Faculty Bibliography

BACKGROUND:Hip osteoarthritis (OA) is common in patients with adult spinal deformity (ASD). Limited data exist on the prevalence of hip OA in patients with ASD, or on its impact on baseline and postoperative alignment and patient-reported outcome measures (PROMs). Therefore, this paper will assess the prevalence and impact of hip OA on alignment and PROMs. METHODS:Patients with ASD who underwent L1-pelvis or longer fusions were included. Two independent reviewers graded hip OA with the Kellgren-Lawrence (KL) classification and stratified it by severity into non-severe (KL grade 1 or 2) and severe (KL grade 3 or 4). Radiographic parameters and PROMs were compared among 3 patient groups: Hip-Spine (hip KL grade 3 or 4 bilaterally), Unilateral (UL)-Hip (hip KL grade 3 or 4 unilaterally), or Spine (hip KL grade 1 or 2 bilaterally). RESULTS:Of 520 patients with ASD who met inclusion criteria for an OA prevalence analysis, 34% (177 of 520) had severe bilateral hip OA and unilateral or bilateral hip arthroplasty had been performed in 8.7% (45 of 520). A subset of 165 patients had all data components and were examined: 68 Hip-Spine, 32 UL-Hip, and 65 Spine. Hip-Spine patients were older (67.9 ± 9.5 years, versus 59.6 ± 10.1 years for Spine and 65.8 ± 7.5 years for UL-Hip; p < 0.001) and had a higher frailty index (4.3 ± 2.6, versus 2.7 ± 2.0 for UL-Hip and 2.9 ± 2.0 for Spine; p < 0.001). At 1 year, the groups had similar lumbar lordosis, yet the Hip-Spine patients had a worse sagittal vertebral axis (SVA) measurement (45.9 ± 45.5 mm, versus 25.1 ± 37.1 mm for UL-Hip and 19.0 ± 39.3 mm for Spine; p = 0.001). Hip-Spine patients also had worse Veterans RAND-12 Physical Component Summary scores at baseline (25.7 ± 9.3, versus 28.7 ± 9.8 for UL-Hip and 31.3 ± 10.5 for Spine; p = 0.005) and 1 year postoperatively (34.5 ± 11.4, versus 40.3 ± 10.4 for UL-Hip and 40.1 ± 10.9 for Spine; p = 0.006). CONCLUSIONS:This study of operatively treated ASD revealed that 1 in 3 patients had severe hip OA bilaterally. Such patients with severe bilateral hip OA had worse baseline SVA and PROMs that persisted 1 year following ASD surgery, despite correction of lordosis. LEVEL OF EVIDENCE/METHODS:Prognostic Level III. See Instructions for Authors for a complete description of levels of evidence.

STUDYDESIGN/METHODS:Retrospective cohort study of a prospectively collected multi-center adult spinal deformity (ASD) database. OBJECTIVE:To compare staged procedures to same-day interventions and identify the optimal time interval between staged surgeries for treatment of ASD. BACKGROUND:Surgical intervention for ASD is invasive and complex procedure that surgeons often elect to perform on different days (staging). Yet, there remains a paucity of literature on the timing and effects of the interval between stages. METHODS:ASD patients with two-year (2Y) data undergoing an anterior/posterior (A/P) fusion to the ilium were included. Propensity score matching (PSM) was performed for number of levels fused, number of interbody devices, surgical approaches, number of osteotomies/three-column osteotomy (3CO), frailty, Oswestry Disability Index (ODI), Charlson Comorbidity Index (CCI), revisions, sagittal vertical axis (SVA), pelvic incidence-lumbar lordosis (PI-LL), and UIV to create balanced cohorts of Same-Day and Staged surgical patients. Staged patients were stratified by intervening time-period between surgeries, using quartiles. RESULTS:176 PSM patients were included. Median interval between A/P staged procedures was 3 days. Staged patients had greater operative time and lower ICU stays postop (P<0.05). At 2Y, staged compared to same day showed a greater improvement in T1 slope - cervical lordosis (TS-CL), C2 sacral slope (C2SS), and SRS-Schwab SVA (P<0.05). Staged patients had higher rates of minimal clinically-important difference (MCID) for 1Y SRS-Appearance and 2Y physical component summary (PCS) scores. Assessing different intervals of staging, patients at the 75th percentile interval showed greater improvement in 1Y SRS Pain and Total postop as well as SRS Activity, Pain, Satisfaction, and Total scores (P<0.05) compared to patients in lower quartiles. Compared to the 25th percentile, patients reaching the 50th percentile interval were associated with increased odds of improvement in Global Alignment and Proportion (GAP) score proportionality (9.3[1.6-53.2], P=0.01). CONCLUSIONS:This investigation is among the first to compare multicenter staged and same day surgery anterior/posterior adult spinal deformity patients fused to ilium using propensity-matching. Staged procedures resulted in significant improvement radiographically, reduced ICU admissions, and superior patient reported outcomes compared to same day procedures. An interval of at least three days between staged procedures is associated with superior outcomes in terms of GAP score proportionality.

PURPOSE/OBJECTIVE:To investigate the effect of a prehabilitation program on peri- and post-operative outcomes in adult cervical deformity (CD) surgery. METHODS:Operative CD patients ≥ 18 years with complete baseline (BL) and 2-year (2Y) data were stratified by enrollment in a prehabilitation program beginning in 2019. Patients were stratified as having undergone prehabilitation (Prehab+) or not (Prehab-). Differences in pre and post-op factors were assessed via means comparison analysis. Costs were calculated using PearlDiver database estimates from Medicare pay-scales. RESULTS:). Of these patients, 57 (49%) were classified as Prehab+. At baseline, groups were comparable in age, gender, BMI, CCI, and frailty. Surgically, Prehab+ were able to undergo longer procedures (p = 0.017) with equivalent EBL (p = 0.627), and shorter SICU stay (p < 0.001). Post-operatively, Prehab+ patients reported greater reduction in pain scores and greater improvement in quality of life metrics at both 1Y and 2Y than Prehab- patients (all p < 0.05). Prehab+ patients reported significantly less complications overall, as well as less need for reoperation (all p < 0.05). CONCLUSION/CONCLUSIONS:Introducing prehabilitation protocols in adult cervical deformity surgery may aid in improving patient physiological status, enabling patients to undergo longer surgeries with lessened risk of peri- and post-operative complications.

OBJECTIVE:Provide benchmarks for the rates of complications by type and timing. STUDY DESIGN/METHODS:Prospective multicenter database. BACKGROUND:Complication rates following adult spinal deformity (ASD) surgery have been previously reported. However, the interplay between timing and complication type warrants further analysis. METHODS:The data for this study were sourced from a prospective, multicenter ASD database. Date and type of complication were collected and classified into three severity groups (minor, major, major leading to reoperation). Only complications occurring before the 2-year visit were retained for analysis. RESULTS:Of the 1260 patients eligible for 2-year follow-up, 997 (79.1%) achieved 2-year follow-up. The overall complication rate was 67.4% (N=672). 247 patients (24.8%) experienced at least one complication on the day of surgery (including intra-operatively), 359 (36.0%) between post-op day 1 and 6 weeks post-op, 271 (27.2%) between 6 weeks and 1 one -year post-op, and finally 162 (16.3%) between 1 year and 2 years post-op. Using Kaplan-Meier survival analysis, the rate of remaining complication-free was estimated at different time points for different severities and types of complications. Stratification by type of complication demonstrated that most of the medical complications occurred within the first 60 days. Surgical complications presented over two distinct timeframes. Operative complications, incision-related complications, and infections occurred early (within 60 d), while implant-related and radiographic complications occurred at a constant rate over the 2-year follow-up period. Neurologic complications had the highest occurrence within the first 60 days but continued to increase up to the 2-year visit. CONCLUSION/CONCLUSIONS:Only one-third of ASD patients remained complication-free by 2 years, and 2 out of 10 patients had a complication requiring a reoperation or revision. Estimation of timing and type of complication associated with surgical treatment may prove useful for more meaningful patient counseling and aid in assessing the cost-effectiveness of treatment.

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

OBJECTIVE:Sagittal alignment measured on standing radiography remains a fundamental component of surgical planning for adult spinal deformity (ASD). However, the relationship between classic sagittal alignment parameters and objective metrics, such as walking time (WT) and grip strength (GS), remains unknown. The objective of this work was to determine if ASD patients with worse baseline sagittal malalignment have worse objective physical metrics and if those metrics have a stronger relationship to patient-reported outcome metrics (PROMs) than standing alignment. METHODS:The authors conducted a retrospective review of a multicenter ASD cohort. ASD patients underwent baseline testing with the timed up-and-go 6-m walk test (seconds) and for GS (pounds). Baseline PROMs were surveyed, including Oswestry Disability Index (ODI), Patient-Reported Outcomes Measurement Information System (PROMIS), Scoliosis Research Society (SRS)-22r, and Veterans RAND 12 (VR-12) scores. Standard spinopelvic measurements were obtained (sagittal vertical axis [SVA], pelvic tilt [PT], and mismatch between pelvic incidence and lumbar lordosis [PI-LL], and SRS-Schwab ASD classification). Univariate and multivariable linear regression modeling was performed to interrogate associations between objective physical metrics, sagittal parameters, and PROMs. RESULTS:In total, 494 patients were included, with mean ± SD age 61 ± 14 years, and 68% were female. Average WT was 11.2 ± 6.1 seconds and average GS was 56.6 ± 24.9 lbs. With increasing PT, PI-LL, and SVA quartiles, WT significantly increased (p < 0.05). SRS-Schwab type N patients demonstrated a significantly longer average WT (12.5 ± 6.2 seconds), and type T patients had a significantly shorter WT time (7.9 ± 2.7 seconds, p = 0.03). With increasing PT quartiles, GS significantly decreased (p < 0.05). SRS-Schwab type T patients had a significantly higher average GS (68.8 ± 27.8 lbs), and type L patients had a significantly lower average GS (51.6 ± 20.4 lbs, p = 0.03). In the frailty-adjusted multivariable linear regression analyses, WT was more strongly associated with PROMs than sagittal parameters. GS was more strongly associated with ODI and PROMIS Physical Function scores. CONCLUSIONS:The authors observed that increasing baseline sagittal malalignment is associated with slower WT, and possibly weaker GS, in ASD patients. WT has a stronger relationship to PROMs than standing alignment parameters. Objective physical metrics likely offer added value to standard spinopelvic measurements in ASD evaluation and surgical planning.

STUDY DESIGN/METHODS:Retrospective review of prospectively collected data. OBJECTIVE:To investigate the effect of lower extremity osteoarthritis on sagittal alignment and compensatory mechanisms in adult spinal deformity (ASD). BACKGROUND:Spine, hip, and knee pathologies often overlap in ASD patients. Limited data exists on how lower extremity osteoarthritis impacts sagittal alignment and compensatory mechanisms in ASD. METHODS:527 pre-operative ASD patients with full body radiographs were included. Patients were grouped by Kellgren-Lawrence grade of bilateral hips and knees and stratified by quartile of T1-Pelvic Angle (T1PA) severity into low-, mid-, high-, and severe-T1PA. Full body alignment and compensation were compared across quartiles. Regression analysis examined the incremental impact of hip and knee osteoarthritis severity on compensation. RESULTS:The mean T1PA for low-, mid-, high-, and severe-T1PA groups was 7.3°, 19.5°, 27.8°, 41.6°, respectively. Mid-T1PA patients with severe hip osteoarthritis had an increased sagittal vertical axis and global sagittal alignment (P<0.001). Increasing hip osteoarthritis severity resulted in decreased pelvic tilt (P=0.001) and sacrofemoral angle (P<0.001), but increased knee flexion (P=0.012). Regression analysis revealed with increasing T1PA, pelvic tilt correlated inversely with hip osteoarthritis and positively with knee osteoarthritis (r2=0.812). Hip osteoarthritis decreased compensation via sacrofemoral angle (β-coefficient=-0.206). Knee and hip osteoarthritis contributed to greater knee flexion (β-coefficients=0.215, 0.101; respectively). For pelvic shift, only hip osteoarthritis significantly contributed to the model (β-coefficient=0.100). CONCLUSIONS:For the same magnitude of spinal deformity, increased hip osteoarthritis severity was associated with worse truncal and full body alignment with posterior translation of the pelvis. Patients with severe hip and knee osteoarthritis exhibited decreased hip extension and pelvic tilt, but increased knee flexion. This examines sagittal alignment and compensation in ASD patients with hip and knee arthritis and may help delineate whether hip and knee flexion is due to spinal deformity compensation or lower extremity osteoarthritis.

OBJECTIVE:Recent debate has arisen between whether to use a three-column osteotomy (3CO) or multilevel low-grade (MLG) techniques to treat severe sagittal malalignment in adult spinal deformity (ASD) surgery. The goal of this study was to compare the outcomes of 3CO and MLG techniques performed in corrective surgeries for ASD. METHODS:ASD patients who had a baseline PI-LL > 30° and 2-year follow-up data were included. Patients underwent either 3CO or MLG (thoracolumbar posterior column osteotomies at ≥ 3 levels or anterior lumbar interbody fusion at ≥ 3 levels with no 3CO). The segmental utility ratio was used to assess relative segmental correction (segmental correction divided by overall correction in lordosis divided by the number of thoracolumbar interventions [interbody fusion, thoracolumbar posterior column osteotomies, and 3CO]). The paired t-test was used to assess lordotic distribution by differences in lordosis between adjacent lumbar disc spaces (e.g., L1-2 to L2-3). Multivariate analysis, controlling for age, sex, BMI, osteoporosis, baseline pelvic incidence, and T1 pelvic angle, was used to evaluate the complication rates and radiographic and patient-reported outcomes between the groups. RESULTS:A total of 93 patients were included, 53% of whom underwent MLG and 47% of whom underwent 3CO. The MLG group had a lower BMI (p < 0.05). MLG patients received fewer previous fusions than 3CO patients (31% vs 80%, p < 0.001). MLG patients had 24% less blood loss but a 22% longer operative time (565 vs 419 minutes, p = 0.008). Using adjusted analysis, the 3CO group had greater segmental and relative correction at each level (segmental utility ratio mean 69% for 3CO vs 23% for MLG, p < 0.001). However, the 3CO group had lordotic differences between two adjacent lumbar disc pairs (range -0.5° to 9.0°, p = 0.009), while MLG was more harmonious (range 2.2°-6.5°, p > 0.4). MLG patients were more likely to undergo realignment to age-adjusted standards (OR 5.6, 95% CI 1.2-46.4; p = 0.033). MLG patients were less likely to develop neurological complications or undergo reoperation (OR 0.4, 95% CI 0.1-0.9; p = 0.041). Adjusted analysis revealed that MLG patients more often met a substantial clinical benefit in the Oswestry Disability Index score (OR 5.3, 95% CI 1.1-26.8; p = 0.043). CONCLUSIONS:MLG techniques showed better utility in lumbar distribution and age-adjusted global correction while minimizing neurological complications and reoperation rates by 2 years postoperatively. In selected instances, these techniques may offer the spine deformity surgeon a safer alternative when correcting severe adult spinal deformity.

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