Faculty Bibliography

BACKGROUND CONTEXT: Few guidelines exist regarding appropriate upper instrumented vertebra (UIV) selection for adult spinal deformity (ASD) patients undergoing long fusion to the pelvis. Fusion to upper thoracic (UT) spine may provide greater deformity correction and reduce proximal junctional failure (PJF) rates compared to fusions terminating at the thoracolumbar (TL) spine. Previous reports comparing outcomes for UT vs TL UIV for ASD surgery are confounded by discrepant patient cohorts. PSM analyses can be used to reduce selection bias and mimic patient randomization. PURPOSE: Use a propensity score matched (PSM) analysis to compare surgical and hospital data, deformity correction, complication rates, and patient reported outcomes (PROs) for demographically and radiographically matched ASD patients receiving TL vs UT UIV. STUDY DESIGN/SETTING: PSM analysis of ASD patients prospectively enrolled into a multicenter study. PATIENT SAMPLE: Surgically treated ASD patients. OUTCOME MEASURES: Numeric rating scale (NRS) back and leg pain, Scoliosis Research Society-22r questionnaire (SRS-22r), Short Form-36v2 questionnaire (SF-36), Oswestry Disability Index (ODI), estimated blood loss, duration of hospital stay, postoperative complications, revision spine surgery, PJF.
Method(s): ASD patients prospectively enrolled into a multicenter study from 2009-2018 were classified according to SRS-Schwab ASD Types. Study inclusion; 1) surgery for lumbar (L), sagittal (S) or mixed (M) deformities, 2) fusion to pelvis, 3) >=5 levels fused, 4) >=2 year follow up. Study exclusion; double major or thoracic scoliosis, thoracic hyperkyphosis (>70degree). UIV cohorts formed based on bimodal UIV distribution (TL=L2-T8 vs UT=T6-T1). PSM matched TL and UT for preop demographics, scoliosis, PI-LL, TK, SVA, TPA and osteotomies. Postop deformity correction, complications, and PROs were compared for UT vs TL in L, M, S deformities.
Result(s): Of 699 eligible patients, 417 (L [n=70], S [n=166] and M [n=198]) were evaluated. UT and TL had similar preop age, frailty, spine deformity, follow up, osteotomies performed (p>0.05). UT had greater blood loss in L and M deformities, greater SICU admissions for L and S, longer hospital and greater revision surgery for implant failures for all deformities than TL (p<0.05). UT had fewer PJF for L deformities (p<0.05). Deformity correction and PROM improvement was similar UT vs TL for all cohorts at last follow up (p>0.05).
Conclusion(s): The theoretical benefits of UT fusion were not demonstrated for matched L, S and M patients receiving long fusion to the pelvis. UT had greater blood loss, hospital stay and revision surgery for implant failures than TL. For select deformities surgeons should consider TL UIV rather than UT; however, more research is needed to determine best outcomes for fusion levels for ASD. FDA DEVICE/DRUG STATUS: This abstract does not discuss or include any applicable devices or drugs.
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OBJECTIVE:To prioritize the cervical parameter targets for alignment. METHODS:Included: cervical deformity (CD) patients (C2-7 Cobb angle > 10°, cervical lordosis > 10°, cervical sagittal vertical axis [cSVA] > 4 cm, or chin-brow vertical angle > 25°) with full baseline (BL) and 1-year (1Y) radiographic parameters and Neck Disability Index (NDI) scores; patients with cervical [C] or cervicothoracic [CT] Primary Driver Ames type. Patients with BL Ames classified as low CD for both parameters of cSVA ( < 4 cm) and T1 slope minus cervical lordosis (TS-CL) ( < 15°) were excluded. Patients assessed: meeting minimum clinically important differences (MCID) for NDI ( < -15 ΔNDI). Ratios of correction were found for regional parameters categorized by primary Ames driver (C or CT). Decision tree analysis assessed cutoffs for differences associated with meeting NDI MCID at 1Y. RESULTS:Seventy-seven CD patients (mean age, 62.1 years; 64% female; body mass index, 28.8 kg/m2). Forty-one point six percent of patients met MCID for NDI. A backwards linear regression model including radiographic differences as predictors from BL to 1Y for meeting MCID for NDI demonstrated an R2 of 0.820 (p = 0.032) included TS-CL, cSVA, McGregor's slope (MGS), C2 sacral slope, C2-T3 angle, C2-T3 SVA, cervical lordosis. By primary Ames driver, 67.5% of patients were C, and 32.5% CT. Ratios of change in predictors for MCID NDI patients for C and CT were not significant between the 2 groups (p > 0.050). Decision tree analysis determined cutoffs for radiographic change, prioritizing in the following order: ≥ 42.5° C2-T3 angle, > 35.4° cervical lordosis, < -31.76° C2 slope, < -11.57-mm cSVA, < -2.16° MGS, > -30.8-mm C2-T3 SVA, and ≤ -33.6° TS-CL. CONCLUSION/CONCLUSIONS:Certain ratios of correction of cervical parameters contribute to improving neck disability. Prioritizing these radiographic alignment parameters may help optimize patient-reported outcomes for patients undergoing CD surgery.

BACKGROUND CONTEXT: Robot-guided lumbar instrumented fusion (RGLF) has the potential to improve safety and accuracy of pedicle screw placement. However, there are pitfalls in adopting this new technology and, as in adopting any new OR technology, there may be early complications. Optimizing workflow by avoiding interbody placement prior to pedicle screws placement (interbody-first workflow, IFW) and using caution in patients with poor bone quality (L1 Hounsfield units [HU] under 148) may improve outcomes. PURPOSE: To determine risk factors for robot-related complications and suggest optimal OR workflow. STUDY DESIGN/SETTING: Single-center retrospective study. PATIENT SAMPLE: A total of 344 RGLF cases from 2018 to 2021. OUTCOME MEASURES: L1 and UIV HU, levels fused, L5-S1 inclusion, interbody placed first workflow (IFW), hyperlordotic interbody, robot registration method, robot registration failure, intraoperative robot mechanical failures and pedicle screw malpositioning.
METHOD(S): Retrospective analysis of RGLFs at a single institution. Univariate analysis with t-tests, Mann-Whitney U tests, or chi-squared analysis assessed demographics, L1 and UIV HU, levels fused, L5-S1 inclusion, IFW, hyperlordotic cage, and robot registration method as risk factors for robot registration failure, intraoperative robot mechanical failures, and pedicle screw malpositioning. Multivariate logistic regression of risk factors approaching or achieving significance was conducted. A receiver operating characteristic (ROC) curve was created to determine a threshold for independent risk factors.
RESULT(S): A total of 344 RGLFs were included. In registered vs registration failure cases, smoking (12.73% vs 28.57%; p=0.041), L1HU (139.81+/-46.86 vs 177.16+/-55.74; p=0.009), L5-S1 inclusion (50.00% vs 80.95%; p=0.006), and IFW (58.07% vs 85.71%; p=0.014) were significant risk factors on univariate analysis. On multivariate analysis, smoking (p=0.003), L1HU (p=0.006), and L5-S1 inclusion (p=0.022) were independent risk factors and IFW approached significance (p=0.099) for risk of registration failure. In successful vs all robot failures cases, age (55.72+/-13.38 vs 59.92+/-11.38 years; p=0.046), female gender (48.70% vs 69.44%; p=0.018), levels fused (1.37+/-0.63 vs 1.67+/-0.76; p=0.010), L5-S1 inclusion (50.00% vs 69.44%; p=0.027), and IFW (57.47% vs 77.78%; p=0.012) were significant risk factors on univariate analysis. On multivariate analysis, female gender (p=0.047) and L5-S1 inclusion (p=0.049) were independent risk factors and IFW approached significance (p=0.055) for risk of mechanical failure. In successful vs pedicle screw malpositioned cases, IFW was a significant independent risk factor for pedicle screw malpositioning on multivariate analysis (p=0.038). On subanalysis of 124 robot-guided anterior-posterior lumbar fusion (RG APLF), L1 HU was an independent risk factors for registration failure (p=0.007) and approached significance for mechanical failures (p=0.051). ROC analysis revealed a cutoff of L1 HU of 148.55 for mechanical failures (area under the curve = 0.778). Levels fused (1.41+/-0.69 vs 2.00+/-0.54; p=0.018) was a significant risk factor for pedicle screw malpositioning on univariate analysis.
CONCLUSION(S): In all RGLFs, IFW was a risk factor for robot-related complications. In RG APLF, low L1 HU was a risk factor. Robot-related complications may be avoided by placing pedicle screws prior to interbody and by using caution in patients with poor bone quality. FDA DEVICE/DRUG STATUS: This abstract does not discuss or include any applicable devices or drugs.
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BACKGROUND CONTEXT: Preoperative opioid consumption, poor mental health, and lower socioeconomic status are each associated with worse surgical outcomes for adult spinal deformity (ASD). Little data exits evaluating preoperative morphine milligram equivalent (MME) consumption and preoperative mental health, social function, and socioeconomic status in ASD. PURPOSE: Evaluate the correlations between preoperative daily MME consumption and preoperative depression, anxiety, mental health scores, and socioeconomic status for ASD patients prior to receiving reconstructive ASD surgery. We hypothesized that preoperative MME consumption correlates with preoperative depression, anxiety, poor mental health, poor social function, and poor socioeconomic status in ASD. STUDY DESIGN/SETTING: Preoperative analysis of ASD patients prospectively enrolled into a multicenter study. PATIENT SAMPLE: ASD patients prospectively enrolled into multicenter study. OUTCOME MEASURES: Numeric rating scale (NRS) back and leg pain, Scoliosis Research Society-22r questionnaire (SRS-22r), Edmonton Frailty Index (EFI score), grip strength, Veterans Rand Health Questionnaire (VR-12), Oswestry Disability Index (ODI), daily morphine milligram equivalent consumption (MME), PROMIS-Pain Interference (PROMIS-PI), PROMIS-Physical Function (PROMIS-PF), PROMIS-Depression (DEP), PROMIS-Anxiety (ANX), PROMIS-Satisfaction with Social Roles (SR) and PROMIS-Satisfaction with Discretionary Social Activities (SDA) computer adaptive tests (CATs), Area Deprivation Index (ADI) scores.
METHOD(S): From 2018-2020, ASD patients were prospectively enrolled into a multicenter study. Preoperative MME was calculated. Preoperative PROMIS-DEP, PROMIS-ANX, PROMIS=SR, PROMIS-SDA, PROMIS-PI and PF, SRS-22r total and domain scores, and VR-12 mental component summary (MCS) were calculated. ADI scores were collected to assess socioeconomic status, as previously described. MME data were log transformed and two-tailed Pearson correlation coefficients calculated. Correlation strengths were interpreted according to Cohen. Confidence intervals were created with 1,000 sample bootstrapping.
RESULT(S): A total of 207/207 patients enrolled were evaluated; mean age 61 years (18-81). Preoperative opioid consumption was reported in 38% patients (n=78; mean preoperative MME 22.5 mg, range 1-420 mg). Preoperative MME did not correlate with PROMIS-ANX (p=0.07) and did not correlate with socioeconomic status (ADI; p=0.37). Preoperative MME showed small correlations with PROMIS-DEP (r=0.2, p=0.01), VR-12 MCS (r=-.2, p=0.002), and SRS-Mental Health (r=-0.2, p=0.005). Preoperative MME showed moderate correlations with PROMIS-PI (r=0.4, p<0.0001), PROMIS-PF (r=-0.4, p<0.0001), SRS-Pain (r=-0.5, p<0.0001), SRS-Function (r=-0.4, p<0.0001), PROMIS-SR (r=-0.3, p<0.0001) and PROMIS-SSA (r=-0.4, p<0.0001).
CONCLUSION(S): Prospective evaluation of 207 ASD patients demonstrated minimal to no correlations between preoperative MME consumption and preoperative anxiety, depression or low socioeconomic status. Preoperative MME consumption demonstrated moderate correlations with preoperative pain, physical function, and social function scores. The negative impacts of opioid consumption on physical measures are likely independent of psychosocial variables in ASD. FDA DEVICE/DRUG STATUS: This abstract does not discuss or include any applicable devices or drugs.
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BACKGROUND CONTEXT: Surgeons may preferentially limit fusion levels for younger vs older ASD patients to maintain motion segments and optimize postoperative function. Few data exist comparing the functional impact of upper thoracic (UT) vs thoracolumbar (TL) upper instrumented vertebra (UIV) in younger vs older ASD patients undergoing long fusion to the pelvis. PURPOSE: Evaluate patient reported functional impact of UT vs TL UIV in younger vs older ASD patients undergoing long fusion to the pelvis. STUDY DESIGN/SETTING: Propensity score matched (PSM) analysis of ASD patients prospectively enrolled into a multicenter study. PATIENT SAMPLE: Surgically treated ASD patients prospectively enrolled into multicenter study. OUTCOME MEASURES: Numeric rating scale (NRS) back and leg pain, Scoliosis Research Society-22r questionnaire (SRS-22r), Short Form-36v2 questionnaire (SF-36), Oswestry Disability Index (ODI), estimated blood loss, duration of hospital stay, postoperative complications, revision spine surgery.
METHOD(S): Surgically treated ASD patients prospectively enrolled into a multicenter ASD study were divided into 2 age groups (younger= <65 years, older= > 65 years) and separated according to UIV (TL= L2-T7; UT= T6-T1). Study inclusion criteria; 1) surgery for Lumbar (L), Sagittal (S), or Mixed (M) deformities (as per SRS-Schwab ASD classification), 2) fusion to the pelvis, 3) minimum 5 levels fused, and 4) minimum 2 year postop follow up. Surgery for double major or thoracic scoliosis were excluded. PSM was used to match preop patient demographics, scoliosis, and sagittal spinopelvic parameters including PI-LL, TK, SVS, and TPA. Surgical data evaluated and impact of UIV upon patient reported functional outcomes compared for UT vs TL for younger vs older.
RESULT(S): From 2008-2018, 435 of 717 eligible surgically treated patients were evaluated; younger (n=193; mean age 57.6 years) and older (n=242; mean age 72.3 years), mean levels fused UT=17.4, TL=10.7 (p<0.05). Preop spine deformity, demographics, and performance of osteotomies were similar for matched UT vs TL in younger and older (p>0.05). Surgical blood loss, duration of SICU and hospital stay was greater for UT vs TL in younger and older (p<0.05). UT had more revision surgery than TL due to implant failures in younger (20% vs 3%) and older (16% vs 1%), respectively (p<0.05). Older UT had more major complications than older TL (65% vs 30%). At minimum 2 year postoperative follow up spine deformity correction and all PROMs (including improvements and final values) including SRS-22r activity, SF-36 physical function, SF-36 role physical, SF-36 social function and SF-36 vitality were similar UT vs TL in younger and older (p>0.05).
CONCLUSION(S): Younger ASD patients fused to the pelvis do not report more physical restrictions for UT vs TL UIV compared to older ASD patients, however blood loss, SICU and hospital stay and complications were greater for UT vs TL in younger and older cohorts. When deciding upon UIV for ASD patients, the minimal impact of UT vs TL UIV upon patient reported outcomes must be offset by cognizance of a longer hospital stay and potential for greater postoperative complications for UT fusions especially in older patients. FDA DEVICE/DRUG STATUS: This abstract does not discuss or include any applicable devices or drugs.
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BACKGROUND CONTEXT: Cervical deformity (CD) surgery can markedly improve patient quality of life. The longevity of CD correction and the mechanism of alignment deterioration are not well understood. PURPOSE: To investigate preoperative risk factors and failure mechanisms that erode CD corrections and the impact on functional outcomes. STUDY DESIGN/SETTING: Retrospective review of a prospective CD database. PATIENT SAMPLE: This study included 155 operative CD patients with baseline (BL) and 1-year follow-up. OUTCOME MEASURES: Alignment at baseline, 3 months, 6 months and 1 year: cervical sagittal vertical axis (cSVA), C2 Slope (C2S), T1 slope (T1S), C2-C7 lordosis (CL), T1S-CL mismatch (TS-CL), Neck Disability Index (NDI), Modified Japanese Orthopaedic Association score (mJOA).
Method(s): A retrospective review of a prospective database of operative CD patients was analyzed. Patients with baseline, 3-month, 6-month and 1-year cervical radiographs were included. Cervical sagittal vertical axis (cSVA) <4cm was used to categorize patients as well-aligned vs malaligned. Additionally, three subsets were defined as follows: (1) patients who were malaligned preoperatively (cSVA>=4) and remained well aligned at 1 year postoperatively; (2) patients who were well-aligned but experienced alignment deterioration (cSVA>=4cm) up to 1 year postop, and; (3) patients who never attained cSVA <4cm. These groups were compared in terms of demographic factors, surgical factors, baseline radiographic parameters and radiographic and surgical outcomes at baseline and 1 year, using t-tests and X2 tests for continuous and categorical variables, respectively.
Result(s): A total of 155 patients were included (mean age 61.41, 60.9% F). The entire cohort was analyzed at all time points for alignment using cSVA. Among 89 patients with X-rays at every time point, 30 patients (34%) maintained their good alignment correction at 1-year postop. Seventeen patients (19%) experienced alignment deterioration and 42 patients (46%) never reached cSVA <4cm at any time point. Four patients lost their correction at 3 months, 6 patients at 6 months and 8 patients were malaligned by 1 year. The never-aligned cohort was significantly older when compared to those who maintained alignment or those who deteriorated (65.9 vs 61.8 vs 58.8, p=0.038). Patients who never achieved good alignment and those who suffered deterioration had a significantly higher rate of DJK (42.9% vs 47.1% vs 3.3%, p=0.001). Other failure mechanisms in the deterioration group included loss of subjacent spinopelvic compensation and PJK. At baseline, patients with alignment deterioration had a smaller cSVA compared to those who maintained or never reached good alignment (40.5 vs 52.0 and 60.1mm, p=0.001), and less TK (-43.4 vs -55.9 vs -61.4, p=0.049). At 1-year postop, patients with deterioration had worsening of their mJOA score at 6 months compared to those who maintained or never reached proper alignment (2.50 vs 0.04 vs 1.20, p=0.032). There were no significant differences in smokers, BMI, frailty, osteoporosis, levels fused, UIV, LIV, EBL, operative time, rod diameter, rod material, utilization 3-column osteotomy, mean osteotomy grade, in construct (fused) loss of alignment or revision rate between the groups (all p>.05)
Conclusion(s): Cervical deformity correction surgery failed to achieve acceptable sagittal alignment in 46% of patients. In those with successful correction, 36% suffered alignment deterioration within 1 year. Distal junctional kyphosis was the most common failure mechanism leading to loss of correction. FDA DEVICE/DRUG STATUS: This abstract does not discuss or include any applicable devices or drugs.
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BACKGROUND CONTEXT: Both frailty and surgical invasiveness are correlated with increased risk of complications following ASD surgery, yet there is no accepted risk-stratification system combining these factors. PURPOSE: The aim of this study is to ascertain data-driven categories defining the risk for 90-day complications following ASD surgery based on frailty and surgical invasiveness. STUDY DESIGN/SETTING: Retrospective review of a multicenter database. PATIENT SAMPLE: A total of 1,272 surgical ASD patients undergoing spinal fusions >=5 levels OUTCOME MEASURES: Ninety-day complication risk, 90-day complication rate, invasiveness thresholds for increased complications.
METHOD(S): Using a prospective, multicenter database, we identified 1,272 surgical ASD patients undergoing posterior spinal fusion of at least five levels. Patients were separated into three frailty groups based on the ASD-FI frailty index. Within each frailty group, stratum-specific likelihood ratio (SSLR) analyses were performed to define frailty-based surgical invasiveness cutoffs associated with increased risk for 90-day complications. Cutoffs generated through SSLR were confirmed with multivariable logistic regression analysis controlling for age, alignment, and ODI.
RESULT(S): Mean age was 60 +/- 14 years, 74% females. Of 1,272 surgical ASD patients, 319 (35%) were nonfrail (NF), 667 (52%) frail (F), and 286 (23%) severely frail (SF). Mean SI was 93 +/- 35. The mean complication rate was 35.4% for NF, 37% for F and 43.6% for SF. SSLR analysis of NF patients produced 2 complication categories: 33% complication rate for SI < 153 and 73% for SI >= 153. NF patients with SI >= 153 had 4.14x higher odds of complications than NF patients with SI <153 (p=0.04). SSLR analysis of F patients produced 3 complication categories: 26% complication rate for SI < 60, 42% for SI of 60 to 179, and 64% for SI >= 180. Relative to F patients with SI < 60, F patients with SI 60 to 179, and SI >= 180 had 2.4x and 6.7x higher odds of complications, respectively (p<0.01 for both). SSLR analysis of SF patients produced 2 complication categories: 35% complication rate for SI < 82 and 49% complication rate for SI >= 82. SF patients with SI >= 82 had 1.77x higher odds of complications than SF patients with SI < 82 (p=0.04).
CONCLUSION(S): Frailer groups were found to have lower SI cutoffs, indicating the less invasiveness surgeries can be performed on frail patients to minimize complication risk. This risk-stratification system is useful for counselling patients regarding their risk of complication. FDA DEVICE/DRUG STATUS: This abstract does not discuss or include any applicable devices or drugs.
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BACKGROUND CONTEXT: Cervical alignment and cervical deformity surgery are complex topics. Recently, a score inspired by work on thoracolumbar alignment was developed for cervical alignment (cervical deformity score, CDS). While this score was designed to predict early mechanical failures, its association with patient reported outcomes (PROM) remains unclear. PURPOSE: Investigate the association between PROM, complications, and a newly described cervical deformity score. STUDY DESIGN/SETTING: Retrospective review of prospective multicenter database. PATIENT SAMPLE: A total of 102 adult cervical deformity (CD) patients with at least 1 year follow-up. OUTCOME MEASURES: NDI, neck pain, EQ5D, complication rates.
Method(s): CD patients with baseline and 1-year follow-up were included. Postoperative CDS was constructed using offset from age-adjusted values: SVA [(age -55)*2+25], T1 Slope [(age -55)/4 + 28.7], and TS minus CL [cst: between 26.5 and 14.5degree]. Points were assigned based on the offset from alignment targets and the CDS was the sum of the three individual scores. Association with patient-reported outcomes was investigated using Pearson's correlations. Comparison of CDS between patients with and without complication within 1-year was conducted. Logistical regression controlling for demographic and comorbidities was conducted to identify if CDS was an independent predictor of complications.
Result(s): A total of 102 patients met inclusion criteria (61.7yo+/-10, 66.7% F); 37.6% of them had a history of previous cervical surgery (16.7% previous ACDF, 11.7% previous posterior fusion). Preoperatively, they had elevated disability (NDI: 47.1+/-18.1), pain (NSR Neck: 6.6+/-2.5), myelopathy (mJOA: 13.6+/-2.7) and lower general health (EQ5D: 0.74+/-0.07). They also presented with an overall cervical kyphotic alignment (C2-C7: -6.3degree+/-20.9), a moderate cervical anterior alignment (cSVA: 39mm+/-20; TS-CL: 37.9degree+/-19.4) and a posterior global thoracolumbar alignment (SVA: -3mm+/-68). The median of number of levels fused was 7 [4-9], with 49% treated with a posterior approach and 30.4% with a combined approach; 83.2% received an osteotomy, 44.6% some posterior osteotomy, 16.8% grade 6 or 7. The mean operative time was 368min+/-208, median EBL was 525cc [200 1025], and LOS was 5 days [4 8]. At 1 year, patients improved significantly in terms of disability (NDI: 36.2+/-20.7, 60.8% reached MCID), pain (NSR: 4.1+/-2.9) and general health (EQ5D: 0.79+/-0.08) (all p<0.001). The cervical alignment significantly changed (C2-C7: 7.8+/-14.5m; cSVA: 34mm+/-15; TS-CL: 28.9degree+/-12.6 all p <0.002), with a 1-year CDS of 1.68+/-2.46 (prctl [0 3.25]). There was a significant association between increased CDS and increased disability (r=0.273), pain (r=0.336) and lower general health (r=-0.283). Patient with a lower disability level (NDI<20) had a significantly lower CDS (0.71+/-2.3 vs 2.16+/-2.4 p<0.004). Patients without any complications before 1 year had a lower CDS (0.78+/-2.33 vs 2.18+/-2.40 p=0.005), as did patients without major complications (1.36+/-2.27 vs 2.50+/-.78 p=0.037). Deeper analysis revealed significant differences in terms of CDS for patients experiencing cardiopulmonary, instrumentation and radiographic complications (p<0.05). Multivariate analysis, controlling for age and comorbidities, show 1-year CDS to be a significant predictor of complication (p=0.002, OR=1.409).
Conclusion(s): With better outcomes and lower complication rate, maintaining a proportionate alignment postoperatively can result in superior outcomes following CD surgery. FDA DEVICE/DRUG STATUS: This abstract does not discuss or include any applicable devices or drugs.
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BACKGROUND CONTEXT: A previous study utilized normative alignment to determine overcorrections and predict mechanical complications in adult spinal deformity (ASD) surgery. Other studies have recommended alignment targets that optimize age-appropriate physical function. The difference in functional outcomes and mechanical complications between these prescribed alignment targets has not been explored. This study utilizes a component angle of the T1 pelvic angle (TPA) within the fusion to compare normative and age-pelvic incidence (PI) optimal alignment in terms of proximal junctional kyphosis (PJK), proximal junctional failure (PJF) and health related quality of life measures (HRQL). Using the component of TPA within the fusion, the T4-pelvic angle (T4PA), allows for the measurement spinopelvic alignment separate from that of the unfused thoracic spine and any PJK that may occur postoperatively. PURPOSE: To compare ASD patients corrected to normative alignment vs age-PI optimal alignment in terms of PJK/PJF and outcomes. STUDY DESIGN/SETTING: Retrospective analysis of a prospective multicenter ASD database and a database of asymptomatic subjects. PATIENT SAMPLE: This study included 1,916 ASD patients and 118 asymptomatic subjects for formula development; 288 ASD patients with 2-year X-ray and HRQL follow-up. OUTCOME MEASURES: SF36-PCS, ODI, SRS-22, NRS back/leg, PJK (change in UIV to UIV+2 >10degree), PJF (defined as severe PJK with change >21.6degree, or UIV olisthesis, or proximal junctional fracture).
METHOD(S): Baseline relationships between age, PI and T4PA, were analyzed in the ASD patients and compared to the asymptomatic subjects. Linear regression modeling was used to determine alignment based on PI and age in asymptomatic subjects (normative alignment), and in ASD patients, alignment corresponding to age-appropriate functional status (optimal alignment). ASD patients with UIV above T4 were grouped based on their corrections: normative vs optimal. Extreme over or under corrected patients were excluded (greater than or less than 2SD from mean postop T4PA). For each group, the rate of PJK and PJF were determined.
RESULT(S): In the multilinear regression analysis of the 119 asymptomatic subjects, T4PA correlated with age and PI, r=.713, p<.0001. 1916 ASD patients were included in the optimal formula development. In the 288 ASD patients included in the pre- to postop analysis (137 normative, 151 optimal), there was no difference in baseline alignment or HRQL between the groups. At 6 weeks, the normative aligned group had smaller T4PA (4.45 vs 14.1) and PI-LL (-7.24 vs 7.4), all p<.0001. Normative aligned patients had the higher PJK rate (40% vs 27.2%, p=.03) compared with optimal; and a higher PJF rate (17% vs 6.8%, p=.008). PJF patients had -1.2degreeof T4PA offset from normative alignment and -5.2degreeof offset from optimal alignment. By contrast, no PJF patients had 3.8degree of T4PA offset from normative alignment and -0.42degree of offset from optimal alignment. There was a trend toward worse 2-year SF36-PCS in patients who suffered PJF (37.7 vs 41.6, p=.09). Both the Normative and Optimal groups improved in outcomes from baseline to 2-year (p<.001) with no difference in 2-year HRQL.
CONCLUSION(S): Correcting ASD patients to normative alignment resulted in higher rates of PJK and PJF without improvements in HRQL. ASD patients should not be corrected to match the alignment of their asymptomatic unfused peers, rather they should be realigned optimally to match age-appropriate physical function. 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 costly and carries a high complication rate. It is therefore very important to optimize value (cost-per-QALY) or cost-utility in ASD surgery. To identify targets for improvement, we compared the influence of patient factors, measured by frailty, vs surgical factors, measured by surgical invasiveness (SI), on 2-year cost-utility. Patient frailty is an approximation of baseline patient health status, whereas SI represents extensiveness of the surgical intervention. Data comparing the relative importance of these aggregate measures on cost-utility are limited. Additionally, this analysis can serve to help identify the most impactful modifiable factors in the value equation. PURPOSE: The aim of this study was to assess whether frailty or SI is a more important determinant of 2-year cost-utility in ASD surgery. STUDY DESIGN/SETTING: Prospective, multicenter study. PATIENT SAMPLE: ASD patients with >4-level fusion and eligible for minimum 2-year follow-up were included. OUTCOME MEASURES: Two-year cost-per-QALY.
METHOD(S): Index and total episode of care (EOC; iEOC; tEOC) cost was calculated using Medicare's inpatient prospective payment system (IPPS) for MS-DRGs 453-460. All costs were adjusted for inflation to 2020 US dollar values. QALYs gained were calculated using baseline, 1-year, and 2-year SF-6D scores. A discount rate of 3% was assumed. Cost-per-QALY was determined by calculating total EOC per cumulative QALY at two years. Patients were categorized as not-frail (NF, <0.3), frail (F, 0.3<= to <0.5), and severely frail (SF, >0.5). SI was categorized as low-SI (SI<90) and high-SI (SI>90). A generalized linear model with gamma error distribution and log link was used to estimate the association between frailty and SI on cost-per-QALY. All analyses were controlled for gender and blood loss. Other variables commonly adjusted for (ie, age, levels fused) were intentionally not controlled for in this analysis to avoid collinearity with either frailty or SI.
RESULT(S): DRG data for index and revision surgery was available for 505/889 patients. Mean age was 62.5+12.4years, 76% were women, and 91% were Caucasian. Of the total patients,72% demonstrated positive gain in QALY at 2 years (0.12+0.09, p<0.001) compared to baseline. The mean iEOC was $72,717, tEOC was $86,066, and cost-per-QALY was $52,357. Eighty-nine patients had 114 (range 1-5) revisions (17.6%) compared to 416 without. The tEOC in revision group was $151,913 compared to $71,978 in the non-revision group with 2-year cost-per-QALY 98,262 compared to 42,537, respectively. On adjusted analysis, F and SF patients compared to NF patients had significantly higher cost-per-QALY (p<0.0001 for all comparisons) regardless of the surgical invasiveness. However, SI was not significantly associated with cost-per-QALY regardless of patient's frailty.
CONCLUSION(S): Increasing levels of frailty were associated with significantly and incrementally higher values of 2-year cost-per-QALY in both low and high SI groups. However, within each frailty group, the high and low SI groups had equivalent cost-per-QALY. Frailty appears to be a better determinant of 2-year cost-per-QALY compared to surgical invasiveness. Surgeons should place more importance on modifiable patient factors compared to surgical factors to improve or optimize 2-year cost-utility in ASD surgery. FDA DEVICE/DRUG STATUS: This abstract does not discuss or include any applicable devices or drugs.
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