National Trends in the Surgical Management of Adult Lumbar Isthmic Spondylolisthesis: 1998 to 2011

Comparing Patient-Reported Outcomes, Complications, Readmissions, and Revisions in Posterior Lumbar Fusion With, Versus Without, an Interbody Device

STUDY DESIGN

Retrospective analysis on prospectively collected data.

OBJECTIVES

To compare posterior lumbar fusions with versus without an interbody in: (1) Patient-reported outcomes (PROs) at 1 year and (2) postoperative complications, readmission, and reoperations.

SUMMARY OF BACKGROUND DATA

Elective lumbar fusion is commonly used to treat various lumbar pathologies. Two common approaches for open posterior lumbar fusion include posterolateral fusion (PLF) alone without an interbody and with an interbody through techniques, like transforaminal lumbar interbody fusion. Whether fusion with or without an interbody leads to better outcomes remains an area of active research.

PATIENTS AND METHODS

The Lumbar Module of the Quality Outcomes Database was queried for adults undergoing elective primary posterior lumbar fusion with or without an interbody. Covariates included demographic variables, comorbidities, primary spine diagnosis, operative variables, and baseline PROs, including Oswestry Disability Index, North American Spine Society satisfaction index, numeric rating scale-back/leg pain, and Euroqol 5-dimension. Outcomes included complications, reoperations, readmissions, return to work/activities, and PROs. Propensity score matching and linear regression modeling were used to estimate the average treatment effect on the treated to assess the impact of interbody use on patient outcomes.

RESULTS

After propensity matching, there were 1044 patients with interbody and 215 patients undergoing PLF. The average treatment effect on the treated analysis showed that having an interbody or not had no significant impact on any outcome of interest, including 30-day complications and reoperations, 3-month readmissions, 12-month return to work, and 12-month PROs.

CONCLUSION

There were no discernible differences in outcomes between patients undergoing PLF alone versus with an interbody in elective posterior lumbar fusion. These results add to the growing body of evidence that posterior lumbar fusions with and without an interbody seem to have similar outcomes up to 1 year postoperatively when treating degenerative lumbar spine conditions.

Trends of Different Surgical Approaches in Patients With Single-Level Lumbar Isthmic Spondylolisthesis: A National Registry Analysis

BACKGROUND

A variety of surgical approaches (anterior vs. posterior vs. anterior and posterior) are available for Isthmic Spondylolisthesis (IS). The aim of our study was to analyze the pattern and 30-day outcomes in patients undergoing different surgical approaches for single-level IS.

MATERIALS AND METHODS

National Surgical Quality Improvement Program (NSQIP) database was queried using the ICD-9/10 and CPT 4^th edition, from 2012 to 2020. We included patients 18-65 years of age who underwent spine fusions for IS. Outcomes were a length of stay (LOS), discharge disposition, 30-day complications, hospital readmission, and complication rates.

RESULTS

Of 1036 patients who underwent spine fusions for IS, 838 patients (80.8%) underwent posterior only, 115 patients (11.1%) underwent anterior-only fusions and the rest (8%) underwent combined anterior and posterior procedures. 60% of patients in the posterior-only cohort had at least one comorbidity compared to 54% of patients in anterior only and 55% of patients in the combined cohort. No statistically significant differences in terms of LOS (3 days each) and discharge to home (96% vs. 93% vs. 94%) were noted among the anterior-only, posterior-only and combined cohorts, p> 0.05. In terms of 30-day complication rates, combined procedures had slightly higher rates (13%) compared to anterior (10%) or posterior-only (9%) procedures.

CONCLUSION

Posterior-only fusions were performed in 80% of patients with IS. No differences in terms of LOS, discharge disposition to home, 30-day complications, hospital readmission and reoperation rates were noted across the cohorts.

In Single-Level, Open, Posterior Lumbar Fusion, Does Transforaminal Lumbar Interbody Fusion or Posterolateral Fusion Lead to Better Outcomes?

BACKGROUND

Two common approaches for open, one-level, posterior lumbar fusions include transforaminal lumbar interbody fusion (TLIF) and posterolateral fusion (PLF) alone without an interbody.

OBJECTIVE

To compare TLIF vs PLF alone in (1) discharge disposition, (2) return to work (RTW), and (3) patient-reported outcomes (PROs).

METHODS

A single-center, retrospective cohort study was undertaken between October 2010 and May 2021, all with a 1-year follow-up and excluding patients with isthmic spondylolisthesis. Minimum clinically important difference for each PRO was used, which included Numeric Rating Scale (NRS) and Oswestry Disability Index (ODI). Logistic/linear regression controlled for age, body mass index, disc height, flexion-extension movement, amount of movement on flexion-extension, and spondylolisthesis grade.

RESULTS

Of 850 patients undergoing open, 1-level, posterior lumbar fusion, 591 (69.5%) underwent a TLIF and 259 (30.5%) underwent a PLF alone. Patients undergoing TLIF were younger (59.0 ± 11.3 vs 63.3 ± 12.6, P < .001), had higher body mass index (31.3 ± 6.6 vs 30.2 ± 12.6, P = .019), and more often had private insurance (50.3% vs 39.0%, P < .001). Regarding discharge disposition, no significance was found in multivariate regression (odds ratio = 2.07, 95% CI = 0.39-10.82, P = .385) with similar RTW between TLIF and PLF alone (80.8% vs 80.4%, P = .645) (odds ratio = 1.15, 95% CI = 0.19-6.81, P = .873). Regarding PROs, patients undergoing a TLIF had higher preoperative (6.7 ± 2.3 vs 6.4 ± 2.5, P = .046) and 3-month NRS-back pain (3.4 ± 2.6 vs 2.9 ± 2.5, P = .036), with similar 12-month NRS-back pain. Regarding NRS-leg pain, no differences were observed preoperatively ( P = .532) and at 3 months ( P = .808). No other significant differences were observed in ODI.

CONCLUSION

TLIF patients had slightly higher NRS-back pain at baseline and 3 months, but similar NRS-leg pain, despite the added risk of placing an interbody. No differences were seen in discharge disposition, RTW, and 12-month pain scores and ODI.

Trends in Single-Level Lumbar Fusions Over the Past Decade Using a National Database

OBJECTIVE

To compare rates of different fusion techniques using a nationwide database over the last decade and identify differences in complications and readmissions based on fusion technique.

METHODS

All elective, single-level lumbar fusions performed by orthopaedic surgeons from 2011 to 2020 were identified from the American College of Surgeons National Surgical Quality Improvement Program. Rates of lumbar fusion technique posterolateral decompression and fusion [PLDF], combined transforaminal lumbar interbody fusion and PLDF, anterior lumbar or lateral lumbar interbody fusion [ALIF/LLIF], and combined ALIF/LLIF and PLDF were recorded, and 30-day complications and readmissions were compared. Secondary analysis included multiple logistic regression to determine independent predictors of each outcome.

RESULTS

Inclusion criteria were met by 28,413 fusions: 8749 (30.8%) PLDFs, 11,973 (42.1%) transforaminal lumbar interbody fusions, 4769 (16.8%) ALIF/LLIFs, and 2922 (10.3%) combined ALIF/LLIF and PLDFs. The number of fusions increased over time with 1227 fusions performed in 2011 and 3958 fusions performed in 2019. Interbody fusions also increased over time with a subsequent decrease in PLDFs (39.0% in 2011, 25.2% in 2020). Patients were more likely to be discharged home over the course of the decade (85.4% in 2011, 95.0% in 2020). No difference was observed between the techniques regarding complications or readmissions. The modified 5-item frailty index was predictive of complications (odds ratio, 2.05; P = 0.001) and readmissions (odds ratio, 2.61; P < 0.001).

CONCLUSIONS

Lumbar fusions have continued to increase over the last decade with an increasing proportion of interbody fusions. Complications and readmissions appear to be driven by patient comorbidity and not fusion technique.

The utility of the CADISS® system in the dissection of epidural fibrosis in revision lumbar spine surgery (A case series)

Spine surgery and spinal fusion surgery are rising. Revision rates following initial surgery are between 8 and 45%. Epidural fibrosis is a common response to spine surgery for most patients and increases complications in revision surgery. Previous research suggests using MESNA (Sodium 2-mercaptoethane sulfonate) in combination with mechanical blunt dissection safely reduces surgical complications. MESNA is a mucolytic agent which selectively cleaves disulphide bonds involved in the adherence and strength of fibrosis, meaning cutting instruments are not needed. The Chemically Assisted DISSection (CADISS®) System is an optimised non-cutting surgical device, consisting of a reconstitution cartridge for MESNA preparation, irrigated surgical instruments, and a footswitch to control MESNA release. This is the first study to investigate the use of the CADISS® System in revision spine surgery.

Methods

This was a prospective, open label, observational case study. We enrolled 21 patients for revision spine surgery with the CADISS® System at two Belgium sites. The primary assessment was the number of successful removals of epidural fibrosis without cutting. The amount of MESNA used, total dissection and procedure time were recorded. For secondary criterion, the surgeons assessed global satisfaction, facilitation of dissection, quickness of action, usability, bleeding reduction and visualisation of the cleavage plane using an 11-point Likert scale (0–10). Due to the exploratory nature, no formal statistical analysis was planned. We calculated the percentage and confidence interval of successful procedures, the medians and corresponding interquartile range of the Likert criterion, and the mean (±SD) of the amount of MESNA used, CADISS® dissection time and total procedure time.

Results

24 fibrosis dissections were performed in 19 patients and 23 were successful (95.8%, CI: 78.9%; 99.9%). The mean amount of MESNA used, mean dissection time and procedure time were 16 ml (±4.94), 16.5 min (±16.1) and 86.3 min (±25.1), respectively. No dural tears were reported. The mean global satisfaction score was 9.0 (8.0–9.0). All other Likert criterion had scores of 8.0 or 9.0, excluding quickness of action, which scored 7.0 (6.0–9.0).

Conclusions

The CADISS® System in revision spine surgery has potential to effectively reduce dissection complications.

•

Revision rates following initial surgery are between 8 and 45%. Epidural fibrosis is a common response to spine surgery for most patients and increases complications in revision surgery.

•

Previous research suggests using MESNA (Sodium 2-mercaptoethane sulfonate) in combination with mechanical blunt dissection safely reduces surgical complications. MESNA is a mucolytic agent which selectively cleaves disulphide bonds involved in the adherence and strength of fibrosis, meaning cutting instruments are not needed. The Chemically Assisted DISSection (CADISS®) System is an optimised non-cutting surgical device, consisting of a reconstitution cartridge for MESNA preparation, irrigated surgical instruments, and a footswitch to control MESNA release.

•

We enrolled 21 patients for revision spine surgery with the CADISS® System at two Belgium sites. The primary assessment was the number of successful removals of epidural fibrosis without cutting. The CADISS® System in revision spine surgery has potential to effectively reduce dissection complications.

Beyond the pedicle screw-a patent review

PURPOSE

This review provides an overview of the patent literature on posteriorly placed intrapedicular bone anchors. Conventional pedicle screws are the gold standard to create a fixation in the vertebra for spinal fusion surgery but may lack fixation strength, especially in osteoporotic bone. The ageing population demands new bone anchors that have an increased fixation strength, that can be placed safely, and, if necessary, can be removed without damaging the surrounding tissue.

METHODS

The patent search was conducted using a classification search in the Espacenet patent database. Only patents with a Cooperative Patent Classification of A61B17/70 or A61B17/7001 concerning spinal positioners and stabilizers were eligible for inclusion. The search query resulted in the identification of 731 patents. Based on preset inclusion criteria, a total of 56 unique patents on different anchoring methods were included, reviewed and categorized in this study.

RESULTS

Five unique fixation methods were identified; (1) anchors that use threading, (2) anchors that utilize a curved path through the vertebra, (3) anchors that (partly) expand, (4) anchors that use cement and (5) anchors that are designed to initiate bone ingrowth. Of the anchor designs included in this study, eight had a corresponding commercial product, six of which were evaluated in clinical trials.

CONCLUSION

This review provides insights into worldwide patented intrapedicular bone anchors that aim to increase the fixation strength compared to the conventional pedicle screw. The identified anchoring methods and their working principles can be used for clinical decision-making and as a source of inspiration when designing novel bone anchors.

Isthmic spondylolisthesis in adults… A review of the current literature

Isthmic spondylolisthesis can be defined as the anterior translation of a vertebral body relative to the one subjacent to it and secondary to an abnormality of the pars interarticularis. Isthmic spondylolisthesis is usually asymptomatic and discovered as an incidental radiographic finding. However, it can be symptomatic due to its biomechanical effects on the adjacent neural structures and patients may present with low back and/or radicular leg pain. Standing plain radiographs can be obtained to confirm the presence or assess the degree of isthmic spondylolisthesis. Computed tomography (CT) clearly shows the pars defect and provides a better assessment of the pathology. Magnetic resonance imaging (MRI) is indicated in patients with neurologic manifestations and can be used to assess the degree of foraminal or central stenosis. Conservative management including oral anti-inflammatory medication, physical therapy, and/or transforaminal epidural corticosteroid injections can be utilized initially. Surgery can be considered in the setting of persistent symptoms unrelieved with conservative management or significant neurologic compromise. Several surgical methods and techniques are available in the management of isthmic spondylolisthesis. There has been a significant national increase in the use of interbody fusion posteriorly for the management of isthmic spondylolisthesis. Reports have suggested that interbody fusion can be a cost-effective technique in selected patients with isthmic spondylolisthesis. Future studies are encouraged to further characterize the specific indications of various surgical modalities in patients with isthmic spondylolisthesis.

Transverse Pedicle Angle Is Associated With Pelvic Incidence and Increased in Lumbar Isthmic Spondylolisthesis

STUDY DESIGN

Retrospective radiographic review.

OBJECTIVES

Investigate and quantify transverse pedicle angle (TPA), the medial-to-lateral pedicle angulation, and its potential association with pelvic incidence (PI) in patients with isthmic lumbar spondylolisthesis (ISLS) and compare to those with degenerative lumbar spondylolisthesis (DSLS) and controls.

METHODS

A total of 200 patients (64 ISLS, 70 DSLS, 66 control) were included. TPA was calculated at the L3-5 vertebral levels using axial computed tomography slices. PI was measured on lateral radiographs. Two independent observers completed the measurements. As a sensitivity analysis, TPA was also measured at the most cranial and caudal aspects of the L3-5 vertebral levels of a subset of participants (29 ISLS, 31 DSLS, 35 control) and the cranial to caudal change (ΔTPA) was calculated.

RESULTS

TPA values (mean ± SD) at L4 and L5 for ISLS (L4: 17.3° ± 3.7°, L5: 26.0° ± 5.2°) were significantly higher than those for the DSLS (L4: 14.3° ± 3.8°, L5: 22.2° ± 5.0°) and control (L4: 14.5° ± 3.9°, L5: 20.7° ± 3.8°) groups. TPA in the DSLS group was significantly higher than controls at L5, but not L4. High PI predicted wider TPA at L5 in both DSLS and ISLS. ΔTPA (mean ± SD) increased sequentially proceeding through the L3-5 spinal levels for the ISLS (L3: 6.8° ± 4.4°, L4: 8.7° ± 5.2°, L5: 15.6° ± 9.0°), DSLS (L3: 8.2° ± 6.0°, L4: 8.3° ± 5.9°, L5: 18.3° ± 7.2°), and control (L3: 6.8° ± 4.4°, L4: 8.2° ± 4.7°, L5: 17.7° ± 7.0°) groups.

CONCLUSIONS

TPA was significantly increased in ISLS compared with DSLS and controls. High PI significantly predicted high TPA at the L5 vertebral level in ISLS and DSLS. ΔTPA increased sequentially proceeding through the lumbar spine across groups.

Lumbar surgical drains do not increase the risk of infections in patients undergoing spine surgery

PURPOSE

The aim of this study was to characterize if the use of surgical drains or length of drain placement following spine surgery increases the risk of post-operative infection.

METHODS

Records of patients undergoing elective spinal surgery at a tertiary care center were collected between May 5, 2016 and August 16, 2018. Pre-operative baseline characteristics were recorded including patient's demographics and comorbidities. Intraoperative procedure information was documented related to procedure type, blood loss, and antibiotics used. Following surgery, patients were then further subdivided into two groups: patients who were discharged with a spinal surgical site drain and patients who did not receive a drain. Post-operative surgical variables included length of stay (LOS), drain length, number of antibiotics given, and type of post-operative infection. Univariate and multivariate statistical analysis was conducted.

RESULTS

A total of 671 patients were included in the current study, 386 (57.5%) with and 285 (42.5%) without the drain. The overall infection rate was 5.7% with 6.22% among patients with the drain compared to 4.91% in patients without drain. The univariate analysis identified the following variables to be significantly associated with the infection: total number of surgical levels, spinal region, blood loss, redosing of antibiotics, length of stay, length of drain placement, and number of antibiotics (P < 0.05). However, the multivariate analysis none of the predictors was significant.

CONCLUSIONS

The current study shows that the placement of drain does not increase rate of infection, irrespective of levels, length of surgery, or approach.

Relationship between the elastic modulus of the cage material and the biomechanical properties of transforaminal lumbar interbody fusion: A logarithmic regression analysis based on parametric finite element simulations

BACKGROUND AND OBJECTIVE

Conventional method for evaluating the biomechanical effects of a specific elastic modulus of cage (cage-E) on spinal fusions requires establishing a "one-on-one" biomechanical model, which seems laborious and inefficient when dealing with the emergence of numerous cage materials with various cage-Es. We aim to offer a much convenient method to instantly predicting the biomechanical effects of any targeted cage-E on transforaminal lumbar interbody fusion (TLIF) by using a parametric finite element (FE) analysis to determining the regression relationship between cage-E and biomechanical properties of TLIF.

MATERIALS AND METHODS

A L4/5 FE TLIF construct was modeled. Cage-E was linearly increased from 0.1 GPa (cancellous bone) to 110 GPa (titanium alloy). The function equations for assessing the influence of cage-E on the biomechanical indexes of TLIF were established using a logarithmic regression analysis.

EXPERIMENTAL RESULTS

As cage-E increased from 0.1 GPa to 110 GPa, all the biomechanical indexes initially increased or decayed rapidly, and then slowed over time. Logarithmic regression models and functional equations were successfully established between cage-E and these indexes (P<0.0001). Their determination coefficients ranged from 0.72 to 0.99. The range of motions decreased from 0.37-1.10° to 0.20-1.07°. The mean stresses of the central and peripheral grafts reduced from 0.10-0.41 and 0.25-0.42 MPa to 0.03-0.04 and 0.19-0.27 MPa, respectively. In addition, the maximum stresses of the screw-bone interface and posterior instrumentation reduced from 11.76-25.04 and 8.91-84.68 MPa to 9.71-18.92 and 6.99-70.59 MPa, respectively. Finally, the maximum stresses of the cage and endplate increased from 0.28-1.35 MPa and 3.90-8.63 MPa to 14.86-36.16 MPa and 11.01-36.55 MPa, respectively.

CONCLUSIONS

The decrease of cage-E reduces the risks of cage subsidence, cage breakage, and pseudarthrosis, while increasing the risk of instrumentation failure. The logarithmic regression models optimally demonstrate the relationship between cage-E and biomechanical properties of TLIF. The functional equations based on these models can be adopted to predict the biomechanical effects of any targeted cage-Es on TLIF, which effectively simplifies the procedures for the biomechanical assessments of cage materials.

Direct reduction of high-grade lumbosacral spondylolisthesis with anterior cantilever technique - surgical technique note and preliminary results

Backgrounds

Surgical reduction for high-grade spondylolisthesis is beneficial for restoring sagittal balance and improving the biomechanical environment for arthrodesis. Compared to posterior total laminectomy and long instrumentation, anterior lumbar inter-body fusion (ALIF) is less invasive and has the biomechanical advantage of restoring the original disk height and increasing lumbar lordosis, thus improving sagittal balance. However, the application of ALIF is still limited in treating low-grade spondylolisthesis. In this study, we developed a new technique termed anterior cantilever procedure to directly reduce the slippage of high-grade lumbosacral spondylolisthesis. The purpose of our study was to investigate the surgical outcomes of the anterior cantilever procedure followed by ALIF and posterior mono-segment instrumented fixation in high-grade spondylolisthesis.

Methods

All patients with high-grade spondylolisthesis who underwent anterior cantilever procedure followed by anterior lumbar inter-body fusion (ALIF) and posterior mono-segment instrumented fixation between November 2006 and July 2017 were enrolled in our study. The slip percentage, Dubousset’s lumbosacral angle, pelvic tilt, sacral slope, pelvic incidence, and sagittal alignment were measured pre-operatively and postoperatively at the last follow-up. Surgery time, blood loss, complications, and hospital stay were also collected and analysed.

Results

A total of 11 consecutive patients with high-grade spondylolisthesis patients were included and analysed. All of the high-grade spondylolisthesis in our series occurred at the L5-S1 level. The median age was 37 years, and the median follow-up duration was 36 months. The average slip reduction was 30% (60 to 30%, P < 0.01), and the average correction of Dubousset’s lumbosacral angle was 13.8° (84.1° to 97.9°, P < 0.01). The median intra-operative blood loss was 300 mL. All patients attained improved sagittal balance after the operation and achieved solid fusion within 9 months after surgery. No incidences of implant failure, permanent neurological deficit, or pseudarthrosis were recorded at the last follow-up.

Conclusions

Anterior cantilever procedure followed by ALIF and posterior mono-segment instrumented fixation is a valid procedure for treating high-grade spondylolisthesis. It achieved a high fusion rate, partially reduced slippage, and significantly improved lumbosacral angle, while minimizing common complications, such as pseudarthrosis, nerve traction injury, excessive soft tissue dissection, and blood loss in posterior reduction procedures. However, posterior instrumentation is still required to the structural stability in the ALIF procedure.

Level of evidence

IV

National utilization and inpatient safety measures of lumbar spinal fusion methods by race/ethnicity

BACKGROUND CONTEXT

Degenerative lumbar conditions are prevalent, disabling, and frequently managed with decompression and fusion. Black patients have lower spinal fusion rates than White patients.

PURPOSE

Determine whether specific lumbar fusion procedure utilization differs by race/ethnicity and whether length of stay (LOS) or inpatient complications differ by race/ethnicity after accounting for procedure performed.

STUDY DESIGN

Large database retrospective cohort study PATIENT SAMPLE: Lumbar fusion recipients at least age 50 in the 2016 National Inpatient Sample with diagnoses of degenerative lumbar conditions.

OUTCOME MEASURES

Type of fusion procedure used and inpatient safety measures including LOS, prolonged LOS, inpatient medical and surgical complications, mortality, and cost.

METHODS

We examined the association between race/ethnicity and the safety measures above. Covariates included several patient and hospital factors. We used multiple linear or logistic regression to determine the association between race and fusion type (PLF, P/TLIF, ALIF, PLF + P/TLIF, and PLF + ALIF [anterior-posterior fusion]) and to determine whether race was associated independently with inpatient safety measures, after adjustment for patient and hospital factors.

RESULTS

Fusion method use did not differ among racial/ethnic groups, except for somewhat lower anterior-posterior fusion utilization in Black patients compared to White patients (crude odds ratio [OR]: 0.81 [0.67-0.97]). Inpatient safety measures differed by race/ethnicity for rates of prolonged LOS (Blacks 18.1%, Hispanics 14.5%, and Whites 11.7%), medical complications (Blacks 9.9%, Hispanics 8.7%, and Whites 7.7%), and surgical complications (Blacks 5.2%, Hispanics 6.9%, and Whites 5.4%). Differences persisted after adjustment for procedure type as well as patient and hospital factors. Blacks and Hispanics had higher risk for prolonged LOS compared to Whites (adjusted OR Blacks 1.39 [95% confidence interval {CI} 1.22-1.59]; Hispanics 1.24 [95% CI 1.02-1.52]). Blacks had higher risk for inpatient medical complications compared to Whites (adjusted OR 1.24 [95% CI 1.05-1.48]), and Hispanics had higher risk for inpatient surgical complications compared to Whites (adjusted OR 1.34 [95% CI 1.06-1.68]).

CONCLUSIONS

Fusion method use was generally similar between racial/ethnic groups. Inpatient safety measures, adjusted for procedure type, patient and hospital factors, were worse for Blacks and Hispanics.

Comparison of Clinical Outcomes Between Posterior Instrumented Fusion With and Without Interbody Fusion for Isthmic Spondylolisthesis

STUDY DESIGN

A multicenter ambispective study using the Canadian Spine Outcomes and Research Network to compare clinical outcomes in adult patients with isthmic spondylolisthesis who received surgery.

OBJECTIVE

The purpose of this study is to compare 1-year postoperative clinical outcomes between posterior instrumented fusion with and without interbody fusion in patients with isthmic spondylolisthesis.

SUMMARY OF BACKGROUND DATA

Despite the increased use of interbody fusion in patients with isthmic spondylolisthesis, clinical superiority has not been demonstrated. It remains unclear what the optimal surgical approach is for this population.

MATERIALS AND METHODS

The primary outcome was changed in leg pain at 1 year. Secondary outcomes were changed in Oswestry Disability Index, Short Form-12 Physical Component Score, and back pain at 1-year postoperative follow-up, estimated intraoperative blood loss, length of surgery, length of stay, number of transfusions, and adverse events. Descriptive statistics, Student t test, χ2 test, and stepwise multivariable regression were used for analysis.

RESULTS

In total, 300 patients were included in this study. Of the 300 patients, 252 received posterolateral instrumented fusion with interbody fusion and 48 received posterolateral instrumented fusion alone. There were no significant differences in primary and secondary clinical outcomes at 1-year postoperative follow-up between the 2 groups. There were no significant differences in estimated blood loss (441 vs. 356 mL), length of surgery (210 vs. 224 min), length of stay (4 vs. 4 d), rate of transfusions (5.6% vs. 8.3%), and number of adverse events (33% vs. 23%) between patients who received interbody fusion and patients who did not. The addition of interbody fusion was not a significant variable for primary and secondary clinical outcomes in the stepwise multivariable regression analysis.

CONCLUSIONS

There were no significant differences in clinical outcomes at 1 year or in the number of early complications between patients who received posterolateral fusion or posterior/transformational lumbar interbody fusion.

LEVEL OF EVIDENCE

Level III.

Trends in lumbar spinal fusion-a literature review

Over the past several decades, there has been an upward trend in the total number of spinal fusion procedures worldwide. Advanced spinal fusion techniques with or without internal fixation, additional innovations in surgical approaches, innovative implants including a wide variety of interbody devices, and new alternatives in bone grafting materials are some reasons for the increasing number of spine fusion procedures. Moreover, the indications for spinal fusion have broadened over time. Initially developed for the treatment of instability and deformity due to tuberculosis, scoliosis, and traumatic injury, spinal fusion surgery has now a wide range of indications like spondylolisthesis, congenital or degenerative deformity, spinal tumors, and pseudarthrosis, with degenerative disorders as the most common indication. This review emphasizes current lumbar fusion techniques and their development in the past decades.

Selective cement augmentation of cranial and caudal pedicle screws provides comparable stability to augmentation on all segments in the osteoporotic spine: a finite element analysis

Background

Cement-augmented pedicle screw instrumentation (CAPSI) has been proven to significantly increase the biomechanical stability in the osteoporotic lumbar spine. However, besides the merits, it is responsible for the inevitable cement leakage growing with more instrumented segments and volumes involved. This study aimed to compare the biomechanical performance of pedicle screws augmented on all segments with those augmented only on the cranial and caudal vertebrae selectively.

Methods

The finite element model of L3-S1 was modeled with the CT data of a healthy volunteer, the solid/fenestrated pedicle screws from micro-CT scans of physical screws, and bone cement from the CT scans of a postoperative patient with CAPSI. Three different augmented strategies for pedicle screws were taken into consideration: augmentation at each pedicle trajectory (Model A), selective augmentation at the cranial and caudal pedicle trajectories (Model B), and pedicle trajectories without augmentation (Model C). A total of six surgical models were constructed: Models A, B, and C were subdivided into double segmental fusion from L4 to S1 (Models A1, B1, and C1) and multi-segment fusion from L3 to S1 (Models A2, B2, and C2). The Range of motion (ROM), stress on the cage, and stress on the fixed segments were compared among the six models.

Results

The ROM at the fusion segments decreased in all instrumentation models. The ROMs of Model B and Model A are similar in each direction, while that of Model C is significantly larger. The differences in the ROMs between Model A and Model B were noted to be less than 0.1°. Compared with Models A1 and A2, the peak Von Mise stress on the cage-endplate interface and pedicle screws were slightly higher in Models B1 and B2. In contrast, the stress of Models C1 and C2 increased significantly. The compressive stress was concentrated in the screw head, the cranial and caudal screws, and rods.

Conclusions

The selective augmentation of pedicle screws is capable of providing reliable stability in short-segment posterior fixation (2- or 3-level). It could be a potential optimal procedure to minimize the associated complications of CAPSI.

The necessity and risk factors of subsequent fusion after decompression alone for lumbar spinal stenosis with lumbar spondylolisthesis: 5 years follow-up in two different large populations

BACKGROUND/CONTEXT

Although decompression without fusion is a reasonable surgical treatment option for some patients with lumbar spinal stenosis (LSS) secondary to spondylolisthesis, some of these patients will require secondary surgery for subsequent fusion. Long-term outcome and need for subsequent fusion in patients treated with decompression alone in the setting of lumbar spondylolisthesis remains controversial.

PURPOSE

The aim of this study was to examine the rate, timing, and risk factors of subsequent fusion for patients after decompression alone for LSS with spondylolisthesis.

STUDY DESIGN/SETTING

A retrospective cohort study.

PATIENT SAMPLE

Patients who had LSS with spondylolisthesis and underwent decompression alone at 1 or 2 levels as a primary lumbar surgery with more than 5 year follow-up.

OUTCOME MEASURES

The rate, timing, and risk factors for subsequent fusion.

METHODS

Subjects were extracted from both public and private insurance resources in a nationwide insurer database. Risk factors for subsequent fusion were evaluated by multivariate cox proportion-hazard regression controlling for age, gender, comorbidities and the presence or absence of claudication.

RESULTS

Five thousand eight hundred and seventy-five patients in the public insurance population (PI population) and 1,456 patients in the private insurance population (PrI population) were included in this study. The rates of patients who needed subsequent fusion were 1.9% at 1 year, 3.5% at 2 years, and 6.7% at 5 years in the PI population, whereas they were 4.3% at 1 year, 8.9% at 2 years, 14.6% at 5 years in the PrI population. The time to subsequent fusion was 730 (365-1234) days in the PI population and 588 (300-998) days in the PrI population. Age less than 70 years, presence of neurogenic claudication and rheumatoid arthritis (RA)/collagen vascular diseases (CVD) were independent risk factors for subsequent fusion in both populations.

CONCLUSIONS

Decompression surgery alone can demonstrate good outcomes in some patients with LSS with spondylolisthesis. It is important for surgeons to recognize, however, that patient age less than 70 years, symptomatic neurogenic claudication, and presence of RA and/or CVD are significant independent factors associated with greater likelihood of needing secondary fusion surgery.

Complications and Mortality Rates Following Surgical Management of Extradural Spine Tumors in New York State

STUDY DESIGN

Database analysis.

OBJECTIVE

To evaluate complications and mortality in patients undergoing surgical management of extradural spinal tumors in New York State.

SUMMARY OF BACKGROUND DATA

Metastatic spine surgery has a high rate of complications but most studies are limited to single institutions.

METHODS

The Statewide Planning and Research Cooperative System was used to identify patients with extradural spinal tumors undergoing surgery in New York State from 2006 to 2015. Bivariate and multivariate logistic regression analyses were used to estimate outcomes.

RESULTS

Four thousand seven hundred sixty-seven patients were identified, the majority of patients were male and white a median age of 61. The complication rate was 17.6% and the mortality rate within 30 days of discharge was 12.2%. Multivariate analysis showed the odds of complications were higher in males compared with females (odds ratio [OR]: 1.27; 95% confidence interval [CI]: 1.05-1.52, P = 0.01), and patients on Medicaid compared with patients on private insurance (OR: 1.42; 95% CI: 1.03-1.96, P = 0.03). Analysis of hospital characteristics showed lower volume hospitals (OR 1.48; 95% CI: 1.03-2.13, P value = 0.03), and teaching hospitals (OR: 1.47; 95% CI: 1.03-2.09, P = 0.04), have higher odds of complications compared with high-volume hospitals and nonteaching hospitals. Multivariate analysis showed higher odds of mortality within 30 days of discharge in patients of older age (OR: 1.02; 95% CI: 1.01-1.03, P value = 0.001), low-volume hospitals compared with high-volume hospitals (OR: 1.36; 95% CI: 1.09-1.79, P value = 0.02), hospitals with low bed size compared with high bed size (OR: 1.43; 95% CI: 1.12-1.83, P value = 0.01), and urban hospitals compared with rural hospitals (OR: 3.04; 95% CI: 2.03-4.56, P value = 0.001).

CONCLUSION

Low-volume hospitals are associated with complications and mortality in patients with metastatic spine disease.

LEVEL OF EVIDENCE

3.

Investigation and Feasibility of Combined 3D Printed Thermoplastic Filament and Polymeric Foam to Simulate the Cortiocancellous Interface of Human Vertebrae

Disorders of the spine are among the most common indications for neurosurgical and orthopedic surgical interventions. Spinal fixation in the form of pedicle screw placement is a common form of instrumentation method in the lower cervical, thoracic, and lumbar spine. A vital principle to understand for the safe and accurate placement of pedicle screws is the palpable difference between the cortical and cancellous bone, both of which have different material properties and compositions. Probing and palpation of the hard cortical bone, also known as the “ventral lamina”, covering the neural elements of the spinal canal during screw placement provides manual feedback to the surgeon, indicating an impending breach if continued directional force is applied. Generally, this practice is learned at the expense of patients in live operating room scenarios. Currently, there is a paucity of human vertebra simulation designs that have been validated based on the in vivo ultrastructure and physical properties of human cortical and cancellous bone. In this study, we examined the feasibility of combining three-dimensionally printed thermoplastic polymers with polymeric foam to replicate both the vertebral corticocancellous interface and surface anatomy for procedural education.

Quality and Safety Improvement in Spine Surgery

STUDY DESIGN

Review article.

OBJECTIVES

A narrative review of the literature on the current advances and limitations in quality and safety improvement initiatives in spine surgery.

METHODS

A comprehensive literature search was performed using Ovid MEDLINE focusing on 3 preidentified concepts: (1) quality and safety improvement, (2) reporting of outcomes and adverse events, and (3) prediction model and practice guidelines. The search was conducted under appropriate subject headings and using relevant text words. Articles were screened, and manuscripts relevant to this discussion were included in the narrative review.

RESULTS

Quality and safety improvement remains a major research focus attracting investigators from the global spine community. Multiple databases and registries have been developed for the purpose of generating data and monitoring the progress of quality and safety improvement initiatives. The development of various prediction models and clinical practice guidelines has helped shape the care of spine patients in the modern era. With the reported success of exemplary programs initiated by the Northwestern and Seattle Spine Team, other quality and safety improvement initiatives are anticipated to follow. However, despite these advancements, the reporting metrics for outcomes and adverse events remain heterogeneous in the literature.

CONCLUSION

Constant surveillance and continuous improvement of the quality and safety of spine treatments is imperative in modern health care. Although great advancement has been made, issues with reporting outcomes and adverse events persist, and improvement in this regard is certainly needed.

Long-term outcome of fusion for degenerative disc disease in the lumbar spine

Aims

Chronic low back pain due to degenerative disc disease is sometimes treated with fusion. We compared the outcome of three different fusion techniques in the Swedish Spine Register: noninstrumented posterolateral fusion (PLF), instrumented posterolateral fusion (IPLF), and interbody fusion (IBF).

Patients and Methods

A total of 2874 patients who were operated on at one or two lumbar levels were followed for a mean of 9.2 years (3.6 to 19.1) for any additional lumbar spine surgery. Patient-reported outcome data were available preoperatively (n = 2874) and at one year (n = 2274), two years (n = 1958), and a mean of 6.9 years (n = 1518) postoperatively and consisted of global assessment and visual analogue scales of leg and back pain, Oswestry Disability Index, EuroQol five-dimensional index, 36-Item Short-Form Health Survey, and satisfaction with treatment. Statistical analyses were performed with competing-risks proportional hazards regression or analysis of covariance, adjusted for baseline variables.

Results

The number of patients with additional surgery were 32/183 (17%) in the PLF group, 229/1256 (18%) in the IPLF group, and 439/1435 (31%) in the IBF group. With the PLF group as a reference, the hazard ratio for additional lumbar surgery was 1.16 (95% confidence interval (CI) 0.78 to 1.72) for the IPLF group and 2.13 (95% CI 1.45 to 3.12) for the IBF group. All patient-reported outcomes improved after surgery (p < 0.001) but were without statistically significant differences between the groups at the one-, two- and 6.9-year follow-ups (all p ≥ 0.12).

Conclusion

The addition of interbody fusion to posterolateral fusion was associated with a higher risk for additional surgery and showed no advantages in patient-reported outcome Cite this article: Bone Joint J 2019;101-B:1526–1533

A ball-slide-type interbody distractor is effective in posterior reduction and internal fixation for patients with mid- to high-grade isthmic spondylolisthesis enrolled in a randomized clinical trial

STUDY DESIGN

Clinical and radiographic results of a randomized, controlled, double-blind clinical trial OBJECTIVE:: To investigate the clinical applicability of a ball-point slide-type interbody distractor in posterior reduction and internal fixation for mid- to high-grade isthmic spondylolisthesis.

SUMMARY OF BACKGROUND DATA

Posterior reduction and internal fixation is the effective treatment for spondylolisthesis. However, for the mid and high-grade isthmic spondylolisthesis patients with the conditions of vertebral osteoporosis and extremely narrow intervertebral space, the reduction is difficult; post-surgery intervertebral space height lost becomes serious; the fracture and loosening rate of fixation system is higher. No study regarding the prevention of these adverse outcomes in this technique is reported.

METHODS

A total of 59 patients of mid and high-grade isthmic spondylolisthesis were randomly divided into random groups (investigational group and control group) applying simple randomized method in this study. In addition, 30 patients received posterior reduction and internal fixation as control. Twenty-nine patients received posterior reduction and internal fixation by ball-point slide-type interbody distractor were assigned to the investigational group. X-ray examination was performed before and after operation. The degree of reduction, height of intervertebral space were compared. The preoperative and postoperative Visual Analog Scale (VAS) and Oswestry Disability Index (ODI) were evaluated. Additionally, rate of the fixation system fracture was also assessed.

RESULTS

Before treatment, there were no significant differences in ISH (P = .72), DR (P = .85), VAS of back pain (P = .55), VAS of leg pain (P = .83) and ODI (P = .68) were found between 2 groups. After 12-month treatment, there were no significant differences in ISH (P = .26), VAS of back pain (P = .09) and VAS of leg pain (P = .96) between two groups. Significant differences of DR (P = .02), ODI (P = .03) and adverse events (P = .00) were found between 2 groups.

CONCLUSIONS

The results of this prospectively study showed that the ball-point slide-type interbody distractor in the posterior reduction and internal fixation produced good outcomes after 12-month treatment. More high quality randomized controlled trials and cases should still be needed to warrant the results of this study.

Diffuse reflectance spectroscopy, a potential optical sensing technology for the detection of cortical breaches during spinal screw placement

Safe and accurate placement of screws remains a critical issue in open and minimally invasive spine surgery. We propose to use diffuse reflectance (DR) spectroscopy as a sensing technology at the tip of a surgical instrument to ensure a safe path of the instrument through the cancellous bone of the vertebrae. This approach could potentially reduce the rate of cortical bone breaches, thereby resulting in fewer neural and vascular injuries during spinal fusion surgery. In our study, DR spectra in the wavelength ranges of 400 to 1600 nm were acquired from cancellous and cortical bone from three human cadavers. First, it was investigated whether these spectra can be used to distinguish between the two bone types based on fat, water, and blood content along with photon scattering. Subsequently, the penetration of the bone by an optical probe was simulated using the Monte-Carlo (MC) method, to study if the changes in fat content along the probe path would still enable distinction between the bone types. Finally, the simulation findings were validated via an experimental insertion of an optical screw probe into the vertebra aided by x-ray image guidance. The DR spectra indicate that the amount of fat, blood, and photon scattering is significantly higher in cancellous bone than in cortical bone (p  <  0.01), which allows distinction between the bone types. The MC simulations showed a change in fat content more than 1 mm before the optical probe came in contact with the cortical bone. The experimental insertion of the optical screw probe gave similar results. This study shows that spectral tissue sensing, based on DR spectroscopy at the instrument tip, is a promising technology to identify the transition zone from cancellous to cortical vertebral bone. The technology therefore has the potential to improve the safety and accuracy of spinal screw placement procedures.

Trends in the Use of Bone Morphogenetic Protein-2 in Adult Spinal Deformity Surgery: A 10-Year Analysis of 54 054 Patients

Background

Bone morphogenetic protein-2 (BMP-2) is an available bone graft option in spinal fusion surgery. The purpose of this study is to investigate the trends of BMP-2 utilization in adult spinal deformity (ASD) surgery.

Methods

The Nationwide Inpatient Sample database from 2002 to 2011 was reviewed. Inclusion criteria were patients over 18 years of age who underwent spinal fusion for ASD. Trends of BMP-2 use were examined over time, as well as stratified based on patient and surgical characteristics. All analyses were done after application of discharge weights to produce national estimates.

Results

There were 54 054 patients who met inclusion criteria and were included in this study. The overall rate of BMP-2 use was 39.7% (95% confidence interval 35.0%- 44.3%). Overall, there was steady increase in its use over time, with the highest peak in 2009 (55.3% of all cases used BMP-2), and then a decrease up to 37.9% in 2011 (P < .001). The rate of BMP-2 use was significantly higher for patients older than 54 years of age (compared to patients <54, P < .001). It was also higher in females (P = .009), Caucasian patients (P = .006), and Medicare patients (P = .006). Its use was 28.6% in the Northeast, 38.1% in the South, 45.2% in the Midwest, and 48.2% in the West (P = .035). Circumferential procedures had the highest rate of BMP-2 use (44.3%, P = .045). Average total hospital charges were $152,403 ± 117,454 for patients who did not receive BMP-2 and $205,426 ± 137,561 for patients who did (P < .001).

Conclusion

After analysis of a large nationwide database, it was found that the rate of BMP-2 use in ASD surgery is approximately 40%. There was a significant increase in use from 2002 to 2009, and a decrease thereafter. The highest rates of use were found in older patients, female patients, white patients, Medicare patients, circumferential approaches, and patients undergoing surgery in the Midwest and West regions.

The Rothman Index as a predictor of postdischarge adverse events after elective spine surgery

BACKGROUND CONTEXT

The Rothman Index (RI) is a comprehensive rating of overall patient condition in the hospital setting. It is used at many medical centers and calculated based on vital signs, laboratory values, and nursing assessments in the electronic medical record. Previous research has demonstrated an association with adverse events, readmission, and mortality in other fields, but it has not been investigated in spine surgery.

PURPOSE

The present study aims to determine the potential utility of the RI as a predictor of adverse events after discharge following elective spine surgery.

STUDY DESIGN/SETTING

This retrospective cohort study was carried out at a large academic medical center.

PATIENT SAMPLE

A total of 2,687 patients who underwent elective spine surgery between 2013 and 2016 were included in the present study.

OUTCOME MEASURES

The occurrence of adverse events and readmission after discharge from the hospital, within postoperative day 30, was determined in the present study.

METHODS

Patient characteristics and 30-day perioperative outcomes were characterized, with events being classified as "major adverse events" or "minor adverse events" using standardized criteria. Rothman Index scores from the hospitalization were analyzed and compared for those who did or did not experience adverse events after discharge. The association of lowest and latest scores on adverse events was determined with multivariate regression, controlling for demographics, comorbidities, surgical procedure, and length of stay.

RESULTS

Postdischarge adverse events were experienced by 7.1% of patients. The latest and lowest RI values were significantly inversely correlated with any adverse events, major adverse events, minor adverse events and readmissions after controlling for age, gender, body mass index, American Society of Anesthesiologists (ASA) class, surgical site, and hospital length of stay. Rates of readmission and any adverse event consistently had an inverse correlation with lowest and latest RI scores, with patients at increased risk with lowest score below 65 or latest score below 85.

CONCLUSIONS

The RI is a tool that can be used to predict postdischarge adverse events after elective spine surgery that adds value to commonly used indices such as patient demographics and ASA. It is found that this can help physicians identify high-risk patients before discharge and should be able to better inform clinical decisions.

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.

Critical analysis of trends in lumbar fusion for degenerative disorders revisited: influence of technique on fusion rate and clinical outcomes

PURPOSE

Lumbar fusion for degenerative disorders is among the most common spine surgical procedures performed. The purpose of this study was to analyze fusion, complications, and clinical success for lumbar fusion performed with various surgical techniques as reported in the literature from 2000 to 2015 and compare with previous critical analysis of outcomes from 1980 to 2000.

METHODS

A systematic review of the literature to identify all studies of adult lumbar fusion for degenerative disorders published between January 1, 2000, and August 31, 2015, was performed adhering to PRISMA guidelines. Studies were included if they enabled analysis of outcomes of individual fusion techniques.

RESULTS

Data from 8599 patients extracted from 160 studies were recorded. Posterior and transforaminal lumbar interbody fusion (PLIF and TLIF) had significantly higher fusion rates compared to instrumented posterolateral fusion (PLF) (OR 3.20 and 2.46, respectively). Clinical success rate was statistically higher with MIS versus non-MIS fusion (OR 2.44). While methodological quality was higher in studies from 2000 to 2015 than prior decades, the outcomes of comparable procedures were about the same.

CONCLUSIONS

Lumbar fusions for degenerative disorders from 2000 to 2015 demonstrate a trend toward more interbody fusions and MIS techniques than prior decades. Clinical success with MIS appears more likely than with non-MIS fusions, despite equivalent fusion and complication rates. While these data are intriguing, they should be interpreted cautiously considering the level of heterogeneity of the studies available. Further, high-quality comparative studies are warranted to better understand the relative benefits of more complex interbody and MIS fusions for these conditions. These slides can be retrieved under Electronic Supplementary Material.

Circumferential fusion: a comparative analysis between anterior lumbar interbody fusion with posterior pedicle screw fixation and transforaminal lumbar interbody fusion for L5-S1 isthmic spondylolisthesis

BACKGROUND CONTEXT

Transforaminal lumbar interbody fusion (TLIF) or anterior lumbar interbody fusion with percutaneous pedicle screws (ALIFPS) offer significantly higher radiographic fusion rates than other fusion techniques for L5-S1 isthmic spondylolisthesis (IS). As it stands, there is a relative paucity of comparative data of the two techniques.

PURPOSE

To define the clinical, radiographic, and financial differences between TLIF and ALIFPS for L5-S1 IS.

DESIGN/SETTING

A retrospective cohort study conducted at a single tertiary care center.

PATIENT SAMPLE

Sixty-six patients who underwent either TLIF or ALIPFS for L5-S1 IS at a single tertiary care center between 2009 and 2014.

OUTCOME MEASURES

Quality of life outcome scores including the EuroQol-5 Dimensions (EQ-5D), Pain Disability Questionnaire (PDQ), and Patient Health Questionnaire-9 (PHQ-9). Sagittal balance parameters including: pelvic incidence, pelvic tilt, sacral slope, segmental lordosis, total lordosis, degree of slip, disc height, and L1-axis S1 distance (LASD). Cost measures included in-hospital charges, hospital length of stay (LOS), and post-admission costs accrued over 1 year.

METHODS

Quality of life (QoL) outcome scores, radiographic data, and financial data were collected with a minimum of 1-year follow-up. Clinical results were investigated using the PDQ, PHQ-9, and EQ-5D. Radiographic measurements included lumbar lordosis, segmental lordosis, pelvic tilt, pelvic incidence, height of disc, L-1 axis S-1 distance, and the degree of slip. Cost data were generated based on patient-level resource utilization. Comparative data were presented as median with interquartile range (IQR). Continuous variables were compared using either independent Student t tests assuming unequal variance or Mann-Whitney U tests for parametric and nonparametric variables, respectively. The minimally clinical important difference (MCID) used for each questionnaire was as follows: PDQ (26), PHQ-9 (5), and EQ-5D (0.4).

RESULTS

A total of 66 patients met inclusion criteria. In the ALIFPS cohort, PDQ scores improved from 69 [47, 82] to 26 [18.2, 79.7], p=.02. In the TLIF cohort, PDQ scores improved from 73 [46, 85] to 48.5 [23, 67.5], p=.01. Both groups also showed a significant improvement in EQ-5D scores at 1 year, but the ALIFPS group showed a significantly greater improvement in EQ-5D scores at 1 year (0.1 [0,0.2] vs. 0.2 [0.1, 0.4], p=.02). Furthermore, only the ALIFPS cohort showed a significant improvement in segmental lordosis. The ALIFPS cohort showed a significantly greater improvement in disc height than did TLIF (3.5 [2, 5.5] vs. 6.7 [4.1, 10], p=.01). No significant differences were found in the direct costs of both procedures.

CONCLUSIONS

Our findings suggest that anterior lumbar interbody fusion with percutaneous pedicle screws can achieve better clinical outcomes compared with TLIF for the treatment of IS. We believe the superior radiographic outcomes achieved through ALIFPS, namely a greater restoration of segmental lordosis and disc height, may have contributed to the improved clinical outcomes presented in the current study.

Indication Variability in Degenerative Lumbar Spine Surgery: A Four-nation Survey

STUDY DESIGN

Electronic survey.

OBJECTIVE

The aim of this study was to identify the international nuances in surgical treatment patterns for severals lumbar degenerative conditions, specifically, to identify differences in responses in each country groupand different treatment trends across countries.

SUMMARY OF BACKGROUND DATA

Significant variations in treatment of lumbar degenerative conditions exist among spine surgeons, related to the lack of established consensus in the literature.

METHODS

An online survey with preformulated answers was submitted to 52 orthopedic surgeons, 50 neurosurgeons from four different countries (United States, France, Spain, and Germany) regarding five vignette-cases. Cases included: multilevel stenosis, monolevel stenosis, lytic spondylolisthesis, isthmic lysis, and degenerative scoliosis. The variability for each country was calculated according to the Index of Qualitative Variation (IQV = 0: no variability and 1: maximal variability). We used Fleiss kappa (range: from -1, poor agreement, to 1, almost perfect agreement) for assessing the reliability of agreement between the participants concerning specialties, countries, and age groups.

RESULTS

For the two stenosis cases, US surgeons were more likely to propose decompression (IQV multilevel = 0.47 and monolevel = 0.32) comparing with European countries more heterogeneous (all IQV >0.70) and more frequently proposing fusion. As regards degenerative scoliosis, all attitudes were extremely heterogeneous with IQV >0.8. Fusion for isthmic spondylolisthesis was more consensual (all IQV <0.63), but attitudes were more heterogeneous for isthmic lysis (IQV ranged from 0.48 to 0.76) with anterior approach proposed in France (37%) and United States (19.2%).The overall interrater agreement was equally slight not only for neurosurgeons (Fleiss Kappa = 0.04) and orthopedic surgeons (Kappa = 0.13), but also for countries (Kappa <0.13) and age groups (Kappa <0.1).

CONCLUSION

In this study, we found substantial agreement for some spinal conditions but a high variability in some others: intranational and international variations were observed, reflecting the lack of literature consensus.

LEVEL OF EVIDENCE

2.

Different Fusion Approaches for Single-level Lumbar Spondylolysis Have Similar Perioperative Outcomes

STUDY DESIGN

Retrospective cohort study OBJECTIVE.: The aim of this study was to compare perioperative adverse events for patients with lumbar spondylolysis treated with transforaminal lumbar interbody fusion (TLIF), posterior spinal fusion (PSF), combined anterior and posterior fusion (AP fusion), or anterior lumbar interbody fusion (ALIF).

SUMMARY OF BACKGROUND DATA

Previous cohort studies have shown similar long-term outcomes for different surgical approaches for this indication, but potential differences in 30-day perioperative adverse events have not been well characterized.

METHODS

The present study uses data extracted from the American College of Surgeons National Surgical Quality Improvement Database. Patients undergoing fusion with different approaches for lumbar spondylolysis were identified. Propensity score matching was utilized to account for potential differences in demographic and comorbidity factors. Comparisons among perioperative outcomes were then made among the propensity score-matched study groups.

RESULTS

Of 1077 cases of spondylolysis identified, 556 underwent TLIF, 327 underwent PSF, 108 underwent AP fusion, and 86 underwent ALIF. After propensity score matching, there were no differences in the rates of any of the 30-day individual adverse events studied and no differences in the aggregated groupings of any adverse event, serious adverse event, or minor adverse event. There was a significantly increased operative time in the AP fusion group, but there were no differences in hospital length of stay or readmission rates.

CONCLUSION

Because perioperative adverse event rates were similar, even with a slightly longer operative time in the AP fusion group, these findings suggest that surgeon preference and long-term outcomes are better used to determine the recommendation of one surgical approach over another for single level fusions for lumbar spondylolysis.

LEVEL OF EVIDENCE

3.

A novel noninstrumented surgical approach for foramen reconstruction for isthmic spondylolisthesis in patients with radiculopathy: preliminary clinical and radiographic outcomes

OBJECTIVE The health care costs for instrumented spine surgery have increased dramatically in the last few decades. The authors present a novel noninstrumented surgical approach for patients with isthmic spondylolisthesis, with clinical and radiographic results. METHODS Charts of patients who underwent this technique were reviewed. The procedure consisted of nerve root decompression by reconstruction of the intervertebral foramen. This was achieved by removal of the pedicle followed by noninstrumented posterolateral fusion in which autologous bone graft from the right iliac crest was used. Outcomes regarding radicular complaints, bony fusion, progression of the slip, and complications were evaluated using patient history and radiographs obtained at follow-up intervals of 3-18 months after surgery. RESULTS A total of 58 patients with a mean age of 47 years were treated with this method. Partial removal of the pedicle was performed in 93.1% of the cases, whereas in 6.9% of the cases the entire pedicle was removed. The mean duration of surgery was 216.5 ± 54.5 minutes (range 91-340 minutes). The mean (± SD) duration of hospitalization was 10.1 ± 2.9 days (range 5-18 days). After 3 months of follow-up, 86% of the patients reported no leg pain, and this dropped to 81% at last follow-up. Radiographic follow-up showed bony fusion in 87.7% of the patients. At 1 year, 5 patients showed progression of the slip, which in 1 patient prompted a second operation within 1 year. No major complications occurred. CONCLUSIONS Treatment of isthmic spondylolisthesis by reconstruction of the intervertebral neuroforamen and posterolateral fusion in situ is a safe procedure and has comparable results with the existing techniques. Cost-effectiveness research comparing this technique to conventional instrumented fusion techniques is necessary to evaluate the merits for both patients and society.

Outcomes of Posterolateral Fusion with and without Instrumentation and of Interbody Fusion for Isthmic Spondylolisthesis: A Prospective Study

BACKGROUND

Various methods for the treatment of isthmic spondylolisthesis are available. The aim of this study was to compare outcomes after posterolateral fusion without instrumentation, posterolateral fusion with instrumentation, and interbody fusion.

METHODS

The Swedish Spine Register was used to identify 765 patients who had been operated on for isthmic spondylolisthesis and had at least preoperative and 2-year outcome data; 586 of them had longer follow-up (a mean of 6.9 years). The outcome measures were a global assessment of leg and back pain, the Oswestry Disability Index (ODI), the EuroQol-5 Dimensions (EQ-5D) Questionnaire, the Short Form-36 (SF-36), a visual analog scale (VAS) for back and leg pain, and satisfaction with treatment. Data on additional lumbar spine surgery was searched for in the register, with the mean duration of follow-up for this variable being 10.6 years after the index procedure. Statistical analyses were performed with analysis of covariance or competing-risks proportional hazards regression, adjusted for baseline differences in the studied variables, smoking, employment status, and level of fusion.

RESULTS

Posterolateral fusion without instrumentation was performed in 102 patients; posterolateral fusion with instrumentation, in 452; and interbody fusion, in 211. At 1 year, improvement was reported in the global assessment for back pain by 54% of the patients who had posterolateral fusion without instrumentation, 68% of those treated with posterolateral fusion with instrumentation, and 70% of those treated with interbody fusion (p = 0.009). The VAS for back pain and reported satisfaction with treatment showed similar patterns (p = 0.003 and p = 0.017, respectively), whereas other outcomes did not differ among the treatment groups at 1 year. At 2 years, the global assessment for back pain indicated improvement in 57% of the patients who had undergone posterolateral fusion without instrumentation, 70% of those who had posterolateral fusion with instrumentation, and 71% of those treated with interbody fusion (p = 0.022). There were no significant outcome differences at the mean 6.9-year follow-up interval. There was an increased hazard ratio for additional lumbar spine surgery after interbody fusion (4.34; 95% confidence interval [CI] = 1.71 to 11.03) and posterolateral fusion with instrumentation (2.56; 95% CI = 1.02 to 6.42) compared with after posterolateral fusion without instrumentation (1.00; reference).

CONCLUSIONS

Fusion with instrumentation, with or without interbody fusion, was associated with more improvement in back pain scores and higher satisfaction with treatment compared with fusion without instrumentation at 1 year, but the difference was attenuated with longer follow-up. Fusion with instrumentation was associated with a significantly higher risk of additional spine surgery.

LEVEL OF EVIDENCE

Therapeutic Level III. See Instructions for Authors for a complete description of levels of evidence.