Faculty Bibliography

STUDY DESIGN/METHODS: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:< .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.

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/METHODS:Therapeutic Level III. See Instructions for Authors for a complete description of levels of evidence.

STUDY DESIGN/METHODS:Retrospective review. OBJECTIVES/OBJECTIVE: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.

STUDY DESIGN/METHODS:Retrospective analysis of prospectively collected data. OBJECTIVE:To investigate the effect of the approach of the transforaminal lumbar interbody fusion [TLIF; open vs . minimally invasive (MIS)] on reoperation rates due to ASD at 2 to 4-year follow-up. SUMMARY OF BACKGROUND DATA/BACKGROUND:Adjacent segment degeneration is a complication of lumbar fusion surgery, which may progress to adjacent segment disease (ASD) and cause debilitating postoperative pain potentially requiring additional operative management for relief. MIS TLIF surgery has been introduced to minimize this complication but the impact on ASD incidence is unclear. MATERIALS AND METHODS/METHODS:For a cohort of patients undergoing 1 or 2-level primary TLIF between 2013 and 2019, patient demographics and follow-up outcomes were collected and compared among patients who underwent open versus MIS TLIF using the Mann-Whitney U test, Fischer exact test, and binary logistic regression. RESULTS:Two hundred thirty-eight patients met the inclusion criteria. There was a significant difference in revision rates due to ASD between MIS and open TLIFs at 2 (5.8% vs . 15.4%, P =0.021) and 3 (8% vs . 23.2%, P =0.03) year follow-up, with open TLIFs demonstrating significantly higher revision rates. The surgical approach was the only independent predictor of reoperation rates at both 2 and 3-year follow-ups (2 yr, P =0.009; 3 yr, P =0.011). CONCLUSIONS:Open TLIF was found to have a significantly higher rate of reoperation due to ASD compared with the MIS approach. In addition, the surgical approach (MIS vs . open) seems to be an independent predictor of reoperation rates.

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.

BACKGROUND CONTEXT: Complex spinal deformity surgeries may involve significant blood loss. The use of antifibrinolytic agents such as tranexamic acid (TXA) has proven to reduce perioperative blood loss. However, for patients with a history of thromboembolic events (TE) there exists a concern of increased postoperative TE after the use of TXA during complex spinal deformity surgeries. PURPOSE: This study aimed to assess whether TXA use in patients undergoing complex spinal deformity correction surgeries increased the risk of TE complications based on their pre-existing TE risk factors. STUDY DESIGN/SETTING: A prospective, multicenter, case-control study. PATIENT SAMPLE: A total of 461 consecutive patients who underwent complex spinal deformity surgery and received TXA. OUTCOME MEASURES: Thromboembolic complication rates of deep venous thrombosis (DVT), pulmonary embolism (PE), cerebrovascular accident (CVA) or stroke, and acute myocardial infarction (AMI). METHODS: All complex spinal deformity patients that underwent surgical correction and received TXA between August 2018 and October 2022 in 21 centers were analyzed. Patients with pre-existing TE risk factors were identified (history of DVT, PE, MI, CVA, PVD, cancer). The rates of thromboembolic complications were assessed during the postoperative 90 days. Univariate analysis was done to assess the thromboembolic outcomes after using TXA in high-risk patients. RESULTS: There was no significant difference in thromboembolic complications between patients who received TXA (regardless of pre-existing TE risk factors) in the univariate analysis (high-risk group [HR]=5.9%, control[c]= 2.9%; p=0.12) based on 461 consecutive patients who underwent complex spinal deformity surgery and received TXA. Specifically, there were no significant differences between groups regarding the 90-day postoperative DVT (HR=1.4%, c=0.8%; p=0.59), PE (HR=2.7%, c=1.3%; p=0.26), AMI (HR=0.9%, c=0.4%; p=0.51), nor CVA (HR=1.4%, c= 0.8%;p=0.59). EBL (HR=1668 ml, c=1492ml; p=0.19) and transfusion rates (HR=2.1 units, c=1.81 units; p=0.21) were similar between the two groups. CONCLUSIONS: High-risk patients undergoing spinal deformity surgery did not have an increase in TE after TXA as compared to others receiving TXA. FDA Device/Drug Status: This abstract does not discuss or include any applicable devices or drugs.

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/METHODS: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/BACKGROUND: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.

STUDY DESIGN/METHODS:Retrospective analysis of a prospectively collected multicenter database. OBJECTIVE:The objective of this study was to assess the radiographic and health-related quality of life (HRQoL) impact of a short-term (<1 y) return to the operating room (OR) after adult cervical spine deformity (ACSD) surgery. SUMMARY OF BACKGROUND DATA/BACKGROUND:Returns to the OR within a year of ACSD correction can be particularly devastating to these vulnerable hosts as they often involve compromise of the soft tissue envelope, neurological deficits, or hardware failure. This work sought to assess the impact of a short-term reoperation on 1-year radiographic and HRQoL outcomes. MATERIALS AND METHODS/METHODS:Patients operated on from January 1, 2013, to January 1, 2019, with at least 1 year of follow-up were included. The primary outcome was a short-term return to the OR. Variables of interest included patient demographics, Charlson Comorbidity Index, HRQoL measured with the modified Japanese Orthopaedic Association), Neck Disability Index, and EuroQuol-5D Visual Analog Scale (EQ-5D VAS) and radiographic outcomes, including T1 slope, C2-C7 sagittal Cobb angle, T1 slope-Cobb angle, and cervical sagittal vertical axis. Comparisons between those who did versus did not require a 1-year reoperation were performed using paired t tests. A Kaplan-Meier survival curve was used to estimate reoperation-free survival up to 2 years postoperatively. RESULTS:A total of 121 patients were included in this work (age: 61.9±10.1 yr, body mass index: 28.4±6.9, Charlson Comorbidity Index: 1.0±1.4, 62.8% female). A 1-year unplanned return to the OR was required for 28 (23.1%) patients, of whom 19 followed up for at least 1 year. Indications for a return to the OR were most commonly for neurological complications (5%), infectious/wound complications (5.8%), and junctional failure (6.6%) No differences in demographics, comorbidities, preoperative or 1-year postoperative HRQoL, or radiographic outcomes were seen between operative groups. CONCLUSION/CONCLUSIONS:Reoperation <1 year after ACSD surgery did not influence 1-year radiographic outcomes or HRQoL.

OBJECTIVE:The objective of this study was to evaluate spinopelvic sagittal alignment and spinal compensatory changes in adult cervical kyphotic deformity. METHODS:A database composed of 13 US spine centers was retrospectively reviewed for adult patients who underwent cervical reconstruction with radiographic evidence of cervical kyphotic deformity: C2-7 sagittal vertical axis > 4 cm, chin-brow vertical angle > 25°, or cervical kyphosis (T1 slope [T1S] cervical lordosis [CL] > 15°) (n = 129). Sagittal parameters were evaluated preoperatively and in the early postoperative window (6 weeks to 6 months postoperatively) and compared with asymptomatic control patients. Adult cervical deformity patients were further stratified by degree of cervical kyphosis (severe kyphosis, C2-T3 Cobb angle ≤ -30°; moderate kyphosis, ≤ 0°; and minimal kyphosis, > 0°) and severity of sagittal malalignment (severe malalignment, sagittal vertical axis T3-S1 ≤ -60 mm; moderate malalignment, ≤ 20 mm; and minimal malalignment > 20 mm). RESULTS:Compared with asymptomatic control patients, cervical deformity was associated with increased C0-2 lordosis (32.9° vs 23.6°), T1S (33.5° vs 28.0°), thoracolumbar junction kyphosis (T10-L2 Cobb angle -7.0° vs -1.7°), and pelvic tilt (PT) (19.7° vs 15.9°) (p < 0.01). Cervicothoracic kyphosis was correlated with C0-2 lordosis (R = -0.57, p < 0.01) and lumbar lordosis (LL) (R = -0.20, p = 0.03). Cervical reconstruction resulted in decreased C0-2 lordosis, increased T1S, and increased thoracic and thoracolumbar junction kyphosis (p < 0.01). Patients with severe cervical kyphosis (n = 34) had greater C0-2 lordosis (p < 0.01) and postoperative reduction of C0-2 lordosis (p = 0.02) but no difference in PT. Severe cervical kyphosis was also associated with a greater increase in thoracic and thoracolumbar junction kyphosis postoperatively (p = 0.01). Patients with severe sagittal malalignment (n = 52) had decreased PT (p = 0.01) and increased LL (p < 0.01), as well as a greater postoperative reduction in LL (p < 0.01). CONCLUSIONS:Adult cervical deformity is associated with upper cervical hyperlordotic compensation and thoracic hypokyphosis. In the setting of increased kyphotic deformity and sagittal malalignment, thoracolumbar junction kyphosis and lumbar hyperlordosis develop to restore normal center of gravity. There was no consistent compensatory pelvic retroversion or anteversion among the adult cervical deformity patients in this cohort.