Faculty Bibliography

STUDY DESIGN/METHODS:Retrospective review of the prospectively enrolled, multicenter ASD database. OBJECTIVE:We sought to compare clinical and economic outcomes for ASD patients with poor-bone-health versus those with normal-bone-health. SUMMARY OF BACKGROUND DATA/BACKGROUND:Osteoporosis is a common comorbidity in the adult spinal deformity (ASD) population, with a reported prevalence of 14-29%. METHODS:Patients were categorized into five guideline-concordant cohorts: Confirmed-Osteoporosis (COP: patients with osteopenia or osteoporosis based on DEXA values or a formal preoperative diagnosis); Fracture Osteoporosis (Fx: patients with fragility fractures); Fracture-without-confirmed-Osteoporosis (FXNO: patients with fragility fractures but no osteopenia/osteoporosis diagnosis based on DEXA/formal documentation); Confirmed/fracture-osteoporosis (COP/FX: patients with fragility fractures and/or osteopenia/osteoporosis by DEXA/diagnosis); and the Normal cohort (Nm: patients with normal bone health and no fragility fractures). Cost analyses were performed using multivariate linear regression controlling for BMI, diabetes, baseline deformity (T1PA), and levels fused. Multivariate logistic regression assessed risk of reoperation/complications between groups while controlling for BMI, diabetes, baseline deformity (T1PA), and levels fused. RESULTS:Overall, 205 patients were included in the Fx-cohort, 136 patients in the COP-cohort, 115 patients in the FXNO-cohort, and 71 patients Nm-cohort. Compared with the Nm-cohort, osteoporotic-cohorts demonstrated significantly worse baseline spinopelvic alignment and higher comorbidity burden. Fx and FXNO cohorts had higher rates of PJF (Fx: 11.2% vs 1.4%, aOR 7.8; FXNO: 10.4% vs 1.4%, aOR 9.0) and revision surgery (Fx: 19.5% vs 7.0%, aOR 2.8; FXNO: 22.6% vs 7.0%, aOR 3.6). Osteoporotic cohorts demonstrated significantly higher short-term QALYs at 6 weeks (P<0.05) with no difference in the long term. Revision surgery averaged $95,117 per case, translating into an estimated $4.0 million potential-cost-savings. CONCLUSION/CONCLUSIONS:Our findings highlight the clinical and economic burden of untreated poor bone quality in the setting of ASD surgery. Proactive medical management is crucial to mitigate complications, reduce revisions, and significantly lower healthcare costs in ASD surgery.

AIMS/UNASSIGNED: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/UNASSIGNED: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/UNASSIGNED: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/UNASSIGNED: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.

STUDY DESIGN/METHODS:Multicenter retrospective cohort study of prospectively collected data. OBJECTIVE:Evaluate the impact of EOS-derived thigh muscle measurements as indicators of sarcopenia and their effect on compensatory mechanisms in adult spinal deformity (ASD) patients. SUMMARY OF BACKGROUND DATA/BACKGROUND:ASD patients frequently present with sarcopenia, the progressive loss of muscle strength and mass associated with worse postoperative outcomes. Routine EOS full-body radiographs allow opportunistic thigh muscle measurement without added cost or radiation. This study evaluated EOS-derived thigh and quadriceps thickness against clinical indicators of sarcopenia and their impact on compensatory mechanisms in ASD. METHODS:We retrospectively analyzed prospectively collected data from 24 U.S. and Canadian spine centers(2019-2024). Sarcopenia was defined using validated sex-specific EOS cutoffs. Patients were classified as sarcopenic only when both AP thigh and LAT quadriceps measurements fell below threshold. Clinical frailty scores, grip strength, 3-meter timed up and go(TUG), and epigenetic age were compared between sarcopenic(SARCO) and non-sarcopenic(NON-SARCO) patients. Multivariate regressions assessed associations between thigh measurements, sarcopenia status, and compensatory radiographic parameters. RESULTS:Among 540 ASD patients (mean age 60, 71% female), 61 (11.3%) were SARCO. SARCO patients had lower BMI(23.6 vs. 27.3 kg/m²), higher clinical frailty scores (3.4 vs. 3.0), and slower TUG (12.2 vs. 10.5s) (all P<0.05). Multivariate analyses showed smaller thigh and quadriceps thickness and sarcopenia status correlated with higher frailty, weaker grip, slower TUG, and older epigenetic age (all P<0.05). Sarcopenia was also associated with greater thoracic kyphosis (β=6.87, P<0.01), cervical lordosis (β=5.84, P=0.01), sagittal vertical axis (β=13.17, P=0.04), and knee flexion angle (β=2.29, P=0.04), but not pelvic tilt, shift, or sacro-femoral angle (all P>0.05). CONCLUSIONS:Full-body radiographic derived thigh measurements significantly correlate with frailty, grip strength, TUG, and epigenetic age. Sarcopenic ASD patients demonstrate impaired proximal and increased distal compensations. Incorporating thigh and quadriceps muscle thickness measurements into preoperative assessment may improve surgical planning and patient management in ASD. LEVEL OF EVIDENCE/METHODS:Prognostic Level III.

STUDY DESIGN/METHODS:Retrospective multicenter registry. OBJECTIVE:To establish a multidimensional definition of surgical success in ASD surgery and evaluate achievement rates across diverse patient subgroups. SUMMARY OF BACKGROUND DATA/BACKGROUND:Adult spinal deformity (ASD) encompasses diverse deformity types, disability levels, and treatment options. Optimal surgery aims in part to improve function, reduce radicular pain, and minimize revisions. Despite some studies considering combined outcomes, comprehensive multifactorial evaluation remains limited. METHODS:Success was assessed across disability (2-year ODI ≤20 or ∆ODI >14), radicular pain (NRS Leg ≤3 or ∆NRS Leg >3), and reoperation (no mechanical/neurologic revision). Patients were categorized by preoperative high disability (ODI >40) and/or high pain (NRS Leg >5). Individual and composite success rates were compared across preoperative deficits and deformity types. Satisfaction and treatment repetition willingness were analyzed by success achievement. RESULTS:Of 1,504 patients, 1,084 (71.9%) completed 2-year follow-up (median age 64 years, 75.4% female, 50.7% prior surgery). Median preoperative scores: ODI 44, NRS Back 8, NRS Leg 5. Preoperatively, 40.7% had combined high disability and pain, 21.6% high disability only, 13.5% high pain only, and 20.2% neither. At 2 years, success rates were 60.9% for disability, 64.8% for leg pain, 81.2% for revision avoidance, and 40.5% composite. Composite success was highest without preoperative deficits (59.4%), intermediate with isolated deficits (38.0% high disability, 43.8% high pain), and lowest with combined deficits (32.2%). Severe coronal deformities achieved highest composite success (51.7%) versus 32.0%-41.3% for other types. Composite success strongly correlated with satisfaction (87.2%) and willingness to repeat treatment (94.4%). CONCLUSIONS:Success in ASD surgery should reflect both improvement and final outcomes. Composite success measures provide more comprehensive surgical assessment than single metrics. By identifying patient characteristics associated with higher success rates, this framework informs evidence-based patient selection, enables realistic preoperative counseling, and guides outcome-driven surgical planning.

High-riding vertebral artery (HRVA) is an important anatomical variant of the vertebral artery that poses significant challenges during cervical spine surgery, particularly at the C1-C2 level, where it reduces the safe corridor for pedicle screw placement and increases the risk of arterial injury. This narrative review summarizes current evidence regarding the definition, prevalence, imaging identification, and surgical implications of HRVA, along with risk mitigation strategies. Radiographically, HRVA is most commonly defined by reduced C2 isthmus height (C2IsH) (≤5 mm) and/or internal height (C2InH) (≤2 mm) on computed tomography (CT) scans. Reported prevalence varies widely across populations, typically ranging from 10% to 25%, with higher rates observed in selected patient cohorts. The presence of HRVA necessitates careful perioperative planning, including comprehensive imaging and modification of surgical techniques, such as the use of alternative fixation strategies, including pars screws, laminar screws, navigation-assisted instrumentation, and artery mobilization. Advances in CT angiography (CTA), alternative fixation strategies, surgical navigation, and emerging predictive models may further improve risk stratification and operative safety. Recognition of HRVA and tailored surgical planning are essential to minimize the risk of vertebral artery injury (VAI) and to optimize patient outcomes in cervical spine surgery and instrumentation.

PURPOSE/OBJECTIVE:To evaluate the impact of thoracic spine degeneration in adult spinal deformity (ASD) patients on radiographic outcomes. METHODS:Primary ASD patients undergoing thoracolumbar fusion with T9-L1 upper instrumented vertebra (UIV) and S1/ilium lower instrumented vertebra were included. Thoracic spine degeneration was assessed radiographically using Kellgren-Lawrence (KL) grading and segmented into T1-T5, T5-T9, and T9-L1 arcs per Lafage criteria. Arc degeneration was defined as ≥ 2 levels with KL grade 3 + in an arc and thoracic spine degeneration as ≥ 1 degenerated arc. Proximal zone degeneration was KL grade 3 + in the two levels above the UIV and distal zone degeneration was KL grade 3 + in unfused thoracic levels outside the proximal zone. Patients with no degenerated levels served as controls. RESULTS:Among 272 patients (mean age 65.1years, 74% female, mean Charlson Comorbidity Index 1.9), 19, 81, and 100 patients had T1-T5, T5-T9, and T9-L1 arc degeneration, respectively, corresponding to 151 degenerated and 72 control patients. Degenerated patients exhibited higher thoracic kyphosis (36.1° vs. 27.6°), reduced expected thoracic compensation via hypokyphosis (- 0.7° vs. 8.8°), and higher lumbar lordosis (38.6° vs. 32.3°) (p < 0.05). At six weeks, degenerated patients had smaller reciprocal kyphotic changes (1.6° vs. 5.8°). At two years, they had higher proximal junctional kyphosis (PJK)-Normative rates (38% vs. 24%) (p < 0.05). Proximal zone sub-analysis showed that two-year PJK-Normative rates (43% vs. 32% vs. 24%) decreased incrementally from proximal to distal zone degeneration to controls (p < 0.05). CONCLUSION/CONCLUSIONS:Over half of ASD patients exhibited thoracic spine degeneration, predominantly in the lower arcs (T5-L1). This was associated with reduced thoracic hypokyphosis, smaller six-week reciprocal kyphotic changes, and higher two-year PJK rates. Proximal zone degeneration predicted junctional failure. Surgical planning should consider thoracic degeneration and compensatory mechanisms, with careful UIV selection to ensure sustained correction. LEVEL OF EVIDENCE/METHODS:IV.

OBJECTIVE:The aim of the study was to evaluate the safety and efficacy of initiating physical therapy (PT) on the day of surgery (i.e., postoperative day 0 [POD0]) in patients undergoing single-level lumbar fusion surgery, with a focus on hospital length of stay (LOS) and early postoperative outcomes. METHODS:The authors conducted a retrospective review of prospectively collected data from a single institution. Patients undergoing single-level lumbar fusion between August 2022 and December 2024 were included. Those with revision surgery, tumors, or infections were excluded. POD0 PT was implemented in January 2024. Patients treated prior to this date received POD1 PT. Demographic, surgical, and postoperative data were compared between the POD0 and POD1 PT groups. RESULTS:A total of 586 patients were analyzed (POD0, n = 84; POD1, n = 502). Baseline demographics and surgical characteristics were similar between the groups. The POD0 group had a significantly shorter LOS (mean 3.4 ± 1.6 vs 4.0 ± 2.7 days, p = 0.016), and the patients were more likely to be discharged home. No significant differences were found in postoperative complications, including cardiac, pulmonary, neurological, gastrointestinal, urinary, infectious, or mechanical issues. Rates of 30- and 90-day emergency department visits, readmissions, or reoperations were also comparable between the groups. CONCLUSIONS:Initiating PT on the day of surgery is associated with reduced LOS and an increased likelihood of home discharge, without increasing complications or worsening clinical outcomes. These findings support the safety and potential benefits of POD0 PT in enhancing early recovery following single-level lumbar fusion surgery.

STUDY DESIGN/METHODS:Prospective multicenter study. OBJECTIVE:To determine the incidence of all-cause mortality after adult spinal deformity surgery. SUMMARY OF BACKGROUND DATA/BACKGROUND: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. METHODS:Using 2 prospective, multicenter databases, we identified patients who underwent surgery for cervical deformity surgery from 2013-2020 (n=169) or thoracolumbar deformity from 2008-2020 (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±standard deviation age, 61±10 y), 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 90-day mortality rate was 1.2% (2/169). The 3 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±standard deviation age, 61±14 y), 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 3 most common causes of death were non-spine 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/METHODS:III.

STUDY DESIGN/METHODS:Retrospective single-center cohort study. OBJECTIVE:To evaluate whether preoperative CT-based finite element analysis (FEA) of vertebral bone modulus predicts bone quality-related complications after lumbar spine fusion. SUMMARY OF BACKGROUND DATA/BACKGROUND:In spine surgery patients, poor bone quality increases the risk of proximal junctional kyphosis/failure, pedicle screw loosening, adjacent segment disease, and pseudoarthrosis, leading to higher revision rates. DXA-based areal bone mineral density (BMD) often fails to identify high-risk patients, particularly in degenerative spines. Three-dimensional CT-based methods, such as Hounsfield units (HU), volumetric BMD, and CT-based FEA, may better capture vertebral mechanical competence by integrating density and microarchitecture. METHODS:Patients undergoing lumbar fusion at a single academic center in 2017 with ≥2-year follow-up were included (n=85) and classified by the presence of bone quality-related complications. For L1-L5 on preoperative CT, trabecular VOIs were analyzed to obtain mean HU, phantomless-calibrated BMD, and FEA-derived bone modulus. Group differences were assessed with independent-samples t tests, and ROC analysis and multivariable logistic regression examined associations with complication status. RESULTS:Thirty-one patients (36.5%) experienced ≥1 bone quality-related complication; 18 had ≥2 events. Bone modulus was significantly lower in the complication cohort (-15.7% to -23.2%; all p≤0.02), whereas HU and BMD differences were nonsignificant. Bone modulus showed greater ability to distinguish patients with and without complications (AUC 0.65-0.70; all P<0.03), while HU and BMD did not (AUC ~0.57-0.60; all P>0.10). Multivariable models including modulus, BMD, and demographics achieved AUC up to 0.81 at L5 (P<0.001). CONCLUSION/CONCLUSIONS:Preoperative CT-based FEA of vertebral bone modulus outperforms HU and BMD in identifying lumbar fusion patients at risk for bone quality-related complications and may provide a useful adjunct for preoperative risk stratification and surgical planning.

STUDY DESIGN/METHODS:Prospective, multicenter study. OBJECTIVE:To compare and characterize complications in adult spinal deformity (ASD) patients with and without 3-column osteotomy (3CO). SUMMARY OF BACKGROUND DATA/BACKGROUND:Although 3CO is associated with increased risk of neurologic adverse events, no study has, to our knowledge, compared and characterized sensory and motor neurologic complications in ASD patients with vs. without 3CO. MATERIALS AND METHODS/METHODS:Demographics, surgical characteristics, and neurologic complications were collected for 553 ASD patients. Lower extremity motor scores (LEMSs) were compared at baseline and postoperatively. Multivariate analysis was performed to identify risk factors associated with neurologic adverse events. RESULTS:Among 553 ASD patients, 130 (23.5%) underwent 3CO. More patients with 3CO were revision patients (67.7% vs. 35.0%; P<0.001), presented with sagittal deformity (43.9% vs. 31.0%; P=0.008), and had longer operative times (455.6 vs. 407.3 min; P=0.001) and greater estimated blood loss (EBL) (1,650 vs. 1,000 mL; P<0.001) than patients without 3CO. The incidence of neurologic adverse events was greater among patients with vs. without 3CO (23.1% vs. 15.4%; P=0.04). Multivariate analysis revealed that older age (odds ratio [OR] 1.288 per 10-year increase, 95% confidence interval [CI] 1.060-1.565, P=0.01) and longer operative time (OR 1.088, 95% CI 1.001-1.004, P=0.01) were significant predictors of neurologic adverse events. No between-group difference in LEMS was observed at 6-week (49.0 vs. 49.0; P=0.90) or 1-year (49.4 vs. 49.3; P=0.71) follow-up. By 1-year follow-up, 20.5% of 3CO patients and 21.6% of patients without 3CO had residual motor deficit. CONCLUSIONS:Compared with patients who did not undergo 3CO, more patients with 3CO had prior instrumentation, presented with sagittal deformity, had longer operative time and greater EBL, and were more likely to have a neurologic adverse event. At 1-year follow-up, there was no significant difference in LEMS between the two groups. LEVEL OF EVIDENCE/METHODS:III.