Factors Associated with the Maintenance of Cost-Effectiveness at 5 Years in Adult Spinal Deformity Corrective Surgery.

STUDY DESIGN: Retrospective cohort. OBJECTIVE: To evaluate factors associated with the long-term durability of cost-effectiveness (CE) in ASD patients. BACKGROUND: A substantial increase in costs associated with the surgical treatment for adult spinal deformity (ASD) has given precedence to scrutinize the value and utility it provides. METHODS: We included 327 operative ASD patients with 5-year (5 Y) follow-up. Published methods were used to determine costs based on CMS.gov definitions and were based on the average DRG reimbursement rates. Utility was calculated using quality-adjusted life-years (QALY) utilizing the Oswestry Disability Index (ODI) converted to Short-Form Six-Dimension (SF-6D), with a 3% discount applied for its decline with life expectancy. The CE threshold of $150,000 was used for primary analysis. RESULTS: Major and minor complication rates were 11% and 47% respectively, with 26% undergoing reoperation by 5 Y. The mean cost associated with surgery was $91,095±$47,003, with a utility gain of 0.091±0.086 at 1Y, QALY gained at 2 Y of 0.171±0.183, and at 5 Y of 0.42±0.43. The cost per QALY at 2 Y was $414,885, which decreased to $142,058 at 5 Y.With the threshold of $150,000 for CE, 19% met CE at 2 Y and 56% at 5 Y. In those in which revision was avoided, 87% met cumulative CE till life expectancy. Controlling analysis depicted higher baseline CCI and pelvic tilt (PT) to be the strongest predictors for not maintaining durable CE to 5 Y (CCI OR: 1.821 [1.159-2.862], P=0.009) (PT OR: 1.079 [1.007-1.155], P=0.030). CONCLUSIONS: Most patients achieved cost-effectiveness after four years postoperatively, with 56% meeting at five years postoperatively. When revision was avoided, 87% of patients met cumulative cost-effectiveness till life expectancy. Mechanical complications were predictive of failure to achieve cost-effectiveness at 2 Y, while comorbidity burden and medical complications were at 5 Y.

AM-PAC Mobility Score <13 Predicts Development of Ileus Following Adult Spinal Deformity Surgery.

STUDY DESIGN: Retrospective review. OBJECTIVE: To determine whether the Activity Measure for Post-Acute Care (AM-PAC) "6-Clicks" score is associated with the development of postoperative ileus. SUMMARY OF BACKGROUND DATA: Adult spinal deformity (ASD) surgery has a high complication rate. One common complication is postoperative ileus, and poor postoperative mobility has been implicated as a modifiable risk factor for this condition. METHODS: Eighty-five ASD surgeries in which ≥5 levels were fused were identified in a single institution database. A physical therapist/physiatrist collected patients' daily postoperative AM-PAC scores, for which we assessed first, last, and daily changes. We used multivariable linear regression to determine the marginal effect of ileus on continuous AM-PAC scores; threshold linear regression with Bayesian information criterion to identify a threshold AM-PAC score associated with ileus; and multivariable logistic regression to determine the utility of the score thresholds when controlling for confounding variables. RESULTS: Ten of 85 patients (12%) developed ileus. The mean day of developing ileus was postoperative day 3.3±2.35. The mean first and last AM-PAC scores were 16 and 18, respectively. On bivariate analysis, the mean first AM-PAC score was lower in patients with ileus than in those without (13 vs. 16; P<0.01). Ileus was associated with a first AM-PAC score of 3 points lower (Coef. -2.96; P<0.01) than that of patients without ileus. Patients with an AM-PAC score<13 had 8 times greater odds of developing ileus (P=0.023). Neither the last AM-PAC score nor the daily change in AM-PAC score was associated with ileus. CONCLUSIONS: In our institutional cohort, a first AM-PAC score of <13, corresponding to an inability to walk or stand for more than 1 minute, was associated with the development of ileus. Early identification of patients who cannot walk or stand after surgery can help determine which patients would benefit from prophylactic management. LEVEL OF EVIDENCE: Level-III.

Stronger association of objective physical metrics with baseline patient-reported outcome measures than preoperative standing sagittal parameters for adult spinal deformity patients.

OBJECTIVE: Sagittal alignment measured on standing radiography remains a fundamental component of surgical planning for adult spinal deformity (ASD). However, the relationship between classic sagittal alignment parameters and objective metrics, such as walking time (WT) and grip strength (GS), remains unknown. The objective of this work was to determine if ASD patients with worse baseline sagittal malalignment have worse objective physical metrics and if those metrics have a stronger relationship to patient-reported outcome metrics (PROMs) than standing alignment. METHODS: The authors conducted a retrospective review of a multicenter ASD cohort. ASD patients underwent baseline testing with the timed up-and-go 6-m walk test (seconds) and for GS (pounds). Baseline PROMs were surveyed, including Oswestry Disability Index (ODI), Patient-Reported Outcomes Measurement Information System (PROMIS), Scoliosis Research Society (SRS)-22r, and Veterans RAND 12 (VR-12) scores. Standard spinopelvic measurements were obtained (sagittal vertical axis [SVA], pelvic tilt [PT], and mismatch between pelvic incidence and lumbar lordosis [PI-LL], and SRS-Schwab ASD classification). Univariate and multivariable linear regression modeling was performed to interrogate associations between objective physical metrics, sagittal parameters, and PROMs. RESULTS: In total, 494 patients were included, with mean ± SD age 61 ± 14 years, and 68% were female. Average WT was 11.2 ± 6.1 seconds and average GS was 56.6 ± 24.9 lbs. With increasing PT, PI-LL, and SVA quartiles, WT significantly increased (p < 0.05). SRS-Schwab type N patients demonstrated a significantly longer average WT (12.5 ± 6.2 seconds), and type T patients had a significantly shorter WT time (7.9 ± 2.7 seconds, p = 0.03). With increasing PT quartiles, GS significantly decreased (p < 0.05). SRS-Schwab type T patients had a significantly higher average GS (68.8 ± 27.8 lbs), and type L patients had a significantly lower average GS (51.6 ± 20.4 lbs, p = 0.03). In the frailty-adjusted multivariable linear regression analyses, WT was more strongly associated with PROMs than sagittal parameters. GS was more strongly associated with ODI and PROMIS Physical Function scores. CONCLUSIONS: The authors observed that increasing baseline sagittal malalignment is associated with slower WT, and possibly weaker GS, in ASD patients. WT has a stronger relationship to PROMs than standing alignment parameters. Objective physical metrics likely offer added value to standard spinopelvic measurements in ASD evaluation and surgical planning.

Impact of Controlled Versus Uncontrolled mFI-5 Frailty on Perioperative Complications After Adult Spinal Deformity Surgery.

STUDY DESIGN: Retrospective review. OBJECTIVES: We substratified the mFI-5 frailty index to reflect controlled and uncontrolled conditions and assess their relationship to perioperative complications. SUMMARY OF BACKGROUND DATA: Risk assessment before adult spinal deformity (ASD) surgery is critical because the surgery is highly invasive with a high complication rate. Although frailty is associated with risk of surgical complications, current frailty measures do not differentiate between controlled and uncontrolled conditions. METHODS: Frailty was calculated using the mFI-5 index for 170 ASD patients with fusion of ≥5 levels. Uncontrolled frailty was defined as blood pressure >140/90 mm Hg, HbA1C >7% or postprandial glucose >180 mg/dL, or recent chronic obstructive pulmonary disease (COPD) exacerbation, while on medication. Patients were divided into nonfrailty, controlled frailty, and uncontrolled frailty cohorts. The primary outcome measure was perioperative major and wound complications. Bivariate analysis was performed. Multivariable analysis assessed the relationship between frailty and perioperative complications. RESULTS: The cohorts included 97 nonfrail, 54 controlled frail, and 19 uncontrolled frail patients. Compared with nonfrail patients, patients with uncontrolled frailty were more likely to have age older than 60 years (84% vs. 24%), hyperlipidemia (42% vs. 20%), and Oswestry Disability Index (ODI) score >42 (84% vs. 52%) (P<0.05 for all). Controlled frailty was associated with those older than 60 years (41% vs. 24%) and hyperlipidemia (52% vs. 20%) (P<0.05 for all). On multivariable regression analysis controlling for hyperlipidemia, functional independence, motor weakness, ODI>42, and age older than 60 years, patients with uncontrolled frailty had greater odds of major complications (OR 4.24, P=0.03) and wound complications (OR 9.47, P=0.046) compared with nonfrail patients. Controlled frailty was not associated with increased risk of perioperative complications (P>0.05 for all). CONCLUSIONS: Although patients with uncontrolled frailty had higher risk of perioperative complications compared with nonfrail patients, patients with controlled frailty did not, suggesting the importance of controlling modifiable risk factors before surgery. LEVEL OF EVIDENCE: 3.

Are insufficient corrections a major factor in distal junctional kyphosis? A simulated analysis of cervical deformity correction using in-construct measurements.

OBJECTIVE: The present study utilized recently developed in-construct measurements in simulations of cervical deformity surgery in order to assess undercorrection and predict distal junctional kyphosis (DJK). METHODS: A retrospective review of a database of operative cervical deformity patients was analyzed for severe DJK and mild DJK. C2-lower instrumented vertebra (LIV) sagittal angle (SA) was measured postoperatively, and the correction was simulated in the preoperative radiograph in order to match the C2-LIV by using the planning software. Linear regression analysis that used C2 pelvic angle (CPA) and pelvic tilt (PT) determined the simulated PT that matched the virtual CPA. Linear regression analysis was used to determine the C2-T1 SA, C2-T4 SA, and C2-T10 SA that corresponded to DJK of 20° and cervical sagittal vertical axis (cSVA) of 40 mm. RESULTS: Sixty-nine cervical deformity patients were included. Severe and mild DJK occurred in 11 (16%) and 22 (32%) patients, respectively; 3 (4%) required DJK revision. Simulated corrections demonstrated that severe and mild DJK patients had worse alignment compared to non-DJK patients in terms of cSVA (42.5 mm vs 33.0 mm vs 23.4 mm, p < 0.001) and C2-LIV SVA (68.9 mm vs 57.3 mm vs 36.8 mm, p < 0.001). Linear regression revealed the relationships between in-construct measures (C2-T1 SA, C2-T4 SA, and C2-T10 SA), cSVA, and change in DJK (all R > 0.57, p < 0.001). A cSVA of 40 mm corresponded to C2-T4 SA of 10.4° and C2-T10 SA of 28.0°. A DJK angle change of 10° corresponded to C2-T4 SA of 5.8° and C2-T10 SA of 20.1°. CONCLUSIONS: Simulated cervical deformity corrections demonstrated that severe DJK patients have insufficient corrections compared to patients without DJK. In-construct measures assess sagittal alignment within the fusion separate from DJK and subjacent compensation. They can be useful as intraoperative tools to gauge the adequacy of cervical deformity correction.

Impact of Hip and Knee Osteoarthritis on Full Body Sagittal Alignment and Compensation for Sagittal Spinal Deformity.

STUDY DESIGN: Retrospective review of prospectively collected data. OBJECTIVE: To investigate the effect of lower extremity osteoarthritis on sagittal alignment and compensatory mechanisms in adult spinal deformity (ASD). BACKGROUND: Spine, hip, and knee pathologies often overlap in ASD patients. Limited data exists on how lower extremity osteoarthritis impacts sagittal alignment and compensatory mechanisms in ASD. METHODS: 527 pre-operative ASD patients with full body radiographs were included. Patients were grouped by Kellgren-Lawrence grade of bilateral hips and knees and stratified by quartile of T1-Pelvic Angle (T1PA) severity into low-, mid-, high-, and severe-T1PA. Full body alignment and compensation were compared across quartiles. Regression analysis examined the incremental impact of hip and knee osteoarthritis severity on compensation. RESULTS: The mean T1PA for low-, mid-, high-, and severe-T1PA groups was 7.3°, 19.5°, 27.8°, 41.6°, respectively. Mid-T1PA patients with severe hip osteoarthritis had an increased sagittal vertical axis and global sagittal alignment (P<0.001). Increasing hip osteoarthritis severity resulted in decreased pelvic tilt (P=0.001) and sacrofemoral angle (P<0.001), but increased knee flexion (P=0.012). Regression analysis revealed with increasing T1PA, pelvic tilt correlated inversely with hip osteoarthritis and positively with knee osteoarthritis (r2=0.812). Hip osteoarthritis decreased compensation via sacrofemoral angle (ß-coefficient=-0.206). Knee and hip osteoarthritis contributed to greater knee flexion (ß-coefficients=0.215, 0.101; respectively). For pelvic shift, only hip osteoarthritis significantly contributed to the model (ß-coefficient=0.100). CONCLUSIONS: For the same magnitude of spinal deformity, increased hip osteoarthritis severity was associated with worse truncal and full body alignment with posterior translation of the pelvis. Patients with severe hip and knee osteoarthritis exhibited decreased hip extension and pelvic tilt, but increased knee flexion. This examines sagittal alignment and compensation in ASD patients with hip and knee arthritis and may help delineate whether hip and knee flexion is due to spinal deformity compensation or lower extremity osteoarthritis.

Predictors of pelvic tilt normalization: a multicenter study on the impact of regional and lower-extremity compensation on pelvic alignment after complex adult spinal deformity surgery.

OBJECTIVE: The objective was to determine the degree of regional decompensation to pelvic tilt (PT) normalization after complex adult spinal deformity (ASD) surgery. METHODS: Operative ASD patients with 1 year of PT measurements were included. Patients with normalized PT at baseline were excluded. Predicted PT was compared to actual PT, tested for change from baseline, and then compared against age-adjusted, Scoliosis Research Society-Schwab, and global alignment and proportion (GAP) scores. Lower-extremity (LE) parameters included the cranial-hip-sacrum angle, cranial-knee-sacrum angle, and cranial-ankle-sacrum angle. LE compensation was set as the 1-year upper tertile compared with intraoperative baseline. Univariate analyses were used to compare normalized and nonnormalized data against alignment outcomes. Multivariable logistic regression analyses were used to develop a model consisting of significant predictors for normalization related to regional compensation. RESULTS: In total, 156 patients met the inclusion criteria (mean ± SD age 64.6 ± 9.1 years, BMI 27.9 ± 5.6 kg/m2, Charlson Comorbidity Index 1.9 ± 1.6). Patients with normalized PT were more likely to have overcorrected pelvic incidence minus lumbar lordosis and sagittal vertical axis at 6 weeks (p < 0.05). GAP score at 6 weeks was greater for patients with nonnormalized PT (0.6 vs 1.3, p = 0.08). At baseline, 58.5% of patients had compensation in the thoracic and cervical regions. Postoperatively, compensation was maintained by 42% with no change after matching in age-adjusted or GAP score. The patients with nonnormalized PT had increased rates of thoracic and cervical compensation (p < 0.05). Compensation in thoracic kyphosis differed between patients with normalized PT at 6 weeks and those with normalized PT at 1 year (69% vs 35%, p < 0.05). Those who compensated had increased rates of implant complications by 1 year (OR [95% CI] 2.08 [1.32-6.56], p < 0.05). Cervical compensation was maintained at 6 weeks and 1 year (56% vs 43%, p = 0.12), with no difference in implant complications (OR 1.31 [95% CI -2.34 to 1.03], p = 0.09). For the lower extremities at baseline, 61% were compensating. Matching age-adjusted alignment did not eliminate compensation at any joint (all p > 0.05). Patients with nonnormalized PT had higher rates of LE compensation across joints (all p < 0.01). Overall, patients with normalized PT at 1 year had the greatest odds of resolving LE compensation (OR 9.6, p < 0.001). Patients with normalized PT at 1 year had lower rates of implant failure (8.9% vs 19.5%, p < 0.05), rod breakage (1.3% vs 13.8%, p < 0.05), and pseudarthrosis (0% vs 4.6%, p < 0.05) compared with patients with nonnormalized PT. The complication rate was significantly lower for patients with normalized PT at 1 year (56.7% vs 66.1%, p = 0.02), despite comparable health-related quality of life scores. CONCLUSIONS: Patients with PT normalization had greater rates of resolution in thoracic and LE compensation, leading to lower rates of complications by 1 year. Thus, consideration of both the lower extremities and thoracic regions in surgical planning is vital to preventing adverse outcomes and maintaining pelvic alignment.

Lumbar Lordosis Redistribution and Segmental Correction in Adult Spinal Deformity (ASD): Does it Matter?

STUDY DESIGN: Retrospective analysis of prospectively collected data. OBJECTIVE: Evaluate the impact of correcting to normative segmental lordosis values on post-operative outcomes. BACKGROUND: Restoring lumbar lordosis magnitude is crucial in adult spinal deformity surgery, but the optimal location and segmental distribution remains unclear. METHODS: Patients were grouped based on offset to normative segmental lordosis values, extracted from recent publications. Matched patients were within 10% of the cohort's mean offset, less than or over 10% were under- and over-corrected. Surgical technique, PROMs, and surgical complications were compared across groups at baseline and 2-year. RESULTS: 510 patients with an average age of 64.6, mean CCI 2.08, and average follow-up of 25 months. L4-5 was least likely to be matched (19.1%), while L4-S1 was the most likely (24.3%). More patients were overcorrected at proximal levels (T10-L2; Undercorrected, U: 32.2% vs. Matched, M: 21.7% vs. Overcorrected, O: 46.1%) and undercorrected at distal levels (L4-S1: U: 39.0% vs. M: 24.3% vs. O: 36.8%). Postoperative ODI was comparable across correction groups at all spinal levels except at L4-S1 and T10-L2/L4-S1, where overcorrected patients and matched were better than undercorrected (U: 32.1 vs. M: 25.4 vs. O: 26.5, P=0.005; U: 36.2 vs. M: 24.2 vs. O: 26.8, P=0.001; respectively). Patients overcorrected at T10-L2 experienced higher rates of proximal junctional failure (PJF) (U: 16.0% vs. M: 15.6% vs. O: 32.8%, P<0.001) and had greater posterior inclination of the upper instrumented vertebra (UIV) (U: -9.2±9.4° vs. M: -9.6±9.1° vs. O: -12.2±10.0°, P<0.001), whereas undercorrection at these levels led to higher rates of revision for implant failure (U: 14.2% vs. M: 7.3% vs. O: 6.4%, P=0.025). CONCLUSIONS: Patients undergoing fusion for adult spinal deformity suffer higher rates of PJF with overcorrection and increased rates of implant failure with undercorrection based on normative segmental lordosis. LEVEL OF EVIDENCE: IV.

Persistent Lower Extremity Compensation for Sagittal Imbalance After Surgical Correction of Complex Adult Spinal Deformity: A Radiographic Analysis of Early Impact.

BACKGROUND AND OBJECTIVES: Achieving spinopelvic realignment during adult spinal deformity (ASD) surgery does not always produce ideal outcomes. Little is known whether compensation in lower extremities (LEs) plays a role in this disassociation. The objective is to analyze lower extremity compensation after complex ASD surgery, its effect on outcomes, and whether correction can alleviate these mechanisms. METHODS: We included patients with complex ASD with 6-week data. LE parameters were as follows: sacrofemoral angle, knee flexion angle, and ankle flexion angle. Each parameter was ranked, and upper tertile was deemed compensation. Patients compensating and not compensating postoperatively were propensity score matched for body mass index, frailty, and T1 pelvic angle. Linear regression assessed correlation between LE parameters and baseline deformity, demographics, and surgical details. Multivariate analysis controlling for baseline deformity and history of total knee/hip arthroplasty evaluated outcomes. RESULTS: Two hundred and ten patients (age: 61.3 ± 14.1 years, body mass index: 27.4 ± 5.8 kg/m2, Charlson Comorbidity Index: 1.1 ± 1.6, 72% female, 22% previous total joint arthroplasty, 24% osteoporosis, levels fused: 13.1 ± 3.8) were included. At baseline, 59% were compensating in LE: 32% at hips, 39% knees, and 36% ankles. After correction, 61% were compensating at least one joint. Patients undercorrected postoperatively were less likely to relieve LE compensation (odds ratio: 0.2, P = .037). Patients compensating in LE were more often undercorrected in age-adjusted pelvic tilt, pelvic incidence, lumbar lordosis, and T1 pelvic angle and disproportioned in Global Alignment and Proportion (P < .05). Patients matched in sagittal age-adjusted score at 6 weeks but compensating in LE were more likely to develop proximal junctional kyphosis (odds ratio: 4.1, P = .009) and proximal junctional failure (8% vs 0%, P = .035) than those sagittal age-adjusted score-matched and not compensating in LE. CONCLUSION: Perioperative lower extremity compensation was a product of undercorrecting complex ASD. Even in age-adjusted realignment, compensation was associated with global undercorrection and junctional failure. Consideration of lower extremities during planning is vital to avoid adverse outcomes in perioperative course after complex ASD surgery.

The Case for Operative Efficiency in Adult Spinal Deformity Surgery: Impact of Operative Time on Complications, Length of Stay, Alignment, Fusion Rates, and Patient-Reported Outcomes.

STUDY DESIGN: Retrospective review of prospectively collected data. OBJECTIVE: To analyze the impact of operative room (OR) time in adult spinal deformity (ASD) surgery on patient outcomes. BACKGROUND: It is currently unknown if OR time in ASD patients matched for deformity severity and surgical invasiveness is associated with patient outcomes. MATERIALS AND METHODS: ASD patients with baseline and two-year postoperative radiographic and patient-reported outcome measures (PROM) data, undergoing a posterior-only approach for long fusion (>L1-Ilium) were included. Patients were grouped into short OR time (<40th percentile: <359 min) and long OR time (>60th percentile: >421 min). Groups were matched by age, baseline deformity severity, and surgical invasiveness. Demographics, radiographic, PROM data, fusion rate, and complications were compared between groups at baseline and two years follow-up. RESULTS: In total, 270 patients were included for analysis: the mean OR time was 286 minutes in the short OR group versus 510 minutes in the long OR group ( P <0.001). Age, gender, percent of revision cases, surgical invasiveness, pelvic incidence minus lumbar lordosis, sagittal vertical axis, and pelvic tilt were comparable between groups ( P >0.05). Short OR had a slightly lower body mass index than the short OR group ( P <0.001) and decompression was more prevalent in the long OR time ( P =0.042). Patients in the long group had greater hospital length of stay ( P =0.02); blood loss ( P <0.001); proportion requiring intensive care unit ( P =0.003); higher minor complication rate ( P =0.001); with no significant differences for major complications or revision procedures ( P >0.5). Both groups had comparable radiographic fusion rates ( P =0.152) and achieved improvement in sagittal alignment measures, Oswestry disability index, and Short Form-36 ( P <0.001). CONCLUSION: Shorter OR time for ASD correction is associated with a lower minor complication rate, a lower estimated blood loss, fewer intensive care unit admissions, and a shorter hospital length of stay without sacrificing alignment correction or PROMs. Maximizing operative efficiency by minimizing OR time in ASD surgery has the potential to benefit patients, surgeons, and hospital systems.

Inflation-adjusted medicare physician reimbursement for adult spinal deformity surgery substantially declined from 2002 to 2020.

PURPOSE: Physician fees for orthopaedic surgeons by the Centers for Medicare and Medicaid Services (CMS) are increasingly scrutinized. The present retrospective review aims to assess whether adult spinal deformity (ASD) surgeries are properly valued for Medicare reimbursement. METHODS: Current Procedural Terminology (CPT) codes related to posterior fusion of spinal deformity of ≤ 6, 7-12, and ≥ 13 vertebral levels, as well as additional arthrodesis and osteotomy levels, were assessed for (1) Compound annual growth rate (CAGR) from 2002 to 2020, calculated using physician fee data from the CMS Physician Fee Schedule Look-Up Tool; and (2) work relative value units (RVUs) per operative minute, using data from the National Surgical Quality Improvement Program. RESULTS: From 2002 to 2020, all CPT codes for ASD surgery had negative inflation-adjusted CAGRs (range, - 18.49% to - 27.66%). Mean physician fees for spinal fusion declined by 26.02% (CAGR, - 1.66%) in ≤ 6-level fusion, 27.91% (CAGR, - 1.80%) in 7- to 12-level fusion, and 28.25% (CAGR, - 1.83%) ≥ 13-level fusion. Fees for both 7-12 (P < 0.00001) and ≥ 13 levels (P < 0.00001) declined more than those for fusion of ≤ 6 vertebral levels. RVU per minute was lower for 7- to 12-level and ≥ 13-level (P < 0.00001 for both) ASD surgeries than for ≤ 6-level. CONCLUSIONS: Reimbursement for ASD surgery declined overall. CAGR for fusions of ≥ 7 levels were lower than those for fusions of ≤ 6 levels. For 2012-2018, ≥ 7-level fusions had lower RVU per minute than ≤ 6-level fusions. Revaluation of Medicare reimbursement for longer-level ASD surgeries may be warranted. LEVEL OF EVIDENCE: III.

Predicting major complications and discharge disposition after adult spinal deformity surgery.

BACKGROUND CONTEXT: Several spine-specific comorbidity indices are available to help risk-stratify patients before they undergo invasive spine procedures. Studies of patients with adult spinal deformity (ASD) typically use the Charlson Comorbidity Index (CCI), which is not specific to spine patients. PURPOSE: To compare the CCI with the Seattle Spine Score (SSS), the Adult Spinal Deformity-Comorbidity Score (ASD-CS), and the Modified 5-Item Frailty Index (mFI-5) and identify which tool more accurately predicted major perioperative complications and discharge disposition after ASD surgery. STUDY DESIGN/SETTING: Retrospective review. PATIENT SAMPLE: Patients with ASD who underwent spinal arthrodesis of at least four levels at a single institution. OUTCOME MEASURES: Self-reported measures include SSS, ASD-CS, and mFI-5. Functional measures include the CCI. METHODS: We retrospectively reviewed records of 164 patients with ASD who underwent spinal arthrodesis of ≥ four levels from January 2008 to February 2018 at our U.S. academic tertiary care center and who had available Oswestry Disability Index values. To assess the predictive ability of the comorbidity indices, we created five multivariable logistic regression models, with the presence of major complications and discharge disposition (home or inpatient rehabilitation) as the primary outcome variables. The base model used validated demographic and surgical factors that were predictors of complications and outcomes in those with ASD and within the broader spinal literature. The other four models used the base model along with one of the four indices. The predictive ability of each model was compared using goodness-of-fit testing, with higher pseudo-R2 values and lower Akaike information criteria (AIC) values indicating better model fit. RESULTS: Thirty-one patients (19%) experienced major perioperative complications, and 68 (42%) were discharged to inpatient rehabilitation facilities (vs home). The model using the SSS had the highest pseudo-R2 value and lowest AIC value for both major complications and discharge disposition. The mFI-5 had a similar predictive ability. The models using the CCI and ASD-CS were weaker predictors. CONCLUSIONS: Compared with the CCI and the ASD-CS, the SSS and the mFI-5 were strong predictors of major complications and discharge disposition after ASD surgery. These results suggest that the SSS and the mFI-5 are preferable to the CCI for clinical risk stratification and outcomes research in patients undergoing ASD surgery.

Cost Benefit of Implementation of Risk Stratification Models for Adult Spinal Deformity Surgery.

STUDY DESIGN/SETTING: Retrospective cohort study. OBJECTIVE: Assess the extent to which defined risk factors of adverse events are drivers of cost-utility in spinal deformity (ASD) surgery. METHODS: ASD patients with 2-year (2Y) data were included. Tertiles were used to define high degrees of frailty, sagittal deformity, blood loss, and surgical time. Cost was calculated using the Pearl Diver registry and cost-utility at 2Y was compared between cohorts based on the number of risk factors present. Statistically significant differences in cost-utility by number of baseline risk factors were determined using ANOVA, followed by a generalized linear model, adjusting for clinical site and surgeon, to assess the effects of increasing risk score on overall cost-utility. RESULTS: By 2 years, 31% experienced a major complication and 23% underwent reoperation. Patients with ≤2 risk factors had significantly less major complications. Patients with 2 risk factors improved the most from baseline to 2Y in ODI. Average cost increased by $8234 per risk factor (R2 = .981). Cost-per-QALY at 2Y increased by $122,650 per risk factor (R2 = .794). Adjusted generalized linear model demonstrated a significant trend between increasing risk score and increasing cost-utility (r2 = .408, P < .001). CONCLUSIONS: The number of defined patient-specific and surgical risk factors, especially those with greater than two, were associated with increased index surgical costs and diminished cost-utility. Efforts to optimize patient physiology and minimize surgical risk would likely reduce healthcare expenditures and improve the overall cost-utility profile for ASD interventions.Level of evidence: III.

Are We Focused on the Wrong Early Postoperative Quality Metrics? Optimal Realignment Outweighs Perioperative Risk in Adult Spinal Deformity Surgery.

BACKGROUND: While reimbursement is centered on 90-day outcomes, many patients may still achieve optimal, long-term outcomes following adult spinal deformity (ASD) surgery despite transient short-term complications. OBJECTIVE: Compare long-term clinical success and cost-utility between patients achieving optimal realignment and suboptimally aligned peers. STUDY DESIGN/SETTING: Retrospective cohort study of a prospectively collected multicenter database. METHODS: ASD patients with two-year (2Y) data included. Groups were propensity score matched (PSM) for age, frailty, body mass index (BMI), Charlson Comorbidity Index (CCI), and baseline deformity. Optimal radiographic criteria are defined as meeting low deformity in all three (Scoliosis Research Society) SRS-Schwab parameters or being proportioned in Global Alignment and Proportionality (GAP). Cost-per-QALY was calculated for each time point. Multivariable logistic regression analysis and ANCOVA (analysis of covariance) adjusting for baseline disability and deformity (pelvic incidence (PI), pelvic incidence minus lumbar lordosis (PI-LL)) were used to determine the significance of surgical details, complications, clinical outcomes, and cost-utility. RESULTS: A total of 930 patients were considered. Following PSM, 253 "optimal" (O) and 253 "not optimal" (NO) patients were assessed. The O group underwent more invasive procedures and had more levels fused. Analysis of complications by two years showed that the O group suffered less overall major (38% vs. 52%, p = 0.021) and major mechanical complications (12% vs. 22%, p = 0.002), and less reoperations (23% vs. 33%, p = 0.008). Adjusted analysis revealed O patients more often met MCID (minimal clinically important difference) in SF-36 PCS, SRS-22 Pain, and Appearance. Cost-utility-adjusted analysis determined that the O group generated better cost-utility by one year and maintained lower overall cost and costs per QALY (both p < 0.001) at two years. CONCLUSIONS: Fewer late complications (mechanical and reoperations) are seen in optimally aligned patients, leading to better long-term cost-utility overall. Therefore, the current focus on avoiding short-term complications may be counterproductive, as achieving optimal surgical correction is critical for long-term success.

The ISSG-AO Complication Intervention Score, but Not Major/Minor Designation, is Correlated With Length of Stay Following Adult Spinal Deformity Surgery.

STUDY DESIGN: Retrospective review. OBJECTIVES: The International Spine Study Group-AO (ISSG-AO) Adult Spinal Deformity (ASD) Complication Classification System was developed to improve classification, reporting, and study of complications among patients undergoing ASD surgery. The ISSG-AO system classifies interventions to address complications by level of invasiveness: grade zero (none); grade 1, mild (e.g., medication change); grade 2, moderate (e.g., ICU admission); grade 3, severe (e.g., reoperation related to surgery of interest). To evaluate the efficacy of the ISSG-AO ASD Complication Classification System, we aimed to compare correlations between postoperative length of stay (LOS) and complication severity as classified by the ISSG-AO ASD and traditional major/minor complication classification systems. METHODS: Patients age ≥18 in a multicenter ASD database who sustained in-hospital complications were identified. Complications were classified with the major/minor and ISSG-AO systems and correlated with LOS using an ensemble-based machine learning algorithm (conditional random forest) and a generalized linear mixed model. RESULTS: 490 patients at 19 sites were included. 64.9% of complications were major, and 35.1% were minor. By ISSG-AO classification, 20.4%, 66.1%, 6.7%, and 6.7% were grades 0-3, respectively. ISSG-AO complication grading demonstrated significant correlation with LOS, whereas major/minor complication classification demonstrated inverse correlation with LOS. In conditional random forest analysis, ISSG-AO classification had the greatest relative importance when assessing correlations across multiple variables with LOS. CONCLUSIONS: The ISSG-AO system may help identify specific complications associated with prolonged LOS. Targeted interventions to avoid or reduce these complications may improve ASD surgical quality and resource utilization.

Abnormal Postoperative PROMIS Scores are Associated with Patient Satisfaction in Adult Spinal Deformity and Degenerative Spine Patients.

STUDY DESIGN: Retrospective review. OBJECTIVES: To evaluate 1) patient satisfaction after adult spine surgery; 2) associations between number of abnormal PROMIS domain scores and postoperative satisfaction; and 3) associations between normalization of a patient's worst preoperative PROMIS domain score and postoperative satisfaction. SUMMARY OF BACKGROUND DATA: Although "legacy" patient-reported outcome measures correlate with patient satisfaction after adult spine surgery, it is unclear whether PROMIS scores do. METHODS: We included 1119 patients treated operatively for degenerative spine disease (DSD) or adult spinal deformity (ASD) from 2014-2019 at our tertiary hospital who completed questionnaires preoperatively and at ≥1 postoperative timepoints up to 2 years. Postoperative satisfaction was measured in ASD patients using items 21 and 22 from the SRS 22-revised questionnaire and in DSD patients using the NASS Patient Satisfaction Index. "Worst" preoperative PROMIS domain was that with the greatest clinically negative deviation from the mean. "Normalization" was a postoperative score within 1 standard deviation of the general population mean. Multivariate logistic regression identified factors associated with satisfaction. RESULTS: Satisfaction was reported by 88% of DSD and 86% of ASD patients at initial postoperative follow-up; this proportion did not change during the first year after surgery. We observed an inverse relationship between postoperative satisfaction and number of abnormal PROMIS domains at all postoperative timepoints beyond 6 weeks. Only among ASD patients was normalization of the worst preoperative PROMIS domain associated with greater odds of satisfaction at all timepoints up to 1 year. CONCLUSION: The proportion of DSD and ASD patients satisfied postoperatively did not change from 6 weeks to 1 year. Normalizing the worst preoperative PROMIS domain and minimizing the number of abnormal postoperative PROMIS scores may reduce the number of dissatisfied patients. PROMIS data can guide perioperative patient management to improve satisfaction. LEVEL OF EVIDENCE: 3.

The impact of baseline cervical malalignment on the development of proximal junctional kyphosis following surgical correction of thoracolumbar adult spinal deformity.

OBJECTIVE: The objective of this study was to identify the effect of baseline cervical deformity (CD) on proximal junctional kyphosis (PJK) and proximal junctional failure (PJF) in patients with adult spinal deformity (ASD). METHODS: This study was a retrospective analysis of a prospectively collected, multicenter database comprising ASD patients enrolled at 13 participating centers from 2009 to 2018. Included were ASD patients aged > 18 years with concurrent CD (C2-7 kyphosis < -15°, T1S minus cervical lordosis > 35°, C2-7 sagittal vertical axis > 4 cm, chin-brow vertical angle > 25°, McGregor's slope > 20°, or C2-T1 kyphosis > 15° across any three vertebrae) who underwent surgery. Patients were grouped according to four deformity classification schemes: Ames and Passias CD modifiers, sagittal morphotypes as described by Kim et al., and the head versus trunk balance system proposed by Mizutani et al. Mean comparison tests and multivariable binary logistic regression analyses were performed to assess the impact of these deformity classifications on PJK and PJF rates up to 3 years following surgery. RESULTS: A total of 712 patients with concurrent ASD and CD met the inclusion criteria (mean age 61.7 years, 71% female, mean BMI 28.2 kg/m2, and mean Charlson Comorbidity Index 1.90) and underwent surgery (mean number of levels fused 10.1, mean estimated blood loss 1542 mL, and mean operative time 365 minutes; 70% underwent osteotomy). By approach, 59% of the patients underwent a posterior-only approach and 41% underwent a combined approach. Overall, 277 patients (39.1%) had PJK by 1 year postoperatively, and an additional 189 patients (26.7%) developed PJK by 3 years postoperatively. Overall, 65 patients (9.2%) had PJF by 3 years postoperatively. Patients classified as having a cervicothoracic deformity morphotype had higher rates of early PJK than flat neck deformity and cervicothoracic deformity patients (p = 0.020). Compared with the head-balanced patients, trunk-balanced patients had higher rates of PJK and PJF (both p < 0.05). Examining Ames modifier severity showed that patients with moderate and severe deformity by the horizontal gaze modifier had higher rates of PJK (p < 0.001). CONCLUSIONS: In patients with concurrent cervical and thoracolumbar deformities undergoing isolated thoracolumbar correction, the use of CD classifications allows for preoperative assessment of the potential for PJK and PJF that may aid in determining the correction of extending fusion levels.

Height Gain Following Correction of Adult Spinal Deformity.

BACKGROUND: Height gain following a surgical procedure for patients with adult spinal deformity (ASD) is incompletely understood, and it is unknown if height gain correlates with patient-reported outcome measures (PROMs). METHODS: This was a retrospective cohort study of patients undergoing ASD surgery. Patients with baseline, 6-week, and subanalysis of 1-year postoperative full-body radiographic and PROM data were examined. Correlation analysis examined relationships between vertical height differences and PROMs. Regression analysis was utilized to preoperatively estimate T1-S1 and S1-ankle height changes. RESULTS: This study included 198 patients (mean age, 57 years; 69% female); 147 patients (74%) gained height. Patients with height loss, compared with those who gained height, experienced greater increases in thoracolumbar kyphosis (2.81° compared with -7.37°; p < 0.001) and thoracic kyphosis (12.96° compared with 4.42°; p = 0.003). For patients with height gain, sagittal and coronal alignment improved from baseline to postoperatively: 25° to 21° for pelvic tilt (PT), 14° to 3° for pelvic incidence - lumbar lordosis (PI-LL), and 60 mm to 17 mm for sagittal vertical axis (SVA) (all p < 0.001). The full-body mean height gain was 7.6 cm, distributed as follows: sella turcica-C2, 2.9 mm; C2-T1, 2.8 mm; T1-S1 (trunk gain), 3.8 cm; and S1-ankle (lower-extremity gain), 3.3 cm (p < 0.001). T1-S1 height gain correlated with the thoracic Cobb angle correction and the maximum Cobb angle correction (p = 0.002). S1-ankle height gain correlated with the corrections in PT, PI-LL, and SVA (p < 0.001). T1-ankle height gain correlated with the corrections in PT (p < 0.001) and SVA (p = 0.03). Trunk height gain correlated with improved Scoliosis Research Society (SRS-22r) Appearance scores (r = 0.20; p = 0.02). Patient-Reported Outcomes Measurement Information System (PROMIS) Depression scores correlated with S1-ankle height gain (r = -0.19; p = 0.03) and C2-T1 height gain (r = -0.18; p = 0.04). A 1° correction in a thoracic scoliosis Cobb angle corresponded to a 0.2-mm height gain, and a 1° correction in a thoracolumbar scoliosis Cobb angle resulted in a 0.25-mm height gain. A 1° improvement in PI-LL resulted in a 0.2-mm height gain. CONCLUSIONS: Most patients undergoing ASD surgery experienced height gain following deformity correction, with a mean full-body height gain of 7.6 cm. Height gain can be estimated preoperatively with predictive ratios, and height gain was correlated with improvements in reported SRS-22r appearance and PROMIS scores. LEVEL OF EVIDENCE: Therapeutic Level III . See Instructions for Authors for a complete description of levels of evidence.

Sarcopenia as a Risk Factor for Complications Following Pedicle Subtraction Osteotomy.

STUDY DESIGN: Retrospective cohort. OBJECTIVE: The objective was to determine if sarcopenia is an independent risk factor for complications in adult spinal deformity (ASD) patients undergoing pedicle subtraction osteotomy (PSO) and define categories of complication risk by sarcopenia severity. SUMMARY OF BACKGROUND DATA: Sarcopenia is linked to morbidity and mortality in several orthopedic procedures. Data concerning sarcopenia in ASD surgery is limited, particularly with respect to complex techniques performed such as PSO. With the high surgical burden of PSOs, appropriate patient selection is critical for minimizing complications. METHODS: We identified 73 ASD patients with lumbar CT/MRI scans who underwent PSO with spinal fusion ≥5 levels at a tertiary care center from 2005 to 2014. Sarcopenia was assessed by the psoas-lumbar vertebral index (PLVI). Using stratum-specific likelihood ratio analysis, patients were separated into 3 sarcopenia groups by complication risk. The primary outcome measure was any 2-year complication. Secondary outcome measures included intraoperative blood loss and length of stay. RESULTS: The mean PLVI was 0.84±0.28, with 47% of patients having complications. Patients with a complication had a 27% lower PLVI on average than those without complications (0.76 vs. 0.91, P=0.021). Stratum-specific likelihood ratio analysis produced 3 complication categories: 32% complication rate for PLVI ≥ 0.81; 61% for PLVI 0.60-0.80; and 69% for PLVI < 0.60. Relative to patients with PLVI ≥ 0.81, those with PLVI 0.60-0.80 and PLVI < 0.60 had 3.2× and 4.3× greater odds of developing a complication (P<0.05). For individual complications, patients with PLVI < 1.0 had a significantly higher risk of proximal junctional kyphosis (34% vs. 0%, P=0.022), while patients with PLVI < 0.8 had a significantly higher risk of wound infection (12% vs. 0%, P=0.028) and dural tear (14% vs. 0%, P=0.019). There were no significant associations between sarcopenia, intraoperative blood loss, and length of stay. CONCLUSIONS: The increasing severity of sarcopenia is associated with a significantly and incrementally increased risk of complications following ASD surgery that require PSO. LEVEL OF EVIDENCE: Level III.

Predicting 30-day mortality after surgery for metastatic disease of the spine: the H2-FAILS score.

PURPOSE: Scoring systems for metastatic spine disease focus on predicting long- to medium-term mortality or a combination of perioperative morbidity and mortality. However, accurate prediction of perioperative mortality alone may be the most important factor when considering surgical intervention. We aimed to develop and evaluate a new tool, the H2-FAILS score, to predict 30-day mortality after surgery for metastatic spine disease. METHODS: Using the National Surgical Quality Improvement Program database, we identified 1195 adults who underwent surgery for metastatic spine disease from 2010 to 2018. Incidence of 30-day mortality was 8.7% (n = 104). Independent predictors of 30-day mortality were used to derive the H2-FAILS score. H2-FAILS is an acronym for: Heart failure (2 points), Functional dependence, Albumin deficiency, International normalized ratio elevation, Leukocytosis, and Smoking (1 point each). Discrimination was assessed using area under the receiver operating characteristic curve (AUC). The H2-FAILS score was compared with the American Society of Anesthesiologists Physical Status Classification (ASA Class), the 5-item modified Frailty Index (mFI-5), and the New England Spinal Metastasis Score (NESMS). Internal validation was performed using bootstrapping. Alpha = 0.05. RESULTS: Predicted 30-day mortality was 1.8% for an H2-FAILS score of 0 and 78% for a score of 6. AUC of the H2-FAILS was 0.77 (95% confidence interval: 0.72-0.81), which was higher than the mFI-5 (AUC 0.58, p < 0.001), ASA Class (AUC 0.63, p < 0.001), and NESMS (AUC 0.70, p = 0.004). Internal validation showed an optimism-corrected AUC of 0.76. CONCLUSIONS: The H2-FAILS score accurately predicts 30-day mortality after surgery for spinal metastasis. LEVEL OF EVIDENCE: Prognostic level III.