Post-Operative Hyperextension Bracing Has the Potential to Reduce Proximal Junctional Kyphosis: A Propensity Matched Analysis of Braced versus Non-braced Cohorts.

STUDY DESIGN: Retrospective cohort. OBJECTIVE: Determine effects of bracing on proximal junctional kyphosis (PJK) after adult deformity correction. METHODS: Patients were identified from a single-surgeon dataset of posterior-only fusions for ASD (pelvis to UIV of T9-12) with a minimum of 1-year follow up. Starting in 2021, all lower thoracic fusions were braced using a hyperextension brace. Patients wore the brace at all times (unless in bed) for the first 6 weeks after surgery. A 1:1 propensity-match was performed based on age, number of levels, 3 column osteotomies, and magnitude of correction to identify a comparative non-braced cohort. RESULTS: 141 patients (113 non-brace, 28 brace) were evaluated. After matching, 56 patients were identified to form similar cohorts. Non-matched and matched groups had no statistically significant differences in demographics, comorbid conditions, surgical characteristics (except shorter operative time and lower EBL in the braced group), and preoperative radiographic parameters. For the overall cohort, the change in proximal junctional angle at 1-year was higher in the non-braced group (7.6° vs 8.1°, P = .047), and non-braced patients had a higher incidence of PJK at 1-year in both the overall cohort (36% vs 14%, P = .045) and matched cohort (43% vs 14%, P = .038). There was no difference in proximal junctional failure between groups. CONCLUSION: This pilot study shows that our protocol for extension bracing may reduce rates of PJK. These findings can form the basis for future multi-center trials examining the effect of extension bracing on junctional complications.

Why Didn't You Walk Yesterday? Factors Associated With Slow Early Recovery After Adult Spinal Deformity Surgery.

STUDY DESIGN: This is a retrospective case-control study. OBJECTIVES: The objectives of this study are to identify (1) risk factors for delayed ambulation following adult spinal deformity (ASD) surgery and (2) complications associated with delayed ambulation. METHODS: One-hundred and ninety-one patients with ASD who underwent posterior-only fusion (≥5 levels, LIV pelvis) were reviewed. Patients who ambulated with physical therapy (PT) on POD2 or later (LateAmb, n = 49) were propensity matched 1:1 to patients who ambulated on POD0-1 (NmlAmb, n = 49) based on the extent of fusion and surgical invasiveness score (ASD-S). Risk factors, as well as inpatient medical complications were compared. Logistic regressions were used to identify risk factors for late ambulation. RESULTS: Of the patients who did not ambulate on POD0-1, 32% declined participation secondary to pain or dizziness/fatigue, while 68% were restricted from participation by PT/nursing due to fatigue, inability to follow commands, nausea/dizziness, pain, or hypotension. Logistic regression showed that intraoperative estimated blood loss (EBL) >2L (OR = 5.57 [1.51-20.55], P = .010) was independently associated with an increased risk of delayed ambulation, with a 1.25 times higher risk for every 250 mL increase in EBL (P = .014). Modified 5-Item Frailty Index (mFI-5) was also independently associated with delayed ambulation (OR = 2.53 [1.14-5.63], P = .023). LateAmb demonstrated a higher hospital LOS (8.4 ± 4.0 vs 6.2 ± 2.6, P < .001). The LateAmb group trended toward an increase in medical complications on POD3+ (14.3% vs 26.5%, P = .210). CONCLUSIONS: EBL demonstrates a dose-response relationship with risk for delayed ambulation. Delayed ambulation increases LOS and may impact medical complications.

Quantifying the Contribution of Lower Limb Compensation to Upright Posture: What Happens If Adult Spinal Deformity Patients Do Not Compensate?

STUDY DESIGN: This is a multicenter, prospective cohort study. OBJECTIVE: This study tests the hypothesis that the elimination of lower limb compensation in patients with adult spinal deformity (ASD) will significantly increase the magnitude of sagittal malalignment. SUMMARY OF BACKGROUND DATA: ASD affects a significant proportion of the elderly population, impairing functional sagittal alignment and inhibiting the overall quality of life. To counteract these effects, patients with ASD use their spine, pelvis, and lower limbs to create a compensatory posture that allows for standing and mobility. However, the degree to which each of the hips, knees, and ankles contributes to these compensatory mechanisms has yet to be determined. METHODS: Patients undergoing corrective surgery for ASD were included if they met at least one of the following criteria: complex surgical procedure, geriatric deformity surgery, or severe radiographic deformity. Preoperative full-body x-rays were evaluated, and age and pelvic incidence -adjusted normative values were used to model spine alignment based upon three positions: compensated (all lower extremity compensatory mechanisms maintained), partially compensated (removal of ankle dorsiflexion and knee flexion, with maintained hip extension), and uncompensated (ankle, knee, and hip compensation set to the age and pelvic incidence norms). RESULTS: A total of 288 patients were included (mean age 60 yr, 70.5% females). As the model transitioned from the compensated to uncompensated position, the initial posterior translation of the pelvis decreased significantly to an anterior translation versus the ankle (P.Shift: 30 to -7.6 mm). This was associated with a decrease in pelvic retroversion (pelvic tilt: 24.1-16.1), hip extension (SFA: 203-200), knee flexion (knee angle: 5.5-0.4), and ankle dorsiflexion (ankle angle: 5.3-3.7). As a result, the anterior malalignment of the trunk significantly increased: sagittal vertical axis (65-120 mm) and G-SVA (C7-ankle from 36 to 127 mm). CONCLUSIONS: Removal of lower limbs compensation revealed an unsustainable truncal malalignment with two-fold greater SVA.

Cervicothoracic Versus Proximal Thoracic Lower Instrumented Vertebra Have Comparable Radiographic and Clinical Outcomes in Adult Cervical Deformity.

STUDY DESIGN: Comparative cohort study. OBJECTIVE: Factors that influence the lower instrumented vertebra (LIV) selection in adult cervical deformity (ACD) are less reported, and outcomes in the cervicothoracic junction (CTJ) and proximal thoracic (PT) spine are unclear. METHODS: A prospective ACD database was analyzed using the following inclusion criteria: LIV between C7 and T5, upper instrumented vertebra at C2, and at least a 1-year follow-up. Patients were divided into CTJ (LIV C7-T2) and PT groups (LIV T3-T5) based on LIV levels. Demographics, operative details, radiographic parameters, and the health-related quality of life (HRQOL) scores were compared. RESULTS: Forty-six patients were included (mean age, 62 years), with 22 and 24 patients in the CTJ and PT groups, respectively. Demographics and surgical parameters were comparable between the groups. The PT group had a significantly higher preoperative C2-C7 sagittal vertical axis (cSVA) (46.9 mm vs 32.6 mm, P = 0.002) and T1 slope minus cervical lordosis (45.9° vs 36.0°, P = 0.042) than the CTJ group and was more likely treated with pedicle-subtraction osteotomy (33.3% vs 0%, P = 0.004). The PT group had a larger correction of cSVA (-7.7 vs 0.7 mm, P = 0.037) and reciprocal change of increased T4-T12 kyphosis (8.6° vs 0.0°, P = 0.001). Complications and reoperations were comparable. The HRQOL scores were not different preoperatively and at 1-year follow-up. CONCLUSIONS: The selection of PT LIV in cervical deformities was more common in patients with larger baseline deformities, who were more likely to undergo pedicle-subtraction osteotomy. Despite this, the complications and HRQOL outcomes were comparable at 1-year follow-up.

Patterns of Lumbar Spine Malalignment Leading to Revision Surgery for Proximal Junctional Kyphosis: A Cluster Analysis of Over- Versus Under-Correction.

STUDY DESIGN: Retrospective cohort study. OBJECTIVE: Investigate the patterns of fused lumbar alignment in patients requiring revision surgery for proximal junctional kyphosis (PJK). METHODS: Fifty patients (67.8 yo, 76% female) with existing thoraco-lumbar fusion (T10/12 to pelvis) and indicated for surgical correction for PJK were included. To investigate patterns of radiographic alignment prior to PJK revision, unsupervised 2-step cluster analysis was run on parameters describing the fused lumbar spine (PI-LL) to identify natural independent groups within the cohort. Clusters were compared in terms of demographics, pre-operative alignment, surgical parameters, and post-operative alignment. Associations between pre- and post-revision PJK angles were investigated using a Pearson correlation analysis. RESULTS: Analysis identified 2 distinct patterns: Under-corrected (UC, n = 12, 32%) vs over-corrected (OC, n = 34, 68%) with a silhouette of .5. The comparison demonstrated similar pelvic incidence (PI) and PJK angle but significantly greater deformity for the UC vs OC group in terms of PI-LL, PI-LL offset, pelvic tilt, and sagittal vertebral axis. The surgical strategy for PJK correction did not differ between the 2 groups in terms of approach, American Society of Anesthesiologists grade, decompression, use of osteotomy, interbody fusion, or fusion length. The post-revision PJK angle significantly correlated with the amount of PJK correction within the OC group but not within the UC group. CONCLUSIONS: This study identified 2 patterns of lumbar malalignment associated with severe PJK: over vs under corrected. Despite the difference in PJK etiology, both patterns underwent the same revision strategy. Future analysis should look at the effect of correcting focal deformity alone vs correcting focal deformity and underlying malalignment simultaneously on recurrent PJK rate.

Predicting Mechanical Failure Following Cervical Deformity Surgery: A Composite Score Integrating Age-Adjusted Cervical Alignment Targets.

STUDY DESIGN: Retrospective cohort study. OBJECTIVES: Investigate a composite score to evaluate the relationship between alignment proportionality and risk of distal junctional kyphosis (DJK). METHODS: 84 patients with minimum 1 year follow-up were included (age = 61.1 ± 10.3 years, 64.3% women). The Cervical Score was constructed using offsets from age-adjusted normative values for sagittal vertical axis (SVA), T1 Slope (TS), and TS minus cervical lordosis (CL). Individual points were assigned based on offset with age-adjusted alignment targets and summed to generate the Cervical Score. Rates of mechanical failure (DJK revision or severe DJK [DJK> 20° and ΔDJK> 10°]) were assessed overall and based on Cervical Score. Logistical regressions assessed associations between early radiographic alignment and 1-year failure rate. RESULTS: Mechanical failure rate was 21.4% (N = 18), 10.7% requiring revision. By multivariate logistical regression: 3-month T1S (OR: .935), TS-CL (OR:0.882), and SVA (OR:1.015) were independent predictors of 1-year failure (all P < .05). Cervical Score ranged (-6 to 6), 37.8% of patients between -1 and 1, and 50.0% with 2 or higher. DJK patients had significantly higher Cervical Score (4.1 ± 1.3 vs .6 ± 2.2, P < .001). Patients with a score ≥3 were significantly more likely to develop a failure (71.4%) with OR of 38.55 (95%CI [7.73; 192.26]) and Nagelkerke r2 .524 (P < .001). CONCLUSION: This study developed a composite alignment score predictive of mechanical failures in CD surgery. A score ≥3 at 3 months following surgery was associated with a marked increase in failure rate. The Cervical Score can be used to analyze sagittal alignment and help define realignment objectives to reduce mechanical failure.

How Does Gravity Influence the Distribution of Lordosis in Patients With Sagittal Malalignment?

STUDY DESIGN: Retrospective cohort study. OBJECTIVE: Compare the supine vs standing radiographs of patients with adult spinal deformity against ideals defined by healthy standing alignment. METHODS: 56 patients with primary sagittal ASD (SRS-Schwab Type N) and 119 asymptomatic volunteers were included. Standing alignment of asymptomatic volunteers was used to calculate PI-based formulas for normative age-adjusted standing PI-LL, L4-S1, and L1-L4. These formulas were applied to the supine and standing alignment of ASD cohort. Analyses were repeated on a cohort of 25 patients with at least 5 degrees of lumbar flexibility (difference between supine and standing lordosis). RESULTS: The asymptomatic cohort yielded the following PI-based formulas: PI-LL = -38.3 + .41*PI + .21*Age, L4-S1 = 45.3-.18*Age, L1-L4 = -3 + .48*PI). PI-LL improved with supine positioning (mean 8.9 ± 18.7°, P < .001), though not enough to correct to age-matched norms (mean offset 12.2 ± 16.9°). Compared with mean normative alignment at L1-L4 (22.1 ± 6.2°), L1-L4 was flatter on standing (7.2 ± 17.0°, P < .001) and supine imaging (8.5 ± 15.0°, P < .001). L4-S1 lordosis of subjects with L1-S1 flexibility >5° corrected on supine imaging (33.9 ± 11.1°, P = 1.000), but L1-L4 did not (23.0 ± 6.2° norm vs 2.2 ± 14.4° standing, P < .001; vs 7.3 ± 12.9° supine, P < .001). CONCLUSIONS: When the effects of gravity are removed, the distal portion of the lumbar spine (i.e., below the apex of lordosis) corrects, suggesting that structural lumbar deformity is primarily proximal.

Cervical Paraspinal Muscle Fatty Infiltration is Directly Related to Extension Reserve in Patients With Cervical Spine Pathology.

STUDY DESIGN/SETTING: Retrospective review of a prospectively collected database. OBJECTIVE: The objective of this study was to determine the relationship between paracervical muscle area, density, and fat infiltration and cervical alignment among patients presenting with cervical spine pathology. BACKGROUND CONTEXT: The impact of cervical spine alignment on clinical outcomes has been extensively studied, but little is known about the association between spinal alignment and cervical paraspinal musculature. METHODS: We examined computed tomography scans and radiographs for patients presenting with cervical spine pathology. The posterior paracervical muscle area, density, and fat infiltration was calculated on axial slices at C2, C4, C6, and T1. We measured radiographic parameters including cervical sagittal vertical axis, cervical lordosis, T1 slope (T1S), range of motion of the cervical spine. We performed Pearson correlation tests to determine if there were significant relationships between muscle measurements and alignment parameters. RESULTS: The study included 51 patients. The paracervical muscle area was higher for males at C2 ( P =0.005), C4 ( P =0.001), and T1 ( P =0.002). There was a positive correlation between age and fat infiltration at C2, C4, C6, and T1 (all P <0.05). The cervical sagittal vertical axis positively correlated with muscle cross-sectional area at C2 ( P =0.013) and C4 ( P =0.013). Overall cervical range of motion directly correlated with muscle density at C2 ( r =0.48, P =0.003), C4 ( r =0.41, P =0.01), and C6 ( r =0.53. P <0.001) and indirectly correlated with fat infiltration at C2 ( r =-0.40, P =0.02), C4 ( r =-0.32, P =0.04), and C6 ( r =-0.35, P =0.02). Muscle density correlated directly with reserve of extension at C2 ( r =0.57, P =0.009), C4 ( r =0.48, P =0.037), and C6 ( r =0.47, P =0.033). Reserve of extension indirectly correlated with fat infiltration at C2 ( r =0.65, P =0.006), C4 ( r =0.47, P =0.037), and C6 ( r =0.48, P =0.029). CONCLUSIONS: We have identified specific changes in paracervical muscle that are associated with a patient's ability to extend their cervical spine.

Timing of inpatient medical complications after adult spinal deformity surgery: early ambulation matters.

BACKGROUND: The substantial risk for medical complication after adult spinal deformity (ASD) surgery is well known. However, the timing of medical complications during the inpatient stay have not been previously described. Accurate anticipation of complications and adverse events may improve patient counseling and postoperative management. PURPOSE: (1) Describe the rate of medical complication and adverse events by postoperative day after ASD surgery and (2) determine whether early ambulation is protective for complications. STUDY DESIGN/SETTING: Single institution retrospective cohort study. PATIENT SAMPLE: Two hundred thirty-five patients with ASD who underwent posterior-only fusion of the lumbar spine (≥5 levels to the pelvis) between 2013 and 2020. OUTCOME MEASURES: Medical complications, categorized per the International Spine Study Group-AO system (cardiopulmonary [CP], gastrointestinal [GI], central nervous system [CNS], infectious [nonsurgical site], and renal) and adverse events (postoperative blood transfusion, urinary retention, and electrolyte abnormalities). METHODS: Patients were identified from an institutional ASD database. Outcome measures were classified by the first postoperative day the event was recognized. Demographics, year of surgery, surgical factors, radiographic parameters, surgical invasiveness (ASD-S Index), frailty (Modified Frailty Index-5 [mFI-5]), Charlson Comorbidity Index (CCI), obstructive sleep apnea (OSA), smoking, preoperative opioid use, depression, and post-operative day of ambulation were assessed as risk factors for inpatient medical complications. RESULTS: After exclusions of patients with incomplete medical chart data, 191 patients were available for analysis, mean age 66±10 y, BMI 28±5 kg/m2, PI-LL 24±20°, T1PA 28±13°. Inpatient medical complications occurred in 55 (28.8%) patients; adverse events occurred in 137 (71.7%). Length of stay was higher in patients with medical complications (mean 8.5±3.8 vs. 5.8±2.3 days, p<.001). However, for patients who had an adverse event, but no medical complication, LOS was comparable (p>.05). Most medical complications occurred by POD3 (58% of all complications). Risk (defined as the proportion of patients with that complication out of all inpatients that day) of CNS, CP, and GI complication peaked early in the postoperative course (CNS on POD1 [2.1% risk]; GI on POD2 [3.7%]; CP on POD3 [2.7%]). Risk for infectious and renal complications (infectious POD8 [2.7%]; renal POD7 [0.9%]) peaked later (Figure 1). On univariate analysis, patients with medical complications had higher rates of OSA (9.1% vs. 2.2%, p=.045), ASD-S (45.9 vs. 40.8, p=.04), max coronal cobb (46.9 vs. 36.7°, p=.003), ASA class (2.5 vs. 2.3, p=.01), and POD of ambulation (1.9 vs. 1.3, p=.01). On multivariate logistic regression (c-statistic 0.78), larger coronal cobb and later POD of ambulation were independent risk factors for complications (OR 1.04, 95% CI 1.01-1.07 and OR 2.3, 95% CI 1.2-4.7, respectively). CONCLUSIONS: Our data may inform peri-operative management and patient expectations for hospitalization after ASD surgery. Early ambulation may reduce the risk of complications.

Can Discharge Radiographs Predict Junctional Complications? A Decision Tree Analysis.

STUDY DESIGN: Retrospective cohort study. OBJECTIVES: To determine if standing pre-discharge radiographs can predict the development of junctional complications. MATERIALS AND METHODS: Adult spinal deformity patients who underwent fusion of the lumbar spine (≥5 levels, LIV pelvis) were included. All patients underwent full-length standing radiographs before hospital discharge. Outcomes of interest included 2-year radiographic PJK and proximal junctional failure (PJF). Patients were stratified into 3 exclusive groups: No PJK, PJK, and PJF. Chi-square automatic interaction detection (CHAID) decision tree analysis was utilized to identify pre-discharge proximal junctional angle (PJA) thresholds associated with increased risk of PJK or PJF. RESULTS: The 117 study patients had a mean age 65.8 ± 8.5, BMI 27.2 ± 4.9, PI-LL 23.3 ± 17.4, TPA 27.2 ± 11.5. Sample was stratified into 64 (54.7%) No PJK, 39 (33.3%) PJK, 14 (12.0%) PJF. No differences were detected between cohorts in discharge alignment, preop-discharge change, or offset from age-adjusted alignment targets (P > .005). Decision tree analysis showed that the first branch point depended on the UIV, as most patients with an UT UIV did not develop PJK or PJF (no PJK, 67.4%). For patients with an LT UIV, a second branch point occurred based on the ΔPJA. 89.5% of LT patients with a ΔPJA < 4.3° were free of radiographic PJK and PJF. The third branch point occurred based on the PJA at discharge. Thus, the highest risk group was comprised of ΔPJA ≥4.3° and PJA > 15.5°, as 57.1% of developed PJF and 28.6% PJK. CONCLUSION: Most patients with a lower thoracic UIV, preop-discharge ΔPJA ≥4.3°, and discharge PJA > 15.5° develop PJF.

Shoulder Balance in Adult Spinal Deformity Patients Undergoing Selective Lumbar Fusion.

STUDY DESIGN: Retrospective review. OBJECTIVE: To analyze if shoulder balance continues to change in the postoperative period in patients undergoing selective lumbar fusion for adult spinal deformity (ASD), and secondarily, analyze if shoulder balance correlates with health-related quality of life (HRQOL) outcomes. SUMMARY OF BACKGROUND DATA: Shoulder balance in patients with ASD is poorly understood and has largely been extrapolated from adolescent scoliosis literature. MATERIALS AND METHODS: Adult patients who underwent selective lumbar fusion (upper instrumented vertebra: Τ9-Τ12, lower instrumented vertebra: L4-Pelvis) for thoracolumbar or lumbar scoliosis (cobb angle > 30°) or sagittal plane deformity with thoracic compensatory curves (cobb angle > 10°) were identified. The clavicular angle (CA) was used to quantify shoulder balance. Shoulder balance was categorized into three groups postoperatively (balanced: CA <2°, mild imbalance: CA 2°-4°, severe imbalance: CA >4°). The average CA and proportion of patients in each shoulder balance group were compared at each postoperative period. Patients with 1-year postoperative HRQOL scores were identified. RESULTS: Eighty-six patients were included. The preoperative CA was 2.7 ±â€Š2.3° and did not significantly change at discharge (2.9 ±â€Š2.4°), 6-weeks (2.5 ±â€Š2.1°), 6-months (2.4 ±â€Š2.2°), 1-year (2.4 ±â€Š2.5°), or 2-years (2.3 ±â€Š1.5°) postoperatively. The proportion of patients in each shoulder balance group did not significantly change from discharge to 6-weeks, 6-months, 1-year or 2-years postoperatively (P > 0.1). At 1-year follow-up, the CA demonstrated no significant correlation with Oswestry Disability Index, Scoliosis Research Society (SRS)-22 score, or SRS-22 subscores. There was no significant association between shoulder balance group and Oswestry Disability Index, SRS-22 score, or SRS-22 subscores. CONCLUSIONS: In patients with ASD undergoing selective lumbar fusion, shoulder balance did not change over the postoperative period. From a functional standpoint, shoulder balance demonstrated no correlation with HRQOL scores. In patients undergoing selective lumbar fusion for ASD, shoulder balance may not spontaneously correct over the postoperative period, but this may not be of functional consequence.Level of Evidence: 4.

Upper versus Lower Lumbar Lordosis Corrections in Relation to Pelvic Tilt - An Essential Element in Surgical Planning for Sagittal Plane Deformity.

STUDY DESIGN: Retrospective study of a multicenter Adult Spinal Deformity (ASD) Database. OBJECTIVE: To investigate the change in Pelvic tilt (PT) imparted by regional changes in lumbar lordosis at 2-year minimum follow up. SUMMARY OF BACKGROUND DATA: The distribution of lumbar lordosis between L1-4 and L4-S1 is known to vary based on pelvic incidence (PI). However, the extent to which regional changes effect PT is not clearly elucidated. This information can be useful for ASD surgical planning. METHODS: Operative patients from a multicenter ASD database were included with Lowest Instrumented Vertebrae (LIV) S1/Ilium, >5 levels of fusion, Proximal Junction Kyphosis (PJK) angle < 20, and >5 degrees of change in lumbar lordosis from L4-S1 and L1-4. Radiographic analysis was performed evaluating Thoracic Kyphosis (TK), T10-L2 kyphosis (TL), L1-S1 lordosis (LL), L4-S1 lordosis, L1-4 lordosis, sagittal vertical axis (SVA) and PI-LL from preoperative to postoperative, and change at 2-years follow-up. Stepwise regression analysis was performed in order to determine the relationship between PT and the above radiographic parameters. Health-related quality of life (HRQOL) outcomes were also compared between preoperative and postoperative timepoints at 2 years. RESULTS: 103 patients met inclusion for the study. There was improvement in all the radiographic parameters and HRQOLs at 2 years follow-up (p < 0.01). Stepwise regression model showed an inverse relationship between PT and LL change (r = 0.71, p < 0.01). Regionally, an increase in 10 degrees from L4-S1 correlated with a 2.4 degree decrease in PT (p < 0.01), while an increase in 10 degrees from L1-4 resulted in a 1.6 degree decrease in PT (p < 0.01). CONCLUSION: In the surgical planning for ASD, our data demonstrated significant correlational difference between corrections in the upper (L1-4) and lower (L4-S1) lumbar spine and PT changes. These calculations can be useful in planning sagittal plane corrections for ASD.

Radiographic Characteristics of Cervical Deformity (CD) Using a Discriminant Analysis: The Value of Extension Radiographs.

STUDY DESIGN: This was a retrospective review of a prospectively collected database. OBJECTIVE: The aim of this study was to delineate radiographic parameters that distinguish severe cervical spine deformity (CSD). SUMMARY OF BACKGROUND DATA: Our objective was to define parameters that distinguish severe CSD using a consensus approach combined with discriminant analysis as no system currently exists in the literature. METHODS: Twelve CSD surgeons reviewed preoperative x-rays from a CSD database. A consensus was reached for categorizing patients into a severe cervical deformity (sCD), non-severe cervical deformity (non-sCD), or an indeterminate cohort. Radiographic parameters were found including classic cervical and spinopelvic parameters in neutral/flexion/extension alignment. To perform our discriminant analysis, we selected for parameters that had a significant difference between the sCD and non-sCD groups using the Student t test. A discriminant function analysis was used to determine which variables discriminate between the sCD versus non-sCD. A stepwise analysis was performed to build a model of parameters to delineate sCD. RESULTS: A total of 146 patients with cervical deformity were reviewed (60.5±10.5 y; body mass index: 29.8 kg/m2; 61.3% female). There were 83 (56.8%) classified as sCD and 51 (34.9%) as non-sCD. The comparison analysis led to 16 radiographic parameters that were different between cohorts, and 5 parameters discriminated sCD and non-sCD. These parameters were cervical sagittal vertical axis, T1 slope, maximum focal kyphosis in extension, C2 slope in extension, and number of kyphotic levels in extension. The canonical coefficient of correlation was 0.689, demonstrating a strong association between our model and cervical deformity classification. The accuracy of classification was 87.0%, and cross-validation was 85.2% successful. CONCLUSIONS: More than one third of a series of CSD patients were not considered to have a sCD. Analysis of an initial 17 parameters showed that a subset of 5 parameters can discriminate between sCD versus non-sCD with 85% accuracy. Our study demonstrates that flexion/extension images are critical for defining severe CD.

Complication rate evolution across a 10-year enrollment period of a prospective multicenter database.

OBJECTIVE: Adult spinal deformity is a complex pathology that benefits greatly from surgical treatment. Despite continuous innovation, little is known regarding continuous changes in surgical techniques and the complications rate. The objective of the current study was to investigate the evolution of the patient profiles and surgical complications across a single prospective multicenter database. METHODS: This study is a retrospective review of a prospective, multicenter database of surgically treated patients with adult spinal deformity (thoracic kyphosis > 60°, sagittal vertical axis > 5 cm, pelvic tilt > 25°, or Cobb angle > 20°) with a minimum 2-year follow-up. Patients were stratified into 3 equal groups by date of surgery. The three groups' demographic data, preoperative data, surgical information, and complications were then compared. A moving average of 320 patients was used to visualize and investigate the evolution of the complication across the enrollment period. RESULTS: A total of 928/1260 (73.7%) patients completed their 2-year follow-up, with an enrollment rate of 7.7 ± 4.1 patients per month. Across the enrollment period (2008-2018) patients became older (mean age increased from 56.7 to 64.3 years) and sicker (median Charlson Comorbidity Index rose from 1.46 to 2.08), with more pure sagittal deformity (type N). Changes in surgical treatment included an increased use of interbody fusion, more anterior column release, and a decrease in the 3-column osteotomy rate, shorter fusion, and more supplemental rods and bone morphogenetic protein use. There was a significant decrease in major complications associated with a reoperation (from 27.4% to 17.1%) driven by a decrease in radiographic failures (from 12.3% to 5.2%), despite a small increase in neurological complications. The overall complication rate has decreased over time, with the lowest rate of any complication (51.8%) during the period from August 2014 to March 2017. Major complications associated with reoperation decreased rapidly in the 2014-2015. Major complications not associated with reoperation had the lowest level (21.0%) between February 2014 and October 2016. CONCLUSIONS: Despite an increase in complexity of cases, complication rates did not increase and the rate of complications leading to reoperation decreased. These improvements reflect the changes in practice (supplemental rod, proximal junctional kyphosis prophylaxis, bone morphogenetic protein use, anterior correction) to ensure maintenance of status or improved outcomes.

Sagittal age-adjusted score (SAAS) for adult spinal deformity (ASD) more effectively predicts surgical outcomes and proximal junctional kyphosis than previous classifications.

BACKGROUND: Several methodologies have been proposed to determine ideal ASD sagittal spinopelvic alignment (SRS-Schwab classification) global alignment and proportion (GAP) score, patient age-adjusted alignment). A recent study revealed the ability and limitations of these methodologies to predict PJK. The aim of the study was to develop a new approach, inspired by SRS classification, GAP score, and age-alignment to improve the evaluation of the sagittal plane. METHOD: A multi-center ASD database was retrospectively evaluated for surgically treated ASD patients with complete fusion of the lumbar spine, and minimum 2 year follow-up. The Sagittal age-adjusted score (SAAS) methodology was created by assigning numerical values to the difference between each patient's postoperative sagittal alignment and ideal alignment defined by previously reported age generational norms for PI-LL, PT, and TPA. Postoperative HRQOL and PJK severity between each SAAS categories were evaluated. RESULTS: 409 of 667 (61.3%) patients meeting inclusion criteria were evaluated. At 2 year SAAS score showed that 27.0% of the patients were under-corrected, 51.7% over-corrected, and 21.3% matched their age-adjusted target. SAAS score increased as PJK worsened (from SAAS = 0.2 for no-PJK, to 4.0 for PJF, p < 0.001). Post-operatively, HRQOL differences between SAAS groups included ODI, SRS pain, and SRS total. CONCLUSION: Inspired by SRS classification, the concept of the GAP score, and age-adjusted alignment targets, the results demonstrated significant association with PJK and patient reported outcomes. With a lower rate of failure and better HRQOL, the SAAS seems to represent a "sweet spot" to optimize HRQOL while mitigating the risk of mechanical complications.

Supine Imaging Is a Superior Predictor of Long-Term Alignment Following Adult Spinal Deformity Surgery.

STUDY DESIGN: Retrospective cohort study. OBJECTIVE: To investigate correlations between preoperative supine imaging and postoperative alignment. METHODS: A retrospective review was conducted of a single-institution database of patients with adult spinal deformity (ASD). Patients were stratified by fusion location in the lumbar or thoracic spine. Outcomes of interest were postoperative lumbar lordosis (LL) and thoracic kyphosis (TK). Sagittal alignment parameters were compared and correlation analyses were performed. Multilinear stepwise regression was conducted to identify independent predictors of postoperative LL or TK. Regression analyses were repeated within the lumbar and thoracic fusion cohorts. RESULTS: A total of 99 patients were included (mean age 63.2 years, 83.1% female, mean body mass index 27.3 kg/m2). Scoliosis Research Society classification demonstrated moderate to severe sagittal and/or coronal deformity (pelvic tile modifier, 18.2% ++; sagittal vertical axis, 27.3% ++, pelvic incidence minus lumbar lordosis mismatch, 29.3% ++, SRS type, 29.3% N type curve and 68.7% L or D type curve). A total of 73 patients (73.7%) underwent lumbar fusion and 50 (50.5%) underwent thoracic fusion. Correlation analyses demonstrated a significant association between pre- and postoperative LL and TK. Multilinear regression demonstrated that LL supine and pelvic incidence were significant predictors of postoperative LL (r2 = 0.568, P < .001). LL supine, TK supine, and age were significant predictors of postoperative TK (r2 = 0.490, P < .001). CONCLUSION: Preoperative supine films are superior to standing in predicting postoperative alignment at 1-year follow-up. Anticipation of undesired alignment changes through supine imaging may be useful in mitigating the risk of iatrogenic malalignment.

Surgical Planning for Adult Spinal Deformity: Anticipated Sagittal Alignment Corrections According to the Surgical Level.

STUDY DESIGN: Retrospective cohort study. OBJECTIVES: Establish simultaneous focal and regional corrective guidelines accounting for reciprocal global and pelvic compensation. METHODS: 433 ASD patients (mean age 62.9 yrs, 81.3% F) who underwent corrective realignment (minimum L1-pelvis) were included. Sagittal parameters, and segmental and regional Cobb angles were assessed pre and post-op. Virtual postoperative alignment was generated by combining post-op alignment of the fused spine with the pre-op alignment on the unfused thoracic kyphosis and the pre-op pelvic retroversion. Regression models were then generated to predict the relative impact of segmental (L4-L5) and regional (L1-L4) corrections on PT, SVA (virtual), and TPA. RESULTS: Baseline analysis revealed distal (L4-S1) lordosis of 33 ± 15°, flat proximal (L1-L4) lordosis (1.7 ± 17°), and segmental kyphosis from L2-L3 to T10-T11. Post-op, there was no mean change in distal lordosis (L5-S1 decreased by 2°, and L4-L5 increased by 2°), while the more proximal lordosis increased by 18 ± 16°. Regression formulas revealed that Δ10° in distal lordosis resulted in Δ10° in TPA, associated with Δ100 mm in SVA or Δ3° in PT; Δ10° in proximal lordosis yielded Δ5° in TPA associated with Δ50 mm in SVA; and finally Δ10° in thoraco-lumbar junction yielded Δ2.5° in TPA associated with Δ25 mm in SVA and no impact on PT correction. CONCLUSIONS: Overall impact of lumbar lordosis restoration is critically determined by location of correction. Distal correction leads to a greater impact on global alignment and pelvic retroversion. More specifically, it can be assumed that 1° L4-S1 lordosis correction produces 1° change in TPA / 10 mm change in SVA and 0.5° in PT.

The impact of preoperative supine radiographs on surgical strategy in adult spinal deformity.

OBJECTIVE: Preoperative planning for adult spinal deformity (ASD) surgery is essential to prepare the surgical team and consistently obtain postoperative alignment goals. Positional imaging may allow the surgeon to evaluate spinal flexibility and anticipate the need for more invasive techniques. The purpose of this study was to determine whether spine flexibility, defined by the change in alignment between supine and standing imaging, is associated with the need for an osteotomy in ASD surgery. METHODS: A single-center, dual-surgeon retrospective analysis was performed of adult patients with ASD who underwent correction of a thoracolumbar deformity between 2014 and 2018 (pelvis to upper instrumented vertebra between L1 and T9). Patients were stratified into osteotomy (Ost) and no-osteotomy (NOst) cohorts according to whether an osteotomy was performed (Schwab grade 2 or higher). Demographic, surgical, and radiographic parameters were compared. The sagittal correction from intraoperative prone positioning alone (sagittal flexibility percentage [Sflex%]) was assessed by comparing the change in lumbar lordosis (LL) between preoperative supine to standing radiographs and preoperative to postoperative alignment. RESULTS: Demographics and preoperative and postoperative sagittal alignment were similar between the Ost (n = 60, 65.9%) and NOst (n = 31, 34.1%) cohorts (p > 0.05). Of all Ost patients, 71.7% had a grade 2 osteotomy (mean 3 per patient), 21.7% had a grade 3 osteotomy, and 12.5% underwent both grade 3 and grade 2 osteotomies. Postoperatively, the NOst and Ost cohorts had similar pelvic incidence minus lumbar lordosis (PI-LL) mismatch (mean PI-LL 5.2° vs 1.2°; p = 0.205). Correction obtained through positioning (Sflex%) was significantly lower for in the osteotomy cohort (38.0% vs 76.3%, p = 0.004). A threshold of Sflex% < 70% predicted the need for osteotomy at a sensitivity of 78%, specificity of 56%, and positive predictive value of 77%. CONCLUSIONS: The flexibility of the spine is quantitatively related to the use of an osteotomy. Prospective studies are needed to determine thresholds that may be used to standardize surgical decision-making in ASD surgery.

Surgical Strategy for the Management of Cervical Deformity Is Based on Type of Cervical Deformity.

OBJECTIVES: Cervical deformity morphotypes based on type and location of deformity have previously been described. This study aimed to examine the surgical strategies implemented to treat these deformity types and identify if differences in treatment strategies impact surgical outcomes. Our hypothesis was that surgical strategies will differ based on different morphologies of cervical deformity. METHODS: Adult patients enrolled in a prospective cervical deformity database were classified into four deformity types (Flatneck (FN), Focal kyphosis (FK), Cervicothoracic kyphosis (CTK) and Coronal (C)), as previously described. We analyzed group differences in demographics, preoperative symptoms, health-related quality of life scores (HRQOLs), and surgical strategies were evaluated, and postop radiographic and HROQLs at 1+ year follow up were compared. RESULTS: 90/109 eligible patients (mean age 63.3 ± 9.2, 64% female, CCI 1.01 ± 1.36) were evaluated. Group distributions included FN = 33%, FK = 29%, CTK = 29%, and C = 9%. Significant differences were noted in the surgical approaches for the four types of deformities, with FN and FK having a high number of anterior/posterior (APSF) approaches, while CTK and C had more posterior only (PSF) approaches. For FN and FK, PSF was utilized more in cases with prior anterior surgery (70% vs. 25%). For FN group, PSF resulted in inferior neck disability index compared to those receiving APSF suggesting APSF is superior for FN types. CTK types had more three-column osteotomies (3CO) (p < 0.01) and longer fusions with the LIV below T7 (p < 0.01). There were no differences in the UIV between all deformity types (p = 0.19). All four types of deformities had significant improvement in NRS neck pain post-op (p < 0.05) with their respective surgical strategies. CONCLUSIONS: The four types of cervical deformities had different surgical strategies to achieve improvements in HRQOLs. FN and FK types were more often treated with APSF surgery, while types CTK and C were more likely to undergo PSF. CTK deformities had the highest number of 3COs. This information may provide guidelines for the successful management of cervical deformities.