Faculty Bibliography

BACKGROUND CONTEXT: Previous orthopedic literature has shown that patients with diabetes mellitus (DM) are more likely to develop complications in the postoperative period. To date, however, no study has assessed the specific pre- and postoperative risk factors that may contribute to this association for diabetic patients undergoing adult spinal deformity surgery. PURPOSE: Establish relevant risk factors for postoperative complications in a cohort of diabetic patients undergoing spinal deformity surgery. STUDY DESIGN/SETTING: Single-center retrospective cohort study. PATIENT SAMPLE: A total of 138 patients with DM who underwent spinal deformity surgery at a single academic hospital from 2012-2019. OUTCOME MEASURES: Primary outcomes were the development of any post-operative complications. These complications included the development of neurologic complications, urinary complications, cardiac complications, pulmonary complications, venous thromboembolism (VTE) and surgical site infections (SSI).
METHOD(S): This study is a retrospective cohort review of diabetic patients undergoing spinal deformity surgery, with 5 levels fused at a single academic medical center. Patients' age, BMI, levels fused, pre- and postoperative hemoglobin (Hgb), hematocrit (HCT) and preoperative HbA1C were collected. T-test and chi-square analyses were used to compare relevant outcomes. Significance was set to p<0.05.
RESULT(S): A total of 138 patients with DM met the inclusion criteria and were included in the analysis. Of these, 50.7% of the total cohort developed a postoperative complication within 90 days of the index surgery. Patients who developed postoperative complications were noted to have significantly lower postoperative Hgb (9.82+/-1.46 g/dL vs 10.72+/-1.76 g/dL, p=0.002) postoperative HCT (28.8+/-3.92% vs 32.60+/-4.61%, p<0.001) and significantly greater number of levels fused (9.49+/-3.74 vs 7.47+/-3.16, p=0.001). Diabetic patients who developed cardiac complications had significantly lower postoperative Hgb (9.47+/-1.50 g/dL vs 10.40+/-1.66 g/dL, p=0.021) and HCT (27.87+/-3.16% vs 31.15+/-4.72%, p=0.003) compared with those who did not. Diabetic patients who developed urinary complications were noted to be older on average (72.56+/-8.20 vs 64.43+/-11.70 years, p=0.043), while patients who developed VTE and pulmonary complications were noted to have significantly higher numbers of levels fused (VTE: 14.00+/-3.61 vs 8.37+/-3.51, p=0.007; PC: 10.82+/-4.14 vs 8.29+/-3.49, p=0.025)Finally, diabetic patients who developed a surgical site infection had significantly lower postoperative HCT (26.74+/-3.27% vs 30.86+/-4.64%, p=0.022) than those who did not. Multivariate logistic regression analysis showed that postoperative HCT (OR: 0.765 [0.613-1.098], p=0.001) and number of levels fused (OR: 1.243 [1.084-1.425], p=0.002) were predictive of development of any postoperative complication, when controlled for BMI, age, and and postoperative Hgb. Postoperative HCT was an independent predictor of the development of cardiac complications (OR: 0.827 [0.692-0.989], p=0.037) and SSI (OR: 0.709 [0.528-0.952], p=0.022).
CONCLUSION(S): Postoperative HCT is predictive of the development of postoperative complications in general, and more specifically the development of cardiac complications and surgical site infections. Along with blood-glucose and HbA1C, it should be closely monitored perioperatively in diabetic patients undergoing spinal deformity surgery. FDA DEVICE/DRUG STATUS: This abstract does not discuss or include any applicable devices or drugs.
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BACKGROUND CONTEXT: Adult spinal deformity (ASD) refers to multiple types of spinal deformity. This study used a prospective multicenter database of patients with "complex" surgical ASD to derive a data-driven classification of different deformity patterns, and assessed if such patterns have distinct clinical outcomes. PURPOSE: Use an AI-based unsupervised approach to identify patterns of ASD. STUDY DESIGN/SETTING: Retrospective analysis of a multi-center prospective database. PATIENT SAMPLE: A total of 286 patients with complex ASD who underwent surgical correction. OUTCOME MEASURES: Operative decision-making and 30-day adverse events.
METHOD(S): Complex surgical ASD included severe deformity, surgical complexity or advanced age with a multilevel fusion. An unsupervised cluster analysis that allowed for 10% outliers was used to identify different patterns of deformity. Perioperative outcomes of these clusters were then compared using ANOVA, Kustal-Wallis, and Chi-Squared analyses as indicated, with p-value < 0.05 considered significant.
RESULT(S): The Hyper-Kyphosis (Hyper TK, n = 31) group had a mean thoracic kyphosis of 82.6+/-17.6degree, lumbar hyperextension (PI-LL: -20.4+/-14.7degree) and relatively straight coronal curvatures. Hyper-Kyphosis patients were the youngest (mean age 48+/-20 years) and had the lowest disability (mean ODI 32.9+/-17.1) and pain scores (median NRS back 6 IQR 3 to 8, median NRS leg 1 IQR 0 to 4). The Severe Coronal (Coronal, n = 91) group had a mean thoracic Cobb of 44.7+/-17.8degree and a mean thoraco-lumbar Cobb of 57.9+/-16.5degree with preserved global sagittal alignment. Coronal patients had moderate disability (mean ODI 33.5+/-18.8), functional impairment (PCD: 34.4+/-12.3) and pain scores (median NRS back 7 IQR 5 to 8, median NRS leg 4 IQR 0 to 7). The Severe Sagittal (Sev. Sag. n=79) group had a severe spino-pelvic mismatch (42.9+/-12.9degree) and global sagittal deformity (24.3+/-7.9degree). Sev Sag had higher BMIs (28.9+/-5.9), high levels of disability (mean ODI 49.3+/-15.6) and low appearance scores (2.3+/-0.7). Finally, the Moderate Sagittal (Mod. Sag. n=85) group had moderate deformities without distinctive radiographic characteristics, a mean age of 68.8+/-7.8degree, the highest PROMIS pain interference sub-scores (65.2+/-5.8), high levels of disability (mean ODI 47.6+/-15.3) and back pain (NRS back 7 IQR 6 to 9), and poor overall quality of life (mean SRS total 2.8+/-0.6). Thirty-day adverse events were equivalent. Hyper TK and Coronal patients had the longest constructs, but fusion to the pelvis was most common in Mod Sag (89.4%) and Sev Sag (97.5%) deformities. Coronal patients had more osteotomies per case (median 11 IQR 6.5 to 14), longer OR times, and more 30-day implant-related complications (5.5%). Sev Sag and Hyper TK patients were more likely to require a 3-column osteotomy (43% and 32.3%, respectively). Sev Sag deformities were more likely to require interbody implants (29.1%) and operative wound debridement (7.6%). Hyper TK patients had shorter hospital stays.
CONCLUSION(S): AI methodologies identified 4 distinct patient clusters within a large population of surgically treated ASD patients. Each ASD cluster presented with 1) a unique spinal deformity pattern, 2) reported distinct pathognomonic health deficits, 3) received consistent surgical treatment across 11 centers, and 4) had characteristic perioperative complications and hospital stays. FDA DEVICE/DRUG STATUS: This abstract does not discuss or include any applicable devices or drugs.
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BACKGROUND CONTEXT: Tranexamic acid (TXA) is commonly used to lower blood loss in ASD surgery. Despite widespread use of TXA in ASD surgery, there is a lack of consensus regarding the optimal dosing intraoperatively. PURPOSE: This study aims to assess differences in blood loss and complications between high-dose, medium-dose, and low-dose TXA regimens. Complex ASD patients who receive high-dose TXA will have decreased blood loss compared to those who receive low-dose TXA. STUDY DESIGN/SETTING: Retrospective Review. PATIENT SAMPLE: A total of 265 ASD patients in a multi-center prospective study were retrospectively analyzed. OUTCOME MEASURES: Blood loss (ml), Major Blood Loss (>90th percentile ml), units transfused intraoperatively, units transfused perioperatively.
METHOD(S): Patients were separated into three cohorts by TXA regimen: 1) low-dose patients had =20mg/kg loading dose with =2mg/kg/hr maintenance dose 2) medium-dose patients had 20-50 mg/kg loading dose with 2-5 mg/kg/hr maintenance dose. 3) high-dose patients had =50mg/kg loading dose with =5mg/kg/hr maintenance dose. Major or minor blood loss was defined as above or below the 90th percentile of our cohort respectively. Multivariable analysis controlled for levels fused, BMI, platelets, Hgb, OR time, 3CO, and radiographic alignment.
RESULT(S): Fifty-four (20%) patients received low-dose regimen, 133 (50%) received medium-dose and 80 (30%) received high dose. Mean blood loss was 1,551+/-1,295 ml, intraoperative units RBCs 1.52+/-2, and perioperative units RBCs 2.3+/-2.3. Mean major blood loss was 4,566+/-1,516ml and minor blood loss 1,236+/-755ml. Compared to the low-dose group, patients in the high-dose group had 77.8% decreased odds of major blood loss (OR 0.222; P=0.007), decreased blood loss (Coef. -540.92ml; P=0.019), units transfused intraoperatively (Coef. -.739 units; P < 0.001), and units transfused perioperatively (Coef. -0.328 units; P=0.025). Compared to medium-dose group, the high-dose group had less units transfused intraoperatively (Coef. -.59 units; P < 0.001) and perioperatively (Coef. -.42 units; P < 0.001) with no difference in blood loss. There was no difference between the medium and low dose groups in blood loss or units transfused. There was no association between high-dose TXA regimen and increased rates of DVT, PE, or any medical complication before six weeks. No patients had a seizure.
CONCLUSION(S): In this multicenter prospectively collected database, ASD patients receiving high-dose intraoperative TXA have decreased odds of major blood loss, less RBC transfusions intraoperatively and 540ml less blood loss compared to low dose TXA, without additional risk of seizure or thromboembolic complications. FDA DEVICE/DRUG STATUS: This abstract does not discuss or include any applicable devices or drugs.
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BACKGROUND CONTEXT: Several studies have suggested that Hounsfield units (HU) in the spine are associated with increased complications for adult spinal deformity (ASD) patients. PURPOSE: The aim of this study is to assess whether there exists a threshold for HU that is associated with increased blood loss following ASD surgery. We hypothesize that HU below thresholds on spinal CT are predictive of increased blood loss during surgery and implant complications within 90 days after surgery for ASD. STUDY DESIGN/SETTING: Retrospective analysis. PATIENT SAMPLE: ASD patients who had HU measured in the spine were identified from a multicenter database. OUTCOME MEASURES: High Intraoperative blood loss and implant complications within 90 days of surgery.
METHOD(S): HU at L1, upper instrumented vertebrae (UIV) and total averages were assessed. Threshold linear regression with Bayesian information criteria was utilized to identify optimal cut-offs for predicting high blood loss (>2100mL, top 25% by volume) or any implant complications within 90 days. Implant complications included loosening, breakage and dislocation of rods or screws. Multivariable logistic regression was utilized controlling for age, gender, comorbidity, osteotomy and levels fused.
RESULT(S): Of 527 patients included, the mean age was 61+/-14. Mean L1 HU was 154.59+/-87, UIV HU was 175.1+/-304, and total average HU was 165+/-168. There were 59 patients with high blood loss (mean 5,026+/-233ml) and 467 with low blood loss (1,331+/-39.5ml). Threshold regression analysis identified that a cut-off of =140.33 was optimal for predicting high blood loss and =99.75 total average HU was optimal for predicting implant complications within 90 days of surgery. On multivariable analysis, L1 HU less than 140 was associated with 1.57x higher odds of high blood loss (P=0.032). Total average HU less than 100 was associated with a 3.6x higher odds of having an implant related failure within 90 days of surgery (P=0.035).
CONCLUSION(S): In this prospective multi-center study, Those with L1 HU=140 had a 1.52x higher odds of high blood loss. Patients with an average HUof =100 have 3.6x higher odds of implant related complication within 90 days of surgery. FDA DEVICE/DRUG STATUS: This abstract does not discuss or include any applicable devices or drugs.
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BACKGROUND CONTEXT: Sacralization of L5 is a condition that affects 15% of the population. Because of the increased L5 articulations to the sacrum, it is unclear how pelvic incidence and spinopelvic parameters should be measured. PURPOSE: Determine whether patients with L5 sacralization should be radiographically measured with relation to the L5 or S1 vertebrae. STUDY DESIGN/SETTING: Retrospective analysis. PATIENT SAMPLE: Prospective multicenter adult spinal deformity database. OUTCOME MEASURES: ODI, SF36 PCS, radiographic spinopelvic parameters.
METHOD(S): Linear regression modeling was used to determine normative TPA and PI-LL based on PI and age in a database of asymptomatic subjects. In an adult spinal deformity database, patients with radiographic evidence of L5 sacralization, had PI, LL and TPA measured from the superior endplate S1 and then also from L5. Patients with instrumentation below L4 at baseline were excluded. The differences in TPA and PI-LL from normative were calculated in the sacralization cohort relative to L5 and S1 and correlated to ODI. Patients were grouped based on PI-LL Schwab modifier (0, +, ++) utilizing their L5 PI-LL and S1 PI-LL. Baseline ODI and SF36 PCS were compared across and within groups and their respective SRS Schwab class.
RESULT(S): Among 1,179 ASD patients, 276 (23.4%) had transitional anatomy, 176 with sacralized L5 (14.9%) and 100 (8.48%) with lumbarization of S1. The 176 with sacralized L5 were analyzed. PI (24.5 +/- 11.0 vs 55.7 +/- 12.0, p=0.001), TPA (11.2 +/- 12.0 vs 20.3 +/- 12.5, p=0.001) and PI-LL (0.67 +/- 21.1 vs 11.4 +/- 20.8, p=0.001) measured utilizing the L5 superior endplate were significantly smaller than those who were measured relative to S1. When measured from S1, 76 (43. %) of patients were SRS Schwab 0, 45 (25.6%) were Class +, and 55 (31.3%) were class ++ compared to 124 (70.5%), 22 (12.5%), and 30 (17.0%) measured from L5 respectively. There were significant differences in ODI and PCS as the Schwab grade increased regardless of L5 or S1 measurement. The L5 group had higher PCS functional scores for Schwab 0 and ++ relative to same grades in the S1 group. Offset from normative TPA (0.5 +/- 11.1 vs 9.6 +/- 10.8, p=0.001) and PI-LL (0.67 +/- 21.1 vs 11.4 +/- 20.8, p=0.001) were smaller when measuring from L5. Moreover, S1 measurements were more correlated with disability by ODI (TPA offset from normative, S1: R=0.326 vs L5: R=0.285; PI-LL Offset from normative, S1: R=0.318 vs L5: R=0.274).
CONCLUSION(S): Measuring the PI at L5 in sacralized anatomy results in underestimating the PILL Schwab grade in a percentage of patients and less correlation with HRQLs. Patients with sacralized L5s should have spinopelvic parameters measured relative to S1. FDA DEVICE/DRUG STATUS: This abstract does not discuss or include any applicable devices or drugs.
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BACKGROUND CONTEXT: Previous literature has demonstrated the advantages of lateral single position surgery (L-SPS) in the perioperative period; however, 2-year postoperative outcomes of this novel technique have not yet been compared to circumferential anterior-posterior fusion (FLIP) at 2-years postoperatively. PURPOSE: Evaluate the feasibility and safety of L-SPS technique against the conventional FLIP. STUDY DESIGN/SETTING: Multi-center retrospective cohort study. PATIENT SAMPLE: Patients undergoing primary AP (ALIF or LLIF) fusions with bilateral percutaneous pedicle screw fixation between L2-S1 with minimum 2-year followup at three institutions. OUTCOME MEASURES: Outcome measures included levels fused, operative time, estimated blood loss and perioperative complications. Radiographic analysis included lumbar lordosis (LL), pelvic incidence (PI), pelvic tilt (PT), PI-LL mismatch and segmental lumbar lordosis.
METHOD(S): Patients were grouped as L-SPS if anterior and posterior portions of the procedure were performed in the lateral decubitus position, and FLIP if patients were repositioned from supine or lateral to prone position for the posterior portion of the procedure. Groups were compared in terms of demographics, intraoperative, perioperative and radiological outcomes, complications and reoperations up to 2 years follow-up. Measures were compared using independent samples or paired t-tests and chi-squared analyses with significance set at p<0.05.
RESULT(S): A total of 442 pts met inclusion, including 352 L-SPS and 90 FLIP pts. Significant differences were noted in age (62.4 vs. 56.9; p= < 0.001) and smoking status (7% vs. 16%; p=0.023) between the L-SPS and FLIP groups. No differences between L-SPS and FLIP were noted in gender (57.4% female vs 57.8% female, p=1.000), BMI (30.0kg/m2 vs 29.3kg/m2; p=0.318). No differences were noted in number of levels fused between L-SPS and FLIP (1.45vs 1.50; p=0.533), proportion including ALIF (38% vs 39%; p=0.809), or the proportion of surgeries including L5-S1 (38%vs 31%; p=0.222). Perioperative outcomes: L-SPS demonstrated significantly lower Op time (97.7min vs 297.0 min; p < 0.001), fluoro dose (36.5mGy vs 78.8mGy; p < 0.001), EBL (88.8mL vs 270.0mL; p < 0.001), and LOS (1.91 days vs. 3.61 days; p < 0.001) compared to FLIP. L-SPS also demonstrated significantly fewer post-op complications than FLIP (21.9% vs 34.4%; p=0.013), specifically regarding rates of ileus (0.0% vs 5.6%; p < 0.001). There was no difference in remaining surgical site, neurological, or medical complications between groups. Reoperation: N=no differences in reoperation were noted at 30-day (1.7%L-SPS vs 4.4%FLIP, p=0.125), 90-day (5.1%L-SPS vs 5.6%FLIP, p=0.795) or 2-year follow-up (9.7%L-SPS vs 12.2%FLIP; p=0.441). The most common reason for return to OR was Adjacent Segment Disease, (L-SPS 3.1% vs. FLIP 7.8%; p=0.067). Pseudarthrosis rates were similar between groups (0.0%L-SPS vs. 1.1%FLIP; p=0.204). Radiological Outcomes: no significant differences were noted in rates of radiological fusion (94.3% L-SPS vs 97.8%FLIP; p=0.266) or subsidence (6.9%L-SPS vs 12.2%FLIP; p=0.260). There were no differences noted between L-SPS and FLIP in change in LL from Baseline to 1-year (3.5 vs 2.8; p=0.466) and post-op to 1yr (-0.18 vs -0.51; p=0.777), or in PI-LL from Baseline to 1-year (-3.5 vs -3.2; p=0.835) and from post-op to 1-year (0.71 vs 0.71; 0.998).
CONCLUSION(S): L-SPS improves safety, improves operative efficiency and reduces complications in the perioperative period while maintaining similar efficacy of AP fusion at 2-year followup in treating degenerative lumbar spinal conditions. FDA DEVICE/DRUG STATUS: This abstract does not discuss or include any applicable devices or drugs.
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BACKGROUND CONTEXT: Surgical intervention has been shown to be an effective treatment modality for adult cervical deformity (CD), yet patient-reported outcomes vary even when patients are optimally realigned. While patients with higher baseline disability have more room for improvement, we propose there may be a threshold beyond which greater disability limits health-related quality of life (HRQL) improvement due to elevated risks and a point of no return. PURPOSE: To assess impact of baseline disability on HRQL outcomes. STUDY DESIGN/SETTING: Retrospective study of prospectively enrolled CD patients in a multicenter CD database. PATIENT SAMPLE: A total of 116 CD patients were included. OUTCOME MEASURES: HRQL, neck disability index (NDI), modified Japanese Orthopaedic Association (mJOA), EuroQol-5 Dimension (EQ5D).
METHOD(S): CD patients with baseline (BL) and 2-year follow-up (2Y) were included. The cohort was ranked into quartiles by baseline NDI, from lowest/best score (Q1) to highest/worst score (Q4). Means comparison tests analyzed differences between disability groups. Multivariate Analyses (MVA) assessed differences in outcomes of interest controlling for covariates including BL deformity, HRQLs, surgical details and complications.
RESULT(S): A total of 116 patients met inclusion criteria (age: 60.97+/-10.45 yrs, BMI: 28.73+/-7.59kg/m², CCI: 0.94+/-1.31). The cohort presented with mean BL cSVA was 38.54 +/- 19.43mm, TS-CL: 37.34 +/- 19.73, and mJOA: 13.62 +/- 2.71. Surgically, patients had an average of 8.44 +/- 3.41 levels fused, with 53.5% of patients undergoing decompression and 48.3% undergoing osteotomy. Mean BL NDI and numerical rating scale (NRS) of the cohort were 48.33 +/- 17.99 and 6.74 +/- 2.48 respectively. Mean BL NDI by disability group was as follows: Q1: 25.04 +/- 8.19, Q2: 41.61 +/- 2.77, Q3: 53.31 +/- 4.32, and Q4: 69.52 +/- 8.35. MVA assessing improvement in NRS neck and NRS back, found significant differences between disability groups (both p=.007). Patients in Q2 demonstrated the greatest improvement in NRS neck at 2 years (-3.93), which was greater than those in Q3 (-1.61, p=.032) and Q4 (-1.41, p=.015). Patients in Q2 demonstrated greater improvement in NRS back at 2 years (-1.71), compared to those in Q4 (+0.84, p=.010). Rates of MCID in NRS neck were also significantly different across disability groups (p=.023). Patients in Q2 met MCID at the highest rates (69.9%) of all groups, higher than those in Q4 (30.3%), p=.039. MVA found patients in Q2 demonstrated the greatest improvement in EQ5D at 2 years (+0.082), compared to Q1 (+0.073), Q3 (+0.022), and Q4 (+0.014), p=.034. Finally, patients in Q2 demonstrated the greatest improvement in mJOA score from baseline (+1.517), p=.042.
CONCLUSION(S): Patients in Q2, with mean baseline NDI of 42, consistently demonstrated the greatest improvement in HRQLs whereas those in Q4, with mean baseline NDI of 70, saw the least improvement. Thus, baseline NDI between 39 and 44 may represent a disability "wweet spot," within which operative intervention maximizes patient reported outcomes. Furthermore, delaying intervention until patients are severely disabled, beyond an NDI of 61, limits benefits of surgical correction in cervical deformity patients. FDA DEVICE/DRUG STATUS: This abstract does not discuss or include any applicable devices or drugs.
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OBJECTIVE:Revision surgery is often necessary for adult spinal deformity (ASD) patients. Satisfaction with management is an important component of health-related quality of life. The authors hypothesized that patients who underwent multiple revision surgeries following ASD correction would exhibit lower self-reported satisfaction scores. METHODS:This was a retrospective cohort study of 668 patients who underwent ASD surgery and were eligible for a minimum 2-year follow-up. Visits were stratified by occurrence prior to the index surgery (period 0), after the index surgery only (period 1), after the first revision only (period 2), and after the second revision only (period 3). Patients were further stratified by prior spine surgery before their index surgery. Scoliosis Research Society-22 (SRS-22r) health-related quality-of-life satisfaction subscore and total satisfaction scores were evaluated at all periods using multiple linear regression and adjustment for age, sex, and Charlson Comorbidity Index. RESULTS:In total, 46.6% of the study patients had undergone prior spine surgery before their index surgery. The overall revision rate was 21.3%. Among patients with no spine surgery prior to the index surgery, SRS-22r satisfaction scores increased from period 0 to 1 (from 2.8 to 4.3, p < 0.0001), decreased after one revision from period 1 to 2 (4.3 to 3.9, p = 0.0004), and decreased further after a second revision from period 2 to 3 (3.9 to 3.3, p = 0.0437). Among patients with spine surgery prior to the index procedure, SRS-22r satisfaction increased from period 0 to 1 (2.8 to 4.2, p < 0.0001) and decreased from period 1 to 2 (4.2 to 3.8, p = 0.0011). No differences in follow-up time from last surgery were observed (all p > 0.3). Among patients with multiple revisions, 40% experienced rod fracture, 40% proximal junctional kyphosis, and 33% pseudarthrosis. CONCLUSIONS:Among patients undergoing ASD surgery, revision surgery is associated with decreased satisfaction, and multiple revisions are associated with additive detriment to satisfaction among patients initially undergoing primary surgery. These findings have direct implications for preoperative patient counseling and establishment of postoperative expectations.

STUDY DESIGN/METHODS:A retrospective review of operative patients at a single institution. OBJECTIVE:To validate a novel method of detecting pseudarthrosis on dynamic radiographs. SUMMARY OF BACKGROUND DATA/BACKGROUND:A common complication after anterior cervical discectomy and fusion is pseudarthrosis. A previously published method for detecting pseudarthrosis identifies a 1 mm difference in interspinous motion (ISM), which requires calibration of images and relies on anatomic landmarks difficult to visualize. An alternative is to use angles between spinous processes, which does not require calibration and relies on more visible landmarks. METHODS:ISM was measured on dynamic radiographs using the previously published linear method and new angular method. Angles were defined by lines from screw heads to dorsal points of spinous processes. Angular cutoff for fusion was calculated using a regression equation correlating linear and angular measures, based on the 1 mm linear cutoff. Pseudarthrosis was assessed with both cutoffs. Sensitivity, specificity, inter- and intra-reliability of angular and linear measures used post-operative CT as the reference. RESULTS:242 fused levels (81 allograft, 84 PEEK, 40 titanium, 37 standalone cages) were measured in 143 patients (mean age 52.0±11.5, 42%F). 36 patients (66 levels) had 1-year postoperative CTs; 13 patients (13 levels) had confirmed pseudarthrosis. Linear and angular measurements closely correlated (R=0.872), with 2.3° corresponding to 1 mm linear ISM. Potential pseudarthroses was found in 28.0% and 18.5% levels using linear and angular cutoffs, respectively. Linear cutoff had 85% sensitivity, 87% specificity; angular cutoff had 85% sensitivity, 96% specificity for detecting CT-validated pseudarthrosis. Interclass correlation coefficients were 0.974 and 0.986 (both P<0.001); intra-rater reliability averaged 0.953 and 0.974 (P<0.001 for all) for linear and angular methods, respectively. CONCLUSIONS:The angular measure for assessing potential pseudarthrosis is as sensitive as and more specific than published linear methods, has high inter-observer reliability, and can be used without image calibration.

OBJECTIVE:Adult cervical deformity (ACD) has high complication rates due to surgical complexity and patient frailty. Very few studies have focused on longer-term outcomes of operative ACD treatment. The objective of this study was to assess minimum 2-year outcomes and complications of ACD surgery. METHODS:A multicenter, prospective observational study was performed at 13 centers across the United States to evaluate surgical outcomes for ACD. Demographics, complications, radiographic parameters, and patient-reported outcome measures (PROMs; Neck Disability Index, modified Japanese Orthopaedic Association, EuroQol-5D [EQ-5D], and numeric rating scale [NRS] for neck and back pain) were evaluated, and analyses focused on patients with ≥ 2-year follow-up. RESULTS:Of 169 patients with ACD who were eligible for the study, 102 (60.4%) had a minimum 2-year follow-up (mean 3.4 years, range 2-8.1 years). The mean age at surgery was 62 years (SD 11 years). Surgical approaches included anterior-only (22.8%), posterior-only (39.6%), and combined (37.6%). PROMs significantly improved from baseline to last follow-up, including Neck Disability Index (from 47.3 to 33.0) and modified Japanese Orthopaedic Association score (from 12.0 to 12.8; for patients with baseline score ≤ 14), neck pain NRS (from 6.8 to 3.8), back pain NRS (from 5.5 to 4.8), EQ-5D score (from 0.74 to 0.78), and EQ-5D visual analog scale score (from 59.5 to 66.6) (all p ≤ 0.04). More than half of the patients (n = 58, 56.9%) had at least one complication, with the most common complications including dysphagia, distal junctional kyphosis, instrumentation failure, and cardiopulmonary events. The patients who did not achieve 2-year follow-up (n = 67) were similar to study patients based on baseline demographics, comorbidities, and PROMs. Over the course of follow-up, 23 of the total 169 enrolled patients were reported to have died. Notably, these represent all-cause mortalities during the course of follow-up. CONCLUSIONS:This multicenter, prospective analysis demonstrates that operative treatment for ACD provides significant improvement of health-related quality of life at a mean 3.4-year follow-up, despite high complication rates and a high rate of all-cause mortality that is reflective of the overall frailty of this patient population. To the authors' knowledge, this study represents the largest and most comprehensive prospective effort to date designed to assess the intermediate-term outcomes and complications of operative treatment for ACD.