Faculty Bibliography

PURPOSE/OBJECTIVE:To determine whether changes in intraoperative neuromonitoring with saphenous nerve somatosensory evoked potential (SSEP) stimulation, preoperative assessment of  lumbar plexus location, and screw placement, are associated with thigh paresthesia development following an anterior-to-the-psoas (ATP) approach for vertebral body tethering (VBT) in adolescent idiopathic scoliosis (AIS) patients. METHODS:39 patients who underwent a thoracoabdominal ATP approach for VBT with a minimum 2-year follow-up were included. Neurologic monitoring variables, including saphenous nerve SSEPs and quadriceps motor evoked potentials (MEPs), psoas location, an indicator of lumbar plexus location, and screw placement were compared between patients with and without postoperative thigh paresthesia. Demographics and outcomes were analyzed using the Mann-Whitney U test and Fisher's exact test as appropriate, with statistical significance set at p < 0.05. RESULTS:41% of patients experienced postoperative thigh paresthesia. Additionally, 10% reported transient thigh numbness. No patients developed motor deficits. Lumbar plexus position and screw distance did not significantly differ between groups, and no neuromonitoring alarms occurred during psoas retraction. Although changes in quadriceps MEPs were not statistically associated with postoperative sensory symptoms, a higher proportion of patients with paresthesia demonstrated MEP changes (50% vs 19%, p = 0.063) and decreased MEP amplitudes (31% vs 13%, p = 0.077), representing a directional difference. All sensory symptoms resolved without intervention at a mean of 5.3 ± 5.6 weeks and a median of 2.5 (IQR 1-10). CONCLUSION/CONCLUSIONS:Changes in intraoperative neuromonitoring with saphenous nerve SSEP stimulation, psoas location, and screw positioning were not statistically associated with postoperative thigh paresthesia following the ATP approach for VBT in AIS patients. However, a directional difference was observed between quadriceps MEP changes and postoperative thigh paresthesia. These findings highlight the complexity of neurologic responses and support further investigation into patient-specific anatomy, surgical technique, and optimization of neuromonitoring strategies.

BACKGROUND AND OBJECTIVES/OBJECTIVE:Anterior lumbar interbody fusion (ALIF) is an important technique offering biomechanical advantages including improved disk height restoration, correction of sagittal and coronal imbalance, and improved fusion. Although generally safe, vascular injury remains a serious complication. Specific vascular injury mechanisms, management, and outcomes are insufficiently reported. We seek to better characterize the incidence, mechanism, management, and sequelae of intraoperative vascular injuries during ALIF. METHODS:We performed a retrospective single-center study of adult patients undergoing ALIF between 2018 and 2022. All exposures were performed by a vascular surgeon. Data analyzed included patient demographics, operative characteristics, and vascular complications (classified as major or minor). The primary outcomes were the incidence of vascular injury and postoperative venous thromboembolism (VTE). Statistical analyses included χ2 testing and logistic regression. RESULTS:Of 418 patients, 26 (6.2%) sustained intraoperative vascular injuries, with 4 (1.0%) classified as major. Injuries were predominantly venous (n = 25), most frequently involving the left common iliac vein during L4-L5 exposure. One arterial dissection required stenting. Postoperative VTE occurred in 11 patients (2.6%); notably, 45.5% of these patients had sustained an intraoperative vascular injury. Vascular injury was a strong independent predictor of VTE (odds ratio [OR]: 15.9; P < .001; 95% CI: 4.3-58.8). The number of levels fused was significantly associated with both vascular injury (OR: 1.76; P = .007; 95% CI: 1.16-2.66) and VTE (OR: 1.91; P = .031; 95% CI: 1.03-3.42). No association was found between vascular complications and previous abdominal surgery, body mass index, revision surgery, age older than 50, spinal deformity, or sex. There was 0% perioperative mortality. CONCLUSION/CONCLUSIONS:Vascular complications during ALIF are infrequent but significantly elevate the risk of postoperative VTE. Injuries cluster at the L4-L5 level and often involve the left common iliac vein. Preoperative planning, careful surgical technique, and experienced vascular access support are critical to minimizing complications.

OBJECTIVE:Adult spinal deformity (ASD) surgery patients maintain upright posture by using numerous compensatory mechanisms. The distribution of this compensation throughout the skeleton has not been fully investigated. METHODS:Patients with lumbar deformity curves undergoing fusion from T10 to the pelvis were included. Groups were stratified by Scoliosis Research Society (SRS)-Schwab sagittal deformity severity (mild, moderate, and severe). Compensation was determined based on the published values of asymptomatic individuals by Bao et al. (2018), with patients outside 1 standard deviation of the mean values deemed to be compensating. Adequate deformity correction was determined based on matching published sagittal age-adjusted score (SAAS) criteria. Means comparisons tests assessed differences between cohorts at each time point. RESULTS:In total, 379 ASD patients were included (mean age 66.7 ± 10.2 years, body mass index 28.4 ± 5.4 kg/m2, Charlson Comorbidity Index 1.20 ± 1.73). In total, 23.8% of patients had mild deformity, 19.2% moderate, and 57% severe. The severe deformity cohort generally demonstrated the highest rates of compensation across all regions at different time points. At baseline, the severe and moderate cohorts demonstrated predominantly lower limb-dominant compensation, with the highest frequencies of compensation seen at the knee and pelvis. In the mild cohort, knee compensation was relieved by 1 year when adequate correction was achieved. For the moderate cohort, hip and pelvic compensation were relieved first, with knee compensatory relief occurring by 2 years. For the severe cohort, pelvic compensation was relieved first, with global lower limb and thoracic compensation subsequently occurring. CONCLUSIONS:There is notable variation in how ASD patients compensate as the severity of their deformity progresses. There is also variation in how these patterns are altered postoperatively.

STUDY DESIGN/METHODS:Retrospective review of multicenter, prospective cervical deformity database. OBJECTIVE:To compare outcomes of extension of fusion to the cervical spine versus the upper thoracic (UT) spine. SUMMARY OF BACKGROUND DATA/BACKGROUND:Proximal junctional kyphosis (PJK) management after thoracolumbar fusion requires extension of fusion to the proximal spinal segments. Unlike extensions to the less mobile thoracic segments, crossing the cervicothoracic junction (CTJ) involves more mobile cervical segments and creates different biomechanical influences and clinical outcomes. No study has compared the outcomes of extending fusion to the cervical versus the UT spine. METHODS:Patients with thoracic PJK who underwent revision with extension of fusion to either the cervical or UT (T1 or T2) spine were identified in a multicenter, prospective cervical deformity database. Patients with cervical upper instrumented vertebra (UIV) were subdivided into lower cervical (LC; C4-7) and upper cervical (UC; and occiput-C3) groups. Baseline demographics, surgical variables, radiographic outcomes, 2-year health-related quality-of-life scores, complications, and revision rates were analyzed. RESULTS:Fifty-one patients (mean age: 60.4±12.9 y; 91% female) with at least 2 years of follow-up were included. Twelve had extension to the UT, 20 to the LC, and 19 to the UC spine. Demographic data, Charlson Comorbidity Index, follow-up duration, surgical parameters, radiographic measurements, recurrent PJK and reoperation rates, and 2-year patient-reported outcome scores were similar across groups. The instrumentation failure rate was higher in the LC (25%) than in the UT (0%) and UC (8%) groups (P=0.03). CONCLUSIONS:Stopping fusion at T1 or T2 did not result in greater complication or reoperation rates than extending to the cervical spine. The instrumentation-related complication rate was higher for extension to the LC than to the UC or UT spine. Crossing the CTJ should be individualized, but may not prevent additional proximal junctional-level problems in the management of thoracolumbar fusion PJK. LEVEL OF EVIDENCE/METHODS:Level IV.

OBJECTIVE:To evaluate the feasibility of same-day (postoperative day 0; POD0) physical therapy (PT) following lumbar fusion and to identify factors associated with failure to participate. METHODS:This retrospective study analyzed prospectively collected data from patients undergoing single-level posterior spinal fusion (PSF), with or without anterior (ALIF) or lateral (LLIF) interbody fusion, between January and December 2024 at a single institution. A standardized POD0 PT protocol was implemented for eligible patients. Patients were categorized into two groups: successful POD0 PT (ambulatory on POD0) and unable to participate. Demographic and surgical variables were compared between groups. Reasons for inability to participate were recorded and categorized. RESULTS:Among 129 patients in whom POD0 PT was attempted, 84 (65%) successfully participated, while 45 (35%) were unable. There were no significant differences in age, sex, BMI, ASA class, operative time, estimated blood loss, or surgical approach between groups. Patients who successfully completed POD0 PT had a significantly shorter hospital length of stay compared to those who did not (3.4 ± 1.6 vs 5.8 ± 2.9 days, P < 0.001), with no differences in complication rates, discharge disposition, emergency department visits, or reoperation rates. The most common barriers to POD0 PT were postoperative pain, medical issues (e.g., orthostatic hypotension, nausea, dizziness), and anesthesia-related somnolence. Less common factors included postoperative restrictions and logistical issues such as brace availability. CONCLUSIONS:POD0 PT following lumbar fusion is feasible in the majority of patients and is associated with a shorter hospital stay without increased complications. Failure to participate was not associated with the baseline patient or surgical characteristics evaluated in this study. Instead, the most common barriers were postoperative pain, transient medical issues, and anesthesia-related somnolence, suggesting that optimization of modifiable perioperative factors may improve the implementation of POD0 PT.

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.