Faculty Bibliography

BACKGROUND CONTEXT: C5 palsy stands as a known but poorly understood complication of cervical spine surgery with rates reported as high as 30%. Although there are multiple studies presenting different risk factors, variability in findings have led to controversy in the etiology of postoperative C5 palsy. PURPOSE: To evaluate factors that predispose a patient to developing C5 palsy following cervical spine surgery. STUDY DESIGN/SETTING: Retrospective review of a large single center academic institution. PATIENT SAMPLE: This study included 239 cervical spinal procedures from 2013 to 2018. OUTCOME MEASURES: Patient demographics, surgical procedure and approach, perioperative clinical characteristics, postoperative rate of C5 palsy, C5 palsy resolution, and radiographic outcomes.
METHOD(S): Patients >=18 years of age who underwent cervical spinal surgery including the C4/C5 level, with minimum 1-year follow-up were included. C5 palsy was defined as deltoid +/- bicep weakness with Modified Rankin Scale grading at least 1 point below baseline (BL). Characteristics studied include: demographics, surgical procedure and approach (decompression and/or fusion). Radiographic analyses of MRI and CT measurements of foramen dimensions and spinal cord drift at BL and follow-up were performed. Statistical analyses included t-tests, chi-square analysis, and multivariate logistic regression to determine independent predictive factors. A receiver operating characteristic curve was run to determine the cutoff levels for predictive factors. Significance set at p<0.05.
RESULT(S): A total of 239 patients were included, with a C5 palsy rate of 6.3% for all cases. Subjects that developed C5 palsy were older (64.67+/-8.61 vs 57.56+/-11.61, p=0.021), had more levels decompressed posteriorly (3.20+/-1.82 vs 1.12+/-1.74, p<0.001), a higher rate of preoperative myelomalacia (60% vs 19.6%, p=0.008), and higher CCI (3.80+/-1.97 vs 2.35+/-1.95, p=0.005). Anterior cervical discectomy and fusion (ACDF) surgeries had a 2.4% rate of C5 palsy while the posterior approach rate was 11.9% (p<0.007). The highest rate was in laminectomy and posterior fusion at 15.2% (p<0.001). There were no significant differences in palsy resolution between those treated surgically compared to those not treated. Radiographically, C5 palsy patients had smaller postoperative foramen width measurements than those who did not develop C5 palsy (2.16+/-1.04 vs 3.31+/-1.25, p=0.023 on the right; 1.84+/-0.80 vs 3.02+/-1.25, p=0.014 on the left). When controlling for technique, CCI, age, BMI, and myelomalacia, multivariate regression analysis revealed increasing levels of laminectomy to be a significant independent predictor of C5 palsy (1.602 (2.258-1.136) for each additional level decompressed, p=0.007). The cut-off value for levels decompressed via laminectomy was determined to be 3.50 levels (>=0.7 AUC <=0.8). Postoperative foramen width was also an independent risk factor for C5 palsy (0.009 (0.000-0.726), p=0.035), it was determined that risk of C5 palsy increases at <2.625mm foramen width (>=0.8 AUC <=0.9).
CONCLUSION(S): C5 palsy following cervical spine surgery is correlated with residual postoperative foraminal stenosis and posterior surgery with increasing number levels decompressed. Patients undergoing more than 3.5 level laminectomy with less than 2.625mm foramen width postoperatively are at highest risk of developing C5 palsy. 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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BACKGROUND CONTEXT: The Adult Spinal Deformity Frailty Index (ASD-FI), a validated modality for quantifying frailty, stratifies patients into categories not frail (NF), frail (F) and severely frail (SF). However, the cost of treating each frailty state is unknown. PURPOSE: Investigate the cost utility of treating not frail versus frail or severely frail ASD patients. STUDY DESIGN/SETTING: Retrospective review of a prospective single center adult spinal deformity database. PATIENT SAMPLE: A total of 79 operative and non operative ASD patients >=18 years old, with baseline and 2Y ASD-FI and Oswestry Disability Index (ODI) scores. OUTCOME MEASURES: ODI, SF-6D, Cost per quality adjusted life years (QALY), Incremental Cost Effectiveness, Ratio (ICER).
METHOD(S): Inclusion criteria was surgical ASD (scoliosis>=20degree, SVA>=5cm, PT>=25degree, or thoracic kyphosis >=60degree) patients >18 years with available frailty and ODI data at BL and 2-years post op. Independent T-Tests assessed baseline radiographic differences in PT, PI-LL, and Schwab SVA modifier status between NF vs. F/SF patients. Utility data was calculated using the ODI converted to the SF-6D using published conversion methods. QALYs utilized a 3% discount rate to account for residual decline to life expectancy (78.7 years). Costs were calculated using the PearlDiver database. After accounting for complications, LOS, revisions, and death, cost per QALY at 2Y and life expectancy were calculated for NF, and F/SF patients. ICER was compared between non op and operative NF and F/SF patients at 2Y and life expectancy.
RESULT(S): Seventy-nine ASD patients met inclusion criteria. Descriptive statistics for the cohort were: age 51.0+/-6.8, 76% women, BMI 26.7+/-6.8, 54% osteotomy, 54% decompression, and 11.6+/-4.2 average levels fused. At BL, there were 48 NF, 26 F, and 4 SF pts. The average BL frailty for NF pts was 0.13+/-0.08, 0.39+/-0.06 for F, and 0.59+/-0.08 for SF pts. There were no differences in PT, PI-LL, or severe SVA Schwab modifier grades between NF or F/SF pts (all p>0.05). At 2-year follow up, there was no difference in the average cost of ASD surgery, $91,068.98 for NF patients and $90,888.53 for F/SF pts (p>0.05). The cost per QALY was higher for NF pts at 2 years vs F/SF pts ($464,239.62 vs. $321,107.89, p<0.05). If the utility gained was sustained to life expectancy, the cost per QALY was $70,796.43 for NF and $48,968.88 for F/SF (p<0.05). When compared to non op ASD pts, the ICER was $447,943.96 vs. $313,211.01 for NF and F/SF at 2 years, and $68,311.35 vs. $47,764.61 for NF and F/SF at life expectancy.
CONCLUSION(S): Frail and severely frail patients had lower cost per QALY compared to not frail patients at 3 years and life expectancy. In addition, when compared to a non operative cohort of ASD patients, frail and severely frail patients had lower ICER values. 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. In addition, 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. FDA DEVICE/DRUG STATUS: This abstract does not discuss or include any applicable devices or drugs.
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BACKGROUND CONTEXT: In the current value-based health care climate where spinal surgery is shifting to the ambulatory setting, factors influencing postoperative patient length of stay (LOS) have significance to both surgeons and hospital administrators. Underlying patient factors including the diagnosis of radiculopathy and myelopathy have not been investigated in this context. PURPOSE: Identify predictors extended LOS(E-LOS) between myelopathy(M), radiculopathy(R), and patients with both (MR). STUDY DESIGN/SETTING: Retrospective review of a single-center stereographic database. PATIENT SAMPLE: A total of 718 surgical cervical spine patients. OUTCOME MEASURES: Postoperative LOS, patient factors, preoperative HRQL, complications, predictors of E-LOS.
METHOD(S): Surgical cervical spine patients >=18yrs diagnosed with M or R primary diagnoses were isolated in the single-center Comprehensive Spine Quality Database (Quality). Patients were stratified by surgical approach: Anterior, Posterior or Combined. Top-quartile LOS values were labeled as extended. M and R patients were compared using chi-squared and independent samples t-tests, as appropriate. Univariate tests assessed differences in baseline patient-related and surgical data between M and R, and extended/non-extended LOS. Univariate/multivariate analyses were run to assess predictive factors of E-LOS in each diagnosis group. Regression with stepwise model selection was employed to explore factors potentially significant in predicting LOS.
RESULT(S): A total of 718 patients (54.5 years, 41.1%F, 29.1kg/m2). Mean CCI score: 1.11. Within the cohort, 177 patients (24.7%) had a diagnosis of myelopathy, 383 (53.3%) radiculopathy, and 22% with a diagnosis of myeloradiculopathy. Patients with M primary diagnosis were significantly older (62.2 vs 49.8yrs, p<0.001) and had a greater CCI score (1.64 vs 0.82, p<0.001) when compared to R patients. By approach: 76.7% anterior (57.6% of M, 90.6%R, 64.6%MR; p<0.001), 16.4% (35%M, 6%R, 20.9%MR; p<0.001) posterior, 6.5% (6.8%M, 3.4%R, 13.9%MR; p<0.001) combined. Average LOS: M(3.8days), R(1.5 days), MR(2.9 days) p<0.001. LOS for anterior approach in each diagnosis was as follows, M: 2.21, R: 1.21, MR: 1.69 days, p<0.001. Meanwhile, posterior approach LOS, M:6.06, R:2.91, MR:5.0, p<0.001; combined approach M: 5.17, R: 6.23, MR: 5.59, P=0.881. A total of 195 patients were categorized as E-LOS (Avg: 5.87 days), 87 M, 43 R, 65 MR. Major surgical approach of E-LOS for M (60.9%) and MR (44.6%) was posterior; whereas R E-LOS patients majorly underwent anterior procedures (53.5%). Generalized linear regression modeling found that the following combination of factors predicted E-LOS in R patients (R2=0.736, p=0.003):BMI, durotomy, CCI, anterior and combined approaches, and cardiac complications. An additional model discovered the predictors of E-LOS in M patients (R2= 0.312, p<0.001): age, hypertension, CCI, anterior and combined approaches, intraoperative complications, neuro complications, ileus, and return to OR in 90 days. Lastly, the model for E-LOS in MR patients consisted of (R2 = 0.267, p=0.001): age, durotomy, BL EQ5D, hypertension, posterior and combined approaches and postoperative complications, specifically neuro.
CONCLUSION(S): Independent of surgical approach, 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. The heightened risk in myelopathy patients for extended LOS should be considered when determining admission status for patients undergoing cervical spine surgery. FDA DEVICE/DRUG STATUS: This abstract does not discuss or include any applicable devices or drugs.
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BACKGROUND CONTEXT: The Roussouly Classification system of sagittal spinal shape and the SRS-Schwab adult spinal deformity (ASD) classification system have become important indicators of spine deformity. No prior studies have examined the outcomes of matching both Roussouly type and improving in Schwab modifiers postoperatively. PURPOSE: Evaluate outcomes of matching Roussouly Type and improving in Schwab modifier following ASD surgery. STUDY DESIGN/SETTING: Retrospective review of single-center ASD database. PATIENT SAMPLE: A total of 103 ASD patients. OUTCOME MEASURES: Roussouly types, Schwab modifiers, Health Related Quality of Life scores(HRQLs): Minimal Clinical Important Difference for ODI, EQ5D, VAS Leg &Back Pain.
METHOD(S): Surgical ASD patients (SVA>=5cm, PT>=25degree, or TK >=60degree, >3 levels fused) >=18 years old with available baseline (BL) radiographic data at baseline (BL) and 1-year (1Y) were isolated in the single-center Comprehensive Spine Quality Database (Quality). Patients were grouped by two Roussouly types: (1)"theoretical" Roussouly type(Type 1: PI<45degree, LL apex below L4; Type 2: PI<45degree, LL apex above L4 L4-L5 space; Type 3: 45degree60degree); (2) "current" Roussouly type (1: SS<35degree, LL apex below L4; 2: PI<35degree, LL apex above L4-L5 space; 3: 35degree45degree), as previously published. One year (1Y) matched Roussouly: preoperative mismatched (Between 'actual' and 'theoretical' patients that matched at 1Y. Schwab modifiers at BL were identified: non-, moderate and severe deformity (0, +, ++) for PT, SVA, and PI-LL. Schwab improvement was defined as a decrease in a modifier at one year.
RESULT(S): A total of 103 ASD patients (61.8yrs, 63.1%F, 30kg/m2). By surgical approach, 79.6% posterior, 10.7% combined, 2.9% anterior). Average levels fused: 4.6. BL breakdown of 'current; Roussouly type: 28% Type 1, 25.3% Type 2, 32.0% Type 3, 14.7% Type 4. BL Roussouly mismatch: 65.3%. Breakdown BL Schwab modifiers: PT (0: 8.7%, +: 41.7%, ++: 49.5%), SVA (0: 29.7%, +: 20.3%, ++: 50%), PI-LL mismatch (0: 28.2%, +: 25.2%, ++: 46.6%). At one year, 19.2% of patients matched Roussouly target type, while according to Schwab modifiers, 12.6% improved in SVA, 42.7% in PI-LL, and 45.6% in PT. Patients who both met Roussouly type and improved in a Schwab by the modifiers: 9 PT (8.7%), 8 PI-LL (7.8%), 2 SVA (1.9%). There were 2 patients (1.9%) who met their Roussouly type and improved in all 3 Schwab modifiers. One year (1Y) matched Roussouly patients improved more in HRQLs (MCID for ODI, EQ5D, VAS Leg/Back Pain), when compared to mismatched Roussouly, but was not significant(P>0.05). Match Roussouly and improvement in PT Schwab met MCID for EQ5D significantly more (33.3% vs 10.6%, p=0.050). Matched Roussouly and PI-LL Schwab had more patients meet MCID for all HRQLs, yet none were significant, p>0.05. Matched Roussouly and improvement in SVA Schwab met MCID for ODI significantly more (p=0.024).
CONCLUSION(S): Patients who both matched Roussouly sagittal spinal type and improved in SRS-Schwab modifiers had superior patient-reported outcomes at 1-year. Utilizing both classification systems in surgical decision making can optimize postop patient outcomes. FDA DEVICE/DRUG STATUS: This abstract does not discuss or include any applicable devices or drugs.
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BACKGROUND CONTEXT: Persistent lumbopelvic malalignment following ASD-corrective surgery may impair quality of life and result in persistent pathologic compensation in the lower extremities. Patient-specific age- and BMI-adjusted alignment targets have been proposed to improve alignment outcomes; however, it is unclear whether reaching these postop targets reduces rates of pelvic nonresponse following surgery. PURPOSE: Assess the relationship between pelvic nonresponse to ASD-corrective surgery and persistent lower-extremity compensation. STUDY DESIGN/SETTING: Single center retrospective review. PATIENT SAMPLE: Fifty-eight ASD patients. OUTCOME MEASURES: Sagittal alignment.
METHOD(S): Included: surgical ASD patients with full-spine X-ray imaging at pre- and early postop follow-up (<1Y). Patients were grouped by postop improvement in PT, per SRS-Schwab Classification: those who did not improve (pelvic nonresponders, PNR), and those that did improve (pelvic responders, PR). Groups were propensity score matched for preop PT, and assessed for differences in demographics, surgical factors, and alignment (sagittal spinal and lower extremity) with means comparison tests. Rates of persistent postop lower extremity compensation (defined as no improvement in lower extremity alignment) were compared between groups. Subanalysis assessed the relationship between reaching postop age- and BMI-specific alignment targets and rates of pelvic nonresponse.
RESULT(S): Following propensity score matching, PNR (N=29) and PR (N=29) patients did not differ in age, sex, BMI or preop sagittal spinal alignment (all p>0.05); however, PNR patients presented with less knee flexion (9degree vs 14degree, p=0.043). Groups did not differ in levels fused (10.8 vs 10.8, p=0.974) or osteotomy (93% vs 92%, p=0.902). Postop, PNR patients had inferior lumbopelvic alignment in PT (30degree vs 17degree), PI-LL (17degree vs 3degree), and greater global malalignment for TPA (27degree vs 15degree, all p<0.001). For PNR patients, these changes in alignment were accompanied by greater compensatory anterior hip extension (53mm vs 31mm, p=0.021). PNR patients also showed greater pre- to postop increases in sacrofemoral angle (2degree vs -5degree), and smaller decreases in hip extension (-24mm vs -64mm), pelvic femoral angle (-1.4degree vs -3.8degree), and global sagittal angle (-3.5degree vs -8degree, all p<0.005), indicating persistent lower extremity compensation. PNR patients had higher rates of persistent postop lower extremity compensation for sacrofemoral angle (68% vs 25%), ankle flexion (64% vs 33%), and pelvic shift (28% vs 4%, all p<0.034). PNR and PR groups did not differ in rates of reaching age- and BMI specific ideal postop alignment for PT, SVA, TPA, or PI-LL (all p>0.05). For patients with severe preop SVA deformity, overcorrection relative to ideal postop PT targets was associated with lower rates of pelvic non-response (under: 12%, match: 18%, over: 71%, p<0.001). Lower rates of nonresponse were observed for patients with severe preop PT deformity overcorrected relative to ideal postop PI-LL (under: 0%, match: 30%, over: 70%, p=0.016).
CONCLUSION(S): Pelvic nonresponders following ASD-corrective surgery had higher rates of persistent compensatory action in the lower extremities. Patients with severe preop PT deformity who were surgically overcorrected with respect to ideal PI-LL had lower rates of postop pelvic nonresponse, indicating that for severely malalignmed patients, existing alignment targets may need to be adjusted to optimize alignment outcomes. FDA DEVICE/DRUG STATUS: This abstract does not discuss or include any applicable devices or drugs.
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