Faculty Bibliography

BACKGROUND:Despite reports showing positive long-term functional outcomes following adult spinal deformity (ASD)-corrective surgery, it is unclear which factors affect the durability of these outcomes. OBJECTIVE:To assess durability of functional gains following ASD-corrective surgery; determine predictors for postoperative loss of functionality. METHODS:Surgical ASD patients > 18 yr with 3-yr Oswestry Disability Index (ODI) follow-up, and 1-yr postoperative (1Y) ODI scores reaching substantial clinical benefit (SCB) threshold (SCB < 31.3 points). Patients were grouped: those sustaining ODI at SCB threshold beyond 1Y (sustained functionality) and those not (functional decline). Kaplan-Meier survival analysis determined postoperative durability of functionality. Multivariate Cox regression assessed the relationship between patient/surgical factors and functional decline, accounting for age, sex, and levels fused. RESULTS:All 166 included patients showed baseline to 1Y functional improvement (mean ODI: 35.3 ± 16.5-13.6 ± 9.2, P < .001). Durability of satisfactory functional outcomes following the 1Y postoperative interval was 88.6% at 2-yr postoperative, and 71.1% at 3-yr postoperative (3Y). Those sustaining functionality after 1Y had lower baseline C2-S1 sagittal vertical axis (SVA) and T1 slope (both P < .05), and lower 1Y thoracic kyphosis (P = .035). From 1Y to 3Y, patients who sustained functionality showed smaller changes in alignment: pelvic incidence minus lumbar lordosis, SVA, T1 slope minus cervical lordosis, and C2-C7 SVA (all P < .05). Those sustaining functionality beyond 1Y were also younger, less frail at 1Y, and had lower rates of baseline osteoporosis, hypertension, and lung disease (all P < .05). Lung disease (Hazard Ratio:4.8 [1.4-16.4]), 1Y frailty (HR:1.4 [1.1-1.9]), and posterior approach (HR:2.6 [1.2-5.8]) were associated with more rapid decline. CONCLUSION/CONCLUSIONS:Seventy-one percent of ASD patients maintained satisfactory functional outcomes by 3Y. Of those who failed to sustain functionality, the largest functional decline occurred 3-yr postoperatively. Frailty, preoperative comorbidities, and surgical approach affected durability of functional gains following surgery.

PURPOSE/OBJECTIVE:To assess preliminary associations between fatty-infiltration (FI) of cervical spine extensor musculature, cervical sagittal balance, and clinical outcomes in cervical deformity (CD) patients. METHODS:Operative CD patients (C2-C7 Cobb > 10°, CL > 10°, cSVA > 4 cm, or CBVA > 25°) with pre-operative (BL) MRIs and 1-year (1Y) post-operative MRIs or CTs were assessed for fatty-infiltration of cervical extensor musculature, using dedicated imaging software at each C2-C7 intervertebral level and the apex of deformity (apex). FI was gauged as a ratio of fat-free-muscle-cross-sectional-area (FCSA) over total-muscle-CSA (TCSA), with lower ratio values indicating greater FI. BL-1Y associations between FI, sagittal alignment, and clinical outcomes were assessed using appropriate parametric and non-parametric tests. RESULTS:: 0.551, p = 0.014). CONCLUSIONS:Deformity correction and sagittal balance appear to influence the reestablishment of cervical muscle tone from C2-C7 and reduction of back pain for severely frail CD patients. This analysis helps to understand cervical extensor musculature's role amongst CD patients.

Metabolic syndrome is a clustering of clinical findings defined in the literature including hypertension, high glucose, abdominal obesity, high triglyceride, and low high-density lipoprotein cholesterol levels. The purpose of this study was to assess perioperative outcomes in patients undergoing spine fusion surgery with (MetS) and without (no-MetS) a history of metabolic syndrome. Included: Patients ≥18 yrs old undergoing spine fusion procedures diagnosed with MetS components with BL and 1-year follow-up were isolated in a single-center database. Patients in the two groups were propensity score matched for levels fused. 250 spine fusion patients (58 yrs, 52.2%F, 39.0 kg/m²) with an average CCI of 1.92 were analyzed. 125 patients were classified with MetS (60.2 yrs, 52%F, CCI: 3.2). MetS patients were significantly older (p = 0.012). MetS patients underwent significantly more open (Met-S: 78.4% vs No-MetS: 45.6%, p < 0.001) and posterior approached procedures (Met-S: 60.8% vs No-MetS: 47.2%, p = 0.031). Mean operative time: 272.4 ± 150 min (MetS: 288.1 min vs. no-MetS: 259.7; p = 0.089). Average length of stay: 4.6 days (MetS: 5.27 vs no-MetS: 3.95; p = 0.095). MetS patients had more post-operative complications (29.6% vs. 18.4%; p = 0.038), specifically neuro (6.4% vs 2.4%), pulmonary (4% vs. 1.6%), and urinary (4.8% vs 2.4%) complications. Binary logistic regression analyses found that MetS was an independent risk factor for post-operative complications (OR: 1.865 [1.030-3.375], p = 0.040). With longer surgeries and greater open-exposure types, MetS patients were at greater risk for complications, despite controlling for total number of levels fused. Surgeons should be aware of the increased threat to spine surgery patients with metabolic syndrome in order to optimize surgical decision-making.

BACKGROUND CONTEXT/BACKGROUND:Obesity has risen to epidemic proportions within the United States. As the rates of obesity have increased, so has its prevalence among patients undergoing adult spinal deformity (ASD) surgery. The effect of obesity on the cost efficiency of corrective procedures for ASD has not been effectively evaluated. PURPOSE/OBJECTIVE:To investigate differences in cost efficiency of ASD surgery for patients stratified by body mass index (BMI). STUDY DESIGN/SETTING/METHODS:Retrospective review of a single center ASD database. PATIENT SAMPLE/METHODS:505 ASD patients OUTCOME MEASURES: Complications, revisions, costs, EuroQol-5D (EQ5D), quality adjusted life years (QALYS), cost per QALY. METHODS:ASD patients (scoliosis≥20°, SVA≥5cm, PT≥25°, or TK ≥60°) ≥18, undergoing ≥4 level fusions were included. Patients were stratified into NIH-defined obesity groups based on their preoperative BMI: underweight 18.5< (U), normal 18.5-24.9 (N), overweight 25.0-29.9 (O), obese I 30.0-34.9 (OI), obese II 35.0-39.9 (OII), and obesity class III 40.0 + (OIII). Total surgery costs for each ASD obesity group were calculated. Costs were calculated using the PearlDiver database, which reflects both private insurance and Medicare reimbursement claims. Overall complications (CC) and major complications (MCC) were assessed according to CMS. DEFINITIONS/BACKGROUND:QALYs and cost per QALY for obesity groups were calculated using an annual 3% discount up to life expectancy (78.7 years). RESULTS:In all, 505 patients met inclusion criteria. Baseline demographics and surgical details were: age 60.8 ± 14.8, 67.6% female, BMI 28.8 ± 7.30, 81.0% posterior approach, 18% combined approach, 10.1 ± 4.2 levels fused, op time 441.2 ± 146.1 minutes, EBL 1903.8 ± 1594.7 cc, LOS 8.7 ± 10.7 days. There were 17 U, 154 N patients, 151 O patients, 100 OI, 51 OII, and 32 OIII patients. Revision rates by obesity group were: 0% U, 3% N patients, 3% O patients, 5% OI, 4% OII, and 6% for OIII patients. The total surgery costs by obesity group were: $48,757.86 U, $49,688.52 N, $47,219.93 O, $50,467.66 OI, $51,189.47 OII, and $53,855.79 OIII. In an analysis of patients with baseline and 1Y EQ5D follow up, the cost per QALY by obesity group was: $153,737.78 U, $229,222.37 N, $290,361.68 O, $493,588.47 OI, $327,876.21 OII, and $171,680.00 OIII. If that benefit was sustained to life expectancy, the cost per QALY was $8,588.70 U, $12,805.72 N, $16,221.32 O, $27,574.77 OI, $18,317.11 OII, and $9,591.06 for OIII. CONCLUSIONS:Among adult spinal deformity patients, those with BMIs in the obesity I, obesity II, or obesity class III range had more expensive total surgery costs. When assessing 1 year cost per quality adjusted life year, obese patients had costs 32% higher than non-obese patients ($224,440.61 vs. $331,048.23). Further research is warranted on the utility of optimizing modifiable preoperative health factors for patients undergoing corrective adult spinal deformity surgery.

OBJECTIVE:Investigate the differences in spine surgery cost for metabolic syndrome patients. METHODS:Included: Patients ≥18, undergoing fusion. Patients were divided into cervical, thoracic, and lumbar groups based on their upper instrumented vertebrae (UIV). Metabolic syndrome patients (MetS) included: BMI >30, DM, dyslipidemia, and HTN. Propensity score matching for invasiveness between Non-MetS and MetS used to assess cost differences. Total surgery costs for MetS and non-MetS ASD patients were compared. QALYs and cost per QALY for UIV groups were calculated. RESULTS:312 invasiveness matched surgeries met inclusion criteria. Baseline demographics and surgical details: age 57.7 ± 14.5, 54% female, BMI 31.1 ± 6.6, 17% anterior approach, 70% posterior approach, 13% combined approach, 3.8 ± 4.1 levels fused. The average costs of surgery between MetS and non-Mets patients was $60,579.30 vs. $52,053.23 (p<0.05). When costs were compared between UIV groups, MetS patients had higher cervical and thoracic surgery costs ($23,203.43 vs $19,153.43, $75,230.05 vs. $65,746.16, all p<0.05) and lower lumbar costs ($31,775.64 vs. $42,643.37, p<0.05). However, the average cost per QALY at 1Y was $639,069.32 for MetS patients and $425,840.30 for non-Mets patients (p<0.05). At life expectancy, the cost per QALY was $45,456.83 vs. $26,026.84 (p<0.05). CONCLUSIONS:When matched by invasiveness, metabolic syndrome patients had an average 16.4% higher surgery costs, 50% higher costs per quality adjusted life years at 1 year, and 75% higher cost per quality adjusted life years at life expectancy. Further research is needed on the possible utility of reducing comorbidities in preoperative patients.

BACKGROUND:Distal junctional kyphosis (DJK) development after cervical deformity (CD)-corrective surgery is a growing concern for surgeons and patients. Few studies have investigated risk factors that predict the occurrence of DJK. OBJECTIVE:To predict DJK development after CD surgery using predictive modeling. METHODS:CD criteria was at least one of the following: C2-C7 Coronal/Cobb > 10°, C2-7 sagittal vertical axis (cSVA) > 4 cm, chin-brow vertical angle > 25°. DJK was defined as the development of an angle <-10° from the end of fusion construct to the second distal vertebra, and change in this angle by <-10° from baseline to postoperative. Baseline demographic, clinical, and surgical information were used to predict the occurrence of DJK using generalized linear modeling both as one overall model and as submodels using baseline demographic and clinical predictors or surgical predictors. RESULTS:One hundred seventeen CD patients were included. At any postoperative visit up to 1 yr, 23.1% of CD patients developed DJK. DJK was predicted with high accuracy using a combination of baseline demographic, clinical, and surgical factors by the following factors: preoperative neurological deficit, use of transition rod, C2-C7 lordosis (CL)<-12°, T1 slope minus CL > 31°, and cSVA > 54 mm. In the model using only baseline demographic/clinical predictors of DJK, presence of comorbidities, presence of baseline neurological deficit, and high preoperative C2-T3 angle were included in the final model (area under the curve = 87%). The final model using only surgical predictors for DJK included combined approach, posterior upper instrumented vertebrae below C4, use of transition rod, lack of anterior corpectomy, more than 3 posterior osteotomies, and performance of a 3-column osteotomy. CONCLUSION/CONCLUSIONS:Preoperative assessment and consideration should be given to these factors that are predictive of DJK to mitigate poor outcomes.

INTRODUCTION/BACKGROUND:Outcomes after anterior cervical diskectomy and fusion (ACDF) and cervical total disk arthroplasty (TDA) are satisfactory, but related morbidity and revision surgery rates are notable. This study sought to determine complication variations among ACDF, TDA, and combined ACDF-TDA as well as predictors of postoperative complications. METHODS:Patients undergoing 1- to 2-level ACDF and/or TDA with at least a 2-year follow-up from 2009 to 2011 were identified from the Statewide Planning and Research Cooperative System database. Patient demographics, hospital-related parameters, mortality, and postoperative outcomes were compared, and their predictors were identified using multivariate logistic regression. RESULTS:A total of 16,510 and 449 individuals underwent ACDF and cervical TDA, respectively, and 201 underwent ACDF-TDA. ACDF-TDA patients had the highest rates of cardiac complications and pulmonary embolism (PE) (P ≤ 0.006), whereas TDA patients had higher individual surgical and device/implant/internal fixation complications (P ≤ 0.025). ACDF-TDA patients experienced the lowest rate of revisions. Cervical TDA increased the odds of any surgical complications (OR = 2.5, P = 0.002), overall complications (OR = 1.57, P = 0.034), and revisions (OR = 2.29, P < 0.001). Deyo index predicted any medical/surgical complications (OR = 1.43 and 1.19, respectively). Female sex was associated with increased odds of readmission (OR 1.30, P < 0.001) but was protective against medical complications (OR = 0.81, P = 0.013). DISCUSSION/CONCLUSIONS:Combined ACDF-TDA procedures were not associated with increases in 2-year individual or overall complications, readmissions, or revisions. LEVEL OF EVIDENCE/METHODS:Level 3-Therapeutic study.

BACKGROUND:Frailty is a relatively new area of study for patients with cervical deformity (CD). As of yet, little is known of how operative intervention influences frailty status for patients with CD. OBJECTIVE:To investigate drivers of postoperative frailty score and variables within the cervical deformity frailty index (CD-FI) algorithm that have the greatest capacity for change following surgery. METHODS:Descriptive analysis of the cohort were performed, paired t-tests determined significant baseline to 1 yr improvements of factors comprising the CD-FI. Pearson bivariate correlations identified significant associations between postoperative changes in overall CD-FI score and CD-FI score components. Linear regression models determined the effect of successful surgical intervention on change in frailty score. RESULTS:A total of 138 patients were included with baseline frailty scores of 0.44. Following surgery, mean 1-yr frailty score was 0.27. Of the CD-FI variables, 13/40 (32.5%) were able to improve with surgery. Frailty improvement was found to significantly correlate with baseline to 1-yr change in CBV, PI-LL, PT, and SVA C7-S1. HRQL CD-FI components reading, feeling tired, feeling exhausted, and driving were the greatest drivers of change in frailty. Linear regression analysis determined successful surgical intervention and feeling exhausted to be the greatest significant predictors of postoperative change in overall frailty score. CONCLUSION/CONCLUSIONS:Complications, correction of sagittal alignment, and improving a patient's ability to read, drive, and chronic exhaustion can significantly influence postoperative frailty. This analysis is a step towards a greater understanding of the relationship between disability, frailty, and surgery in CD.

BACKGROUND CONTEXT/BACKGROUND:Lateral lumbar interbody fusion is a popular technique used in spine surgery. It is minimally invasive, provides indirect decompression, and allows for coronal plane deformity correction. Despite these benefits, the approach to lateral lumbar interbody fusion has been linked to complications associated with the lumbosacral plexus and vascular anatomy. As a result, vascular surgeons may be recruited for the exposure portion of the procedure. PURPOSE/OBJECTIVE:The purpose of this study was to compare exposure related complication and post-operative (postop) neuropraxia rates between exposure (EXP) and spine surgeon only (SSO) groups when performing the approach for lateral lumbar interbody fusion (LLIF). STUDY DESIGN/SETTING/METHODS:Retrospective analysis of patients treated at a single institution PATIENT SAMPLE: Patients undergoing LLIF procedures between 2012-2018 OUTCOME MEASURES: Operative time, estimated blood loss, fluoroscopy, length of stay, intra- and post-operative complications, and physiologic measures including pre- and post-operative motor examinations and unresolved neuropraxia METHODS: Patients who underwent LLIF were separated into EXP and SSO groups based on the presence or absence of vascular/general surgeon during the approach. The entire clinical history of patients with a decrease in pre and postop motor examination were reviewed for the presence of neuropraxia. All other intra- and postop exposure related complications were recorded for comparison. PSM was performed to account for age, Charlston Comorbity Index (CCI) % LLIFs including L4-L5, and number levels fused. Independent T-test and Chi-squared analyses were used to identify significant differences between EXP and SSO groups. Statistical significance was set at p<0.05. RESULTS:Two hundred seventy-five patients underwent LLIF procedures, 155 SSO and 120 EXP. Post-operatively, 26 patients (11.1%) experienced a drop in any MRC score, and two patients (0.7%) experience unresolved quadriceps palsies. The mean recovery time for MRC scores was 84.4 days. Other complications included 2 pneumothoraces (0.7%), 1 iliac vein injury (0.4%), 14 cases of ileus (5.1%), 3 pulmonary emboli (1.1%), 2 deep vein thrombosis (0.7%), 3 cases of abdominal wall paresis (1.1%), and one abdominal hematoma (0.4%). After PSM, demographics including age, gender, BMI, CCI, levels fused and operative time were similar between cohorts. Twenty patients had changes in pre- to postop motor scores (SSO 9.4%, EXP 12.4%, p>0.05). Iliopsoas motor scores decreased at the highest rate (EXP 12.4%, 8.2% SSO, p>0.05) followed by quadriceps (EXP 5.2%, SSO 4.7%, p>0.05). One SSO patient's postop course was complicated by a foot drop but returned to baseline within 1-year. One patient in EXP group developed an unresolved quadriceps palsy (EXP 1.0%, SSO 0.0% p>0.05). Intra-op exposure complications included one pneumothorax (EXP 1.0%, SSO 0.0%, p>0.05). There were no differences in PE/DVT, Ileus, or LOS. In the EXP cohort, three patients experienced abdominal wall paresis (EXP 2.9%, SSO 0.00%, p=0.246). CONCLUSIONS:Comparing the LLIF exposures performed by EXP and SSO, we found no significant difference in the rates of complications. Additional research is needed to determine the etiology of the abdominal wall complications. In conclusion, neuropraxia- and approach-related complications are similarly low between exposure and spine surgeons.

STUDY DESIGN/METHODS:Retrospective review of a prospective database. OBJECTIVE:The aim of this study was to evaluate postop clinical recovery among adult spinal deformity (ASD) patients between frailty states undergoing primary procedures SUMMARY OF BACKGROUND DATA.: Frailty severity may be an important determinant for impaired recovery after corrective surgery. METHODS:It included ASD patients with health-related quality of life (HRQLs) at baseline (BL), 1 year (1Y), and 3 years (3Y). Patients stratified by frailty by ASD-frailty index scale 0-1(no frailty: <0.3 [NF], mild: 0.3-0.5 [MF], severe: >0.5 [SF]). Demographics, alignment, and SRS-Schwab modifiers were assessed with χ/paired t tests to compare HRQLs: Scoliosis Research Society 22-question Questionnaire (SRS-22), Numeric Rating Scale (NRS) Back/Leg Pain, Oswestry Disability Index (ODI). Area-under-the-curve (AUC) method generated normalized HRQL scores at baseline (BL) and f/u intervals (1Y, 3Y). AUC was calculated for each f/u, and total area was divided by cumulative f/u, generating one number describing recovery (Integrated Health State [IHS]). RESULTS:A total of 191 patients were included (59 years, 80% females). By frailty: 43.6% NF, 40.8% MF, 15.6% SF. SF patients were older (P = 0.003), >body mass index (P = 0.002). MF and SF were significantly (P < 0.001) more malaligned at BL: pelvic tilt (NF: 21.6°; MF: 27.3°; SF: 22.1°), pelvic incidence and lumbar lordosis (7.4°, 21.2°, 19.7°), sagittal vertical axis (31 mm, 87 mm, 82 mm). By SRS-Schwab, NF were mostly minor (40%), and MF and SF markedly deformed (64%, 57%). Frailty groups exhibited BL to 3Y improvement in SRS-22, ODI, NRS Back/Leg (P < 0.001). After HRQL normalization, SF had improvement in SRS-22 at year 1 and year 3 (P < 0.001), and NRS Back at 1Y. 3Y IHS showed a significant difference in SRS-22 (NF: 1.2 vs. MF: 1.32 vs. SF: 1.69, P < 0.001) and NRS Back Pain (NF: 0.52, MF: 0.66, SF: 0.6, P = 0.025) between frailty groups. SF had more complications (79%). SF/marked deformity had larger invasiveness score (112) compared to MF/moderate deformity (86.2). Controlling for baseline deformity and invasiveness, SF showed more improvement in SRS-22 IHS (NF: 1.21, MF: 1.32, SF: 1.66, P < 0.001). CONCLUSION/CONCLUSIONS:Although all frailty groups exhibited improved postop disability/pain scores, SF patients recovered better in SRS-22 and NRS Back. Despite SF patients having more complications and larger invasiveness scores, they had overall better patient-reported outcomes, signifying that with frailty severity, patients have more room for improvement postop compared to BL quality of life. LEVEL OF EVIDENCE/METHODS:3.