Faculty Bibliography

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.
Copyright

BACKGROUND CONTEXT: Frailty has been utilized in cervical deformity (CD) to characterize the influence of preop health state on postop outcomes. Frailty severity may be an important determinant for impaired recovery after CD corrective surgery. No prior studies have examined the associations between increasingly frail states and the trajectory of recovery in CD realignment. PURPOSE: Evaluate postop clinical recovery among CD patients between frailty states undergoing primary procedures STUDY DESIGN/SETTING: Retrospective review of a prospective CD database PATIENT SAMPLE: A total of 106 CD patients. OUTCOME MEASURES: Baseline (BL) to 1-Year(1Y) HRQL Instruments: NDI, mJOA, EQ5D METHODS: Patients>18yrs undergoing surgery for CD (C2-7 Cobb>10degree, coronal Cobb>10degree, cSVA>4cm or TS-CL>10degree, or CBVA>25degree) with HRQL data at BL, 3M and 1Y postop intervals were identified. Patients were stratified by the modified CD frailty index (mCD-FI, Passias et al.) scale from 0-1 (no frailty:<0.3[NF], mild/severe: >0.3[F]). Patients in NF and F groups were propensity score matched (PSM) for TS-CL to control for baseline deformity. Demographics, alignment and Ames-ISSG deformity modifiers were assessed using chi-squared and paired t-tests to compare HRQL outcomes. HRQL outcomes were normalized by dividing BL and postop (3M, 1Y) outcomes by BL for each patient. Normalized scores (y-axis) were plotted against duration of follow-up (x-axis). AUC was calculated for follow-up time intervals; total area for each follow-up interval was divided by cumulative follow-up, determining overall normalized, time-adjusted HRQL outcomes (Integrated Health State [IHS]). IHS was compared between NF and F groups.
RESULT(S): A total of 106 CD patients included (61.7yrs, 66% F, 27.7kg/m2). By frailty group: 52.8% NF, 47.2% F. After PSM for TS-CL (mean: 38.1degree), 38 patients remained in each of the NF and F groups. By surgical approach, 46.1% underwent posterior approach, 19.7% anterior, and 34.2% combined; which was not significant between the frailty groups(p>0.05). At baseline, cervical and spinopelvic radiographic parameters were not significant, except for the C7-S1 SVA (NF: -26.5mm vs F: 15.2mm, p=0.007). According to BL HRQLs, F patients displayed significantly worse NDI scores (NF: 36.8 F: 55.4; p<0.001), mJOA (NF: 14.7, F: 12.7; p=0.002), and EQ5D (NF: 0.78, F: 0.69; p<0.001). All frailty groups exhibited BL to 1Y improvement in NDI, EQ5D and NRS Neck Pain (all p<0.001). After HRQL normalization, F patients had more improvement in mJOA scores at 3M (p=0.065) as well as NDI (p=0.096) and EQ5D (p=0.016). IHS-adjusted HRQL outcomes from BL to 1Y showed a significant difference in EQ5D scores (NF: 1.02, F: 1.07, P=0.016). No significant differences were found in the IHS NDI and mJOA between frailty groups (p>0.05). F patients had more postop major complications (31.3%) compared to the NF (8.9%), p=0.004, though DJK occurrence and reoperation between the groups was not significant.
CONCLUSION(S): While all groups exhibited improved postop disability/pain scores, frail patients recovered better in overall health state. Despite frail patients having more complications, they seem to have overall better patient-reported outcomes, signifying that with frailty severity, patients have more room for improvement postop compared to baseline quality of life. FDA DEVICE/DRUG STATUS: This abstract does not discuss or include any applicable devices or drugs.
Copyright

BACKGROUND CONTEXT: With the rise of health care costs and a focus on value-based outcomes, hospitals have become more cognizant on cost of revisions and complications. However, literature on the effect of distal junctional kyphosis in driving up health care costs is scarce. PURPOSE: To evaluate the effect of distal junctional kyphosis on the cost effectiveness of corrective cervical deformity surgery. STUDY DESIGN/SETTING: Retrospective review of a single surgeon database. PATIENT SAMPLE: This study included 123 cervical deformity patients. OUTCOME MEASURES: Cost per QALY.
METHOD(S): Cervical deformity patients with minimum 1-year HRQL follow-up were included. Means comparison tests assessed differences in baseline demographic and clinical data. Utility data was calculated using published conversion methods to convert NDI to SF-6D. QALYs utilized a 3% discount rate to account for residual decline to life expectancy (78.7 years). Costs was calculated using the PearlDiver database incorporating complications, comorbidities (CC), major complications, and comorbidities (MCC) were assessed according to CMS.gov manual definitions. Reimbursement consisted of a standardized estimate using regression analysis of Medicare pay-scales for all services rendered within a 30-day window, including estimates regarding costs of postoperative complications, outpatient health care encounters, revisions and medical-related readmissions. After accounting for CC, MCC, length of stay (LOS) and death, cost per QALY at 2Y was calculated for revisions due to distal junctional kyphosis.
RESULT(S): A total of 123 cervical deformity patients met inclusion criteria (57.22yrs, 54%F, 29.0kg/m2). At baseline, patients presented radiographically as: PT (16.9+/-9.7), PI (54.7+/-11.4), PI-LL (-2.9+/-12.6), SVA (80.5+/-49.8), cSVA (28.4+/-20.6), TS-CL (26.6+/-14.4). Surgical details: EBL of 708 mL, operative time of 438.6 min, with 29.51% undergoing an anterior approach, 50.82% posterior-only approach, and 19.67% combined approach. Overall, 7.9% of patients developed DJK within two years postoperatively. Average cost of revision surgery due to DJK within 2years of index surgery was $50,736 +/- 31,467. Patients that developed DJK within 2years of index surgery trended toward having a greater baseline NDI (62.8 vs 55.47, p>0.05) and showed less improvement in NDI at 2 years (4 vs 16.6). Overall, cost per QALY was higher for patients developing DJK at 2 years ($28,483 vs $20,989).
CONCLUSION(S): Cervical deformity revisions due to distal junctional kyphosis had a cost per QALY of $28,483. Efforts to limit postoperative DJK after surgical intervention can further limit additional costs associated with revisions and complications. FDA DEVICE/DRUG STATUS: This abstract does not discuss or include any applicable devices or drugs.
Copyright

BACKGROUND CONTEXT/BACKGROUND:Considerable debate exists regarding the optimal surgical approach for adult spinal deformity (ASD). It remains unclear which approach, posterior-only or combined anterior-posterior (AP), is more cost-effective. Our goal is to determine the 2-year cost per quality-adjusted life year (QALY) for each approach. PURPOSE/OBJECTIVE:To compare the 2-year cost-effectiveness of surgical treatment for ASD between the posterior-only approach and combined AP approach. STUDY DESIGN/METHODS:Retrospective economic analysis of a prospective, multicenter database PATIENT SAMPLE: From a prospective, multicenter surgical database of ASD, patients undergoing 5 or more level fusions through a posterior-only or AP approach were identified and compared. METHODS:QALYs gained were determined using baseline, 1-year, and 2-year post-operative Short Form 6D. Cost was calculated from actual, direct hospital costs including any subsequent readmission or revision. Cost-effectiveness was determined using cost/QALY gained. RESULTS:The AP approach showed significantly higher index cost than the posterior-only approach ($84,329 vs $64,281). This margin decreased at 2-year follow-up with total costs of $89,824 and $73,904, respectively. QALYs gained at two years were similar with 0.21 and 0.17 in the posterior-only and the AP approaches, respectively. The cost/QALY at two years after surgery was significantly higher in the AP approach ($525,080) than in the posterior-only approach ($351,086). CONCLUSIONS:We assessed 2-year cost-effectiveness for the surgical treatment through posterior-only and AP approaches. The posterior-only approach is less expensive both for the index surgery and at 2-year follow-up. The QALY gained at 2-years was similar between the two approaches. Thus, posterior-only approach was more cost-effective than the AP approach under our study parameters. However, both approaches were not cost-effective at 2-year follow-up.

BACKGROUND CONTEXT: This study evaluates the necessity of a multi-rod construct to help prevent a pseudarthrosis in ASD surgery of lesser magnitude. Regardless of an interbody at L5/S1, a multi-rod construct does not decrease the risk of developing a pseudarthrosis. If a pseudarthrosis develops in patients who undergo an interbody fusion at L5/S1, it is more likely to occur above the L5/S1 level and the number of rods used does not decrease this risk. PURPOSE: To examine the necessity of IBF and multi-rod use to prevent pseudarthrosis in these lesser magnitude ASD surgeries. STUDY DESIGN/SETTING: Retrospective review of a multicenter database. PATIENT SAMPLE: A total of 483 patients met our inclusion criteria of pelvic fixation, > 2 year follow up, >5 levels fused, no 3-column osteotomy (3CO), and no multi-level interbody fusions. OUTCOME MEASURES: Pseudarthrosis rate and location in ASD patients.
METHOD(S): A multi-center database was evaluated to identify patients with pelvic fixation, > 2 year follow up, >5 levels fused, and no 3-column osteotomy (3CO). We define a lesser magnitude ASD surgery as surgeries that do not include 3CO or multi-level interbody fusions. In this cohort, ASD patients with and without an IBF at L5/S1 were assessed to evaluate if the number of rods had an impact on the pseudarthrosis rate. Pseudarthrosis was determined by intraoperative findings or record review. Fisher's exact tests, univariate and multivariate analysis were used to identify predictors of pseudo.
RESULT(S): A total of 483 patients met our inclusion criteria with an average follow-up of 48 months. Of those, 321 (66%) had interbody at L5/S1 (IBF). Twenty-three percent of IBF patients had a MR construct and 77% had a SR construct. In the non-IBF group, 33% had a MR construct. In the IBF group, the MR construct did not impact the pseudarthrosis rate compared to a SR construct, (6.8% vs 5.2% respectively, p=.35). In the IBF group, 29% (4) of MR patients and 75% (6) of SR patients with pseudo received BMP. However, regardless of the rod construct, ASD patients with an interbody at L5/S1 had an increased risk of having a pseudarthrosis above this level (OR.096, p=.045). Also, the MR construct did not decrease the risk of developing a pseudarthrosis in the non-IBF group (0% vs 4.5%, p=.18).
CONCLUSION(S): In ASD surgery of lesser magnitude, a multi-rod construct does not decrease the risk of developing a pseudarthrosis. Patients who have an interbody fusion at L5/S1 are more likely to develop a pseudarthrosis above this level, regardless of the rod construct. FDA DEVICE/DRUG STATUS: This abstract does not discuss or include any applicable devices or drugs.
Copyright

BACKGROUND CONTEXT: Prior studies demonstrated that symptomatic adult spinal deformity (SASD) is a heterogeneous condition with varying degrees of negative health impact depending on the specific type and severity of deformity. Currently, there is some controversy regarding the subset of SASD with global coronal malalignment (GCM) and its associated health impact. Moreover, few reports have assessed the health impact of this global coronal parameter in comparison to other deformity types. A comparative study of deformity types with severe global malalignment (eg, severe GCM) may provide clinically relevant insights and identify potential differences in demographics and health impact. PURPOSE: To compare demographics and health impact of SASD patients with severe global malalignment (primary sagittal [SAG-only] vs primary coronal [COR-only] vs sagittal+coronal [MIX]). STUDY DESIGN/SETTING: Retrospective analysis of a prospective multicenter database. PATIENT SAMPLE: Enrollment required age >=18 yrs and one of the following: scoliosis >=20degree, sagittal vertical axis (SVA) >=5cm, pelvic tilt >=25degree, and/or thoracic kyphosis >=60degree. OUTCOME MEASURES: Short Form-36 (SF-36) PCS score.
METHOD(S): Consecutive SASD patients from a prospective multicenter database were evaluated for type and severity of global malalignment. Severe alignment thresholds included SVA >=10cm (SAG-only), GCM >=6cm (COR-only), or both SVA >=10cm and GCM >=6cm (MIX). SF-36 PCS scores were compared with U.S. normative values.
RESULT(S): Of 492 SASD patients that met threshold alignment criteria, 463 (94%) completed the SF-36 and were included (78% women, mean age 65 years, mean BMI 28.6 kg/m2, previous spine surgery in 65%). Deformity types were SAG-only (58%), COR-only (19%) and MIX (23%). COR-only had more women (94%, p<0.001), younger age (61 years, p=0.004), and lower BMI (26 kg/m2, p<0.001). Charlson Comorbity Index (CCI) scores and total number of comorbidities were comparable among the deformity types (p>0.05). All deformity types were 'frail' based on ASD-Frailty Index scores (SAG-only [3.9], COR-only [3.1], MIX [4.0]). Overall mean PCS was lower compared to similar age- and gender-matched U.S. normative values (29.0 vs 45.3, p<0.001). Mean PCS was significantly different between deformity types (p<0.001): SAG-only (28.5) vs COR-only (33.1) vs MIX (27.0). PCS offsets from normative population scores were significantly different between deformity types (p=0.001): SAG-only (-16.6) vs COR-only (-13.4) vs MIX (-18.2).
CONCLUSION(S): Demographic comparisons demonstrated significantly more women, younger age, and lower BMI in the COR-only deformity type. Severe global malalignment (SVA >=10cm and/or GCM >=6cm) had substantial debilitating impact on health, with MIX deformity type (i.e., severe global sagittal and coronal malalignment) experiencing the greatest health impact. FDA DEVICE/DRUG STATUS: This abstract does not discuss or include any applicable devices or drugs.
Copyright

BACKGROUND CONTEXT: The choice of surgical approach in CD surgery is often dictated by surgeon preference and experience. This choice could significantly impact the costs and outcomes of an operation, therefore the approaches should be analyzed in order to determine the optimal approach from a cost-utility perspective. The cost utility of different surgical approaches in cervical deformity (CD) has not been investigated in the literature. PURPOSE: Investigate the cost utility of differing approaches in operative CD patients. STUDY DESIGN/SETTING: Retrospective review of a prospective multicenter cervical deformity database. PATIENT SAMPLE: A total of 105 CD patients. OUTCOME MEASURES: Costs, EuroQol-5D (EQ-5D), Quality adjusted life years (QALYs), Cost per quality adjusted life years.
METHOD(S): Included CD patients (C2-C7 Cobb>10degreeor CK>10degree, cSVA>4cm or CBVA>25degree) >18yr with follow-up (1-year) surgical and health related quality of life scores. Costs were calculated using the PearlDiver database, which reflects both private insurance and Medicare reimbursement claims. QALYs and cost per QALY were calculated using a 3% discount rate to account for residual decline to life expectancy (78.7 years). After accounting for complications, LOS, revisions, and death, cost per QALY at 1Y and life expectancy [LE] were calculated for surgical approach (anterior-only, posterior-only [excluding PSO and VCR to account for differences in instrumentation], combined). In a subanalysis, approach groups were propensity-score matched for TS-CL to account for baseline (BL) deformity.
RESULT(S): A total of 105 CD patients met inclusion criteria (61.9 yrs, 63% female, 28.6kg/m2, CCI: 0.97). By approach, 21.9% underwent anterior only, 37.1% posterior only and 41% combined approaches. Average number of levels fused was 6.9, with a mean EBL of 948 ml and total operative time of 544.2 minutes. Mean EQ5D at BL was 0.74+/-0.07 and at 1Y was 0.79+/-0.08 (a difference of 0.05+/-0.08). Average difference in EQ5D from BL to 1Y was significant (p=0.002) across approach: 0.093 anterior-only, 0.021 posterior-only, 0.044 combined. 13% (3) of anterior-only patients underwent a revision, 10.3% (4) of posterior and 13.9% (6) of combined approaches. The average costs per surgery for CD patients at 1-year undergoing surgery by anterior approach was $27,640.75, $38,499.44 posterior-only, and $36,553.41 combined approach (p>0.05).The cost per QALY was higher for posterior-only patients at 1-year ($948,946.81) compared to anterior-only ($152,616.65) and combined ($424,110.14), p<0.001. If the utility gained was sustained to life expectancy, the cost per QALY for the anterior-only group was $21,665.87, posterior-only was $134,715.06 and combined approach was $60,207.82., p<0.001. After PSM for TS-CL, 15 patients remained in each group. The cost per QALY remained higher for posterior-only patients at 1-year and LE (both p<0.050).
CONCLUSION(S): After accounting for comorbidities, complications, revisions, and death, all surgical approaches showed improvement in postoperative EQ5D scores, however posterior approach demonstrated overall lower cost effectiveness. CD patients who underwent anterior-only approach had the lowest average costs for CD corrective surgery, as well as the lowest cost per QALY (best cost-effectiveness) compared to posterior and combined approaches. FDA DEVICE/DRUG STATUS: This abstract does not discuss or include any applicable devices or drugs.
Copyright

BACKGROUND CONTEXT: Cervical deformity (CD) severity has been linked to poor quality of life and severe neck pain. However, little is known of the relationship between surgical invasiveness accounting for cervical deformity severity and frailty status. PURPOSE: Investigate the outcomes of CD surgery by invasiveness, frailty status and baseline degree of deformity. STUDY DESIGN/SETTING: Retrospective cohort study. PATIENT SAMPLE: Ninety-six CD patients. OUTCOME MEASURES: HRQL measurements: NDI, EQ5D, mJOA.
METHOD(S): Inclusion criteria was defined as operative CD patients (C2-C7 Cobb>10degreeor CK>10degree, cSVA>4cm or CBVA>25degree) >18yr with follow up (1-year) radiographic and HRQL scores, NDI, mJOA and EQ5D. Patients were stratified by severity of deformity by TS-CL, categorized by the new-mJOA based modifiers: Low/Mod <45degree (Low-Mod); Severe >45degree(Sev). Frailty scores were calculated based upon the modified CD frailty index by Passias et. Al and categorized into severely frail (SF) >=0.5 and not SF (N-SF)<0.5. Patients were categorized by their frailty and deformity status (Low-Mod/N-SF; Low-Mod/SF; Sev/N-SF; Sev/SF). Logistic regression analysis assessed the relationship between increasing invasiveness and outcomes (DJK, complications). Within the significant frailty/deformity risk groups, decision tree analysis assessed thresholds for an invasiveness severity cut-off point, below which experiencing a reoperation, complication, DJK occurrence and poor mJOA were higher.
RESULT(S): Ninety-six CD patients met inclusion criteria (62.2+/-10.2 years, 66% female, 28.4+/-7.4 kg/m2). By approach: 19.8% anterior-only, 47.9% posterior-only, 32.3% combined (levels fused: 7.7+/-3.9). By deformity severity: 23.7% Low, 40.9% Moderate, 34.4% Severe, while frailty assessment placed 32.3% in N-SF and 67.7% SF. This categorized the patients into deformity/frailty groups as follows: 19.8% Low-Mod/N-SF(19), 13.5%(13) Sev/N-SF, 44.8%(43) Low-Mod/SF, 21.9%(21) Sev/SF. Logistic regression analysis found a significant relationship between increasing deformity severity and occurrence of severe postop DJK(1.053 [1.016-1.093], p= 0.005), complications(1.045 [1.012 - 1.080], p=0.007), revision by 1-year(1.059 [1.000-1.122], p= 0.049). Additionally, increasing invasiveness and occurrence of severe DJK (1.030 [1.007-1.054], p= 0.024) and revision (1.026 [1.008 - 1.044], p=0.005). Invasiveness increased with deformity and frailty severity: 53.6 Low-Mod/N-SF, 81.4 Sev/N-SF, 56.4 Low-Mod/SF, 79.8 Sev/SF; p=0.002. After defining a favorable outcome as no occurrence of severe DJK, no major complications and no revisions, and 1Y mJOA improvement (28.1%), invasiveness scores were compared within deformity/frailty groups between patients who met/did not meet the favorable outcome. For the NSF deformity groups, those with a favorable outcome had larger invasiveness scores (Low-Mod: 58.7 vs 48.5; Sev: 77.7 vs 89.6). For the SF deformity groups, the favorable outcome had significantly lower invasiveness scores for the Low-Mod deformity group (38.1 vs 62.9, p=0.008), while the Sev/SF deformity favorable outcome group remained larger (86.8 vs 79.4), though this was not significant. For the Low-Mod/SF group an invasiveness cutoff score of <48 where achieving a favorable outcome was 3x higher (3.08[1.2-7.9], p=0.019).
CONCLUSION(S): For SF patients, when deformity severity is low to moderate, surgeons may limit the invasiveness of their procedures in order to account for the patient's susceptibility to poor outcomes. FDA DEVICE/DRUG STATUS: This abstract does not discuss or include any applicable devices or drugs.
Copyright

BACKGROUND CONTEXT: AI algorithms have shown substantial promise in medical image analysis. Previous studies of ASD clusters have analyzed alignment metrics - this study sought to complement these efforts by analyzing images of anatomical landmarks. PURPOSE: We hypothesized that a neural-network-based artificial intelligence (AI) algorithm would cluster preoperative lateral radiographs of into groups with distinct morphology. STUDY DESIGN/SETTING: Retrospective cohort study. PATIENT SAMPLE: A total of 915 patients with adult spinal deformity and preoperative lateral radiographs. OUTCOME MEASURES: Schwab modifiers for SVA and PI-LL, three-column osteotomy, upper instrumented vertebrae, baseline Oswestry Disability Index, and 2-year likelihood of reaching MCID in ODI (set at -12.8). Proximal junctional kyphosis and proximal junctional failure were defined using previously published radiographic criteria.
METHOD(S): Vertebral locations for C3-L5, sacral endplate, and femoral heads were measured on lateral radiographs. Pixel locations were used to create a black-and-white overlay to the image, which was subsequently standardized for size and position using the femoral heads and sacral endplate. These images were used to train a self-organizing map (SOM). SOMs are a form of artificial neural network frequently employed in unsupervised classification tasks.
RESULT(S): In total, 915 preoperative lateral radiographs were analyzed. A 2 x 3, toroidal SOM was trained. The mean spine shape was plotted for each cluster. Alignment, surgical characteristics, and outcomes were compared between clusters. Clusters C and D exhibited a particularly high proportion of patients with optimal (ie, modifier 0) values of PI-LL (65.0% and 68.5%) and SVA (72.8% and 53.1%). Conversely, clusters B, E, and F tended to have poor (ie, modifier ++) PI-LL (74.8%, 66.9%, and 74.6%) and SVA (75.5%, 48.6%, and 58.7%). 3-CO was most common among cluster A (26.8%), cluster B (32.6%), and cluster F (32.7%). UIV at T7-T12 was most common among cluster B (51.1%) and cluster F (60.3%). ODI <30 was most prevalent among cluster D (31.4%). There was little difference, however, between groups in likelihood of reaching MCID in ODI at 2-year follow-up. PJK and PJF were particularly prevalent among clusters A (51.2% and 15.5%) and E (50.4% and 18.7%).
CONCLUSION(S): This study developed a self-organizing map that clustered preoperative lateral radiographs of ASD patients into groups with highly distinct overall spinal morphology. These clusters predicted alignment, surgical characteristics, and HRQOL. Further studies of this classification approach will expand to compare pre- and postoperative radiographs. FDA DEVICE/DRUG STATUS: This abstract does not discuss or include any applicable devices or drugs.
Copyright

BACKGROUND CONTEXT: Hyperlordotic (>20degree) anterior interbody cages (HAI) may be utilized in anterior-posterior fusion (AP-F) in efforts to improve alignment. However, significant increase in segmental lordosis (SL) in HAI without superior articulating process resection (SAP) may result in foraminal stenosis and nerve root compression causing neurological deficits and radiculopathy. Additionally, HAI with SAP may increase SL without concomitant increase in lumbar lordosis (LL). PURPOSE: Assess whether HAI without SAP in APF causes increased neurological complications. STUDY DESIGN/SETTING: Single-center retrospective cohort study PATIENT SAMPLE: A total of 158 patients undergoing single level APF were included, of which 73 had HAI placed and 85 had SAI placed. OUTCOME MEASURES: Outcomes measures included radiographic analysis of pre- and postoperative LL and SL. Perioperative neurological complications were measured including new radiculopathy, iatrogenic motor deficit and malpositioned instrumentation or compressive hematoma causing deficit. Returns to OR within 30 or 90 days were measured including return for foraminal decompression, instrumentation revision, hematoma evacuation, and irrigation and debridement.
METHOD(S): Patients undergoing primary, single level, APF without SAP resection over a 5-year period were included. Patients were classified as HAI or SAI. Outcomes measures included perioperative neurological complications, returns to OR, pre- and postoperative LL and SL. Demographic, procedural and perioperative outcomes were compared using independent samples t-tests and chi-squared analyses as appropriate with significance set at p<0.05. Risk factors for development of neurological complications were assessed with multivariate logistic regression.
RESULT(S): A total of 158 patients (73 HAI, 85 SAI) were included. Age, gender, BMI and CCI were similar between groups. HAI without SAP resulted in significantly larger change in SL (9.84+/-5.84 vs 7.32+/-5.02 deg, p=0.001), without a significantly larger change in LL (8.16+/-1.11 vs 11.5+/-1.69 deg; p=0.641) compared with SAI. HAI without SAP increased overall incidence of neurological deficit (13.69% vs 3.53%; p=0.012), iatrogenic new cases of radiculopathy (10.95% vs 3.53%; p=0.045), and iatrogenic neurological motor deficit (13.69% vs 3.53%; p=0.012). Regression analysis demonstrated that increasing cage lordosis greater than 20degree is an independent risk factor for neurological complications (p=0.046), as is higher preop SL (p=0.022). There were no significant differences in returns to OR.
CONCLUSION(S): We caution HAI implantation without SAP resection due to increased neurological complications from iatrogenic nerve root injury without the benefit of significantly improving LL correction. Use of HAI without SAP resection in single level APF should not be standard practice due to risk of neurological complications. FDA DEVICE/DRUG STATUS: This abstract does not discuss or include any applicable devices or drugs.
Copyright