Faculty Bibliography

OBJECTIVE:While health-related quality of life (HRQOL) measures have been extensively quantified in cervical deformity (CD), this clinical dimension has not yet been fully integrated into understanding CD radiographic subtypes prior to surgery. The aim of this study was to identify distinct patterns of HRQOL deficits among patients with CD by focusing on clinical scores and to examine the association of these patterns with radiographic morphotypes of CD. METHODS:This was a retrospective analysis of a prospective multicenter database of patients with CD aged 18 years or older. Patient-reported outcome measures consisted of the Neck Disability Index (NDI), modified Japanese Orthopaedic Association (mJOA) scale, and Swallowing Quality of Life (SWAL-QOL) questionnaire. After performing a principal component analysis on the individual questions of the NDI, mJOA, and SWAL-QOL, 4 factors with eigenvalues > 1 were retained and included in a cluster analysis to assign patients into homogeneous groups of outcomes. Moreover, a subgroup of patients with severe deformity was described and analyzed. RESULTS:Overall, 134 patients (59% female, mean age ± SD 60.9 ± 10.8 years) were included in this analysis. The mean HRQOL scores were NDI, 49.1 ± 17.6; mJOA, 13.5 ± 2.7; and EQ-5D, 0.7 ± 0.1). The factor analysis involving NDI, SWAL-QOL, and mJOA revealed 4 clusters. Cluster A represented patients with a predominant sleep problem. Cluster B was patients with the lowest neck disability. Cluster C represented the most disabled patients in terms of dysphagia and neck disability. Cluster D represented patients with myelopathy. Among the 71 patients with severe deformity, the distribution of cervical morphotypes significantly differed across the 4 clusters of disability (p = 0.009). Cluster C mainly consisted of patients with cervicothoracic deformity (66.7%, p = 0.002). Cluster D had a large proportion of patients (66.7%) with focal deformity (p = 0.007). In clusters A and B, 57.9% and 46.4% of patients, respectively, presented with "flat neck" deformity (p = 0.02). CONCLUSIONS:Distinct patterns of HRQOL deficits were observed across a heterogeneous population of patients with CD, and these patterns were associated with specific radiographic morphotypes. These findings provide a framework for the next generation of CD classification, wherein HRQOL measures are combined with radiographic parameters.

BACKGROUND:Pelvic tilt (PT) has been a parameter of interest in biomechanics of spinal deformity for decades. It remains unclear how patients achieve different values of PT pre- and postoperatively. RESEARCH QUESTION/OBJECTIVE:This study aimed at assessing the relative contribution of hip extension, knee flexion and ankle extension to PT, factoring malalignment and hip osteoarthritis (OA). METHODS:This retrospective study included Adult Spinal Deformity (ASD) patients with preoperative full-body radiographs from a multicenter database, with a sub-analysis of patients with complete 1-year follow-up (1yFU). Age and PI-adjusted normative PT (NormPT) and offset from norm (OffPT) were calculated, as for sacro-femoral angle (SFA), knee flexion angle (KA) and ankle angle (AA). Multivariate linear regression models controlling for age, frailty, severe hip OA, pelvic incidence (PI), SFA, and KA were used to predict PT at baseline, and offset from NormPT. Another model was generated to predict PT change. RESULTS:600 patients at baseline and 336 with 1yFU were included. Mean age was 61 ± 15, 70.2 % were females and 40 % were revision cases. At baseline, regression analysis revealed that 0.9° increase in hip extension (SFA) and a 0.6° increase in knee flexion (KA) amounted to 1° increase in PT. Knee and ankle contribution to PT significantly increased for while hip extension decreased as TPA augmented (p < 0.001). Patients with low deformity compensated with hip extension, while knee flexion was the largest contributor of PT in high deformity patients: 70.7 % (44.7 - 111.9). Median contribution of knee flexion to PT was larger for patients who presented hip OA. SIGNIFICANCE/CONCLUSIONS:This study demonstrated that PT is a phenomenon driven by extension of the hips and flexion of the knees and proposed values to predict PT from those two compensatory mechanisms. Magnitude of spinal deformity and hip OA alters the magnitude of SFA/KA contribution to PT.

OBJECTIVE:The aim of this retrospective study was to investigate the relationship between postoperative Roussouly sagittal profile changes and patient outcomes. METHODS:From a prospectively collected, single-center database, the authors reviewed the records of patients with adult spinal deformity (ASD) who had clinical and radiographic data from baseline to 2 years after surgery. The patients were stratified by their Roussouly curve type (current sacral slope-based and "theoretical" pelvic incidence-based types). Means comparison tests (ANOVA and chi-square) were used to assess differences among Roussouly groups. Backstep logistic regression analyses were used to analyze associations between Roussouly sagittal profile changes and patient outcomes, including minimum clinically important differences (MCIDs) in functional metrics. RESULTS:Five hundred twenty-five patients, 79% of whom were female, were included in this study. The mean age of the cohort was 60.8 ± 14.1 years, BMI was 27.2 ± 5.5 kg/m2, and Charlson Comorbidity Index score was 1.72 ± 1.68. According to the Roussouly classification, 8.3% of patients had a Roussouly type 1 (R1) curve, 53.6% type 2 (R2), 26.3% type 3 (R3), and 11.9% type 4 (R4). Overall, 39% of patients had a changed Roussouly shape postoperatively: 59% had R1, 58.5% R2, 48.1% R3, and 26.7% R4 (p < 0.001). Forty-eight percent of patients matched the theoretical Roussouly type postoperatively (41% R1, 41.5% R2, 51.9% R3, and 73.3% R4, p < 0.001). When controlling for baseline clinical and radiographic differences, the Roussouly type changes associated with a higher risk of proximal junctional kyphosis or proximal junctional failure were as follows: R1 to R2 (OR 2.5, 95% CI 1.1-5.6, p = 0.024), R2 to R4 (OR 2.8, 95% CI 1.1-7.7, p = 0.039), and R3 to R4 (OR 2.3, 95% CI 1.1-4.9, p = 0.033). R4 to R3 switches had the highest mechanical complication risks (OR 3.4, 95% CI 1.2-9.4, p = 0.016). R1 to R2 changes had the highest rate of attaining an MCID in the Oswestry Disability Index at 6 weeks (23.5%, p = 0.004). Roussouly type changes were not associated with differences in the MCID on the refined 22-item Scoliosis Research Society patient outcome questionnaire (SRS-22r) up to 2 years after surgery. CONCLUSIONS:While a significant portion of patients matched their postoperative theoretical Roussouly type, many of those matched at baseline were prone to become unmatched postoperatively. Postoperative Roussouly shape changes influence patient outcomes and should be accounted for when planning ASD surgery.

OBJECTIVE:The aim of this study was to determine if there are any specific procedural, demographic, and/or radiographic factors that are associated with an improved postoperative lower extremity (LE) motor score (LEMS) among patients with adult spinal deformity (ASD) and abnormal baseline LEMS undergoing surgical correction. METHODS:Patients with ASD enrolled in an observational prospective study from 2018 to 2023 at 13 spinal deformity centers in North America were queried. Eligible participants met at least one of the following radiographic and/or procedural inclusion criteria: pelvic incidence minus lumbar lordosis mismatch ≥ 25°, T1 pelvic angle ≥ 30°, SVA ≥ 15 cm, thoracic scoliosis ≥ 70°, thoracolumbar scoliosis ≥ 50°, global coronal malalignment ≥ 7 cm, underwent 3-column osteotomy (3CO), spinal fusion ≥ 12 levels, and/or age ≥ 65 years with ≥ 7 levels of instrumentation. Patients with a baseline abnormal LEMS were dichotomized based on whether the LEMS improved or deteriorated from baseline by the 6-week postoperative visit. Patients with a maintained LEMS by 6 weeks compared with baseline were excluded. Patient and operative characteristics were compared through bivariate analyses to assess differences in treatment. A multivariable logistic regression model was built to discern independent factors associated with improved LEMS while controlling for potential confounders. RESULTS:Of 121 patients (77 female, mean age 62.9 years) included in the study, 109 (90.1%) improved and 12 (9.9%) experienced further deterioration from baseline to 6 weeks. Both groups had similar baseline LEMS by laterality and per nerve root. The groups were similar in age, sex, comorbidities, baseline LEMS, BMI, surgical indication, number of instrumented levels, estimated blood loss, operating room time, and hospital length of stay (p > 0.05). No differences in radiographic parameters at baseline and 6 weeks were observed aside from patients whose score had deteriorated experiencing greater change in the L1 pelvic angle (∆L1PA) (-8.0° ± 8.3° vs -1.6° ± 7.6°, p = 0.0413). Despite having similar frequencies of lumbar decompressions performed across a similar number of levels, patients whose conditions had deteriorated at 6 weeks had fewer lumbar posterior column osteotomies (PCOs) performed (50% vs 82.6%, p = 0.0169). No differences in in the frequency and number of 3COs performed were observed. Patients whose score had deteriorated experienced greater intraoperative neurophysiological monitoring (IONM) changes (41.7% vs 8.3%, p = 0.0050), all of which were motor deficits. Controlling for ∆L1PA and IONM changes revealed lumbar PCOs to be an independent driver of improved LEMS (OR 4.99 [95% CI 1.05-23.70]), with excellent model performance (p = 0.0031, area under the receiver operating characteristic curve of 0.77, Hosmer-Lemeshow goodness-of-fit test p = 0.3017). CONCLUSIONS:Performing lumbar decompressions alone might not be enough to improve LE weakness in patients with ASD and preoperative motor impairment, while the use of PCO was beneficial for improvement. Thus, more aggressive and thorough decompressions afforded by a combined approach of lumbar PCOs and decompression should be considered in this patient population to optimize postoperative motor strength.

BACKGROUND AND OBJECTIVES/OBJECTIVE:The concept of upper cervical (C0-C2) extension reserve (ER) capacity, ER relaxation, and their impact on outcomes following surgical correction of adult cervical deformity (ACD) has not been extensively studied. We aimed to evaluate the impact of upper cervical ER on postoperative disability and outcomes. METHODS:Patients with ACD, from a retrospective cohort study of a prospectively collected multicenter database, undergoing subaxial cervical fusion with 2-year (2Y) follow-up data were included. ER was defined as: ΔC0-C2 sagittal Cobb angle between neutral and extension. Relaxation of ER was defined as the ER mean in those that met all ideal thresholds in radiographic parameters for Passias et al CD modifiers. We used multivariable logistic regression to adjust for confounding, with conditional inference tree approaches used to determine thresholds that affect postoperative ER resolution on patient-reported outcomes. RESULTS:A total of 108 patients with ACD met inclusion. Preoperative C0-C2 ER was 8.7° ± 9.0°, and at last follow-up was 10.3° ± 11.1°. Preoperatively 29% of the cohort had adequate ER, whereas 60% had improved ER postoperatively, with 50% achieving adequate ER by 2Y. Lower ER correlated with greater CD (P < .05). Preoperatively, greater ER had lower Neck Disability Index (P < .001). Controlled analysis found improved ER to have a greater likelihood of achieving Neck Disability Index minimum clinically important difference (odds ratio 6.94, [1.378-34.961], P = .019). In those with inadequate ER at baseline, the preoperative C2-C7 of < -18° and T1 slope-cervical Lordosis mismatch of >59° for T1 slope-cervical Lordosis mismatch was predictive of ER resolution. In those with preoperative C2-C7 >-18°, a T1PA of >13° was predictive of postoperative return of ER (all P < .05). Surgical correction of C2-C7 by > 16° from baseline was found to be predictive of ER return. CONCLUSION/CONCLUSIONS:Increased preoperative use of the C0-C2 ER in CD was associated with worse baseline regional and global alignment and adversely affected health-related measures. Most of the patients had ER relaxation postoperatively. In those who didn't, however, there was a decreased likelihood of achieving satisfactory outcomes.

PURPOSE/OBJECTIVE:To determine if iatrogenic posterior translation (UIV SPi) at the upper instrumented vertebrae (UIV) is associated with increased mechanical complications and secondarily to generate and validate a UIV SPi threshold for increased complications. METHODS:Two patient databases were utilized: one for generating a UIV SPi threshold and another for validation. Patients with a UIV between T8-L1 and a LIV at ilium were included. A receiver operating curve (ROC) curve analyses was performed to generate a threshold that predicted proximal junctional complications. This UIV SPi angle (-16.0°) was rounded to -15.0° for practical clinical use and validated in a separate cohort. Patients were stratified as above (most translated, MT) or below (least translated, LT) the threshold for comparative demographic and outcomes analyses. RESULTS:Generation of the threshold on 192 patients (122 LT, 70 MT) revealed that the MT group had higher absolute postoperative UIV SVA (MT=-56.1 ± 23.1 mm vs. LT=-10.4 ± 31.8 mm, p < 0.001), higher PT (25.7° vs. 19.3°, p < 0.001), and 2.8-5.8 times greater odds of postoperative proximal junctional complications at 2-years (p < 0.05). Validation on 135 patients (95 LT, 40 MT) revealed that the MT group had 11.7 times greater odds of radiographic PJK and had 4.5 times greater odds of all-cause reoperations (p < 0.05). CONCLUSION/CONCLUSIONS:Patients with UIV posterior translation, despite similar PI-LL and T1PA, exhibit a high PT and experience higher odds of proximal junctional complications. Our findings support limiting the UIV SPi to < 15° of posterior translation to mitigate postoperative mechanical complications. LEVEL OF EVIDENCE/METHODS:IV.

BACKGROUND AND OBJECTIVES/OBJECTIVE:To investigate the cost-effectiveness and impact of prophylactic techniques on the development of proximal junctional kyphosis (PJK) and proximal junctional failure (PJF) in the context of postoperative alignment. METHODS:Adult spinal deformity patients with fusion to pelvis and 2-year data were included. Patients receiving PJK prophylaxis (hook, tether, cement, minimally-invasive surgery approach) were compared to those who did not. These cohorts were further stratified into "Matched" and "Unmatched" groups based on achievement of age-adjusted alignment criteria. Costs were calculated using the Diagnosis-Related Group costs accounting for PJK prophylaxis, postoperative complications, outpatient health care encounters, revisions, and medical-related readmissions. Quality-adjusted life years were calculated using Short Form-36 converted to Short-Form Six-Dimension (SF-6D) and used an annual 3% discount rate. Multivariate analysis controlling for age, sex, levels fused, and baseline deformity severity assessed outcomes of developing PJK/PJF if matched and/or with use of PJK prophylaxis. RESULTS:A total of 738 adult spinal deformity patients met inclusion criteria (age: 63.9 ± 9.9, body mass index: 28.5 ± 5.7, Charlson comorbidity index: 2.0 ± 1.7). Multivariate analysis revealed patients corrected to age-adjusted criteria postoperatively had lower rates of developing PJK or PJF (odds ratio [OR]: 0.4, [0.2-0.8]; P = .011) with the use of prophylaxis. Among those unmatched in T1 pelvic angle, pelvic incidence lumbar lordosis mismatch, and pelvic tilt, prophylaxis reduced the likelihood of developing PJK (OR: 0.5, [0.3-0.9]; P = .023) and PJF (OR: 0.1, [0.03-0.5]; P = .004). Analysis of covariance analysis revealed patients matched in age-adjusted alignment had better cost-utility at 2 years compared with those without prophylaxis ($361 539.25 vs $419 919.43; P < .001). Patients unmatched in age-adjusted criteria also generated better cost ($88 348.61 vs $101 318.07; P = .005) and cost-utility ($450 190.80 vs $564 108.86; P < .001) with use of prophylaxis. CONCLUSION/CONCLUSIONS:Despite additional surgical cost, the optimization of radiographic realignment in conjunction with prophylaxis of the proximal junction appeared to be a more cost-effective strategy, primarily because of the minimization of reoperations secondary to mechanical failure. Even among those not achieving optimal alignment, junctional prophylactic measures were shown to improve cost efficiency.

BACKGROUND:Early-term complications may not predict long-term success after adult cervical deformity (ACD) correction. OBJECTIVE:Evaluate whether optimal realignment results in similar rates of perioperative complications but achieves longer-term cost-utility. STUDY DESIGN/METHODS:Retrospective cohort study. METHODS:ACD patients with 2-year data included. Outcomes: distal junctional failure (DJF), good clinical outcome (GCO):[Meeting 2 of 3: (1) NDI>20 or meeting MCID, (2) mJOA≥14, (3)NRS-Neck improved≥2]. Ideal Outcome defined as GCO without DJF or reoperation. Patient groups were stratified by correction to 'Optimal radiographic outcome', defined by cSVA 9 (<40 mm) AND TS-CL (<15 deg) upon correction. Cost calculated by CMS.com definitions, and cost-per-QALY was calculated by converting NDI to SF-6D. Multivariable analysis controlling for age, baseline T1-slope, cSVA, disability, and frailty, was used to assess complication rates, clinical outcomes, and cost-utility based on meeting optimal radiographic outcome. RESULTS:One hundred forty-six patients included: 52 optimal radiographic realignment (O) and 94 not optimal (NO). NO group presented with higher cSVA and T1-slope. Adjusted analysis showed O group suffered similar 90-day complications (P>0.8), but less DJK, DJF (0% vs. 18%; P<0.001) and reoperations (18% vs. 35%; P=0.02). Patients meeting optimal radiographic criteria more often met Ideal outcome [odds ratio: 2.2, (1.1-4.8); P=0.03]. Despite no differences in overall cost, O group saw greater clinical improvement, translating to a better cost-utility [mean difference: $91,000, ($49,000-$132,000); P<0.001]. CONCLUSION/CONCLUSIONS:Despite similar perioperative courses, patients optimally realigned experienced less junctional failure, leading to better cost-utility compared with those sub-optimally realigned. Perioperative complication risk should not necessarily preclude optimal surgical intervention, and policy efforts might better focus on long-term outcome measures in adult cervical deformity surgery. LEVEL OF EVIDENCE/METHODS:Level III.

BACKGROUND AND OBJECTIVES/OBJECTIVE:The spectrum of patients requiring adult spinal deformity (ASD) surgery is highly variable in baseline (BL) risk such as age, frailty, and deformity severity. Although improvements have been realized in ASD surgery over the past decade, it is unknown whether these carry over to high-risk patients. We aim to determine temporal differences in outcomes at 2 years after ASD surgery in patients stratified by BL risk. METHODS:Patients ≥18 years with complete pre- (BL) and 2-year (2Y) postoperative data from 2009 to 2018 were categorized as having undergone surgery from 2009 to 2013 [early] or from 2014 to 2018 [late]. High-risk [HR] patients met ≥2 of the criteria: (1) ++ BL pelvic incidence and lumbar lordosis or SVA by Scoliosis Research Society (SRS)-Schwab criteria, (2) elderly [≥70 years], (3) severe BL frailty, (4) high Charlson comorbidity index, (5) undergoing 3-column osteotomy, and (6) fusion of >12 levels, or >7 levels for elderly patients. Demographics, clinical outcomes, radiographic alignment targets, and complication rates were assessed by time period for high-risk patients. RESULTS:Of the 725 patients included, 52% (n = 377) were identified as HR. 47% (n = 338) had surgery pre-2014 [early], and 53% (n = 387) underwent surgery in 2014 or later [late]. There was a higher proportion of HR patients in Late group (56% vs 48%). Analysis by early/late status showed no significant differences in achieving improved radiographic alignment by SRS-Schwab, age-adjusted alignment goals, or global alignment and proportion proportionality by 2Y (all P > .05). Late/HR patients had significantly less poor clinical outcomes per SRS and Oswestry Disability Index (both P < .01). Late/HR patients had fewer complications (63% vs 74%, P = .025), reoperations (17% vs 30%, P = .002), and surgical infections (0.9% vs 4.3%, P = .031). Late/HR patients had lower rates of early proximal junctional kyphosis (10% vs 17%, P = .041) and proximal junctional failure (11% vs 22%, P = .003). CONCLUSION/CONCLUSIONS:Despite operating on more high-risk patients between 2014 and 2018, surgeons effectively reduced rates of complications, mechanical failures, and reoperations, while simultaneously improving health-related quality of life.

OBJECTIVE:Malalignment following cervical spine deformity (CSD) surgery can negatively impact outcomes and increase complications. Despite the growing ability to plan alignment, it remains unclear whether preoperative goals are achieved with surgery. The objective of this study was to assess how good surgeons are at achieving their preoperative goal alignment following CSD surgery. METHODS:Adult patients with CSD were prospectively enrolled into a multicenter registry. Surgeons documented alignment goals prior to surgery, including C2-7 sagittal vertical axis (SVA), C2-7 sagittal Cobb angle, T1 slope minus cervical lordosis (TS-CL), and C7-S1 SVA. Goals were compared with achieved alignment, and the offsets (achieved goal) were calculated. General linear models were created for offset magnitude for each alignment parameter, controlling for baseline deformity and surgical factors. RESULTS:The 88 enrolled patients had a mean age of 63.6 ± 13.0 years. The mean number of anterior and posterior instrumented levels was 3.5 ± 1.0 and 10.6 ± 4.5, respectively. Surgeons failed to achieve their preoperative alignment goals by an average of 17.2 (range 0.1-75.4) mm for C2-7 SVA, 10.3° (range 0.1°-45.5°) for C2-7 sagittal Cobb angle, 15.6° (range 0.0°-42.9°) for TS-CL, and 34.2 (range 0.3-113.7) mm for C7-S1 SVA. The sagittal alignment parameters with the highest rate of extreme outliers were TS-CL and C7-S1 SVA, with 32.2% exceeding 20° and 60.8% exceeding 20 mm from goal alignment, respectively. After controlling for baseline deformity and operative parameters, the only factor associated with achieving targeted alignment for C2-7 sagittal Cobb angle was greater baseline thoracic kyphosis (TK; B = -0.148, 95% CI -0.288 to -0.007, p = 0.040), and for TS-CL, the only associated factor was lower baseline TS-CL (B = 0.187, 95% CI 0.027-0.347, p = 0.022). Both lower TK and greater TS-CL may reflect increased baseline deformity through greater thoracic compensation and increased TS-CL mismatch, respectively. No significant associations were identified for C2-7 SVA and C7-S1 SVA. CONCLUSIONS:Surgeons failed to achieve their preoperative alignment goals by an average of 17.2 mm for C2-7 SVA, 10.3° for C2-7 sagittal Cobb angle, 15.6° for TS-CL, and 34.2 mm for C7-S1 SVA. The few factors identified that were associated with offset between goal and achieved alignment suggest that achievement of goal alignment was most challenging for more severe deformities. Further advancements are needed to enable more consistent translation of preoperative alignment goals into the operating room for adult CSD correction. Clinical trial registration no.: NCT01588054 (ClinicalTrials.gov).