Faculty Bibliography

The aim of this study was to investigate the cost utility of treating non-frail versus frail or severely frail adult spinal deformity (ASD) patients. 79 surgical ASD patients >18 years with available frailty and ODI data at baseline and 2-years post-surgery (2Y) were included. Utility data was calculated using the ODI converted to the SF-6D. QALYs utilized a 3% discount rate to account for decline to life expectancy (LE). Costs were calculated using the PearlDiver database. ICER was compared between non-operative (non-op.) and operative (op.) NF and F/SF patients at 2Y and LE. When compared to non-operative ASD, the ICER was $447,943.96 vs. $313,211.01 for NF and F/SF at 2Y, and $68,311.35 vs. $47,764.61 for NF and F/SF at LE. Frail and severely frail patients had lower cost per QALY compared to not frail patients at 2Y and life expectancy, and had lower ICER values when compared to a non-operative cohort of ASD patients. While these results support operative correction of frail and severely frail patients, it is important to note that these patients are often at worse baseline disability, which is closely related to frailty scores, and have more opportunity to improve postoperatively. Furthermore, there may be a threshold of frailty that is not operable due to the risk of severe complications that is not captured by this analysis. While future research should investigate economic outcomes at extended follow up times, these findings support the cost effectiveness of ASD surgery at all frailty states.

INTRODUCTION/BACKGROUND:Outcomes after anterior cervical diskectomy and fusion (ACDF) and cervical total disk arthroplasty (TDA) are satisfactory, but related morbidity and revision surgery rates are notable. This study sought to determine complication variations among ACDF, TDA, and combined ACDF-TDA as well as predictors of postoperative complications. METHODS:Patients undergoing 1- to 2-level ACDF and/or TDA with at least a 2-year follow-up from 2009 to 2011 were identified from the Statewide Planning and Research Cooperative System database. Patient demographics, hospital-related parameters, mortality, and postoperative outcomes were compared, and their predictors were identified using multivariate logistic regression. RESULTS:A total of 16,510 and 449 individuals underwent ACDF and cervical TDA, respectively, and 201 underwent ACDF-TDA. ACDF-TDA patients had the highest rates of cardiac complications and pulmonary embolism (PE) (P ≤ 0.006), whereas TDA patients had higher individual surgical and device/implant/internal fixation complications (P ≤ 0.025). ACDF-TDA patients experienced the lowest rate of revisions. Cervical TDA increased the odds of any surgical complications (OR = 2.5, P = 0.002), overall complications (OR = 1.57, P = 0.034), and revisions (OR = 2.29, P < 0.001). Deyo index predicted any medical/surgical complications (OR = 1.43 and 1.19, respectively). Female sex was associated with increased odds of readmission (OR 1.30, P < 0.001) but was protective against medical complications (OR = 0.81, P = 0.013). DISCUSSION/CONCLUSIONS:Combined ACDF-TDA procedures were not associated with increases in 2-year individual or overall complications, readmissions, or revisions. LEVEL OF EVIDENCE/METHODS:Level 3-Therapeutic study.

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: Neurologic complications following adult spinal deformity (ASD) are common and may play a role in the outcomes for our patients. Neurologic complications may include radiculopathy, sensory deficit or motor weakness. The impact that these specific complications have on HRQL is unknown. PURPOSE: Neurologic complications are common following ASD. Understanding their impact on Health-related quality of life (HRQL) measures is critical. STUDY DESIGN/SETTING: Retrospective cohort study of prospective ASD database. PATIENT SAMPLE: Retrospective cohort study, 733 patients. OUTCOME MEASURES: Neurologic complications, HRQL scores.
METHOD(S): ASD patients (>18yrs, scoliosis >=20degree, SVA >=5cm, PT >=25degree and/or TK >60degree). Inclusion criteria was HRQL at baseline (BL) and 1 year, and lower extremity motor score (LEMS) at BL, 6-week and 1-year ODI, SRS22r and SF36 were determined at BL and 1yr LEMS was calculated from 0-50, with 50 designated as normal motor function. Patients were divided into 4 groups: pLEMS (perfect, no deficit), dLEMS (new postop deficit that returned to normal at 1 year), iLEMS (deficit improved from abnormal baseline), and wLEMS (new postop deficit persistent at one year).
RESULT(S): A total of 733 patients were eligible, with 95 (12.96%) reporting neurologic complications (NC). Impact of any NC vs no complication at 1yr was significant for ODI (5.1), PCS (3.6) and SRSpain (0.2) at 1 year (p<0.001 all). For NC vs any other complication, there was still a decrease in ODI (3.9) and PCS (2.4) at 1 year (p<0.01). NC subtype: radiculopathy caused worse outcomes for (4.3) and SRS pain (0.3) (p<0.05), sensory deficit caused worse SRSmental (0.5) (p<0.05), but no HRQL change was detected for motor deficit at 1 year. PLEMS (456/733) had improvement in all HRQL, and these improvements were not different with or w/o NC, or non-NC. Compared to pLEMS w/o complication, dLEMS (62/733) and iLEMS (147/733) were statically similar, however wLEMS (68/733) had worse ODI (7.1), SRStotal (0.3), activity (0.3), mental (0.3), pain (0.3) (p<0.05 all).
CONCLUSION(S): Neurologic complications that occur following ASD have a significant effect on HRQLs. The magnitude of effect is driven by radiculopathy and by lower extremity motor score. LEMS scores that remain normal, return back to normal or improve have similar outcomes, while patients that have continued weakness remain statistically worse at 1 year. FDA DEVICE/DRUG STATUS: This abstract does not discuss or include any applicable devices or drugs.
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BACKGROUND CONTEXT: For patients with coronary artery disease, the two most common options for intervention are a cardiac stent or a coronary artery bypass graft. Although less invasive, stents may pose a long-term risk for patients undergoing further invasive procedures such as elective spine surgery. This study aimed to provide surgeons with insight on possible major complications for elective spine surgery patients with a history of coronary artery disease. PURPOSE: Investigate outcomes of elective spine fusion patients with prior history of cardiac intervention STUDY DESIGN/SETTING: Retrospective review of the PearlDiver database between the years 2006-2013 PATIENT SAMPLE: A total of 731,173 elective spine fusion patients OUTCOME MEASURES: Comorbidity burden, 30-day and 90-day complications, readmission METHODS: Elective spine fusion patients were isolated with ICD-9 and CPT procedures codes in the PearlDiver database. Patients were stratified by having previous history of a coronary stent (Stent), coronary artery bypass graft (CABG), and no previous heart procedure (No-HP). Means comparison tests (chi-squared and independent samples t-tests, as appropriate) compared differences in demographics, diagnoses, and comorbidities. Logistic regression assessed the odds of 30-day and 90-day postoperative (postop) complications associated with each heart procedure (Odds Ratio [95% confidence interval]). Statistical significance was set p<0.05.
RESULT(S): A total of 731,173 elective spine fusion patients were included. Overall, 8,401 pts underwent a CABG, 24,037 patients Stent, and 698,735 had No-HP prior to spine fusion surgery. Compared to Stent and No-HP patients, CABG patients had higher rates of morbid obesity, chronic kidney disease and diabetes (p<0.001 for all). Stent patients had higher rates of peripheral vascular disease, hypertension, and hyperlipidemia (all p<0.001). Within 30 days postoperatively of index surgery, CABG patients had significantly higher complication rates including pneumonia, cerebrovascular accident (CVA), myocardial infarction (MI), sepsis, and death compared to No-HP (all p<0.001). Stent patients vs No-HF also had higher 30-day postoperative complication rates including pneumonia, CVA, MI, sepsis, and death. Adjusting for age, comorbidities and sex, Stent was significantly predictive of a MI 30-days post-op (OR: 1.90 [1.53-2.34], P<0.001). Additionally, Stent patients compared to CABG patients had 1.99x greater odds of a MI within 30-days (OR: 1.99 [1.26-3.31], p=0.005) and 2.02x greater odds of readmission within 90-days postop (OR: 2.2 [1.53-2.71, p<0.001).
CONCLUSION(S): With regards to spine surgery, coronary artery bypass graft remains the gold standard for risk reduction. Stenting does not appear to minimize risk as significantly as CABG. When assessing patients with a history of coronary artery disease for elective spine fusion surgery, surgeons should be cautious of the significant risk of major complications associated with stents compared to coronary artery bypass grafting. FDA DEVICE/DRUG STATUS: This abstract does not discuss or include any applicable devices or drugs.
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BACKGROUND CONTEXT: The Miller et al. adult spinal deformity frailty index (ASD-FI) correlates with increased complication risk after surgery; however, its development is rooted in health related quality of life metrics (HRQLs) that may be subjective, and the 40 factors needed for its calculation limit the index's utility in a clinical setting. PURPOSE: Develop a simplified, modified frailty index for ASD patients STUDY DESIGN/SETTING: Retrospective cohort study PATIENT SAMPLE: A total of 531 ASD patients OUTCOME MEASURES: HRQLs, length of stay (LOS) METHODS: ASD patients (scoliosis>=20degree, SVA>=5cm, PT>=25degree, or TK >=60degree) with baseline (BL) and 2-year HRQL follow up. HRQL components were removed from the FI and top contributors to the ASD-FI score of the remaining were assessed via Pearson correlation, and included in forward multiple stepwise regressions. Factors with the largest R2 value were including in the modified, ASD-FI (clin-ASD-FI). Factors included in the clin-ASD-FI were regressed against mortality, extended length of hospital stay (>8 days), revisions, major complications and weights for the clin-ASD-FI were calculated via Beta/Sullivan. Total clin-ASD-FI score was created with a score from 0 to 1. Linear regression correlated the clin-ASD-FI with ASD-FI scores and published cut-offs for the ASD-FI were used to create the new frailty cutoffs: not frail (NF: < 0.11), frail (F: 0.11-0.21) and severely frail (SF: >0.21). Binary logistic regression assessed odds of complication or reop for frail patients. Logistic regressions were run to determine whether the clin-ASD-FI is superior to previously utilized measures predicting risk (age, ASA, previous FI, and CCI) for complications and reop.
RESULT(S): A total of 531 ASD patients (59.5yrs, 79.5%F). The final stepwise regression model R2 of 0.681: <18.5 or >20 BMI (weight: 0.0625 out of 1), cardiac disease (0.125), disability employment status (0.3125), diabetes mellitus (0.0625), hypertension (0.0625), osteoporosis (0.125), blood clot (0.1875), and bowel incontinence (0.0625). These factors calculated the score from 0 to 1, with a mean cohort score of 0.13+/-0.14. Breakdown by clin-ASD-FI score: 51.8% NF, 28.1% F, 20.2% SF. Increasing frailty severity was associated with longer LOS (NF: 7.0, F: 8.3, SF: 9.2 days; p<0.001). When assessing BL HRQL status between the new clin-ASD-FI groups, ODI, EQ5D, SRS, PCS, MCS, NRS-Back, and NRS-Neck were worse with increasing categorical frailty (all p<0.001). Frailty independently predicted occurrence of any complication (9.357[2.20-39.76], p=0.002) and reop (2.79[0.662-11.72], p=0.162). Specific complications predicted included infection, neurologic, operative, radiographic, and wound complications (OR: 1.69-5, all p<0.001). Chi-square and p-values for the historical risk predictors of complications are as follows: Age(complication: 1.01[1-1.03] p=0.052; reop: 0.999[0.984-1.01] p=0.866), ASA(complication: 1.102[1.20-2.18], p=0.002; reop: 1.31[0.927-1.84], p=0.177), previous frailty index(complication: 8.57[1.66-44.17], p=0.010; reop=2.629[0.498-16.06], p=0.241), CCI(complication: 1.24[1.10-1.40], p<0.001; reop: 1.06[0.943-1.20], p=0.320).
CONCLUSION(S): Utilizing an existing ASD frailty index, we proposed a modified version eliminating the patient-reported components. This index is a true assessment of physiologic status, and represents a superior risk factor to other risk assessment tools for baseline and revision spinal deformity surgery as a result of its immutability with surgery, lack of subjectivity, and ease of use. Future studies should explore external validation of the proposed frailty index. FDA DEVICE/DRUG STATUS: This abstract does not discuss or include any applicable devices or drugs.
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BACKGROUND CONTEXT: Metabolic (Met) syndrome is an amalgamation of medical disorders that ultimately increase patient complications. Factors such as obesity, hypertension, dyslipidemia and hyperglycemic are associated with this disease complex (two or more factors). PURPOSE: Assess the incremental value of improving Met syndrome in relation to clinical outcomes. STUDY DESIGN/SETTING: Retrospective cohort study of patients with metabolic syndrome through the use of the Nationwide Inpatient Sample (NIS) years 2007-16. PATIENT SAMPLE: Elective spine surgery patients with >2 metabolic syndrome criteria. OUTCOME MEASURES: Complications.
METHOD(S): Pts undergoing elective spine surgery were isolated in NIS 2007-2016. Spine patients were then separated into two groups: metabolic syndrome patients (>2 metabolic variables: hypertension, diabetes, obesity, and triglycerides) and non-metabolic patients (<2 metabolic variables). T-tests and chi-squared tests compared differences in pts demographics. Resolution of metabolic factors were incrementally analyzed for their effect on perioperative complications through utilization of logistic regressions.
RESULT(S): A total of 2,855,517 elective spine pts were included and 20.1% had metabolic syndrome (81.4% 2 factors, 18.4% 3 factors, 0.2% 4 factors). Met pts were older, less female, and more comorbid (p<0.001). Among the metabolic patients, the most common metabolic variable was hypertension (95.9%), blood sugar (72.4%), obesity (48.9%), and triglycerides/HDL (1.8%). A total of 28.8% Met pts developed more complications such as anemia (9.8% vs 5.9%), device-related (3.5% vs 2.9%), neurologic (2.3% vs 1.4%), and bowel issues (9.7% vs 6.8%; p<0.05). Controlling for age and invasiveness, having 3 Met factors increased a PT's likelihood (0.89x) of developing a perioperative complication (p<0.05) whereas 2 factors had lower odds (0.82). More specifically, pts that were hyperglycemic, obese, and had hypertension had the greatest odds at developing a complication (0.58 [0.58-0.57]) followed by those that had concomitant hypertension, high triglycerides, and were obese (0.55[0.63-0.48]; all p<0.001). Met pts with 2 factors, being obese and having hypertension produced the lowest odds at developing a complication (0.5[0.61-0.43;p<0.001). These Met pts also had a lower length of stay than those with 3 and 4 (p<0.001).
CONCLUSION(S): Metabolic patients improved in perioperative complications incrementally, demonstrating the utility of efforts to mitigate burden of metabolic syndrome even if not completed abolished. 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: Chiari malformations (CM) are congenital or acquired hind brain anomalies with resultant cerebellar tonsillar herniation through the foramen magnum. Chiari I malformation consists of herniation of the cerebellar tonsils into the foramen magnum thus crowding the craniocervcial junction. Surgical management is variable among these type 1 patients(pts) based on their presenting symptoms. PURPOSE: Identify complication rates following CM surgery. STUDY DESIGN/SETTING: Retrospective cohort study of (Kids' Inpatient Database) KID. PATIENT SAMPLE: Chiari Malformation Type I. OUTCOME MEASURES: Complication rates, fusion, decompression, duroplasty, laminectomy, LOS, Readmission.
METHOD(S): The KID database was queried for diagnoses of operative Chiari Malformation from 2003-2012 by ICD-9 codes (348.4). Differences in preoperative demographics (age/BMI) and perioperative complication rates between patient cohorts were assessed using Pearson's chi-squared tests and T-tests when necessary. Binary logistic regression were utilized to find significant factors associated with complication rate. Decision tree analysis was utilized for continuous variables predictive of complication rate. Certain surgical procedures were analyzed for their relationship with post-operative outcomes.
RESULT(S): A total of 13,812 CM-1 patients were isolated (10.12 yrs, 0.62 CCI). Of these pts, 8.2% (1,128) received a complication. From 2003 to 2012, the rate of complications for CM-1 pts decreased significantly (9.6%-5.1%) along with surgical rate (33.3%-28.6%), despite the increase in CM diagnosis (36.3%-42.3%; all p<0.05). CM-1 pts who had a complication were younger (9.73+/-6.8 yrs vs 10.2+/-6.3 yrs) and had a lower invasiveness score (0.35+/-1.0 vs 0.41+/-1.0), however; they had a larger CCI (1.10+/-1.6 vs 0.6+/-1.3) than those who did not have a complication (all p<0.05). The most prevalent comorbidities for these pts were cerebrovascular (16.67%), malignancy (11.6%), pulmonary (9.6%), and renal (7.1%; all p<0.05). CM-1 pts who experienced complications had a concurrent diagnosis of syringomyelia (7.1%) and also Scoliosis (3.2%; all p<0.05). CM-1 pts who did not have a complication had a greater surgical rate than those that had a complication (76.4% vs 23.6% p<0.05). Having an interbody instrument, having an invasiveness score>4.25 and receiving a fusion greater than 4 levels were all significant factors associated with receiving a complication postoperatively (p<0.05). The most common complication was nervous system related (2.8%), anemia (2.4%), and acute respiratory distress (2.1%). CM-1 pts that underwent a fusion (3.4% vs 2.1%) had greater complication rates as well as those that underwent a craniotomy (23.2% vs 19.1%; all p<0.05). However, CM-1 pts who underwent a decompression had lower postop complications (21.3% vs 28.9%; all p<0.05). A total of 13,812 CM-1 patients isolated (10.12 yrs, 0.62 CCI). Of these pts, 8.2% (1,128) received a complication. From 2003 to 2012, the rate of complications for CM-1 pts decreased significantly (9.6%-5.1%) along with surgical rate (33.3%-28.6%), despite the increase in CM diagnosis (36.3%-42.3%; all p<0.05). CM-1 pts who had a complication were younger (9.73+/-6.8yrs vs 10.2+/-6.3yrs) and had a lower invasiveness score (0.35+/-1.0 vs 0.41+/-1.0), however; they had a larger CCI (1.10+/-1.6 vs 0.6+/-1.3) than those who did not have a complication (all p<0.05). The most prevalent comorbidities for these pts were cerebrovascular (16.67%), malignancy (11.6%), pulmonary (9.6%), and renal (7.1%; all p<0.05). CM-1 pts who experienced complications had a concurrent diagnosis of syringomyelia (7.1%) and also Scoliosis (3.2%; all p<0.05). CM-1 pts who did not have a complication had a greater surgical rate than those that had a complication (76.4% vs 23.6% p<0.05). Having an interbody instrument, having an invasiveness score>4.25 and receiving a fusion greater than 4 levels were all significant factors associated with receiving a complication postoperatively (p<0.05). The most common complication was nervous system related (2.8%), anemia (2.4%), and acute respiratory distress (2.1%). CM-1 pts that underwent a fusion (3.4% vs 2.1%) had greater complication rates as well as those that underwent a craniotomy (23.2% vs 19.1%; all p<0.05). However, CM-1 pts that underwent a decompression had lower postop complications (21.3% vs 28.9%; all p<0.05).
CONCLUSION(S): Treatment of Chiari malformation has been identified to have improved from 2003 to 2012 with increased identification of diagnosis and decreased complications. Chiari patients undergoing fusions and craniotomies are at a greater risk of postoperative complications especially when the instrumented fusions are performed on >4 levels. 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) surgery is complex and may lead to new-onset cervical malalignment and/or proximal junctional kyphosis (PJK). Roussouly et al describes variations in baseline thoracolumbar (TL) shape (Types 1-4), which have been shown to differentially influence surgical ASD outcomes. The effect of morphological shape on patterns of postoperative CD development remains underexplored. PURPOSE: Stratify patients by Roussouly type and assess patterns of conversion from baseline (BL) cervical alignment to postoperative cervical deformity (CD) in patients undergoing thoracolumbar ASD surgery. STUDY DESIGN/SETTING: Retrospective review of a prospective multicenter database of ASD patients. PATIENT SAMPLE: A total of 266 surgical ASD patients. OUTCOME MEASURES: Rate and timing of conversion to CD, rate of PJK, radiographic alignment parameters.
METHOD(S): Operative ASD patients with complete radiographic data at baseline, 6W, 1Y, 2Y, & 3Y intervals were included. Patients were grouped by baseline PI and apex of LL into component types of the Roussouly classification system utilizing pelvic incidence as published by Pizones et al. Patients with no BL CD were postoperatively stratified by Ames CD criteria (TS-CL>20 degree, cSVA>40mm), where CD was defined as fulfilling >1 criteria. Follow-up intervals were established post-ASD surgery, with 6W postop defined as "Early," 6W-1Y "Intermediate," 1-2Y "Late," and 2-3Y "Long." Univariate and Cox regression analyses identified CD conversion rate and PJK rate (<-10degree change in UIV and UIV+2) across Roussouly types 1-4.
RESULT(S): A total of 266 surgical ASD patients (59.7yrs, 77.4% F) with complete radiographic data were included. By Roussouly classification, 9% were Type 1, 15.8% Type 2, 46.6% Type 3, and 28.6% Type 4. 28.6% of ASD patients converted to postop CD (Early: 14.3%, Intermediate: 5.3%, Late: 4.1%, Long: 4.9%). There were no significant differences in CD conversion rate across Roussouly types (1: 33.3%; 2: 28.6%; 3: 26.6%; 4: 30.3%, P=0.895). Types 2 (41.7%), 3 (60.6%), and 4 (43.5%) had their peak rates of conversion in the Early (<6w) window compared to other follow-up intervals, whereas Type 1 patients had a peak rate (50%) between 6w-1Y. Type 2 patients had higher rates of later CD conversion (>1 year) than other types (50% vs 28.1%, P=0.135), while Type 1 patients trended higher rates of earlier CD conversion (<1 year) than other types (33.8% vs 12.5%, P=0.220); these patterns did not reach statistical significance. Across Roussouly Types, among patients who converted to CD, Type 4 had significantly higher rates of ++ SRS-Schwab PT and greater TPA at BL (both p<0.05). Type 4 patients had the highest rate of concurrent PJK with CD conversion (60.9%) compared to Type 1 (50%), Type 2 (50%), or Type 3 (54.5%) (P>0.05). There were no significant change in ODI, PCS, or SRS total among Roussouly Types in patients that converted to CD (p>0.05). Random forest analysis determined the top surgical (levels fused), radiographic (TS-CL), and demographic (frailty) factors associated with CD conversion.
CONCLUSION(S): Baseline thoracolumbar shape as described by the Roussouly classification has a differential effect on timing to CD conversion, though overall rates of CD conversion after TL-ASD correction were similar across Types 1-4. Type 1 patients with a lower apex of lumbar lordosis trended earlier conversion, while Type 2 patients with a higher apex of LL trended conversion beyond 1-year postop. FDA DEVICE/DRUG STATUS: This abstract does not discuss or include any applicable devices or drugs.
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