic than observed in this study.

Outpatient arthroplasty is an appealing option among select patient populations as a mechanism for reducing health care expenditure. The purpose of this study was to determine the nationwide trends and complication profile of outpatient total shoulder arthroplasty (TSA). The authors reviewed a national administrative claims database to identify patients undergoing TSA as outpatients and inpatients from 2007 to 2016. The incidence of perioperative surgical and medical complications was determined by querying for relevant International Classification of Diseases, Ninth Revision, and Current Procedural Terminology codes. Multivariate logistic regression adjusted for age, sex, and Charlson Comorbidity Index was used to calculate odds ratios of complications among outpatients relative to inpatients undergoing TSA. The query identified 1555 patients who underwent outpatient TSA and 15,987 patients who underwent inpatient TSA. The median age was in the 70 to 74 years age group in both the outpatient and the inpatient cohorts, and the age distribution was comparable between the 2 cohorts (P=.287). The incidence of both outpatient (P<.001) and inpatient (P<.001) TSA increased during the study period. On adjustment for age, sex, and comorbidities, patients undergoing outpatient TSA had significantly lower rates of stiffness requiring manipulation under anesthesia (outpatient, 1.09%; inpatient, 2.35%; odds ratio, 0.52; 95% confidence interval, 0.38-0.71; P<.001) and higher rates of postoperative surgical site infections requiring reoperation (outpatient, 0.90%; inpatient, 0.65%; odds ratio, 1.65; 95% confidence interval, 1.15-2.35; P<.001) at 1 year. Rates of all other postoperative complications were comparable. Ambulatory TSA is increasing in incidence nationwide and is associated with an overall favorable postoperative complication profile. [Orthopedics. 2018; 41(3):e400-e409.].

STUDY DESIGN:Retrospective study. OBJECTIVE:To evaluate how each type of sagittal cervical alignment affects the motion of the upper and subaxial cervical spine using kinematic magnetic resonance imaging. SUMMARY OF BACKGROUND DATA:The sagittal malalignment of the cervical spine from degeneration in the subaxial cervical spine reflects a disruption in the kinematic properties of the cervical spine and affects the motion of adjacent segments. Changes in the sagittal parameters and kinematics of the upper cervical spine and upper thoracic spine due to the kyphosis are unknown. METHODS:Kinematic magnetic resonance imaging of the cervical spine in neutral position from 311 patients, including 90 lordotic, 90 straight, 90 global kyphotic, and 41 segmental kyphotic were analyzed. The lordotic angle at the upper and lower cervical spine, and T1 slope were measured in the neutral position and again in flexion and extension for dynamic analysis. RESULTS:The number of levels with significant disk degeneration was higher in the global kyphosis group. In the global kyphosis group, neutral sagittal parameters showed some characteristics of compensation to the malalignment. Compared with the lordotic group, patients with global kyphosis demonstrated significantly higher lordotic angle of the upper cervical spine and more horizontal T1 slope. The dynamic evaluation showed greater range of motion of the entire cervical spine and subaxial cervical spine in younger patients. However, we still found greater range of motion of the occipito-atlanto-axial complex in global kyphosis, even when controlling for age and number of levels with significant disk degeneration. CONCLUSION:Sagittal malalignment of the cervical spine affects all parts of the cervical motion complex. The global kyphotic alignment of subaxial cervical spine affects the kinematic properties of the occipito-atlanto-axial complex and upper thoracic spine to compensate for the alteration of cervical alignment. These differences are not seen in straight and segmental kyphosis. LEVEL OF EVIDENCE:Level 3.

PURPOSE:The cross-sectional area and fat infiltration are accepted as standard parameters for quantitative and qualitative evaluation of muscle degeneration. However, they are time-consuming, which prevents them from being used in a clinical setting. The aim of this study was to analyze the relationship between lumbar muscle degeneration and spinal degenerative disorders, using lumbar indentation value (LIV) as quantitative and Goutallier classification as qualitative measures. METHODS:This is a retrospective analysis of kinematic magnetic resonance images (kMRI). Two-hundred and thirty patients with kMRIs taken in weight-bearing positions were selected randomly. The LIV and Goutallier classification were evaluated at L4-5. The correlation of these two parameters with patients' age, gender, lumbar lordosis (LL), range of motion, disc degeneration, disc height, and Modic change were analyzed. RESULTS:There was no significant trend of LIV among the different grades of Goutallier classification (p = 0.943). There was a significant increase in age with higher grades of Goutallier classification (p < 0.001). In contrast, there was no correlation between LIV and age (p = 0.799). The Goutallier classification positively correlated with LL (r = 0.377) and severe disc degeneration (r = 0.249). The LIV positively correlated with LL (r = 0.476) and degenerative spondylolisthesis (r = 0.184). Multinomial logistic regression analysis showed that age (p = 0.026), gender (p = 0.003), and LIV (p < 0.001) were significant predictors for patients with low LL (< 10°). CONCLUSION:Lumbar muscle quantity and quality showed specific correlation with age and spine disorders. Additionally, LL can be predicted by the muscle quantity, but not the quality. These time-saving evaluation tools potentially accelerate the study of lumbar muscles. These slides can be retrieved under Electronic Supplementary Material.

PURPOSE:Although the T1 vertebra is considered as an important factor of cervical balance, little is known about its motion between flexion and extension. The purpose of present study was to analyze the T1 sagittal motion using kinematic magnetic resonance imaging (kMRI), and to identify factors that relate to T1 sagittal motion. METHODS:We retrospectively analyzed 145 kMR images taken in weight-bearing neutral, flexion and extension positions. Cervical balance parameters were evaluated in each position. The degree of T1 sagittal motion was defined as [(T1 slope at extension) - (T1 slope at flexion)]. All patients were divided into three groups: Positive group (T1 followed the head motion, T1 sagittal motion > 5°), Stable group (5 ≥, ≥ - 5) and Negative group (T1 moved in the opposite direction from the head motion, > - 5). The groups were compared and multivariate logistic regression analysis was calculated. RESULTS:There were 57 (40%) patients in the positive, 56 (39%) in the stable and 32 (22%) in the negative group. The positive group had the largest C2-7 sagittal vertical axis in flexion (p < 0.001) and the shortest in the extension (p = 0.023). Similar trends were seen in cranial tilt and cervical tilt. The value of T1 height < 27 mm was a significant independent factor for the negative group (p = 0.008, adjusted odds ratio = 5.958). CONCLUSION:Based on T1 sagittal motion, 40% of the patients were classified in positive group (the T1 vertebra followed the head motion in flexion and extension), and 20% were classified in the negative group (the T1 vertebra moved in the opposite direction from the head motion). T1 height < 27 mm was a potential predictor of negative group.

PURPOSE:To test the reliability and validity of the multi-positional magnetic resonance imaging (MRI) in measuring cervical angular parameter using the standard dynamic cervical X-ray as a reference. METHODS:All patients who underwent both cervical dynamic plain radiograph and multi-positional MRI on the same day between 2010 and 2016 were included in this study. The C2-7 angle and the segmental angles of the C2-3 to C6-7 segments were measured in all three positions (neutral, flexion, and extension) using multi-positional MRI and dynamic radiograph. The Pearson's correlation coefficients and linear regression analysis were used for statistical analysis. RESULTS: = 0.107-0.571). CONCLUSIONS:The C2-7 angle and segmental cervical angles measured by multi-positional MRI were valid, and reliability substituted the dynamic X-ray measurement within the acceptable range of error. Multi-positional MRI can be used as a reliable tool for angular parameter measurement and detection of angular instability in the cervical spine.

STUDY DESIGN:Retrospective analysis of consecutive 45 radiographs and 120 kinematic magnetic resonance images (kMRI) OBJECTIVE.: The aim was to assess the visibility of C7 and T1 endplates on radiographs, and to verify the correlation between C7 or T1 slope and cervical balance parameters using kMRI. SUMMARY OF BACKGROUND DATA:Because the T1 slope is not always visible due to the anatomical interference, several studies have used C7 slope instead of T1. However, it is still unclear whether the C7 endplate is more visible on radiographs than T1, and if C7 slope has similarity with T1 slope. METHODS:The endplate visibility was determined using weight-bearing radiography. Subsequently, using weight-bearing MR images, the C7 slope of upper and lower endplate, T1 slope, C1 inclination, C2 slope, atlas-dens interval (ADI), C2-C7 lordotic angle, cervical sagittal vertical axis (cSVA), cervical tilt, cranial tilt, neck tilt, thoracic inlet angle (TIA) were measured, for the analysis of correlation between three types of slopes and cervical balance parameters. RESULTS:82% of the upper C7, and 18% of T1 endplate were clearly visible. The upper C7 endplate was significantly visible, whereas T1 endplate was significantly invisible (residual analysis, P < 0.01). Linear regression analysis showed correlation between the upper C7 slope and T1 slope (R = 0.818, P < 0.01) and, lower C7 slope and T1 slope (R = 0.840, P < 0.01). T1 slope significantly correlated with neck tilt, TIA, C2-C7 angle, cSVA, cervical and cranial tilt, but not with the C1 inclination, C2 slope, and ADI. Upper and lower C7 slopes showed the close resemblance with T1 slope in terms of correlation with those parameters. CONCLUSION:Both, upper and lower C7 slope correlated strongly with T1 slope and showed similar relationship with cervical balance parameters as T1 slope. Therefore, C7 slope could potentially substitute T1 slope, especially upper C7 slope due to the good visibility. LEVEL OF EVIDENCE:3.

STUDY DESIGN/METHODS:Retrospective case study. OBJECTIVE:To evaluate the trends and demographics of recombinant human bone morphogenetic protein 2 (rhBMP2) utilization in single-level anterior lumbar interbody fusion (ALIF) in the United States. METHODS:Patients who underwent single-level ALIF from 2005 to 2011 were identified by searching ICD-9 diagnosis and procedure codes in the PearlDiver Patient Records Database (PearlDiver Technologies, Fort Wayne, IN), a national database of orthopedic insurance records. The year of procedure, age, gender, and region of the United States were analyzed for each patient. RESULTS:< .001), with an incidence of 0.21 per 100 000 patients. CONCLUSIONS:The incidence of rhBMP2 utilization in single-level ALIF increased from 2006 to 2009, but decreased in 2010 and 2011. The Northeast region had the lowest incidence of rhBMP2 utilization. The group aged less than 65 years trended to have the higher incidence of single-level ALIF with rhBMP2 utilization.