Level Anterior Lumbar Interbody Fusion Research Articles

Restoring L4-S1 Lordosis Shape in Severe Sagittal Deformity: Impact of Correction Techniques on Alignment and Complication Profile

Severe sagittal plane deformity with loss of L4-S1 lordosis is disabling and can be improved through various surgical techniques. However, data is limited on the differing ability of anterior lumbar interbody fusion (ALIF), pedicle subtraction osteotomy (PSO), and transforaminal lumbar interbody fusion (TLIF) to achieve alignment goals in severely malaligned patients. To examine surgical techniques aimed at restoring L4-S1 lordosis in severe adult spinal deformity (ASD). Retrospective review of prospectively collected data. A total of 96 patients who underwent ALIF, PSO, and TLIF were included in this study. The following data were observed for all cases: patient demographics, spinopelvic parameters, complications, and PROMs. Severe ASD patients with preoperative PI-LL >20°, L4-S1 lordosis <30°, and full body radiographs and patient-reported outcome measures (PROMs) at baseline and six-week postoperative visit were included. Patients were grouped into ALIF (1-2 level ALIF at L4-S1), PSO (L4/L5 PSO), and TLIF (1-2 level TLIF at L4-S1). Comparative analyses were performed on demographics, radiographic spinopelvic parameters, complications, and PROMs. Among the 96 included patients, 40 underwent ALIF, 27 underwent PSO, and 29 underwent TLIF. At baseline, cohorts had comparable age, sex, race, Edmonton frailty scores and radiographic spinopelvic parameters (p>0.05). However, PSO was performed more often in revision cases (p<0.001). Following surgery, L4-S1 lordosis correction (p=0.001) was comparable among ALIF and PSO patients and caudal lordotic apex migration (p=0.044) was highest among ALIF patients. PSO patients had higher intraoperative estimated blood loss (p<0.001) and motor deficits (p=0.049), and in-hospital ICU admission (p=0.022) and blood products given (p=0.004) but were otherwise comparable in terms of length of stay, blood transfusion given, and postoperative admission to rehab. Likewise, 90-day postoperative complication profiles and six-week PROMs were comparable as well. ALIF can restore L4-S1 sagittal alignment as powerfully as PSO, with fewer intra-operative and in-hospital complications. When feasible, ALIF is a suitable alternative to PSO and likely superior to TLIF for correcting L4-S1 lordosis among patients with severe sagittal malalignment.

Risk Assessment of Anterior Lumbar Interbody Fusion Access in Degenerative Spinal Conditions.

This was a retrospective cohort study. Develop an evidence-based preoperative risk assessment scoring system for patients undergoing anterior lumbar interbody fusion (ALIF). ALIF may hold advantages over other fusion techniques in sagittal restoration and fusion rates, though it introduces unique risks to vascular and abdominal structures and thus possibly increased risk of operative morbidity. Primary, 1 or 2-level ALIFs were identified in a surgical registry. Baseline characteristics were recorded. Axial magnetic resonance imagings at L4-L5 and L5-S1 were reviewed for vascular confluence/bifurcation or anomalous structures, and measured for operative window size/slope. To assess favorable outcomes, a clinical grade was calculated: (clinical grade=blood loss×operative duration), higher value indicating poorer outcome. To establish a risk scoring system, a base risk score algorithm was established and stratified into 5 categories: high, high to intermediate, intermediate, intermediate to low, and low. Modifiers to base risk score included age, body mass index, operative level, history of bone morphogenic protein use, calcified vasculature, spondylolisthesis grade, working window size and slope, and abnormal vasculature. Modifiers were weighted for contribution to surgical risk. A total risk score was calculated and evaluated for strength of association with clinical outcome grades by Pearson correlation coefficient. A total of 65 patients were included. Mean clinical outcome grade was 5.6, mean total risk score 21.3±21.5. Multilevel procedures (L4-S1) mean total risk score was 57.3±7.8. L4-L5 mean total risk score was 23.6±5.2; L5-S1 mean total risk score 8.3±6.6. Correlation analysis demonstrated a significant and strong relationship (| r |=0.753; P <0.001) between total risk scores and clinical outcome grades. Calculated ALIF risk scores significantly correlated with operative duration and blood loss. This scoring system represents a potential framework to facilitate clinical decision-making and risk assessment for potential ALIF candidates with degenerative spinal pathologies.

How old is too old?: Matched analysis of geriatric patients undergoing anterior lumbar interbody fusion

Study designRetrospective Review Introduction/ObjectiveThe aim of this study is to utilize a national database to identify how age affects patient outcomes following anterior lumbar interbody fusion (ALIF). There are no established age guidelines for the geriatric population within the spine specialty, which makes patient selection challenging. Furthermore, there are conflicting studies for the risks of performing spine surgeries in the elderly. MethodsA retrospective review of the Mariner Claims Database was conducted on patients who underwent a single level ALIF (CPT 22558) between 2010 and 2018. Patients were separated into three groups by age: 50–64, 65–74, and 75–84 and matched with respect to gender, smoking, and comorbidity burden. Multivariable logistic regression was used to determine the independent effect of outpatient surgery on the postoperative outcomes after adjusting for demographic factors and pertinent comorbidities. Statistical significance was set at p < 0.05. ResultsThe study identified 8459 matched patients (3350 50–64; 3350 65–74; and 1759 75–84). Compared with patients aged 50–64, patients aged 65–74 and 75–84 had significantly increased risks of pneumonia (65–74: OR 1.53, 95% CI 1.06–2.24, p = 0.025; 75–84: OR 1.62, 95% CI 1.07–2.42, p = 0.022), sepsis (65–74: OR 2.20, 95% CI 1.36–3.76, p = 0.002; 75–84: OR 2.42, 95% CI 1.43–4.13, p = 0.001), and major complications (65–74: OR 1.35, 95% CI 1.05–1.74, p = 0.021; 75–84: OR 1.48, 95% CI 1.11–1.95, p = 0.006) (Table 2). There were no significant differences between patients aged 65–74 and 75–84 for risks of postoperative pneumonia, sepsis, and major complications (p > 0.05). There were no differences between any groups in terms of long-term outcomes such as pseudoarthrosis, implant related complications, or reoperation (p > 0.05) (Table 3). Discussion/ConclusionThe study showed that those older than 65 had a significant increase in risk of pneumonia, sepsis, and major complications following ALIF. In the two cohorts above the age of 65 (65–74 and 75–84) there was no significant differences in postoperative outcomes. Level of evidence3

Osteoporosis is associated with increased minor complications following single level ALIF and PSIF: an analysis of 7,004 patients.

Osteoporosis is a prevalent disease that predisposes patients to fracture and additional post-operative complications, potentially contributing to decreased quality of life. The objective of the current study is to (I) characterize the demographic trends of individuals with osteoporosis undergoing single level posterior spine instrumentation and fusion (PSIF) and anterior lumbar interbody fusion (ALIF); (II) determine the association between osteoporosis and postoperative complications; (III) identify whether the use of bone strengthening medications is associated with improved outcomes. A retrospective review of the Mariner Claims Database was conducted on patients undergoing single level ALIF (CPT 22558) and PSIF (CPT 22840) between 2011 and 2017. Diagnosis of osteoporosis (CPT 77080, CPT 77801, CPT 77082) included a bone density scan within two years of surgery. Patients with osteoporosis were 1:1 matched to controls. Patients taking bone enhancing medications prior to surgery were compared to those that did not take medications. Multivariable logistic regression analyses were performed to evaluate post-operative complication risk factors. 3,502 patients with diagnosed osteoporosis underwent ALIF and PSIF, of which 788 (22.5%) were treated with supplemental medication. Diagnosis of osteoporosis was associated with an increased risk of pulmonary embolism [1.1% vs. 0.4%, odds ratio (OR) 2.48, 95% confidence interval (CI): 1.36-4.53, P=0.003] and minor complications (16.7% vs. 12.9%, OR 1.15, 95% CI: 1.01-1.30, P=0.039). Revision rates two-years post-operatively were not significantly different between patients with osteoporosis and matched controls (P>0.05). There were no differences in outcomes between osteoporotic patients who received medications and those who did not receive medication (P>0.05). Osteoporosis is common in a nationally-representative Medicare database cohort. Pre-operative diagnosis of osteoporosis is associated with increased minor complications following ALIF and PSIF. Pre-operative osteoporosis treatment is not associated with a significant difference in post-operative outcomes. The current study can guide pre-operative counseling in this cohort.

19. Anterior lumbar interbody fusion with porous titanium interbody cages is associated with equivalent fusion rates and patient reported outcomes as bone morphogenetic protein-2

<h3>BACKGROUND CONTEXT</h3> Although frequently used for anterior lumbar interbody fusion (ALIF), concerns regarding the use of recombinant human bone morphogenetic protein 2 (BMP-2) include off-label use, elevated cost and adverse outcomes such as osteolysis. The growing evolution of porous implant technology in promoting osseous integration via ingrowth provides an opportunity for a paradigm shift by relying less on biologic-assisted through-growth and leveraging implant on-growth and in-growth in similar fashion to porous metallic implants used in other orthopedic settings such as hip arthroplasty. <h3>PURPOSE</h3> This study compared perioperative clinical and radiographic outcomes between patients undergoing ALIF with the assistance of BMP-2 in a nonporous, traditional window interbody cage vs those with no biologic using a minimal-window porous titanium interbody cage. <h3>STUDY DESIGN/SETTING</h3> Retrospective clinical. <h3>PATIENT SAMPLE</h3> This study retrospectively examined 75 consecutive patients who underwent 1- or 2-level ALIF between 2014 and 2020 with the use of BMP-2 in a nonporous PEEK cage vs a porous titanium interbody cage and no biologic. All patients had surgery with the senior surgeon and were followed for a minimum follow-up of 6-months postoperatively. <h3>OUTCOME MEASURES</h3> Patient demographics, comorbidities, postoperative complications, and preoperative, immediate and final postoperative patient-reported outcomes (PROs) were assessed. Rates of reoperation were recorded, and arthrodesis was evaluated using Bridwell radiographic criteria and CT when available. Pre- and postoperative radiographic parameters were evaluated for differences in spinopelvic alignment and correction. <h3>METHODS</h3> Statistical methods included student's t-test and chi-square for continuous and categorical variables, respectively. Continuous variables were reported as means and standard deviations, and categorical variables as proportions. The threshold for statistical significance was set to p < .05. <h3>RESULTS</h3> Forty-three (13 female, 30 male) and 32 (19 female, 13 male) patients were assessed in the BMP-2 and titanium cage cohorts, respectively. On PRO assessment, baseline VAS leg among BMP-2 patients (6.87, SD: 1.96 vs 5.16, SD: 2.41; p = .023) while the titanium cage group reported worse VAS back scores (6.23, SD: 2.39 vs 7.82, SD: 1.40; p = .023). However, there were no significant differences recorded in postoperative PRO surveys between groups. Correction of spinopelvic alignment was equally maintained between groups at final follow-up when compared to immediate postoperative radiographs. Similarly, disc spaces were equivalently upheld across cohorts, with the exception of greater degeneration among BMP-2 patients at the L4-L5 anterior (-1.78, SD: 3.00 vs -0.07, SD: 2.63; p = .039) and foraminal (-2.34, SD: 3.11 vs -0.07, SD: 2.06; p = .006) disc spaces. Interbody subsidence was similar at the superior (1.13, SD: 0.84 vs 1.28, SD: 0.88; p = .458) and inferior endplates (0.55, SD: 0.79 vs 0.91, SD: 1.27; p = .154), and radiographic evidence of fusion was observed at equivalent rates (90% vs 90.9%, p = .776). There were no differences in the rates of secondary surgeries for adjacent segment disease (ASD) (4.6% vs 0%, p = .222) or index-level revisions (9.1% vs 18.8%, p = .219). <h3>CONCLUSIONS</h3> Porous titanium interbody cages for ALIF may be equivalent to BMP-2 in nonporous PEEK in achieving arthrodesis, alignment durability and reoperation rates. Although long-term follow-up is necessary, the use of porous titanium implants without external biologics is an intriguing paradigm change which may produce similar outcomes at lower costs. <h3>FDA DEVICE/DRUG STATUS</h3> Alphatec Identiti Cage (Approved for this indication), Recombinant Human Bone Morphogenetic Protein-2 (Approved for this indication)

Safety Profile and Radiographic and Clinical Outcomes of Stand-Alone 2-Level Anterior Lumbar Interbody Fusion: A Case Series of 41 Consecutive Patients.

Objective: The use of stand-alone 2-level anterior lumbar interbody fusion (ALIF) for degenerative lumbar disease has been increasing as an alternative to routinely augmenting these constructs with posterior fixation or fusion. Despite the potential benefits of a stand-alone approach (decreased cost and operative time, decreased pain and early mobilization), there is a paucity of information regarding these operations in the literature. This investigation aimed to determine the safety profile, radiographic outcomes including fusion rates, improvement in preoperative pain, and spinopelvic parameter modification, for patients undergoing stand-alone 2-level ALIF.Methods: This retrospective case series involved a chart review of all patients undergoing 2-level stand-alone ALIF at a single tertiary hospital from 2008 to 2018. Data included patient demographics, hospitalization, complications and radiological studies. Visual analog scale (VAS) back and leg scores were measured via patient-administered surveys preoperatively and up to 18 weeks postoperatively.Results: Forty-one patients who underwent L4-S1 stand-alone ALIF were included. Sixteen (39%) of patients had undergone previous posterior lumbar surgery. Length of stay averaged 4.2 days. Complication rates were comparable to 1-level ALIF. Two patients required reoperation. Fusion rates were 100% for L4-5 and 94.4% for L5-S1. There was no significant change in lumbar lordosis (LL) or LL-pelvic incidence (PI), but there was improved segmental lordosis (SL) and disc height at L4-S1 on final follow-up imaging. There was also modest but statistically significant improvement in VAS back and leg scores.Conclusions: Stand-alone 2-level ALIF is an option for a surgeon to perform in the absence of significant instability, even in the setting of prior posterior surgery. These procedures increase SL and disc height, but do not have the same effect on LL or LL-PI.

P132. Is there a difference in clinical outcomes between single level and two level anterior lumbar interbody fusion for degenerative disc disease?

BACKGROUND CONTEXT Anterior lumbar interbody fusion (ALIF) has shown significant improvements in clinical outcomes for patients with degenerative disc disease causing lower back pain and foraminal stenosis. However, few studies have examined if there is a difference between outcomes in single level vs two level standalone ALIF. PURPOSE The purpose of this study was to assess for a difference in outcomes in single level vs two-level ALIF. STUDY DESIGN/SETTING Retrospective cohort study of patients treated at a single academic institution by a single surgeon. PATIENT SAMPLE Consecutive adult patients from 2011 to 2019 with the diagnosis of degenerative disc disease who underwent a single level (L5-S1) vs two level (L4-S1) standalone ALIF were included in this study. Only patients with 6 months of follow-up were analyzed. OUTCOME MEASURES Patient demographic data including age, body mass index, gender and American Society of Anesthesiologists classification was collected. Visual analog scale (VAS) pain scores for the back and leg, Oswestry Disability Index (ODI), Short Form 12 (SF-12) and Veterans RAND 12 (VR-12) scores were collected for clinical outcomes preoperatively and at the final postoperative visit. METHODS This study was a retrospective review of prospectively collected data. The patients were divided into cohorts of single level vs level ALIFs. Demographic data was compared between the two cohorts to look for baseline differences. Changes between preoperative and final clinical outcomes were compared using bivariate and multivariate linear regressions. Patients who achieved the minimal clinically important difference (MCID) in VAS and ODI scores from both groups were further analyzed with bivariate and multivariate linear regressions to assess for significant differences in outcomes. RESULTS A total of 73 patients were included. Fifty-six (76.7%) underwent a single level ALIF and 17 (23.3%) underwent two level ALIF. There were no baseline differences in patient demographics, nor in preoperative clinical scores. Both cohorts demonstrated improvements in all clinical outcomes postoperatively, and there was no significant difference between either group in bivariate and multivariate regression analysis of the postoperative clinical outcomes. Twenty patients (35.7%) in the single level ALIF cohort and seven patients (41.2%) in the two-level ALIF groups met the MCID cutoffs in VAS and ODI scores, and there was no significant difference between these patients in outcomes. CONCLUSIONS Both single-level L5-S1 and two-level L4-S1 standalone ALIF for degenerative disc disease demonstrate improvements in all clinical outcomes postoperatively. There is no significant difference between patients who underwent a single-level vs two-level stand-alone ALIF. FDA DEVICE/DRUG STATUS This abstract does not discuss or include any applicable devices or drugs.

200. Comparison of freehand, fluoro-guided, CT navigation, and robot-guided TLIF and ALIF

BACKGROUND CONTEXT Screw placement in transforaminal interbody fusion (TLIF) and anterior lumbar interbody fusion (ALIF) can be done with open free hand (FH), fluoroscopy-guided (FG), spinal navigation (NAV), or robotic guided (RG) techniques. Varied techniques may affect perioperative (periop) outcomes. Few studies compare all four guidance techniques. PURPOSE Compare the perioperative outcomes between FH, FG, NAV, and RG TLIF and ALIF. STUDY DESIGN/SETTING Single center retrospective cohort study PATIENT SAMPLE A total of 1,646 patients who underwent 1-2 level TLIF or 1-3 level ALIF from 2012-2019. OUTCOME MEASURES Outcomes: registration failure, operative time (OT), radiation dosage (RD), estimated blood loss (EBL), length of stay (LOS), and periop complications, and retursn to OR up to 90 days. METHODS Patients undergoing 1-2 level TLIF or 1-3 level ALIF were included. Analysis of variance (ANOVA) and χ2test were used to analyze differences in outcomes with significance set at p RESULTS A total of 1,202 1-2 level TLIFs were included (843 FH, 175 FG, 40 NAV, 144 RG) TLIFS. 444 1-3 level ALIFs were included: 337 FH, 25 FG, and 80 RG ALIFs. Demographics were similar amongst ALIF cohorts except significantly more FH-ALIF smokers and TLIF cohorts after propensity matching for levels fused. Amongst the TLIF Cohorts: OT and LOS longest in NAV (291.67±89.85 min; p CONCLUSIONS NAV-TLIF had significantly differences in EBL, RD, periop complications, and return to OR 30 days. PSM for levels fused show postop complications rate remain significant with other factors and radiographic dosage remaining significant. RG TLIF and RG ALIF had the worst perioperative complications. FDA DEVICE/DRUG STATUS This abstract does not discuss or include any applicable devices or drugs.

150. Outpatient vs inpatient anterior lumbar surgery: a multisite, comparative analysis of patient safety measures

BACKGROUND CONTEXT The frequency and complexity of spinal surgery performed in an outpatient setting has been steadily increasing in the past decade. However, data on the safety and efficacy of most spinal procedures adapted to the outpatient setting is lacking. The few studies that have reviewed specific outpatient procedures have mostly focused on anterior cervical surgery, and have drawn conflicting conclusions. To our knowledge, there is no published literature on the feasibility, safety and effectiveness of anterior lumbar surgery (fusions and disc replacements) in an outpatient setting. PURPOSE The purpose of this study is to evaluate the safety and efficacy of outpatient anterior lumbar procedures compared to procedures done at an inpatient setting in a matched cohort of patients. STUDY DESIGN/SETTING This study is a retrospective matched cohort study of patients who underwent an anterior lumbar interbody fusion (ALIF) or a lumbar artificial disc replacement (LADR) at an inpatient facility, compared to a free-standing ambulatory surgery center. PATIENT SAMPLE Consecutive adult patients of several orthopedic and neurosurgical spine surgeons, who underwent elective stand-alone ALIF or LADR or a hybrid of fusion and disc replacement, at either an inpatient tertiary care facility or an outpatient surgical center were studied. A minimum of 90-day follow-up was required. OUTCOME MEASURES Reoperation rates, readmission rates, 90-day complication rates, and length-of-stay data were collected and compared between the two groups. Complications that were specifically assessed included neurological injury, durotomy, vascular injuries, bowel injuries, postoperative ileus, epidural or retroperitoneal hematomas, postoperative urinary retention, urinary tract infections, deep vein thrombosis (DVT), pulmonary embolism (PE), cardio-pulmonary complications, intractable pain, surgical site infection, and death. METHODS Medical records of 231 consecutive patients who underwent ALIF or LADR procedures between 2016-2019 were reviewed. The inpatient and outpatient cohorts were matched with regards to age, sex, body mass index (BMI), and medical comorbidities. Length of stay, complication data, reoperations, and readmissions were recorded and compared between the groups. RESULTS A total of 124 (54%) inpatient and 107 (46%) outpatient patients were reviewed for this study. The two groups had similar baseline characteristics. While there was a trend toward fewer complications, reoperations and readmission for the outpatient cohort, the differences were not statistically significant. The overall 90-day complication rate was 5.6% for the inpatient cohort, and 0.9% for the outpatient cohort. Of the patients in the inpatient cohort, 3.2% were re-admitted within 90 days, compared to 1.9% of those in the outpatient cohort. Reoperation rate was 1.6% for the inpatient cohort. No patient from the outpatient cohort required reoperation. The average hospital stay was 56.9 hours, compared to 5.2 hours at the ambulatory surgery center. CONCLUSIONS There were no statistically significant differences between the 90-day complication and reoperation rates between anterior lumbar procedures performed in an inpatient vs outpatient setting in a matched cohort of patients. Furthermore, the overall 90-day readmission rates were lower for outpatients than for inpatients. Our results support the conclusion that anterior lumbar procedures including 1- and 2-level ALIF and LADR procedures can be performed safely in an outpatient setting. FDA DEVICE/DRUG STATUS This abstract does not discuss or include any applicable devices or drugs.

Adjacent Segment Reoperation and Other Perioperative Outcomes in Patients Who Underwent Anterior Lumbar Interbody Fusions at One and Two Levels

This is the first large retrospective analysis of patients undergoing anterior lumbar interbody fusion (ALIF) with concern for clinical determinants leading to reoperation for adjacent segment disease (ASD). The objective of this study is to examine the specific perioperative and clinical determinants that affect need for adjacent segment reoperation in patients who underwent 1-level and 2-level ALIF procedures for degenerative disc disorders. All cases at our institution between 2008 and 2016 involving an ALIF performed for degenerative disc disorders at 1 or 2 levels were examined. A total of 404 ALIF cases, of which 268 were single-level (66.33%) and 136 were 2-level procedures (33.67%), were included. Adjacent segment reoperation was the primary outcome. Secondary outcomes included increased blood loss, extended surgery duration, greater nonhome discharge, extended hospitalization, and higher total direct costs. Univariate and multivariate logistic regression assessed how number of levels fused related to perioperative outcomes. The patient cohorts shared similar demographic characteristics and showed expected differences in certain intraoperative outcomes. After controlling for preoperative and intraoperative variables, multivariate regression showed that patients who underwent 2-level ALIFs experienced increased odds of adjacent segment reoperation (P= 0.0424) but no other adverse clinical outcomes. Our findings support a biomechanical hypothesis of ASD onset after fusion, suggesting that the risk of ASD after ALIF lies primarily in the number of levels fused rather than any demographic or intraoperative variables.

Use of recombinant human bone morphogenetic protein-2 in spine surgery.

Bone morphogenetic proteins are osteoinductive factors which have gained popularity in orthopaedic surgery and especially in spine surgery. The use of recombinant human bone morphogenetic protein-2 has been officially approved by the United States Food and Drug Administration only for single level anterior lumbar interbody fusion, nevertheless it is widely used by many surgeons with off-label indications. Despite advantages in bone formation, its use still remains a controversial issue and several complications have been described by authors who oppose their wide use.

Thirty-day readmission rate and risk factors for patients undergoing single level elective anterior lumbar interbody fusion (ALIF)

Anterior lumbar interbody fusion (ALIF) represents a common interbody fusion technique and is advantageous given reduced risk of damage to the paraspinal muscles, posterior ligaments, and neural elements. In this study, we identified the readmission rate, common causes, and risk factors associated with single level ALIF 30-day readmission. Patients who underwent elective single level ALIF surgery from 2011 to 2013 were identified in the American College of Surgeons–National Surgical Quality Improvement Program (ACS–NSQIP) database. Segmental fusion, emergency, and trauma cases were excluded. A total of 2,042 patients were identified from the ACS-NSQIP database from 2011 to 2013. The proportion of patients readmitted was 5.19% (106/2,042) and approximately 59.81% (64/106) had a reportable cause. The top three causes were poor post-operative pain control (11%), deep (9%) and superficial (9%) surgical site infections. Risk factors associated with 30-day readmission included age (odds ratio (OR)=1.02, 95% confidence interval (CI): 1.00–1.03, p value=0.05), history of severe chronic obstructive pulmonary disease (COPD), (OR=2.11, 95% CI: 0.95–4.70, p value=0.08), post-operative pneumonia (OR=6.58, 95% CI: 2.36–18.30, p value<0.001), and presence of superficial surgical site infection (OR=11.68, 95% CI: 4.88–27.95, p value<0.001). Bleeding disorders, anemia, and perioperative blood loss was not associated with 30-day readmission. Limitations include retrospective level 3 data, and missing data. This study represents the first nation-wide descriptive evaluation of 30-day readmission causes and risk factors for patients undergoing an ALIF procedure.

Effect of Anatomic Variability and Level of Approach on Perioperative Vascular Complications With Anterior Lumbar Interbody Fusion.

Retrospective review of prospectively collected data. The study aim was to determine the prevalence of vascular complications associated with anterior lumbar interbody fusion (ALIF) as a function of anatomic variation and the number of levels fused. ALIF often requires mobilization of the great vessels, particularly when exposing levels above L5-S1. The exposure can be more challenging in the setting of spondylolisthesis or transitional anatomy. This retrospective review of prospectively collected data from our spine database identified 204 patients who had undergone single level (n = 142) or multilevel (n = 62) ALIF from 2008 to 2013 with minimum 6-month follow-up. Average age was 58 years; 57% were female. Preoperative radiographic assessment for spondylolisthesis and transitional anatomy was performed. Body mass index, estimated blood loss, and levels of ALIF were recorded. Intraoperative vascular injury, postoperative deep venous thrombosis, and pulmonary embolism events were noted. Eleven patients experienced postoperative thromboembolic events and were more likely to have had intraoperative vascular injury compared with patients who did not develop a vascular complication (36% and 5%, respectively; P = 0.004). Estimated blood loss was significantly higher in patients with spondylolisthesis when compared to patients without spondylolisthesis (520 cc vs. 103 cc, respectively; P = 0.017) or transitional anatomy (347 cc vs. 262 cc, respectively; P = 0.022). Patients undergoing multilevel ALIF had significantly higher blood loss than patients undergoing a single level procedure (684 cc vs. 107 cc; P < 0.001). Patient characteristics, blood loss, anatomic variation, and level of approach were not associated with the development of postoperative thromboembolic complications. Performing ALIF in the setting of spondylolisthesis or transitional anatomy resulted in higher blood loss. Patients undergoing multilevel rather than single level ALIF experienced greater blood loss. Because patients with intraoperative vascular injury had increased likelihood of postoperative thromboembolic event, thrombosis prophylaxis should be considered in these patients. 4.

Minimally invasive anterior lumbar interbody fusion for adult degenerative scoliosis with 1 or 2 dislocated levels.

Frequent complications of posterolateral instrumented fusion have been reported after treatment of degenerative scoliosis in elderly patients. Considering that in some cases, most of the symptomatology of adult degenerative scoliosis (ADS) is a consequence of the segmental instability at the dislocated level, the use of minimally invasive anterior lumbar interbody fusion (ALIF) to manage symptoms can be advocated to reduce surgical morbidity. The purpose of this study was to evaluate the midterm outcomes of 1- or 2-level minimally invasive ALIFs in ADS patients with 1- or 2-level dislocations. A total of 47 patients (average age 64 years; range 43-80 years) with 1- or 2-level ALIF performed for ADS (64 levels) in a single institution were included in the study. An independent spine surgeon retrospectively reviewed all the patients' medical records and radiographs to assess operative data and surgery-related complications. Clinical outcome was reported using the Oswestry Disability Index (ODI) and the visual analog scale (VAS) for lumbar and leg pain. Intraoperative data and complications were collected. Fusion and risk for adjacent-level degeneration were assessed. The mean follow-up duration was 3 years (range 1-10 years). ODI, and back and leg pain VAS scores were significantly improved at last follow-up. A majority of patients (74%) had a statistically significant improvement in their ODI score of more than 20 points at latest follow-up and 1 had a worsening of his disability. The mean operating time was 166 minutes (range 70-355 minutes). The mean estimated blood loss was 410 ml (range 50-1700 ml). Six (5 major and 1 minor) surgical complications (12.7% of patients) and 13 (2 major and 11 minor) medical complications (27.7% of patients) occurred without death or wound infection. Fusion was achieved in 46 of 47 patients. Surgery resulted in a slight but significant decrease of the Cobb angle, and improved the pelvic parameters and lumbar lordosis, but had no effect on the global sagittal balance. At latest follow-up, 9 patients (19.1%) developed adjacent-segment disease at a mean of 2 years' delay from the index surgery; 4 were symptomatic but treated medically, and none required iterative surgery. Single- or 2-level minimally invasive fusion through a minimally invasive anterior approach in some selected cases of ADS produced a good functional outcome with a high fusion rate. They were associated with a significantly lower rate of complications in this study than the historical control.

Epidemiologic trends in the utilization, demographics, and cost of bone morphogenetic protein in spinal fusions.

Bone morphogenetic protein (BMP) utilization as an adjunct for spinal arthrodesis has gained considerable momentum among spine surgeons. Despite carrying Food and Drug Administration approval for only single level anterior lumbar interbody fusion from L4-S1, the majority of BMP administration is in "off label" settings. Over the last decade, BMP utilization has increased in all facets of spine surgery with the only exception being the anterior cervical spine, in which a downward trend resulted following the 2008 Food and Drug Administration warnings. The future application of BMP in spinal fusion, especially in anterior cervical fusions, will need to be further clarified in terms of efficacy, complications, and cost-effectiveness.

A review of the current published spinal literature regarding bone morphogenetic protein-2: an insight into potential bias.

Recombinant human bone morphogenetic protein-2 (rhBMP-2) is a potent biologic agent that carries both osteoinductive and osteoconductive properties. Its potential as an autologous bone graft substitute in spine surgery led to its approval by the United States Food and Drug Administration (FDA) in 2002 following a series of industry-sponsored trials. Although approved for a single level anterior lumbar interbody fusion from L4-S1 with a proprietary cage, the off-label use of rhBMP-2 rapidly escalated. Soon thereafter, reports of serious and potentially life-threatening complications associated with rhBMP-2 began emerging, which sparked concerns with regards to potential bias in the original FDA trials. Ultimately, an independent review of all published and unpublished data on the safety and effectiveness of rhBMP-2 by the Yale University Open Data Access (YODA) Project determined that while rhBMP-2 is as effective as iliac crest bone graft (ICBG) in potentiating spinal fusion, there was significant bias and conflicts of interests that resulted in an underreporting of complications in the original industry-sponsored trials.

What is the Rate of Lumbar Adjacent Segment Disease after Percutaneous versus Open Fusion?

Adjacent segment disease (ASD) requiring treatment or re-operation is a common problem after surgery on the lumbar spine. The hypothesis of this retrospective study was that ASD occurs less often following lumbar spine fusion in patients who undergo percutaneous minimally invasive (MIS) instrumentation than in those in whom open instrumentation is used. A case-control study was performed on consecutive patients who had undergone staged single or two level anterior lumbar interbody fusion for degenerative conditions followed by open or MIS instrumentation from 2002 to 2005 in our institution. ASD was defined as that necessitating additional procedures for new symptoms related to an adjacent lumbar dermatome. One hundred and seventeen patients met the inclusion criteria. Of these, 53 had been followed up by chart or medical record review for longer than one year. There were 23 patients in the MIS group and 30 in the open group. Of the 30 patients in the open group, 9 had developed ASD (30%). Of the 23 patients in the MIS group, 7 had developed ASD (30%). This difference is not statistically significant (P = 1.00). Contrary to our hypothesis, there was no significant difference in incidence of ASD in patients who had underwent open versus percutaneous instrumentation following anterior lumbar interbody fusion.

Access related complications in anterior lumbar surgery performed by spinal surgeons

Anterior lumbar surgery is a common procedure for anterior lumbar interbody fusion (ALIF) and artificial disc replacement (ADR). Our aim was to study the exposure related complications for anterior lumbar spinal surgery performed by spinal surgeons. A retrospective review was performed for 304 consecutive patients who underwent anterior lumbar spinal surgery over 10 years (2001-2010) at our institution. Each patient's records were reviewed for patients' demographics, diagnosis, level(s) of surgery, procedure and complications related to access surgery. Patients undergoing anterior lumbar access for tumour resection, infection, trauma and revision surgeries were excluded. All patients underwent an anterior paramedian retroperitoneal approach from the left side. The mean age of patients was 43 years (10-73; 197 males, 107 females). Indications for surgery were degenerative disc disease (DDD 255), degenerative spondylolisthesis (23), scoliosis (18), iatrogenic spondylolisthesis (5) and pseudoarthrosis (3). The procedures performed were single level surgery--L5/S1 (n = 147), L4/5 (n = 62), L3/4 (n = 7); two levels--L4/5 and L5/S1 (n = 74), L3/4 and L4/5 (n = 4); three levels--L3/4, L4/5, L5/S1 (n = 5); four levels--L2/3, L3/4, L4/5, L5/S1 (n = 5). The operative procedures were single level ADR (n = 131), a single level ALIF (n = 87) with or without posterior fusion, two levels ALIF (n = 54), two levels ADR (n = 14), a combination of ADR/ALIF (n = 10), three levels ALIF (n = 1), three levels ADR/ALIF/ALIF (n = 1), ADR/ADR/ALIF (n = 2), four levels ALIF (n = 1) and finally 3 patients underwent a four level ADR/ADR/ALIF/ALIF. The overall complication rate was 61/304 (20 %). This included major complications (6.2 %)--venous injury requiring suture repair (n = 14, 4.6 %) and arterial injury (n = 5 [1.6 %], 3 repaired, 2 thrombolysed). Minor complications (13.8 %) included venous injury managed without repair (n = 5, 1.6 %), infection (n = 13, 4.3 %), incidental peritoneal opening (n = 12, 3.9 %), leg oedema (n = 2, 0.6 %) and others (n = 10, 3.3 %). We had no cases of retrograde ejaculation. We report a very thorough and critical review of our anterior lumbar access surgeries performed mostly for DDD and spondylolisthesis at L4/5 and L5/S1 levels. Vascular problems of any type (24/304, 7.8 %) were the most common complication during this approach. The incidence of major venous injury requiring repair was 14/304 (4.6 %) and arterial injury 5/304 (1.6 %). The requirement for a vascular surgeon with the vascular injury was 9/304 (3 %; 5 arterial injuries; 4 venous injuries). This also suggests that the majority of the major venous injuries were repaired by the spinal surgeon (10/14, 71 %). Our results are comparable to other studies and support the notion that anterior access surgery to the lumbar spine can be performed safely by spinal surgeons. With adequate training, spinal surgeons are capable of performing this approach without direct vascular support, but they should be available if required.

A Surgical Option for Multilevel Anterior Lumbar Interbody Fusion with Ponte Osteotomy to Achieve Optimal Lumbar Lordosis and Sagittal Balance

ObjectiveTo document lumbar lordosis (LL) of the spine and its change during surgeries with the different height but the same angle setting of the anterior cage. Additionally, we attempted to determine if sufficient LL is achieved at different cage heights and to quantify the change in LL during multi-level anterior lumbar interbody fusion (ALIF).MethodsThe medical records and radiographs of 42 patients who underwent more than 2 level ALIFs between 2008 and 2009 were retrospectively reviewed. We evaluated 3 parameters seen on lateral whole spine radiographs : LL, pelvic incidence (PI), and sagittal vertical axis (SVA). The mean follow-up time was 28.1 months and the final follow-up radiographs of all patients were reviewed at least 2 years after surgery. Statistical analysis was performed using the paired t-tests.ResultsLumbar lordosis had changed up to 30 degrees immediately and 2 years after surgery (preoperative mean LL, SVA : 22.45 degrees, 112.31 mm; immediate postoperative mean LL, SVA : 54.45 degrees, 37.36 mm; final follow-up mean LL, SVA : 49.56 degrees, 26.95 mm). Our goal of LL is to obtain as much PI as possible, preoperative mean PI value was 55.38±3.35. The pre-operative and two year post-surgery follow-up mean of the Japanese Orthopedic Association score were 9.2±0.6 and 13.2±0.6 (favorable outcome rate : 95%), respectively. In addition, we were able to obtain good clinical outcomes and sagittal balance with a subsidence rate of 22.7%.ConclusionWe were able to achieve sufficient LL, such that it was similar to the PI, utilizing multi-level ALIF with the use of a tall cage with the same angle setting of the cage. We have found out that achieving sufficient lumbar lordosis and sagittal balance require an anterior lumbar cage with high angle and height.

Anterior Lumbar Interbody Implants: Importance of the Interdevice Distance

Object. The implantation of interbody fusion cages allows for the restoration of disc height and the enlargement of the neuroforaminal space. The purpose of this study was to compare the extent of subsidence occurring after conventional cage placement compared to a novel wider cage placement technique. Methods. This study is a retrospective evaluation of radiographs of patients who underwent stand-alone single level anterior lumbar interbody fusion with lordotic titanium cages and rhBMP-2. Fifty-three patients were evaluated: 39 patients had wide cage placement (6 mm interdevice distance) and 14 had narrow cage placement (2 mm interdevice distance). Anterior and posterior intervertebral disc space heights were measured post-operatively and at follow-up imaging. Results. The decrease in anterior intervertebral disc space height was 2.05 mm versus 3.92 mm (P < .005) and 1.08 mm versus 3.06 mm in posterior disc space height for the wide cage placement and the narrow cage placement respectively. The proportion of patients with subsidence greater than 2 mm was 41.0% in the wide cage patients and 85.7% for the narrow cage patients (P < .005). Conclusions. The wider cage placement significantly reduced the amount of subsidence while allowing for a greater exposed surface area for interbody fusion.