Faculty Bibliography

BACKGROUND CONTEXT: The thoracolumbar junction poses increased risk for high stress on upper lumbar discs when not adequately fused. However, controversy persists. This study evaluates outcomes of upper instrumented vertebrae (UIV) selection in the thoracic versus the upper lumbar spine when fusing to the sacrum. PURPOSE: To compare revision rates for thoracolumbar fusions to the sacrum and pelvis at 1- and 2-year follow-up, stratified by UIV selection. STUDY DESIGN/SETTING: Retrospective cohort study at a single institution. PATIENT SAMPLE: A total of 968 patients who had thoracolumbar fusion surgery between 2012-2018 with at least one year of postoperative follow-up. OUTCOME MEASURES: Reoperation rates from 1 and 2 years after revision surgery, reoperation diagnoses, body mass index (BMI), gender, Charleston Comorbidity Index (CCI), perioperative complications, ASA grade (ASA), operative time (OT), and blood loss (EBL).
METHOD(S): A retrospective review of patients undergoing revision spinal fusion with lower instrumented vertebra of S1 or pelvis between 2012-2018 at a single institution was performed. Patients with less than 1 year of follow-up after their index procedure were excluded from the analysis. Patients were categorized based on UIV into 6 groups: T9-T11, L1, L2, L3, L4, and L5. Demographic and operative data were collected and compared between the different UIV groups in each cohort using chi-squared and ANOVA tests. Revision rates at 1- and 2-year follow-up and the reasons for revision were compared between groups.
RESULT(S): There were 168 revision spinal fusions that reached 1-year follow-up, with 54 having UIV at T9-T11, 2 fusions L1 to sacrum, 26 fusions L2 to sacrum, 25 fusions L3 to sacrum, 36 fusions L4 to sacrum, 23 fusions L5 to sacrum. There was significant difference in patient age, with oldest in the L1 group (65.5+/-3.5) and youngest in the L5 group (51+/-15.4 p<0.001). There was significant difference in gender as both cases in L2 was female and L5 fusions only had 39.1% females (p = 0.006). There were no differences in BMI, CCI, and ASA. EBL (1891.6mL+/-1226.9mL p <0.001) and length of stay (7.7+/-3.0 p <0.001) was highest in the T9-11 UIV group. Operative time was highest in the L1 (464.5+/-174.7 p<0.001) UIV group. Levels added on top of prior fusion were calculated by subtracting UIV of index fusion to past UIV. Adding on 2 levels had a 1-year revision rate of 14.3% (p = 0.032), while adding on 1 level had a 0% 1-year revision rate. Adding on 4 levels had a revision rate of 12.5%, and adding on 7 levels had a 50% 1-year revision rate. At 2 years, adding on 1 level had revision rate of 25% and adding on 2 levels had a revision rate of 20% (p = 0.769). There is no statistically significant difference in perioperative complication rates between UIV groups (p = 0.114). The reoperation rate at 1 year for all levels was 9% and highest in UIV at L1 (50%, p=0.06). At 2-year follow-up, the reoperation rate for the total cohort was 32.34% with the highest revision rate for fusion from L2 to sacrum (53.85%) followed by (T9-T11 sacrum fusion 42.31%, L4 to sacrum31.71%, L3 to sacrum 30%, L5 to sacrum 25.04%, L1 to sacrum 25%, p=0.195). Grouping the UIV into lower thoracic (T9-T11), upper lumbar (L2-L3), and lower lumbar (L4-L5) showed similar revision rates at one year (p=0.697). At two years, lower thoracic group had a revision rate of 40% versus, 23.3% in the upper lumbar group (p =0.399).
CONCLUSION(S): There is no statistically significant difference in reoperation rates for revision thoracolumbar fusions to the sacrum/pelvis associated with different UIV selection. FDA DEVICE/DRUG STATUS: This abstract does not discuss or include any applicable devices or drugs.
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BACKGROUND CONTEXT: Frailty is a baseline measure of disability that transcends age alone and has been determined a strong predictor of outcomes following adult spinal deformity (ASD) surgery. This postop impact calls for investigation of unique adjustment of Global Alignment and Proportion (GAP) scores accounting for frailty. This adjustment in spinal proportion may help surgical planning for individualized, optimal postop outcomes. PURPOSE: Modify the GAP score with frailty to optimize outcomes in surgical ASD patients. STUDY DESIGN/SETTING: Retrospective review of a single-surgeon comprehensive ASD database PATIENT SAMPLE: A total of 140 ASD patients OUTCOME MEASURES: Frailty-adjusted GAP scores; Health Related Quality of Life scores (HRQLs): ODI, SRS-22 METHODS: Surgical ASD patients (SVA>=5cm, PT>=25degree, or TK >=60degree, >3 levels fused) >=18 years old with available baseline (BL) radiographic data were isolated in the single-center Comprehensive Spine Quality Database (Quality). Patients were dichotomized by the ASD frailty index, F (Not Frail, Frail). Linear regression analysis established radiographic equations for frailty-adjusted GAP Scores at baseline and 2-years involving relative pelvic version, relative lumbar lordosis, lordosis distribution index, relative spinopelvic alignment, and an age factor to formulate a sagittal plane score. Patients were restratified into frailty-adjusted proportionality groups: Proportional (<5.8), Moderately Disproportional (MD) (5.8-7), Severely Disproportional (SD) (>7). Frailty-adjusted GAP proportionality at 2-years were compared to adjusted-BL to determine whether patients improved, deteriorated or remained the same in their spine proportion.
RESULT(S): A total of 140 patients were included (55.5+/-16.4 yrs, 77.5% female, 25.2+/-4.7 kg/m2). BL frailty: 32.8% not frail, 67.2% frail. Primary analyses demonstrated correlation between BL frailty score and BL and 2-year GAP scores(P<0.001). Linear regression analysis(p<0.001) developed a frailty-adjusted GAP threshold equation: 4.4 + 0.93*(frailty score). Adjusted-baseline scores were taken and re-stratified based distribution and placed 26.4% of patients in Proportional, 26.6% MD, and 44% SD. BL adjusted GAP scores by frailty group: 5.3 Not Frail, 7.5 Frail; p<0.001. At 2-years, GAP scores were grouped into the frailty-adjusted proportionality groups: 66.2% Proportional, 10.8% MD, and 23.1% SD. Patients who were 2-year MD/SD underwent significantly more reoperations (>33.5%) compared to Proportional (12.8%), p=0.015. SD 2-year patients developed increased PJK at the 1-year mark (40%, Proportional: 13.9%, MD:7.1%, p=0.003), as well as had worse 2-year ODI and SRS-22 satisfaction scores(p<0.050). 47.5% improved in GAP (63.4% of frail patients), 12.3% deteriorated, and 40.2% remained in the same proportionality group at 2-year follow up.
CONCLUSION(S): Significant associations exist between frailty and spinal proportion. By adjusting the GAP proportionality groups accounting for baseline frailty contributed to improved outcomes and minimized reoperations. The adjusted GAP groups appeal for less rigorous spine proportion goals in severely frail patients. FDA DEVICE/DRUG STATUS: This abstract does not discuss or include any applicable devices or drugs.
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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.
METHOD(S): Patients undergoing 1-2 level TLIF or 1-3 level ALIF were included. Analysis of variance (ANOVA) and chi2test were used to analyze differences in outcomes with significance set at p<0.05. Post hoc Tukey (PHT) and Bonferroni (PHB) analysis were conducted when ANOVA or chi2 showed significance. RD was propensity matched for BMI. TLIFs underwent PSM for levels fused.
RESULT(S): 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 <0.001 and 5.38+/-1.66 days p<0.001); EBL most in FG (482.43+/-530.79mL p=0.006). After PSM for BMI, there was no significant difference in RD. RG TLIF registration failed in 2.8% of cases. There were significantly more intraop (11.1%, p=0.008), and postop (45.8%; p<0.001) complications in the RG cohort, which showed high durotomy rates (6.9%; p=0.05) and instrumentation failure rates approaching significance (3.5%; p=0.058). The NAV group had the highest rate of SSI (2.5%; p = 0.045). Among the ALIF cohorts: RD, EBL, and LOS were similar; OT was longest in FG (395.7+/-113.7 p=0.001). There were significantly more intra- and postop complications in RG group (26.3%, p<0.001; 30%, p<0.001) and 13.8% of RG failed registration. Instrumentation failure was highest in FG (4.0% p=0.676), along with return to OR for instrumentation (8%, p = 0.183). Other periop complications and returns to OR were not significantly different.
CONCLUSION(S): 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.
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BACKGROUND CONTEXT: Recombinant human bone morphogenetic protein 2 (rhBMP-2) is a popular biologic product used in transforaminal lumbar interbody fusion (TLIF) surgeries to promote fusion and avoid the morbidity associated with iliac crest autograft. However, use of rhBMP-2 and its effect on pseudarthrosis rates in TLIFs remains unknown. PURPOSE: To assess the rates of pseudarthrosis in open and MIS TLIF patients, with and without concurrent rhBMP-2 use. STUDY DESIGN/SETTING: Retrospective cohort study at a single academic institution. PATIENT SAMPLE: Included: 317 single level TLIF patients. Consisting of 157 open TLIF (OTLIF), 115 bilateral Wiltse MIS TLIF (WTLIF), and 45 hybrid midline MIS with percutaneous pedicle or cortical screws (MTLIF). OUTCOME MEASURES: Clinical characteristics, perioperative and postoperative outcomes, surgical procedure, rates of pseudarthrosis diagnosis, and revision for pseudarthrosis.
METHOD(S): Patients >=18 years old undergoing 1-level TLIF with minimum 1-year of clinical and radiographic follow up were included. Pseudarthrosis was determined using both radiographic and clinical evaluations. Differences between groups were assessed by ANOVA and chi squared analyses. Demographic and perioperative characteristics were analyzed by multivariate logistic regression.
RESULT(S): The cohort included 317 patients (mean age 59.68+/-13.29, F 52.7%). There was no significant difference in gender, BMI, or smoking status among groups (all p>.05). WTLIF had the lowest EBL (ml) (192.16+/-177.11mL vs 302.73+/-246.51 vs 363.85+/-370.49, respectively p=<0.001) and LOS (days) (2.88+/-1.76 vs 4.16+/-3.94 vs 4.03+/-1.97, respectively p=<0.001) compared to MTLIF and OTLIF. Further, MTLIF had the highest fluoroscopic dose (mGy) compared to WTLIF and OTLIF (52.85+/-40.49 vs 52.80+/-52.77 vs 15.21 +/- 24.53, respectively p=<0.001). MTLIF was also associated with the lowest BMP use compared to OTLIF and MTLIF (13.3% vs 23.6% vs 67.8%, respectively p=<.001). At minimum 1-year follow-up, there was no significant difference between the three different approaches with regards to pseudarthrosis rates (WTLIF 6.1%, MTLIF 8.9%, OTLIF 3.2%, p=0.249) or returns to the OR for pseudarthrosis (WTLIF 3.5%, MTLIF 6.7%, OTLIF 3.2%, p=0.546). Pseudarthrosis rates in patients treated with BMP was 5% (p = 0.881) for the cohort. There was no difference in reoperation for pseudarthrosis between patients who received BMP (2.5%) versus those who did not receive BMP (4.6%, P = 0.338). Multivariate Logistic regression analysis demonstrated no reduction in pseudarthosis related to BMP use (Odds Ratio 1.07 [CI 95% 0.228-5.04], p=0.929). Current or past smoking did not have an effect on use of BMP (p = 0.369) or significantly increase the rate of pseudarthrosis (p = 0.214), regardless of BMP use.
CONCLUSION(S): MP use did not reduce the rate of pseudarthrosis or the number of reoperations for pseudarthrosis in this cohort. No difference in pseudarthrosis rates between the three TLIF approaches was noted. FDA DEVICE/DRUG STATUS: This abstract does not discuss or include any applicable devices or drugs.
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BACKGROUND CONTEXT: Frailty is an increasingly recognized characteristic that has been validated across many studies as influencing operative risk. Utilization of frailty indices can allow for its identification of which spine patients may be too high risk for surgical intervention. This may be especially useful when it comes to surgeries that are minimally invasive and are supposed to have decrease perioperative outcomes. PURPOSE: Identify MIS techniques effects in postoperative outcomes in TLIF patients. STUDY DESIGN/SETTING: Retrospective review of a prospective database. PATIENT SAMPLE: TLIF spine patients. OUTCOME MEASURES: Complications, length of stay (LOS), estimated blood loss (EBL).
METHOD(S): Pts that underwent a lumbar spine procedure in a single-center Comprehensive Spine Quality Database. Pts were stratified based on procedural approach (Open [OP] and Minimally invasive Surgery [MIS]). Frailty was then calculated for each resultant group by using 30 variables with a validated method. Based on these scores, pts were categorized no frailty [NF]: <0.09, frail [F]: 0.09-0.18, and severe frailty [SF] >0.18. Groups were then controlled for surgical invasiveness. Chi-squared tests identified the relationship between complications and length of stay among various frailty states given surgical approach (OP vs MIS). These patients were propensity score matched for levels fused. Hospital acquired complications (HACs) were identified based on frailty groups through the use of chi-squared and t-tests for other surgical factors. A logistic regression analysis identified the association between frailty status and surgical, regarding postoperative (postop) outcomes.
RESULT(S): A total of 1,300 TLIF spine patients were isolated (59yrs, 29.3kg/m2). After PSM for levels fused, there were 338 pts for both MIS and OP. MIS pts were older (56.1 vs 53.3; p<0.05) than Op pts and had similar BMI's (29.1 vs 29.7; respectively). However, OP received more posterior approaches and less anterior approaches than MIS pts (p<0.05). By surgical factors: MIS and OP patients had similar LOS (3 vs 2.9days) and EBL (282.8 vs 251.5cc) but differed by Op time (195.7 vs 247.1; p<0.05) respectively. Further breakdown by frailty displayed statistical significance between MIS and OP patients with MIS pts having more F (16% vs 12%) and SF pts (4.3% vs 1.9%) than OP (all p<0.05). FMIS patients had lower postop neurologic complications as compared to FOP pts (4.63% vs 14.8%). However, SFMIS patiens had more post-operative complications than SFOP pts (55.2% vs 23.1%) and increased a pt's likelihood of being SFMIS by 5.4x's (all p<0.05).
CONCLUSION(S): This study displays that when frailty status is taken into account, TLIF MIS patients benefit from this procedure type when analyzed against neurologic complications. However, these patients were seen to suffer more from postop complications but did not differ on any other specific complications or surgical variables. FDA DEVICE/DRUG STATUS: This abstract does not discuss or include any applicable devices or drugs.
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BACKGROUND CONTEXT: Expandable cages (EXP) are more frequently utilized in Transforaminal Lumbar Interbody Fusions (TLIF). Designed to reduce complications related to neurological retraction, enable better lordosis restoration, and improve ease of insertion, particularly in the advent of minimally invasive techniques they are exponentially more expensive than the non-expandable (NE) alternate. PURPOSE: To investigate the value of expandable cages given the significantly higher cost. STUDY DESIGN/SETTING: Retrospective review at a single institution. PATIENT SAMPLE: A total of 257 TLIFs between 2012 and 2018 were included. OUTCOME MEASURES: Clinical characteristics, perioperative and neurologic complication rates and radiographic measures.
METHOD(S): Patients >= 18 years of age who underwent single-level TLIF with minimum 1-year follow-up were included. Outcome measures: clinical characteristics, perioperative complications and neurologic complications. Radiographic analysis included change in pelvic incidence-lumbar lordosis (PI-LL), segmental lumbar lordosis (LL), and disc height restoration. Subsidence was radiographically assessed at 1-year follow-up from intraoperative imaging for breaching of the vertebral endplates, measured from the cage endplate to vertebral endplate and defined as a >2mm. Statistical analysis included independent t-tests and chi-square analysis with significance set at p<0.05.
RESULT(S): A total of 257 TLIFs between 2012 and 2018 were included, with 155 NE (53.5% female, mean age 59.46+/-14.07, mean BMI 28.69+/-5.39) and 102 EXP (49% female, mean age 57.78+/-11.76, mean BMI 28.72+/-6.01) with no significant differences in demographics. There were significantly more MIS TLIF cases and BMP use in the EXP group (88.2% MIS, p<0.001 and 59.8% BMP, p<0.001). When controlling for proportion of MIS cases, EXP had a lower operative time and estimated blood loss respectively (215.74+/-59.53 min, p=0.015; 194.72 +/- 187.19 mL, p=0.028). There were no other significant differences in clinical outcomes due to the instrumentation, though there were limited numbers (N=132: 90 EXP vs 42 NE). There were no significant differences between the EXP and NE groups in postoperative rates of radiculitis (14.4% vs 9.5%, p=0.462), and neuropraxia (7.8% vs 7.1%, p=0.750). Radiographic analyses demonstrated no significant differences with respect to change in baseline to 1-year follow-up between groups. No significant difference in post-operative subsidence was observed between the EXP and NE from intraoperative to 1-year follow-up (28.9% vs 28.6%, p=0.970).
CONCLUSION(S): Once technique was controlled for, TLIFs utilizing EXP do not have significantly different neurologic or radiographic outcomes compared to NE. These results question the value of EXP given the higher cost. The findings require further direct comparison in the MIS population because the benefit on outcomes compared to the alternate remains controversial due to the bias towards increased use in MIS procedures. FDA DEVICE/DRUG STATUS: This abstract does not discuss or include any applicable devices or drugs.
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BACKGROUND CONTEXT: Hospital acquired conditions (HACs) were established in the Affordable Care Act, and are defined as reasonably preventable complications that are nonreimbursable. In high risk patient populations for HACs, such as frail surgical spine patients, preoperative evaluation should consider modifiable factors. PURPOSE: To identify if optimizing the modifiable factors in the frailty index reduce the risk of developing HACs in population of surgical spine patients. STUDY DESIGN/SETTING: Retrospective cohort study. PATIENT SAMPLE: This study included 196,523 elective spine surgery patients in the American College of Surgeons National Surgical Quality Improvement Program (ACS-NSQIP). OUTCOME MEASURES: Modifiable patient frailty factors: hypertension and diabetes mellitus; rates of HACs, superficial or deep surgical site infection (SSI), deep venous thromboembolism (VTE) and urinary tract infection (UTI), across frailty scores.
METHOD(S): Patients >18 years who underwent elective spine surgery were identified in ACS-NSQIP database from 2005-2016. HACs identified: SSI, VTE, and UTI. Patient frailty was assessed utilizing the modified NSQIP 5-factor frailty index. The modified frailty score (mFI-5) is assessed on a scale between 0 and 1 (no frailty [NF] <0.3, mild frailty [MF] 0.3-0.5, severe frailty [SF] >0.5). Descriptive analysis quantified rates of patient characteristics, operative details, and HAC prevalence. Stepwise linear regression models determined significant predictors of baseline frailty using controllable patient factors. HACs were compared between 'optimized' and 'non-optimized' frailty status in the cohort. Level of significance was set to P<0.05.
RESULT(S): A total of 196,523 patients (57+/-14.2 years, 30.4 kg/m², 48%F) met inclusion criteria. Overall, 5,720 (2.9%) of patients developed an HAC, the most common was an SSI (1.3%), followed by UTI (1.1%). When stratified by the mFI-5 frailty severity groups at baseline, 83.6% of patients were categorized NF, 15.1% MF and 1.3% SF. Within the frailty severity groups, prevalence of overall HACs increased significantly (NF: 2.64%, MF: 4.17%, 5.93%, p<0.001). Rates of all individual postoperative HACs assessed also increased with greater baseline frailty severity: SSI (NF: 1.14%, MF: 1.93%, SF: 2.39%, p<0.001), UTI (NF: 0.91%, MF: 1.66%, SF: 2.85%, p<0.001), VTE (NF: 0.68%, MF: 0.80%, SF: 1.16%, p=0.002). Stepwise linear regression models determined that diabetes mellitus (beta = 0.493) and hypertension (beta = 0.679) were the most significant predictors for increased baseline frailty by way of the mFI-5 NSQIP index (Final model: R2= 0.897). Of total patients, 47.2% had the optimal modifiable frailty factors (no history of diabetes or hypertension). The optimal frailty patients had significantly less overall incidence of SSI (2.03% vs 2.5%, p<0.001), UTI (0.65% vs 1.4%, p<0.001), DVT (0.56% vs 0.84%, p<0.001), and any overall HAC (2.18% vs 3.56%, p<0.001).
CONCLUSION(S): Stepwise linear regression models determined that hypertension and diabetes account for 89.7% of variance in baseline mFI-5 score. Patients with these optimal controllable factors had reduced incidence of all hospital acquired conditions. In order to optimize hospital resources and treatment outcomes, physicians and patients should be aware of the modifiable factors that contribute to a patient's frailty that can ultimately impact acquiring HACs. FDA DEVICE/DRUG STATUS: This abstract does not discuss or include any applicable devices or drugs.
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Metabolic syndrome is a clustering of clinical findings defined in the literature including hypertension, high glucose, abdominal obesity, high triglyceride, and low high-density lipoprotein cholesterol levels. The purpose of this study was to assess perioperative outcomes in patients undergoing spine fusion surgery with (MetS) and without (no-MetS) a history of metabolic syndrome. Included: Patients ≥18 yrs old undergoing spine fusion procedures diagnosed with MetS components with BL and 1-year follow-up were isolated in a single-center database. Patients in the two groups were propensity score matched for levels fused. 250 spine fusion patients (58 yrs, 52.2%F, 39.0 kg/m²) with an average CCI of 1.92 were analyzed. 125 patients were classified with MetS (60.2 yrs, 52%F, CCI: 3.2). MetS patients were significantly older (p = 0.012). MetS patients underwent significantly more open (Met-S: 78.4% vs No-MetS: 45.6%, p < 0.001) and posterior approached procedures (Met-S: 60.8% vs No-MetS: 47.2%, p = 0.031). Mean operative time: 272.4 ± 150 min (MetS: 288.1 min vs. no-MetS: 259.7; p = 0.089). Average length of stay: 4.6 days (MetS: 5.27 vs no-MetS: 3.95; p = 0.095). MetS patients had more post-operative complications (29.6% vs. 18.4%; p = 0.038), specifically neuro (6.4% vs 2.4%), pulmonary (4% vs. 1.6%), and urinary (4.8% vs 2.4%) complications. Binary logistic regression analyses found that MetS was an independent risk factor for post-operative complications (OR: 1.865 [1.030-3.375], p = 0.040). With longer surgeries and greater open-exposure types, MetS patients were at greater risk for complications, despite controlling for total number of levels fused. Surgeons should be aware of the increased threat to spine surgery patients with metabolic syndrome in order to optimize surgical decision-making.

In the current value-based healthcare climate where spine surgery is shifting to the ambulatory setting, factors influencing postop length of stay (LOS) are important to surgeons and hospital administrators. Pre-op patient factors including diagnosis of radiculopathy and myelopathy have yet to be investigated in this context. Operative pts ≥ 18Y with primary diagnoses of cervical myelopathy (M), radiculopathy (R), or myeloradiculopathy (MR) were included and propensity score matched by invasiveness score (Mirza et al.). Top-quartile LOS was defined as extended. M&R patients were compared using Chi² & independent t-tests. Univariate tests assessed differences in preop patient and surgical data in M&R pts and extended/non-extended LOS. Stepwise regression analysis explored factors predictive of LOS. 718 operative pts (54.5 yrs, 41.1%F, 29.1 kg/m², mean CCI 1.11) included (177 M, 383 R, and 158 MR). After PSM, 345 patients remained (115 in each diagnosis). 102 patients had E-LOS (Avg: 5.96 days), 41 M patients (mean 7.1 days), 28 R (5.9 days), and 33 MR (4.6 days). Regression showed predictors of E-LOS in R pts (R²â€¯= 0.532, p = 0.043): TS-CL, combined and posterior approach, LIV, UIV, op time, Lactated Ringer's, postoperative complications. Predictors of E-LOS in M pts (R²â€¯= 0.230, p < 0.001): age, CCI, combined and posterior approach, levels fused, UIV, EBL, neuro and any postop complications. Predictors of E-LOS in MR patients (R²â€¯= 0.152, p < 0.001): age, kyphosis, combined approach, UIV, LIV, levels fused, EBL and op time. Independent of invasiveness, patients with a primary diagnosis of myelopathy, though older aged and higher comorbidity profile, had consistently longer overall postop LOS when compared to radiculopathy or myeloradiculopathy patients.

BACKGROUND CONTEXT: Numerous advances have been made in the field of spine fusion, such as minimally invasive (MIS) or robotic assisted spine surgery. However, it is unknown how these advances have impacted the cost of care. PURPOSE: Compare the economic outcomes of lumbar spine fusion between open, MIS and robotic assisted surgery patients. STUDY DESIGN/SETTING: Retrospective review of a single center spine surgery database. PATIENT SAMPLE: A total of 360 propensity matched patients. OUTCOME MEASURES: Costs, EuroQol-5D (EQ5D), Cost per quality adjusted life years (QALY).
METHOD(S): Inclusion criteria: surgical patients >18 years undergoing lumbar fusion surgery. Patients were categorized into 3 groups based on procedure type: open, MIS or robotic. Open patients undergoing poster spinal fusion were considered as the control group. MIS patients included those undergoing transforaminal or lateral lumbar interbody fusion with percutaneous screws. Robotic patients were those undergoing robot assisted fusion. Propensity score matching was performed between all groups for the number of levels fused. Costs were calculated using the PearlDiver database, which reflects both private insurance and Medicare reimbursement claims for ICD-9 codes. For robot cases, costs were reflective of operational fees and initial purchase cost. Complications and comorbidities (CC) and major complications and comorbidities (MCC) were assessed according to CMS.gov manual definitions. QALYs and cost per QALY were calculated using a 3% discount rate to account for residual decline to life expectancy (78.7 years). Costs per QALY were calculated for both 1 year and life expectancy, assuming no loss of benefit.
RESULT(S): A total of 360 propensity matched patients (120 open, 120 MIS, 120 robot) met inclusion. Descriptive statistics for the cohort were: age 58.8+/-13.5, 50% women, BMI 29.4+/-6.3, op time 294.4+/-119.0, LOS 4.56+/-3.31 days, EBL 515.9+/-670.0 cc, and 2.3+/-2.2 average levels fused. Rates of postop complications were significantly higher in robotic cases versus open and MIS (43% vs. 21% and 22% for open and MIS, p<0.05). However, revision rates were comparable between all groups (3% open, 3% MIS, 5% robotic, p>0.05). After factoring in complications, revisions, and purchasing and operating fees, the costs of robotic cases was significantly higher than both open and MIS surgery ($60,047.01 vs. $42,538.98 open and $41,471.21 MIS). In a sub analysis of 42 patients with BL and 1Y EQ5D data, the cost per QALY at 1Y for open, MIS, and robot assisted cases was $296,624.48, $115,911.69, and $592,734.30. If utility gained was sustained to life expectancy, the cost per QALY was $14,905.75, $5,824.71, $29,785.64 for open, MIS, and robot assisted cases.
CONCLUSION(S): Numerous advances have been made in the field of spine surgery, however, there has been limited discussion of the effect these advances have on economic outcomes. When matched for levels fused, robot assisted surgery patients had significantly higher rates of complications and 30% higher costs of surgery compared to minimally invasive and open spine surgery patients. While 1 year economic outcomes weren't optimal for robotic surgery cases, the projected costs per quality adjusted life years at life expectancy were well below established acceptable thresholds. FDA DEVICE/DRUG STATUS: This abstract does not discuss or include any applicable devices or drugs.
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