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Purpose: Understanding the mechanism and extent of preoperative deformity in revision procedures may provide data to prevent future failures in lumbar spinal fusion patients., Methods: ASD patients without prior spine surgery (PRIMARY) and with prior short (SHORT) and long (LONG) fusions were included. SHORT patients were stratified into modes of failure: implant, junctional, malalignment, and neurologic. Baseline demographics, spinopelvic alignment, offset from alignment targets, and patient-reported outcome measures (PROMs) were compared across PRIMARY and SHORT cohorts. Segmental lordosis analyses, assessing under-, match, or over-correction to segmental and global lordosis targets, were performed by SRS-Schwab coronal curve type and construct length., Results: Among 785 patients, 430 (55%) were PRIMARY and 355 (45%) were revisions. Revision procedures included 181 (23%) LONG and 174 (22%) SHORT corrections. SHORT modes of failure included 27% implant, 40% junctional, 73% malalignment, and/or 28% neurologic. SHORT patients were older, frailer, and had worse baseline deformity (PT, PI-LL, SVA) and PROMs (NRS, ODI, VR-12, SRS-22) compared to primary patients (p < 0.001). Segmental lordosis analysis identified 93%, 88%, and 62% undercorrected patients at LL, L1-L4, and L4-S1, respectively. SHORT patients more often underwent 3-column osteotomies (30% vs. 12%, p < 0.001) and had higher ISSG Surgical Invasiveness Score (87.8 vs. 78.3, p = 0.006)., Conclusions: Nearly half of adult spinal deformity surgeries were revision fusions. Revision short fusions were associated with sagittal malalignment, often due to undercorrection of segmental lordosis goals, and frequently required more invasive procedures. Further initiatives to optimize alignment in lumbar fusions are needed to avoid costly and invasive deformity corrections., Level of Evidence: IV: Diagnostic: individual cross-sectional studies with consistently applied reference standard and blinding., Competing Interests: Declarations. Conflicts of interest: The authors declare that they have no conflicts of interest related to this paper., (© 2024. The Author(s), under exclusive licence to Springer-Verlag GmbH Germany, part of Springer Nature.)

Objective: The objective of this study was to identify baseline patient and surgical factors predictive of optimal outcomes in staged versus same-day combined-approach surgery., Methods: Adult spinal deformity (ASD) patients with baseline and perioperative (by 6 weeks) data were stratified based on single-stage (same-day) or multistage (staged) surgery, excluding planned multiple hospitalizations. Means comparison analyses were used to assess baseline demographic, radiographic, and surgical differences between cohorts. Backstep logistic regression and conditional inference tree analysis were used to identify variable thresholds associated with study-specific definitions of an optimal outcome in each cohort, defined as no intraoperative or surgery-related in-hospital adverse event., Results: There were 439 patients with complex ASD in the dataset (mean age 64.0 ± 9.3 years, 68% female, mean BMI 28.7 ± 5.5 kg/m2). Overall, 58.8% of patients were in the same-day group, while 41.2% were in the staged group. Demographically, cohorts were not significantly different (p > 0.05), but staged patients were more frail per total Edmonton Frail Scale score (p = 0.043). Staged patients also reported greater numeric rating scale scores for back pain than same-day patients (p = 0.002). Cohorts were comparable in magnitude of planned correction of C7-S1 sagittal vertical axis, pelvic incidence-lumbar lordosis (PI-LL) mismatch, and T4-12 kyphosis (all p > 0.05). Controlling for baseline age, frailty, and number of levels fused, staged patients reported significantly higher PROMIS Discretionary Social Activities scores by 6 weeks (p = 0.029). Radiographic outcomes by 6 weeks were comparable between cohorts, in terms of both magnitude of change from baseline and overall result (all p > 0.05). Same-day patients were significantly more likely to experience in-hospital complications (p = 0.013). When considering frailty thresholds for staging, only a Charlson Comorbidity Index ≤ 1.0 was associated with optimal outcome in same-day patients, while Edmonton Frail Scale score ≥ 7 (p = 0.036), ≥ 9 levels fused (p = 0.016), and baseline PI-LL mismatch ≥ 15.3° (p = 0.028) were associated with optimal outcome for staged patients. Yet, staging alone was not significantly associated with an optimal outcome perioperatively (p = 0.056)., Conclusions: While staged and same-day combined-approach surgeries yield comparable radiographic and patient-reported outcomes, certain subsets of complex ASD patients may benefit from staged surgery despite the invariably increased hospital length of stay. Individuals with increased frailty, moderate to severe PI-LL mismatch, and increased anticipated number of levels fused may experience a lower risk of perioperative adverse events if they undergo a staged procedure. Clinical trial registration no.: NCT04194138 (ClinicalTrials.gov).

Study Design: Retrospective analysis of prospectively collected data., Objective: This study evaluates the impact of knee osteoarthritis (OA) and knee arthroplasty on alignments and patient-reported outcomes measures (PROMS) of patients undergoing adult spinal deformity (ASD) corrective surgery., Background: The relationship between knee OA and spinal alignment in patients with ASD is incompletely understood. It is also unknown how patients with knee arthroplasty and ASD compare to ASD patients with native knees., Methods: Baseline full-body radiographs were used, and hip and knee OA were graded by two independent reviewers using the KL classification. Spinopelvic parameters and PROMs were compared across the different knee OA groups and compared between patients with knee replacement and native knees., Results: 199 patients with bilateral non severe OA (G1), 31 patients with unilateral severe knee OA (G2), and 60 patients with bilateral severe knee OA (G3). Patients with severe knee OA presented with worse spinopelvic parameters. However, after multivariable regression analysis controlling for age, frailty, PI, T1PA, knee OA was an independent predictor of knee flexion (G1:-0.02±7.3, G2: 7.8±9.4, G3: 4.5±8.7, P<0.001), and ankle dorsiflexion (G1: 2.3±4.0, G2: 6.6±4.5, G3: 5.1±4.1, P<0.001). There was no difference in PROMs (P>0.05). Secondary analysis included 96 patients: 48 patients (50%) with non-severe knee OA, and 48 patients (50%) with knee replacement. There was no difference in radiographic parameters or PROMs between the groups., Conclusion: In this study of complex ASD patients, patients with worse spinal deformity were more likely to have concomitant knee OA. Knee OA was shown to be a predictor of knee flexion and ankle dorsiflexion angles, but was not associated with worse PROMs in this study population. Patients with knee arthroplasty, however, had comparable spinal alignment and PROMs relative to those with mild OA., Competing Interests: The authors report no conflicts of interest., (Copyright © 2024 Wolters Kluwer Health, Inc. All rights reserved.)

Purpose: To investigate the impact of the Global Alignment and Proportion (GAP) score components on patient outcomes in Adult Spine Deformity (ASD) surgery., Methods: Patients included underwent assessment via the GAP score and its individual components: pelvic version (GAP PV), lumbar lordosis (GAP LL), lumbar distribution index (GAP LDI) and spinopelvic component (GAP SP). Multivariable analyses assessed the association between alignment in these components and clinical outcomes in ASD patients., Results: 762 ASD patients met inclusion criteria. Alignment in GAP SP independently predicted meeting MCID for SR-22S and ODI and was associated with a lower likelihood of developing mechanical complications. Patients aligned in GAP SP were less likely to develop proximal junctional kyphosis (OR 0.42, 0.26-0.73, p = 0.01) and PJF (OR 0.3, 0.13-0.74, p = 0.01). Proportioned alignment in GAP SP with disproportioned alignment in GAP LDI contributed to an increased risk of PJK and PJF (OR 2.67, 95% CI 1.95-6.82, p = 0.045). There was no significant association of GAP SP proportionality and GAP RPV (OR 1.1, 0.86-2.15, p = 0.253) or GAP LL (OR 1.34, 0.78-4.23, p = 0.673) disproportionality with outcomes. Disproportioned alignment in GAP SP but proportioned alignment in both GAP LL and GAP LDI was associated with decreased likelihood of PJK (OR 0.53, 95% CI 0.39-0.94, p = 0.02) and PJF (OR 0.31, 95% CI 0.19-0.67, p = 0.001)., Conclusion: The spinopelvic component of the GAP score is the most significant independent predictor of clinical outcomes. Its interaction with the other components of the GAP score also aids assessment of the risk for mechanical complications., (© 2024. The Author(s), under exclusive licence to Springer-Verlag GmbH Germany, part of Springer Nature.)

Background and Objectives: For patients with surgical adult spinal deformity (ASD), our understanding of alignment has evolved, especially in the last 20 years. Determination of optimal restoration of alignment and spinal shape has been increasingly studied, yet the assessment of how these alignment schematics have incrementally added benefit to outcomes remains to be evaluated., Methods: Patients with ASD with baseline and 2-year were included, classified by 4 alignment measures: Scoliosis Research Society (SRS)-Schwab, Age-Adjusted, Roussouly, and Global Alignment and Proportion (GAP). The incremental benefits of alignment schemas were assessed in chronological order as our understanding of optimal alignment progressed. Alignment was considered improved from baseline based on SRS-Schwab 0 or decrease in severity, Age-Adjusted ideal match, Roussouly current (based on sacral slope) matching theoretical (pelvic incidence-based), and decrease in proportion. Patients separated into 4 first improving in SRS-Schwab at 2-year, second Schwab improvement and matching Age-Adjusted, third two prior with Roussouly, and fourth improvement in all four. Comparison was accomplished with means comparison tests and χ 2 analyses., Results: Sevenhundredthirty-two. patients met inclusion. SRS-Schwab BL: pelvic incidence-lumbar lordosis mismatch (++:32.9%), sagittal vertical axis (++: 23%), pelvic tilt (++:24.6%). 640 (87.4%) met criteria for first, 517 (70.6%) second, 176 (24%) third, and 55 (7.5%) fourth. The addition of Roussouly (third) resulted in lower rates of mechanical complications and proximal junctional kyphosis (48.3%) and higher rates of meeting minimal clinically important difference (MCID) for physical component summary and SRS-Mental ( P < .05) compared with the second. Fourth compared with the third had higher rates of MCID for ODI (44.2% vs third: 28.3%, P = .011) and SRS-Appearance (70.6% vs 44.8%, P < .001). Mechanical complications and proximal junctional kyphosis were lower with the addition of Roussouly ( P = .024), while the addition of GAP had higher rates of meeting MCID for SRS-22 Appearance ( P = .002) and Oswestry Disability Index ( P = .085)., Conclusion: Our evaluation of the incremental benefit that alignment schemas have provided in ASD corrective surgery suggests that the addition of Roussouly provided the greatest reduction in mechanical complications, while the incorporation of GAP provided the most significant improvement in patient-reported outcomes., (Copyright © Congress of Neurological Surgeons 2024. All rights reserved.)

Study Design: Retrospective cohort study., Objectives: To evaluate whether different radiographic clusters of adult spinal deformity identified using artificial intelligence-based clustering are associated with distinct surgical outcomes., Methods: Patients were classified based on the results of a previously conducted analysis that examined clusters of deformity, including Moderate Sagittal (Mod Sag), Severe Sagittal (Sev Sag), Coronal, and Hyper-Thoracic Kyphosis (Hyper-TK). The surgical data, HRQOL, and complication outcomes of these clusters were then compared., Results: The final analysis included 1062 patients. Similar to published results on a different patient sample, Mod Sag and Sev Sag patients were older, more likely to have a history of previous spine surgery, and more disabled. By 2-year, all clusters improved in HRQOL and reached a similar rate of minimal clinically important difference (MCID).The Sev Sag cluster had the highest rate major complications (53% vs 34-40%), and complications leading to reoperation (29% vs 17-23%), implant failures (20% vs 8-11%), and operative complications (27% vs 10-17%). Coronal patients had the highest rate of pulmonary complications (9% vs 3-6%) but the lowest rate of X-ray imbalance (10% vs 19-21%). No significant differences were found in neurological complications, infection rate, gastrointestinal, or cardiac events (all P > .1). Kaplan-Meier survival curves demonstrated a lower time to first complications for the Sev Sag cluster., Conclusions: All clusters of adult spinal deformity benefit similarly from surgery as they all achieved similar rates of MCID. Although the rates of complications varied among the clusters, the types of complications were not significantly different., Competing Interests: Declaration of Conflicting InterestsThe author(s) declared no potential conflicts of interest with respect to the research, authorship, and/or publication of this article.

Objective: The aim of this study was to provide benchmarks for the rates of complications by type of surgery performed., Study Design: Prospective multicenter database., Background: We have previously examined overall construct survival and complication rates for ASD surgery. However, the relationship between type of surgery and construct survival warrants more detailed assessment., Materials and Methods: Eight surgical scenarios were defined based on the levels treated, previous fusion status [primary (P) vs. revision (R)], and three-column osteotomy use (3CO): short lumbar fusion, LT-pelvis with 5 to 12 levels treated (P, R, or 3CO), UT-pelvis with 13 levels treated (P, R, or 3CO), and thoracic to lumbar fusion without pelvic fixation, representing 92.4% of the case in the cohort. Complication rates for each type were calculated and Kaplan-Meier curves with multivariate Cox regression analysis was used to evaluate the effect of the case characteristics on construct survival rate, while controlling for patient profile., Results: A total of 1073 of 1494 patients eligible for 2-year follow-up (71.8%) were captured. Survival curves for major complications (with or without reoperation), while controlling for demographics differed significantly among surgical types ( P <0.001). Fusion procedures short of the pelvis had the best survival rate, while UT-pelvis with 3CO had the worst survival rate. Longer fusions and more invasive operations were associated with lower 2-year complication-free survival, however, there were no significant associations between type of surgery and renal, cardiac, infection, wound, gastrointestinal, pulmonary, implant malposition, or neurological complications (all P >0.5)., Conclusions: This study suggests that there is an inherent increased risk of complication for some types of ASD surgery independent of patient profile. The results of this paper can be used to produce a surgery-adjusted benchmark for ASD surgery with regard to complications and survival. Such a tool can have very impactful applications for surgical decision-making and more informed patient counseling., Level of Evidence: Level III., Competing Interests: The authors report no conflicts of interest., (Copyright © 2024 Wolters Kluwer Health, Inc. All rights reserved.)

Study Design: Retrospective Cohort Study., Objectives: Length of Stay (LOS) and resource utilization are of primary importance for hospital administration. This study aimed to understand the incremental effect of having a specific complication on LOS among ASD patients., Methods: A retrospective examination of prospective multicenter data utilized patients without a complication prior to discharge to develop a patient-adjusted and surgery-adjusted predictive model of LOS among ASD patients. The model was later applied to patients with at least 1 complication prior to discharge to investigate incremental effect of each identified complication on LOS vs the expected LOS., Results: 571/1494 (38.2%) patients experienced at least 1 complication before discharge with a median LOS of 7 [IQR 5 to 9]. Univariate analysis demonstrated that LOS was significantly affected by patients' demographics (age, CCI, sex, disability, deformity) and surgical strategy (invasiveness, fusion length, posterior MIS fusion, direct decompression, osteotomy severity, IBF use, EBL, ASA, ICU stay, day between stages, Date of Sx). Using patients with at least 1 complication prior discharge and compared to the patient-and-surgery adjusted prediction, having a minor complication increased the expected LOS by 0.9 day(s), a major complication by 3.9 days, and a major complication with reoperation by 6.3 days., Conclusion: Complications following surgery for ASD correction have different, but predictable impact on LOS. Some complications requiring minimal intervention are associated with significant and substantial increases in LOS, while complications with significant impact on patient quality of life may have no influence on LOS., Competing Interests: Declaration of Conflicting InterestsThe author(s) declared no potential conflicts of interest with respect to the research, authorship, and/or publication of this article.

Background: Severe sagittal plane deformity with loss of L4-S1 lordosis is disabling and can be improved through various surgical techniques. However, data are limited on the differing ability of anterior lumbar interbody fusion (ALIF), pedicle subtraction osteotomy (PSO), and transforaminal lumbar interbody fusion (TLIF) to achieve alignment goals in severely malaligned patients., Methods: Severe adult spinal deformity patients with preoperative PI-LL >20°, L4-S1 lordosis <30°, and full body radiographs and PROMs at baseline and 6-week postoperative visit were included. Patients were grouped into ALIF (1-2 level ALIF at L4-S1), PSO (L4/L5 PSO), and TLIF (1-2 level TLIF at L4-S1). Comparative analyses were performed on demographics, radiographic spinopelvic parameters, complications, and PROMs., Results: Among the 96 included patients, 40 underwent ALIF, 27 underwent PSO, and 29 underwent TLIF. At baseline, cohorts had comparable age, sex, race, Edmonton frailty scores, and radiographic spinopelvic parameters (P > 0.05). However, PSO was performed more often in revision cases (P < 0.001). Following surgery, L4-S1 lordosis correction (P = 0.001) was comparable among ALIF and PSO patients and caudal lordotic apex migration (P = 0.044) was highest among ALIF patients. PSO patients had higher intraoperative estimated blood loss (P < 0.001) and motor deficits (P = 0.049), and in-hospital ICU admission (P = 0.022) and blood products given (P = 0.004), but were otherwise comparable in terms of length of stay, blood transfusion given, and postoperative admission to rehab. Likewise, 90-day postoperative complication profiles and 6-week PROMs were comparable as well., Conclusions: ALIF can restore L4-S1 sagittal alignment as powerfully as PSO, with fewer intraoperative and in-hospital complications. When feasible, ALIF is a suitable alternative to PSO and likely superior to TLIF for correcting L4-S1 lordosis among patients with severe sagittal malalignment., (Copyright © 2024 Elsevier Inc. All rights reserved.)

Study Design: Retrospective analysis of prospectively collected data., Objective: Evaluate the impact of correcting normative segmental lordosis values on postoperative outcomes., Background: Restoring lumbar lordosis magnitude is crucial in adult spinal deformity surgery, but the optimal location and segmental distribution remain unclear., Patients and 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 undercorrected and overcorrected. Surgical technique, patient-reported outcome measures, and surgical complications were compared across groups at baseline and two years., Results: In total, 510 patients with a mean age of 64.6, a mean Charlson comorbidity index 2.08, and a mean 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 Oswestry disability index 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 (U: 16.0% vs. M: 15.6% vs. O: 32.8%, P <0.001) and had greater posterior inclination of the upper instrumented vertebrae (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 proximal junctional failure with overcorrection and increased rates of implant failure with undercorrection based on normative segmental lordosis., Level of Evidence: Level IV., Competing Interests: The authors report no conflicts of interest., (Copyright © 2024 Wolters Kluwer Health, Inc. All rights reserved.)

Study Design: Multicenter, prospective cohort., Objectives: Malalignment following adult spine deformity (ASD) surgery can impact outcomes and increase mechanical complications. We assess whether preoperative goals for sagittal alignment following ASD surgery are achieved., Methods: ASD patients were prospectively enrolled based on 3 criteria: deformity severity (PI-LL ≥25°, TPA ≥30°, SVA ≥15 cm, TCobb≥70° or TLCobb≥50°), procedure complexity (≥12 levels fused, 3-CO or ACR) and/or age (>65 and ≥7 levels fused). The surgeon documented sagittal alignment goals prior to surgery. Goals were compared with achieved alignment on first follow-up standing radiographs., Results: The 266 enrolled patients had a mean age of 61.0 years (SD = 14.6) and 68% were women. Mean instrumented levels was 13.6 (SD = 3.8), and 23.2% had a 3-CO. Mean (SD) offsets (achieved-goal) were: SVA = -8.5 mm (45.6 mm), PI-LL = -4.6° (14.6°), TK = 7.2° (14.7°), reflecting tendencies to undercorrect SVA and PI-LL and increase TK. Goals were achieved for SVA, PI-LL, and TK in 74.4%, 71.4%, and 68.8% of patients, respectively, and was achieved for all 3 parameters in 37.2% of patients. Three factors were independently associated with achievement of all 3 alignment goals: use of PACs/equivalent for surgical planning ( P < .001), lower baseline GCA ( P = .009), and surgery not including a 3-CO ( P = .037)., Conclusions: Surgeons failed to achieve goal alignment of each sagittal parameter in ∼25-30% of ASD patients. Goal alignment for all 3 parameters was only achieved in 37.2% of patients. Those at greatest risk were patients with more severe deformity. Advancements are needed to enable more consistent translation of preoperative alignment goals to the operating room., Competing Interests: Declaration of Conflicting InterestsThe author(s) declared the following potential conflicts of interest with respect to the research, authorship, and/or publication of this article: reports consultancy fees from ZimVie, NuVasive, Cerapedics, and Carlsmed; receives royalties from Zimmer Biomet and Nuvasive; holds stock in Alphatec and NuVasive; receives research funding to his institution from DePuy Synthes, International Spine Study Group Foundation (ISSGF), and AOSpine; receives fellowship grant funding to his institution from AOSpine; serves on the Executive Committee of the ISSGF; and serves on the editorial boards of Journal of Neurosurgery Spine, Neurosurgery, Operative Neurosurgery, and Spine Deformity. is a consultant for ISSGF. is a consultant for Globus Medical and Alphatec; receives royalties from NuVasive; receives research support from ISSG; receives honoraria from DePuy Synthes, Stryker, and Implanet; and has leadership roles in ISSG and the Scoliosis Research Society. is a consultant for DePuy Synthes, Stryker, and Medtronic, SI Bone, and Agnovos; receives honoraria and a fellowship grant paid to an institution from AO Spine; and has leadership roles with AOSpine. Dr. Kim receives royalties from Zimmer Biomet, Acuity Surgical, and K2M-Stryker; is a consultant for NuVasive; receives research support from the ISSGF; is on advisory boards for Vivex Biology and Aspen Medical; and has other financial or non-financial interests with AOSpine. is a consultant for Medtronic, SpineWave, Terumo, and Royal Biologics; receives honoraria from Cervical Spine Research Society, Globus Medical, and Zimmer; serves on the editorial or governing board for Spine journal; and receives research support from Allosource. receives research support from Stryker, Biom’Up, Pfizer, the Alan L. & Jacqueline B. Stuart Spine Center, National Health Foundation, Cerapedics, Empirical Spine, Inc., TSRH, and Scoliosis Research Society; receives royalties from Acuity, Medtronic, and NuVasive; is a consultant for Acuity, DePuy, Medtronic, NuVasive, FYR Medical, and Stryker; receives honoraria from Baxter, Broadwater, NASS, and Pacira Pharmaceuticals; holds patents with Medtronic; participates on a data safety monitoring board or advisory board with Medtronic; has a leadership role in the National Spine Health Foundation; owns stock/stock options in Cingulate Therapeutics and FYR Medical; is an employee of Norton Healthcare, Inc.; and serves as a journal reviewer for Global Spine Journal, Spine Deformity, and The Spine Journal. and receives research/fellowship support from NuVasive, Medtronic, SeaSpine, SI Bone, and AONA; receives royalties from SI Bone, Nuvasive, Seaspine, Aesculap, and Globus Medical; is a consultant for Aesculap, NuVasive, SI Bone, SeaSpine, Spinal Elements, Biedermann-Motech, Silony, Neo Medical, Depuy, Medtronic, Carevature, and ControlRad; has received payment/honoraria from Radius; has patents with Globus, Spine Innovation, and SI Bone; has leadership role with San Diego Spine Foundation; and has stock/stock options with Alphatec, Nuvasive, Seaspine, and SI Bone. receives grants/research support from Medtronic and Orthofix; receives royalties from Spineart and Stryker; is a consultant for Stryker Spine, Spineart, and Medtronic; and has received payment for expert testimony from multiple law firms. is a consultant for NuVasive, Viseon, Carlsmed, SI Bone, and SeaSpine; holds patents with Stryker, NuVasive, and SeaSpine; has leadership roles with Global Spine Outreach and San Diego Spine Foundation; has stock or stock options with Alphatec, SeaSpine, and NuVasive; and receives royalties from NuVasive and K2M/Stryker. is a consultant for Globus, NuVasive, and Medtronic; receives royalties from Altus; receives grants from Medtronic; and has stock or stock options from One Point Surgical. Dr. receives travel expenses to teach at the ISSG-Medtronic Spine Course for fellows and residents; and has a leadership role with the Canadian Spine Society. receives grants/research support from Prosydiuan and NuVasive. receives honoraria from Wolters Kluwer; received support for travel from AO Spine; has leadership roles with Scoliosis Research Society and AO Spine; and receives research support from the Setting Scoliosis Straight Foundation and San Diego Spine Foundation. is a consultant for Stryker Spine; receives grant/research support from Medtronic, DePuy Synthes, and AOSpine; receives honoraria from Medtronic, Stryker Spine, DePuy Synthes, Scoliosis Research Society, and AOSpine; receives support for travel from AO Spine and Scoliosis Research Society; and is on an advisory board/panel for AOSpine Research Commission and Scoliosis Research Society Research Task Force; and is Chair of the AO Spine Knowledge Forum Deformity. owns stock in J&J; is a consultant for DePuy, Medtronic, Globus; receives royalties from Innomed, DePuy, and Globus; receives honoraria from AO Spine, Wright State, and LSU; serves on the board of directors of the Scoliosis Research Society; receives travel reimbursements from DePuy, Globus, Scoliosis Research Society; and has a voluntary relationship with the National Spine Health Foundation. is a consultant for MSD, Zimmer Biomet, and Mainstay Medical; receives royalties from Zimmer Biomet, Medtronic, and Stryker; owns stock in VFT Solutions and SeaSpine; is an executive committee member of ISSG. receives royalties from DePuy Spine, Globus, and Blue Ocean Spine; is a consultant for DePuy Spine, Globus, and Blue Ocean Spine; has a leadership role in the Scoliosis Research Society and International Spine Study Group Foundation; has stock or stock options in Progenerative Medical; and has received research support from DePuy Spine and ISSGF. receives royalties from Stryker, Biomet Zimmer Spine, DePuy Synthes, NuVasive, Next Orthosurgical, K2M, and Medicrea; is a consultant for DePuy Synthes, Medtronic, Medicrea, K2M, Agada Medical, and Carlsmed; receives research support from Titan Spine, DePuy Synthes, and ISSG; serves on the editorial board of Operative Neurosurgery; receives grant funding from SRS; serves on the executive committee of ISSG; is the director of Global Spinal Analytics; and is the safety and value committee chair of SRS. is a consultant for Medtronic, ABRYX, and Acuity Surgical; receives research/grant support from AOSpine, Scoliosis Research Society, and Setting Scoliosis Straight Foundation; receives royalties from Medtronic and Acuity Surgical; and receives other financial support from Broadwater, AOSpine, and Scoliosis Research Society. is a consultant for NuVasive, SI Bone, and Proprio; owns stock in NuVasive; holds patents with NuVasive; receives fellowship funding from Globus, Medtronic, and NuVasive; and receives royalties from NuVasive, Medtronic, and SI Bone; has leadership roles with SRS and CSRS; and receives study-related clinical or research support from DePuy Synthes and ISSGF. is a consultant for Zimmer Biomet, NuVasive, Cerapedics, Carlsmed, SeaSpine, and DePuy Synthes; owns stock in Alphatec and NuVasive; receives study-related clinical or research support from DePuy Synthes and ISSGF; receives non–study-related clinical or research support from DePuy Synthes, ISSGF, and AO Spine; receives royalties from Zimmer Biomet and NuVasive; and receives fellowship support from AO Spine. is a consultant for Alphatec, Stryker, and MiRus; receives honoraria from Stryker; holds patents with Stryker; receives study-related clinical or research support from Medtronic, Globus, NuVasive, Stryker, Carlsmed, and SI Bone; receives non–study-related clinical or research support from DePuy Synthes; and receives royalties from Stryker and NuVasive. report no conflicts of interest.

Study Design: Retrospective analysis of prospectively collected data., Objective: Evaluate the impact of prior cervical constructs on upper instrumented vertebrae (UIV) selection and postoperative outcomes among patients undergoing thoracolumbar deformity correction., Background: Surgical planning for adult spinal deformity (ASD) patients involves consideration of spinal alignment and existing fusion constructs., Methods: ASD patients with (ANTERIOR or POSTERIOR) and without (NONE) prior cervical fusion who underwent thoracolumbar fusion were included. Demographics, radiographic alignment, patient-reported outcome measures (PROMs), and complications were compared. Univariate and multivariate analyses were performed on POSTERIOR patients to identify parameters predictive of UIV choice and to evaluate postoperative outcomes impacted by UIV selection., Results: Among 542 patients, with 446 NONE, 72 ANTERIOR, and 24 POSTERIOR patients, mean age was 64.4 years and 432 (80%) were female. Cervical fusion patients had worse preoperative cervical and lumbosacral deformity, and PROMs (P<0.05). In the POSTERIOR cohort, preoperative LIV was frequently below the cervicothoracic junction (54%) and uncommonly (13%) connected to the thoracolumbar UIV. Multivariate analyses revealed that higher preoperative cervical SVA (coeff=-0.22, 95%CI=-0.43--0.01, P=0.038) and C2SPi (coeff=-0.72, 95%CI=-1.36--0.07, P=0.031), and lower preoperative thoracic kyphosis (coeff=0.14, 95%CI=0.01-0.28, P=0.040) and thoracolumbar lordosis (coeff=0.22, 95%CI=0.10-0.33, P=0.001) were predictive of cranial UIV. Two-year postoperatively, cervical patients continued to have worse cervical deformity and PROMs (P<0.05) but had comparable postoperative complications. Choice of thoracolumbar UIV below or above T6, as well as the number of unfused levels between constructs, did not affect patient outcomes., Conclusions: Among patients who underwent thoracolumbar deformity correction, prior cervical fusion was associated with more severe spinopelvic deformity and PROMs preoperatively. The choice of thoracolumbar UIV was strongly predicted by their baseline cervical and thoracolumbar alignment. Despite their poor preoperative condition, these patients still experienced significant improvements in their thoracolumbar alignment and PROMs after surgery, irrespective of UIV selection., Level of Evidence: IV., Competing Interests: The authors report no conflicts of interest., (Copyright © 2024 Wolters Kluwer Health, Inc. All rights reserved.)

Background: Hip osteoarthritis (OA) is common in patients with adult spinal deformity (ASD). Limited data exist on the prevalence of hip OA in patients with ASD, or on its impact on baseline and postoperative alignment and patient-reported outcome measures (PROMs). Therefore, this paper will assess the prevalence and impact of hip OA on alignment and PROMs., Methods: Patients with ASD who underwent L1-pelvis or longer fusions were included. Two independent reviewers graded hip OA with the Kellgren-Lawrence (KL) classification and stratified it by severity into non-severe (KL grade 1 or 2) and severe (KL grade 3 or 4). Radiographic parameters and PROMs were compared among 3 patient groups: Hip-Spine (hip KL grade 3 or 4 bilaterally), Unilateral (UL)-Hip (hip KL grade 3 or 4 unilaterally), or Spine (hip KL grade 1 or 2 bilaterally)., Results: Of 520 patients with ASD who met inclusion criteria for an OA prevalence analysis, 34% (177 of 520) had severe bilateral hip OA and unilateral or bilateral hip arthroplasty had been performed in 8.7% (45 of 520). A subset of 165 patients had all data components and were examined: 68 Hip-Spine, 32 UL-Hip, and 65 Spine. Hip-Spine patients were older (67.9 ± 9.5 years, versus 59.6 ± 10.1 years for Spine and 65.8 ± 7.5 years for UL-Hip; p < 0.001) and had a higher frailty index (4.3 ± 2.6, versus 2.7 ± 2.0 for UL-Hip and 2.9 ± 2.0 for Spine; p < 0.001). At 1 year, the groups had similar lumbar lordosis, yet the Hip-Spine patients had a worse sagittal vertebral axis (SVA) measurement (45.9 ± 45.5 mm, versus 25.1 ± 37.1 mm for UL-Hip and 19.0 ± 39.3 mm for Spine; p = 0.001). Hip-Spine patients also had worse Veterans RAND-12 Physical Component Summary scores at baseline (25.7 ± 9.3, versus 28.7 ± 9.8 for UL-Hip and 31.3 ± 10.5 for Spine; p = 0.005) and 1 year postoperatively (34.5 ± 11.4, versus 40.3 ± 10.4 for UL-Hip and 40.1 ± 10.9 for Spine; p = 0.006)., Conclusions: This study of operatively treated ASD revealed that 1 in 3 patients had severe hip OA bilaterally. Such patients with severe bilateral hip OA had worse baseline SVA and PROMs that persisted 1 year following ASD surgery, despite correction of lordosis., Level of Evidence: Prognostic Level III. See Instructions for Authors for a complete description of levels of evidence., Competing Interests: Disclosure: Funding for this study was received from DePuy Synthes Spine, NuVasive, and K2/Stryker. In addition, the International Spine Study Group reports grants to the foundation from Medtronic, Globus, Stryker, SI Bone, and Carlsmed. The Disclosure of Potential Conflicts of Interest forms are provided with the online version of the article (http://links.lww.com/JBJS/H962)., (Copyright © 2024 by The Journal of Bone and Joint Surgery, Incorporated.)

Study Design: A retrospective cohort study of a prospectively collected multicenter adult spinal deformity (ASD) database., Objective: The aim of this study was to compare staged procedures to same-day interventions and identify the optimal time interval between staged surgeries for the treatment of ASD., Background: Surgical intervention for ASD is an invasive and complex procedure that surgeons often elect to perform on different days (staging). Yet, there remains a paucity of literature on the timing and effects of the interval between stages., Materials and Methods: ASD patients with 2-year data undergoing an anterior/posterior (A/P) fusion to the ilium were included. Propensity score matching was performed for the number of levels fused, number of interbody devices, surgical approaches, number of osteotomies/three-column osteotomy, frailty, Oswestry Disability Index, Charlson Comorbidity Index, revisions, sagittal vertical axis, pelvic incidence-lumbar lordosis, and upper instrumented vertebrae to create balanced cohorts of same-day and staged surgical patients. Staged patients were stratified by intervening time-period between surgeries, using quartiles., Results: A total of 176 propensity score-matched patients were included. The median interval between A/P staged procedures was 3 days. Staged patients had greater operative time and lower intensive care unit stays postoperatively ( P <0.05). At 2 years, staged compared with same-day showed a greater improvement in T1 slope-cervical lordosis, C2 sacral slope, and SRS-Schwab sagittal vertical axis ( P <0.05). Staged patients had higher rates of minimal clinically important difference for 1-year SRS-Appearance and 2-year Physical Component Summary scores. Assessing different intervals of staging, patients at the 75th percentile interval showed greater improvement in 1-year SRS-Pain and SRS-Total postoperative as well as SRS-Activity, Pain, Satisfaction, and Total scores ( P <0.05) compared with patients in lower quartiles. Compared with the 25th percentile, patients reaching the 50th percentile interval were associated with increased odds of improvement in Global Alignment and Proportion score proportionality [9.3 (1.6-53.2), P =0.01]., Conclusions: This investigation is among the first to compare multicenter staged and same-day surgery A/P ASD patients fused to ilium using propensity matching. Staged procedures resulted in significant improvement radiographically, reduced intensive care unit admissions, and superior patient-reported outcomes compared with same-day procedures. An interval of at least 3 days between staged procedures is associated with superior outcomes in terms of Global Alignment and Proportion score proportionality., Competing Interests: The authors report no conflicts of interest., (Copyright © 2023 Wolters Kluwer Health, Inc. All rights reserved.)

Objective: Provide benchmarks for the rates of complications by type and timing., Study Design: Prospective multicenter database., Background: Complication rates following adult spinal deformity (ASD) surgery have been previously reported. However, the interplay between timing and complication type warrants further analysis., Methods: The data for this study were sourced from a prospective, multicenter ASD database. The date and type of complication were collected and classified into three severity groups (minor, major, and major leading to reoperation). Only complications occurring before the two-year visit were retained for analysis., Results: Of the 1260 patients eligible for two-year follow-up, 997 (79.1%) achieved two-year follow-up. The overall complication rate was 67.4% (N=672). 247 patients (24.8%) experienced at least one complication on the day of surgery (including intraoperatively), 359 (36.0%) between postoperative day 1 and six weeks postoperatively, 271 (27.2%) between six weeks and one-year postoperatively, and finally 162 (16.3%) between one year and two years postoperatively. Using Kaplan-Meier survival analysis, the rate of remaining complication-free was estimated at different time points for different severities and types of complications. Stratification by type of complication demonstrated that most of the medical complications occurred within the first 60 days. Surgical complications presented over two distinct timeframes. Operative complications, incision-related complications, and infections occurred early (within 60 d), while implant-related and radiographic complications occurred at a constant rate over the two-year follow-up period. Neurological complications had the highest occurrence within the first 60 days but continued to increase up to the two-year visit., Conclusion: Only one-third of ASD patients remained complication-free by two years, and 2 of 10 patients had a complication requiring a reoperation or revision. An estimation of the timing and type of complications associated with surgical treatment may prove useful for more meaningful patient counseling and aid in assessing the cost-effectiveness of treatment., Level of Evidence: 3., Competing Interests: The authors report no conflicts of interest., (Copyright © 2024 Wolters Kluwer Health, Inc. All rights reserved.)

Background Context: Among adult spinal deformity (ASD) patients, heterogeneity in patient pathology, surgical expectations, baseline impairments, and frailty complicates comparisons in clinical outcomes and research. This study aims to qualitatively segment ASD patients using machine learning-based clustering on a large, multicenter, prospectively gathered ASD cohort., Purpose: To qualitatively segment adult spinal deformity patients using machine learning-based clustering on a large, multicenter, prospectively gathered cohort., Study Design/setting: Machine learning algorithm using patients from a prospective multicenter study and a validation cohort from a retrospective single center, single surgeon cohort with complete 2-year follow up., Patient Sample: About 805 ASD patients; 563 patients from a prospective multicenter study and 242 from a single center to be used as a validation cohort., Outcome Measures: To validate and extend the Ames-ISSG/ESSG classification using machine learning-based clustering analysis on a large, complex, multicenter, prospectively gathered ASD cohort., Methods: We analyzed a training cohort of 563 ASD patients from a prospective multicenter study and a validation cohort of 242 ASD patients from a retrospective single center/surgeon cohort with complete two-year patient-reported outcomes (PROs) and clinical/radiographic follow-up. Using k-means clustering, a machine learning algorithm, we clustered patients based on baseline PROs, Edmonton frailty, age, surgical history, and overall health. Baseline differences in clusters identified using the training cohort were assessed using Chi-Squared and ANOVA with pairwise comparisons. To evaluate the classification system's ability to discern postoperative trajectories, a second machine learning algorithm assigned the single-center/surgeon patients to the same 4 clusters, and we compared the clusters' two-year PROs and clinical outcomes., Results: K-means clustering revealed four distinct phenotypes from the multicenter training cohort based on age, frailty, and mental health: Old/Frail/Content (OFC, 27.7%), Old/Frail/Distressed (OFD, 33.2%), Old/Resilient/Content (ORC, 27.2%), and Young/Resilient/Content (YRC, 11.9%). OFC and OFD clusters had the highest frailty scores (OFC: 3.76, OFD: 4.72) and a higher proportion of patients with prior thoracolumbar fusion (OFC: 47.4%, OFD: 49.2%). ORC and YRC clusters exhibited lower frailty scores and fewest patients with prior thoracolumbar procedures (ORC: 2.10, 36.6%; YRC: 0.84, 19.4%). OFC had 69.9% of patients with global sagittal deformity and the highest T1PA (29.0), while YRC had 70.2% exhibiting coronal deformity, the highest mean coronal Cobb Angle (54.0), and the lowest T1PA (11.9). OFD and ORC had similar alignment phenotypes with intermediate values for Coronal Cobb Angle (OFD: 33.7; ORC: 40.0) and T1PA (OFD: 24.9; ORC: 24.6) between OFC (worst sagittal alignment) and YRC (worst coronal alignment). In the single surgeon validation cohort, the OFC cluster experienced the greatest increase in SRS Function scores (1.34 points, 95%CI 1.01-1.67) compared to OFD (0.5 points, 95%CI 0.245-0.755), ORC (0.7 points, 95%CI 0.415-0.985), and YRC (0.24 points, 95%CI -0.024-0.504) clusters. OFD cluster patients improved the least over 2 years. Multivariable Cox regression analysis demonstrated that the OFD cohort had significantly worse reoperation outcomes compared to other clusters (HR: 3.303, 95%CI: 1.085-8.390)., Conclusion: Machine-learning clustering found four different ASD patient qualitative phenotypes, defined by their age, frailty, physical functioning, and mental health upon presentation, which primarily determines their ability to improve their PROs following surgery. This reaffirms that these qualitative measures must be assessed in addition to the radiographic variables when counseling ASD patients regarding their expected surgical outcomes., Competing Interests: Declaration of Competing Interest One or more of the authors declare financial or professional relationships on ICMJE-TSJ disclosure forms., (Copyright © 2024 Elsevier Inc. All rights reserved.)

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., Patients and Methods: In total, 527 preoperative 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°, and 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 that with increasing T1PA, pelvic tilt correlated inversely with hip osteoarthritis and positively with knee osteoarthritis ( r2 =0.812). Hip osteoarthritis decreased compensation through sacrofemoral angle (β-coefficient=-0.206). Knee and hip osteoarthritis contributed to greater knee flexion (β-coefficients=0.215, 0.101; respectively). For pelvic shift, only hip osteoarthritis significantly contributed to the model (β-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., Competing Interests: The International Spine Study Group reports the following: grants to the foundation from Medtronic, Globus, Stryker, SI Bone, Carlsmed. The remaining authors report no conflicts of interest., (Copyright © 2024 Wolters Kluwer Health, Inc. All rights reserved.)

Study Design: Retrospective cohort., Objective: To examine the validity of the Oswestry Disability Index (ODI) in patients with adult spinal deformity (ASD) treated with surgery., Background: The ODI is a patient-reported outcome measure of low back pain and disability. Although nearly ubiquitous in ASD research, the measure has not been validated in this patient population., Patients and Methods: A registry of patients with ASD was queried for baseline and 1-year PROM data, including the ODI, the Scoliosis Research Society-22r (SRS-22r), and the Patient Reported Outcomes Measurement Information System-Pain Interference (PI) and Physical Function (PF) CATs. Internal reliability was assessed with Cronbach alpha, where values ≥0.7 are considered reliable. Validity was assessed with Spearman correlation coefficients calculated for the ODI against validated Patient-Reported Outcomes Measurement Information System (PROMIS)-PI and PF, and legacy measures SRS-Pain and SRS-Activity. Responsiveness to change was measured with the adjusted effect size., Results: A total of 325 patients were enrolled, with 208 completing baseline and 1-year patient-reported outcome measures. The majority (149, 72%) were females and White (193, 93%), median Charlson Comorbidity Index 0 (interquartile range: 0-2). The majority of cases included sagittal plane deformity [mean T1PA: 24.2° (13.9)]. Cronbach alpha showed excellent internal reliability (baseline = 0.89, 1 yr = 0.90). ODI was valid, with strong correlations between PROMIS-PI, PROMIS-PF, SRS-Pain, and SRS-Activity at baseline and 1-year follow-up. All measures were responsive to change, with the ODI showing greater responsiveness than PROMIS-PI, PROMIS-PF, and SRS-Activity., Conclusions: The ODI is a valid measure of disability as measured by pain and function in patients with ASD. It is responsive to change in a manner not different from validated PROMIS-CAT or the SRS-22r legacy measure. It is multidimensional, however, as it assesses both pain and function simultaneously. It does not measure disability related to self-image and may not account for all disease-related disability in patients with ASD., Competing Interests: The authors report no conflicts of interest., (Copyright © 2024 Wolters Kluwer Health, Inc. All rights reserved.)

Purpose: To develop a simplified, modified frailty index for adult spinal deformity (ASD) patients dependent on objective clinical factors., Methods: ASD patients with baseline (BL) and 2-year (2Y) follow-up were included. Factors with the largest R 2 value derived from multivariate forward stepwise regression were including in the modified ASD-FI (clin-ASD-FI). Factors included in the clin-ASD-FI were regressed against mortality, extended length of hospital stay (LOS, > 8 days), revisions, major complications and weights for the clin-ASD-FI were calculated via Beta/Sullivan. Total clin-ASD-FI score was created with a score from 0 to 1. Linear regression correlated clin-ASD-FI with ASD-FI scores and published cutoffs for the ASD-FI were used to create the new frailty cutoffs: not frail (NF: < 0.11), frail (F: 0.11-0.21) and severely frail (SF: > 0.21). Binary logistic regression assessed odds of complication or reop for frail patients., Results: Five hundred thirty-one ASD patients (59.5 yrs, 79.5% F) were included. The final model had a R 2 of 0.681, and significant factors were: < 18.5 or > 30 BMI (weight: 0.0625 out of 1), cardiac disease (0.125), disability employment status (0.3125), diabetes mellitus (0.0625), hypertension (0.0625), osteoporosis (0.125), blood clot (0.1875), and bowel incontinence (0.0625). These factors calculated the score from 0 to 1, with a mean cohort score of 0.13 ± 0.14. Breakdown by clin-ASD-FI score: 51.8% NF, 28.1% F, 20.2% SF. Increasing frailty severity was associated with longer LOS (NF: 7.0, F: 8.3, SF: 9.2 days; P < 0.001). Frailty independently predicted occurrence of any complication (OR: 9.357 [2.20-39.76], P = 0.002) and reop (OR: 2.79 [0.662-11.72], P = 0.162)., Conclusions: Utilizing an existing ASD frailty index, we proposed a modified version eliminating the patient-reported components. This index is a true assessment of physiologic status, and represents a superior risk factor assessment compared to other tools for both primary and revision spinal deformity surgery as a result of its immutability with surgery, lack of subjectivity, and ease of use., (© 2024. The Author(s), under exclusive licence to Scoliosis Research Society.)

Study Design: Retrospective review of a prospective multicenter adult spinal deformity (ASD) study., Objective: The aim of this study was to evaluate 30-day readmissions, 90-day return to surgery, postoperative complications, and patient-reported outcomes (PROs) for matched ASD patients receiving nonhome discharge (NON), including acute rehabilitation (REHAB), and skilled nursing facility (SNF), or home (HOME) discharge following ASD surgery., Summary of Background Data: Postoperative disposition following ASD surgery frequently involves nonhome discharge. Little data exists for longer term outcomes for ASD patients receiving nonhome discharge versus patients discharged to home., Materials and Methods: Surgically treated ASD patients prospectively enrolled into a multicenter study were assessed for NON or HOME disposition following hospital discharge. NON was further divided into REHAB or SNF. Propensity score matching was used to match for patient age, frailty, spine deformity, levels fused, and osteotomies performed at surgery. Thirty-day hospital readmissions, 90-day return to surgery, postoperative complications, and 1-year and minimum 2-year postoperative PROs were evaluated., Results: A total of 241 of 374 patients were eligible for the study. NON patients were identified and matched to HOME patients. Following matching, 158 patients remained for evaluation; NON and HOME had similar preoperative age, frailty, spine deformity magnitude, surgery performed, and duration of hospital stay ( P >0.05). Thirty-day readmissions, 90-day return to surgery, and postoperative complications were similar for NON versus HOME and similar for REHAB (N=64) versus SNF (N=42) versus HOME ( P >0.05). At 1-year and minimum 2-year follow-up, HOME demonstrated similar to better PRO scores including Oswestry Disability Index, Short-Form 36v2 questionnaire Mental Component Score and Physical Component Score, and Scoliosis Research Society scores versus NON, REHAB, and SNF ( P <0.05)., Conclusions: Acute needs must be considered following ASD surgery, however, matched analysis comparing 30-day hospital readmissions, 90-day return to surgery, postoperative complications, and PROs demonstrated minimal benefit for NON, REHAB, or SNF versus HOME at 1- and 2-year follow-up, questioning the risk and cost/benefits of routine use of nonhome discharge., Level of Evidence: Level III-prognostic., Competing Interests: The authors report no conflicts of interest., (Copyright © 2023 Wolters Kluwer Health, Inc. All rights reserved.)

Background: The objective of this study was to evaluate if imbalance influences complication rates, radiological outcomes, and patient-reported outcomes (PROMs) following adult spinal deformity (ASD) surgery. Methods: ASD patients with baseline and 2-year radiographic and PROMs were included. Patients were grouped according to whether they answered yes or no to a recent history of pre-operative loss of balance. The groups were propensity-matched by age, pelvic incidence-lumbar lordosis (PI-LL), and surgical invasiveness score. Results: In total, 212 patients were examined (106 in each group). Patients with gait imbalance had worse baseline PROM measures, including Oswestry disability index (45.2 vs. 36.6), SF-36 mental component score (44 vs. 51.8), and SF-36 physical component score ( p < 0.001 for all). After 2 years, patients with gait imbalance had less pelvic tilt correction (-1.2 vs. -3.6°, p = 0.039) for a comparable PI-LL correction (-11.9 vs. -15.1°, p = 0.144). Gait imbalance patients had higher rates of radiographic proximal junctional kyphosis (PJK) (26.4% vs. 14.2%) and implant-related complications (47.2% vs. 34.0%). After controlling for age, baseline sagittal parameters, PI-LL correction, and comorbidities, patients with imbalance had 2.2-times-increased odds of PJK after 2 years. Conclusions: Patients with a self-reported loss of balance/unsteady gait have significantly worse PROMs and higher risk of PJK.

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.

Objective: Complex spinal deformity surgeries may involve significant blood loss. The use of antifibrinolytic agents such as tranexamic acid (TXA) has been proven to reduce perioperative blood loss. However, for patients with a history of thromboembolic events, there is concern of increased risk when TXA is used during these surgeries. This study aimed to assess whether TXA use in patients undergoing complex spinal deformity correction surgeries increases the risk of thromboembolic complications based on preexisting thromboembolic risk factors., Methods: Data were analyzed for adult patients who received TXA during surgical correction for spinal deformity at 21 North American centers between August 2018 and October 2022. Patients with preexisting thromboembolic events and other risk factors (history of deep venous thrombosis [DVT], pulmonary embolism [PE], myocardial infarction [MI], stroke, peripheral vascular disease, or cancer) were identified. Thromboembolic complication rates were assessed during the postoperative 90 days. Univariate and multivariate analyses were performed to assess thromboembolic outcomes in high-risk and low-risk patients who received intravenous TXA., Results: Among 411 consecutive patients who underwent complex spinal deformity surgery and received TXA intraoperatively, 130 (31.6%) were considered high-risk patients. There was no significant difference in thromboembolic complications between patients with and those without preexisting thromboembolic risk factors in univariate analysis (high-risk group vs low-risk group: 8.5% vs 2.8%, p = 0.45). Specifically, there were no significant differences between groups regarding the 90-day postoperative rates of DVT (high-risk group vs low-risk group: 1.5% vs 1.4%, p = 0.98), PE (2.3% vs 1.8%, p = 0.71), acute MI (1.5% vs 0%, p = 0.19), or stroke (0.8% vs 1.1%, p > 0.99). On multivariate analysis, high-risk status was not a significant independent predictor for any of the thromboembolic complications., Conclusions: Administration of intravenous TXA during the correction procedure did not change rates of thromboembolic events, acute MI, or stroke in this cohort of adult spinal deformity surgery patients.

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., Competing Interests: The authors report no conflicts of interest., (Copyright © 2023 Wolters Kluwer Health, Inc. All rights reserved.)

Study Design: Retrospective review of prospective multicenter data., Objectives: This study aimed to investigate the shape of TK before and after fusion in ASD patients treated with long fusion., Methods: ASD patients undergoing posterior spinal fusions including at least T5 to L1 without prior fusion extending to the thoracic spine were included. Patients were categorized based on the preoperative T1-T12 kyphosis into: Hypo-TK (if < 30°), Normal-TK, and Hyper-TK (if > 70°). Regional kyphosis at T10-L1 (Distal), T5-T10 (Middle), and T1-T5 (Proximal) and their relative contributions to total kyphosis were compared between groups, and the pre-to postoperative changes were investigated using paired t test., Results: In total, 329 patients were included in this analysis (mean age: 57 ± 16 years, 79.6% female). Preoperative T1-T12 TK for the entire cohort was 40.9 ± 2° (32% Hypo-TK, 11% Hyper-TK, 57% Normal-TK). The Hypo-TK group had the smallest distal TK (5.9 vs 17.1 & 26.0), and middle TK (8.0 vs 25.3 & 45.4), but the percentage of contribution to total kyphosis was not significantly different (Distal: 24.1% vs 34.1% vs 32.8%; Middle: 46.6% vs 53.9% vs 56.8%, all P > .1). Postoperatively, T1-12 TK increased significantly (40.9 ± 2.0° vs 57.8 ± 17.6°). Each group had a decrease in distal kyphosis (Hypo-TK 2.6 ± 10.4°; Normal-TK 8.9 ± 11.5°; Hyper-TK 14.9 ± 12°, all P < .05). The middle kyphosis significantly decreased for Hyper-TK (11.8 ± 12.4) and increased for both Normal-TK and Hypo-TK (3.8 ± 11° and 14.2 ± 11°). Proximal TK increased significantly for all groups by 14-18°. Deterioration from Normal-TK to Hyper-TK postoperatively was associated with lower rate of patient satisfaction (59.6% vs 77.3%, P = .032)., Conclusions: Posterior spinal fusion for ASD alters the magnitude and shape of thoracic kyphosis. While 60% of patients had a normal TK at baseline, 30% of those patients developed iatrogenic hyperkyphosis postoperatively. Patients with baseline hypokyphosis were more likely to be corrected to normal TK than hyperkyphotic patients. Future research should investigate TK restoration in ASD and its impact on clinical outcomes and complications., Competing Interests: Declaration of Conflicting InterestsThe author(s) declared no potential conflicts of interest with respect to the research, authorship, and/or publication of this article.

Study Design: Retrospective cohort study., Objective: Understand the benefit of addressing malalignment in revision surgery for proximal junctional kyphosis (PJK)., Summary of Background Data: PJK is a common cause of revision surgery for adult spinal deformity patients. During a revision, surgeons may elect to perform a proximal extension of the fusion, or also correct the source of the lumbopelvic mismatch., Materials and Methods: Recurrent PJK following revision surgery was the primary outcome. Revision surgical strategy was the primary predictor (proximal extension of fusion alone compared with combined sagittal correction and proximal extension). Multivariable logistic regression determined rates of recurrent PJK between the two surgical groups with lumbopelvic surgical correction assessed through improving ideal alignment in one or more alignment criteria [Global Alignment and Proportionality (GAP), Roussouly-type, and Sagittal Age-Adjusted Score (SAAS)]., Results: A total of 151 patients underwent revision surgery for PJK. PJK occurred at a rate of 43.0%, and PJF at 12.6%. Patients proportioned in GAP postrevision had lower rates of recurrent PJK [23% vs. 42%; odds ratio (OR): 0.3, 95% confidence interval (CI): 0.1-0.8, P =0.024]. Following adjusted analysis, patients who were ideally aligned in one of three criteria (Matching in SAAS and/or Roussouly matched and/or achieved GAP proportionality) had lower rates of recurrent PJK (36% vs. 53%; OR: 0.4, 95% CI: 0.1-0.9, P =0.035) and recurrent PJF (OR: 0.1, 95% CI: 0.02-0.7, P =0.015). Patients ideally aligned in two of three criteria avoid any development of PJF (0% vs. 16%, P <0.001)., Conclusions: Following revision surgery for PJK, patients with persistent poor sagittal alignment showed increased rates of recurrent PJK compared with patients who had abnormal lumbopelvic alignment corrected during the revision. These findings suggest addressing the root cause of surgical failure in addition to proximal extension of the fusion may be beneficial., Competing Interests: The authors report no conflicts of interest., (Copyright © 2022 Wolters Kluwer Health, Inc. All rights reserved.)

Study Design: Multicenter comparative cohort., Objective: Studies have shown markedly higher rates of complications and all-cause mortality following surgery for adult cervical deformity (ACD) compared with adult thoracolumbar deformity (ATLD), though the reasons for these differences remain unclear. Our objectives were to compare baseline frailty, disability, and comorbidities between ACD and complex ATLD patients undergoing surgery., Methods: Two multicenter prospective adult spinal deformity registries were queried, one ATLD and one ACD. Baseline clinical and frailty measures were compared between the cohorts., Results: 616 patients were identified (107 ACD and 509 ATLD). These groups had similar mean age (64.6 vs 60.8 years, respectively, P = .07). ACD patients were less likely to be women (51.9% vs 69.5%, P < .001) and had greater Charlson Comorbidity Index (1.5 vs .9, P < .001) and ASA grade (2.7 vs 2.4, P < .001). ACD patients had worse VR-12 Physical Component Score (PCS, 25.7 vs 29.9, P < .001) and PROMIS Physical Function Score (33.3 vs 35.3, P = .031). All frailty measures were significantly worse for ACD patients, including hand dynamometer (44.6 vs 55.6 lbs, P < .001), CSHA Clinical Frailty Score (CFS, 4.0 vs 3.2, P < .001), and Edmonton Frailty Scale (EFS, 5.15 vs 3.21, P < .001). Greater proportions of ACD patients were frail (22.9% vs 5.7%) or vulnerable (15.6% vs 10.9%) based on EFS ( P < .001)., Conclusions: Compared with ATLD patients, ACD patients had worse baseline characteristics on all measures assessed (comorbidities/disability/frailty). These differences may help account for greater risk of complications and all-cause mortality previously observed in ACD patients and facilitate strategies for better preoperative optimization., Competing Interests: Declaration of Conflicting InterestsThe author(s) declared no potential conflicts of interest with respect to the research, authorship, and/or publication of this article.

Study Design: Retrospective review of a prospectively enrolled adult spinal deformity (ASD) database., Objective: To investigate what patient factors elevate the risk of sub-optimal outcomes after deformity correction., Background: Currently, it is unknown what factors predict a poor outcome after adult spinal deformity surgery, which may require increased preoperative consideration and counseling., Materials and Methods: Patients >18 yrs undergoing surgery for ASD(scoliosis≥20°, SVA≥5 cm, PT≥25°, or TK≥60°). An unsatisfactory outcome was defined by the following categories met at two years: (1) clinical: deteriorating in ODI at two years follow-up (2) complications/reoperation: having a reoperation and major complication were deemed high risk for poor outcomes postoperatively (HR). Multivariate analyses assessed predictive factors of HR patients in adult spinal deformity patients., Results: In all, 633 adult spinal deformity (59.9 yrs, 79% F, 27.7 kg/m 2, CCI: 1.74) were included. Baseline severe Schwab modifier incidence (++): 39.2% pelvic incidence and lumbar lordosis, 28.8% sagittal vertical axis, 28.9% PT. Overall, 15.5% of patients deteriorated in ODI by two years, while 7.6% underwent reoperation and had a major complication. This categorized 11 (1.7%) as HR. HR were more comorbid in terms of arthritis (73%), heart disease (36%), and kidney disease (18%), P <0.001. Surgically, HR had greater EBL (4431ccs) and underwent more osteotomies (91%), specifically Ponte(36%) and Three Column Osteotomies(55%), which occurred more at L2(91%). HR underwent more PLIFs (45%) and had more blood transfusion units (2641ccs), all P <0.050. The multivariate regression determined a combination of a baseline Distress and Risk Assessment Method score in the 75th percentile, having arthritis and kidney disease, a baseline right lower extremity motor score ≤3, cSVA >65 mm, C2 slope >30.2°, CTPA >5.5° for an R2 value of 0.535 ( P <0.001)., Conclusions: When addressing adult spine deformities, poor outcomes tend to occur in severely comorbid patients with major baseline psychological distress scores, poor neurologic function, and concomitant cervical malalignment., Competing Interests: P.G.P.: Cerapedics: Other financial or material support; Cervical Scoliosis Research Society: Research support; Globus Medical: Paid presenter or speaker; Medtronic: Paid consultant; Royal Biologics: Paid consultant; Spine: Editorial or governing board; Spinevision: Other financial or material support; SpineWave: Paid consultant; Terumo: Paid consultant; The remaining authors report no conflicts of interest., (Copyright © 2023 Wolters Kluwer Health, Inc. All rights reserved.)

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., Competing Interests: Disclosure: The Disclosure of Potential Conflicts of Interest forms are provided with the online version of the article ( http://links.lww.com/JBJS/H620 )., (Copyright © 2023 The Authors. Published by The Journal of Bone and Joint Surgery, Incorporated. All rights reserved.)

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., Competing Interests: Declaration of Conflicting InterestsThe author(s) declared no potential conflicts of interest with respect to the research, authorship, and/or publication of this article.

Objective: The purpose of this study was to investigate the cost utility of nonoperative treatment for adult spinal deformity (ASD)., Methods: Nonoperatively and operatively treated patients who met database criteria for ASD and in whom complete radiographic and health-related quality of life data at baseline and at 2 years were available were included. A cost analysis was completed on the PearlDiver database assessing the average cost of nonoperative treatment prior to surgical intervention based on previously published treatments (NSAIDs, narcotics, muscle relaxants, epidural steroid injections, physical therapy, and chiropractor). Utility data were calculated using the Oswestry Disability Index (ODI) converted to SF-6D with published conversion methods. Quality-adjusted life years (QALYs) used a 3% discount rate to account for residual decline in life expectancy (78.7 years). Minor and major comorbidities and complications were assessed according to the CMS.gov manual's definitions. Successful nonoperative treatment was defined as a gain in the minimum clinically importance difference (MCID) in both ODI and Scoliosis Research Society (SRS)-pain scores, and failure was defined as a loss in MCID or conversion to operative treatment. Patients with baseline ODI ≤ 20 and continued ODI of ≤ 20 at 2 years were considered nonoperative successful maintenance. The average utilization of nonoperative treatment and cost were applied to the ASD cohort., Results: A total of 824 patients were included (mean age 58.24 years, 81% female, mean body mass index 27.2 kg/m2). Overall, 75.5% of patients were in the operative and 24.5% were in the nonoperative cohort. At baseline patients in the operative cohort were significantly older, had a greater body mass index, increased pelvic tilt, and increased pelvic incidence-lumbar lordosis mismatch (all p < 0.05). With respect to deformity, patients in the operative group had higher rates of severe (i.e., ++) sagittal deformity according to SRS-Schwab modifiers for pelvic tilt, sagittal vertical axis, and pelvic incidence-lumbar lordosis mismatch (p < 0.05). At 2 years, patients in the operative cohort showed significantly increased rates of a gain in MCID for physical component summary of SF-36, ODI, and SRS-activity, SRS-pain, SRS-appearance, and SRS-mental scores. Cost analysis showed the average cost of nonoperative treatment 2 years prior to surgical intervention to be $2041. Overall, at 2 years patients in the nonoperative cohort had again in ODI of 0.36, did not show a gain in QALYs, and nonoperative treatment was determined to be cost-ineffective. However, a subset of patients in this cohort underwent successful maintenance treatment and had a decrease in ODI of 1.1 and a gain in utility of 0.006 at 2 years. If utility gained for this cohort was sustained to full life expectancy, patients' cost per QALY was $18,934 compared to a cost per QALY gained of $70,690.79 for posterior-only and $48,273.49 for combined approach in patients in the operative cohort., Conclusions: Patients with ASD undergoing operative treatment at baseline had greater sagittal deformity and greater improvement in health-related quality of life postoperatively compared to patients treated nonoperatively. Additionally, patients in the nonoperative cohort overall had an increase in ODI and did not show improvement in utility gained. Patients in the nonoperative cohort who had low disability and sagittal deformity underwent successful maintenance and cost-effective treatment.

Study Design: Retrospective cohort study., Objective: Investigate the patterns of fused lumbar alignment in patients requiring revision surgery for proximal junctional kyphosis (PJK)., Methods: Fifty patients (67.8 yo, 76% female) with existing thoraco-lumbar fusion (T10/12 to pelvis) and indicated for surgical correction for PJK were included. To investigate patterns of radiographic alignment prior to PJK revision, unsupervised 2-step cluster analysis was run on parameters describing the fused lumbar spine (PI-LL) to identify natural independent groups within the cohort. Clusters were compared in terms of demographics, pre-operative alignment, surgical parameters, and post-operative alignment. Associations between pre- and post-revision PJK angles were investigated using a Pearson correlation analysis., Results: Analysis identified 2 distinct patterns: Under-corrected (UC, n = 12, 32%) vs over-corrected (OC, n = 34, 68%) with a silhouette of .5. The comparison demonstrated similar pelvic incidence (PI) and PJK angle but significantly greater deformity for the UC vs OC group in terms of PI-LL, PI-LL offset, pelvic tilt, and sagittal vertebral axis. The surgical strategy for PJK correction did not differ between the 2 groups in terms of approach, American Society of Anesthesiologists grade, decompression, use of osteotomy, interbody fusion, or fusion length. The post-revision PJK angle significantly correlated with the amount of PJK correction within the OC group but not within the UC group., Conclusions: This study identified 2 patterns of lumbar malalignment associated with severe PJK: over vs under corrected. Despite the difference in PJK etiology, both patterns underwent the same revision strategy. Future analysis should look at the effect of correcting focal deformity alone vs correcting focal deformity and underlying malalignment simultaneously on recurrent PJK rate.

Objective: The authors of this study sought to evaluate the predictive role of global sagittal alignment and upper instrumented vertebra (UIV) level in symptomatic proximal junctional kyphosis (PJK) among patients with adult spinal deformity (ASD)., Methods: Data on ASD patients who had undergone fusion of ≥ 5 vertebrae from 2008 to 2018 and with a minimum follow-up of 1 year were obtained from a prospectively collected multicenter database and evaluated (n = 1312). Radiographs were obtained preoperatively and at 6 weeks, 6 months, 1 year, 2 years, and 3 years postoperatively. The 22-Item Scoliosis Research Society Patient Questionnaire Revised (SRS-22r) scores were collected preoperatively, 1 year postoperatively, and 2 years postoperatively. Symptomatic PJK was defined as a kyphotic increase > 20° in the Cobb angle from the UIV to the UIV+2. At 6 weeks postoperatively, sagittal parameters were evaluated and patients were categorized by global alignment and proportion (GAP) score/category and SRS-Schwab sagittal modifiers. Patients were stratified by UIV level: upper thoracic (UT) UIV ≥ T8 or lower thoracic (LT) UIV ≤ T9., Results: Patients who developed symptomatic PJK (n = 260) had worse 1-year postoperative SRS-22r mental health (3.70 vs 3.86) and total (3.56 vs 3.67) scores, as well as worse 2-year postoperative self-image (3.45 vs 3.65) and satisfaction (4.03 vs 4.22) scores (all p ≤ 0.04). In the whole study cohort, patients with PJK had less pelvic incidence-lumbar lordosis (PI-LL) mismatch (-0.24° vs 3.29°, p < 0.001) but no difference in their GAP score/category or SRS-Schwab sagittal modifiers compared with the patients without PJK. Regression showed a higher risk of PJK with a pelvic tilt (PT) grade ++ (OR 2.35) and less risk with a PI-LL grade ++ (OR 0.35; both p < 0.01). When specifically analyzing the LT UIV cohort, patients with PJK had a higher GAP score (5.66 vs 4.79), greater PT (23.02° vs 20.90°), and less PI-LL mismatch (1.61° vs 4.45°; all p ≤ 0.02). PJK patients were less likely to be proportioned postoperatively (17.6% vs 30.0%, p = 0.015), and regression demonstrated a greater PJK risk with severe disproportion (OR 1.98) and a PT grade ++ (OR 3.15) but less risk with a PI-LL grade ++ (OR 0.45; all p ≤ 0.01). When specifically evaluating the UT UIV cohort, the PJK patients had less PI-LL mismatch (-2.11° vs 1.45°) but no difference in their GAP score/category. Regression showed a greater PJK risk with a PT grade + (OR 1.58) and a decreased risk with a PI-LL grade ++ (OR 0.21; both p < 0.05)., Conclusions: Symptomatic PJK leads to worse patient-reported outcomes and is associated with less postoperative PI-LL mismatch and greater postoperative PT. A worse postoperative GAP score and disproportion are only predictive of symptomatic PJK in patients with an LT UIV.

Background: Adult spinal deformity (ASD) surgery can improve patient pain and physical function but is associated with high complication rates and long postoperative recovery. Accordingly, if given a choice, patients may indicate they would not undergo ASD surgery again., Purpose: Evaluate surgically treated ASD patients to assess if given the option (1) would surgically treated ASD patients choose to undergo the same ASD surgery again, (2) would the treating surgeon perform the same ASD surgery again and if not why, (3) evaluate for consensus and/or discrepancies between patient and surgeon opinions for willingness to perform/receive the same surgery, and (4) evaluate for associations with willingness to undergo or not undergo the same surgery again and patient demographics, patient reported outcomes, and postoperative complications., Study Design: Retrospective review of a prospective ASD study., Patient Sample: Surgically treated ASD patients enrolled into a multicenter prospective study., Outcome Measures: Scoliosis Research Society-22r questionnaire (SRS-22r), Short Form-36v2 questionnaire (SF-36) physical component summary (PCS) and mental component summary (MCS), Oswestry Disability Index (ODI), numeric pain rating for back pain (NRS back) and leg pain (NRS leg), minimal clinically important difference (MCID) for SRS-22r domains and ODI, intraoperative and postoperative complications, surgeon and patient satisfaction with surgery., Methods: Surgically treated ASD patients prospectively enrolled into a multicenter study were asked at minimum 2-year postoperative, if, based upon their hospital and surgical experiences and surgical recovery experiences, would the patient undergo the same surgery again. Treating surgeons were then matched to their corresponding patients, blinded to the patients' preoperative and postoperative patient reported outcome measures, and interviewed and asked if (1) the surgeon believed that the corresponding patient would undergo the surgery again, (2) if the surgeon believed the corresponding patient was improved by the surgery and (3) if the surgeon would perform the same surgery on the corresponding patient again, and if not why. ASD patients were divided into those indicating they would (YES), would not (NO) or were unsure (UNSURE) if they would have same surgery again. Agreement between patient and surgeon willingness to receive/perform the same surgery was assessed and correlations between patient willingness for same surgery, postoperative complications, spine deformity correction, patient reported outcomes (PROs)., Results: A total of 580 of 961 ASD patients eligible for study were evaluated. YES (n=472) had similar surgical procedures performed, similar duration of hospital and ICU stay, similar spine deformity correction and similar postoperative spinal alignment as NO (n=29; p>.05). UNSURE (n=79) had greater preoperative depression and opioid use rates, UNSURE and NO had more postoperative complications requiring surgery, and UNSURE and NO had fewer percentages of patients reaching postoperative MCID for SRS-22r domains and MCID for ODI than YES (p<.05). Comparison of patient willingness to receive the same surgery versus surgeon perceptions on patient's willingness to receive the same surgery demonstrated surgeons accurately identified YES (91.1%) but poorly identified NO (13.8%; p<.05)., Conclusions: If given a choice, 18.6% of surgically treated ASD patients indicated they were unsure or would not undergo the surgery again. ASD patients indicating they were unsure or would not undergo ASD surgery again had greater preoperative depression, greater preoperative opioid use, worse postoperative PROs, fewer patients reaching MCID, more complications requiring surgery, and greater postoperative opioid use. Additionally, patients that indicated they would not have the same surgery again were poorly identified by their treating surgeons compared to patients indicating they would be willing to receive the same surgery again. More research is needed to understand patient expectations and improve patient experiences following ASD surgery., Competing Interests: Declaration of competing interest One or more of the authors declare financial or professional relationships on ICMJE-TSJ disclosure forms., (Copyright © 2023 Elsevier Inc. All rights reserved.)

Study Design: This is a multicenter, prospective cohort study., Objective: This study tests the hypothesis that the elimination of lower limb compensation in patients with adult spinal deformity (ASD) will significantly increase the magnitude of sagittal malalignment., Summary of Background Data: ASD affects a significant proportion of the elderly population, impairing functional sagittal alignment and inhibiting the overall quality of life. To counteract these effects, patients with ASD use their spine, pelvis, and lower limbs to create a compensatory posture that allows for standing and mobility. However, the degree to which each of the hips, knees, and ankles contributes to these compensatory mechanisms has yet to be determined., Methods: Patients undergoing corrective surgery for ASD were included if they met at least one of the following criteria: complex surgical procedure, geriatric deformity surgery, or severe radiographic deformity. Preoperative full-body x-rays were evaluated, and age and pelvic incidence -adjusted normative values were used to model spine alignment based upon three positions: compensated (all lower extremity compensatory mechanisms maintained), partially compensated (removal of ankle dorsiflexion and knee flexion, with maintained hip extension), and uncompensated (ankle, knee, and hip compensation set to the age and pelvic incidence norms)., Results: A total of 288 patients were included (mean age 60 yr, 70.5% females). As the model transitioned from the compensated to uncompensated position, the initial posterior translation of the pelvis decreased significantly to an anterior translation versus the ankle (P.Shift: 30 to -7.6 mm). This was associated with a decrease in pelvic retroversion (pelvic tilt: 24.1-16.1), hip extension (SFA: 203-200), knee flexion (knee angle: 5.5-0.4), and ankle dorsiflexion (ankle angle: 5.3-3.7). As a result, the anterior malalignment of the trunk significantly increased: sagittal vertical axis (65-120 mm) and G-SVA (C7-ankle from 36 to 127 mm)., Conclusions: Removal of lower limbs compensation revealed an unsustainable truncal malalignment with two-fold greater SVA., Competing Interests: The authors report no conflicts of interest., (Copyright © 2023 Wolters Kluwer Health, Inc. All rights reserved.)

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.

Objective: Multiple rods are utilized in adult spinal deformity (ASD) surgery to increase construct stiffness. However, the impact of multiple rods on proximal junctional kyphosis (PJK) is not well established. This study aimed to investigate the impact of multiple rods on PJK incidence in ASD patients., Methods: ASD patients from a prospective multicenter database with a minimum follow-up of 1 year were retrospectively reviewed. Clinical and radiographic data were collected preoperatively, at 6 weeks postoperatively, at 6 months postoperatively, at 1 year postoperatively, and at every subsequent year postoperatively. PJK was defined as a kyphotic increase of > 10° in the Cobb angle from the upper instrumented vertebra (UIV) to UIV+2 as compared with preoperative values. Demographic data, radiographic parameters, and PJK incidence were compared between the multirod and dual-rod patient cohorts. PJK-free survival analysis was performed using Cox regression to control for demographic characteristics, comorbidities, level of fusion, and radiographic parameters., Results: Overall, 307/1300 (23.62%) cases utilized multiple rods. Cases with multiple rods were more likely to be revisions (68.4% vs 46.5%, p < 0.001), to be posterior only (80.7% vs 61.5%, p < 0.001), involve more levels of fusion (mean 11.73 vs 10.60, p < 0.001), and include 3-column osteotomy (42.9% vs 17.1%, p < 0.001). Patients with multiple rods also had greater preoperative pelvic retroversion (mean pelvic tilt 27.95° vs 23.58°, p < 0.001), greater thoracolumbar junction kyphosis (-15.9° vs -11.9°, p = 0.001), and more severe sagittal malalignment (C7-S1 sagittal vertical axis 99.76 mm vs 62.23 mm, p < 0.001), all of which corrected postoperatively. Patients with multiple rods had similar incidence rates of PJK (58.6% vs 58.1%) and revision surgery (13.0% vs 17.7%). The PJK-free survival analysis demonstrated equivalent PJK-free survival durations among the patients with multiple rods (HR 0.889, 95% CI 0.745-1.062, p = 0.195) after controlling for demographic and radiographic parameters. Further stratification based on implant metal type demonstrated noninferior PJK incidence rates with multiple rods in the titanium (57.1% vs 54.6%, p = 0.858), cobalt chrome (60.5% vs 58.7%, p = 0.646), and stainless steel (20% vs 63.7%, p = 0.008) cohorts., Conclusions: Multirod constructs for ASD are most frequently utilized in revision, long-level reconstructions with 3-column osteotomy. The use of multiple rods in ASD surgery does not result in an increased incidence of PJK and is not affected by rod metal type.

Objective: The objective of this study was to calibrate an updated predictive model incorporating novel clinical, radiographic, and prophylactic measures to assess the risk of proximal junctional kyphosis (PJK) and failure (PJF)., Methods: Operative patients with adult spinal deformity (ASD) and baseline and 2-year postoperative data were included. PJK was defined as ≥ 10° in sagittal Cobb angle between the inferior uppermost instrumented vertebra (UIV) endplate and superior endplate of the UIV + 2 vertebrae. PJF was radiographically defined as a proximal junctional sagittal Cobb angle ≥ 15° with the presence of structural failure and/or mechanical instability, or PJK with reoperation. Backstep conditional binary supervised learning models assessed baseline demographic, clinical, and surgical information to predict the occurrence of PJK and PJF. Internal cross validation of the model was performed via a 70%/30% cohort split. Conditional inference tree analysis determined thresholds at an alpha level of 0.05., Results: Seven hundred seventy-nine patients with ASD (mean 59.87 ± 14.24 years, 78% female, mean BMI 27.78 ± 6.02 kg/m2, mean Charlson Comorbidity Index 1.74 ± 1.71) were included. PJK developed in 50.2% of patients, and 10.5% developed PJF by their last recorded visit. The six most significant demographic, radiographic, surgical, and postoperative predictors of PJK/PJF were baseline age ≥ 74 years, baseline sagittal age-adjusted score (SAAS) T1 pelvic angle modifier > 1, baseline SAAS pelvic tilt modifier > 0, levels fused > 10, nonuse of prophylaxis measures, and 6-week SAAS pelvic incidence minus lumbar lordosis modifier > 1 (all p < 0.015). Overall, the model was deemed significant (p < 0.001), and internally validated receiver operating characteristic analysis returned an area under the curve of 0.923, indicating robust model fit., Conclusions: PJK and PJF remain critical concerns in ASD surgery, and efforts to reduce the occurrence of PJK and PJF have resulted in the development of novel prophylactic techniques and enhanced clinical and radiographic selection criteria. This study demonstrates a validated model incorporating such techniques that may allow for the prediction of clinically significant PJK and PJF, and thus assist in optimizing patient selection, enhancing intraoperative decision making, and reducing postoperative complications in ASD surgery.

Study Design: Retrospective cohort study., Objective: To compare the outcomes of patients with adult spinal deformity (ASD) following spinal fusion with the lowest instrumented vertebra (LIV) at L4/L5 versus S1/ilium., Methods: A multicenter ASD database was evaluated. Patients were categorized into 2 groups based on LIV levels-groups L (fusion to L4/L5) and S (fusion to S1/ilium). Both groups were propensity matched by age and preoperative radiographic alignments. Patient demographics, operative details, radiographic parameters, revision rates, and health-related quality of life (HRQOL) scores were compared., Results: Overall, 349 patients had complete data, with a mean follow-up of 46 months. Patients in group S (n = 311) were older and had larger sagittal and coronal plane deformities than those in group L (n = 38). After matching, 28 patients were allocated to each group with similar demographic, radiographic, and clinical parameters. Sagittal alignment restoration at postoperative week 6 was significantly better in group S than in group L, but it was similar in both groups at the 2-year follow-up. Fusion to S1/ilium involved a longer operating time, higher PJK rates, and greater PJK angles than that to L4/L5. There were no significant differences in the complication and revision rates between the groups. Both groups showed significant improvements in HRQOL scores., Conclusions: Fusion to S1/ilium had better sagittal alignment restoration at postoperative week 6 and involved higher PJK rates and greater PJK angles than that to L4/L5. The clinical outcomes and rates of revision surgery and complications were similar between the groups.

Background: To investigate the variation in total episode-of-care (EOC) payment and quality-adjusted life-year (QALY) gain for complex adult spine deformity surgeries in the United States, adjusting for case type and surgeon preferences., Methods: Patients aged >18 years with adult spine deformity with Medicare Severity-Diagnosis-Related Groups (DRGs) 453-460 and a minimum of 2 years of follow-up from index surgery were included. Index and total payments were calculated using Medicare's Inpatient Prospective Payment System. All costs were adjusted for inflation to 2020 U.S. dollar values. QALYs gained were calculated using baseline, 1-year, and 2-year Short-Form 6D scores. Mixed-effect models were used to estimate the proportion of variation in total EOC payment and QALY gain., Results: A total of 330/543 patients from 6 sites were included. Mean age was 62.4 ± 11.9 years, 79% were women, and 92% were white. The mean index and total EOC payment were $77,302 and $93,182, respectively. Patients gained on average 0.15 QALY (P < 0.0001) 2 years after surgery. In unadjusted analysis, 39% of the variation in total EOC payment across the 6 centers was attributable to relative weight of DRG and base rate. Adjusting for patient and procedural factors increased the proportion of variation in total EOC payments across the centers to 56%. Less than 2% of the variation in QALY gain was observed across the 6 centers., Conclusions: Medicare-based payments for complex spine deformity fusions are primarily driven by relative weight of the DRG and the hospital's base rate. Patient and procedural factors are unaccounted for in the DRG-based payments made to the providers., (Copyright © 2022 Elsevier Inc. All rights reserved.)

Objective: The objective of this study was to use an unsupervised cluster approach to identify patterns of operative adult spinal deformity (ASD) and compare the perioperative outcomes of these groups., Methods: A multicenter data set included patients with complex surgical ASD, including those with severe deformities, significant surgical complexity, or advanced age who underwent a multilevel fusion. An unsupervised cluster analysis allowing for 10% outliers was used to identify different deformity patterns. The perioperative outcomes of these clusters were then compared using ANOVA, Kruskal-Wallis, and chi-square tests, with p values < 0.05 considered significant., Results: Two hundred eighty-six patients were classified into four clusters of deformity patterns: hyper-thoracic kyphosis (hyper-TK), severe coronal, severe sagittal, and moderate sagittal. Hyper-TK patients had the lowest disability (mean Oswestry Disability Index [ODI] 32.9 ± 17.1) and pain scores (median numeric rating scale [NRS] back score 6, leg score 1). The severe coronal cluster had moderate functional impairment (mean physical component score 34.4 ± 12.3) and pain (median NRS back score 7, leg score 4) scores. The severe sagittal cluster had the highest levels of disability (mean ODI 49.3 ± 15.6) and low appearance scores (mean 2.3 ± 0.7). The moderate cluster (mean 68.8 ± 7.8 years) had the highest pain interference subscores on the Patient-Reported Outcomes Measurement Information System (mean 65.2 ± 5.8). Overall 30-day adverse events were equivalent among the four groups. Fusion to the pelvis was most common in the moderate sagittal (89.4%) and severe sagittal (97.5%) clusters. The severe coronal cluster had more osteotomies per case (median 11, IQR 6.5-14) and a higher rate of 30-day implant-related complications (5.5%). The severe sagittal and hyper-TK clusters had more three-column osteotomies (43% and 32.3%, respectively). Hyper-TK patients had shorter hospital stays., Conclusions: This cohort of patients with complex ASD surgeries contained four natural clusters of deformity, each with distinct perioperative outcomes.