A perioperative cost analysis comparing single-level minimally invasive and open transforaminal lumbar interbody fusion.

BACKGROUND CONTEXT: Emerging literature suggests superior clinical short- and long-term outcomes of MIS (minimally invasive surgery) TLIFs (transforaminal lumbar interbody fusion) versus open fusions. Few studies to date have analyzed the cost differences between the two techniques and their relationship to acute clinical outcomes. PURPOSE: The purpose of the study was to determine the differences in hospitalization costs and payments for patients treated with primary single-level MIS versus open TLIF. The impact of clinical outcomes and their contribution to financial differences was explored as well. STUDY DESIGN/SETTING: This study was a nonrandomized, nonblinded prospective review. PATIENT SAMPLE: Sixty-six consecutive patients undergoing a single-level TLIF (open/MIS) were analyzed (33 open, 33 MIS). Patients in either cohort (MIS/open) were matched based on race, sex, age, smoking status, medical comorbidities (Charlson Comorbidity index), payer, and diagnosis. Every patient in the study had a diagnosis of either degenerative disc disease or spondylolisthesis and stenosis. OUTCOME MEASURES: Operative time (minutes), length of stay (LOS, days), estimated blood loss (EBL, mL), anesthesia time (minutes), Visual Analog Scale (VAS) scores, and hospital cost/payment amount were assessed. METHODS: The MIS and open TLIF groups were compared based on clinical outcomes measures and hospital cost/payment data using SPSS version 20.0 for statistical analysis. The two groups were compared using bivariate chi-squared analysis. Mann-Whitney tests were used for non-normal distributed data. Effect size estimate was calculated with the Cohen d statistic and the r statistic with a 95% confidence interval. RESULTS: Average surgical time was shorter for the MIS than the open TLIF group (115.8 minutes vs. 186.0 minutes respectively; p=.001). Length of stay was also reduced for the MIS versus the open group (2.3 days vs. 2.9 days, respectively; p=.018). Average anesthesia time and EBL were also lower in the MIS group (p<.001). VAS scores decreased for both groups, although these scores were significantly lower for the MIS group (p<.001). Financial analysis demonstrated lower total hospital direct costs (blood, imaging, implant, laboratory, pharmacy, physical therapy/occupational therapy/speech, room and board) in the MIS versus the open group ($19,512 vs. $23,550, p<.001). Implant costs were similar (p=.686) in both groups, although these accounted for about two-thirds of the hospital direct costs in the MIS cohort ($13,764) and half of these costs ($13,778) in the open group. Hospital payments were $6,248 higher for open TLIF patients compared with the MIS group (p=.267). CONCLUSIONS: MIS TLIF technique demonstrated significant reductions of operative time, LOS, anesthesia time, VAS scores, and EBL compared with the open technique. This reduction in perioperative parameters translated into lower total hospital costs over a 60-day perioperative period. Although hospital reimbursements appear higher in the open group over the MIS group, shorter surgical times and LOS days in the MIS technique provide opportunities for hospitals to reduce utilization of resources and to increase surgical case volume.

Clinical sequelae after rhBMP-2 use in a minimally invasive transforaminal lumbar interbody fusion.

BACKGROUND CONTEXT: Recent reports of postoperative radiculitis, bone osteolysis, and symptomatic ectopic bone formation after recombinant human bone morphogenetic protein-2 (rhBMP-2) use in transforaminal lumbar interbody fusions (TLIFs) are a cause for concern. PURPOSE: To determine the clinical and radiographic complications associated with BMP utilization in a minimally invasive transforaminal lumbar interbody fusion (MIS-TLIF) environment. STUDY DESIGN/SETTING: Retrospective clinical case series at a single institution. PATIENT SAMPLE: Five hundred seventy-three consecutive patients undergoing an MIS-TLIF. OUTCOME MEASURES: Reoperation rates and total costs associated with complications of rhBMP-2 use and pseudarthrosis. METHODS: A retrospective review of 610 consecutive patients undergoing an MIS-TLIF (2007-2010) by a single surgeon at our institution was performed (mean age 48.7 years, range 26-82 years). All patients underwent an MIS laminectomy with bilateral facetectomy, single TLIF cage, unilateral pedicle screw fixation, and 12 mg (large kit) or 4.2 mg (small kit) of rhBMP-2. The BMP-2 collagen-soaked sponge was placed anteriorly in the disc space, followed by local bone graft, and then the cage was filled only with local bone and no BMP-2. Patients were evaluated at 6 months and 1 year with computed tomography (CT) scan. Those demonstrating neuroforaminal bone growth, osteolysis/cage migration, or pseudarthrosis were reviewed, and cost data including direct cost/procedure for both index and revision surgeries were collected. RESULTS: Of the 573 patients, 10 (1.7%) underwent 15 additional procedures based on recalcitrant radiculopathy and CT evidence of neuroforaminal bone growth, vertebral body osteolysis, and/or cage migration. Thirty-nine patients (6.8%) underwent reoperation for clinically symptomatic pseudarthrosis. Bone overgrowth was associated with nerve impingement and radiculopathy in all 10 patients (small kit, n=9; large kit, n=1). Osteolysis and cage migration occurred in 2 (20%) of these same 10 patients. Average total costs were calculated per procedure ($19,224), and the costs for reoperation equaled $14,785 per encounter for neuroforaminal bone growth and $20,267 for pseudarthrosis. CONCLUSIONS: Symptomatic ectopic bone formation, vertebral osteolysis, and pseudarthrosis are recognized complications with the use of rhBMP-2 in MIS-TLIFs. Potential causes include improper dosage and a closed space that prevents the egress of the postoperative BMP-2 fluid collection. Management of these complications has a substantial cost for the patient and the surgeon and needs to be considered with the off-label use of rhBMP-2.

Outcomes of cervical spine surgery in teaching and non-teaching hospitals.

STUDY DESIGN: Retrospective national database analysis. OBJECTIVE: A national population-based database was analyzed to characterize cervical spine procedures performed at teaching and nonteaching hospitals with regards to patient demographics, clinical outcomes/complications, resource use, and costs. SUMMARY OF BACKGROUND DATA: There are mixed reports in the literature regarding the quality and costs of health care provided by teaching hospitals in the United States. However, outcomes of cervical spine surgery based upon teaching status remains largely unknown. METHODS.: Data from the Nationwide Inpatient Sample were obtained from 2002-2009. Patients undergoing elective anterior or posterior cervical fusion, or posterior cervical decompression (i.e., laminoforaminotomy, laminectomy, laminoplasty) for a diagnosis of cervical myelopathy and/or radiculopathy were identified and separated into 2 cohorts (teaching and nonteaching hospitals). Patient demographics, comorbidities, complications, length of hospitalization, costs, and mortality were compared for both groups. Regression analysis was performed to assess independent predictors of mortality. RESULTS: A total of 212,385 cervical procedures were identified from 2002-2009 in the United States, with 54.6% performed at teaching hospitals. More multilevel fusions and posterior approaches were performed in teaching hospitals (P < 0.0005). Patients treated in teaching hospitals trended toward male sex, increased costs, and hospitalizations. Overall, procedure-related complications and inhospital mortality were increased in teaching hospitals. Regression analysis revealed that significant predictors of mortality were age 65 years or more (odds ratio = 3.0) and multiple comorbidities. Teaching status was not a significant predictor of mortality (P = 0.07). CONCLUSION: Patients treated in teaching hospitals for cervical spine surgery demonstrated longer hospitalizations, increased costs, and mortality compared with patients treated in nonteaching hospitals. Incidences of postoperative complications were identified to be higher in teaching hospitals. Possible explanations for these findings are an increased complexity of procedures performed at teaching hospitals. Older age and presence of comorbidities were more significant predictors of inhospital mortality than teaching status. Future studies should identify long-term complications and costs beyond an inpatient setting to assess if differences extend beyond the perioperative period. LEVEL OF EVIDENCE: 4.

Epidemiological trends in cervical spine surgery for degenerative diseases between 2002 and 2009.

STUDY DESIGN: Retrospective analysis of a population-based database. OBJECTIVE: To investigate national epidemiological trends of cervical spine surgical procedures from 2002-2009. SUMMARY OF BACKGROUND DATA: Anterior cervical fusion (ACF), posterior cervical fusion (PCF), and posterior cervical decompression (PCD) are procedures routinely performed for cervical degenerative pathology. Studies regarding epidemiological trends of these procedures is currently lacking in the literature. METHODS: Data from the Nationwide Inpatient Sample of the Healthcare Cost and Utilization Project was obtained for each year between 2002 and 2009. Patients undergoing ACF, PCF, and PCD for the diagnosis of cervical radiculopathy and myelopathy were identified. Demographics, costs, and mortality were assessed in the surgical subgroups. A P value of 0.001 was used to denote significance. RESULTS.: An estimated 1,323,979 cervical spine surgical procedures were performed between 2002 and 2009. There was a significant upward trend in the mean age of patients undergoing cervical spine surgery during this time period. ACF and PCF cohorts demonstrated statistically significant increases in comorbidities and costs from 2002-2009. The PCF group had the greatest mortality, comorbidities, costs, and longest hospitalizations compared with ACF and PCF cohorts across all time periods. CONCLUSION: Our study demonstrates that cervical spine surgical procedures have increased between 2002 and 2009 (P = 0.001). The primary increase in volume is due to the increasing number of ACFs. Despite older patients with more comorbidities undergoing ACF and PCF procedures, mortality has not changed. However, this patient population trended significant increases in costs during this time period. We hypothesize that these increased costs are due to an increased comorbidity burden in patients undergoing ACF or PCF. Results of this study can be used to set benchmarks for future epidemiological investigations in cervical spine surgery. LEVEL OF EVIDENCE: 4.

The incidence and mortality of thromboembolic events in cervical spine surgery.

STUDY DESIGN: Retrospective database analysis. OBJECTIVE: A nationwide population-based database was analyzed to identify the incidence, risk factors, and mortalities associated with venous thromboembolism (VTE) after cervical spine surgery. SUMMARY OF BACKGROUND DATA: Pulmonary embolism (PE) and deep vein thrombosis (DVT) are potential complications that may occur after orthopedic procedures. Incidences of these complications are not well characterized after cervical spine surgery. METHODS: Data from the Nationwide Inpatient Sample database were obtained from 2002 to 2009. Patients undergoing anterior cervical fusion, posterior cervical fusion, and posterior cervical decompression (i.e., laminoforaminotomy, laminectomy, laminoplasty) for the diagnosis of cervical myelopathy and/or radiculopathy were identified. Incidences of PE and DVT were calculated. Comorbidities were calculated using the modified Charlson Comorbidity Index. Mortality associated with these complications was assessed in the 3 surgical subgroups. Statistical analysis was performed to assess significant differences between groups. Logistic regression was used to identify independent predictors of VTE. A P value of <0.0005 was used to denote significance. RESULTS: There were 273,396 cervical procedures recorded in the Nationwide Inpatient Sample database from 2002 to 2009. Posterior cervical fusion-treated patients had statistically the highest incidences of DVT and PE, whereas the lowest PE and DVT rates were found in anterior cervical fusion-treated patients (P < 0.0005). All patients with thromboembolic events had significantly increased rates of mortality, hospitalization, and costs compared with patients without VTE across all procedural groups. Logistic regression analysis demonstrated statistically significant predictors of VTE to be male sex, pulmonary circulation disorders, fluid/electrolyte disorders, and teaching-hospital status. CONCLUSION: Thromboembolic events are potential complications of cervical spine surgery. The highest rates of VTE were identified in those patients undergoing posterior cervical fusion. Regardless of approach, DVT and PEs resulted in increased mortality rates and hospitalization. We recommend a thorough preoperative assessment to identify patients at risk for VTE and treat accordingly to decrease the incidence of these thromboembolic events.

The incidence and mortality of thromboembolic events in lumbar spine surgery.

STUDY DESIGN: Retrospective database analysis. OBJECTIVE: A population-based database was analyzed to identify the incidence, risk factors, and mortality associated with thromboembolic events after lumbar spine surgery. SUMMARY OF BACKGROUND DATA: Pulmonary embolism (PE) and deep vein thrombosis (DVT) are potential complications that may occur after orthopedic procedures. The incidence of these complications is not well characterized after lumbar spine surgery. METHODS: Data from the Nationwide Inpatient Sample was obtained from 2002-2009. Patients undergoing lumbar decompression (LD), or lumbar fusion (LF) for degenerative conditions were identified. Acute PE and DVT incidences and mortality rates were calculated. Comorbidities were calculated using a modified Charlson Comorbidity Index. Statistical analysis was performed using the Student t test for discrete variables and χ test for categorical data. Logistic regression was used to identify independent predictors of thromboembolic events. A P value of less than or equal to 0.0005 was used to denote statistical significance. RESULTS: A total 578,457 LDs and LFs were identified from 2002-2009. DVT incidences were 2.4 and 4.3 per 1000 cases in the LD and LF groups, respectively. PE incidences were 1.0 and 2.6 per 1000 cases in the LD and LF groups, respectively. Patients who had undergone LF with thromboembolic events were younger, had fewer comorbidities, and incurred greater costs than patients who had undergone LD. Statistically significant predictors of DVT were pulmonary circulation disorders, coagulopathy, fluid/electrolyte disorders, anemia, obesity, teaching hospital status, and larger hospitals. Predictors for the development of PE were pulmonary circulation disorders, fluid/electrolyte disorders, anemia, black ethnicity and teaching hospital status. CONCLUSION: Patients undergoing LD or LF are at inherent risk of thromboembolic events. DVT and PE are more common after LF procedures. Preoperative pulmonary circulation disorders, fluid/electrolyte disorders, deficiency anemia, and teaching hospital status were significant risk factors for developing both DVT and PE. Preventive measures in patients at risk may decrease the incidence of thromboembolic events. LEVEL OF EVIDENCE: 4.

Predictive factors of hospital stay in patients undergoing minimally invasive transforaminal lumbar interbody fusion and instrumentation.

STUDY DESIGN: A single-center retrospective study. OBJECTIVE: To identify predictors of length of stay (LOS) days in patients undergoing 1 level minimally invasive (MIS) transforaminal lumbar interbody fusions (TLIF). SUMMARY OF BACKGROUND DATA: Recent studies suggest intraoperative fluid administration, and colloid and crystalloid administration among other intraoperative variables may prolong LOS days and increase complications. Therefore, an understanding of which preoperative, intraoperative, and immediate postoperative parameters best predict immediate LOS days will help risk stratify patients and guide decision making. METHODS: We retrospectively reviewed 104 patients undergoing a MIS TLIF at 1 institution between 2008 and 2010. Two groups were selected on the basis of the time of discharge. Group 1 consisted of patients discharged within 24 hours after surgery and group 2 consisted of patients discharged more than 24 hours after surgery. Multiple regression analysis was performed to determine which preoperative, intraoperative, and postoperative variables were independent predictors of LOS days. RESULTS: Seventy-eight patients (75%) with a LOS greater than 24 hours had significantly higher estimated blood loss, received more crystalloids, had higher total fluids, longer surgical time, lower end of case temperature, lower hemoglobin during hospitalization, and a lower preoperative narcotic use. Multiple regression analysis showed that significant predictors of increased LOS were postoperative creatinine, visual analogue scale score, intraoperative colloids, fluids input at the end of surgical case, crystalloid to colloid ratio, fluid balance, oxycodone (Oxycontin) use, mean percentage of fraction of inspired oxygen, and preoperative hemoglobin. CONCLUSION: Patients undergoing 1 level MIS TLIF for degenerative conditions can overall expect a short LOS postoperatively. Multiple preoperative, intraoperative, and immediate postoperative factors can prolong the LOS in this group. This information should help the surgical team in optimizing their intraoperative patient management.

A comparison of perioperative costs and outcomes in patients with and without workers' compensation claims treated with minimally invasive or open transforaminal lumbar interbody fusion.

STUDY DESIGN: A nonrandomized, nonblinded prospective review. OBJECTIVE: To analyze intraoperative, immediate postoperative, and financial outcomes in worker's compensation (WC) and non-WC patients undergoing either an open or a minimally invasive surgery (MIS) transforaminal lumbar interbody fusion (TLIF). SUMMARY OF BACKGROUND DATA: Few studies have analyzed outcomes in a WC population of MIS TLIFs. METHODS: A total of 66 consecutive patients undergoing a single-level TLIF (open/MIS) were analyzed (33 open and 33 MIS). Twenty-four total WC patients were identified (11 MIS and 13 open). Patients in either cohort (MIS/open) were matched according to insurance status (WC) and medical comorbidities (Charleston disability index). Every patient in this study had a diagnosis of either degenerative disc disease or spondylolisthesis and stenosis. Operative time (min), length of stay (d), estimated blood loss (mL), anesthesia time (min), visual analogue scale scores, and hospital cost/payment amount were assessed (MIS/open and work-comp versus non-work comp). RESULTS: There were no statistically significant differences between MIS WC and non-WC TLIFs with respect to surgical time, length of stay, estimated blood loss, visual analogue scale scores, and anesthesia time. There were no statistically significant differences between open WC and non-WC TLIF patients in all of the same above-mentioned parameters. There were significant differences between MIS (WC and non-WC) and open (WC and non-WC) TLIFs in clinical outcomes. There were statistically significant differences in total costs amounts between WC MIS TLIF and WC open TLIF ($28,060 vs. $33,862, respectively; P = 0.0311) and non-WC MIS TLIF versus non-WC open TLIF groups ($29,429 vs. $32,998, respectively; P = 0.0001). CONCLUSION: Contrary to popular belief, immediate outcomes and hospitalizations between non-WC and WC populations did not differ regardless of surgical technique (MIS/open). Differences occurred in improved outcomes with an MIS TLIF versus an open TLIF even in a WC environment. MIS TLIF WC and non-WC patient hospital costs were lower than their open TLIF counterparts.

Factors affecting reoperations after anterior cervical discectomy and fusion within and outside of a Federal Drug Administration investigational device exemption cervical disc replacement trial.

BACKGROUND CONTEXT: The excellent clinical results of five US Federal Drug Administration (FDA) trials approved for cervical total disc replacement (TDR) (Prestige [Medtronic Sofamor Danek, Memphis, TN, USA], Bryan [Medtronic Sofamor Danek], ProDisc-C [Synthes, West Chester, PA, USA], Kineflex|C [SpinalMotion, Mountain View, CA, USA], and Mobi-C [LDR Spine, Austin, TX, USA]) have recently been published. In these prospective randomized studies, superiority or equivalency of TDR was claimed, citing an 8.7% (23/265), 9.5% (21/221), 8.5% (9/106), 12.2% (14/115), and 6.2% (5/81) (mean = 9.02%) rate of additional related cervical surgical procedures within 2 years in control anterior cervical discectomy and fusion (ACDF) patients, respectively, compared with 1.8% (5/276), 5.8% (14/242), 1.9% (2/103), 11% (15/136), and 1.2% (2/164) (mean = 4.34%) in patients receiving the cervical TDR. The rate of reoperation within 2 years after ACDF seems unusually high. PURPOSE: To assess the rate of and specific indications for early reoperation after ACDF in a cohort of patients receiving the ACDF as part of their customary care. These results are contrasted with similar patients receiving ACDF as the control arm of five FDA investigational device exemption (IDE) studies. STUDY DESIGN: Multisurgeon retrospective clinical series from a single institution. PATIENT SAMPLE: One hundred seventy-six patients with spondylotic radiculopathy or myelopathy underwent ACDF by three surgeons between 2001 and 2005 as part of their clinical practices. All patients had at least 2 years of follow-up with final follow-up within 6 months of completion of this study. OUTCOME MEASURES: Cervical reoperation rates at 2-year follow-up and at 3.5-year follow-up. METHODS: Review of medical records and telephone conversations were completed to determine the number of patients who had undergone a revision cervical procedure. RESULTS: At final follow-up, complete data were available for 159 ACDF patients. Of the 48 patients who underwent single-level ACDF and met criteria for inclusion in the IDE studies, one patient (2.1%) required additional surgery (adjacent-segment degeneration) within 2 years, the duration of follow-up of the five published IDE studies. Of the 159 patients who received single or multilevel ACDF at a mean follow-up of 3.5 years, 12 patients (7.6%) had undergone revision cervical surgery, with three patients (1.9%) undergoing same-level revisions (posterior fusion) and nine patients (5.7%) undergoing adjacent anterior level fusions. Patients who underwent revision same-level surgery typically had the intervention within the first year (mean, 11 months), whereas those requiring adjacent-level fusions typically had surgery later (mean, 29 months). CONCLUSIONS: The present study identifies a 2.1% rate of repeat surgery within 2 years of a single-level ACDF performed during routine clinical practice, which is lower than that reported in the control arm of the Prestige, ProDisc-C, Bryan, Kineflex|C, and Mobi-C FDA trials (mean=9%). Even with longer follow-up including multilevel cases, our reoperation rate (7.6%) compared favorably with the IDE rates. This discrepancy may reflect different thresholds for reoperation in the control arm of a device IDE study compared with routine clinical practice. Additionally, patients enrolled in the single-level-only IDE trial may have received multilevel procedures outside of the study. This factor could result in a higher rate of subsequent surgeries at adjacent levels not addressed at the index procedure. These data suggest that we need to better understand factors driving treatment and, in particular, decisions to reoperate both in and outside of a device trial.

Subaxial cervical and cervicothoracic fixation techniques--indications, techniques, and outcomes.

The subaxial and cervicothoracic junction is a relatively difficult area for spine surgeons to navigate. Because of different transitional stressors at the junction of the smaller cervical vertebrae and the larger thoracic segments, proximity to neurovascular structures, and complex anatomy, extreme care and precision must be assumed during fixation in these regions. Lateral mass screws, pedicle screws, and translaminar screws are currently the standard of choice in the subaxial cervical and upper thoracic spine. This article addresses the relevant surgical anatomy, pitfalls, and pearls associated with each of these fixation techniques.