Background and Objectives: As the oblique lateral interbody fusion at L5/S1 (OLIF51) and the lateral corridor approach (LCA) have gained popularity, an understanding of the precise vascular structure at the L5/S1 level is indispensable. The objectives of this study were to investigate the vascular anatomy at the L5/S1 level, and to compare the movement of vascular tissue between the supine and lateral decubitus positions using intraoperative enhanced CT and MRI. Materials and Methods: A total of 43 patients who underwent either OLIF51 or LCA were investigated with an average age at surgery of 60.4 (37-80) years old. The preoperative MRI was taken to observe the axial and sagittal anatomy of the vascular position under the supine position. The intraoperative vein-enhanced CT was taken just before incision in the right decubitus position, and compared to supine MRI anatomy. Iliolumbar vein appearance and its types were also classified. Results: The average vascular window allowed for OLIF51 was 22.8 mm and 34.1 mm at either the L5 caudal endplate level or the S1 cephalad endplate level, respectively. The LCA was 14.2 mm and 12.6 mm at either level, respectively. The left common iliac vein moved 3.8 mm and 6.9 mm to the right direction at either level from supine to the right decubitus position, respectively. The bifurcation moved 6.3 mm to the caudal direction from supine to right decubitus. The iliolumbar vein was located at 31 mm laterally from the midline, and the MRI detection rate was 52%. Conclusions: The precise measurement of vascular anatomy indicated that the OLIF51 approach was the standard minimally invasive anterior approach for the L5/S1 disc level compared to LCA; however, there were many variations in quantitative anatomy as well as significant vascular movements between the supine and right decubitus positions. In the clinical setting of OLIF51 and LCA surgeries, careful preoperative evaluation and intraoperative 3D imaging are recommended for safe and accurate surgery.

BACKGROUND: Anterior lumbar fusion procedures have many benefits and continue to grow in popularity. The technique has many potential approach- and procedure-related complications. Symptomatic retroperitoneal fluid collections are uncommon but potentially serious complications after anterior lumbar procedures. Collection types include hematomas, urinomas, chyloperitoneum, cerebrospinal fluid collections, and deep infections.
METHODS: The authors present an unusual case of a patient with persistent symptoms related to a retroperitoneal collection over a 5-year period following anterior lumbar fusion surgery. To the authors\' knowledge, no similar case with such extensive symptom duration has been described. The patient had an infected encapsulated fluid collection. The collection was presumed to be a postoperative lymphocele that was secondarily infected after serial percutaneous drainage procedures.
CONCLUSIONS: When retroperitoneal collections occur after anterior retroperitoneal approaches, clinical clues, such as timing of symptoms, hypotension, acute anemia, urinary tract infection, hydronephrosis, elevated serum creatinine and blood urea nitrogen, low-pressure headaches, anorexia, or systemic signs of infection, can help narrow the differential. Retroperitoneal collections may continue to be symptomatic many years after anterior lumbar surgery. The collections may become infected after serial percutaneous drainage or prolonged continuous drainage. Encapsulated, infected fluid collections typically require surgical debridement of the capsule and its contents.

Lumbar spinal fusion is one of the most common operations in spinal surgery. For its implementation, anterolateral (pre-psoas) approach (oblique lumbar interbody fusion, OLIF) is now increasingly used due to its high efficacy and safety. However, there is still little information on the clinical and radiological results of using this technique. The aim of the study was to analyze the safety and efficacy of OLIF in the treatment of lumbar spine disorders as presented in the literature.
The systematic electronic search was performed using the Ovid Medline, PubMed, and eLIBRARY.RU electronic databases. The following search key words were used: Oblique Lumbar Interbody Fusion, OLIF, Anterior to Psoas Lumbar Interbody Fusion, and ATP.
For the final analysis, 17 sources were selected; with a total of 2900 patients. Total complication rate was 13.9% (403 cases). The incidence of severe persistent complications was less than 1%. Based on the data obtained, we compared the clinical and radiological results of OLIF with other lumbar fusion methods.
OLIF is an effective, versatile, and minimally traumatic option for lumbar fusion with relatively few complications, which makes it superior to other retroperitoneal approaches. However, the OLIF technique is not completely free of complications associated with the ventral approach, and it cannot provide adequate decompression of the spinal canal in all cases. In addition, anterior approach surgery is still of limited use in cases of spinal deformities; adequate correction of deformity is achievable mainly in combination with posterior surgery.

UNASSIGNED: High-grade spondylolisthesis (>50% slippage) is infrequently encountered in adults and frequently requires surgical treatment. The optimal surgical treatment is controversial with limited literature guidance as to optimal approach to treatment. An observational study to examine the technique and radiographic outcomes of adult patients treated with anterior lumbar interbody fusion (ALIF) and posterior percutaneous instrumentation for high-grade spondylolisthesis.
UNASSIGNED: ALIF was performed in 5 consecutive patients (3/5 female, 2/5 male) aged 29-67 years old who presented with low back pain and L5 radiculopathy. All patients failed conservative treatment and were treated with L4-5 and L5-S1 ALIF followed by posterior percutaneous L4-S1 pedicle screw and rod fixation. Pre- and postoperative clinical data was collected including L5-S1 posterior disk height in millimeters, millimeters of spondylolisthesis at L5-S1, degrees of segmental lordosis (L4-S1), lumbar lordosis (L1-S1), and lumbar lordosis pelvic incidence (LL-PI) mismatch.
UNASSIGNED: Six weeks following surgery, no patient reported residual L5 radicular symptoms. At last follow up, patient satisfaction, according to Modified Macnab Criteria, was excellent in 4/5 patients and good in 1/5 patient. In the 4 patients with greater than 1 year radiographic follow up, fusion rate was 100% on computed tomography (CT). Mean increase in posterior disk height was 12.5 mm (range, 11.4-13.5 mm). Mean reduction in spondylolisthesis was 58.7% (range, 20.2-100%). Mean segmental (L4-S1) and overall (L1-S1) lumbar lordosis increased by 23.6% (range, 6.5-41.7%) and 16.6% (2.5-31.5%), respectively. Following surgery, LL-PI mismatch decreased from a mean of 16.4 to 10.2 degrees.
UNASSIGNED: ALIF with posterior percutaneous instrumentation is a safe and effective treatment for high-grade lumbosacral spondylolisthesis in properly selected adults. This technique improves lumbar sagittal parameters and reduces spondylolisthesis. The indirect neural decompression from simultaneous disk height restoration and spondylolisthesis reduction may be associated with lower neurological injury rate compared to posterior-only. Future prospective study is needed to validate this hypothesis.

Chronic opioid use (COU) remains on the rise globally, acting as a marker for patient morbidity and a risk factor for adverse health outcomes. Opioid use is a risk factor for respiratory depression, which may lead to dysfunctional breathing, a known cause of atelectasis. The objective of this study was to determine whether COU is associated with increased rates of postoperative atelectasis among patients undergoing lumbar fusion.
Three State Inpatient Databases were used to identify patients who underwent an elective lumbar fusion through an anterior, posterior or circumferential approach in Florida, Kentucky and New York between 2013-2015. Patients with COU and those with postoperative atelectasis were identified using ICD diagnosis codes. Three operative groups were created and subsequently matched using propensity scores in order to provide comparable cohorts for analysis. Three-to-one propensity score matching was conducted using the variables of age, sex, race, number of chronic diagnoses and geographic state of admission. Multivariable logistic regressions were used to examine the relationship between COU and postoperative atelectasis.
A total of 3618 lumbar fusions were identified. Atelectasis was noted in 1.33 % of NCOU patients and 2.32 % of COU patients. On multivariable analysis, while controlling for the Elixhauser Mortality Index and patient insurance status, COU was significantly associated with atelectasis in posterior lumbar fusion (OR = 2.27; CI: 1.09-4.72; p = 0.028) and circumferential lumbar fusion (OR = 4.68; CI: 1.52-14.45; p = 0.007). The Elixhauser Mortality Index was also significantly associated with atelectasis in posterior lumbar fusion (OR = 1.08; CI: 1.04-1.11; p < 0.001) and circumferential lumbar fusion (OR = 1.09; CI: 1.03-1.16; p = 0.002).
Higher rates of postoperative atelectasis were found among patients with COU following posterior and circumferential lumbar fusions. The Elixhauser Mortality Index was also independently associated with atelectasis. Knowledge of these risks may allow for earlier identification and intervention in patients who are at risk.

OBJECTIVE: To examine the effects of chronic preoperative steroid therapy on 30-day perioperative complications after anterior lumbar fusion (ALF).
METHODS: We retrospectively analyzed data from the American College of Surgeons National Surgical Quality Improvement Program between 2008 and 2015. Adult patients who underwent ALF were included and divided into 2 groups: steroids and no steroids. We compared baseline patient demographics, comorbidities, and operative variables between these 2 groups and then performed a multivariate regression analysis to determine complications that were independently associated with chronic steroid therapy. We also performed a subgroup analysis of the steroid group to identify additional risk factors that further predispose these patients to postoperative complications.
RESULTS: A total of 9483 patients were included, of whom 289 (3.0%) were on chronic steroid therapy. Univariate analysis showed that chronic steroid use was independently associated with 4 perioperative complications, including deep surgical site infection (odds ratio [OR], 2.78; confidence interval [CI], 1.09-7.10; P = 0.033), pulmonary complications (OR, 1.98; CI, 1.02-3.86; P = 0.044), blood transfusion (OR, 1.60; CI, 1.15-2.23; P = 0.005), and extended length of stay (OR, 1.58; CI, 1.17-2.16; P = 0.003). In patients on chronic steroid therapy, pulmonary comorbidity and extended operative time were additional risk factors that further predisposed to perioperative complications, including deep surgical site infection, blood transfusion, and extended length of stay.
CONCLUSIONS: Chronic preoperative steroid therapy is associated with perioperative complications after ALF. Decisions about the discontinuing or holding steroid therapy preoperatively should be determined through an interdisciplinary approach between the medical and surgical teams.

OBJECTIVE: Anterior lumbar fusion (ALF) is performed by both neurosurgeons and orthopaedic surgeons. The aim of this study was to determine differences between the 2 surgical subspecialties in terms of patient selection and postoperative outcomes after ALF.
METHODS: A retrospective cohort study of adult patients undergoing ALF in the American College of Surgeons National Surgical Quality Improvement Program database from 2010 to 2014 was performed. Univariate analyses were performed to identify differences in baseline patient demographics, comorbidities, operative characteristics, and 30-day postoperative outcomes between neurosurgery and orthopaedic surgery patients. Multivariate logistic regression analysis was used to determine whether surgical subspecialty was an independent risk factor for postoperative complications.
RESULTS: The study included 3182 patients, with 1629 (51.2%) neurosurgery patients and 1553 (48.8%) orthopaedic surgery patients. A greater proportion of neurosurgery patients were >65 years old, were being treated with preoperative steroids, had cardiac or pulmonary comorbidities, and had an American Society of Anesthesiologists classification III or higher. ALF procedures performed by neurosurgeons more frequently involved use of intervertebral devices and bone graft. On multivariate logistic regression analysis, ALF procedures performed by neurosurgeons were independently associated with a higher risk of reoperation (odds ratio = 1.61; 95% confidence interval, 1.02-2.56; P = 0.042) and urinary tract infection (odds ratio = 1.94; 95% confidence interval, 1.02-3.68; P = 0.043).
CONCLUSIONS: In addition to differences in baseline patient demographics and comorbidities and operative characteristics, ALF performed by neurosurgeons had a higher risk of 30-day reoperation and urinary tract infection compared with ALF performed by orthopaedic surgeons.

OBJECTIVE: To identify independent risk factors, additional length of stay, and additional cost associated with postoperative ileus following anterior lumbar interbody fusion in elderly patients.
METHODS: The PearlDiver Patient Records Database was queried for all Medicare patients ≥65 years of age undergoing 1- or 2-level primary elective anterior lumbar interbody fusion from 2005 to 2014. Independent risk factors, additional length of stay, and additional cost associated with postoperative ileus were evaluated with multivariate analysis.
RESULTS: There were 13,139 patients identified, and 642 patients experienced postoperative ileus within 3 days after surgery. Multivariate analysis identified perioperative fluid or electrolyte imbalance (odds ratio = 4.03; 95% confidence interval, 3.37-4.80; P < 0.001) and male sex (odds ratio = 1.72; 95% confidence interval, 1.48-2.00; P < 0.001) as independent risk factors for ileus. Multivariate analysis associated postoperative ileus with additional length of stay of 2.83 ± 0.11 days (P < 0.001) and additional cost of $2,349 ± $419 (P < 0.001).
CONCLUSIONS: Patients with perioperative fluid and electrolyte imbalances were 4 times as likely to experience postoperative ileus. Fluid balance and electrolyte levels should be carefully monitored during the perioperative period in patients undergoing anterior lumbar interbody fusion as a potential means to reduce the incidence of postoperative ileus and the additional length of stay and cost burden associated with this complication.

METHODS: Retrospective cohort study.
OBJECTIVE: To determine if membership in a high-risk subgroup is predictive of morbidity and mortality following anterior lumbar fusion (ALF).
METHODS: The American College of Surgeons National Surgical Quality Improvement Program database was utilized to identify patients undergoing ALF between 2010 and 2014. Multivariate analysis was utilized to identify high-risk subgroup membership as an independent predictor of postoperative complications.
RESULTS: Members of the elderly (≥65 years) (OR = 1.3, P = .02) and non-Caucasian (black, Hispanic, other) (OR = 1.7, P < .0001) subgroups were at greater risk for a LOS ≥5 days. Obese patients (≥30 kg/m2 ) were at greater risk for an operative time ≥4 hours (OR = 1.3, P = .005), and wound complications (OR = 1.8, P = .024) compared with nonobese patients. Emergent procedures had a significantly increased risk for LOS ≥5 days (OR = 4.9, P = .021), sepsis (OR = 14.8, P = .018), and reoperation (OR = 13.4, P < .0001) compared with nonemergent procedures. Disseminated cancer was an independent risk factor for operative time ≥4 hours (OR = 8.4, P < .0001), LOS ≥5 days (OR = 15.2, P < .0001), pulmonary complications (OR = 7.4, P = .019), and postoperative blood transfusion (OR = 3.1, P = .040).
CONCLUSIONS: High-risk subgroup membership is an independent risk factor for morbidity following ALF. These groups should be targets for aggressive preoperative optimization, and quality improvement initiatives.

We analyzed the lumbosacral segmental geometry and clinical outcome in patients undergoing L5 corpectomy.
Fourteen consecutive patients who underwent L5 (n = 12) or L4 + 5 (n = 2) corpectomy at our department between January 2010 and April 2015 were included. All patients underwent a baseline physical and neurologic examination on admission. The diagnostic routine included MRI and CT scans and, if possible, an upright X-ray of the lumbar spine before and after surgery. The local lordosis angle [L4(L3)-S1] was measured.
The most common pathology was infection (N = 7), followed by neoplastic disease (n = 3), pseudarthrosis (n = 2) after previous spinal fusion procedures and burst fractures (n = 2) of the L5 vertebral body. We observed seven complications (2 intraoperative; 5 postoperative) in five (36%) patients. Three patients needed revision surgery because of cage subsidence and/or dislodgement (21%). Additional anterior plating was used in two of the revision surgeries to secure the cage. Two spondylodiscitis patients (14%) with complications died of sepsis. Of the 12 remaining patients, 8 were available for follow-up.
L5 corpectomy is a technically challenging but feasible procedure even though the overall complication rate can be as high as 36%. The radiologic and clinical outcome seems to be better in patients with a small lordosis angle between L4(L3) and S1, since an angle of >50 degrees seems to facilitate cage dislodgement. Anterior plating should be considered in these cases to prevent implant failure.