Long-term outcomes of revision fusion for lumbar pseudarthrosis: clinical article

Temporal Shape Changes of Pedicle Screw-rod Constructs After Lumbar Interbody Fusion

STUDY DESIGN

Retrospective multicenter study.

OBJECTIVE

To examine the shape change of screw-rod constructs over time after short-segment lumbar interbody fusion and to clarify its relationship to clinical characteristics.

SUMMARY OF BACKGROUND DATA

No study has focused on the shape change of screw-rod constructs after short-segment fusion and its clinical implications.

METHODS

One hundred eight patients who had single-level lumbar interbody fusion with pedicle screws and cages were enrolled. Three-dimensional (3D) images of screw-rod constructs were generated from baseline CT on the day after surgery and follow-up CT and were superposed on the right and left side, respectively, using the iterative closest point algorithm. The shape change was quantitatively assessed by computing the median distance between the 3D images, which was defined as the shape change value. Among the 5 time-course categories of follow-up CT (≤1, 2-3, 4-6, 7-12, and ≥13 months), the shape change values were compared. The relationships between the shape change values and clinical characteristics, such as age, CT-derived vertebral bone mineral density, screw and rod materials, and postoperative interbody fusion status, cage subsidence, and screw loosening, were evaluated.

RESULTS

A total of 237 follow-up CTs were included (≤1 [34 scans], 2-3 [33 scans], 4-6 [80 scans], 7-12 [48 scans], and ≥13 months [42 scans]) because many patients underwent multiple follow-up CTs. There were significant differences in shape change values among the time-course categories ( P <0.001 in Kruskal-Wallis test). Most shape changes occurred within 6 months postoperatively, with no significant changes observed at 7 months or more. There were no significant relationships between the shape change values and each clinical characteristic.

CONCLUSIONS

The temporal shape changes of screw-rod constructs following short-segment lumbar interbody fusion progressed up to 6 months after surgery but not significantly thereafter.

The Impact of Unplanned Reoperation Following Adult Spinal Deformity Surgery: A Prospective Longitudinal Cohort Study with 5-Year Follow-up

BACKGROUND

The long-term impact of reoperations following adult spinal deformity (ASD) surgery is still poorly understood. Our aim was to identify the relationship between unplanned reoperation and health-related quality of life (HRQoL) gain at 2 and 5 years of follow-up.

METHODS

We included patients enrolled in a prospective ASD database who underwent surgery ≥5 years prior to the start of the study and who had 2 years of follow-up data. Adverse events (AEs) leading to an unplanned reoperation, the time of reoperation occurrence, invasiveness (blood loss, surgical time, hospital stay), and AE resolution were assessed. HRQoL was measured with use of the Oswestry Disability Index, Scoliosis Research Society-22, and Short Form-36. Linear models controlling for baseline data and index surgery characteristics were utilized to assess the relationships between HRQoL gain at 2 and 5-year follow-up and the number and invasiveness of reoperations. The association between 5-year HRQoL gain and the time of occurrence of the unplanned reoperation and that between 5-year HRQoL gain and AE resolution were also investigated.

RESULTS

Of 361 eligible patients, 316 (87.5%) with 2-year follow-up data met the inclusion criteria and 258 (71.5%) had 5-year follow-up data. At the 2-year follow-up, 96 patients (30.4%) had a total of 165 unplanned reoperations (1.72 per patient). At the 5-year follow-up, 73 patients (28.3%) had a total of 117 unplanned reoperations (1.60 per patient). The most common cause of reoperations was mechanical complications (64.9%), followed by surgical site infections (15.7%). At the 5-year follow-up, the AE that led to reoperation was resolved in 67 patients (91.8%). Reoperation invasiveness was not associated with 5-year HRQoL scores. The number of reoperations was associated with lesser HRQoL gain at 5 years for all HRQoL measures. The mean associated reduction in HRQoL gain per unplanned reoperation was 41% (range, 19% to 66%). Reoperations resulting in no resolution of the AE or resolution with sequelae had a greater impact on 5-year follow-up HRQoL scores than reoperations resulting in resolution of the AE.

CONCLUSIONS

A postoperative, unplanned reoperation following ASD surgery was associated with lesser gain in HRQoL at 5 years of follow-up. The association did not diminish over time and was affected by the number, but not the magnitude, of reoperations. Resolution of the associated AE reduced the impact of the unplanned reoperation.

LEVEL OF EVIDENCE

Prognostic Level II. See Instructions for Authors for a complete description of levels of evidence.

The Influence of Titanium-coated Poryetheretherketone Cages in Fusion Status after Posterior Lumbar Interbody Fusion with Cortical Bone Trajectory Screw Fixation

OBJECTIVE

Posterior lumbar interbody fusion (PLIF) with cortical bone trajectory (CBT) screw fixation (CBT-PLIF) shows potential for reducing adjacent segmental disease. Previously, our investigations revealed a relatively lower fusion rate with the use of carbon fiber-reinforced polyetheretherketone (CP) cages in CBT-PLIF compared with traditional pedicle screw fixation (PS-PLIF) using CP cages. This study aims to evaluate whether the implementation of titanium-coated polyetheretherketone (TP) cages can enhance fusion outcomes in CBT-PLIF.

METHODS

A retrospective analysis was conducted on 68 consecutive patients who underwent CBT-PLIF with TP cages (TP group) and 89 patients who underwent CBT-PLIF with CP cages (CP group). Fusion status was assessed using computed tomography at 1 year postoperatively and dynamic plain radiographs at 2 years postoperatively.

RESULTS

No statistically significant differences in fusion rates were observed at 1 and 2 years postoperatively between the TP group (86.8% and 89.7%, respectively) and the CP group (77.5% and 88.8%, respectively). Notably, the CP group exhibited a significant improvement in fusion rate from 1 to 2 years postoperatively (P = 0.002), while no significant improvement was observed in the TP group.

CONCLUSIONS

Examination of temporal changes in fusion rates reveals that only the TP group achieved a peak fusion rate 1 year postoperatively. This implies that TP cages may enhance the fusion process even after CBT-PLIF. Nevertheless, the definitive efficacy of TP cages for CBT-PLIF remains uncertain in the context of overall fusion rates.

Effect of revision sacroiliac joint fusion on unresolved pain and disability: a retrospective cohort study

PURPOSE

The sacroiliac (SI) joint is recognized as a source of low back pain in 15-30% of patients. Though randomized controlled trials have shown clinical improvement following SI joint fusion in 83.1% of patients, revision rates of 2.9% within 2 years have been reported. There is a paucity of literature reviewing this small yet significant population of patients requiring revision surgery.

METHODS

Following IRB approval, retrospective review of patients, who underwent a revision SI joint fusion from 2009 to 2021 was completed. Patient-reported outcomes were measured before and at each clinic visit after surgery with visual analoge scale (VAS) for back pain and Oswestry Disability Index (ODI). Patient characteristics (chronic opiate use and prior lumbar fusion) and surgical factors (operative approach, type/number of implants and use of bone graft) were recorded. Patient-reported outcomes were evaluated with Paired t and Wilcoxon signed rank tests. Univariate and multivariate logistic regression determined if patients met the minimally clinical important differences (MCID) for VAS-back pain and ODI scores at 1 year.

RESULTS

Fifty-two patients (77% female) with an average age of 49.1 (SD ± 11.1) years met inclusion criteria. Forty-four had single sided revisions and eight bilateral revisions. At 1 year follow-up there was no significant improvement in VAS-Back (p = 0.06) or ODI (p = 0.06). Patients with chronic opioid use were 8.5 times less likely to achieve the MDC for ODI scores (OR 0.118, p = 0.029). There was no difference in outcomes when comparing the different surgical approaches (p = 0.41).

CONCLUSION

Our study demonstrates patients undergoing revision surgery have moderate improvement in low back pain, however, few have complete resolution of their symptoms. Specific patient factors, such as chronic opiate use and female sex may decrease the expected improvement in patient-reported outcomes following surgery. Failure to obtain relief may be due to incorrect indications, lack of biologic fusion and/or presence of co-pathologies. Further clinical examination and consistent long-term follow-up, clarify the role revision surgery plays in long-term patient outcomes.

Adult spinal deformity patients revised for pseudarthrosis have comparable two-year outcomes to those not undergoing any revision surgery

PURPOSE

This study aimed to evaluate whether adult spinal deformity patients undergoing revision for symptomatic pseudarthrosis have comparable two-year outcomes as patients who do not experience pseudarthrosis.

METHODS

Patients whose indexed procedure was revision for pseudarthrosis (pseudo) were compared with patients who underwent a primary procedure and did not have pseudarthrosis by 2Y post-op (non-pseudo). Patients were propensity-matched (PSM) based on baseline (BL) sagittal alignment, specifically C7SVA and CrSVA-Hip. Key outcomes were 2Y PROs (SRS and ODI) and reoperation. All patients had a minimum follow-up period of two years.

RESULTS

A total of 224 patients with min 2-year FU were included (pseudo = 42, non-pseudo = 182). Compared to non-pseudo, pseudo-patients were more often female (P = 0.0018) and had worse BL sagittal alignment, including T1PA (P = 0.02], C2-C7 SVA [P = 0.0002], and CrSVA-Hip [P = 0.004]. After 37 PSM pairs were generated, there was no significant difference in demographics, BL and 2Y alignment, or operative/procedural variables. PSM pairs did not report any significantly different PROs at BL. Consistently, at 2Y, there were no significant differences in PROs, including SRS function [3.9(0.2) vs 3.7(0.2), P = 0.44], pain [4.0 (0.2) vs. 3.57 (0.2), P = 0.12], and ODI [25.7 (5.2) vs 27.7 (3.7), P = 0.76]. There were no differences in 1Y (10.8% vs 10.8%, P > 0.99) and 2Y (13.2% vs 15.8%, P = 0.64) reoperation, PJK rate (2.6% vs 10.5%, P = 0.62), or implant failure (2.6% vs 10.5%, P = 0.37). Notably, only 2 patients (5.4%) had recurrent pseudarthrosis following revision. Kaplan-Meier curves indicated that patients undergoing intervention for pseudarthrosis had comparable overall reoperation-free survival (log-rank test, χ2 = 0.1975 and P = 0.66).

CONCLUSIONS

Patients undergoing revision for pseudarthrosis have comparable PROs and clinical outcomes as patients who never experienced pseudarthrosis. Recurrence of symptomatic pseudarthrosis was infrequent.

The Effect of Modifiable Risk Factors on Postoperative Complications in Lumbar Spine Fusions

STUDY DESIGN

Retrospective cohort study.

OBJECTIVES

The impact of modifiable risk factors (MRFs) on complications, costs, and readmission rates at 30, 90, and 180-days following lumbar spine fusion.

METHODS

Patients with lumbar spine fusions within the 2016-2017 Nationwide Readmissions Database (NRD). Patients were stratified by the following MRFs: Alcohol use, tobacco/nicotine use, nutritional malnourishment, dyslipidemia, and primary hypertension. Differences in complications, non-elective readmission rates, costs, and length of stay were compared between MRFs and the non-MRF group. Statistical analysis was conducted using Tukey multiple comparisons of means, 1-way ANOVA, Wald testing, unpaired Welch 2-sample t-tests, multivariate analysis, and predictive modeling.

RESULTS

The final analysis included 297,579 lumbar fusion patients. At 30 and 90 days, patients with nutritional malnutrition, dyslipidemia, and primary hypertension had significantly greater readmission rates than patients without MRFs (all P<0.01). At 180-days, all MRFs had significantly greater readmission rates than the non-MRF group (all P<0.001). Dyslipidemia demonstrated significantly greater rates of myocardial infarction at 90 days compared to all groups (all P<0.02). Nutritional malnutrition was associated with a significantly greater mortality rate than primary hypertension, non-MRF, and tobacco/nicotine use at 90 days (P<0.001) and only tobacco/nicotine use at 180 days (P=0.007). Predictive modeling showed increases of 0.77%, 1.70%, and 2.44% risk of readmission at 30, 90, and 180-days respectively per additional MRF (all P<0.001).

CONCLUSIONS

These findings highlight the negative impact each MRF has on patients following lumbar spinal fusion. Further longitudinal research is necessary to comprehensively characterize the effects of various MRFs on spine surgery outcomes.

An alternative method to evaluate lumbar interbody fusion status focusing on position change of screw-rod constructs

OBJECTIVES

The evaluation of lumbar interbody fusion status is generally subjective and may differ among raters. The authors examined whether the assessment of position change of screw-rod constructs could be an alternative method for the evaluation of fusion status.

METHODS

Sixty-three patients undergoing lumbar interbody single-level fusion were retrospectively reviewed. Three-dimensional images of screw-rod constructs were created from baseline CT examination on the day after surgery and follow-up CT examinations (3-5 months, 6-11 months, and ≥ 12 months) and superposed, with position change of screw-rod constructs being evaluated by the distance between the 3-dimensional images at baseline and follow-up. The evaluation was repeated twice to confirm the reproducibility. Fusion status on follow-up CT examinations was assessed by three raters, where inter-rater reliability was evaluated with Fleiss' kappa. The results of the fusion status were classified into fusion and incomplete fusion groups in each timing of follow-up CT examinations, where the amount of position change was compared between the two groups.

RESULTS

The evaluation of position change was completely reproducible. The Fleiss' kappa (agreements) was 0.481 (69.4%). The medians of the amount of position change in fusion and incomplete fusion groups were 0.134 mm and 0.158 mm at 3-5 months (p = 0.21), 0.160 mm and 0.190 mm at 6-11 months (p = 0.02), and 0.156 mm and 0.314 mm at ≥ 12 months (p = 0.004).

CONCLUSIONS

The assessment of position change of screw-rod constructs at 6 months or more after surgery can be an alternative method for evaluating lumbar interbody fusion status.

KEY POINTS

• Lumbar interbody fusion status (satisfactory, incomplete, or failed) is associated with the quantification of position change of screw-rod in this study. • Reference values for the evaluation of position change in identifying interbody fusion status are provided. • Position change of screw-rod could be a supportive method for evaluating interbody fusion status.

Revision lumbar fusions have higher rates of reoperation and result in worse clinical outcomes compared to primary lumbar fusions

BACKGROUND CONTEXT

Indications for revision lumbar fusion are variable, but include recurrent stenosis (RS), adjacent segment disease (ASD), and pseudarthrosis. The efficacy of revision lumbar fusion has been well established, but their outcomes compared to primary procedures is not well documented.

PURPOSE

The purpose of this study was to compares surgical and clinical outcomes between (1) revision and primary lumbar fusion, (2) revision lumbar fusion based on indication (ASD, pseudarthrosis, or RS), and (3) revision lumbar fusion based on whether the index procedure included an isolated decompression or decompression with fusion.

STUDY DESIGN/SETTING

Retrospective single-institution cohort study.

PATIENT SAMPLE

Four thousand six hundred seventy-one consecutive lumbar fusions from 2011 to 2021, of which 892 (23.6%) were revision procedures. The indication for revision procedures included 502 (56.3%) for ASD, 153 (17.2%) for pseudarthrosis, and 237 (26.6%) for RS. Of the 892 revision procedures, 694 (77.8%) underwent an index fusion while 198 (22.2%) underwent an index decompression without fusion.

OUTCOME MEASURES

Hospital readmissions, all-cause reoperation, need for subsequent revision and patient reported outcome measures (PROMs) at baseline, 3-months postoperatively, and 1-year postoperatively, including the Mental Health Component score (MCS-12) and Physical Health Component score (PCS-12) of the Short Form 12 survey, the Oswestry Disability Index (ODI), and the Visual Analog Scale (VAS) for Back and Leg pain.

METHODS

Patient demographics, comorbidities, surgical characteristics, and outcomes were collected from electronic medical records. Twenty-eight percent of patients had preoperative and postoperative PROMs. A delta PROM score was calculated for the 3-month and 1-year postoperative timepoints, which was the change from the preoperative to postoperative value. Univariate comparisons were performed to compare revision fusions to primary fusions. Multivariate logistic regression was performed for all-cause reoperation and subsequent revision surgery, while multivariate linear regression was performed for ∆PROMs at 3-months and 1-year. Revision procedures were then separately regrouped based on indication for revision fusion and whether they underwent a fusion for their index procedure. Univariate comparisons and multivariate linear regressions for ∆PROMs were then repeated based on the new groupings.

RESULTS

There was no difference in hospital readmission rate (5.38% vs. 4.60%, p=.372) or length of stay (4.10 days vs. 3.94 days, p=.129) between revision and primary lumbar fusion, but revision fusions had a higher rate of all-cause reoperation (16.1% vs. 11.2%, p<.001) and subsequent revision (13.7% vs. 9.71%, p=.001), which was confirmed on multivariate logistic regression (Odds Ratio (OR): 1.42, p=.001 and OR: 1.37, p=.007, respectively). On multivariate analysis, a revision procedure was an independent risk factor for worse improvement ∆ODI, ∆VAS Back, ∆VAS Leg, and ∆PCS-12 and 1-year postoperatively. Regardless of the indication for revision lumbar fusion, patients significantly improved in the 3-month and 1-year postoperative PCS-12, ODI, VAS Back, and VAS Leg, with the exception of the 3-month PCS-12 for pseudarthrosis (p=.620). Patients undergoing revision for ASD had significantly worse 1-year postoperative PCS-12 (32.3 vs. Pseudarthrosis: 35.6 and RS: 37.0, p=.026), but there were no differences in ∆PROMs. There was no difference in hospital readmission, all-cause reoperation, or subsequent revision based on whether a patient had an index lumbar fusion or isolated decompression. Multivariate linear regression analysis found that a surgical indication of pseudarthrosis was a significant predictor of decreased improvement in 3-month ∆VAS Leg (ref: ASD, β=2.26, p=.036), but having an index fusion did not significantly predict worse improvement in ∆PROMs when compared to isolated decompressions.

CONCLUSIONS

Revision lumbar fusions had a higher rate of reoperation and subsequent revision surgery when compared to primary lumbar fusions, but there were no difference in hospital readmission rates. Patients undergoing revision lumbar fusion experience improvements in all patient reported outcome measures, but their baseline, postoperative, and magnitude of improvement are worse than primary procedures. Regardless of whether the lumbar fusion is a primary or revision procedure, all patients have significant improvements in pain, disability and physical function. Further, the indication for the revision procedure is not correlated with the expected magnitude of improvement in patient reported outcomes. Finally, no differences in baseline, postoperative, and ∆PROMs for revision fusions were identified when stratifying by whether the patient had an index decompression or fusion.

Clinical relevance of occult infections in spinal pseudarthrosis revision

Background

Occult infections in spinal pseudarthrosis revisions have been reported in the literature, but the relevance of such an infection on patient outcomes is unknown. We aimed to elucidate clinical outcomes and re-revision risks between patients with and without occult infections in spinal revision surgery for pseudarthrosis.

Methods

In this matched case-control study, we identified 128 patients who underwent thoracolumbar revision surgery from 2014–2019 for pseudarthrosis of the spine. Among them, 13 (10.2%) revealed an occult infection (defined by at least two positive intraoperative tissue samples with the same pathogen), and nine of these 13 were available for follow-up. We selected 18 of the 115 controls using a 2:1 fuzzy matching based on fusion length and length of follow-up. The patients were followed up to assess subsequent re-revision surgeries and the following postoperative patient-reported outcome measures (PROMs): overall satisfaction, Oswestry Disability Index, 5-level EQ-5D, and Short Form 36.

Results

Patient characteristics, surgical data, and length of follow-up were equal between both study groups. The rate of re-revision free survival after the initial pseudarthrosis revision surgery was higher in the occult infection group (77.8%) than the non-infectious controls (44.4%), although not significantly (0.22). The total number of re-revision surgeries, including re-re-revisions, was thirteen (in ten patients) in the control and two (in two patients) in the occult infection group (p = 0.08) after a median follow-up of 24 months (range 13-75). Four cases in the control group underwent re-revision for pseudarthrosis compared to none in the infected group. Satisfactory scores were recorded in all PROMs, with similar scores between the two groups.

Conclusions

The presence of an occult infection accompanying spinal pseudarthrosis revision was not inferior to non-infected pseudarthrosis revisions in a matched, small sample size cohort study. This may be explained due to the possibility of targeted treatment of the identified cause of pseudarthrosis.

Clinical and Cost-Effectiveness of Lumbar Interbody Fusion Using Tritanium Posterolateral Cage (vs. Propensity-Matched Cohort of PEEK Cage)

Introduction

Surgical management of degenerative lumbar spine disorders is effective at improving patient pain, disability, and quality of life; however, obtaining a durable posterolateral fusion after decompression remains a challenge. Interbody fusion technologies are viable means of improving fusion rates in the lumbar spine, specifically various graft materials including autograft, structural allograft, titanium, and polyether ether ketone. This study assesses the effectiveness of Tritanium posterolateral cage in the treatment of degenerative disk disease.

Methods

Nearest-neighbor 1:1 matched control transforaminal lumbar interbody fusion with PEEK vs. Tritanium posterior lumbar (PL) cage interbody fusion patients were identified using propensity scoring from patients that underwent elective surgery for degenerative disk diseases. Line graphs were generated to compare the trajectories of improvement in patient-reported outcomes (PROs) from baseline to 3 and 12 months postoperatively. The nominal data were compared via the χ² test, while the continuous data were compared via Student's t-test.

Results

The two groups had no difference regarding either the 3- or 12-month Euro-Qol-5D (EQ-5D), numeric rating scale (NRS) leg pain, and NRS back pain; however, the Tritanium interbody cage group had better Oswestry Disability Index (ODI) scores compared to the control group of the PEEK interbody cage at both 3 and 12 months (p=0.013 and 0.048).

Conclusions

Our results indicate the Tritanium cage is an effective alternative to the previously used PEEK cage in terms of PROs, surgical safety, and radiological parameters of surgical success. The Tritanium cohort showed better ODI scores, higher fusion rates, lower subsidence, and lower indirect costs associated with surgical management, when compared to the propensity-matched PEEK cohort.

Comparison of 3D-printed titanium-alloy, standard titanium-alloy, and PEEK interbody spacers in an ovine model

BACKGROUND CONTEXT

Osseointegration is a pivotal process in achieving a rigid fusion and ultimately a successful clinical outcome following interbody fusion surgery. Advancements in 3D printing technology permit commonly used titanium interbody spacers to be designed with unique architectures, such as a highly interconnected and specific porous structure that mimics the architecture of trabecular bone. Interbody implants with a microscale surface roughness and biomimetic porosity may improve bony ongrowth and ingrowth compared to traditional materials.

PURPOSE

The purpose of this study was to compare the osseointegration of lumbar interbody fusion devices composed of surgical-grade polyetheretherketone (PEEK), titanium-alloy (TAV), and 3D-printed porous, biomimetic TAV (3DP) using an in vivo ovine model.

STUDY DESIGN

In Vivo Preclinical Animal Study METHODS: Eighteen sheep underwent two-level lateral lumbar interbody fusion randomized with either 3DP, PEEK, or TAV interbody spacers (n=6 levels for each spacer per time point). Postoperative time points were 6 and 12 weeks. Microcomputed tomography and histomorphometry were used to quantify bone volume (BV) within the spacers (ingrowth) and the surface bone apposition ratio (BAR) (ongrowth), respectively.

RESULTS

The 3DP-treatment group demonstrated significantly higher BV than the PEEK and TAV groups at 6 weeks (77.3±44.1 mm³, 116.9±43.0 mm³, and 108.7±15.2 mm³, respectively) (p<.05). At 12 weeks, there were no BV differences between groups (p>.05). BV increased in all groups from the 6- to 12-week time points (p<.05). At both time points, the 3DP-treated group (6w: 23.6±10.9%; 12w: 36.5±10.9%) had significantly greater BAR than the PEEK (6w: 8.6±2.1%; 12w: 14.0±5.0%) and TAV (6w: 6.0±5.7%; 12w: 4.1±3.3%) groups (p<.05).

CONCLUSIONS

3DP interbody spacers facilitated greater total bony ingrowth at 6 weeks, and greater bony ongrowth postoperatively at both 6 and 12 weeks, in comparison to solid PEEK and TAV implants.

CLINICAL SIGNIFICANCE

Based on these findings, the 3DP spacers may be a reasonable alternative to traditional PEEK and TAV spacers in various clinical applications of interbody fusion.

Radiographic and clinical outcomes of silicate-substituted calcium phosphate (SiCaP) bone grafts in spinal fusion: Systematic review and meta-analysis

Pseudarthrosis continues to affect a nontrivial proportion of spine fusion patients. Given its ties to poorer patient outcomes and high reoperation rates, there remains great interest in interventions aimed at reducing the rates of nonunion. Recently, silicate-substituted calcium phosphate (SiCaP) bone grafts have been suggested to improve fusion rates, yet there exists no systematic review of the body of evidence for SiCaP grafts. Here, we present the first such review along with a meta-analysis of the effect of SiCaP bone grafts on fusion rates. Using the PubMed, Embase, and Web of Science databases, we queried the English-language literature for all studies examining the effect of SiCaPs on spinal fusion. Primary endpoints were: 1) radiographic fusion rate at last follow-up and 2) postoperative improvements in Visual Analog Scale (VAS) pain scores and Oswestry Disability Index (ODI) at last follow-up. Meta-analyses were performed for each endpoint using random effects. Ten articles (694 patients treated with SiCaP bone grafts) were included. Among SiCaP-treated patients, 93% achieved radiographic fusion (range: 79-100%), with comparable rates across subgroups. Meta-analysis of the three randomized controlled trials demonstrated no difference in fusion rates between SiCaP-treated patients and patients receiving grafts with recombinant human bone morphogenetic protein-2 (rhBMP-2) (OR: 1.11; p = 0.83). Patients treated with SiCaP bone grafts experienced significant improvements in VAS back pain (-3.3 points), VAS leg pain (-4.8 points), and ODI (-31.6 points) by last follow-up (p < 0.001 for each). Additional high-quality research is needed to evaluate the relative cost-effectiveness of SiCaP bone grafts in spinal fusion.

Optimizing the Spinal Interbody Implant: Current Advances in Material Modification and Surface Treatment Technologies

PURPOSE OF REVIEW

Interbody implants allow for fusion of the anterior column of the spine between vertebral body endplates. As rates of spinal fusion surgery have increased over the past several years, significant research has been devoted to optimizing both the mechanical and biologic properties of the interbody implant in order to promote bony fusion. The first interbody implants used decades ago were fashioned from cortical autograft. Currently, titanium alloy and polyetheretherketone (PEEK) are the most widely used and studied materials for this purpose. This review focuses on recent innovations in material modification and surface treatment techniques for both titanium and PEEK implants to maximize fusion rates in spinal surgery.

RECENT FINDINGS

Titanium has an elastic modulus much higher than native bone and however has better osseointegrative properties than PEEK. PEEK, however, has an elastic modulus closer to that of bone without any of the advantageous biologic properties that titanium has. Increasing porosity and surface roughness of titanium implants have been shown to improve the mechanical properties of titanium implants, while the biologic properties of PEEK have been enhanced using surface coating technology, either with titanium or with hydroxyapatite (HA). Techniques such as increasing porosity, surface roughening, and surface coating are just some of the recent innovations aimed at optimizing both mechanical and biologic properties of interbody implants to promote spinal fusion. The future of interbody implant design will rely on continued improvements of PEEK and titanium implants as well as exploring new implant materials altogether.

The effect of bioactive glasses on spinal fusion: A cross-disciplinary systematic review and meta-analysis of the preclinical and clinical data

Pseudarthrosis following spinal fusion is correlated with poorer patient outcomes and consequently is an area of continued interest within spinal research. Recently, bioactive glasses have been proposed as a means of augmenting fusion rates. Here, we present the first systematic review and meta-analysis of the existing preclinical and clinical literature on the effect of bioactive glasses on spinal fusion. Using the MEDLINE, Embase, and Web of Science databases, we queried all publications in the English-language literature examining the effect of bioactive glasses on spinal fusion. The primary endpoint was fusion rate at last follow-up and the secondary endpoint for clinical studies was the rate of deep wound infection. Random-effects meta-analyses were performed independently for the preclinical and clinical data. Twelve preclinical studies (267 animals) and 12 clinical studies (396 patients) evaluating a total of twelve unique bioactive glass formulations were included. Across clinical studies, fusion was seen in 84% treated with bioactive glass. On sub-analysis, fusion rates were similar for standalone autograft (91.6%) and bioactive glass-local autograft mixtures (89.6%). Standalone bioactive glass substrates produced inferior fusion rates relative to autograft alone (33.6% vs. 98.8%; OR 0.01, p < 0.02). Rates of deep wound infection did not differ between the bioactive glass and autograft groups (3.1%). The preclinical data similarly showed comparable rates of fusion between autograft and bioactive glass-treated animals. The available data suggest that bioactive glass-autograft mixtures confer similar rates of spinal fusion relative to standalone autograft without altering the risk of deep wound infection.

The effect of electrical stimulation therapies on spinal fusion: a cross-disciplinary systematic review and meta-analysis of the preclinical and clinical data

OBJECTIVE

Nonunion is a common complication of spinal fusion surgeries. Electrical stimulation technologies (ESTs)-namely, direct current stimulation (DCS), capacitive coupling stimulation (CCS), and inductive coupling stimulation (ICS)-have been suggested to improve fusion rates. However, the evidence to support their use is based solely on small trials. Here, the authors report the results of meta-analyses of the preclinical and clinical data from the literature to provide estimates of the overall effect of these therapies at large and in subgroups.

METHODS

A systematic review of the English-language literature was performed using PubMed, Embase, and Web of Science databases. The query of these databases was designed to include all preclinical and clinical studies examining ESTs for spinal fusion. The primary endpoint was the fusion rate at the last follow-up. Meta-analyses were performed using a Freeman-Tukey double arcsine transformation followed by random-effects modeling.

RESULTS

A total of 33 articles (17 preclinical, 16 clinical) were identified, of which 11 preclinical studies (257 animals) and 13 clinical studies (2144 patients) were included in the meta-analysis. Among preclinical studies, the mean fusion rates were higher among EST-treated animals (OR 4.79, p < 0.001). Clinical studies similarly showed ESTs to increase fusion rates (OR 2.26, p < 0.001). Of EST modalities, only DCS improved fusion rates in both preclinical (OR 5.64, p < 0.001) and clinical (OR 2.13, p = 0.03) populations; ICS improved fusion in clinical studies only (OR 2.45, p = 0.014). CCS was not effective at increasing fusion, although only one clinical study was identified. A subanalysis of the clinical studies found that ESTs increased fusion rates in the following populations: patients with difficult-to-fuse spines, those who smoke, and those who underwent multilevel fusions.

CONCLUSIONS

The authors found that electrical stimulation devices may produce clinically significant increases in arthrodesis rates among patients undergoing spinal fusion. They also found that the pro-arthrodesis effects seen in preclinical studies are also found in clinical populations, suggesting that findings in animal studies are translatable. Additional research is needed to analyze the cost-effectiveness of these devices.

Analysis of single-position for revision surgery using lateral interbody fusion and pedicle screw fixation: feasibility and perioperative results

Background

To analyze perioperative and radiographic outcomes following revision surgery using lateral lumbar interbody fusion (LLIF) performed entirely in the lateral position. Traditionally, patients undergoing interbody fusion in the lateral decubitus position are placed prone for pedicle screw fixation. However prone positioning carries known risks and may increase surgical time due to the need to re-drape and reposition. Little is published regarding revision surgery in a single position.

Methods

Sixteen patients over the age of 18 with degenerative lumbar pathology who underwent a revision of previous lumbar fusion using interbody fusion via lateral access and revision of posterior instrumentation from a single surgeon met inclusion criteria. Patients who underwent combined procedures requiring repositioning or had inadequate preoperative imaging were excluded. Patients remained in the lateral decubitus position for the entirety of the procedure including interbody placement, revision of prior instrumentation, and pedicle screw fixation. Demographics, surgical details, and perioperative outcomes were reported.

Results

The mean operative time was 211 minutes for all cases, 161 minutes for single-level procedures and 296 minutes for two-level procedures. Mean estimated blood loss was 206 cc. The mean patient age was 66, 70% of which were male. The mean body mass index (BMI) was 27.4 and Charleson Comorbidity Index (CCI) was 3. All cases were performed on the lumbar spine (T12/L1-L4/L5), with the majority of procedures performed at the L2/3 level (44%). The mean pelvic incidence (PI) was 60 degrees (range, 41-71 degrees) with mean preoperative PI/lumbar lordosis (LL) mismatch of 23.9 degrees. Mean postoperative PI/LL mismatch was 12 degrees.

Conclusions

Revision surgery in the lateral position is feasible with complication rates comparable to published literature. The need to reposition is eliminated and single position surgery reduces operative time.

Allogenic Stem Cells in Spinal Fusion: A Systematic Review

STUDY DESIGN

Systematic review.

OBJECTIVES

To review, critically appraise, and synthesize evidence on the use of allogenic stem cell products for spine fusion compared with other bone graft materials.

METHODS

Systematic searches of PubMed/MEDLINE, through October 31, 2018 and of EMBASE and ClinicalTrials.gov through April 13, 2018 were conducted for literature comparing allogenic stem cell sources for fusion in the lumbar or cervical spine with other fusion methods. In the absence of comparative studies, case series of ≥10 patients were considered.

RESULTS

From 382 potentially relevant citations identified, 6 publications on lumbar fusion and 5 on cervical fusion met the inclusion criteria. For lumbar arthrodesis, mean Oswestry Disability Index (ODI), visual analogue scale (VAS) pain score, and fusion rates were similar for anterior lumbar interbody fusion (ALIF) using allogenic multipotent adult progenitor cells (Map3) versus recombinant human bone morphogenetic protein-2 (rhBMP-2) in the one comparative lumbar study (90% vs 92%). Across case series of allogenic stem cell products, function and pain were improved relative to baseline and fusion occurred in ≥90% of patients at ≥12 months. For cervical arthrodesis across case series, stem cell products improved function and pain compared with baseline at various time frames. In a retrospective cohort study fusion rates were not statistically different for Osteocel compared with Vertigraft allograft (88% vs 95%). Fusion rates varied across time frames and intervention products in case series.

CONCLUSIONS

The overall quality (strength) of evidence of effectiveness and safety of allogenic stem cells products for lumbar and cervical arthrodesis was very low, meaning that we have very little confidence that the effects seen are reflective of the true effects.

Health-related quality of life outcomes in complex adult spinal deformity surgery

OBJECTIVE Significant health-related quality of life (HRQOL) benefits have been observed for patients undergoing primary and revision adult spinal deformity (ASD) surgery. The purpose of this study was to report changes in HRQOL measures in a consecutive series of patients undergoing complex spinal reconstructive surgery, using Scoli-RISK-1 (SR-1) inclusion criteria. METHODS This was a single-center, retrospective cohort study. The SR-1 inclusion criteria were used to define patients with complex ASD treated between June 1, 2009, and June 1, 2011. Standard preoperative and perioperative data were collected, including the Scoliosis Research Society (SRS)-22r instrument. The HRQOL changes were evaluated at a minimum 2-year follow-up. Standardized forms were used to collect surgery-related complications data for all patients. Complications were defined as minor, transient major, or permanent major. Patients who achieved a minimum 2-year follow-up were included in the analysis. RESULTS Eighty-four patients meeting SR-1 criteria were identified. Baseline demographic and surgical data were available for 74/84 (88%) patients. Forty-seven of 74 (64%) patients met the additional HRQOL criteria with a minimum 2-year follow-up (mean follow-up 3.4 years, range 2-6.5 years). Twenty-one percent of patients underwent posterior fusion only, 40% of patients had a posterior column osteotomy, and 38% had a 3-column osteotomy. Seventy-five percent of patients underwent a revision procedure. Significant improvements were observed in all SRS-22r domains: Pain: +0.8 (p < 0.001); Self-Image: +1.4 (p < 0.001); Function: +0.46 (p < 0.001); Satisfaction: +1.6 (p < 0.001); and Mental Health: +0.28 (p = 0.04). With the exception of Mental Health, more than 50% of patients achieved a minimum clinically important difference (MCID) in SRS-22r domain scores (Mental Health: 20/47, 42.6%). A total of 65 complications occurred in 31 patients. This includes 29.8% (14/47) of patients who suffered a major complication and 17% (8/47) who suffered a postoperative neurological deficit, most commonly at the root level (10.6%, 5/47). Of the 8 patients who suffered a neurological deficit, 1 (13%) was able to achieve MCID in the SRS Function domain. CONCLUSIONS The majority of patients experienced clinically relevant improvement in SRS-22r HRQOL scores after complex ASD surgery. The greatest improvements were seen in the SRS Pain and SRS Self-Image domains. Although 30% of patients suffered a major or permanent complication, benefits from surgery were still attained. Patients sustaining a neurological deficit or major complication were unlikely to achieve HRQOL improvements meeting or exceeding MCID for the SRS Function domain.

Predicting Postoperative Morbidity and Readmission for Revision Posterior Lumbar Fusion

STUDY DESIGN

Retrospective cohort study.

OBJECTIVE

The primary aim of this study was to determine the incidence and risk factors for 30-day adverse events after revision posterior lumbar fusion. The secondary aim was to determine the incidence and risk factors for 30-day readmission after revision posterior lumbar fusion.

SUMMARY OF BACKGROUND DATA

The need for revision of a lumbar fusion is an unfortunate occurrence, and there is little known about specific risk factors for morbidity and readmission after this procedure. The purpose of this study is to use a large, national sample to identify patient and operative factors that may contribute to the development of these adverse outcomes.

METHODS

The American College of Surgeons National Surgical Quality Improvement Program (ACS-NSQIP) database was used to identify patients undergoing revision posterior lumbar fusion from 2005 to 2013. Patient characteristics were tested for association with any adverse event (AAE), severe adverse events (SAEs), minor adverse events (MAEs), and readmission within 30 days postoperatively using multivariate analysis.

RESULTS

Of the 1287 patients identified, 8.2% had an AAE, 5.6% had an SAE, and 3.2% had an MAE. AAE was independently associated with American Society of Anesthesiologists (ASA) classification ≥3 and operative time ≥310 minutes (P<0.05 for each). SAEs were associated with only ASA classification ≥3 (P=0.047). MAEs were associated with insulin-dependent diabetes, operative time ≥310 minutes, and 3 or more levels of fusion (P<0.05 for all).Sixty-five patients (5.6%) were readmitted. On multivariate analysis, body mass index (BMI) 25-30, BMI 30-35, BMI≥35, ASA classification ≥3, insulin-dependent diabetes, a 2-level fusion, and 3 or more levels of fusion were associated with readmission (P<0.05 for all).

CONCLUSIONS

In general, longer, more extensive procedures on sicker patients were associated with increased risk of postoperative complications and readmission.

Impact of Surgical Approach on Clinical Outcomes in the Treatment of Lumbar Pseudarthrosis

Study Design Retrospective comparative cohort. Objective Pseudarthrosis following fusion for degenerative lumbar spine pathologies remains a substantial problem. Current data shows that patients who develop a pseudarthrosis have suboptimal outcomes. This study evaluates if treatment of pseudarthrosis can be affected by surgical approach. Methods Medical records of 63 female and 65 male patients (mean age 50.37) who were treated for nonunion following lumbar fusion were reviewed. Sixty patients underwent posterolateral fusion (PSF), 18 underwent PSF with transforaminal interbody fusion (TLIF), 32 underwent anterior and posterior spinal fusion (AP), and 24 underwent anterior lumbar interbody fusion (ALIF). Results Significant differences between the treatment groups were observed in length of stay (p = 0.000), blood loss (p = 0.000), and operative time (p = 0.000). In the AP fusion group, minimal clinically important difference (MCID) was reached in 47% of patients for back pain, 28% for leg pain, and 28% for Oswestry Disability Index (ODI). PSF had the highest percentage of patients reaching MCID for Short Form-36 (SF-36) physical composite score at 25%. ALIF and TLIF subgroups reached MCID for ODI in 17% of patients. Linear regression analysis showed that type of surgical approach did not impact change in ODI scores. Conclusion Although not statistically significant, the AP fusion group reached MCID more frequently in all outcomes except SF-36 Physical Component Summary. All surgical approaches examined for treatment of lumbar pseudarthrosis resulted in only poor to modest improvement in ODI. This result further emphasizes the importance of achieving a solid fusion with the index surgery.

The use of bone morphogenetic proteins (BMP) and pseudarthrosis, a literature review

Bone morphogenetic proteins (BMP) are multi-functional growth factors to promote bone healing with the proposal of less morbidity compared to the usual methods of bone graft harvest. Pseudoarthrosis occur when the fusion attempt fails, a solid fusion is not achieved, or there is motion across the segment leading to it, and it can be clinically symptomatic as pain, deformity, neurocompression, or hardware failure. BMPs are used at spinal fusion as a tool for the treatment of degenerative, traumatic, neoplastic and infectious conditions of the spine. This review shows that the use of BMPS is effective and secure when compared with iliac crest bone graft (ICGB); however, depending of the location of usage (cervical spine, lumbar spine or sacrum) and the medical status of the patient (presence of comorbidities, tobacco usage), it is more likely to exhibit complications. Therefore, the use of these proteins must be an informed decision of patient and physician preferences.

Risk factors for revision surgery following primary adult spinal deformity surgery in patients 65 years and older

OBJECTIVE Surgical correction of adult spinal deformity (ASD) is a complex undertaking with high revision rates. The elderly population is poorly studied with regard to revision surgery, yet senior citizens constitute a rapidly expanding surgical demographic. Previous studies aimed at elucidating appropriate risk factors for revision surgery have been limited by small cohort sizes. The purpose of this study was to assess factors that modify the risk of revision surgery in elderly patients with ASD. METHODS The PearlDiver database (2005-2012) was used to determine revision rates in elderly ASD patients treated with a primary thoracolumbar posterolateral fusion of 8 or more levels. Analyzed risk factors included demographics, comorbid conditions, and surgical factors. Significant univariate predictors were further analyzed with multivariate analysis. The causes of revision at each year of follow-up were determined. RESULTS A total of 2293 patients who had been treated with posterolateral fusion of 8 or more levels were identified. At the 1-year follow-up, 241 (10.5%) patients had been treated with revision surgery, while 424 (18.5%) had revision surgery within 5 years. On univariate analysis, obesity was found to be a significant predictor of revision surgery at 1 year, while bone morphogenetic protein (BMP) use was found to significantly decrease revision surgery at 4 and 5 years of followup. Diabetes mellitus, osteoporosis, and smoking history were all significant univariate predictors of increased revision risk at multiple years of follow-up. Multivariate analysis at 5 years of follow-up revealed that osteoporosis (OR 1.98, 95% CI 1.60-2.46, p < 0.0001) and BMP use (OR 0.70, 95% CI 0.56-0.88, p = 0.002) were significantly associated with an increased and decreased revision risk, respectively. Smoking history trended toward significance (OR 1.37, 95% CI 1.10-1.70, p = 0.005). Instrument failure was consistently the most commonly cited reason for revision. Five years following surgery, it was estimated that the cohort had 68.8% survivorship. CONCLUSIONS For elderly patients with ASD, osteoporosis increases the risk of revision surgery, while BMP use decreases the risk. Other comorbidities were not found to be significant predictors of long-term revision rates. It is expected that within 5 years following the index procedure, over 30% of patients will require revision surgery.

Spine interbody implants: material selection and modification, functionalization and bioactivation of surfaces to improve osseointegration

The clinical outcome of lumbar spinal fusion is correlated with achievement of bony fusion. Improving interbody implant bone on-growth and in-growth may enhance fusion, limiting pseudoarthrosis, stress shielding, subsidence and implant failure. Polyetheretherketone (PEEK) and titanium (Ti) are commonly selected for interbody spacer construction. Although these materials have desirable biocompatibility and mechanical properties, they require further modification to support osseointegration. Reports of extensive research on this topic are available in biomaterial-centric published reports; however, there are few clinical studies concerning surface modification of interbody spinal implants. The current article focuses on surface modifications aimed at fostering osseointegration from a clinician's point of view. Surface modification of Ti by creating rougher surfaces, modifying its surface topography (macro and nano), physical and chemical treatment and creating a porous material with high interconnectivity can improve its osseointegrative potential and bioactivity. Coating the surface with osteoconductive materials like hydroxyapatite (HA) can improve osseointegration. Because PEEK spacers are relatively inert, creating a composite by adding Ti or osteoconductive materials like HA can improve osseointegration. In addition, PEEK may be coated with Ti, effectively bio-activating the coating.

Fate of the adult revision spinal deformity patient: a single institution experience

STUDY DESIGN

Retrospective case series.

OBJECTIVE

The aim of this study was to determine the revision rates for all revision spinal deformity (SD) surgical procedures performed at a single center and to investigate the changes in measures of HRQL in these patients.

SUMMARY OF BACKGROUND DATA

Reported revision rates for primary adult spinal fusion surgical procedures have been in the range of 9% to 45%, but to our knowledge, the revision rate after revision SD surgery has not been reported. The reported improvements in health-related quality of life measures after revision SD surgery have also been quite modest.

METHODS

Four hundred fifty-five consecutive adult revision SD surgical procedures (1995-2008) were identified and the records were reviewed to determine the reason for and timing to any additional operation(s). Scoliosis Research Society (SRS) Outcome scores were recorded at the first visit and at planned follow-up visits.

RESULTS

Ninety-four of 455 patients underwent further surgical procedures for a revision rate of 21%. Two-year follow-up was available for 74 (78%) of these patients (mean follow-up, 6.0 yr; range, 2.4-12.6; sex: F = 61, M = 13; mean age, 53 yr; range, 21-78). The most common causes of revision surgery were pseudarthrosis (N = 23, 31%), implant prominence/pain (N = 15, 20%), adjacent segment disease (N = 14, 19%), and infection (N = 10, 14%). Twenty-five (27%) patients underwent more than one revision procedure. SRS outcome scores were available for 50 (68%) patients, at an average follow-up of 4.9 years (range, 2-11.4). The mean improvements in the SRS outcome measures were as follows: pain, 0.74 (P < 0.001); self-image, 0.8 (P < 0.001); function, 0.5 (P < 0.001); satisfaction, 1.2 (P < 0.001); and mental health, 0.3 (P = 0.012).

CONCLUSION

The rate of revision after revision SD surgery was 21%, most commonly due to pseudarthrosis, adjacent segment disease, infection, and implant prominence/pain. However, significant improvements in SRS outcome scores were still observed in those patients requiring additional revision procedures.

Cancer After Spinal Fusion

BACKGROUND:

Bone morphogenetic protein (BMP) is used in tens of thousands of spinal fusions each year. A trial evaluating a high-dose BMP formulation demonstrated that its use may be associated with an increased risk of cancer.

OBJECTIVE:

To evaluate whether BMP, as commonly used today, is associated with an increased risk of cancer or benign tumors.

METHODS:

We performed a retrospective study using the Thomson Reuter MarketScan database. We retained all patients who had no previous diagnosis of cancer or benign tumor and had at least 2 years of uninterrupted enrollment in the database before and after their operations. A propensity score--matched cohort was created to ensure greater covariate balance between treatment groups.

RESULTS:

Within the propensity score--matched cohort (n = 4698), BMP-exposed patients had a nonsignificant increase in the rate of cancer diagnosis (9.37% vs 7.92%; P = .08). After adjustment for covariates, BMP exposure was associated with a 31% increased risk of benign tumor diagnosis (odds ratio, 1.31; 95% confidence interval, 1.02-1.68; P &lt; .05). When the benign tumor diagnoses were stratified by organ type, BMP patients had significantly more diagnoses of benign nervous system tumors (0.81% vs 0.34%; P = .03), and within this group, benign tumors of the spinal meninges were much more common in the BMP-treated group (0.13% vs 0.02%; P = .002).

CONCLUSION:

The results of this large, independent, propensity-matched study suggest that the use of BMP in lumbar fusions is associated with a significantly higher rate of benign neoplasms but not malignancies.

Disparities in the outcomes of lumbar spinal stenosis surgery based on insurance status

STUDY DESIGN

Retrospective cohort study using Thomson Reuter's MarketScan database.

OBJECTIVE

To evaluate the extent to which Medicaid versus commercial insurance status affects outcomes after lumbar stenosis surgery.

SUMMARY OF BACKGROUND DATA

The Affordable Care Act aims to expand health insurance and to help narrow existing health care disparities. Medicaid patients have previously been noted to be at an increased risk for impaired access to health care. Conversely, those with commercial insurance may be subject to overtreatment. We examine the surgical treatment of low back pain as an example that has raised significant public health concerns.

METHODS

A total of 28,462 patients, ages 18 and older, were identified who had undergone laminectomy or fusion for spinal stenosis between 2000 and 2009. Patients were characterized by baseline demographic information, comorbidity burden, and type of insurance (Medicaid vs. commercial insurance). Multivariate analysis was performed comparing the relative effect of insurance status on reoperation rates, timing and type of reoperations, postoperative complications, and total postoperative health resource use.

RESULTS

Medicaid patients had similar reoperation rates to commercially insured patients at 1 year (4.60% vs. 5.42%, P = .38); but had significantly lower reoperation rates at 2 (7.22% vs. 10.30%; adjusted odds ratio [aOR] = 0.661; 95% confidence interval [CI], 0.533-0.820; P = .0002) and more than 2 years (13.92% vs. 16.89%; aOR = 0.722; 95% CI, 0.612-0.851; P <.0001). Medicaid patients were particularly less likely to undergo fusion as a reoperation (aOR = 0.478; 95% CI, 0.377-0.606; P < 0001). Medicaid patients had greater health care resource utilization as measured by hospital days, outpatient services and medications prescribed; however, commercially insured patients had significantly higher overall health utilization costs at 1 and 2 years.

CONCLUSION

There are insurance disparities that affect important surgical outcomes after initial surgery for spinal stenosis. Efforts for national health care reform should include explicit efforts to identify such system factors that will reduce current inequities in care.

LEVEL OF EVIDENCE

2.

Readmission rates after decompression surgery in patients with lumbar spinal stenosis among Medicare beneficiaries

STUDY DESIGN

Retrospective observational cohort analysis of administrative claims.

OBJECTIVE

Estimate readmission rates after spine stenosis decompression surgery in a 5% randomly selected sample of Medicare beneficiaries.

SUMMARY OF BACKGROUND DATA

Operative management of lumbar spinal stenosis has significant and measurable benefits compared with nonoperative care. Revision rates for lumbar decompression with and without fusion have been reported with significant variability. An understanding of readmission and reoperation rates informs decisions regarding the cost-effective management of lumbar stenosis.

METHODS

Patients were identified in 2005-2009 Medicare claims who had both a procedure code for decompression (03.09), and a diagnosis of lumbar spinal stenosis (724.02). Patients diagnosed with spondylolisthesis, and those receiving revision surgery or fusion of more than 3 segments were excluded. Kaplan-Meier product limit method was used to estimate univariate rates of readmission for fusion, decompression, or injection and Cox proportional hazards to examine whether fusion decreased the likelihood of readmission.

RESULTS

The overall 1-year readmission rate was slightly higher in patients undergoing fusion with decompression (9.7%) than patients who underwent decompression alone (7.2%, P = 0.03). Rates at 2 years were 14.6% and 12.5%, respectively. Patients receiving decompression with fusion were slightly younger and more likely female. Procedures performed during readmission were similar for the fusion and no fusion cohorts with 56% receiving fusion, 23% decompression, and 22% injection for pain management. Of the patients who were not readmitted, more than 25% of patients received outpatient injections for pain management during the 3-month quarter of their surgery and approximately 20% in the subsequent quarter.

CONCLUSION

Readmission rates for spinal stenosis decompression were approximately 8% to 10% per year. Fusion at the index procedure did not protect against subsequent readmission. Large databases can inform choice of surgical options by focusing examination on indications for surgery and reasons for readmission. Fusion along with decompression does not seem to impact readmission rates.

Assessment of the minimum clinically important difference in pain, disability, and quality of life after anterior cervical discectomy and fusion

Object

Treatment effectiveness following spine surgery is usually gauged with the help of patient-reported outcome (PRO) questionnaires. Although these questionnaires assess pain, disability, and general health state, their numerical scores lack direct, clinically significant meaning. Thus, the concept of minimum clinically important difference (MCID) has been introduced, which indicates the smallest change in an outcome measure that reflects clinically meaningful improvement to patients. The authors set out to determine anterior cervical discectomy and fusion (ACDF)–specific MCID values for the visual analog scale (VAS), Neck Disability Index (NDI), 12-Item Short-Form Health Survey (SF-12), and EQ-5D (the EuroQol health survey) in patients undergoing ACDF for cervical radiculopathy.

Methods

Data on 69 patients who underwent ACDF for cervical radiculopathy were collected in the authors' web-based, prospective registry during the study enrollment period. Patient-reported outcome questionnaires (VAS–neck pain [NP]), VAS–arm pain [AP], NDI, SF-12, and EQ-5D) were administered preoperatively and 3 months postoperatively, allowing 3-month change scores to be calculated. Four established calculation methods were used to calculate anchor-based MCID values using the North American Spine Society (NASS) patient satisfaction scale as the anchor: 1) average change, 2) minimum detectable change (MDC), 3) change difference, and 4) receiver operating characteristic (ROC) curve analysis.

Results

Sixty-one patients (88%) were available at follow-up. At 3 months postoperatively, statistically significant improvement (p < 0.001) was observed for the following PROs assessed: VAS-NP (2.7 ± 3.3), VAS-AP (3.7 ± 3.6), NDI (23.2% ± 19.7%), SF-12 physical component score (PCS; 10.7 ± 9.7), and EQ-5D (0.20 ± 0.23 QALY). Improvement on the SF-12 mental component score (MCS) trended toward significance (3.4 ± 11.4, p = 0.07). The 4 MCID calculation methods generated a range of MCID values for each of the PROs: VAS-NP 2.6–4.0, VAS-AP 2.4–4.2, NDI 16.0%–27.6%, SF-12 PCS 7.0–12.2, SF-12 MCS 0.0–7.2, and EQ-5D 0.05–0.24 QALY. The maximum area under the curve (AUC) was observed for NDI (0.80), and the minimum AUC was observed for SF-12 MCS (0.66) and EQ-5D (0.67). Based on the MDC approach, the MCID threshold was 2.6 points for VAS-NP, 4.1 points for VAS-AP, 17.3% for NDI, 8.1 points for SF-12 PCS, 4.7 points for SF-12 MCS, and 0.24 QALY for EQ-5D. The mean improvement in patient scores at 3 months surpassed the MCID threshold for VAS-NP, NDI, and SF-12 PCS but not for VAS-AP, SF-12 MCS, and EQ-5D.

Conclusions

The ACDF-specific MCID is highly variable depending on the calculation technique used. The MDC approach seems to be most appropriate for MCID calculations in the ACDF population, as it provided a threshold value above the 95% confidence interval of nonresponders (greater than the measurement error) and was closest to the average change of most PROs reported by responders. When the MDC method was applied with the NASS patient satisfaction scale as the anchor, the MCID thresholds were 2.6 points for VAS-NP, 4.1 points for VAS-AP, 17.3% for NDI, 8.1 points for SF-12 PCS, 4.7 points for SF-12 MCS, and 0.24 QALY for EQ-5D.

Revision lumbar surgery in elderly patients with symptomatic pseudarthrosis, adjacent-segment disease, or same-level recurrent stenosis. Part 1. Two-year outcomes and clinical efficacy: clinical article

OBJECT

Same-level recurrent lumbar stenosis, pseudarthrosis, and adjacent-segment disease (ASD) are potential complications that can occur after index lumbar spine surgery, leading to significant discomfort and radicular pain. While numerous studies have demonstrated excellent results following index lumbar spine surgery in elderly patients (age > 65 years), the effectiveness of revision lumbar surgery in this cohort remains unclear. The aim of this study was to assess the long-term effectiveness of revision lumbar decompression and fusion in the treatment of symptomatic pseudarthrosis, ASD, and same-level recurrent stenosis, using validated patient-reported outcomes.

METHODS

After a review of the institutional database, 69 patients who had undergone revision neural decompression and instrumented fusion for ASD (28 patients), pseudarthrosis (17 patients), or same-level recurrent stenosis (24 patients) were included in this study. Baseline and 2-year scores on the visual analog scale for leg pain (VAS-LP), VAS for back pain (VAS-BP), Oswestry Disability Index (ODI), and Zung Self-Rating Depression Scale (SDS) as well as the time to narcotic independence, time to return to baseline activity level, health state utility (EQ-5D, the EuroQol-5D health survey), and physical and mental component summary scores of the 12-Item Short-Form Health Survey (SF-12 PCS and MCS) were assessed.

RESULTS

Compared with the preoperative status, VAS-BP was significantly improved 2 years after surgery for ASD (mean ± standard deviation 9 ± 2 vs 4.01 ± 2.56, p = 0.001), pseudarthrosis (7.41 ± 1 vs 5.52 ± 3.08, p = 0.02), and same-level recurrent stenosis (7 ± 2.00 vs 5.00 ± 2.34, p = 0.003). The 2-year ODI was also significantly improved after surgery for ASD (29 ± 9 vs 23.10 ± 10.18, p = 0.001), pseudarthrosis (28.47 ± 5.85 vs 24.41 ± 7.75, p = 0.001), and same-level recurrent stenosis (30.83 ± 5.28 vs 26.29 ± 4.10, p = 0.003). The Zung SDS score and SF-12 MCS did not change appreciably after surgery in any of the cohorts, with an overall mean 2-year change of 1.01 ± 5.32 (p = 0.46) and 2.02 ± 9.25 (p = 0.22), respectively.

CONCLUSIONS

Data in this study suggest that revision lumbar decompression and extension of fusion for symptomatic pseudarthrosis, ASD, and same-level recurrent stenosis provides improvement in low-back pain, disability, and quality of life and should be considered a viable treatment option for elderly patients with persistent or recurrent back and radicular pain. Mental health symptoms may be more refractory to revision surgery.

Minimum clinically important difference in pain, disability, and quality of life after neural decompression and fusion for same-level recurrent lumbar stenosis: understanding clinical versus statistical significance

OBJECT

Spine surgery outcome studies rely on patient-reported outcome (PRO) measurements to assess treatment effect, but the extent of improvement in the numerical scores of these questionnaires lacks a direct clinical meaning. Because of this, the concept of a minimum clinically important difference (MCID) has been used to measure the critical threshold needed to achieve clinically relevant treatment effectiveness. As utilization of spinal fusion has increased over the past decade, so has the incidence of same-level recurrent stenosis following index lumbar fusion, which commonly requires revision decompression and fusion. The MCID remains uninvestigated for any PROs in the setting of revision lumbar surgery for this pathology.

METHODS

In 53 consecutive patients undergoing revision surgery for same-level recurrent lumbar stenosis-associated back and leg pain, PRO measures of back and leg pain were assessed preoperatively and 2 years postoperatively, using the visual analog scale for back pain (VAS-BP) and leg pain (VAS-LP), Oswestry Disability Index (ODI), Physical and Mental Component Summary categories of the 12-Item Short Form Health Survey (SF-12 PCS and MCS) for quality of life, Zung Depression Scale (ZDS), and EuroQol-5D health survey (EQ-5D). Four established anchor-based MCID calculation methods were used to calculate MCID (average change; minimum detectable change; change difference; and receiver operating characteristic curve analysis) for 2 separate anchors (health transition index of the SF-36 and the satisfaction index).

RESULTS

All patients were available for 2-year PRO assessment. Two years after surgery, a significant improvement was observed for all PROs assessed. The 4 MCID calculation methods generated a range of MCID values for each of the PROs (VAS-BP 2.2-6.0, VAS-LP 3.9-7.5, ODI 8.2-19.9, SF-12 PCS 2.5-12.1, SF-12 MCS 7.0-15.9, ZDS 3.0-18.6, and EQ-5D 0.29-0.52). Each patient answered synchronously for the 2 anchors, suggesting both of these anchors are equally appropriate and valid for this patient population.

CONCLUSIONS

The same-level recurrent stenosis surgery-specific MCID is highly variable based on calculation technique. The "minimum detectable change" approach is the most appropriate method for calculation of MCIDs in this population because it was the only method to reliably provide a threshold above the 95% confidence interval of the unimproved cohort (greater than the measurement error). Based on this method, the MCID thresholds following neural decompression and fusion for symptomatic same-level recurrent stenosis are 2.2 points for VAS-BP, 5.0 points for VAS-LP, 8.2 points for ODI, 2.5 points for SF-12 PCS, 10.1 points for SF-12 MCS, 4.9 points for ZDS, and 0.39 QALYs for EQ-5D.