Faculty Bibliography

BACKGROUND CONTEXT: Spinal and body balance are active processes requiring a thorough understanding of the harmony between static posture and dynamic motion. Our understanding of patients' function is lacking a more objective and quantified mechanism of assessment. The Dubousset Functional Test (DFT) is a four-component, novel, multidomain physical function and balance assessment proposed by Dr. Jean Dubousset. PURPOSE: To identify normative baseline/reference values for DFT in asymptomatic, healthy subjects, establish test feasibility, and identify correlations between demographics and DFT performance in the general population. STUDY DESIGN/SETTING: Prospective single-center. PATIENT SAMPLE: Sixty-five asymptomatic volunteers (mean age: 42.4+/-15.4 years; 42% female, mean BMI 26+/-4.8kg/m2). OUTCOME MEASURES: Demographics, DFT components: Up-and-Walking Test (UWT), Steps Test (ST), Down-and-Sitting Test (DST), Dual-Tasking Test (DTT).
METHOD(S): Asymptomatic volunteers were screened and recruited to participate in the 4 DFT components at a single center from 2017-2018. These include: (1) UWT (Up-and-Walking Test): unassisted sit-to-stand, walk forward/backward 5 m (no turn), unassisted sit; (2) ST (Steps Test): ascend 3 steps, turn, descend 3 steps; (3) DST (Down-and-Sitting Test): stand-to-ground sit-to-stand, assistance as needed; (4) DTT (Dual-Tasking Test): walk 5 m forth and back while counting down from 50 by 2. All subjects were given standardized verbal instructions and a physical demonstration for each DFT test. Trials were video recorded and timed, with scores assigned by time required to complete the test. All trials were conducted and all tests were scored by the same rater. Univariate and multivariate analysis were utilized to analyze durations of test components against demographics.
RESULT(S): 65 subjects were included (mean age, 42.4+/-15.4 years); 42% were female, and mean BMI was 26+/-4.8 kg/m^2. The racial breakdown of the cohort was 34% White, 25% Black, 15% Asian, 9% Indian, 6% Latino, 10% other. Evaluating the four components of the DFT, the mean and standard deviations of each test component were as follows: mean duration in seconds and 95% confidence interval of each DFT test: UWT: 14.8s (14.0-15.6s), ST: 6.3s (6.0-6.6s), DST: 6.0s (5.4-6.6s), and DTT: 12.8s (12.1-13.6s). There were no differences between males and females in time taken to perform any of the tests. There were significant correlations between age and DST (r=0.529), UWT (r=0.429), and ST (r=0.356) (all p<0.05), with no correlation found with DTT. A similar trend was found with respect to correlation with BMI (r=0.372, r=0.289, and r=0.366, p<0.05), with no correlation again found with DTT. With respect to DTT specifically, patients on average finished countdown from 50 to 29.7+/-5.3. 12.3% of subjects exhibited physical pausing during the DTT, and 87.5% of those were pauses occurred while turning. Among total subjects, 32.3% exhibited verbal pausing/stuttering/mistakes in counting during the Dual Tasking test; of these, 62% occurred while turning.
CONCLUSION(S): The DFT is a quick and feasible test that was performed safely in a cohort of healthy subjects. Age and BMI, but not gender, were found to influence all DFT tests. Physical and verbal pausing were reported in about 1/10 and 1/3 patients, respectively, with the majority of pausing occurring during the turning phase of the test. Utilization of this test in patients with spinal pathologies may help us to determine the offset from norms as well as understand the impact of preoperative DFT performance on surgical outcomes. FDA DEVICE/DRUG STATUS: This abstract does not discuss or include any applicable devices or drugs.
Copyright

BACKGROUND CONTEXT: Osteoporosis (OP) is a common condition affecting nearly 200 million individuals globally. Similarly, adult spinal deformity has a peak prevalence of 65% of the adult population. While bone health is instrumental in orthopaedic surgery, few studies have described the long-term outcomes of osteoporosis following surgery for ASD. PURPOSE: We sought to evaluate the impact of OP on two-year postoperative complication rates when compared to patients without OP. STUDY DESIGN/SETTING: Retrospective cohort study. PATIENT SAMPLE: Utilizing the New York State Statewide Planning and Research Cooperative System (SPARCS), we identified all patients who underwent >=4-level fusion with ICD-9 codes diagnostic for ASD (progressive idiopathic scoliosis and degenerative lumbar disease) from 2009-2011 with >=2-year follow-up. Patients with osteoporosis (OP) and without OR were identified following exclusions. OUTCOME MEASURES: Patient demographics, hospital-related parameters, postoperative complications and reoperations.
METHOD(S): Using SPARCS, we identified all patients who underwent >=4-level fusion with ICD-9 codes diagnostic for ASD (progressive idiopathic scoliosis and degenerative lumbar disease) from 2009-2011 for >=2-year minimum follow-up. Patients with osteoporosis (OP) and without OP were identified. Any patients with bone mineralization disorders (osteomalacia, rickets, hyperparathyroidism [primary, secondary, tertiary], vitamin D deficiency) and other systemic (fibrous dysplasia, sickle cell disease, renal osteodystrophy) and endocrine disorders (thyroid hypo- or hyperfunctioning disorders, adrenal insufficiency, adrenal hyperplastic syndromes) affecting bone quality or production were excluded, as were patients with surgical indications of trauma, systemic disease, infection, or cancer. The two cohorts were compared for demographics, hospital-related parameters, and 2-year postoperative complications and reoperations. Multivariate binary stepwise logistic regressions was utilized to identify significant predictors of these outcomes (covariates: OP, age, sex, race, and Charlson/Deyo).
RESULT(S): A total of 6,132 patients were identified (OP, n=490 (7.99%); No-OP, n=5,642). OP patients were older (67.6 vs 56.7 years), more often female (83.7% vs 46.2%) and white (84.3% vs 79.1%), and had higher comorbidity scores (Charlson/Deyo: 0.72 vs 0.61), all p<0.05. Patients with OP incurred higher hospital charges ($122,801 vs $108,649) and length of stay (6.7 days vs 5.8 days), both p<0.001. OP patients had higher rates of postop wound complications (13.5% vs 10.6%), acute renal failure (12.2% vs 7.90%), pseudarthrosis (3.7% vs 1.4%), blood transfusions (54.3% vs 34.6%), pneumonia (10.4% vs 6.1%), and implant-related complications (22.4% vs 14.5%); all p<=0.047. Patients in OP and no-OP cohorts experienced similar rates of postop PE, DVT, acute myocardial infarction, pneumonia, UTIs, dural tears, and CNS complications. Regression revealed that while controlling for demographics and comorbidities, OP is independently associated with increased odds of 2-year medical complications (OR=1.46), surgical complications (OR=1.55), and reoperations (OR=1.46); all p<=0.024.
CONCLUSION(S): Osteoporosis was associated with two-year postoperative complications in ASD patients. Aside from being an etiology of ASD due to vertebral fracture, osteoporosis should be considered as a comorbidity that needs to be optimized and managed perioperatively. Furthermore, this data is a call to every spine surgeon to consider metabolic bone disorders screening prior to any spinal deformity surgery. FDA DEVICE/DRUG STATUS: This abstract does not discuss or include any applicable devices or drugs.
Copyright

MINI: A retrospective analysis of the impact of PD on long-term outcomes following adult spinal deformity surgery with two-year follow-up surveillance in New York. PD patients experienced comparable overall complication and revision rates to a propensity score-matched patient cohort without PD from the general population undergoing thoracolumbar fusion surgery.

Background/UNASSIGNED:Full-body stereographs for adult spinal deformity (ASD) have enhanced global deformity and lower-limb compensation associations. The advent of age-adjusted goals for classic ASD parameters (sagittal vertical axis, pelvic tilt, spino-pelvic mismatch [PI-LL]) has enabled individualized evaluation of successful versus failed realignment, though these remain to be radiographically assessed postoperatively. This study analyzes pre- and postoperative sagittal alignment to quantify patient-specific correction against age-adjusted goals, and presents differences in compensation in patients whose postoperative profile deviates from targets. Methods/UNASSIGNED:tests. Results/UNASSIGNED: < .001). Conclusions/UNASSIGNED:Global alignment cohort improvements were observed, and when comparing actual to age-adjusted alignment, undercorrections recruited pelvic and lower-limb flexion to compensate. Level of Evidence/UNASSIGNED:3.

OBJECTIVEThe surgical correction of adult spinal deformity (ASD) often involves modifying lumbar lordosis (LL) to restore ideal sagittal alignment. However, corrections that include large changes in LL increase the risk for development of proximal junctional kyphosis (PJK). Little is known about the impact of cranial versus caudal correction in the lumbar spine on the occurrence of PJK. The goal of this study was to investigate the impact of the location of the correction on acute PJK development.METHODSThis study was a retrospective review of a prospective multicenter database. Surgically treated ASD patients with early follow-up evaluations (6 weeks) and fusions of the full lumbosacral spine were included. Radiographic parameters analyzed included the classic spinopelvic parameters (pelvic incidence [PI], pelvic tilt [PT], PI-LL, and sagittal vertical axis [SVA]) and segmental correction. Using Glattes' criteria, patients were stratified into PJK and noPJK groups and propensity matched by age and regional lumbar correction (ΔPI-LL). Radiographic parameters and segmental correction were compared between PJK and noPJK patients using independent t-tests.RESULTSAfter propensity matching, 312 of 483 patients were included in the analysis (mean age 64 years, 76% women, 40% with PJK). There were no significant differences between PJK and noPJK patients at baseline or postoperatively, or between changes in alignment, with the exception of thoracic kyphosis (TK) and ΔTK. PJK patients had a decrease in segmental lordosis at L4-L5-S1 (-0.6° vs 1.6°, p = 0.025), and larger increases in segmental correction at cranial levels L1-L2-L3 (9.9° vs 7.1°), T12-L1-L2 (7.3° vs 5.4°), and T11-T12-L1 (2.9° vs 0.7°) (all p < 0.05).CONCLUSIONSAlthough achievement of an optimal sagittal alignment is the goal of realignment surgery, dramatic lumbar corrections appear to increase the risk of PJK. This study was the first to demonstrate that patients who developed PJK underwent kyphotic changes in the L4-S1 segments while restoring LL at more cranial levels (T12-L3). These findings suggest that restoring lordosis at lower lumbar levels may result in a decreased risk of developing PJK.

STUDY DESIGN/METHODS:Retrospective review of prospectively-collected database. OBJECTIVE:This study aims to compare 2-year clinical outcomes of patients who underwent surgical reconstructions based on their achievement to age-adjusted alignment ideals. SUMMARY OF BACKGROUND DATA/BACKGROUND:Recent research in sagittal plane has proposed age-adjusted alignment thresholds. However, the impact of these thresholds on postoperative health-related quality of life (HRQOL) is yet to be investigated. METHODS:Patients were included if they were more than 18-years old and underwent surgical correction of adult spinal deformity with a complete 2-year follow-up. Patients were stratified into three groups based on achievement of age-adjusted thresholds in pelvic tilt (PT), pelvic incidence minus lumbar lordosis (PI-LL), and sagittal vertical axis (SVA). First group included patients who reached the exact age-adjusted threshold ± 10 years (MATCHED), other two groups included patients who were over corrected (OVER), and under corrected (UNDER). Clinical outcomes including actual value and offset from age-adjusted Oswestry Disability Index, Short-Form-36 (SF-36) -physical component summary, and Scoliosis Research Society-22r (SRS-22r) were compared between groups at 2 years follow-up. RESULTS:A total of 343 patients (mean, 57 yrs and 83% females) were included. Sagittal profile of the population was: PT = 23.6°, SVA = 65.8 mm, and PI-LL = 15.6°. At 2-year follow-up, there was significant improvement in all sagittal modifiers with 25.7%, 24.3%, and 33.1% of the patients matching their age alignment targets in terms of PT, PI-LL, and SVA, respectively. For PT and PI-LL, the three groups (MATCHED, OVER, and UNDER) had comparable values and offsets from age-adjusted patient reported outcome. However, for SVA groups, patients in UNDER had significantly worse HRQOL than the two other groups. Patients in PT, PI-LL, and SVA UNDER groups were significantly younger than the other groups, P < 0.05. CONCLUSION/CONCLUSIONS:At 2 years after adult spinal deformity surgical treatment, only 24.3% to 33.1% of the patients reached age-adjusted alignment thresholds. Those under corrected in SVA demonstrated worse clinical outcomes. No significant improvements were found between matched and overcorrected patients, with overcorrection being an established risk for proximal junctional kyphosis. These results further emphasize the need for patient specific operative planning. LEVEL OF EVIDENCE/METHODS:3.

PURPOSE: A comprehensive understanding of normative sagittal profile is necessary for adult spinal deformity. Roussouly described four sagittal alignment types based on sacral slope, lumbar lordosis, and location of lumbar apex. However, the lower limb, a newly described component of spinal malalignment compensation, is missing from this classification. This study aims to propose a full-body sagittal profile classification in an asymptomatic population based on full-body imaging. METHODS: This is a retrospective analysis of a prospective single-center study of 116 asymptomatic volunteers. Cluster analysis including all sagittal parameters was first performed, and then ANOVA was performed between sub-clusters to eliminate the non-significantly different parameters. This loop was repeated until all parameters were significantly different between each sub-cluster. RESULTS: Three types of full-body sagittal profiles were finalized according to cluster analysis with ten radiographic parameters: hyperlordosis type (77 subjects), neutral type (28 subjects), and compensated type (11 subjects). Radiographic parameters included knee angle, pelvic shift, pelvic angle, PT, PI-LL, C7-S1 SVA, TPA, T1 slope, C2-C7 angle, and C2-C7 SVA. Age was significantly different across compensation types, while BMI and gender were comparable. Age-matched subjects were randomly selected with 11 subjects in each type. ANOVA analysis revealed that all parameters but PT and C2-C7 angle remained significantly different. CONCLUSIONS: The current three compensation types of full-body sagittal profiles in asymptomatic adults included significant changes from cervical region to knee, indicating that subjects should be evaluated with full-length imaging. All three types exist regardless of age, but the distribution may vary.

PURPOSE: While there is a consensus that pelvic incidence (PI) remains constant after skeletal maturity, recent reports argue that PI increases after 60 years. This study aims to investigate whether PI increases with age and to determine potential associated factors. METHODS: 1510 patients with various spinal degenerative and deformity pathologies were enrolled, along with an additional 115 asymptomatic volunteers. Subjects were divided into six age subgroups with 10-year intervals. RESULTS: PI averaged 54.1 degrees in all patients. PI was significantly higher in the 45-54-year age group than 35-44-year age group (55.8 degrees vs. 49.7 degrees ). There were significant PI differences between genders after age 45. Linear regression revealed age, gender and malalignment as associated factors for increased PI with R 2 of 0.22 (p < 0.001). CONCLUSIONS: PI is higher in female patients and in older patients, especially those over 45 years old. Spinal malalignment also may have a role in increased PI due to increased L5-S1 bending moment.

MINI: Despite differences in sagittal malalignment, antero-posterior pelvic translation maintained the position of T9 in line with the ankles, independently of sagittal vertical axis. Pelvic tilt was directly predicted by lower limb compensatory mechanisms. Therefore, these adaptation mechanisms being included in pelvic tilt analysis, it does not need additional consideration in the surgical planning. STUDY DESIGN: Retrospective review. OBJECTIVE: To investigate the role of lower limbs compensation with progressive sagittal malalignment. SUMMARY OF BACKGROUND DATA: Although lower limb compensatory mechanisms are established response to progressive sagittal malalignment, their specific role and potential impact on surgical planning has not been evaluated. METHODS: Single center retrospective review of full body x-rays was performed in patients of age >20 years. Parameters were measured with dedicated software. Population was stratified by 50 mm intervals of sagittal vertical axis (SVA) and one-way ANOVA was performed to compare P.shift (P.shift = anteroposterior translation of the pelvis vs. the feet) across SVA groups. Anteroposterior offset of each vertebra in relation to a vertical line extended from the distal tibial metaphysis (TM) was investigated. Linear regression was performed to predict pelvic tilt (PT) using Knee angle (KA) and P.shift, whereas controlling for pelvic incidence minus lumbar lordosis mismatch (PI-LL) and SVA. RESULTS: A total of 2124 patient visits were included (PI = 55.1 +/- 14.1 degrees , PT=21.0 +/- 11 degrees , PI-LL=6.3 +/- 17.3 degrees , SVA = 29 +/- 51 mm). With progressively increased SVA, P.shift decreased from 30 to -100 mm (all P < 0.005). Analysis of vertebral offset from the distal tibial metaphysis revealed that T9 was aligned with the TM line across all SVA groups. Prediction of PT based on PI-LL and SVA yielded R=0.76 (P < 0.001). Subsequent addition of KA and P.shift as independent parameters using hierarchical multiple regression led to significant improvement in R, demonstrating the independent role of lower limbs parameters in PT prediction. KA and P.shift had a positive standardized coefficient (all P < 0.05). CONCLUSION: Lower limb compensatory mechanisms increase with progressive sagittal malalignment. Anteroposterior translation of pelvis allows the T9 vertebra to remain in line with the ankle ("conus of economy"). Lower limb compensatory mechanisms are positive predictors of PT and thus do not require additional consideration in surgical realignment planning. LEVEL OF EVIDENCE: 3.

OBJECTIVE Three-column osteotomy (3CO) is a demanding technique that is performed to correct sagittal spinal malalignment. However, the impact of the 3CO level on pelvic or truncal sagittal correction remains unclear. In this study, the authors assessed the impact of 3CO level and postoperative apex of lumbar lordosis on sagittal alignment correction, complications, and revisions. METHODS In this retrospective study of a multicenter spinal deformity database, radiographic data were analyzed at baseline and at 1- and 2-year follow-up to quantify spinopelvic alignment, apex of lordosis, and resection angle. The impact of 3CO level and apex level of lumbar lordosis on the sagittal correction was assessed. Logistic regression analyses were performed, controlling for cofounders, to investigate the effects of 3CO level and apex level on intraoperative and postoperative complications as well as on the need for subsequent revision surgery. RESULTS A total of 468 patients were included (mean age 60.8 years, mean body mass index 28.1 kg/m2); 70% of patients were female. The average 3CO resection angle was 25.1 degrees and did not significantly differ with regard to 3CO level. There were no significant correlations between the 3CO level and amount of sagittal vertical axis or pelvic tilt correction. The postoperative apex level significantly correlated with greater correction of pelvic tilt (2 degrees per more caudal level, R = -0.2, p = 0.006). Lower-level 3CO significantly correlated with revisions for pseudarthrosis (OR = 3.88, p = 0.001) and postoperative motor deficits (OR = 2.02, p = 0.026). CONCLUSIONS In this study, a more caudal lumbar 3CO level did not lead to greater sagittal vertical axis correction. The postoperative apex of lumbar lordosis significantly impacted pelvic tilt. 3CO levels that were more caudal were associated with more postoperative motor deficits and revisions.