STUDY DESIGN.Retrospective clinical and radiographic single-center study
OBJECTIVE.Assess simultaneous cervical spine and lower extremity compensatory changes with changes in thoracolumbar spinal ...alignment.
SUMMARY OF BACKGROUND DATA.Full-body stereoradiographic imaging allows better understanding of reciprocal changes in cervical and lower extremity alignment in the setting of thoracolumbar malalignment. Few studies describe the simultaneous effect of alignment correction on these mechanisms.
METHODS.Patients ≥18 years undergoing instrumented thoracolumbar fusion without previous cervical spine fusion, hip, knee or ankle arthroplasty were included. Spinopelvic, lower extremity and cervical alignment were assessed from full-body standing stereoradiographs using validated software. Patients were matched for pelvic incidence and stratified based on baseline T1-pelvic angle (TPA) asTPA-Low <14°, TPA-Moderate =14–22° and TPA-High >22°. Perioperative changes between baseline and first postoperative visit <6 months in lower extremity alignment (pelvic shiftP Shift, sacrofemoral angleSFA, Knee AngleKA, Ankle AngleAA, global sagittal axisGSA) and cervical alignment (C0-C2 angle, C2-slope, C2-C7 lordosis and C2-C7 SVA:cSVA) were correlated with change in magnitude of TPA and sagittal vertical axis (SVA) correction.
RESULTS.After matching, 87 patients were assessed. Increasing baseline TPA severity associated with a progressive increase in all regional spinopelvic parameters except thoracic kyphosis, in addition to increased SFA, P Shift, KA, GSA, and C2-C7 lordosis. As TPA correction increased, there was a reciprocal reduction in SFA, KA, P Shift, GSA and C2-C7 lordosis. Change in SVA correlated most with change in GSA (r = 0.886), P Shift (r = 0.601), KA (r = 0.534) and C2-C7 lordosis (r = 0.467). Change in TPA correlated with change in SFA (r = 0.372) while SVA did not.
CONCLUSIONS.Patients with thoracolumbar malalignment exhibit compensatory changes in cervical spine and lower extremity simultaneously in the form of cervical hyperlordosis, pelvic shift, knee flexion, and pelvic retroversion. These compensatory mechanisms resolve reciprocally in a linear fashion following optimal surgical correction.
LEVEL OF EVIDENCE.3
STUDY DESIGN.Post hoc analysis of prospectively collected data.
OBJECTIVE.Development of methods to determine in vivo spinal cord dimensions and application to correlate preoperative alignment, ...myelopathy, and health-related quality-of-life scores in patients with cervical spondylotic myelopathy (CSM).
SUMMARY OF BACKGROUND DATA.CSM is the leading cause of spinal cord dysfunction. The association between cervical alignment, sagittal balance, and myelopathy has not been well characterized.
METHODS.This was a post hoc analysis of the prospective, multicenter AOSpine North America CSM study. Inclusion criteria for this study required preoperative cervical magnetic resonance imaging (MRI) and neutral sagittal cervical radiography. Techniques for MRI assessment of spinal cord dimensions were developed. Correlations between imaging and health-related quality-of-life scores were assessed.
RESULTS.Fifty-six patients met inclusion criteria (mean age = 55.4 yr). The modified Japanese Orthopedic Association (mJOA) scores correlated with C2–C7 sagittal vertical axis (SVA) (r = −0.282, P = 0.035). Spinal cord volume correlated with cord length (r = 0.472, P < 0.001) and cord average cross-sectional area (r = 0.957, P < 0.001). For all patients, no correlations were found between MRI measurements of spinal cord length, volume, mean cross-sectional area or surface area, and outcomes. For patients with cervical lordosis, mJOA scores correlated positively with cord volume (r = 0.366, P = 0.022), external cord area (r = 0.399, P = 0.012), and mean cross-sectional cord area (r = 0.345, P = 0.031). In contrast, for patients with cervical kyphosis, mJOA scores correlated negatively with cord volume (r = −0.496, P = 0.043) and mean cross-sectional cord area (r = −0.535, P = 0.027).
CONCLUSION.This study is the first to correlate cervical sagittal balance (C2–C7 SVA) to myelopathy severity. We found a moderate negative correlation in kyphotic patients of cord volume and cross-sectional area to mJOA scores. The opposite (positive correlation) was found for lordotic patients, suggesting a relationship of cord volume to myelopathy that differs on the basis of sagittal alignment. It is interesting to note that sagittal balance but not kyphosis is tied to myelopathy score. Future work will correlate alignment changes to cord morphology changes and myelopathy outcomes.Summary Statements. This is the first study to correlate sagittal balance (C2–C7 SVA) to myelopathy severity. We found a moderate negative correlation in kyphotic patients of cord volume and cross-sectional area to mJOA scores. The opposite (positive correlation) was found for lordotic patients, suggesting a relationship of cord volume to myelopathy that differs on the basis of sagittal alignment.
STUDY DESIGN.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.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 wasPT = 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.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 Evidence3
BACKGROUND:The maintenance of horizontal gaze is an essential function of upright posture and global sagittal spinal alignment. Horizontal gaze is classically measured by the chin-brow vertical angle ...(CBVA), which is not readily measured on most lateral spine radiographs.
OBJECTIVE:To evaluate relations between CBVA and the slope of the line of sight, the slope of McGregorʼs line (McGS), and Oswestry Disability Index.
METHODS:Patients were identified from a single center database of 531 spine patients who underwent full-body EOS x-rays. Correlations between CBVA, the slope of the line of sight, and McGS were assessed. Using a quadratic regression with Oswestry Disability Index and CBVA, windows of low disability were identified. Comparison of sagittal spinopelvic parameters was carried out between patients with “ascending gaze” and “neutral position.”
RESULTS:Three hundred three patients were included (74% female, mean age 54.8 years, body mass index 26.6 ± 6.0 kg/m). CBVA strongly correlated with the slope of the line of sight (r = 0.996) and McGS (r = 0.862). Regression studies between Oswestry Disability Index and CBVA yielded a range of values corresponding to low disability (−4.7 degrees to 17.7 degrees). Similarly, a low disability range for the slope of the line of sight (−5.1 degrees to 18.5 degrees) and McGS (−5.7 degrees to 14.3 degrees) was computed. Patients with “ascending gaze” had a worse spinopelvic alignment than “neutral position” patients.
CONCLUSION:The slope of the line of sight and McGS correlated strongly with CBVA and can be used as surrogate measures. The range of values for these measures corresponding to low disability was identified. These values can be used as a general guideline to assess alignment for diagnostic purposes. Cervical compensatory mechanism may modify the natural head position in sagittally misaligned patients.
ABBREVIATIONS:CBVA, chin-brow vertical angleHRQoL, health-related quality of lifeMcGS, slope of McGregorʼs lineODI, Oswestry Disability IndexSLs, slope of the line of sight
Cadaveric.
The aim of this study was to quantify the amplitude and duration of surgeons' muscle exertion from pedicle cannulation to screw placement using both manual and power-assisted tools in a ...simulated surgical environment using surface electromyography (EMG).
A survey of Scoliosis Research Society members reported rates of neck pain, rotator cuff disease, lateral epicondylitis, and cervical radiculopathy at 3 ×, 5 ×, 10 ×, and 100 × greater than the general population. The use of power-assisted tools in spine surgery to facilitate pedicle cannulation through screw placement during open posterior fixation surgery may reduce torque on the upper limb and risk of overuse injury.
Pedicle preparation and screw placement was performed from T4-L5 in four cadavers by two board-certified spine surgeons using both manual and power-assisted techniques. EMG recorded muscle activity from the flexor carpi radialis, extensor carpi radialis, biceps, triceps, deltoid, upper trapezius, and neck extensors. Muscle activity was reported as a percentage of the maximum voluntary exertion of each muscle group (%MVE) and muscle exertion was linked to low- (0-20% MVE), moderate- (20%-45% MVE), high- (45%-70% MVE) and highest- (70%-100% MVE) risk of overuse injury based on literature.
Use of power-assisted tools for pedicle cannulation through screw placement maintains average muscle exertion at low risk for overuse injury for every muscle group. Conversely with manual technique, the extensor carpi radialis, biceps, upper trapezius and neck extensors operate at levels of exertion that risk overuse injury for 50% to 92% of procedure time. Powerassisted tools reduce average muscle exertion of the biceps, triceps, and deltoid by upwards of 80%.
Power-assisted technique protects against risk of overuse injury. Elevated muscle exertion of the extensor carpi radialis, biceps, upper trapezius, and neck extensors during manual technique directly correlate with surgeons' self-reported diagnoses of lateral epicondylitis, rotator cuff disease, and cervical myelopathy.Level of Evidence: N/A.
The detection of low levels of pharmaceuticals in rivers and streams, drinking water, and groundwater has raised questions as to whether these levels may affect human health. This report presents ...human health risk assessments for 26 active pharmaceutical ingredients (APIs) and/or their metabolites, representing 14 different drug classes, for which environmental monitoring data are available for the United States. Acceptable daily intakes (ADIs) are derived using the considerable data that are available for APIs. The resulting ADIs are designed to protect potentially exposed populations, including sensitive sub-populations. The ADIs are then used to estimate predicted no effect concentrations (PNECs) for two sources of potential human exposure: drinking water and fish ingestion. The PNECs are compared to measured environmental concentrations (MECs) from the published literature and to maximum predicted environmental concentrations (PECs) generated using the P
hATE model. The P
hATE model predictions are made under conservative assumptions of low river flow and no depletion (i.e., no metabolism, no removal during wastewater or drinking water treatment, and no instream depletion). Ratios of MECs to PNECs are typically very low and consistent with PEC to PNEC ratios. For all 26 compounds, these low ratios indicate that no appreciable human health risk exists from the presence of trace concentrations of these APIs in surface water and drinking water.
Descriptive study of the Scoliosis Research Society (SRS) Classification for Adult Spinal Deformity using interobserver reliability measures for validation of the system.
To propose and validate a ...classification system for adult spinal deformity that will have utility in reporting on treatment options and outcomes for affected adults.
Classification systems exist for adolescent idiopathic scoliosis and have utility in categorizing spinal deformity and guiding choices for management. Adult spinal deformity is distinct from adolescent deformity. Important distinctions include present impairment and pain, regional and global decompensation, and degenerative changes within the deformity. A useful classification system for adult spinal deformity does not exist. The absence of a classification system for adult deformity compromises the ability to report on similar cases and to develop an evidence-based approach to care.
Descriptive study design with development of an SRS Classification System using the Delphi Method. Validation of the system using interobserver reliability measures based on responses of SRS-member surgeons to radiographic case presentations.
Nineteen surgeons evaluated 25 cases of adult spinal deformity. Interobserver reliability for curve types (kappa = 0.64), regional sagittal modifiers (kappa = 0.73), and degenerative lumbar modifiers (kappa = 0.65) were substantial. Interobserver reliability was moderate (kappa = 0.56) for choosing a cephalad level for operative treatment and substantial for choosing a caudad level (kappa = 0.77).
A uniform system for classification of adult spinal deformity has significant utility in improving the ability of surgeons and authors to compare and combine similar cases, and in improving the accuracy of reports on the outcomes of care for adults with spinal deformity. The SRS Classification System for Adult Spinal Deformity has good interobserver reliability and is predictive of surgical strategies. Further validation of the SRS Classification System will include measures of intraobserver reliability, and inclusion of clinical characteristics of patient presentation and comorbidities.
STUDY DESIGN.Retrospective review of prospective multicenter database.
OBJECTIVE.To identify an optimal set of factors predicting the risk of proximal junctional failure (PJF) while taking the time ...dependency of PJF and those factors into account.
SUMMARY OF BACKGROUND DATA.Surgical correction of adult spinal deformity (ASD) can be complex and therefore, may come with high revision rates due to PJF.
METHODS.Seven hundred sixty-three operative ASD patients with a minimum of 1-year follow-up were included. PJF was defined as any type of proximal junctional kyphosis (PJK) requiring revision surgery. Time-dependent ROC curves were estimated with corresponding Cox proportional hazard models. The predictive abilities of demographic, surgical, radiographic parameters, and their possible combinations were assessed sequentially. The area under the curve (AUC) was used to evaluate models’ performance.
RESULTS.PJF occurred in 42 patients (6%), with a median time to revision of approximately 1 year. Larger preoperative pelvic tilt (PT) (hazard ratio HR=1.044, P = 0.034) significantly increased the risk of PJF. With respect to changes in the radiographic parameters at 6-week postsurgery, larger differences in pelvic incidence-lumbar lordosis (PI-LL) mismatch (HR = 0.924, P = 0.002) decreased risk of PJF. The combination of demographic, surgical, and radiographic parameters has the best predictive ability for the occurrence of PJF (AUC = 0.863), followed by demographic along with radiographic parameters (AUC = 0.859). Both models’ predictive ability was preserved over time.
CONCLUSIONS.Over correction increased the risk of PJF. Radiographic along with demographic parameters have shown the approximately equivalent predictive ability for PJF over time as with the addition of surgical parameters. Radiographic rather than surgical factors may be of particular importance in predicting the development of PJF over time. These results set the groundwork for risk stratification and corresponding prophylactic interventions for patients undergoing ASD surgery.Level of Evidence4
With advances in the understanding of adult spinal deformity (ASD), more complex osteotomy and fusion techniques are being implemented with increasing frequency. Patients undergoing ASD corrections ...infrequently require extended acute care, longer inpatient stays, and are discharged to supervised care. Given the necessity of value-based health care, identification of clinical indicators of adverse discharge disposition in ASD surgeries is paramount.
Using the nationwide and surgeon-created databases, the present study aimed to identify predictors of adverse discharge disposition after ASD surgeries and view the corresponding differences in charges.
This is a retrospective analysis of patients on the National Surgical Quality Improvement Program (NSQIP) database and of cost data from Medicare PearlDiver Database.
Patients undergoing thoracolumbar surgery for correction of ASD were included in the study.
Primary analysis was performed to compare patients discharged to home with patients who either expired or were discharged to locations other than home. Secondary analysis was performed to determine the cost differences across discharge groups.
Patients on NSQIP undergoing thoracolumbar ASD-corrective surgery with a primary diagnosis of scoliosis (ICD-9 code 737.x) and over the age of 18 were isolated. Predictors (demographic, clinical, and complications) of not-home (NH; rehab or skilled nursing facility) discharge were analyzed using binary logistic regression controlling for levels fused, decompressions, osteotomies, and revisions. Average 30- and 90-day costs of care were reported in home, rehab, and skilled nursing facility discharge groups in patients undergoing 8+ level thoracolumbar fusion.
A total of 1,978 patients undergoing lumbar ASD-corrective surgery were included for analysis (average age: 59.3 years, sex: 64% female). Average length of stay was 6.58 days. On multivariate regression analysis, age over 60 years (odds ratio OR: 0.28, confidence interval CI: 0.22–0.34) and female sex (p=.003) were independent predictors of adverse discharge status. Partially dependent preoperational functional status, defined as reliance on another person to complete some activities of daily living, increased likelihood of adverse discharge disposition (OR: 0.57, CI: 0.35–0.90). Despite controlling for all clinical variables except for the ones specific to each analysis, Smith-Petersen osteotomy (OR: 0.51, CI: 0.40–0.64), interbody device placement (OR: 0.80, CI: 0.64–0.98), and fixation to the iliac (OR: 0.54, CI: 0.41–0.70) increased the likelihood of adverse discharge. Complications most associated with adverse discharge were urinary tract infections (OR: 0.34, CI: 0.21–0.57) and blood transfusions (OR: 0.42, CI: 0.34–0.52). Relative to home discharge, 30-day costs of care were +$21,061 more expensive in rehab discharges, but not different in skilled nursing facility discharges (+$5,791, p=.177). The 90-day costs of care were $23,815 in rehab discharges (p<.001), but again not different from skilled nursing facility discharges (+$6,091, p=.212).
Discharge destination to rehabilitation has a significant impact on the cost of thoracolumbar ASD surgeries. Patient selection can predict patients at higher risk of discharges to rehab or skilled nursing facility.
STUDY DESIGN.Retrospective review of a prospectively collected database.
OBJECTIVE.To define a simplified singular measure of cervical deformity (CD), C2 slope (C2S), which correlates with ...postoperative outcomes.
SUMMARY OF BACKGROUND DATA.Sagittal malalignment of the cervical spine, defined by the cervical sagittal vertical axis (cSVA) has been associated with poor outcomes following surgical correction of the deformity. There has been a proliferation of parameters to describe CD. This added complexity can lead to confusion in classifying, treating, and assessing outcomes of CD surgery.
METHODS.A prospective database of CD patients was analyzed. Inclusion criteria were cervical kyphosis>10°, cervical scoliosis>10°, cSVA>4 cm, or chin-brow vertical angle >25°. Patients were categorized into two groups and compared based on whether the apex of the deformity was in the cervical (C) or the cervicothoracic (CT) region. Radiographic parameters were correlated to C2S, T1 slope (T1S) and 1-year health-related quality-of-life outcomes as measured by the EuroQol 5 Dimension questionnaire (EQ5D), modified Japanese Orthopedic Association Scale, numeric rating scale for neck pain, and the Neck Disability Index (NDI).
RESULTS.One hundred four CD patients (C = 74, CT = 30; mean age 61 yr, 56% women, 42% revisions) were included. CT patients had higher baseline cSVA and T1S (P < 0.05). C2S correlated with T1 slope minus cervical lordosis (TS-CL) (r = 0.98, P < 0.001) and C0-C2 angle, cSVA, CL, T1S (r = 0.37–0.65, P < 0.001). Correlation of cSVA with C0-C2 was weaker (r = 0.48, P < 0.001). At 1-year postoperatively, higher C2S correlated with worse EQ-5D (r = 0.28, P = 0.02); in CT patients, higher C2S correlated with worse NDI, modified Japanese Orthopedic Association Scale, numeric rating scale for neck pain, and EQ5D (all r > 0.5, P≤0.05). Using linear regression, moderate disability by EQ5D corresponded to C2S of 20°(r = 0.08). For CT patients, C2S = 17° corresponded to moderate disability by NDI (r = 0.4), and C2S = 20° by EQ5D (r = 0.25).
CONCLUSION.C2S correlated with upper-cervical and subaxial alignment. C2S correlated strongly with TS-CL (R = 0.98, P < 0.001) because C2S is a mathematical approximation of TS-CL. C2S is a useful marker of CD, linking the occipitocervical and cervico-thoracic spine. C2S defines the presence of a mismatch between cervical lordosis and thoracolumbar alignment. Worse 1-year postoperative C2 slope correlated with worse health outcomes.Level of Evidence3
