Faculty Bibliography

BACKGROUND CONTEXT: Age-adjusted alignment targets for adult spinal deformity (ASD) patients have the potential to reduce the incidence of PJK while ensuring optimal HRQL. Previous studies demonstrated the interplay between lumbar lordosis (LL) and thoracic kyphosis (TK) and their relationship with pelvic morphology as measured by the plevic incidence (PI). In clinical practice, reaching this ideal alignment remains challenging as the relationship between lordosis and kyphosis is not clearly elucidated. PURPOSE: This study aimed at developing a pragmatic formula on how much lumbar lordosis is needed based on the patient age, PI and exiting thoracic kyphosis. STUDY DESIGN/SETTING: Multicenter retrospective review of a prospective database. PATIENT SAMPLE: A total of 347 adult spinal deformity patients reaching age-adjusted alignment at 1-year post surgery. OUTCOME MEASURES: Sagittal alignment and internal validation of predictive formula.
METHOD(S): Surgical ASD patients reaching an age-adjusted ideal alignment at one year were identified. Multilinear regressions analysis was used to identify the relationship between regional curvatures (LL &TK) permitting to reach a given global alignment (TPA) based on pelvic incidence.
RESULT(S): The 347 patients included (60 years old, 72% female, BMI 29+/-6.2) had a significant improvement in all sagittal parameters from pre-op to 1Y (p<0.001 except PI). Multilinear regression predicting L1-S1 based on TK, TPA and PI demonstrated excellent results (R2=0.85). Similar results were found when regressions were conducted for each TPA percentile group (R2 ranging from 0.83 to 0.87). Simplification of the coefficients of prediction led to the following equation: LL = PI + 0.3

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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BACKGROUND CONTEXT: Adult spinal deformity (ASD) correction involves complex, invasive procedures. However, it is unknown how metabolic syndrome affects the cost efficiency of ASD surgery. PURPOSE: Investigate the differences in ASD surgery cost for metabolic syndrome patients. STUDY DESIGN/SETTING: Retrospective review of a single center ASD database. PATIENT SAMPLE: A total of 557 ASD patients. OUTCOME MEASURES: Complications, revisions and costs.
METHOD(S): ASD patients (scoliosis >=20degree, SVA>=5cm, PT >=25degree, or TK >=60degree) >=18, undergoing >=4 level fusions were included. Descriptive analysis assessed mean baseline demographic, radiographic and surgical data were assessed. Patients diagnosed with: BMI >30, diabetes mellitus, and HTN were classified metabolic syndrome patients (MetS). Independent samples T-tests assessed baseline differences in SVA, PT, PI-LL, and levels fused between MetS and non-MetS patients. Total surgery costs for MetS and non-MetS ASD patients were compared. Costs were calculated using the PearlDiver database, which reflects both private insurance and Medicare reimbursement claims. Complications and comorbidities (CC) and major complications and comorbidities (MCC) were assessed according to CMS.gov manual definitions.
RESULT(S): A total of 557 patients met inclusion criteria. Baseline demographics and surgical details: age 60.8 +/- 13.2, 67.5% female, BMI 28.3 +/- 6.67, 6.2% anterior approach, 81.0% posterior approach, 12.8% combined approach, 10.4 +/- 3.9 levels fused, op time 423.5 +/- 166.4 minutes, EBL 2061.4 +/- 1631.5 cc, LOS 7.6 +/- 5.4 days. 11 MetS patients were included. There was no significant difference in BL SVA (54.2degree vs 70.3degree), PT (26.7degree vs 23.7degree), PI-LL (16.4degree vs 21.2degree), or levels fused between groups (10.5 vs 10.6) (all p>0.05). Twenty-seven percent of MetS patients experienced a CC or MCC, with 18% undergoing revisions within 90 days (vs 13.2% and 3.2% for non-MetS, p<0.05). The average costs of surgery for MetS patients was $68,004.06 vs $48,726.40 for non-MetS patients (p<0.05).
CONCLUSION(S): Metabolic syndrome is a growing concern among health care providers. In metabolic syndrome patients undergoing corrective adult spinal deformity surgery, the total costs of surgery was 28.4% higher for metabolic syndrome patients ($68,004.06 vs $48,726.40). Optimizing modifiable factors like diabetes or BMI in preoperative patients may have an impact on cost effectiveness. 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 (BMP) is increasingly utilized in minimally invasive (MIS) transforaminal lumbar interbody fusions (TLIF) in order to increase rate of fusion by promoting bone growth through the induction of osteoblast differentiation, awhile reducing morbidity related to iliac crest autograft. Despite these benefits, BMP use is still controversial due to its pro-inflammatory mechanism of action and potential to cause radiculitis. PURPOSE: To assess whether BMP is a risk factor for postoperative radiculitis in TLIF. STUDY DESIGN/SETTING: Single-center retrospective cohort study. PATIENT SAMPLE: A total of 397 TLIFs from June 2012 to December 2018. OUTCOME MEASURES: Perioperative clinical characteristics, post-operative risk of radiculitis and complication, and future reoperation rates.
METHOD(S): Patients >= 18 years-old undergoing elective single-level TLIFs from 2012 to 2018 were included. Outcome measures included perioperative clinical characteristics, postoperative risk of radiculitis and complication, and future reoperation rates. Radiculitis was defined the delayed onset of radicular symptoms postoperatively in patients whom had initial resolution of radicular symptoms immediately postoperatively, in the absence of persistent neurological compression on postoperative imaging. Statistical analyses included independent t-tests and chi-square analysis. Propensity score matching was utilized to control for demographic differences between the groups. Independent predictors for post-operative radiculitis were assessed by multivariate logistic regression. Significance set at p<0.05.
RESULT(S): A total of 397 cases were included in the study (59.33 +/- 13.49 mean age, 28.98 +/- 6.29 mean BMI, 52.90% female, 2.29 +/- 1.92 average Charleston comorbidity Index). There were 223 open procedures and 174 MIS. For the entire cohort, 238 cases utilized BMP and 159 did not, with 102 MIS pairing with BMP use. The MIS TLIFs had a higher percentage of BMP use than open TLIFs (58.6% vs 25.7%, p<0.001), lower estimated blood loss (212.28 +/- 193.79 mL vs 410.91 +/- 337.98 mL, p<0.001) higher fluoroscopy dosage (52.43 +/- 48.61mGy vs 16.77 +/- 27.84mGy, p<0.001), and a lower length of stay (3.20 +/- 2.55 days vs 4.11 +/- 2.52 days, p<0.001). There were no other differences in perioperative clinical characteristics. There was a significantly higher rate of postoperative radiculitis in the MIS TLIFs compared to open (12.6% vs 6.8%, p=0.046) and use of BMP compared to no BMP (13.2% vs 6.7%, p=0.029). There was a 15.7% radiculitis rate when MIS was paired with BMP use. There were no other notable differences in complication rates or rates of reoperation. Individually, MIS had a 12.6% radiculitis rate (p=0.046) and BMP use had a 13.2% rate (p=0.029). Propensity score match controlled for the significant difference in CCI between the MIS and open groups (N=168 each). Multivariate regression indicated that MIS (p=0.314) and BMP (p=0.109) were not independent predictors individually when controlling for age, gender, and BMI. When technique was paired with biologic use the regression revealed MIS + BMP is a risk factor of post-operative radiculitis (2.265(4.753-1.079), p=0.031).
CONCLUSION(S): While BMP and MIS technique were not independent risk factors for postoperative radiculitis, there is an increased risk of radiculitis when using BMP in MIS TLIF. FDA DEVICE/DRUG STATUS: This abstract does not discuss or include any applicable devices or drugs.
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BACKGROUND CONTEXT: Following cervical deformity (CD) corrective surgery, durability remains a challenge and distal junctional kyphosis (DJK) is an important risk for a surgeon to consider. DJK is the result from fixation failure, adjacent level fracture or spondylolisthesis. The timing of DJK onset has yet to be investigated. PURPOSE: To determine the timing of DJK development following CD corrective surgery. STUDY DESIGN/SETTING: Retrospective review. PATIENT SAMPLE: A total of 139 CD patients. OUTCOME MEASURES: Early/Late DJK Development, Severe DJK, Symptomatic DJK.
METHOD(S): Included: surgical CD patients (C2-C7 Cobb>10degree, CL>10degree, cSVA>4cm, or CBVA>25degree) without preop DJK. DJK angle was defined as the change in kyphosis between lower-most instrumented vertebra (LIV) and LIV-2 from preop to postop (<-10). X2 analysis and post-hoc testing assessed annual and overall incidence of early (3M follow-u) and late (DJK development at 6M, 1Y, 2Y) DJK development among operative patients. Differences between early and late DJK (development after 3 months) were assessed. Pearson correlations determined significant variables associated with development of early versus late DJK. Severe DJK was defined as DJK angle <-20degree. DJK was considered symptomatic if associated with reoperation or the previously published thresholds of NDI>24 or mJOA<14. The natural progression of the disease was predicted with the use of a Kaplan-Meier survivorship analysis.
RESULT(S): A total of 139 patients without preop DJK were included (16 re-op) (61.8yrs, 62.3%F, 29.1kg/m2). Surgical characteristics: 20.1% anterior approach, 42.4% posterior, 36.7% combined (levels fused: 7.6). Incidence of DJK from 2013-2018: 23%. Early: 9.4%, late: 10.1% (6M delayed: 3.6%, 1Y delayed: 6.5%, 2Y delayed: 2.2%). No differences were observed between op and reop for development of early or late DJK at all f/u (p>0.050). Presence of upgoing plantar response at baseline neuro exam, C2-C7 angle, T1-C2 angle, CBVA and combined approach correlated with development of early DJK. For late DJK: history of tumor and pulmonary disease, pelvic incidence, T10-L2 angle, and L4 pelvic angle. Apex of the secondary driver was significantly lower in the Late group (mean early: T2/3; late: T10; p=0.023). 3M radiographically, Early DJK patients had greater TK (-57.9degree vs -40degree, p=0.024, while L4PA remained larger in the late DJK group (14.5degree, p=0.009). Between early and late groups, 41.7% of early DJK patients met criteria for severe DJK, while 0% of Late DJK patient were severe(p=0.010); symptomatic DJK between the two groups was not significant (p=0.941). Kaplan-Meier survivorship analysis determined patients within the cohort to have a 91.1% cumulative probability of maintaining non-DJK status by 3-month follow-up, 85.9% at 6-month, 80% at 1-year, and 77.0% by 2-year follow-up.
CONCLUSION(S): Patients undergoing CD corrective surgery have incidence of early and incidence of late DJK. While the majority of DJK development occurs within the first 6 months, late DJK occurs and differs in presentation and etiologic factors. Early DJK occurrence is more likely to be severe radiographically, associated with neurological decline, and is more strongly related to biomechanical factors such as use of a combined approach at the time of surgery. Contrarily, although equally likely to be symptomatic as reflected in loss of clinical gains from surgery, late DJK is more likely mild radiographically and associated with suboptimal cervical realignment and lack of addressing secondary drivers, likely related to negative compensatory mechanisms. Customized prophylactic approaches for both occurrences is mandated. FDA DEVICE/DRUG STATUS: This abstract does not discuss or include any applicable devices or drugs.
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BACKGROUND CONTEXT: The Scoliosis Research Society established appropriateness criteria for surgery for degenerative lumbar scoliosis (DLS) in order to improve and unify clinical decision making. Though utilized and validated in various cohorts, an appropriateness criteria has yet to be developed in a cervical deformity (CD) population. PURPOSE: To modify the DLS Appropriateness criteria to be utilized in a CD cohort. STUDY DESIGN/SETTING: Retrospective review of a single-surgeon CD database PATIENT SAMPLE: A total of 100 CD patients. OUTCOME MEASURES: Appropriateness criteria.
METHOD(S): CD patients>18yrs were included. Each patient was scored based upon the SRS-appropriateness criteria, comprised of clinical or radiographic characteristics and was modified for a cervical deformity cohort: (1) Severity of Symptoms [NDI], (2) Severity of Myelopathy[mJOA.], (3) Progression of Deformity, (4) Global Sagittal Malalignment [Schwab modifiers], (5) Severity of Risk Factors, (6) Degree of the T1S-CL curvature. For the category 'progression', radiographs were only available at one preoperative time point, and we were unable to include this in the total score. Based upon certain combinations of criteria, patients were stratified into Appropriate and Not Appropriate.
RESULT(S): A total of 100 patients were included (61yrs, 62% F, 29.5kg/m²). Assessment of the categories of Appropriateness of CD surgery: (1) Symptoms: 6% None to Mild, 94% Moderate to Severe; (2) Myelopathy: 16% None to Mild, 45% Moderate, 39% Severe; (3) All were grouped No Progression in the present study; (4) 19% demonstrated Global Malalignment (+/++Schwab), 81% did not; (5) Risk Factors: 27% had None to Mild, 63% Moderate, 10% Severe; (6) Curvature TS-CL demonstrated 88.6% of patients Severe (>20degree). Not Appropriate: None to Mild (NDI <28), with (1) None to Moderate myelopathy (mJOA >12) and Severe Risk Factors (2) None to Mild myelopathy (15-18) and No Progression or Imbalance (3) Moderate myelopathy (mJOA 12-15) and None to Moderate Risk Factors and no Progression, or imbalance and TSCL <25degree. Appropriate: Moderate to Severe Symptoms (NDI >=30), with (1) Severe myelopathy (mJOA<12) and Any Risk Factors (2) Moderate myelopathy and None to Moderate Risk Factors (3) Moderate myelopathy with Severe Risk Factors, Progression AND Imbalance (4) None to Mild myelopathy and None to Moderate Risk Factors and Progression OR imbalance (5) None to Mild myelopathy with None to Moderate Risk Factors and TSCL >25degree. In the present cohort, 94% were deemed Appropriate for surgery, 6% Not Appropriate. Less Appropriate patients demonstrated higher rates of postop dysphagia complications (17% vs 2%), met MCID for NDI less (0% vs 30.9%), and had more occurrences of DJK (16.7% vs 6.4%) by 2 years, p<0.05.
CONCLUSION(S): In light of the heterogeneity and uncertainty surrounding CD, this study developed CD appropriateness criteria, using established methodology, for surgeons to consider in the preoperative decision-making that correlate well with major postop occurrences. Application of the appropriateness criteria for CD may optimize patient selection and reduce the incidence of unwarranted surgery, although future validation is necessary. FDA DEVICE/DRUG STATUS: This abstract does not discuss or include any applicable devices or drugs.
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BACKGROUND CONTEXT: Adult spinal deformity (ASD) corrective surgery is often associated with high rates of adverse outcomes during the recovery course. With the growth of predictive analytics in the medical field, it is important to utilize the developing machine-learning resources to consider the risks associated with major operations. PURPOSE: To assess the validity of the ACS-NSQIP risk index for postop complications and mortality in a prospective multicenter ASD database. STUDY DESIGN/SETTING: Retrospective cohort study of a prospective multicenter ASD database PATIENT SAMPLE: A total of 1,281 ASD patients. OUTCOME MEASURES: Predictive performance of the ACS-NSQIP calculator in an ASD database.
METHOD(S): Patients>18yrs undergoing surgery for ASD (scoliosis>=20degree, SVA>=5cm, PT>=25degree or TK>=60degree). Calculated perioperative complication risk averages via the ACS-NSQIP surgical calculator with CPT codes were compared with 30-day complication rates in the ASD database. Outcomes assessed (as defined by NSQIP): serious complication, any complication, pneumonia, cardiac complication, SSI, UTI, VTE, renal failure, return to OR, death, sepsis and length of hospital stay. Predictive performance of the calculator was analyzed by Brier score (sum of squared differences between the binary outcome and the predicted risk). It ranges from 0 to a maximum Brier score [(mean observed outcome)*(1-[mean observed outcome])]. Values closer to 0 are suggestive of better predictive performance (>0.05 considered poor). Length of stay was assessed with a Bland-Altman plot, observed LOS on the x-axis and the difference between the observed and predicted LOS on the y-axis. Performance of the calculator for serious/any complications for surgeries indicated as 'Risk significantly higher than estimate' was assessed by comparing means of patients who were in the top quartile for their ISSG-invasiveness scores.
RESULT(S): A total of 1,281 ASD patients (60.2 yrs, 73.5% F, 28 kg/m2) were included. A total of 49.4% of procedures involved decompression and 100% involved fusion, with a mean number of levels fused of 10.98. The means for individual patient characteristics that coincide with the variables entered into the online risk calculator interface are as follows: functional status through baseline ODI scores (Independent [0-40]: 35.6%, Partially Dependent [41-80]: 61.8%, Totally Dependent [81+]: 2.6%), 0% emergent cases, ASA Class (I: 5.6%, II: 46.8%, III: 41.7%, IV: 1.4%, V: 0%), 11.9% disseminated cancer, 9.1% diabetes mellitus, 36.5% use of hypertensive medications, 10.8% CHF, 5.9% current smoker, 5.2% COPD, and 4.4% acute renal failure. Predictive of any 30-day postoperative complications ranged from 2.8-18.5% across CPT codes, where the actual rate in the cohort was 9.0%, and demonstrated good predictive performance via Brier Score (0.00064516, Max: 0.00819), as well as pneumonia, SSI, UTI, VTE, renal failure, death and sepsis (Brier Max: 0-0.01458096). Serious and cardiac complications, as well as return to OR were poorly predicted via the NSQIP risk index (Brier Max > 0.05). Mean difference between observed and predicted LOS was 4.276 days with a 95% confidence interval of 9.484 - -0.932. When indicated for significantly high risk, the calculator poorly predicted overall and serious complications (Brier Max >0.1).
CONCLUSION(S): While the ACS-NSQIP risk index had acceptable predictive performance in regards to the occurrence of overall post-operative complications, notable exceptions were detected. Specifically, deficiencies in assessing serious complications, cardiac complication and return to OR were seen, and performance was noted to diminish with procedures of greater invasiveness. FDA DEVICE/DRUG STATUS: This abstract does not discuss or include any applicable devices or drugs.
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BACKGROUND CONTEXT: Prior studies have demonstrated potential benefits of adult spinal deformity (ASD) surgery, but less outcomes data exist for operative ASD patients with severe scoliotic curves (thoracic [TH] curve >=75degree, thoracolumbar [TL] curve >=50degree, or lumbar [LL] curve >=50degree). Also, the surgical complication profile is less clear for this subset of patients with severe scoliotic deformity and warrants focused investigation. PURPOSE: The objective of the current study was to assess treatment outcomes and complication rates associated with ASD surgery in patients with severe scoliosis. STUDY DESIGN/SETTING: Retrospective review of a prospectively collected multicenter consecutive case registry PATIENT SAMPLE: Enrollment required: age >=18 yrs, scoliosis >=20degree, sagittal vertical axis (SVA) >=5cm, pelvic tilt >=25degree, and/or thoracic kyphosis >=60degree. OUTCOME MEASURES: Standard coronal and sagittal spinopelvic deformity measurements and health-related quality of life (HRQL) outcomes, which included Oswestry Disability Index (ODI), Short Form-36 (SF-36) scores, and Scoliosis Research Society-22 (SRS-22) scores.
METHOD(S): Using a prospective multicenter database, we identified surgically treated ASD patients with severe scoliosis (TH Cobb >=75degree or TL/LL Cobb >=50degree) and minimum 2-yr follow-up. Demographic data, surgical characteristics, radiographic alignment measurements, HRQL outcomes and associated complications were analyzed.
RESULT(S): Of 178 patients, 146 (82%, mean age 54 yrs, 92% women, 88 TL, 50 LL, 8 TH) had minimum 2-yr follow-up (mean=3.1 yrs). Almost 30% had prior spine fusion, 6% were active or past smokers, 16% had osteoporosis and 77% had at least 1 comorbidity. Surgical details included: posterior-only (58%) or anterior-posterior approach (42%), SPO (65%), 3CO (14%), TLIF (23%), ALIF (37%), sacropelvic fixation (76%), upper thoracic UIV (64%) and mean posterior fusion length of 13.2 levels. Postoperative coronal alignment improved significantly for all patients (global coronal alignment 3.8 to 2.8 cm, p< 0.001; TH Cobb 38degree to 24degree, p<0.001; TL Cobb 61degree to 30degree, p<0.001; LL Cobb 50degree to 24degree, p<0.001; Fractional Cobb 20degree to 7degree, p<0.001). Overall sagittal alignment also improved significantly (p<0.05), most notably for severe lumbar curves (C7-S1 SVA 6.7 to 2.5 cm, p<0.001; PI-LL 18degreeto 3degree, p<0.001). Overall HRQL improved significantly, including ODI (39 to 26, p<0.001), SF-36 PCS (35 to 41, p<0.001) and SRS-22r (2.9 to 3.8, p<0.001). A total of 191 complications were reported (92 minor/99 major), and 94 (64%) patients had at least one complication. The most common complications included dural tear (12%), pleural effusion (12%), rod fracture (11%), radiculopathy (8%) and proximal junctional kyphosis (7%). 34 reoperations were performed in 27 (18%) patients, with most common indications of rod fracture/pseudarthrosis (8), deep wound infection (6) and neurological deficit (5).
CONCLUSION(S): Surgery for severe adult scoliosis is associated with significant improvement in radiographic alignment and HRQL measures. Although associated complication rates are high, these appear to be comparable to reports of less severe scoliosis. FDA DEVICE/DRUG STATUS: This abstract does not discuss or include any applicable devices or drugs.
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BACKGROUND CONTEXT: Lateral lumbar interbody fusion (LLIF) provides indirect decompression of the neural elements while minimizing the potential vascular complications associated with anterior lumbar interbody fusion (ALIF). Posterior fixation may be applied through various techniques such as conventional minimally invasive surgery (CMIS), requiring the patient to be repositioned prone to provide access to both pedicles. Conversely, robot-assisted navigation (RAN) of pedicle screws can be utilized from a single position without flipping the patient. RAN is theorized to reduce patient surgical time, radiation, and blood loss due to positioning and workflow effects. PURPOSE: To evaluate the effect of robot-assisted navigation in comparison to CMIS methods in terms of surgical time, radiation exposure, and pedicle screw accuracy. STUDY DESIGN/SETTING: Cadaveric study. PATIENT SAMPLE: N/A OUTCOME MEASURES: N/A METHODS: Twelve unembalmed human torsos were implanted with 2-level static LLIF cages, followed by posterior bilateral pedicle screw fixation using either CMIS (n=6) or RAN (n=6). Preoperative computed tomography (CT) RAN workflow utilized CT scans of the specimen taken offsite and transferred to the robotic system during setup. Screw planning was performed using these CT scans, and then was merged with intraoperative fluoroscopy. Surgical times, surgeon radiation exposure, and screw accuracy were measured. Patient flip time from a consecutive patient series was included.
RESULT(S): Significant differences in surgical times and radiation dosages were found between groups. Surgical time for preoperative RAN and CMIS was 64.7 min+/-4.1 min and 123.0 min+/-13.7 min, respectively. Time per screw for RAN and CMIS workflows was 2.7+/-0.6 min and 4.3+/-1.3 min, respectively. RAN was significantly different for total operative time and time per screw in comparison to CMIS (p<0.05). Radiation dosages and times were separated into interbody and posterior fixation procedures separately, and sorted by imaging workflow. RAN and CMIS radiation dosages during posterior fixation were 0.4+/-0.2 rad and 2.7+/-1.6, respectively (p<0.05). Screw accuracy was as follows: CMIS resulted in 4 breaches (11% breach rate), while RAN resulted in a single breach (3% breach rate).
CONCLUSION(S): Significant differences were found in both surgical time and radiation exposure between CMIS and RAN, with RAN resulting in shorter surgical times and less radiation exposure to the surgeon than CMIS. Consideration should be given to single-position LLIF procedures that utilize RAN to instrument the spine with bilateral pedicle screws. FDA DEVICE/DRUG STATUS: This abstract does not discuss or include any applicable devices or drugs.
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BACKGROUND CONTEXT: Traditionally, adult spinal deformity (ASD) has been treated with long segment fusions with the goal of restoring sagittal and coronal alignment. Long segment fusions can be associated with high rates of complications and morbidity. Some patients are reluctant to undergo large procedures. Others have comorbidities excluding them as good surgical candidates for long fusions. PURPOSE: To compare baseline and postoperative HRQL and radiographic outcomes and revisions and complications in small vs longer fusions for ASD. STUDY DESIGN/SETTING: Retrospective analysis of a prospective, multicenter database PATIENT SAMPLE: Surgical ASD patients OUTCOME MEASURES: ODI, SF36-PCS, SRS22, NRS back and leg pain.
METHOD(S): A prospective database of operative ASD patients who completed two year follow up was analyzed. Prior thoracolumbar fusions were excluded. Patients were divided into short fusions (SF: 3 levels) and long fusions (LF: 36 levels). LF and SF patients were compared in baseline alignment. Propensity matching (PSM) controlling for baseline alignment (TPA and maximum coronal cobb) was performed to compare SF and LF in HRQL improvement, postop alignment and complications. Subanalysis of SF identified which patients were more likely to have successful surgery. The level of significance was p<0.05.
RESULT(S): A total of 298 patients met inclusion criteria (SF n=20, mean levels fused 2.13; LF n=275, mean fusion levels 12.33). Prior to PSM, LF had greater PT, coronal cobb, and TPA. Following PSM, LF had better improvements in PILL (20.8 vs 3.37), PT (8.57 vs 0.21), TPA (8.68 vs 2.07), and coronal cobb (17.3 vs 5.33) all p<0.005. There were no differences in 2y HROL improvement, satisfaction or reoperations. SF had fewer complications (OR 0.15, p=0.018). In the SF group, the deformities were 15% sagittal, 40% coronal, and 45% combined. In the sagittal group, 67% of surgery aimed at deformity correction but 67% of these required revision long fusion surgery. In the coronal group, 38% of surgery aimed at deformity correction with no revisions. In the combined group. 67% of surgery aimed at deformity correction but 11% of these required revision long fusion surgery.
CONCLUSION(S): This study shows that a more limited fusion could be an alternative to the more traditional long segment fusion in carefully selected patients with adult spinal deformity since there were fewer complications but similar short-term (2-year) satisfaction rates and HRQL improvements. Patients undergoing long fusions had better improvements in alignment. The majority of sagittal only deformities undergoing short fusions required revision surgery. The durability of short fusions in the setting of ASD needs to be investigated with long term studies. FDA DEVICE/DRUG STATUS: This abstract does not discuss or include any applicable devices or drugs.
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