Faculty Bibliography

Background/UNASSIGNED:Cervical kyphosis and C2-C7 plumb line (CPL) are established descriptors of cervical sagittal deformity (CSD). Reciprocal changes in these parameters have been demonstrated in thoracolumbar deformity correction. The purpose of this study was to investigate the development of CSD, using T1 slope minus cervical lordosis (TS-CL) to define CSD and to correlate TS-CL and a novel global sagittal parameter, cervical-thoracic pelvic angle (CTPA), with CPL. Methods/UNASSIGNED:test. Logistic regression modeling was used to determine predictors of postoperative CSD. Results/UNASSIGNED:= .029). Conclusions/UNASSIGNED:TS-CL and CTPA correlated significantly with established sagittal balance measures. Whereas reciprocal change in cervical and thoracolumbar alignment was demonstrated in the compensated cohort, the uncompensated population had progression of their cervical deformities after three-column osteotomy. Clinical Relevance/UNASSIGNED:The balance between TS-CL mirrors the relationship between pelvic incidence minus lumbar lordosis in defining deformities of their respective spinal regions.

STUDY DESIGN/METHODS:Prospective multicenter analysis of adult spinal deformity (ASD) patients. OBJECTIVE:The aim of this study was to introduce the lumbar pelvic angle (LPA), a novel parameter of spinopelvic alignment. SUMMARY OF BACKGROUND DATA/BACKGROUND:The T1 pelvic angle (TPA), a measure of global spinopelvic alignment, correlates with health-related quality of life (HRQOL), but it may not be measureable on all intraoperative x-rays. In patients with previous interbody fusion at L5-S1, the plane of the S1 endplate can be blurred, creating error in pelvic incidence and lumbar lordosis (PI-LL) measure. The LPA is more readily measured on intraoperative imaging than the TPA. METHODS:ASD patients were included with either coronal Cobb angle >20°, sagittal vertical axis (SVA) >5 cm, thoracic kyphosis >60°, or pelvic tilt (PT) >25°. Measures of disability included Oswestry Disability Index (ODI), Scoliosis Research Society (SRS), and Short Form (SF)-36. Baseline and 2-year follow-up radiographic and HRQOL outcomes were evaluated. Linear regressions compared LPA with radiographic parameters and HRQOL. RESULTS:A total of 852 ASD patients (407 operative) were enrolled (mean age 53.7). Baseline LPA correlated with PI-LL (r = 0.79), PT (r = 0.78), TPA (r = 0.82), and SVA (r = 0.61) (all P < 0.001). PI-LL, LPA, and TPA correlated with ODI (r = 0.42/0.29/0.45), SF-36 physical component score (-0.43/-0.28/-0.45) SRS (-0.354/-0.23/-0.37) with all P < 0.001. At 2 years' follow-up, LPA correlated with PI-LL (r = 0.77), PT (r = 0.78), TPA (r = 0.83), and SVA (r = 0.57) (all P < 0.001). Categorizing patients by increasing LPA (<7°; 7°-15°; >15°) revealed progressive increases in all HRQOL, PI-LL (-3.2°/12.7°/32.4°), and TPA (9.7°/20.1°/34.6°) with all P < 0.001. Moderate disability (ODI = 40) corresponded to LPA 10.1°, PI-LL 12.6°, and TPA 20.6°. Mild disability (ODI = 20) corresponded to LPA 7.2°, PI-LL 4.2°, and TPA 14.7°. CONCLUSION/CONCLUSIONS:LPA correlates with TPA, PI-LL, and HRQOL in ASD patients. LPA can be used as an intraoperative tool to gauge correction with a target LPA of <7.2°. LPA predicts global alignment, as it correlates with baseline and 2-year TPA and SVA. Along with the cervical-thoracic pelvic angle and TPA, LPA completes the fan of spinopelvic alignment. LEVEL OF EVIDENCE/METHODS:3.

OBJECTIVE:The primary driver (PD) of cervical malalignment is important in characterizing cervical deformity (CD) and should be included in fusion to achieve alignment and quality-of-life goals. This study aims to define how PDs improve understanding of the mechanisms of CD and assesses the impact of driver region on realignment/outcomes. METHODS:Inclusion: radiographic CD, age >18 years, 1 year follow-up. PD apex was classified by spinal region: cervical, cervicothoracic junction (CTJ), thoracic, or spinopelvic by a panel of spine deformity surgeons. Primary analysis evaluated PD groups meeting alignment goals (by Ames modifiers cervical sagittal vertical axis/T1 slope minus cervical lordosis/chin-brow vergical angle/modified Japanese Orthopaedics Association questionnaire) and health-related quality of life (HRQL) goals (EuroQol-5 Dimensions questionnaire/Neck Disability Index/modified Japanese Orthopaedics Association questionnaire) using t tests. Secondary analysis grouped interventions by fusion constructs including the primary or secondary apex based on lowest instrumented vertebra: cervical, lowest instrumented vertebra (LIV) ≤C7; CTJ, LIV ≤T3; and thoracic, LIV ≤T12. RESULTS:A total of 73 patients (mean age, 61.8 years; 59% female) were evaluated with the following PDs of their sagittal cervical deformity: cervical, 49.3%; CTJ, 31.5%; thoracic, 13.7%; and spinopelvic, 2.7%. Cervical drivers (n = 36) showed the greatest 1-year postoperative cervical and global alignment changes (improvement in T1S, CL, C0-C2, C1 slope). Thoracic drivers were more likely to have persistent severe T1 slope minus cervical lordosis modifier grade at 1 year (0, 20.0%; +, 0.0%; ++, 80.0%). Cervical deformity modifiers tended to improve in cervical patients whose construct included the PD apex (included, 26%; not, 0%; P = 0.068). Thoracic and cervicothoracic PD apex patients did not improve in HRQL goals when PD apex was not treated. CONCLUSIONS:CD structural drivers have an important effect on treatment and 1-year postoperative outcomes. Cervical or thoracic drivers not included in the construct result in residual deformity and inferior HRQL goals. These factors should be considered when discussing treatment plans for patients with CD.

STUDY DESIGN/METHODS:Consensus-building using the Delphi and nominal group technique. OBJECTIVE:To establish best practice guidelines using formal techniques of consensus building among a group of experienced spinal deformity surgeons to avert wrong-level spinal deformity surgery. SUMMARY OF BACKGROUND DATA/BACKGROUND:Numerous previous studies have demonstrated that wrong-level spinal deformity occurs at a substantial rate, with more than half of all spine surgeons reporting direct or indirect experience operating on the wrong levels. Nevertheless, currently, guidelines to avert wrong-level spinal deformity surgery have not been developed. METHODS:The Delphi process and nominal group technique were used to formally derive consensus among 16 fellowship-trained spine surgeons. Surgeons were surveyed for current practices, presented with the results of a systematic review, and asked to vote anonymously for or against item inclusion during three iterative rounds. Agreement of 80% or higher was considered consensus. Items near consensus (70% to 80% agreement) were probed in detail using the nominal group technique in a facilitated group meeting. RESULTS:Participants had a mean of 13.4 years of practice (range: 2-32 years) and 103.1 (range: 50-250) annual spinal deformity surgeries, with a combined total of 24,200 procedures. Consensus was reached for the creation of best practice guidelines (BPGs) consisting of 17 interventions to avert wrong-level surgery. A final checklist consisting of preoperative and intraoperative methods, including standardized vertebral-level counting and optimal imaging criteria, was supported by 100% of participants. CONCLUSION/CONCLUSIONS:We developed consensus-based best practice guidelines for the prevention of wrong-vertebral-level surgery. This can serve as a tool to reduce the variability in preoperative and intraoperative practices and guide research regarding the effectiveness of such interventions on the incidence of wrong-level surgery. LEVEL OF EVIDENCE/METHODS:Level V.

The sagittal plane is known to be important in correction of adult spinal deformity. When surgery is indicated, the surgeon is provided with several tools and techniques to restore balance. But proper use of these tools is essential to avoid harmful complications. This article examines these tools with a focus on lumbar lordosis and the lumbopelvic junction. Positioning, releases, osteotomies, and instrumentation are considered with special attention to the alignment measurements they affect.

BACKGROUND: Adult cervical deformity (ACD) classifications have not been implemented in a prospective ACD population and in conjunction with adult spinal deformity (ASD) classifications. OBJECTIVE: To characterize cervical deformity type and malalignment with 2 classifications (Ames-ACD and Schwab-ASD). METHODS: Retrospective review of a prospective multicenter ACD database. Inclusion: patients >/=18 yr with pre- and postoperative radiographs. Patients were classified with Ames-ACD and Schwab-ASD schemes. Ames-ACD descriptors (C = cervical, CT = cervicothoracic, T = thoracic, S = coronal, CVJ = craniovertebral) and alignment modifiers (cervical sagittal vertical axis [cSVA], T1 slope minus cervical lordosis [TS-CL], modified Japanese Ortphopaedic Association [mJOA] score, horizontal gaze) were assigned. Schwab-ASD curve type stratification and modifier grades were also designated. Deformity and alignment group distributions were compared with Pearson chi 2 /ANOVA. RESULTS: Ames-ACD descriptors in 84 patients: C = 49 (58.3%), CT = 20 (23.8%), T = 9 (10.7%), S = 6 (7.1%). cSVA modifier grades differed in C, CT, and T deformities ( P < .019). In C, TS-CL grade prevalence differed ( P = .031). Among Ames-ACD modifiers, high (1+2) cSVA grades differed across deformities (C = 47.7%, CT = 89.5%, T = 77.8%, S = 50.0%, P = .013). Schwab-ASD curve type and presence (n = 74, T = 2, L = 6, D = 2) differed significantly in S deformities ( P < .001). Higher Schwab-ASD pelvic incidence minus lumbar lordosis grades were less likely in Ames-ACD CT deformities ( P = .027). Higher pelvic tilt grades were greater in high (1+2) cSVA (71.4% vs 36.0%, P = .015) and high (2+3) mJOA (24.0% vs 38.1%, P = .021) scores. Postoperatively, C and CT deformities had a trend toward lower cSVA grades, but only C deformities differed in TS-CL grade prevalence (0 = 31.3%, 1 = 12.2%, 2 = 56.1%, P = .007). CONCLUSION: Cervical deformities displayed higher TS-CL grades and different cSVA grade distributions. Preoperative associations with global alignment modifiers and Ames-ACD descriptors were observed, though only cervical modifiers showed postoperative differences.

BACKGROUND: Global sagittal deformity is an established cause of disability. However, measurements of sagittal alignment are often ignored when patients present with symptoms localizing to the cervical or lumbar spine. OBJECTIVE: To develop scoring scales to predict the risk of sagittal malalignment in patients with only cervical or lumbar spine radiographs. METHODS: A retrospective review of a prospectively maintained multicenter adult spinal deformity database was performed. Primary outcome (sagittal malalignment) was defined as a C7 plumbline >/= 50 mm. Two multivariate logistic regressions were performed using patient characteristics and measurements derived from cervical or lumbar radiographs as covariates. Point scores were assigned to age, body mass index (BMI), and lumbar lordosis or T1 slope by rounding their ss coefficients to the nearest integer. RESULTS: Nine hundred seventy-nine patients were included, with 652 randomly assigned to the derivation cohort (used to build the score) and 327 comprising the validation set. Final cervical score for the primary outcome included BMI >/= 25 (1 point), age >/= 55 yr (2 points), and T1 slope >/= 27 o (2 points). Final lumbar score for the primary outcome included BMI >/= 25 (1 point), age >/= 55 yr (1 point), and lumbar lordosis >/= 45 o (-1 points). High scores for both the cervical and lumbar spine presented with high specificity and positive likelihood ratios of sagittal malalignment. CONCLUSION: We developed scoring scales to predict global sagittal malalignment utilizing clinical covariates and cervical or lumbar radiographs. Patients with high scores may prompt imaging with long-cassette plain films to evaluate for global sagittal imbalance.

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.

PURPOSE: Reciprocal mechanisms for standing alignment have been described in thoraco-lumbar deformity but have not been studied in patients with primary cervical deformity (CD). The purpose of this study is to report upper- and infra-cervical sagittal compensatory mechanisms in patients with CD and evaluate their changes post-operatively. METHODS: Global spinal alignment was studied in a prospective database of operative CD patients. Inclusion criteria were any of the following: cervical kyphosis (CK) > 10 degrees , cervical scoliosis > 10 degrees , cSVA (C2-C7 Sagittal vertical axis) > 4 cm or CBVA (Chin Brow Vertical Angle) > 25 degrees . For this study, patients who had previous fusion outside C2 to T4 segments were excluded. Patients were sub-classified by increasing severity of cervical kyphosis [CL (cervical lordosis): < 0 degrees , CK-low 0 degrees -10 degrees , CK-high > 10 degrees ] and cSVA (cSVA-low 0-4 cm, cSVA-mid 4-6 cm, cSVA-high > 6 cm) and were compared for pre- and 3-month post-operative regional and global sagittal alignment to determine compensatory recruitment. RESULTS: 75 CD patients (mean age 61.3 years, 56% women) were included. Patients with progressively larger CK had a progressive increase in C0-C2 (CL = 34 degrees , CK-low = 37 degrees , CK-high = 44 degrees , p = 0.004), C2Slope and T1Slope-CL (p < 0.05). As the cSVA increased, there was progressive increase in C2Slope, T1Slope and TS-CL (p < 0.05) and patients compensated through increasing C0-C2 (cSVA-low = 33 degrees , cSVA-mid = 40 degrees , cSVA-high = 43 degrees , p = 0.007) and pelvic tilt (cSVA-low = 14.9 degrees , cSVA-mid = 24.1 degrees , cSVA-high = 24.9 degrees , p = 0.02). At 3 months post-op, with significant improvement in cervical alignment, there was relaxation of C0-C2 (39 degrees -35 degrees , p = 0.01) which positively correlated with magnitude of deformity correction. CONCLUSIONS: Patients with cervical malalignment compensate with upper cervical hyper-lordosis, presumably for the maintenance of horizontal gaze. As cSVA increases, patients also tend to exhibit increased pelvic retroversion. Following surgical treatment, there was relaxation of upper cervical compensation.

Study Design/UNASSIGNED:Retrospective radiological review. Purpose/UNASSIGNED:To quantify the effect of sitting vs supine lumbar spine magnetic resonance imaging (MRI) and change in anterior displacement of the psoas muscle from L1-L2 to L4-L5 discs. Overview of Literature/UNASSIGNED:Controversy exists in determining patient suitability for lateral lumbar interbody fusion (LLIF) based on psoas morphology. The effect of posture on psoas morphology has not previously been studied; however, lumbar MRI may be performed in sitting or supine positions. Methods/UNASSIGNED:A retrospective review of a single-spine practice over 6 months was performed, identifying patients aged between 18-90 years with degenerative spinal pathologies and lumbar MRIs were evaluated. Previous lumbar fusion, scoliosis, neuromuscular disease, skeletal immaturity, or intrinsic abnormalities of the psoas muscle were excluded. The anteroposterior (AP) dimension of the psoas muscle and intervertebral disc were measured at each intervertebral disc from L1-L2 to L4-L5, and the AP psoas:disc ratio calculated. The morphology was compared between patients undergoing sitting and/or supine MRI. Results/UNASSIGNED:Two hundred and nine patients were identified with supine-, and 60 patients with sitting-MRIs, of which 13 patients had undergone both sitting and supine MRIs (BOTH group). A propensity score match (PSM) was performed for patients undergoing either supine or sitting MRI to match for age, BMI, and gender to produce two groups of 43 patients. In the BOTH and PSM group, sitting MRI displayed significantly higher AP psoas:disc ratio compared with supine MRI at all intervertebral levels except L1-L2. The largest difference observed was a mean 32%-37% increase in sitting AP psoas:disc ratio at the L4-L5 disc in sitting compared to supine in the BOTH group (range, 0%-137%). Conclusions/UNASSIGNED:The psoas muscle and the lumbar plexus become anteriorly displaced in sitting MRIs, with a greater effect noted at caudal intervertebral discs. This may have implications in selecting suitability for LLIF, and intra-operative patient positioning.