BACKGROUND CONTEXT:Increasing number of patients are undergoing surgical treatment for adult spinal deformity (ASD). The main indications are pain, disability and loss of function. Multiple patient- reported health related quality of life (HRQOL) measures are utilized to assess functional status and disability before and after the surgery. Some components of these questionnaires may be more pertinent in the elderly population. PURPOSE:Primary aim was to assess key functional outcomes were most relevant to elderly patients undergoing multilevel fusion surgery for ASD. Secondary aim was to assess if these functional improvements were maintained over the follow up period. STUDY DESIGN/SETTING:Post hoc analysis of prospectively collected data from multicenter observational study, where primary outcome was the absolute changes in the SRS-22r total and subtotal scores between baseline and 2-years FU. PATIENT SAMPLE:A total of 219 patients. OUTCOME MEASURES:Self-reported and functional measures were included. Function was assessed using the Scoliosis Research Society 22r (SRS-22r) function domain, and the personal care, walking, sitting and standing sections from the Oswestry disability index (ODI) and EuroQol- 5 Dimension (EQ-5D-3L scores). METHODS:Patients ≥60 years of age from 12 international centres undergoing spinal fusion of at least 5 levels were included. Follow up visits were performed at 10 weeks, 12 months, 24 months and 60 months. RESULTS:A total of 219 patients (80.4% females) were included with a mean age of 67.5 years. The mean SRS-22r function scores preoperative were 2.70 (CI: 2.60-2.80), which improved to 3.46 (CI: 3.36-3.56) by 2 years postsurgery and were maintained at 5 years (3.39, CI: 3.27-3.51). 44.9% patients were either bedbound or had primarily no activity before the surgery which reduced to 18.3 % at 2 years and 17.4% at 5 years follow up. Similarly, the percentage of patients that could stand >30 minutes improved from 24.5% to 68.6% at 2 years and 59.4% at 5 years. 26% of the patients could walk for a mile or more before surgery which improved to 63.1 % at 2 years and maintained in 58.7% patients at 5 years. 43.1 % had unlimited sitting preoperatively, that improved to 65.3% at 2 years and 64.7% at 5 years. Normal social life was seen in 19.2% of patients at baseline compared to 57.5% at 2 years and 52.7% at 5 years. CONCLUSIONS:Elderly patients undergoing multilevel spinal fusions for ASD experienced significant functional improvements, which were maintained at 5 years postoperatively. This practical information can be utilized during patient counselling preoperatively when considering functional outcomes after major ASD surgery in patients over 60 years of age.

BACKGROUND CONTEXT Decisional regret (DR) reflects an individual’s perception of an outcome relative to expectations. The evolution of patient and surgeon DR after adult spinal deformity (ASD) surgery and factors contributing to potential asymmetry remain unclear. PURPOSE To assess whether patients and surgeons perceive outcomes and revisions after ASD surgery differently within a decisional regret framework. STUDY DESIGN/SETTING Retrospective analysis of a multicenter prospective ASD database. PATIENT SAMPLE A total of 234 patients with complete decisional regret data at 6 weeks, 1 year, and 2 years. OUTCOME MEASURES Decisional regret measured on a 5-point Likert scale. METHODS Patients (n=1,388) undergoing ASD surgery were surveyed at 6 weeks, 1 year, and 2 years postoperatively regarding whether they would choose to undergo the same surgery again (patient DR). Surgeons were asked the analogous question (surgeon DR). Responses were scored on a Likert scale (5=definitely yes to 1=definitely no). Patient–surgeon disagreement was defined as D=patient DR minus surgeon DR, with distributional symmetry assessed using the Wilcoxon signed-rank test. Multivariable ordinal regression evaluated factors associated with DR and disagreement at 2 years, including age, ODI, radiographic alignment, number of levels fused, psychiatric comorbidities, and revision status. Fisher’s exact test evaluated the effect of revision on subsequent DR. RESULTS At 6 weeks, DR was low among both patients (87% would make the same choice) and surgeons (95%). Among patients with complete 2-year follow-up (n=234), DR remained stable or improved over time (patient/surgeon: 56.8%/67.0% unchanged; 18.4%/9.4% improving; p<0.001). Patient–surgeon disagreement was minimal (mean |D|<0.5 at all time points), with slightly higher patient DR at 6 weeks (D=−0.26, p<0.001) and 1 year (D=−0.19, p<0.002), but no difference at 2 years (D=−0.01, p=0.73). Lower patient DR relative to surgeons was associated with older age (β=0.015, p=0.006), psychiatric comorbidities (β=0.28, p=0.04), and improved sagittal vertical axis (β=−0.45 cm, p=0.006). At 2 years, revision surgery was associated with increased patient DR (p=0.03), while older age was associated with increased surgeon DR (p=0.001). Following revision, patients were more likely to report decreased regret (39.7% vs 18.5%, p<0.001), whereas surgeon DR did not significantly change (p=0.13). CONCLUSIONS Both patients and surgeons report low decisional regret following ASD surgery, with minimal asymmetry that resolves by 2 years postoperatively. Following revision surgery, patients tend to experience reduced regret, whereas surgeon regret remains unchanged. These findings have important implications for patient counseling and expectation management. FDA Device/Drug Status This abstract does not discuss or include any applicable devices or drugs.

OBJECTIVE:The aim of this study was to determine predictors of the minimum clinically important difference (MCID) in the Neck Disability Index (NDI) following cervical spinal deformity surgery. METHODS:A retrospective review was performed of a prospective, multicenter adult cervical spinal deformity database. All patients had baseline and 1-year NDI scores. Patients met MCID with an improvement of NDI by 7 points between baseline and 1 year, as previously established. Baseline demographics, comorbidities, and both baseline and 1-year spinopelvic parameters were evaluated for statistical significance in a univariate logistic regression analysis. Significant variables, in addition to baseline NDI, were analyzed in a multivariable logistic regression model by backward selection with Akaike information criterion minimization. RESULTS:A total of 122 patients were included with a median age of 62 (IQR 56, 69) years; 62% of patients were female. Of the 122 patients, 72 (59%) achieved NDI MCID at 1 year. Predictors of achieving MCID on univariate analysis included a lower Charlson Comorbidity Index (CCI) total score (OR 0.70, p = 0.03), depression as a comorbidity (OR 2.9, p = 0.02), lower C2 tilt at the 1-year follow-up (OR 0.92, p = 0.02), and a greater difference between 1-year postoperative C2-7 sagittal vertical axis (SVA) and preoperative C2-7 SVA (OR 0.98, p = 0.0495). On multivariable logistic regression analysis, predictors of achieving MCID included a lower CCI (OR 0.62, p = 0.03), depression as a comorbidity (OR 3.1, p = 0.059), a greater change in C2-7 SVA at the 1-year follow-up compared with baseline (OR 0.97, p = 0.055), and baseline NDI (OR 1.02, p = 0.24) with an area under the curve of 0.74. CONCLUSIONS:The best-fit multivariable model included higher baseline NDI, a greater change in C2-7 SVA, patient-reported baseline depression, and lower CCI as important factors in predicting NDI MCID.

Adult spinal deformity patients undergoing total hip arthroplasty experience higher hip dislocation rates than those with normal spinal alignment. The traditional Lewinnek safe zone does not account for spinopelvic variation such as pelvic retroversion. To address this, three patient-specific normative zones for acetabular anteversion were defined. A multicenter retrospective analysis of 146 adult spinal deformity patients and 47 asymptomatic controls was performed using three-dimensional biplanar radiograph reconstructions to measure spinopelvic alignment and acetabular orientation. Normative Zone 1, for patients not undergoing spinal realignment, was delineated by the 95% confidence interval limits: minimum anteversion = 0.3182 × pelvic tilt +2.947 and maximum anteversion = 0.3317 × pelvic tilt +25.823. Normative Zone 2, for patients following spinal realignment, was based on pelvic incidence: minimum anteversion = 0.0682 × pelvic incidence +9.7749 and maximum anteversion = 0.0698 × pelvic incidence +21.5218. Normative Zone 3, intended for cases with uncertain spinal correction plans, was defined as the intersection of Zones 1 and 2, yielding a narrower target anteversion range. These zones enable patient-specific cup placement that accounts for existing or planned spinal alignment, with the potential to reduce dislocation risk. Clinical Significance: This study provides acetabular cup orientation tailored to each patient's spinopelvic alignment and surgical plan, potentially reducing dislocation rates in spinal malalignment patients.

BACKGROUND CONTEXT The long-term outcomes of non-revised rod fracture (RF) after long-segment adult spinal deformity (ASD) fusion remain poorly defined. The clinical significance of RF over extended follow-up is not well understood. PURPOSE To determine which rod fractures can be safely managed nonoperatively and to identify predictors of progression following long thoracic-to-sacrum/pelvis fusion with a minimum 10-year follow-up. STUDY DESIGN/SETTING Single-center retrospective cohort study. PATIENT SAMPLE A total of 165 patients undergoing long thoracic-to-sacrum/pelvis fusion between 2004 and 2014 with a minimum 10-year follow-up (mean 148.6 months, range 120–255). Mean age was 54.5 years, and 90.9% were female. OUTCOME MEASURES Rod fracture progression (new fractures or displacement during observation), revision surgery rate, and time to progression. METHODS Rod fractures were classified at diagnosis by laterality (unilateral vs bilateral) and displacement (displaced vs non-displaced) and managed either with observation or revision. Progression was defined as new fractures or displacement during observation. Time-to-event analyses were used to identify predictors of progression and confirm adequacy of follow-up duration. RESULTS Rod fracture occurred in 67 of 165 patients (40.6%). At diagnosis, 19 patients (28.4%) underwent immediate revision, while 48 patients (71.6%) were initially managed nonoperatively. During observation, 15 of 45 patients (33.3%) demonstrated radiographic progression, and 7 of 48 patients (14.6%) ultimately required revision at a mean of 39.2 months after initial RF diagnosis. Mean time from RF diagnosis to progression was 56.3 months (median 60.5 months). Rod fracture timing was the strongest predictor of progression, with progression occurring earlier in patients with RF (47.8 vs 86.6 months; p=0.002). Mean and median time from RF diagnosis to progression (56.3 and 60.5 months, respectively) did not differ from observation time in nonprogressed patients (65.0 and 67.8 months; p=0.48), supporting adequate follow-up duration. Higher postoperative thoracic kyphosis was also associated with progression (p=0.020). CONCLUSIONS Early and late rod fractures demonstrate distinct clinical behavior, with earlier RF associated with higher risk of progression. Most rod fractures, particularly unilateral non-displaced fractures, can be safely managed nonoperatively, with approximately 89% avoiding revision over long-term follow-up. Rod fracture timing is a key factor for risk stratification and postoperative surveillance. FDA Device/Drug Status This abstract does not discuss or include any applicable devices or drugs.

INTRODUCTION:Bone health is critical to spine surgery. Studies have demonstrated the role and benefit of optimizing bone health before spinal surgery. However, bone health screening and treatment patterns vary considerably among spine surgeons. The purpose of this study was to assess the global screening, prevention, and treatment of osteoporosis and bone health in spine surgery. METHODS:A 34-item questionnaire was created and distributed anonymously, globally to AO Spine subscribers. The word responses were analyzed manually and categorized. Each participant was assigned a region: Asia, Africa, Central America, Europe, North America, or South America. Quantitative outcomes include the frequency and proportion of respondents who selected each answer. Qualitative outcomes include written responses to select prompts. Chi-squared tests was performed to compare proportions based on categories. RESULTS:The response rate was 3.4%; 36.2% of respondents were from Asia, 28.7% Europe, 12.8% South America, 9.8% North America, 9.6% Africa, and 2.9% Central America. 69.8% finished residency in orthopaedic surgery, 24.5% in neurosurgery, and 5.7% in others; 58.6% completed a spine fellowship. Before instrumented fusion, 61.1% routinely checked dual-energy radiograph absorptiometry (DXA). If osteoporosis is detected on DXA before an instrumented fusion, 65.1% would alter their treatment plan; 64.7% refer the patient to treatment first. The rate of DXA screening before instrumented fusion differed based on the region ( P < 0.001): the highest was in North America at 89.5%, and the lowest was in Africa at 36.6%. Before instrumented fusion, fellowship-trained surgeons screened DXA more routinely than those without a fellowship, at 67.9% and 52.5%, respectively ( P = 0.002). CONCLUSIONS:Globally, bone health screening before spine surgery has increased. However, large regional variations in practice patterns exist regarding the screening of bone health pre- and perioperatively.

This study is focused entirely on the changes in self-image scores which occur when spinal deformity surgery is performed for primary (AdIS) and revision (rAdIS) patients with adult idiopathic scoliosis, by an all-posterior approach. Single-surgeon, single-center retrospective review of a consecutive series of adult idiopathic scoliosis (AdIS) patients treated with posterior spinal fusion (PSF) from 2015 to 2022. Patient-reported SRS-22 Self-Image, radiographic, and perioperative outcomes were recorded preoperatively and at 2-year follow-up. Patients undergoing primary surgery (AdIS) were compared to revision surgery (rAdIS) patients. 123 patients were included, 75 primary (AdIS) and 48 revision (rAdIS) patients. Primary AdIS patients had larger preoperative major coronal curve magnitude (63° vs. 49°, p < 0.0001), though smaller curves at 2 years (21° vs. 31°, p = 0.0002). Primary patients had less preoperative PI-LL mismatch (14° vs. 30°, p < 0.0001), though similar postoperative mismatch (17° vs. 15°, p = 0.4339). AdIS had negative sagittal alignment preoperative compared to positive alignment in rAdIS patients (CrSVA-H -15 mm vs. 12 mm, p < 0.0001), though similar sagittal alignment postoperative (CrSVA-H -9 mm vs. -17 mm, p = 0.4035). Both groups had similar EBL (1400 mL vs. 1600 mL, p = 0.1011), OR times (8 h vs. 8.4 h, p = 0.3160) and levels fused (16.4 vs. 15.2, p = 0.1249). AdIS had fewer three-column osteotomies (7

BACKGROUND CONTEXT Rod fracture (RF) is a common late mechanical complication following adult spinal deformity (ASD) surgery, particularly after long-segment fusion. While early outcomes have improved, the long-term temporal behavior of RF remains poorly understood. PURPOSE To characterize the long-term survival pattern of rod fracture following long thoracic-to-sacrum/pelvis fusion using time-to-event analysis and to identify independent risk factors. STUDY DESIGN/SETTING Single-center retrospective cohort study. PATIENT SAMPLE A total of 165 ASD patients undergoing long thoracic-to-sacrum/pelvis fusion between 2004 and 2014 with a minimum 10-year follow-up (mean 148.6 months, range 120–255). Mean age was 54.5 years, and 90.9% were female. Accessory rods were used in 23 patients (13.9%), and all three-column osteotomies were pedicle subtraction osteotomies (20 patients, 12.1%). OUTCOME MEASURES Rod fracture occurrence, time to rod fracture, and revision surgery rate. METHODS Rod fracture was analyzed as a time-dependent event using Kaplan–Meier survival analysis. Group comparisons were performed using Student’s t-tests and Fisher’s exact tests. Variables significant on univariate analysis were entered into multivariate Cox proportional hazards regression, with statistical significance set at p<0.05. RESULTS Among 165 patients, rod fracture occurred in 67 (40.6%) at a median time of 60.7 months (interquartile range 38–95), with no plateau observed on Kaplan–Meier analysis. Of these, 26 patients (38.8%) underwent revision surgery, and 4 experienced recurrent fracture requiring a second revision. Baseline demographics, surgical characteristics, and alignment parameters were similar between groups. On univariate analysis, rod fracture was associated with smaller sagittal corrections (PI–LL, lumbar lordosis, pelvic tilt, sacral slope), greater coronal correction, use of cobalt-chrome (CoCr) rods, smaller rod diameter (<6.35 mm), and shorter operative time. On multivariate analysis, only CoCr rod material remained independently associated with rod fracture (HR 3.07; 95% CI 1.88–5.04; p<0.001). CONCLUSIONS Rod fracture demonstrates a progressive accumulation over time, reaching 40.6% at a median of approximately 5 years without plateau. While multiple factors were associated with rod fracture on univariate analysis, only CoCr rod material remained an independent predictor. Revision for rod fracture occurred in 15.7% of the overall cohort. These findings highlight the importance of implant selection and long-term surveillance in patients undergoing long-segment ASD fusion. FDA Device/Drug Status This abstract does not discuss or include any applicable devices or drugs.

BACKGROUND CONTEXT The influence of upper instrumented vertebra (UIV) selection on proximal junctional kyphosis (PJK) in adult spinal deformity surgery remains incompletely defined, particularly over long-term follow-up. Short-term studies may underestimate UIV-related risk. PURPOSE To evaluate whether UIV level affects the incidence and timing of PJK at a minimum of 10-year follow-up after thoracic-to-sacropelvic fusion for adult spinal deformity. STUDY DESIGN/SETTING Single-center retrospective cohort study. PATIENT SAMPLE A total of 165 adult spinal deformity patients undergoing thoracic-to-sacropelvic fusion with a minimum 10-year follow-up (mean 12.4 ± 2.7 years), including 97 upper thoracic (UT, T1–T6) and 68 lower thoracic (LT, T7–T12) UIV levels. OUTCOME MEASURES Proximal junctional kyphosis (PJK; proximal junctional angle ≥20°), proximal junctional failure (PJF), reoperation, and rod fracture. METHODS Patients were stratified into UT and LT groups based on UIV level. Cumulative PJK prevalence was assessed at 2, 5, and 10 years postoperatively. Multivariate logistic regression models adjusted for age, sex, body mass index, and revision status. RESULTS A total of 165 patients were included. Groups differed in diagnosis and sex distribution but had similar rates of pelvic fixation. Overall PJK prevalence was 29.7%. At 2 years, PJK rates did not differ significantly between groups (UT 8.5% vs LT 13.0%; adjusted OR 2.21; p=0.25). By 5 years, LT UIV was associated with higher PJK rates (11.1% vs 27.8%; adjusted OR 3.35; 95% CI 1.22–9.21; p=0.019), which persisted at 10 years (17.9% vs 39.0%; adjusted OR 2.93; 95% CI 1.26–6.84; p=0.013). PJK developing beyond 10 years was not associated with UIV level (UT n=6, LT n=4). UIV selection did not significantly influence rates of PJF, rod fracture, or reoperation. CONCLUSIONS Lower thoracic UIV selection is independently associated with a delayed but significantly increased risk of proximal junctional kyphosis, becoming evident after 2 years and persisting through 10 years. Late-onset PJK beyond 10 years appears independent of UIV selection. Studies limited to short-term follow-up may underestimate the impact of UIV selection on long-term PJK risk. FDA Device/Drug Status This abstract does not discuss or include any applicable devices or drugs.

BACKGROUND CONTEXT Although adolescent idiopathic scoliosis (AIS) may be diagnosed during adolescence, circumstances may delay operative intervention until a later time, including into adulthood. The impact of delayed surgical intervention on postoperative outcomes remains unclear. PURPOSE This study evaluated postoperative outcomes following operative correction of idiopathic scoliosis, comparing adolescent surgery (ages 10–18) with surgery performed at age 19 years or older. STUDY DESIGN/SETTING Retrospective cohort study. PATIENT SAMPLE Patients undergoing operative correction of idiopathic scoliosis between 2015 and 2025 were identified from the TriNetX Research Network. Cohorts were defined by age at index surgery: adolescent idiopathic scoliosis (AIS) surgery (10–18 years) and delayed surgery in young adult idiopathic scoliosis (yAdIS) (19–40 years). OUTCOME MEASURES The primary outcome was pseudarthrosis within two years of surgery. Secondary outcomes included fracture, hardware-related complications, venous thromboembolism, and surgical site infection. METHODS Using the TriNetX Research Network, patients undergoing operative correction of idiopathic scoliosis between 2015 and 2025 were identified. Cohorts were defined by age at index surgery: AIS surgery (10–18 years) and delayed surgery in yAdIS (19–40 years). Propensity score matching (1:1) was performed based on Charlson Comorbidity Index, body mass index (BMI), and relevant surgical factors. RESULTS After 1:1 propensity score matching of BMI and comorbidities, 613 patients remained in each cohort, with 73% female patients in both groups. Mean age was 14.7 ± 2.2 years in the AIS cohort and 23.2 ± 5.5 years in the yAdIS cohort. The incidence of pseudarthrosis within two years was significantly higher among yAdIS patients compared with AIS patients (7.11% vs 2.42%; risk ratio [RR] = 2.93; 95% CI [1.65, 5.22]; p < 0.001). Hardware-related complications within two years were also more common in the yAdIS cohort compared with the AIS cohort (4.69% vs 2.10%; RR = 2.23; 95% CI [1.17, 4.25]; p = 0.012). Postoperative medical complications, including fracture, venous thromboembolism, and surgical site infection, were evaluated but occurred in fewer than 10 events. CONCLUSIONS Among patients with idiopathic scoliosis, operative correction performed in young adulthood was associated with higher rates of pseudarthrosis and hardware-related complications compared with adolescent surgery, highlighting potential differences in fusion durability by age at intervention. FDA Device/Drug Status This abstract does not discuss or include any applicable devices or drugs.

Epigenetic changes, such as DNA methylation (DNAm), offer a measure of biological age distinct from chronological age. DNAm PhenoAge is one such biomarker that is more strongly related to morbidity, mortality, and physical function than chronological age. More accurate risk stratification methods are needed for ASD surgeries, where complications remain difficult to predict with an increasingly aged population. A multicenter ASD registry was queried. DNAm PhenoAge was calculated as per Levine et al. (6). Multivariable logistic regression examined the associations of DNAm PhenoAge and chronological age with perioperative adverse events (AE). The relative improvements in model discrimination, fit, and classification performance were compared. Adjusted odds ratios compared the risk of 55 versus 75 years for each age metric. Laboratory data were available for 200 patients. Mean DNAm PhenoAge was lower than chronological (DNAm PhenoAge, 53.7 ± 18.1; chronological, 61.1 ± 15.4; p < 0.001; 95

STUDY DESIGN:Prospective multicenter study. OBJECTIVE:To determine the incidence of all-cause mortality after adult spinal deformity surgery. SUMMARY OF BACKGROUND DATA:Patients undergoing adult spinal deformity surgery are often frail and the procedures are invasive. The incidence of all-cause mortality among patients undergoing cervical or thoracolumbar deformity surgery is unclear. MATERIALS AND METHODS:Using two prospective, multicenter databases, we identified patients who underwent surgery for cervical deformity surgery from 2013 to 2020 (n=169) or thoracolumbar deformity from 2008 to 2020 (n=1507). Mortality incidence density was calculated as follows: 100×(number of deaths)/(sum of total years of follow-up for all patients). RESULTS:Of 169 participants in the cervical group (mean±SD age, 61±10 yr), death occurred in 19 (11%). The mean time to death was 25±19 months. Mortality incidence density was 4.4 deaths per 100 person-years. The 30-day mortality rate was 0.6% (1/169) and the 90-day mortality rate was 1.2% (2/169). The three most common causes of death were arrhythmia/cardiac arrest (16%), congestive heart failure (11%), and pneumonia (11%). There were no intraoperative deaths. Of 1507 participants in the thoracolumbar group (mean±SD age, 61±14 yr), death occurred in 53 (3.5%). The mean time to death was 32.5±21.5 months. Mean duration of follow-up was 1.8±1.5 years. The mortality incidence density was 0.8 deaths per 100 person-years. The 30-day mortality rate was 0.1% (1/1507) and 90-day mortality rate was 0.3% (4/1507). The three most common causes of death were nonspine malignancy (13%), pneumonia (9%), and arrhythmia/cardiac arrest (6%). CONCLUSIONS:The number of deaths per year was higher among cervical deformity patients (4.4 per 100 person-years) than among thoracolumbar deformity patients (0.8 per 100 person-years). Pneumonia and arrhythmia/cardiac arrest were among the most common causes of death in both groups. LEVEL OF EVIDENCE:Level III.

BACKGROUND:Kinematic alignment in total knee arthroplasty has been increasingly investigated for its potential improved functional outcomes. The coronal plane alignment of the knee (CPAK) classification was developed to better define native coronal alignment (to act as a target) using joint line obliquity (joint line apex [distal, neutral, or proximal]) and the arithmetic hip-knee-ankle angle (varus, neutral, or valgus). Since the literature is limited in addressing how spinal deformity influences CPAKs, this study examined the distribution of CPAK types in patients who had adult spinal deformity and evaluated whether surgical correction of the spinal deformity alters this distribution. METHODS:A total of 264 patients (528 knees) from a prospectively maintained multicenter database were included based on the availability of full-body biplanar radiographs both before spinal realignment surgery and at 1-year follow-up. The CPAK classification was assigned at each time point and compared to the distribution reported in a healthy population. Statistical analyses included Chi-square goodness-of-fit testing, univariate correlation analyses, and multivariate regressions. RESULTS:Preoperative and postoperative CPAK distributions differed significantly from the healthy population (P < 0.001), but the overall distribution of the cohort did not change significantly following surgery. However, on an individual level, 36% of knees showed a change in CPAK classification. These patients were older and had higher body mass indexes and greater changes in global spinal alignment, pelvic shift, and knee flexion. Multivariate analyses identified changes in lumbar lordosis, pelvic shift, and sagittal knee angle as independent predictors of change in arithmetic hip-knee-ankle angle. CONCLUSIONS:Patients who had adult spinal deformity demonstrate a distinct CPAK profile. Though global distribution remains stable following spinal realignment, substantial individual variability exists, with some patients experiencing major changes to coronal knee alignment postoperatively. Clinicians should interpret CPAK classification cautiously in this population, especially in those at risk for or undergoing spinal realignment surgery.

VPAs quantify the spatial relationship of each vertebra to the pelvis and are independent of patient positioning, making them a valuable tool for preoperative planning and intraoperative assessment of sagittal alignment. Given the biomechanical relevance of vertebral pelvic angles (VPAs), their role in predicting proximal junctional kyphosis (PJK) warrants further investigation. We hypothesized that malalignment of VPAs is associated with an increased risk of developing PJK following long-segment fusion for adult spinal deformity (ASD). ASD patients ≥ 18 years undergoing ≥ 5-level posterior spinal instrumentation and fusion (PSIF) to the pelvis from 2015 to 2022 were included. VPAs (C2PA, T1PA, T4PA, T10PA, L1PA) were measured on standardized radiographs preoperatively and immediately postoperatively. PJK was defined radiographically by two criteria: (1) a postoperative proximal junctional sagittal Cobb angle ≥ 10°, and (2) an increase of ≥ 10° compared to the preoperative angle between the UIV and UIV + 2. Associations between VPA changes, published alignment thresholds (L1PA = PI × 0.5 − 19° ± 2°; T4–L1PA mismatch = − 3° to + 1°), and PJK were assessed using ROC analysis and logistic regression. A total of 266 patients (mean age: 57.5 ± 12.5 years; 74.8

OBJECTIVE:Rates of revision surgery following operative treatment for adult symptomatic lumbar scoliosis (ASLS) are high, mostly due to mechanical complications, including proximal junctional failure (PJF) and pseudarthrosis/rod fracture (RF). How these revisions impact long-term clinical outcomes remains unclear. The aim of this study was to assess revision rates for the two most common mechanical complications (PJF and RF) and the potential impact of these revisions on patient-reported outcome measures over 8 years of follow-up for operatively treated patients with ASLS. METHODS:This retrospective review used data from a multicenter prospective ASLS study to assess operative versus nonoperative ASLS treatment. Patients were 40-80 years of age with ASLS (Cobb ≥ 30° and Oswestry Disability Index [ODI] score ≥ 20 or revised Scoliosis Research Society 22-item questionnaire [SRS-22r] score ≤ 4.0 in pain, function/activity, and/or self-image domains). Patients who underwent long-segment posterior fusion (thoracic spine to sacrum) were assessed for the impact of revision due to mechanical complications on outcomes (SRS-22r subscore and ODI score). RESULTS:Overall, 160 patients (141 female, median age 61.31 years) met inclusion criteria. Of these, 53 (33.1%) required revision (71 revisions, 25 for PJF and 46 for RF) for mechanical complications, with 1, 2, and 3 revisions in 39, 10, and 4 patients, respectively. By 8 years of follow-up, patients had a 38% estimated risk of revision for mechanical complications. The mean time to the first and second revisions was 3.0 years (SD 2.1) and 4.8 years (SD 2.3), respectively. In unadjusted analyses, patients with ≥ 1 revision had a significant negative impact on their 8-year ODI score (mean difference 9.40, 95% CI 3.68-15.13; p = 0.0013) and SRS-22r subscore (mean difference -0.27, 95% CI -0.49 to -0.05; p = 0.0141). Patients with ≥ 2 revisions experienced the greatest impact on both their ODI score (mean difference 14.48, 95% CI 4.89-24.07; p = 0.0031) and SRS-22r subscore (mean difference -0.38, 95% CI -0.74 to -0.02; p = 0.0361), with the impact exceeding the minimum detectable measurement difference for the ODI score (7) but not the SRS-22r subscore (0.4). In adjusted analyses, these differences were attenuated for patients with ≥ 2 revisions: ODI score (mean difference 14.14, 95% CI 4.52-23.75; p = 0.0040) and SRS-22r subscore (mean difference -0.30, 95% CI -0.67 to 0.06; p = 0.1001). CONCLUSIONS:By the 8-year follow-up, revision surgery for mechanical complications was required in an estimated 38% of operative ASLS patients. Patients who underwent ≥ 1 revision had a significant negative impact on ODI score and SRS-22r subscore, and this impact was greatest with ≥ 2 revisions. These findings emphasize the need for better techniques to reduce mechanical complications in ASLS surgery.

OBJECTIVE:The all-payer model is a healthcare payment system unique to the state of Maryland, while the Medicare Severity-Diagnosis-Related Group (MS-DRG) model is used by all other states. The purpose of this study was to investigate differences in reimbursement and inpatient length of stay (LOS) in adult spinal deformity (ASD) surgery between the all-payer and MS-DRG models. METHODS:MS-DRG reimbursements were calculated using the Centers for Medicare & Medicaid Services Web Pricer tool; reimbursements for the all-payer model were compiled from a single institution in the state of Maryland. Payments for the most frequently occurring ASD MS-DRGs (codes 453, 454, 455, 456, 457, 458, and 460) were analyzed for fiscal years 2018-2023. The mean inpatient LOS was calculated for each MS-DRG code and reimbursement model. RESULTS:When comparing 416 MS-DRG and 1783 all-payer model accounts, the overall mean reimbursements for ASD surgery were significantly lower under the MS-DRG model ($59,199 vs $77,246, p < 0.001). The mean reimbursement payments for MS-DRG codes 453, 454, 455, 456, 457, and 460 were significantly higher under the Maryland all-payer model (p < 0.001). The mean LOS was significantly shorter in the all-payer model for MS-DRG code 453 (p = 0.046) and longer for code 457 (p < 0.001). For all other codes, no significant differences in LOS were observed. CONCLUSIONS:ASD surgery reimbursements are higher overall under the Maryland all-payer model compared with the MS-DRG model. The mean inpatient LOS did not differ significantly across most MS-DRG codes, highlighting the financial viability of an all-payer model in a healthcare system.

Aims Proximal junctional kyphosis (PJK) remains a major complication after surgery for adult spinal deformity (ASD). While postoperative alignment is a recognized modifiable risk factor, objective methods for selecting the upper instrumented vertebra (UIV), a key modifiable factor, are lacking. We aimed to determine whether preoperative sagittal alignment, specifically cervicothoracic alignment, predicts the risk of PJK, and whether this risk can be mitigated by UIV selection, focusing on factors available at the time of surgical planning. Methods From a multicentre, prospective ASD registry, we identified patients who had undergone fusion to the sacrum or pelvis and had an upper (T1–T5) or lower thoracic (T9–L1) UIV, with a two-year or more radiological follow-up, excluding those with a previous fusion over more than four levels. The primary outcome was PJK within two years. Multivariable logistic regression modelled the risk of PJK by UIV region, preoperative C2–T9 pelvic angle (PA), age, sex, and pelvic incidence, testing for interaction between UIV region and C2–T9 PA. Adjusted absolute risk reduction (ARR) and number needed to be exposed (NNEB) were calculated. Multivariable linear regression estimated two-year patient-reported outcome measures, adjusting for baseline scores, age, UIV, and PJK. Results A total of 627 patients across 20 centres were included (median age 66 years (IQR 59 to 70); 483 (77%) female). The UIV was lower thoracic in 380 (61%) and upper thoracic in 247 (39%) patients. PJK occurred in 149 (39%) lower thoracic and 38 (15%) upper thoracic UIV patients. There was a significant interaction (p = 0.028) between preoperative C2–T9 PA and UIV region. At a preoperative C2–T9 PA of 14° (cohort median), an upper thoracic UIV had an adjusted ARR of 36% and NNEB was 2.8. Females had an adjusted odds ratio of 1.62 (95% CI 1.03 to 2.59; p = 0.042) for PJK. Conclusion Worse preoperative sagittal malalignment, measured by C2–T9 PA, was associated with a higher risk of PJK and depended on UIV region. An upper thoracic UIV in patients with high preoperative C2–T9 PA may reduce PJK. Cite this article: Bone Joint J 2026;108-B(7):943–951.

BACKGROUND CONTEXT Despite advances in surgical techniques and the development of novel sagittal alignment targets, temporal trends of surgically achieved alignment goals have not been examined. PURPOSE Evaluate the evolution of achieved alignment following ASD surgeries. STUDY DESIGN/SETTING Retrospective multicenter registry of ASD surgeries (2008–2025). PATIENT SAMPLE A total of 1,166 ASD patients. OUTCOME MEASURES Sagittal alignment at 6 weeks and 2 years, SRS22 Satisfaction, and 2-year revision rates. METHODS Patients from two large multicenter ASD registries were reviewed and included if met the following criteria: preoperative SRS-Schwab type N or L treated with posterior fusion from thoracic (T1-12) to ilium. Patients were stratified into 3 surgical epochs: Epoch 1 (2008–2013), Epoch 2 (2014–2019), and Epoch 3 (2020–2025). Demographics and alignments were compared using ANOVA/Kruskal–Wallis with post hoc corrections. Alignment variance assessed via Levene testing (p<0.05). RESULTS A total of 1,166 patients were included (mean age 68.1 ± 8.4 and 67% females), with 182 in Epoch 1 (FU rate 82%), 472 in Epoch 2 (FU rate 67%) and 512 in Epoch 3 (FU rate 30%). Patient age increased across epochs (Epoch 1: 66±11 years; Epoch 3: 69±8 years, p<0.001) as well as lower proportion of females in Epoch 3 (61% vs 75%, p<0.001). Despite this, Epoch 3 demonstrated lower comorbidity burden (p<0.001), lower baseline ODI (p=0.003), and higher baseline SRS-22 total scores (p<0.001). Baseline spinopelvic parameters were largely comparable across epochs (no significant differences in PT, PI–LL, regional lordosis, or pelvic angles), though C7–S1 SVA decreased progressively across epochs (110.8 to 92.0 p=0.004).At 6 weeks, comparison of the mean demonstrated progressively larger L4–S1 lordosis (p<0.001), lower L1–S1 lordosis (p = 0.007), lower L1 pelvic angle (p=0.004), lower L1 pelvic angle offset from ideal (p=0.001), and greater T4–L1 pelvic angle (p<0.001). Concurrently, variance decreased over time for PI–LL mismatch (p=0.012), C7–S1 SVA (p=0.002), and L1 pelvic angle (p=0.02). In terms of correction, later epochs showed less change in PT (p=0.029), PI-LL mismatch (p=0.039), SVA (p=0.016), and T4L1PA (p<0.001) as well as greater change in L4-S1 (p=0.007). Additionally, the percentage of lumbar lordosis attributable to the distal segment (100 × L4–S1/LL) and the lordosis change attributable to the distal segment (100 × Δ[L4–S1]/Δ[LL]) increased across epochs. Severe radiographic PJK at 6 weeks progressively decreased across the epochs (10.5% vs 3.9%, p = 0.001). Satisfaction rates (SRS22r satisfaction median = 4.5; satisfaction ≥ 3.5 Epoch 1: 83%; Epoch 2: 80%; Epoch 3: 81%) and revision rates (Epoch 1: 20%; Epoch 2: 19%, Epoch 3: 14%) at 2 years did not significantly differ across epochs.Subgroup analysis showed similar evolution of sagittal alignment in upper thoracic and lower thoracic constructs, with the latter showing more focus on segmental lumbar lordosis in later epochs. CONCLUSIONS ASD alignment strategies have evolved, emphasizing distal LL restoration and reducing variability. While radiographic improvements are evident, satisfaction and revision rates have not significantly improved, highlighting a gap between radiographic and clinical outcomes. FDA Device/Drug Status This abstract does not discuss or include any applicable devices or drugs.