Faculty Bibliography

BACKGROUND CONTEXT/BACKGROUND:Adjacent segment disease (ASD) is a potential complication following lumbar spinal fusion. PURPOSE/OBJECTIVE:This study aimed to demonstrate the demographic, clinical, and operative risk factors associated with ASD development following lumbar fusion. STUDY DESIGN/SETTING/METHODS:Systematic review and meta-analysis. PATIENT SAMPLE/METHODS:We identified 35 studies that reported risk factors for ASD, with a total number of 7,374 patients who had lumbar spine fusion. OUTCOME MEASURES/METHODS:We investigated the demographic, clinical, and operative risk factors for ASD after lumbar fusion. METHODS:A literature search was done using PubMed, Embase, Medline, Scopus, and the Cochrane library databases from inception to December 2019. The methodological index for non-randomized studies (MINORS) criteria was used to assess the methodological quality of the included studies. A meta-analysis was done to calculate the odds ratio (OR) with the 95% confidence interval (CI) for dichotomous data and mean difference (MD) with 95% CI for continuous data. RESULTS:; 95% confidence interval [CI]=1.49-2.45; p<.001), floating fusion (Odds ratio [OR]=1.78; 95% CI=1.32-2.41; p<.001), superior facet joint violation (OR=10.43; 95% CI=6.4-17.01; p<.001), and decompression outside fusion construct (OR=1.72; 95% CI=1.25-2.37; p<.001). CONCLUSIONS:The overall level of evidence was low to very low. Higher preoperative BMI, floating fusion, superior facet joint violation, and decompression outside fusion construct are significant risk factors of development of ASD following lumbar fusion surgeries.

BACKGROUND CONTEXT:The concept of frailty has become increasingly recognized, and while patients with cancer are at increased risk for frailty, its influence on perioperative outcomes in metastatic spine tumors is uncertain. Furthermore, the impact of frailty can be confounded by comorbidities or metastatic disease burden. PURPOSE:The purpose of this study was to evaluate the influence of frailty and comorbidities on adverse outcomes in the surgical management of metastatic spine disease. STUDY DESIGN/SETTING:Retrospective analysis of a nationwide database to include patients undergoing spinal fusion for metastatic spine disease. PATIENT SAMPLE:A total of 1,974 frail patients who received spinal fusion with spinal metastasis, and 1,975 propensity score matched non-frail patients. OUTCOME MEASURES:Outcomes analyzed included mortality, complications, length of stay (LOS), nonroutine discharges and costs. METHODS:A validated binary frailty index (Johns Hopkins Adjusted Clinical Groups) was used to identify frail and non-frail groups, and propensity score-matched analysis (including demographics, comorbidities, surgical and tumor characteristics) was performed. Sub-group analysis of levels involved was performed for cervical, thoracic, lumbar and junctional spine. Multivariable-regression techniques were used to develop predictive models for outcomes using frailty and the Elixhauser Comorbidity Index (ECI). RESULTS:7,772 patients underwent spinal fusion with spinal metastasis, of which 1,974 (25.4%) patients were identified as frail. Following propensity score matching for frail (n=1,974) and not-frail (n=1,975) groups, frailty demonstrated significantly greater medical complications (OR=1.58; 95% CI 1.33-1.86), surgical complications (OR=1.46; 95% CI 1.15-1.85), LOS (OR=2.65; 95% CI 2.09-3.37), nonroutine discharges (OR=1.79; 95% CI 1.46-2.20) and costs (OR=1.68; 95% CI 1.32-2.14). Differences in mortality were only observed in subgroup analysis and were greater in frail junctional and lumbar spine subgroups. Models using ECI alone (AUC=0.636-0.788) demonstrated greater predictive ability compared to those using frailty alone (AUC=0.633-0.752). However, frailty combined with ECI improved the prediction of increased LOS (AUC=0.811), cost (AUC=0.768), medical complications (AUC=0.723) and nonroutine discharges (AUC=0.718). Predictive modeling of frailty in subgroups demonstrated the greatest performance for mortality (AUC=0.750) in the lumbar spine, otherwise performed similarly for LOS, costs, complications, and discharge across subgroups. CONCLUSIONS:A high prevalence of frailty existed in the current patient cohort. Frailty contributed to worse short-term adverse outcomes and could be more influential in the lumbar and junctional spine due to higher risk of deconditioning in the postoperative period. Predictions for short term outcomes can be improved by adding frailty to comorbidity indices, suggesting a more comprehensive preoperative risk stratification should include frailty.

PURPOSE:Two main surgical approaches are available for fusing the sacroiliac joint (SIJ): an open or minimally invasive (MIS) approach. The purpose of this study was to analyze the associated total hospital charges and postoperative complications of the MIS and open approach. METHODS:Using the 2016 and 2017 National Readmission Database, we conducted a retrospective cohort analysis of 2521 patients who received a SIJ fusion with an open (N = 1990) or MIS (N = 531) approach for diagnosed sacrum pain, sacroiliitis, sacral instability, or spondylosis. Each cohort was analyzed for postoperative complications. RESULTS:We identified 604 patients diagnosed with sacrum pain, 1142 with sacroiliitis, 315 with spondylosis, and 288 with sacral instability. Patients who received the open approach for sacrum pain had significantly higher rates of novel post-procedural pain (p = 0.045) and novel lumbar pathology (p = 0.015) within 30 days. On 30-day follow-up, patients with sacroiliitis treated with open SIJ fusion had significantly higher rates of novel postprocedural pain compared to those treated with MIS fusion (p = 0.045). Patients who received the open approach for spondylosis resulted in significantly higher rates of non-elective readmission within 30 days compared to the MIS approach (p < 0.0001). In addition, the open technique for spondylosis resulted in significantly higher rates of non-elective readmissions for infection within 30 days (p = 0.014). On 30-day follow-up, patients with sacral instability treated with open SIJ fusion had significantly higher rates of UTI (p = 0.045). CONCLUSION:Our study suggests that there exist unique postoperative complications that arise after SIJ fusion specific to preoperative diagnosis and surgical approach.

PURPOSE:Anterior thoracolumbar (TL) surgical approaches provide more direct trajectories compared to posterior approaches. Proper patient selection is key in identifying populations that may benefit from anterior TL fusion. Here, we utilize predictive analytics to identify risk factors in anterior TL fusion in patients with trauma and deformity. METHODS:In this retrospective cohort study of patients receiving anterior TL fusion (between and including T12/L1), population-based regression models were developed to identify risk factors using the National Readmission Database 2016-2017. Readmissions were analyzed at 30- and 90-day intervals. Risk factors included hypertension, obesity, malnutrition, smoking, alcohol use, long-term opioid use, and frailty. Multivariate regression models were developed to determine the influence of each risk factor on complication rates. RESULTS:A total of 265 and 375 patients were identified for the scoliosis and burst fracture cohorts, respectively. In patients with scoliosis, alcohol use was found to increase the length of stay (LOS) (p = 0.00061) and all-payer inpatient cost following surgery (p = 0.014), and frailty was found to increase the inpatient LOS (p = 0.0045). In patients with burst fractures, malnutrition was found to increase the LOS (p < 0.0001) and all-payer cost (p < 0.0001), obesity was found to increase the all-payer cost (p = 0.012), and frailty was found to increase the all-payer cost (p = 0.031) and LOS (p < 0.0001). DISCUSSION:Patient-specific risk factors in anterior TL fusion surgery significantly influence complication rates. An understanding of relevant risk factors before surgery may facilitate preoperative patient selection and postoperative patient triage and risk categorization.

STUDY DESIGN:This study was a retrospective cohort database study which looked at the relationship between myocardial reinfarction following lumbar spine surgery. OBJECTIVE:Current study aimed to determine the risk of reinfarction associated with the time between initial myocardial infarction (MI) and lumbar spine surgery, type of lumbar surgical procedure, and other risk factors. SUMMARY OF BACKGROUND INFO:Several studies have demonstrated a strong temporal pattern between postoperative reinfarction rate and the period between previous MI and surgery. To the best of our knowledge, no study has looked specifically at the temporal relationship between previous MI, lumbar spine surgery and incidence of postoperative myocardial reinfarction. MATERIALS AND METHODS:The Humana database was analyzed from Q1 2007 through Q3 2016 and the Medicare database was analyzed from Q1 2005 through Q4 2014. Patients were placed into 1 of 5 groups based on time between MI and surgery: 0-3, 4-6, 7-12, 13-24, and 25+ months. Reinfarction rates were determined in these groups. Age, sex, and type of surgery were analyzed to determine association with postoperative reinfarction rates. RESULTS:There was a strong correlation between postoperative myocardial reinfarction and lumbar spine surgery occurring 0-3 months after the patient's initial MI (P<0.01). Those patients had a risk ratio >3 (P<0.01) compared with patients who underwent lumbar spine surgery after an interval >3 months between initial MI and lumbar spine surgery. In addition, spinal fusion procedures were associated with a greater risk of postoperative myocardial reinfarction than nonfusion procedures. CONCLUSION:In both databases, there was a clinically relevant and statistically significant increase in myocardial reinfarction in patients who experienced an MI 0-3 months before lumbar spine surgery. We believe that the current study helps in treatment planning for patients with a history of MI who are considering spine surgery. LEVEL OF EVIDENCE:Level III.

Growth of long bones and vertebrae is maintained postnatally by a long-lasting pool of progenitor cells. Little is known about the molecular mechanisms that regulate the output and maintenance of the cells that give rise to mature cartilage. Here we demonstrate that postnatal chondrocyte-specific deletion of a transcription factor Stat3 results in severely reduced proliferation coupled with increased hypertrophy, growth plate fusion, stunting and signs of progressive dysfunction of the articular cartilage. This effect is dimorphic, with females more strongly affected than males. Chondrocyte-specific deletion of the IL-6 family cytokine receptor gp130, which activates Stat3, phenocopied Stat3-deletion; deletion of Lifr, one of many co-receptors that signals through gp130, resulted in a milder phenotype. These data define a molecular circuit that regulates chondrogenic cell maintenance and output and reveals a pivotal positive function of IL-6 family cytokines in the skeletal system with direct implications for skeletal development and regeneration.

PURPOSE:This study evaluates the influence of patient frailty status on postoperative complications in those receiving single-level lumbar fusion surgery. METHODS:The nationwide readmission database was retrospectively queried between 2016 and 2017 for all patients receiving single-level lumbar fusion surgery. Readmissions were analyzed at 30, 90, and 180 days from primary discharge. Demographics, frailty status, and relevant complications were queried at index admission and all readmission intervals. Complications of interest included infection, urinary tract infection (UTI), posthemorrhagic anemia, inpatient length of stay (LOS), and adjusted all-payer costs. Nearest-neighbor propensity score matching for demographics was implemented to identify non-frail control patients with similar diagnoses and procedures. The analysis used nonparametric Mann-Whitney U testing and odds ratios. RESULTS:Comparing propensity-matched cohorts revealed significantly greater LOS and total all-payer inpatient costs in frail patients than non-frail patients with comparable demographics and comorbidities (p < 0.0001 for both). Furthermore, frail patients encountered higher rates of UTI (OR: 3.97, 95%CI: 3.21-4.95, p < 0.0001), infection (OR: 6.87, 95%CI: 4.55-10.86, p < 0.0001), and posthemorrhagic anemia (OR: 1.94, 95%CI: 1.71-2.19, p < 0.0001) immediately following surgery. Frail patients had significantly higher rates of 30-day (OR: 1.24, 95%CI: 1.02-1.51, p = 0.035), 90-day (OR: 1.38, 95%CI: 1.17-1.63, p < 0.001), and 180-day (OR: 1.55, 95%CI: 1.30-1.85, p < 0.0001) readmissions. Lastly, frail patients had higher rates of infection at 30-day (OR: 1.61, 95%CI: 1.05-2.46, p = 0.027) and 90-day (OR: 1.51, 95%CI: 1.07-2.16, p = 0.020) readmission intervals. CONCLUSIONS:Patient frailty status may serve as an important predictor of postoperative outcomes in patients receiving single-level lumbar fusion surgery.

STUDY DESIGN:This was a large database study. OBJECTIVE:The objective of this study was to compare the incidence of complications and reoperation rates between the most common surgical treatments for cervical spondylotic myelopathy (CSM): anterior cervical discectomy and fusion (ACDF), anterior cervical corpectomy and fusion (ACCF), and posterior laminectomy and fusion (Lamifusion). SUMMARY OF BACKGROUND DATA:CSM is a major contributor to disability and reduced quality of life worldwide. METHODS:Humana insurance database was queried for CSM diagnoses between 2007 and 2016. The initial population was divided based on the surgical treatment and matched for age, sex, and Charlson Comorbidity index. Specific postoperative complications or revisions were analyzed at individual time points. Pearson χ2 analysis with Yate continuity correction was used. RESULTS:Lamifusion had significantly higher rates of wound infection/disruption than ACDF or ACCF (5.03%, 2.19%, 2.29%; P=0.0008, 0.002, respectively) as well as iatrogenic deformity (4.75%, 2.19%, 2.10%; P=0.0036, 0.0013). Lamifusion also had a significantly higher rate of shock and same-day transfusion than ACDF (4.75%, 2.01%, P=0.0005), circulatory complications (2.01%, <1%, P=0.0183), and C5 palsy (4.84%, 1.74%, P≤0.0001). Compared with ACDF, Lamifusion had higher rates of hardware complication (3.29%, 2.01%, P=0.0468), and revision surgery (8.23% 5.85%, P=0.0395). Lamifusion had significantly lower rates of dysphagia than either ACDF (3.93% vs. 6.58%, P=0.0089) or ACCF (3.93% vs. 8.59%, P<0.0001). When comparing ACCF to ACDF, ACCF had significantly higher rates of circulatory complications (2.38%, <1%, P=0.0053), shock/same-day transfusion (3.2%, 2.0%, P=0.59), C5 palsy (3.47%, 1.74%, P=0.0108), and revision surgery (9.51%, 5.85%, P=0.0086). CONCLUSIONS:The data shows that posterior Lamifusion has higher overall rate of complications compared with ACDF or ACCF. Furthermore, when comparing the anterior approaches, ACDF was associated with lower rate of complication and revision. ACCF had the highest overall rate of revision surgery.

STUDY DESIGN/METHODS:Retrospective cohort study. OBJECTIVE:The aim of this study was to compare different aspects of fusion surgery in patients with osteoporosis with regard to graft subtype and surgical approach. SUMMARY OF BACKGROUND DATA/BACKGROUND:Osteoporosis and chronic lower back pain are common in elderly populations and significantly increase the risk of compression fractures within the spine. METHODS:Using the 2016-2017 National Readmission Database we identified 11,086 osteoporotic patients who received lumbar fusion using ICD-10 coding. Information regarding biologic graft type and surgical approach was collected. Patients were stratified by number of levels fused. Perioperative complications were collected at 30-, 90-, and 180-day follow-up intervals. Statistical analysis included univariate testing and multivariate regression modeling, controlling for patient demographics and comorbidities. RESULTS:Patients receiving single-level fusion with autologous grafts had higher rates of hardware failure (P = 0.00014) at 30-day follow-up and 90-day follow-up (P < 0.0001) and higher rates of lumbar vertebral fractures at 90-day follow-up (P = 0.045) compared to those treated with nonautologous grafts. Patients receiving lumbar fusion with anterior and posterior approaches had no difference in readmission or infection rates, but the anterior approach was associated with a higher cost. CONCLUSION/CONCLUSIONS:In this study, osteoporotic patients treated with autologous grafts had higher rates of complications compared to those treated with nonautologous grafts. Anterior and posterior approaches had similar complication rates; however, the anterior approach was associated with a higher total cost.Level of Evidence: 4.