Reoperations after primary and revision lumbar discectomy: study of a national-level cohort with eight years follow-up.

BACKGROUND CONTEXT: Published rates for disc reherniation following primary discectomy are around 6%, but the ultimate reoperation outcomes in patients after receiving revision discectomy are not well understood. Additionally, any disparity in the outcomes of subsequent revision discectomy (SRD) versus subsequent lumbar fusion (SLF) following primary/revision discectomy remains poorly studied. PURPOSE: To determine the 8-year SRD/SLF rates and time until SRD/SLF after primary/revision discectomy respectively. STUDY DESIGN: Retrospective cohort study. PATIENT SAMPLE: Patients undergoing primary or revision discectomy, with records in the PearlDiver Patient Records Database from the years 2010 to 2019. OUTCOME MEASURES: Subsequent surgery type and time to subsequent surgery. METHODS: Patients were grouped into primary or revision discectomy cohorts based off of the nature of "index" procedure (primary or revision discectomy) using ICD9/10 and CPT procedure codes from 2010 to 19 insurance data sets in the PearlDiver Patient Records Database. Preoperative demographic data was collected. Outcome measures such as subsequent surgery type (fusion or discectomy) and time to subsequent surgery were collected prospectively in PearlDiver Mariner database. Statistical analysis was performed using BellWeather statistical software. A Kaplan-Meier survival analysis of time to SLF/SRD was performed on each cohort, and log-rank test was used to compare the rates of SLF/SRD between cohorts. RESULTS: A total of 20,147 patients were identified (17,849 primary discectomy, 2,298 revision discectomy). The 8-year rates of SRD (6.1% in revision cohort, 4.8% in primary cohort, p<.01) and SLF (10.4% in revision cohort, 6.2% in primary cohort, p<.01) were higher after revision versus primary discectomy. Time to SLF was shorter after revision versus primary discectomy (709 vs. 886 days, p<.01). After both primary and revision discectomy, the 8-year rate of SLF (10.4% in revision cohort, 6.2% in primary cohort, p<.01) is greater than SRD (6.1% in revision cohort, 4.8% in primary cohort, p<.01). CONCLUSIONS: Compared to primary discectomy, revision discectomy has higher rates of SLF (10.4% vs. 6.2%), and faster time to SLF (2.4 vs. 1.9 years) at 8-year follow up.

Changes in kinematics, kinetics, and muscle activity in patients with lumbar spinal stenosis during gait: systematic review.

BACKGROUND CONTEXT: Lumbar spinal stenosis (LSS) is one of the most common orthopaedic conditions and affects more than half a million people over the age of 65 in the US. Patients with LSS have gait dysfunction and movement deficits due to pain and symptoms caused by compression of the nerve roots within a narrowed spinal canal. PURPOSE: The purpose of the current systematic review was to summarize existing literature reporting biomechanical changes in gait function that occur with LSS, and identify knowledge gaps that merit future investigation in this important patient population. STUDY DESIGN/SETTING: This study is a systematic literature review. OUTCOME MEASURES: The current study included biomechanical variables (e.g., kinematic, kinetic, and muscle activity parameters). METHODS: Relevant articles were selected through MEDLINE, Scopus, Embase, and Web of Science. Articles were included if they: 1) included participants with LSS or LSS surgery, 2) utilized kinematic, kinetic, or muscle activity variables as the primary outcome measure, 3) evaluated walking or gait tasks, and 4) were written in English. RESULTS: A total of 11 articles were included in the current systematic review. The patients with LSS exhibited altered gait function as compared to healthy controls. Improvements in some biomechanical variables were found up to one year after surgery, but most gait changes were found within one month after surgery. CONCLUSIONS: Although numerous studies have investigated gait function in patients with LSS, gait alterations in joint kinetics and muscle activity over time remain largely unknown. In addition, there are limited findings of spinal kinematics in patients with LSS during gait. Thus, future investigations are needed to investigate longer-term gait changes with regard to spinal kinematics, joint kinetics, and muscle activity beyond one month after LSS surgery.

The Rate of Heterotopic Ossification Following Cervical Disc Arthroplasty: A Systematic Review and Comparison of Data.

STUDY DESIGN: Systematic review. OBJECTIVES: The purpose of the current study is to determine the overall incidence of Heterotopic Ossification (HO) following cervical disc arthroplasty (CDA) as well as per annum rates. SUMMARY OF BACKGROUND DATA: CDA is a well-established surgical modality for treatment of one- and two-level degenerative disc disease that has failed conservative treatment. Despite its proven mid-term clinical success, the potential for accelerated HO following CDA remains an area of clinical concern. METHODS: A MEDLINE literature search was performed using PubMed, the Cochrane Database of Systematic Reviews, and Embase from January 1980 to February 2018. We included studies involving adult patients, who underwent CDA, documentation of HO, with >12 month follow-up. The pooled results were obtained by calculating the effect size based on the logit event rate. Per annum rates were determined based on weighted averages according to average follow-up period. RESULTS: The initial database review resulted in 230 articles, with 19 articles that met inclusion and exclusion criteria. These pooled results included 2151-disc levels and 1732 patients (50% men and 50% women) who underwent CDA and were evaluated for postoperative HO. The mean age was 45 years with a mean follow-up of 60 months. Sixteen studies reported the occurrence of severe HO resulting in 22.8% of disc levels developing severe HO. When stratifying these studies based on funding type, severe HO was reported at a rate of 21.6% by IDE studies and 27.9% by independent studies. CONCLUSION: The findings of the pooled data show the incidence of severe HO following CDA to be 22.8%. However, there is a significant difference in reported rates of mild and severe HO between IDE and independent data. This alludes to possible underreporting of HO and severity of HO in the industry sponsored IDE studies when compared with independent studies. LEVEL OF EVIDENCE: 2.

Development and validation of risk-adjustment models for elective, single-level posterior lumbar spinal fusions.

BACKGROUND: There is a paucity of literature examining the development and subsequent validation of risk-adjustment models that inform the trade-off between adequate risk-adjustment and data collection burden. We aimed to evaluate patient risk stratification by surgeons with the development and validation of risk-adjustment models for elective, single-level, posterior lumbar spinal fusions (PLSFs). METHODS: Patients undergoing PLSF from 2011-2014 were identified in the American College of Surgeons National Surgical Quality Improvement Program (ACS NSQIP). The derivation cohort included patients from 2011-2013, while the validation cohort included patients from 2014. Outcomes of interest were severe adverse events (SAEs) and unplanned readmission. Bivariate analysis of risk factors followed by a stepwise logistic regression model was used. Limited risk-adjustment models were created and analyzed by sequentially adding variables until the full model was reached. RESULTS: A total of 7,192 and 4,182 patients were included in our derivation and validation cohorts, respectively. Full model performance was similar for the derivation and validation cohorts in both 30-day SAEs (C-statistic =0.66 vs. 0.69) and 30-day unplanned readmission (C-statistic =0.62 vs. 0.65). All models demonstrated good calibration and fit (P≥0.58). Intraoperative variables, laboratory values, and comorbid conditions explained >75% of the variation in 30-day SAEs; ASA class, laboratory values, and comorbid conditions accounted for >80% of model risk prediction for 30-day unplanned readmission. Four variables for the 30-day SAE models (age, gender, ASA ≥3, operative time) and 3 variables for the 30-day unplanned readmission models (age, ASA ≥3, operative time) were sufficient to achieve a C-statistic within four percentage points of the full model. CONCLUSIONS: Risk-adjustment models for PLSF demonstrated acceptable calibration and discrimination using variables commonly found in health records and demonstrated only a limited set of variables were required to achieve an appropriate level of risk prediction.

Radiation Exposure in Minimally Invasive Transforaminal Lumbar Interbody Fusion: The Effect of the Learning Curve.

BACKGROUND: Minimally invasive transforaminal lumbar interbody fusion (MI-TLIF) has comparable fusion rates and outcomes to the open approach, though many surgeons avoid the technique due to an initial learning curve. No current studies have examined the learning curve of MI-TLIF with respect to fluoroscopy time and exposure. Our objective with this retrospective review was to therefore use a repeatable mathematical model to evaluate the learning curve of MI-TLIF with a focus on fluoroscopy time and exposure. METHODS: We conducted a retrospective review of single level, primary fusions performed by a single surgeon during his initial experience with minimally invasive spine surgery. Chronologic case number was plotted against variables of interest, and learning was identified as the point at which the instantaneous rate of change of a curve fit to the data set equaled the average rate of change of the data set. RESULTS: One hundred nine cases were reviewed. Proficiency in operative time was achieved at 38 cases with the first 38 requiring a median of 137 minutes compared to 104 minutes for the latter 71 cases (P < .0001). Mastery of fluoroscopy use occurred at case 51. The median fluoroscopy time for the first 51 cases was 2.8 minutes, which dropped to 2.1 minutes for cases 52 to 109 (P < .0001). The complication rate plateaued after 43 cases, with 3 of 11 total complications occurring in the latter 76 cases. CONCLUSIONS: Our results demonstrate the most gradual learning occurred with respect to fluoroscopy time and exposure, and operative time improved the quickest. LEVEL OF EVIDENCE: IV. CLINICAL RELEVANCE: These findings may guide spine surgeon education and training in minimally invasive techniques, and help determine safe case loads for radiation exposure during the initial learning phase of the technique. The model used to identify the learning curve can also be applied to several fields and surgical techniques.

Predictive Factors and Rates of Fusion in Minimally Invasive Transforaminal Lumbar Interbody Fusion Utilizing rhBMP-2 or Mesenchymal Stem Cells.

BACKGROUND: Several fusion adjuncts exist to enhance fusion rates during minimally invasive transforaminal lumbar interbody fusion (MI-TLIF). The objective of this study was to compare fusion rates in patients undergoing MI-TLIF with either rhBMP-2 or cellularized bone matrix (CBM). METHODS: We conducted a single surgeon retrospective cohort study of patients who underwent MI-TLIF with either rhBMP-2 or CBM placed in an interbody cage. Single and multilevel procedures were included. Fusion was assessed on computed tomography scans at 12-month follow-up by an independent, blinded, board-certified neuroradiologist. Fusion rates and rate of revision surgery were compared with a Fisher exact test between the 2 groups. A multivariate regression analysis was performed to identify patient factors that were predictive of radiographic nonunion after MI-TLIF. RESULTS: A total of 93 fusion levels in 78 patients were reviewed. Thirty-nine patients received CBM, and 39 patients received rhBMP-2. The patients receiving rhBMP-2 were older on average (61.4 vs 55.6, P = .03). The overall fusion rate was 68% in the CBM group (32/47 levels) and 78% in the rhBMP-2 group (36/46) (P = .35). Only preoperative hypertension was predictive of radiographic nonunion (odds ratio = 3.5, P = .05). There were 3 smokers in the CBM group and 4 smokers in the BMP group, and 1 in each group experienced radiographic pseudarthrosis. A total of 4 patients, 3 in the CBM group and 1 in the BMP group (P = .61), required revision for symptomatic pseudarthrosis. All of these patients had a single-level index procedure. CONCLUSIONS: There were no differences in radiographic fusion and rate of revision surgery in patients who underwent MI-TLIF with either rhBMP-2 or CBM as fusion adjuncts. LEVEL OF EVIDENCE: 3. CLINICAL RELEVANCE: Both rhBMP-2 and CBMs can be used as effective fusion adjuncts without any clear advantage of one over the other.

Negative Sagittal Balance Following Adult Spinal Deformity Surgery.

STUDY DESIGN: Retrospective cohort study. OBJECTIVE: Elucidate negative sagittal balance following adult spinal deformity surgery. METHODS: We conducted a retrospective review of adult spinal deformity patients who underwent long fusion (>5 levels) to the sacrum by a single surgeon at a single institution between 2011 and 2015. Patients were divided into cohorts of postoperative sagittal vertical axis (SVA) <-10 mm, between -10 and +10 mm, or >+10 mm, denoted as groups 1, 2, and 3, respectively. Univariate analysis compared preoperative factors between the groups, and a multivariable logistic regression model was used to determine independent risk factors for developing a negative sagittal balance (SVA<-10 mm) following adult spinal deformity correction. RESULTS: We reviewed 8 patients in group 1, 9 patients in group 2, and 25 patients in group 3. The average postoperative SVA for group 1, group 2, and group 3 were -30.99, +3.67, and +55.56 mm, respectively. There was a trend toward higher upper-instrumented vertebra (UIV) in group 1 (T2) compared with group 2 (T10) and group 3 (T9) (P = .05). A trend toward lower preoperative SVA in groups 1 and 2 compared with group 3 was also seen (+53.36 vs +71.73 vs +122.80 mm) (P = .06). Finally, we found a trend toward lower body mass index in group 1 compared with groups 2 and 3 (24.71 vs 25.92 vs 29.33 kg/m2) (P = .07). Based on multivariable regression, higher UIV was found to be a statistically significant independent predictor for developing a postoperative negative sagittal balance of <-10 mm (P = .02, odds ratio = 0.67). CONCLUSIONS: Our results demonstrate that a higher UIV may predispose patients undergoing adult spinal deformity correction to have a postoperative negative sagittal balance.

Return to Play in Adolescent Athletes With Symptomatic Spondylolysis Without Listhesis: A Meta-Analysis.

STUDY DESIGN: Meta-analysis. OBJECTIVES: To assess return to play (RTP) rates in adolescent athletes with lumbar spondylolysis without spondylolisthesis treated conservatively or operatively. METHODS: A review of Medline, EMBASE, and Cochrane Reviews was performed. The pooled results were performed by calculating the effect size based on the logit event rate. Studies were weighted by the inverse of the variance. Confidence intervals were reported at 95%. Heterogeneity was assessed using the Q statistic and I2 value. RESULTS: The initial literature search resulted in 724 articles, of which 29 were deemed relevant on abstract review. Overall, 11 studies provided data for 376 patients with a pars interarticularis defect. Return to athletic competition, based on logit event rate, was found to be statistically favored after both nonoperative and operative treatment (92.2% vs 90.3%). There was no heterogeneity noted among the studies reporting nonoperative treatment (Q value of 4.99 and I2 value of 0). There was mild heterogeneity within the operative studies (Q value of 3.54 and I2 value of 15.18). CONCLUSIONS: Adolescent athletes RTP 92.2% of the time with nonoperative management, compared with 90.3% when treated operatively, though both treatment groups strongly favor RTP. As this is the first study to pool results of all relevant literature, it provides strong evidence to guide decision making and help manage expectations in this unique patient population.

Cervical Laminoplasty: Indications, Surgical Considerations, and Clinical Outcomes.

Cervical laminoplasty was initially described for the management of cervical myelopathy resulting from multilevel stenosis secondary to ossification of the posterior longitudinal ligament. The general concepts are preservation of the dorsal elements, preservation of segmental motion, and expansion of the spinal canal via laminar manipulation. No clear evidence suggests that laminoplasty is superior to either posterior laminectomy or anterior cervical diskectomy and fusion. However, laminoplasty has its own advantages, indications, and complications. Surgeons have refined the technique to decrease complication rates and improve efficacy. Recent efforts have highlighted less invasive approaches that are muscle sparing and associated with less postoperative morbidity. Although the long-term outcomes suggest that cervical laminoplasty is safe and effective, continued research on the development of novel modifications that decrease common complications, such as C5 nerve palsy, axial neck pain, and loss of lordosis, is required.

Comparing the 5-Year Health State Utility Value of Cervical Disc Replacement and Anterior Cervical Discectomy and Fusion.

STUDY DESIGN: Health utility analysis. OBJECTIVES: To determine the health state utility (HSU) of 1- and 2-level anterior cervical discectomy and fusion (ACDF) and cervical disc replacement (CDR). METHODS: Data from the Medtronic Prestige Cervical Disc investigational device exemption studies was used. Four groups were defined: 1-level ACDF, 1-level CDR, 2-level ACDF, and 2-level CDR. The 36-item Short Form Health Survey (SF-36) was collected at baseline, 12 months, 24 months, 36 months, and 60 months postoperatively and converted into utility scores for each time point. A repeated-measures 1-way analysis of variance (ANOVA) was used to detect differences among groups. Tukey's method for multiple comparisons was used to determine which means within the groups were statistically different (P < .05). RESULTS: We found a statistically significant difference in HSU among groups as determined by repeated-measures 1-way ANOVA (P = .0008). Post hoc analysis indicated that 1-level ACDF had a statistically lower utility score compared with 1- and 2-level CDR (P = .04 and P = .02, respectively). Similarly, 2-level ACDF had lower utility values compared with 2-level CDR (P = .010). One-level ACDF utility values were not different from 2-level ACDF values (P = .55). Similarly, 1-level CDR and 2-level CDR did not have different utility values (P = .67). CONCLUSIONS: Overall, CDR had higher health state utility scores for 1- and 2-level procedures at every time point. This study indicates that CDR results in a higher postoperative health utility state than ACDF, and may therefore be an effective alternative to ACDF for treating degenerative conditions of the cervical spine.

Comparing the Incidence of Index Level Fusion Following Minimally Invasive Versus Open Lumbar Microdiscectomy.

STUDY DESIGN: Retrospective cohort study. OBJECTIVES: To determine the incidence of index level fusion following open or minimally invasive lumbar microdiscectomy. METHODS: We conducted a retrospective review of 174 patients with a symptomatic single-level lumbar herniated nucleus pulposus who underwent microdiscectomy via a mini-open approach (MIS; 39) or through a minimally invasive dilator tube (135). Outcomes of interest included revision microdiscectomy and the ultimate need for index level fusion. Continuous variables were analyzed with independent sample t test, and χ2 analysis was used for categorical data. A multivariate regression analysis was performed to identify predictive factors for patients that required index level fusion after lumbar microdiscectomy. RESULTS: There was no difference in patient demographics in the open and MIS groups aside from length of follow-up (60.4 vs 40.03 months, P < .0001) and body mass index (24.72 vs 27.21, P = .03). The rate of revision microdiscectomy was not statistically significant between open and MIS approaches (10.3% vs 10.4%, P = .90). The rate of patients who ultimately required index level fusion approached significance, but was not statistically different between open and MIS approaches (10.3% vs 4.4%, P = .17). Multivariate regression analysis indicated that the need for eventual index level fusion after lumbar microdiscectomy was statistically predicted in smokers and those patients who underwent revision microdiscectomy (P < .05) in both open and MIS groups. CONCLUSIONS: Our results suggest a low likelihood of patients ultimately requiring fusion following microdiscectomy with predictors including smoking status and a history of revision microdiscectomy.

Investigating the 7-Year Cost-Effectiveness of Single-Level Cervical Disc Replacement Compared to Anterior Cervical Discectomy and Fusion.

STUDY DESIGN: Cost-effectiveness analysis. OBJECTIVES: To determine the 7-year cost-effectiveness of cervical disc replacement (CDR) and anterior cervical discectomy and fusion (ACDF). METHODS: We analyzed 7-year Short Form-36 Health Survey data collected from the Prestige Cervical Disc investigational device exemption study (IDE). The SF-6D algorithm was used to convert this data into health state utilities. Costs were calculated from the payer perspective, and quality adjusted life years (QALYs) were used to represent effectiveness. A Markov transition-state model was used to evaluate the cost-effectiveness of single-level CDR versus ACDF, and a Monte Carlo simulation was performed to assess the probabilistic sensitivity of the model. RESULTS: CDR generated a 7-year cost of $172 989 compared to a 7-year cost of $143 714 for ACDF. CDR generated 4.53 QALYs compared to 3.85 QALYs generated by ACDF. The cost-effectiveness ratio of CDR was $38 247/QALY, while the cost-effectiveness ratio of ACDF was $37 325/QALY. The incremental cost-effectiveness ratio of CDR was $43 522/QALY, under the willingness to pay threshold of $50 000/QALY. Our probabilistic sensitivity analysis demonstrated CDR would be chosen 56% of the time based on 10 000 simulations. CONCLUSIONS: Single-level CDR and ACDF were both cost-effective strategies at 7 years for treating degenerative conditions of the cervical spine. Both the Markov simulation and the Monte Carlo simulation demonstrate CDR to be the more cost-effective strategy at 7 years. Continued analysis of IDE data should be performed to validate long-term cost-effectiveness of these treatment strategies.

Is Cervical Bracing Necessary After One- and Two-Level Instrumented Anterior Cervical Discectomy and Fusion? A Prospective Randomized Study.

STUDY DESIGN: Prospective randomized control trial. OBJECTIVE: To investigate the role of cervical collars in postoperative care following 1- and 2-level instrumented anterior cervical discectomy and fusion (ACDF). METHODS: The Cervical Spine Research Society Resident Fellow Grant funded this project. Fifty consecutive patients undergoing 1- or 2-level ACDF surgery were randomized into groups receiving either no brace or a cervical brace for 6 weeks postoperatively. Neck Disability Index scores were recorded preoperatively and at regular follow-up visits up to 1 year. Computed tomography scans were read 1 year postoperatively to determine fusion rates, and subsidence was measured as change in middle vertebral distance between initial postoperative and 6-month follow-up lateral cervical radiographs. RESULTS: Twenty-two patients were in the no-brace group, and 22 patients were in the brace group at final follow-up, with an average age of 50 and 55 years, respectively. The no-brace group had a total of 32 operative levels, whereas the brace group had 38 operative levels. There was no statistically significant difference in 1-year postoperative Neck Disability Index scores between the brace (9.30) and no-brace (6.95) groups (P = .28), in 6-month subsidence of all operative levels between the brace (0.85 mm) and no-brace (0.79 mm) groups (P = .72), or in the proportion of fused levels between the brace (89%) and no-brace (97%) groups (P = .37). CONCLUSIONS: Our results suggest no advantage in wearing a cervical brace following 1- or 2-level ACDF surgery with respect to 1-year outcome scores, 1-year fusion rates, and 6-month subsidence.

Posterolateral fusion (PLF) versus transforaminal lumbar interbody fusion (TLIF) for spondylolisthesis: a systematic review and meta-analysis.

BACKGROUND CONTEXT: Lumbar fusion is an effective and durable treatment for symptomatic lumbar spondylolisthesis; however, the current literature provides insufficient evidence to recommend an optimal surgical fusion strategy. PURPOSE: The present study aims to compare the clinical outcomes, fusion rates, blood loss, and operative times between open posterolateral lumbar fusion (PLF) alone and open transforaminal lumbar interbody fusion (TLIF) + posterolateral fusion for spondylolisthesis. STUDY DESIGN: This is a systematic literature review and meta-analysis of English language studies for the treatment of spondylolisthesis with PLF versus PLF + TLIF. PATIENT SAMPLE: Data were obtained from published randomized controlled trials (RCTs) and retrospective cohort studies. OUTCOME MEASURES: Clinical outcomes included Oswestry Disability Index (ODI), back pain, leg pain, and health-related quality of life (HRQOL) scores. Fusion rate, operative time, blood loss, and infection rate were also assessed. METHODS: A literature search of three electronic databases was performed to identify investigations performed comparing PLF alone with PLF + TLIF for treatment of low-grade lumbar spondylolisthesis. The summary effect size was assessed from pooling observational studies for each of the outcome variables, with odds ratios (ORs) used for fusion and infection rate, mean difference used for improvement in ODI and leg pain as well as operative time and blood loss, and standardized mean difference used for improvement in back pain and HRQOL outcomes. Studies were weighed based on the inverse of the variance and heterogeneity. Heterogeneity was assessed using the I2-an estimate of the error caused by between-study variation. Effect sizes from the meta-analysis were then compared with data from the RCTs to assess congruence in outcomes. RESULTS: The initial literature search yielded 282 unique, English language studies. Seven were determined to meet our inclusion criteria and were included in our qualitative analysis. Five observational studies were included in our quantitative meta-analysis. The pooled fusion success rates were 84.7% (100/118) in the PLF group and 94.3% (116/123) in the TLIF group. Compared with TLIF patients, PLF patients had significantly lower odds of achieving solid arthrodesis (OR 0.33, 95% confidence interval [CI] 0.13-0.82, p=.02; I2=0%). With regard to improvement in back pain, the point estimate for the effect size was -0.27 (95% CI -0.43 to -0.10, p=.002; I2=0%), in favor of the TLIF group. For ODI, the pooled estimate for the effect size was -3.73 (95% CI -7.09 to -0.38, p=.03; I2=35%), significantly in favor of the TLIF group. Operative times were significantly shorter in the PLF group, with a summary effect size of -25.55 (95% CI -43.64 to -7.45, p<.01; I2=54%). No significant difference was observed in leg pain, HRQOL improvement, blood loss, or infection rate. Our meta-analysis results were consistent with RCTs, in favor of TLIF for achieving radiographic fusion and greater improvement in ODI and back pain. CONCLUSIONS: Our results demonstrate that for patients undergoing fusion for spondylolisthesis, TLIF is superior to PLF with regard to achieving radiographic fusion. However, current data only provide weak support, if any, favoring TLIF over PLF for clinical improvement in disability and back pain.

The 5-year cost-effectiveness of two-level anterior cervical discectomy and fusion or cervical disc replacement: a Markov analysis.

BACKGROUND CONTEXT: Anterior cervical discectomy and fusion (ACDF) and cervical disc replacement (CDR) are both acceptable surgical options for the treatment of cervical myelopathy and radiculopathy. To date, there are limited economic analyses assessing the relative cost-effectiveness of two-level ACDF versus CDR. PURPOSE: The purpose of this study was to determine the 5-year cost-effectiveness of two-level ACDF versus CDR. STUDY DESIGN: The study design is a secondary analysis of prospectively collected data. PATIENT SAMPLE: Patients in the Prestige cervical disc investigational device exemption (IDE) study who underwent either a two-level CDR or a two-level ACDF were included in the study. OUTCOME MEASURES: The outcome measures were cost and quality-adjusted life years (QALYs). MATERIALS AND METHODS: A Markov state-transition model was used to evaluate data from the two-level Prestige cervical disc IDE study. Data from the 36-item Short Form Health Survey were converted into utilities using the short form (SF)-6D algorithm. Costs were calculated from the payer perspective. QALYs were used to represent effectiveness. A probabilistic sensitivity analysis (PSA) was performed using a Monte Carlo simulation. RESULTS: The base-case analysis, assuming a 40-year-old person who failed appropriate conservative care, generated a 5-year cost of $130,417 for CDR and $116,717 for ACDF. Cervical disc replacement and ACDF generated 3.45 and 3.23 QALYs, respectively. The incremental cost-effectiveness ratio (ICER) was calculated to be $62,337/QALY for CDR. The Monte Carlo simulation validated the base-case scenario. Cervical disc replacement had an average cost of $130,445 (confidence interval [CI]: $108,395-$152,761) with an average effectiveness of 3.46 (CI: 3.05-3.83). Anterior cervical discectomy and fusion had an average cost of $116,595 (CI: $95,439-$137,937) and an average effectiveness of 3.23 (CI: 2.84-3.59). The ICER was calculated at $62,133/QALY with respect to CDR. Using a $100,000/QALY willingness to pay (WTP), CDR is the more cost-effective strategy and would be selected 61.5% of the time by the simulation. CONCLUSIONS: Two-level CDR and ACDF are both cost-effective strategies at 5 years. Neither strategy was found to be more cost-effective with an ICER greater than the $50,000/QALY WTP threshold. The assumptions used in the analysis were strongly validated with the results of the PSA.

Impact of Operation Time on 30-Day Complications After Adult Spinal Deformity Surgery.

STUDY DESIGN: Retrospective analysis of prospectively collected data. OBJECTIVE: There is a paucity of data on the effect of operative duration on postoperative complications during adult spinal deformity surgery (ASDS). The study attempts to explore and quantify the association between increased operation times and postoperative complications. METHODS: A retrospective cohort analysis was performed on the American College of Surgeons National Surgical Quality Improvement Program (ACS-NSQIP) database from 2010 to 2014. Patients (≥18 years of age) from the NSQIP database undergoing ASDS were separated into cohorts based on quartiles of operation duration. Chi-square and multivariate logistic regression models were used to identify risk factors. RESULTS: A total of 5338 patients met the inclusion criteria and were divided per quartiles based on operative duration in minutes (154, 235, 346, and 1156 minutes). Multivariate logistic regressions revealed that in comparison to the lowest quartile of operative duration, the highest quartile group was associated significantly with length of stay ≥5 days (odds ratio [OR] = 5.85), any complication (OR = 9.88), wound complication (OR = 5.95), pulmonary complication (OR = 2.85, P = .001), venous thromboembolism (OR = 12.37), intra-/postoperative transfusion (OR = 12.77), sepsis (OR = 5.27), reoperations (OR = 1.48), and unplanned readmissions (OR = 1.29). The odds ratio was higher when comparing a higher quartile group with the reference group across all associations. P < .001 unless otherwise noted. CONCLUSION: ASDS operation time is associated with multiple postoperative complications, including, but not limited to, wound and pulmonary complications, venous thromboembolism, postoperative transfusion, length of stay ≥5 days, sepsis, reoperation, and unplanned readmission.

Tandem Spinal Stenosis: A Systematic Review.

BACKGROUND: Tandem spinal stenosis refers to spinal canal diameter narrowing in at least 2 distinct regions of the spine, most commonly the lumbar and cervical regions. This entity can be an asymptomatic radiographic finding, or it can present with severe myelopathy and lower-extremity symptoms. Tandem spinal stenosis may impact surgeon decision-making when planning either cervical or lumbar spine surgery, and there is currently no consensus in the literature regarding the treatment algorithm for operative intervention. METHODS: A MEDLINE literature search was performed using PubMed, the Cochrane Database of Systematic Reviews, and Embase from January 1980 to February 2015 using Medical Subject Heading queries for the terms "tandem spinal stenosis," "cervical stenosis AND lumbar stenosis," and "concomitant spinal stenosis." We included studies involving adult patients, tandem spinal stenosis of the cervical and lumbar regions, and a minimum of 5 patients. Articles that did not discuss spinal disorders or only explored disorders at a single spinal region were excluded. RESULTS: The initial database review resulted in 234 articles. After abstracts were reviewed, only 17 articles that met inclusion criteria were identified: 2 cadaveric studies, 5 clinical studies of patients with radiographic tandem spinal stenosis, and 10 clinical studies of patients with symptomatic tandem spinal stenosis. CONCLUSIONS: Tandem spinal stenosis is a common condition present in up to 60% of patients with spinal stenosis. This disorder, however, is often overlooked, which can lead to serious complications. Identification of tandem spinal stenosis is paramount as a first step in management and, although there is still no preferred intervention, both staged and simultaneous procedures have been shown to be effective. Surgeons may utilize a single, staged, or combined approach to decompression, always addressing cervical myelopathy as a priority.

A Matched Cohort Analysis Comparing Stand-Alone Cages and Anterior Cervical Plates Used for Anterior Cervical Discectomy and Fusion.

STUDY DESIGN: Retrospective cohort study. OBJECTIVE: To compare perioperative characteristics of stand-alone cages and anterior cervical plates used for anterior cervical discectomy and fusion (ACDF). METHODS: We reviewed 40 adult patients who received a stand-alone cage for elective ACDF and matched them with 40 patients who received an anterior cervical plate. We statistically compared operative time, length of stay, proportion of ambulatory cases, overall complications necessitating a trip to the ED, readmission, or reoperation related to index procedure. RESULTS: There were 21 women and 19 men in the plate cohort with average ages of 53 years ± 12 and 20 women and 20 men in the stand-alone group with an average age of 52 years ± 11. With no statistical difference in total number, the plate group experienced 4 short-term (within 90 days of discharge) complications, including 3 patients who visited the emergency department for dysphagia and 1 who visited the emergency department for severe back pain, while the stand-alone group experienced 0 complications. There was no significant difference in operative time between the stand-alone group (75.35 min) and the plate group (81.35 min; P = .37). There was a significant difference between the proportion of ambulatory cases in the stand-alone group (25) and the plate group (6; P < .0001). CONCLUSION: Our results demonstrate that stand-alone cages have fewer complications compared to anterior plating, with a lower trend of incidence of postoperative dysphagia. Stand-alone cages may offer the advantage of sending patients home ambulatory after ACDF surgery.

Bone morphogenetic protein use in spine surgery in the United States: how have we responded to the warnings?

BACKGROUND CONTEXT: Recombinant human bone morphogenetic protein-2 (rhBMP-2) has been widely adopted as a fusion adjunct in spine surgery since its approval in 2002. A number of concerns regarding adverse effects and potentially devastating complications of rhBMP-2 use led to a Food and Drug Administration (FDA) advisory issued in 2008 cautioning its use, and a separate warning about its potential complications was published by The Spine Journal in 2011. PURPOSE: To compare trends of rhBMP-2 use in spine surgery after the FDA advisory in 2008 and The Spine Journal warning in 2011. STUDY DESIGN: Retrospective cross-sectional study using a national database. PATIENT SAMPLE: All patients from 2002 to 2013 who underwent spinal fusion surgery at an institution participating in the Nationwide Inpatient Sample (NIS). OUTCOME MEASURES: Proportion of spinal fusion surgeries using rhBMP-2. METHODS: We queried the NIS from 2002 to 2013 and used International Classification of Diseases, Ninth Revision, Clinical Modification (ICD-9-CM) procedure codes to identify spinal fusion procedures and those that used rhBMP-2. Procedures were subdivided into primary and revision fusions, and by region of the spine. Cervical and lumbosacral fusions were further stratified into anterior and posterior approaches. The percentage of cases using BMP was plotted across time. A linear regression was fit to the data from quarter 3 of 2008 (FDA advisory) through quarter 1 of 2011, and a separate regression was fit to the data from quarter 2 of 2011 (The Spine Journal warning) onward. The slopes of these regression lines were statistically compared to determine differences in trends. No funding was received to conduct this study, and no authors had any relevant conflicts of interest. RESULTS: A total of 4,167,079 patients in the NIS underwent spinal fusion between 2002 and 2013. We found a greater decrease in rhBMP-2 use after The Spine Journal warning compared with the FDA advisory for all fusion procedures (p=.006), primary fusions (p=.006), and revision fusions (p=.004). Lumbosacral procedures also experienced a larger decline in rhBMP-2 use after The Spine Journal article as compared with the FDA warning (p=.0008). This pattern was observed for both anterior and posterior lumbosacral fusions (p≤.0001 for both). Anterior cervical fusion was the only procedure that demonstrated a decline in rhBMP-2 use after the FDA advisory that was statistically greater than after The Spine Journal article (p=.02). CONCLUSIONS: Warnings sanctioned through the spine literature may have a greater influence on practice of the spine surgery community as compared with advisories issued by the FDA.Comprehensive guidelines regarding safe and effective use of rhBMP-2 must be established.

Navigation and Robotics in Spinal Surgery: Where Are We Now?

Spine surgery has experienced much technological innovation over the past several decades. The field has seen advancements in operative techniques, implants and biologics, and equipment such as computer-assisted navigation and surgical robotics. With the arrival of real-time image guidance and navigation capabilities along with the computing ability to process and reconstruct these data into an interactive three-dimensional spinal "map", so too have the applications of surgical robotic technology. While spinal robotics and navigation represent promising potential for improving modern spinal surgery, it remains paramount to demonstrate its superiority as compared to traditional techniques prior to assimilation of its use amongst surgeons.The applications for intraoperative navigation and image-guided robotics have expanded to surgical resection of spinal column and intradural tumors, revision procedures on arthrodesed spines, and deformity cases with distorted anatomy. Additionally, these platforms may mitigate much of the harmful radiation exposure in minimally invasive surgery to which the patient, surgeon, and ancillary operating room staff are subjected.Spine surgery relies upon meticulous fine motor skills to manipulate neural elements and a steady hand while doing so, often exploiting small working corridors utilizing exposures that minimize collateral damage. Additionally, the procedures may be long and arduous, predisposing the surgeon to both mental and physical fatigue. In light of these characteristics, spine surgery may actually be an ideal candidate for the integration of navigation and robotic-assisted procedures.With this paper, we aim to critically evaluate the current literature and explore the options available for intraoperative navigation and robotic-assisted spine surgery.