Faculty Bibliography

STUDY DESIGN/METHODS:Single institution retrospective clinical review. OBJECTIVE:To investigate the relationship between levels fused and clinical outcomes in patients undergoing open and minimally invasive surgical (MIS) lumbar fusion. SUMMARY OF BACKGROUND DATA/BACKGROUND:Minimally invasive spinal fusion aims to reduce the morbidity associated with conventional open surgery. As multilevel arthrodesis procedures are increasingly performed using MIS techniques, it is necessary to weigh the risks and benefits of multilevel MIS lumbar fusion as a function of fusion length. METHODS:Patients undergoing <4 level lumbar interbody fusion were stratified by surgical technique (MIS or open), and grouped by fusion length: 1-level, 2-levels, 3+ levels. Demographics, Charlson Comorbidity Index (CCI), surgical factors, and perioperative complication rates were compared between technique groups at different fusion lengths using means comparison tests. RESULTS:Included: 361 patients undergoing lumbar interbody fusion (88% transforaminal, 14% lateral; 41% MIS). Breakdown by fusion length: 63% 1-level, 22% 2-level, 15% 3+ level. Op-time did not differ between groups at 1-level (MIS: 233 min vs. Open: 227, P = 0.554), though MIS at 2-levels (332 min vs. 281) and 3+ levels (373 min vs. 323) were longer (P = 0.033 and P = 0.231, respectively). While complication rates were lower for MIS at 1-level (15% vs. 30%, P = 0.006) and 2-levels (13% vs. 27%, P = 0.147), at 3+ levels, complication rates were comparable (38% vs. 35%, P = 0.870). 3+ level MIS fusions had higher rates of ileus (13% vs. 0%, P = 0.008) and a trend of increased adverse pulmonary events (25% vs. 7%, P = 0.110). MIS was associated with less EBL at all lengths (all P < 0.01) and lower rates of anemia at 1-level (5% vs. 18%, P < 0.001) and 2-levels (7% vs. 16%, P = 0.193). At 3+ levels, however, anemia rates were similar between groups (13% vs. 15%, P = 0.877). CONCLUSION/CONCLUSIONS:MIS lumbar interbody fusions provided diminishing clinical returns for multilevel procedures. While MIS patients had lower rates of perioperative complications for 1- and 2-level fusions, 3+ level MIS fusions had comparable complication rates to open cases, and higher rates of adverse pulmonary and ileus events. LEVEL OF EVIDENCE/METHODS:3.

Background/UNASSIGNED:Regional and segmental changes of the lumbar spine have previously been described as patients transition from standing to sitting; however, alignment changes in the cervical and thoracic spine have yet to be investigated. So, the aim of this study was to assess cervical and thoracic regional and segmental changes in patients with thoracolumbar deformity versus a nondeformed thoracolumbar spine population. Methods/UNASSIGNED:This study was a retrospective cohort study of a single center's database of full-body stereoradiographic imaging and clinical data. Patients were ≥ 18 years old with nondeformed spines (nondegenerative, nondeformity spinal pathologies) or thoracolumbar deformity (ASD: PI-LL > 10°). Patients were propensity-score matched for age and maximum hip osteoarthritis grade and were stratified by Scoliosis Research Society (SRS)-Schwab classification by PI-LL, SVA, and PT. Patients with lumbar transitional anatomy or fusions were excluded. Outcome measures included changes between standing and sitting in global alignment parameters: sagittal vertical axis (SVA), pelvic incidence minus lumbar lordosis (PI-LL), pelivc tilt (PT), thoracic kyphosis, cervical alignment, cervical SVA, C2-C7 lordosis (CL), T1 slop minus CL (TS-CL), and segmental alignment from C2 to T12. Another analysis was performed using patients with cervical and thoracic segmental measurements. Results/UNASSIGNED: = .009) segments. Conclusions/UNASSIGNED:Nondeformity patients and ASD patients have significant differences in mobility of global spinopelvic parameters as well as segmental regions in the cervical and thoracic spine between sitting and standing. This study aids in our understanding of flexibility and compensatory mechanisms in deformity patients, as well as the possible impact on unfused segments when considering deformity corrective surgery.

Study Design/UNASSIGNED:Retrospective study of consecutive patients at a single institution.Objective: Examine the effect of minimally invasive surgery (MIS) versus open transforaminal lumbar interbody fusion (TLIF) surgery on long-term postoperative narcotic consumption. Objective/UNASSIGNED:Examine the effect of minimally invasive versus open TLIF on short-term postoperative narcotic consumption. Methods/UNASSIGNED:Differences between MIS and open TLIF, including inpatient opioid and nonopioid analgesic use, discharge opioid use, and postdischarge duration of narcotic usage were compared using appropriate statistical methods. Results/UNASSIGNED:= .018) compared with MIS TLIF. Conclusion/UNASSIGNED:Patients undergoing MIS TLIF required less inpatient opioids and had a decreased incidence of opioid dependence at 3-month follow-up. Patients with preoperative opioid use undergoing MIS TLIF are less likely to require long-term opioids.

BACKGROUND CONTEXT: Intraoperative CT image-guided navigation (IGN) and robotic assistance have been increasingly implemented during spine surgery to improve accuracy in pedicle screw positioning. However, studies have shown that they increase operative time and ionizing radiation exposure, and it remains controversial whether they improve patient outcomes. PURPOSE: Assess use of IGN and robotic assistance in posterior lumbar surgery and their relationship with patient radiation exposure and perioperative outcomes. STUDY DESIGN/SETTING: Retrospective cohort study at single institution. PATIENT SAMPLE: A total of 165 patients undergoing 1- or 2-level posterior spinal fusion, with or without TLIF. OUTCOME MEASURES: Preoperative CT scan utilization and radiation dose, intraoperative radiation dose (fluoroscopy and/or CT) and total-procedure radiation dose (sum of preoperative CT and intraoperative radiation doses), levels fused, operative time, estimated blood loss (EBL), length of stay (LOS), postoperative complications.
METHOD(S): Patients >=18 years old undergoing 1- or 2-level posterior spinal fusion, with or without TLIF, in a 12-month period included. Chart review performed for pre- and intraoperative data on radiation dose and perioperative outcomes. All radiation doses quantified in milli-Grays (mGy). Univariate analysis and multivariate logistic regression analysis for categorical variables and one-way ANOVA for continuous variables utilized, with significance set at p<0.05.
RESULT(S): A total of 165 patients (51.83% F, 59.13+/-13.18yrs, BMI 29.43+/-6.72, Charlson comorbidity index [CCI] 1.20+/-1.56) were assessed: 12 IGN, 62 robotic, 56 open, 35 MIS without IGN/robotics. Lower proportion of women in open and MIS group (66.67% F IGN, 64.52% robotic, 38.18% open, 45.71% MIS, p=0.010). Younger patients in MIS group (63.42 yrs IGN, 61.74 robotic, 60.63 open, 50.63 MIS, p<0.001). MIS group had lowest mean posterior levels fused (1.42 IGN, 1.27 robotic, 1.32 open, 1.06 MIS, p=0.015). Total-procedure radiation (50.21mGy IGN, 59.84 robotic, 22.56 open, 82.02 MIS), total-procedure radiation/level fused (41.88mGy IGN, 51.18 robotic, 18.56 open, 79.41 MIS) and intraop radiation (44.69mGy IGN, 44.85 robotic, 14.81 open, 80.28 MIS) were lowest in the open group and highest in the MIS group compared to IGN and robotic (all p<0.001). A higher proportion of robotic and lower proportion MIS patients had preop CT (25% IGN, 82.26% robotic, 37.5% open, 8.57% MIS, p<0.001). EBL (441.67mL IGN, 380.24 robotic, 355.36 open, 162.14 MIS, p=0.002) and LOS (4.75 days IGN, 3.89 robotic, 3.89 open, 2.83 MIS, p=0.039) were lowest in the MIS group. Highest operative time for IGN patients (303.5 min vs 264.85 robotic, 229.91 open, 213.43 MIS p<0.001). No differences in BMI, CCI, postoperative complications (p=0.313, 0.051, 0.644, respectively).
CONCLUSION(S): IGN and robotic assistance in posterior lumbar fusion were associated with higher intraoperative and total-procedure radiation exposure than open cases without IGN/robotics, but significantly less than MIS without IGN/robotics, without differences in perioperative outcomes. While MIS procedures reported highest radiation exposure to patient, of more concern is that the proportion of total radiation dose applied to surgeon would also be considerably higher in MIS group. FDA DEVICE/DRUG STATUS: Brainlab Airo Mobile Intraoperative CT scanner (Approved for this indication).
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BACKGROUND CONTEXT: Prior adolescent idiopathic scoliosis (AIS) literature has demonstrated that patient satisfaction correlated weakly with individual SRS-22r domains and did not correlate with specific radiographic parameters. PURPOSE: The purpose of this study is to demonstrate the effect of residual deformity on patient satisfaction. We hypothesize that in patients with AIS, residual deformity maybe associated with worse satisfaction. STUDY DESIGN/SETTING: Retrospective analysis of a prospective AIS registry. PATIENT SAMPLE: A total of 1,229 Lenke 1 and 2 AIS patients with available radiographic data and SRS scores at the 2-year follow-up were included. OUTCOME MEASURES: Patient satisfaction using the SRS-22r satisfaction domain, categorized into 2 groups: Complete satisfaction (5/5) and incomplete satisfaction/dissatisfaction (<5).
METHOD(S): A total of 1,229 Lenke 1 and 2 AIS patients with available radiographic data and SRS scores at the 2-year follow-up were included. A score of 5 on the SRS-22r satisfaction domain at 2 years was considered "complete satisfaction," and anything below a score of 5 was considered "incomplete satisfaction/dissatisfaction." Radiographic parameters that were 2 standard deviations below the mean were deemed to have a "residual deformity." Univariate and binary logistic analyses were performed to assess the association of residual deformity with patient satisfaction.
RESULT(S): At the 2-year follow-up, 689 (60%) patients reported complete satisfaction, while 455 (40%) reported incomplete satisfaction/dissatisfaction. Radiographic factors associated with incomplete satisfaction/dissatisfaction were: residual trunk shift (OR 3.32, p=0.001) and residual major curve (OR 1.7, p=0.036). Patients with residual trunk shift and major curve also had worse SRS-22r self-image domain scores at the 2-year follow-up. Residual differences in shoulder height (p=0.534), T1 tilt angle (p=0.062), Apex to CSVL distance (p=0.969), and percent correction of the major curve (p=0.102) did not reach statistical significance for predicting incomplete satisfaction/dissatisfaction.
CONCLUSION(S): Residual curve (>34) and truncal shift (>2.2cm) impact patient satisfaction after surgery for AIS. These factors ought to be taken into account during surgical planning. FDA DEVICE/DRUG STATUS: This abstract does not discuss or include any applicable devices or drugs.
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BACKGROUND CONTEXT: Persistent lumbopelvic malalignment following ASD-corrective surgery may impair quality of life and result in persistent pathologic compensation in the lower extremities. Patient-specific age- and BMI-adjusted alignment targets have been proposed to improve alignment outcomes; however, it is unclear whether reaching these postop targets reduces rates of pelvic nonresponse following surgery. PURPOSE: Assess the relationship between pelvic nonresponse to ASD-corrective surgery and persistent lower-extremity compensation. STUDY DESIGN/SETTING: Single center retrospective review. PATIENT SAMPLE: Fifty-eight ASD patients. OUTCOME MEASURES: Sagittal alignment.
METHOD(S): Included: surgical ASD patients with full-spine X-ray imaging at pre- and early postop follow-up (<1Y). Patients were grouped by postop improvement in PT, per SRS-Schwab Classification: those who did not improve (pelvic nonresponders, PNR), and those that did improve (pelvic responders, PR). Groups were propensity score matched for preop PT, and assessed for differences in demographics, surgical factors, and alignment (sagittal spinal and lower extremity) with means comparison tests. Rates of persistent postop lower extremity compensation (defined as no improvement in lower extremity alignment) were compared between groups. Subanalysis assessed the relationship between reaching postop age- and BMI-specific alignment targets and rates of pelvic nonresponse.
RESULT(S): Following propensity score matching, PNR (N=29) and PR (N=29) patients did not differ in age, sex, BMI or preop sagittal spinal alignment (all p>0.05); however, PNR patients presented with less knee flexion (9degree vs 14degree, p=0.043). Groups did not differ in levels fused (10.8 vs 10.8, p=0.974) or osteotomy (93% vs 92%, p=0.902). Postop, PNR patients had inferior lumbopelvic alignment in PT (30degree vs 17degree), PI-LL (17degree vs 3degree), and greater global malalignment for TPA (27degree vs 15degree, all p<0.001). For PNR patients, these changes in alignment were accompanied by greater compensatory anterior hip extension (53mm vs 31mm, p=0.021). PNR patients also showed greater pre- to postop increases in sacrofemoral angle (2degree vs -5degree), and smaller decreases in hip extension (-24mm vs -64mm), pelvic femoral angle (-1.4degree vs -3.8degree), and global sagittal angle (-3.5degree vs -8degree, all p<0.005), indicating persistent lower extremity compensation. PNR patients had higher rates of persistent postop lower extremity compensation for sacrofemoral angle (68% vs 25%), ankle flexion (64% vs 33%), and pelvic shift (28% vs 4%, all p<0.034). PNR and PR groups did not differ in rates of reaching age- and BMI specific ideal postop alignment for PT, SVA, TPA, or PI-LL (all p>0.05). For patients with severe preop SVA deformity, overcorrection relative to ideal postop PT targets was associated with lower rates of pelvic non-response (under: 12%, match: 18%, over: 71%, p<0.001). Lower rates of nonresponse were observed for patients with severe preop PT deformity overcorrected relative to ideal postop PI-LL (under: 0%, match: 30%, over: 70%, p=0.016).
CONCLUSION(S): Pelvic nonresponders following ASD-corrective surgery had higher rates of persistent compensatory action in the lower extremities. Patients with severe preop PT deformity who were surgically overcorrected with respect to ideal PI-LL had lower rates of postop pelvic nonresponse, indicating that for severely malalignmed patients, existing alignment targets may need to be adjusted to optimize alignment outcomes. FDA DEVICE/DRUG STATUS: This abstract does not discuss or include any applicable devices or drugs.
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BACKGROUND CONTEXT: Antifibrinolytic agents are used during ASD surgery to minimize blood loss and transfusion requirements. Tranexamic acid (TXA) reduces the risk of blood loss and transfusion after ASD surgery, but there persists concern for prothrombotic effects, myocardial infarction, stroke, and postoperative neurologic events including seizures. PURPOSE: To investigate perioperative blood loss and transfusion after TXA for ASD surgery. STUDY DESIGN/SETTING: Retrospective review of prospectively collected single center database. PATIENT SAMPLE: 469 patients who received TXA, and 354 patients who did not receive TXA. OUTCOME MEASURES: Perioperative blood loss and blood product transfusion rate, and complications.
METHOD(S): Using a single-institution multi-surgeon database, we performed a retrospective review of patients undergoing ASD surgery from 2011-2018. We identified 469 patients who received TXA, and 354 patients who did not receive TXA. We investigated perioperative blood loss and blood product transfusion rate, and complications occurring after surgery.
RESULT(S): There was no significant difference in age, BMI, or frailty between the TXA (age: 45 +/- 23, BMI: 25 +/- 6) and non-TXA group (age: 47 +/- 24, BMI: 26 +/- 7). The prevalence of coronary artery disease, chronic kidney disease, and history of pulmonary embolism was higher in the non-TXA group, presumably due to surgeon preoperative screening, with no difference in other medical comorbidities. There were more revision surgeries and pelvic fixation procedures in the TXA group, with no other differences in surgical complexity. The group that received TXA had significantly lower EBL (1693 +/- 1343 mL vs 2009 +/- 1892 mL, p=0.019), and were transfused less platelets intraoperatively (.07 +/-.3 U vs 0.25 +/- 0.86 U, p=0.012). There was no difference in rates of perioperative pRBC transfusion between the groups. The most common complications in both groups were ileus and urinary retention. There was no difference in rate of thrombotic, cardiac, or renal complications, or seizures between the two groups. There was no significant difference in 90-day complication, readmission, or revision rates.
CONCLUSION(S): Among patients undergoing ASD surgery, TXA was associated with a lower estimated blood loss, without a higher risk for any morbid event. To our knowledge, this is the largest study to date to evaluate the safety of TXA for ASD surgery. FDA DEVICE/DRUG STATUS: Unavailable from authors at time of publication.
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BACKGROUND CONTEXT: Lateral interbody fusion (LLIF) is often performed with biologic adjuvants to promote fusion. Commercially available bone allograft containing allogeneic stem cells (ASC) and bone morphogenetic protein-2 (BMP) are designed to promote fusion while avoiding the morbidity of iliac crest autograft; however, no study to date has directly compared the two in LLIF. The ASC studied is Osteocel Pro (NuVasive, Inc). PURPOSE: This non-industry funded study compares fusion rate, complications, and costs between LLIF with BMP and ASC. STUDY DESIGN/SETTING: Single center retrospective comparative study. PATIENT SAMPLE: Patients with 1-3 lumbar levels treated with LLIF. OUTCOME MEASURES: Outcomes measures are fusion at 1 year postoperative, complication rates, length of stay, and costs.
METHOD(S): A retrospective chart review was conducted to identify patients treated with LLIF and ASC or BMP from February 2012 through September 2017. Patients were included who had from 1-3 lumbar levels treated with LLIF and at least 1 year of radiographic follow up. Interbody fusion was assessed on lumbar X-ray images using a validated scale.
RESULT(S): A total of 94 patients were included representing 162 levels fused. Of these, 74 patients and 133 levels were treated with BMP; 20 patients and 29 levels were treated with ASC. Comparing patients treated with BMP or ASC, there were no differences in age [61.6 vs 60.4, p=0.7], BMI [29.8 vs 28.3, p=0.3], gender [60.8% vs 55.0% female], smoking status [12.2% vs 10.0%, p=1], diabetes [28.4% vs 15.0%, p=0.2], Charleston Comorbidity Index [4.3 vs 3.5, p=0.2], revision status [47.3% vs 45.0%, p=0.9], intraoperative complications [4.1% vs 5.0%, p=1], postoperative complications [37.8% vs 30.0%, p=0.5], or blood loss [881 vs 528ml, p=0.2]. More levels were fused in the BMP group (1.8 vs 1.45, p=0.04) and the BMP group tended toward a longer length of stay [4.8 vs 3.8 days, p=0.06]. There was a nonsignificant trend toward a higher fusion rate with BMP vs ASC[98.5% vs 93.1%, p=0.1]. The average amount of rhBMP used per level was 2.0 cc compared to 5.9 cc of ASC. There was no difference in the cost of the BMP per level compared with ASC [4.45% vs 4.80%, p=0.33], but the BMP group tended toward a higher cost of total care [103.5% vs 87.6%, p=0.1].
CONCLUSION(S): ASC and BMP are both acceptable adjuvants in LLIF that demonstrate comparable fusion rates at 1 year with comparable cost in the setting of similar groups of patients. The radiographic fusion rate seen in our study compares to previous reports in the literature using ASC. Cost considerations are becoming ever more cogent in spine surgery; the results of this study can inform decision making regarding which biologic adjuvant to use in lumbar interbody fusion. FDA DEVICE/DRUG STATUS: Osteocel (Approved for this indication), rhBMP (Infuse) (Not approved for this indication)
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BACKGROUND CONTEXT: Lumbar herniated nucleus pulposus (HNP) is a common spinal pathology often treated by microscopic lumbar discectomy (MLD), though prior reports have not demonstrated which preoperative MRI factors may contribute to significant clinical improvement after MLD. PURPOSE: To analyze the MRI characteristics in patients with HNP that predict meaningful clinical improvement in Health Related Quality of Life scores (HRQL) after MLD. STUDY DESIGN/SETTING: Retrospective clinical and radiological study of patients undergoing MLD for HNP at a single institution over a two year period of time. PATIENT SAMPLE: Eighty-eight patients receiving MLD treatment for HNP. OUTCOME MEASURES: Cephalocaudal canal migration; canal & HNP anterior-posterior (AP) lengths and ratio; canal & HNP axial areas and ratio; hemi-canal & hemi-HNP axial areas and ratio; disc appearance (black, grey or mixed), baseline (BL) and 3-month (3M) postoperative HRQL scores.
METHOD(S): Patients >18 years old who received MLD for HNP with BL and 3M HRQL scores of PROMIS (Physical Function, Pain Interference, and Pain Intensity), ODI, VAS Back, and VAS Leg scores were included. HNP and spinal canal measurements of cephalocaudal migration, AP length, area, hemi-area, and disc appearance were performed using T2 axial and sagittal MRI. HNP measurements were divided by corresponding canal measurements to calculate AP, Area, and Hemi-Area ratios. Using known minimal clinically importance differences (MCID) for each DELTAHRQoL score, patients were separated into two groups based on whether they reached MCID (+) or did not reach MCID (-). The MCID for Pain Intensity was calculated using a decision tree. A linear regression illustrated correlations between PROMIS vs ODI and VAS Back/Leg scores. Independent t-tests and chi-square tests were utilized to investigate significant differences in HNP measurements between the (+) and (-) MCID groups.
RESULT(S): Eighty-eight MLD patients were included (age=44.6+/-14.9, 38.6% female). Pain Interference and pain intensity were strongly correlated with ODI and VAS Back/Leg (R>=.505), and physical function was significantly correlated with ODI and VAS Back/Leg (R=-.349) (all p<.01). The strongest MRI predictors of meeting HRQL MCID were grey disc appearance, HNP area (>116.6 mm²), hemi-HNP Area (>84.6 mm²), and Hemi-Area Ratio (>51.8%); (+) patients were 2.7 times more likely to have a grey HNP than (-) patients in 5 out of 6 HRQL score comparisons (p<.025). Also, (+) patients had larger HNP areas than (-) patients had in 5 out of 6 HRQoL score comparisons (116.6 mm² +/- 46.4 vs 90.0 mm² +/- 43.2, p<.04), and had larger hemi-HNP areas than (-) patients had in 4 out of 6 HRQL score comparisons (84.6 mm² +/- 38.8 vs 66.3 mm² +/- 29.7, p<.04). (+) patients had a greater hemi-area ratio than (-) patients had in 4 out of 6 HRQL score comparisons (51.8% +/- 14.7 vs 43.9% +/- 14.9, p<.05).
CONCLUSION(S): Patients who met MCID after MLD had larger HNP areas by 26.6 mm² and larger hemi-HNP areas by 18.3 mm² than those who did not meet MCID. These patients were also 2.7x more likely to have a grey HNP compared to patients who did not meet MCID. When accounting for HNP area relative to canal area, patients who met MCID had a 7.9% greater Hemi-HNP canal occupation than patients who did not meet MCID. The results of this study suggest that preoperative MRI parameters can be useful in predicting patient reported improvement after MLD. FDA DEVICE/DRUG STATUS: This abstract does not discuss or include any applicable devices or drugs.
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