Transforaminal versus anterior lumbar interbody fusion in long deformity constructs: a matched cohort analysis

Pedicle Subtraction Osteotomy Versus Multilevel Anterior Lumbar Interbody Fusion and Lateral Lumbar Interbody Fusion in the Treatment of Adult Spinal Deformity: Trends, Outcomes, and Cost

STUDY DESIGN

Retrospective cohort study.

OBJECTIVE

The aim of this study was to compare the outcomes of pedicle subtraction osteotomy (PSO) with multilevel anterior lumbar interbody fusion (ALIF) and lateral lumbar interbody fusion (LLIF) in posterior long-segment fusion.

BACKGROUND

PSO and ALIF/LLIF are 2 techniques used to restore lumbar lordosis and correct sagittal alignment, with each holding its unique advantages and disadvantages. As there are situations where both techniques can be employed, it is important to compare the risks and benefits of both.

PATIENTS AND METHODS

Patients aged 18 years or older who underwent PSO or multilevel ALIF/LLIF with posterior fusion of 7-12 levels and pelvic fixation were identified. 1:1 propensity score was used to match PSO and ALIF/LLIF cohorts for age, sex, and relevant comorbidities, including smoking status. Logistic regression was used to compare medical and surgical outcomes. Trends and costs were generated for both groups as well.

RESULTS

ALIF/LLIF utilization in posterior long fusion has been steadily increasing since 2010, whereas PSO utilization has significantly dropped since 2017. PSO was associated with an increased risk of durotomy ( P < 0.001) and neurological injury ( P = 0.018). ALIF/LLIF was associated with increased rates of postoperative radiculopathy ( P = 0.005). Patients who underwent PSO had higher rates of pseudarthrosis within 1 and 2 years ( P = 0.015; P = 0.010), 1-year hardware failure ( P = 0.028), and 2-year reinsertion of instrumentation ( P = 0.009). Reoperation rates for both approaches were not statistically different at any time point throughout the 5-year period. In addition, there were no significant differences in both procedural and 90-day postoperative costs.

CONCLUSIONS

PSO was associated with higher rates of surgical complications compared with anterior approaches. However, there was no significant difference in overall reoperation rates. Spine surgeons should select the optimal technique for a given patient and the type of lordotic correction required.

Analysis of the Frequency of Intraoperative Complications in Anterior Lumbar Interbody Fusion: A Systematic Review

OBJECTIVE

We assessed the frequency of intraoperative complication rates related to access surgery, operating time, and intraoperative bleeding rates described in the literature for patients undergoing anterior lumbar interbody fusion (ALIF) to evaluate the adverse effects and, thus, help in therapeutic decision making and contribute to future clinical trials.

METHODS

A systematic review was conducted of MEDLINE and Embase databases in March 2023. The main inclusion criteria were adult patients aged >18 years, with no maximum age limit; the use of ALIF; the presence of quantitative data on intraoperative complications; and randomized controlled trials and cohort studies. Vascular and peritoneal injuries were considered primary endpoints. The operative time and intraoperative bleeding rate were secondary endpoints. Reports and case series, case-control series, systematic reviews, and meta-analyses were excluded.

RESULTS

Eight studies were included with a total of 2395 patients. We found important quantitative data for future randomized clinical studies involving ALIF surgery, including the rate of vascular lesions (2.79%) and peritoneal lesions (0.37%). In addition to these factors, only 4 of the 8 studies addressed the average surgery time, with a total average of 145.61 minutes. Furthermore, 6 of the 8 articles reported the mean rate of intraoperative bleeding, with a total mean blood loss of 272.75 mL.

CONCLUSIONS

ALIF is a lumbar spine access technique with low intraoperative complications. Patients with contraindications have a higher risk of complications. Randomized clinical trials are needed to assess the efficacy and safety of the procedure.

Long-term comparison of anterior (ALIF) versus transforaminal (TLIF) lumbar interbody fusion: a propensity score-matched register-based study

PURPOSE

Anterior (ALIF) and transforaminal (TLIF) lumbar interbody fusion have shown similar clinical outcomes at short- and medium-term follow-ups. Possible advantages of ALIF in the long run could be better disc height and lumbar lordosis and reduced risk of adjacent segment disease. We aimed to study if ALIF could be associated with superior clinical outcomes than TLIF at long-term follow-up.

METHODS

We analysed 535 patients treated with ALIF or TLIF of the L5-S1 spinal segment between 2007 and 2017 who completed long-term follow-up in a national spine registry database (NORspine). We defined treatment success after surgery as at least 30% improvement in Oswestry Disability Index (ODI) at long-term follow-up. Patients treated with ALIF and TLIF and who responded at long term were balanced by propensity score matching. The proportions of successfully treated patients within each group were compared by numbers and percentages with corresponding relative risk.

RESULTS

The mean (95%CI) age of the total study population was 50 (49-51) years, and 264 (49%) were females. The mean (95%CI) preoperative ODI score was 40 (39-42), and 174 (33%) had previous spine surgery. Propensity score matching left 120 patients in each treatment group. At a median (95%CI) of 92 (88-97) months after surgery, we found no difference in proportions successfully treated patients with ALIF versus TLIF (68 (58%) versus 77 (65%), RR (95%CI) = 0.88 (0.72 to1.08); p = 0.237).

CONCLUSIONS

This propensity score-matched national spine register study of patients treated with ALIF versus TLIF of the lumbosacral junction found no differences in proportions of successfully treated patients at long-term follow-up.

LEVEL OF EVIDENCE I

Diagnostic: individual cross-sectional studies with the consistently applied reference standard and blinding.

Approaches in Anterior Column Support in Adult Spinal Deformity Surgery: A Meta-Analysis of Clinical and Radiologic Outcomes

OBJECTIVE

This meta-analysis was conducted to compare anterior lumbar interbody fusion (ALIF) with transforaminal lumbar interbody fusion (TLIF) in terms of postoperative complications, improvement in radiographic parameters, and patient-reported outcomes.

METHODS

PubMed, Cochrane, and Google Scholar (pages 1-20) databases were searched up to June 2023. The studied outcomes were the rate of rod failures, rod failures requiring revision surgery, all complications, all revision surgeries, the change in pelvic tilt, sacral slope, Cobb angle, lumbar lordosis (LL), sagittal vertical axis, the postoperative pelvic incidence-LL, and LL, and the improvement in back pain and Oswestry Disability Index (ODI).

RESULTS

Six studies were included in this meta-analysis. ALIF showed higher postoperative lordosis (P = 0.003) and better improvement in ODI (P = 0.0001). No difference was seen in the remaining outcomes between ALIF and TLIF.

CONCLUSIONS

Although ALIF had better improvement in ODI, the mean difference was 6.5 points, which is below the minimal clinically important difference, stripping this result of any clinical value. Furthermore, even though ALIF had better postoperative lordosis, the change in LL postoperatively was not different between ALIF and TLIF. With no difference in complications, sagittal and coronal alignment, and patient-reported outcomes, TLIF was shown in this study to be favored instead of ALIF in adult spinal deformity surgery to avoid all the double approach-related comorbidity.

Clinical and Radiologic Analysis of Minimally Invasive Anterior-Posterior Combined Surgery for Adult Spinal Deformity: Comparison of Oblique Lateral Interbody Fusion at L5/S1 (OLIF51) versus Transforaminal Interbody Fusion

Background and Objectives: Although adult spinal deformity (ASD) surgery brought about improvement in the quality of life of patients, it is accompanied by high invasiveness and several complications. Specifically, mechanical complications of rod fracture, instrumentation failures, and pseudarthrosis are still unsolved issues. To better improve these problems, oblique lateral interbody fusion at L5/S1 (OLIF51) was introduced in 2015 at my institution. The objective of this study was to compare the clinical and radiologic outcomes of anterior-posterior combined surgery for ASD between the use of OLIF51 and transforaminal interbody fusion (TLIF) at L5/S1. Materials and Methods: A total of 117 ASD patients received anterior-posterior correction surgeries either with the use of OLIF51 (35 patients) or L5/S1 TLIF (82 patients). In both groups, L1-5 OLIF and minimally invasive posterior procedures of hybrid or circumferential MIS were employed. The sagittal and coronal spinal alignment and spino-pelvic parameters were recorded preoperatively and at follow-up. The quality-of-life parameters and visual analogue scale were evaluated, as well as surgical complications at follow-up. Results: The average follow-up period was thirty months (13-84). The number of average fused segments was eight (4-12). The operation time and estimated blood loss were significantly lower in OLIF51 than in TLIF. The PI-LL mismatch, LLL, L5/S1 segmental lordosis, and L5 coronal tilt were significantly better in OLIF51 than TLIF. The complication rate was statistically equivalent between the two groups. Conclusions: The introduction of OLIF51 for adult spine deformity surgery led to a decrease in operation time and estimated blood loss, as well as improvement in sagittal and coronal correction compared to TLIF. The circumferential MIS correction and fusion with OLIF51 serve as an effective surgical modality which can be applied to many cases of adult spinal deformity.

The "Sandwich" Extended Pedicle Subtraction Osteotomy for the Treatment of Fixed Sagittal Malalignment: Technical Description, Case Series, and Early Results With 2-Year Outcomes

BACKGROUND AND OBJECTIVES

Adult spinal deformity (ASD) with fixed sagittal malalignment (FSM) may require a pedicle subtraction osteotomy (PSO) for greater focal lordosis and restoration of global alignment. Despite growing trends in minimizing PSOs given their associated high risks, a considerable portion of patients with ASD still require a lumbar PSO most commonly because of iatrogenic flat back deformity. The purpose of this article is to describe a modified extended PSO technique with additional anterior column support coined the "sandwich" extended PSO (SE-PSO) to promote arthrodesis and report the outcomes in a consecutive case series.

METHODS

Patients with ASD treated with a lumbar SE-PSO at a single institution from 2015 to 2020 were analyzed. Complications, radiographic data, and patient-reported outcomes were compared preoperatively, at immediate postoperative follow-up, and at a 2-year postoperative follow-up (FU).

RESULTS

Fourteen patients who underwent revision operations for FSM were included. Improvements in segmental lordosis across the PSO site (14.8 ± 6.8 vs 39.9 ± 7.1, P < .0001), overall lumbar lordosis (14.6 ± 15.4 vs 44.6 ± 12.1, P < .0001), sacral slope (21.0 ± 10.5 31.1 ± 10.7, P = .0150), C7 sagittal vertical axis (140.1 ± 59.0 mm vs 35.9 ± 28.5, P < .0001), and spinopelvic mismatch (52.5 ± 21.3 vs 18.6 ± 14.1, P = .0001) were obtained in all patients. Eight patients experienced perioperative complications, with intraoperative durotomy being the most common (n = 7). Eight patients had a 2-year FU and demonstrated improvements in their segmental lordosis across the PSO site (14.3 ± 7.0 vs 41.3 ± 7.3, P = .0003), overall lumbar lordosis (8.7 ± 17.8 vs 46.1 ± 14.2, P = .0014), sacral slope (19.1 ± 12.8 vs 32.3 ± 12.5, P = .0479), C7 sagittal vertical axis (173.6 ± 54.4 mm vs 35.8 ± 30.0, P < .0001), and spinopelvic mismatch (63.0 ± 19.7 vs 21.1 ± 18.3, P < .0001), all of which were maintained at final FU (P > .05). At 2 years, a significant increase in Scoliosis Research Society-22r total score (2.5 ± 0.8 vs 3.6 ± 0.7, P = .0023 was reported. There were no reports of symptomatic pseudarthrosis or mechanical complications.

CONCLUSION

SE-PSO is an effective technique to correct FSM and is associated with low complications, improved patient-reported outcomes, and spinopelvic parameters that are maintained at 2 years.

TLIF is Associated With Lower Rates of Adjacent Segment Disease and Complications Compared to ALIF: A Matched-Cohort Analysis

STUDY DESIGN

Retrospective cohort.

OBJECTIVE

To compare the rate of adjacent segment disease (ASD) in patients undergoing anterior lumbar interbody fusion (ALIF) versus transforaminal lumbar interbody fusion (TLIF) for the treatment of degenerative stenosis and spondylolisthesis.

SUMMARY OF BACKGROUND DATA

ALIF and TLIF are frequently used to treat Lumbar stenosis and spondylolisthesis. While both approaches have distinct advantages, it is unclear whether there are any differences in rates of ASD and postoperative complications.

METHODS

A retrospective cohort study of patients who underwent index 1-3 levels ALIF or TLIF between 2010 and 2022, using the PearlDiver Mariner Database, an all-claims insurance database (120 million patients). Patients with a history of prior lumbar surgery and those undergoing surgery for cancer, trauma, or infection were excluded. Exact 1:1 matching was performed using demographic factors, medical comorbidities, and surgical factors found to be significantly associated with ASD in a linear regression model. The primary outcome was a new diagnosis of ASD within 36 months of index surgery, and secondary outcomes were all-cause medical and surgical complications.

RESULTS

Exact 1:1 matching resulted in 2 equal groups of 106,451 patients undergoing TLIF and ALIF. The TLIF approach was associated with a lower risk of ASD (RR 0.58, 95% CI 0.56-0.59, P < 0.001) and all-cause medical complications (RR 0.94, 95% CI 0.91-0.98, P =0.002). All-cause surgical complications were not significantly different between both groups.

CONCLUSION

After 1:1 exact matching to control for confounding variables, this study suggests that for patients with symptomatic degenerative stenosis and spondylolisthesis, a TLIF procedure (compared to ALIF) is associated with a decreased risk of developing ASD within 36 months of index surgery. Future prospective studies are needed to corroborate these findings.

LEVEL OF EVIDENCE

Level-3.

Comparison of Lumbosacral Fusion Grade in Patients after Transforaminal and Anterior Lumbar Interbody Fusion with Minimum 2-Year Follow-Up

OBJECTIVE

Generally, anterior lumbar interbody fusion (ALIF) was believed superior to transforaminal lumbar interbody fusion (TLIF) in induction of fusion. However, many studies have reported comparable results in lumbosacral fusion rate between the two approaches. This study aimed to evaluate the realistic lumbosacral arthrodesis rates following ALIF and TLIF in patients with degenerative spondylolisthesis as measured by CT and radiology.

METHODS

Ninety-six patients who underwent single-level L5-S1 fusion through ALIF (n = 48) or TLIF (n = 48) for degenerative spondylolisthesis at the Spine Center, University of California San Francisco, between October 2014 and December 2017 were retrospectively evaluated. Fusion was independently evaluated and categorized as solid fusion, indeterminate fusion, or pseudarthroses by two radiologists using the modified Brantigan-Steffee-Fraser (mBSF) grade. Clinical data on sex, age, body mass index, Meyerding grade, smoking status, follow-up times, complications, and radiological parameters including disc height, disc angle, segmental lordosis, and overall lumbar lordosis were collected. The fusion results and clinical and radiographic data were statistically compared between the ALIF and TLIF groups by using t-test or chi-square test.

RESULTS

The mean follow-up period was 37.5 (ranging from 24 to 51) months. Clear, solid radiographic fusions were higher in the ALIF group compared with the TLIF group at the last follow-up (75% vs 47.9%, p = 0.006). Indeterminate fusion occurred in 20.8% (10/48) of ALIF cases and in 43.8% (21/48) of TLIF cases (p = 0.028). Radiographic pseudarthrosis was not significantly different between the TLIF and ALIF groups (16.7% vs 8.3%; p = 0.677). In subgroup analysis of the patients without bone morphogenetic protein (BMP), the solid radiographic fusion rate was significantly higher in the ALIF group than that in the TLIF group (78.6% vs 45.5%; p = 0.037). There were no differences in sex, age, body mass index, Meyerding grade, smoking status, or follow-up time between the two groups (p > 0.05). The ALIF group had more improvement in disc height (7.8 mm vs 4.7 mm), disc angle (5.2° vs 1.5°), segmental lordosis (7.0° vs 2.5°), and overall lumbar lordosis (4.7° vs 0.7°) compared with the TLIF group (p < 0.05). Overall complication rates were similar between the TLIF and ALIF groups (10.4% vs 8.33%; p > 0.999).

CONCLUSIONS

With a minimum 2-year radiographic analysis of arthrodesis at lumbosacral level by radiologists, the rate of solid radiographic fusions was higher in the ALIF group compared with the TLIF group, whereas the TLIF group had a higher rate of indeterminate fusion. Radiographic pseudarthrosis did not differ significantly between the TLIF and ALIF groups.

Predictors of Postoperative Segmental and Overall Lumbar Lordosis in Minimally Invasive Transforaminal Lumbar Interbody Fusion: A Consecutive Case Series

STUDY DESIGN

Retrospective Case-Series.

OBJECTIVES

Due to heterogeneity in previous studies, the effect of MI-TLIF on postoperative segmental lordosis (SL) and lumbar lordosis (LL) remains unclear. Therefore, we aim to identify radiographic factors associated with lordosis after surgery in a homogenous series of MI-TLIF patients.

METHODS

A single-center retrospective review identified consecutive patients who underwent single-level MI-TLIF for grade 1 degenerative spondylolisthesis from 2015-2020. All surgeries underwent unilateral facetectomies and a contralateral facet release with expandable interbody cages. PROs included the ODI and NRS-BP for low-back pain. Radiographic measures included SL, disc height, percent spondylolisthesis, cage positioning, LL, PI-LL mismatch, sacral-slope, and pelvic-tilt. Surgeries were considered "lordosing" if the change in postoperative SL was ≥ +4° and "kyphosing" if ≤ -4°. Predictors of change in SL/LL were evaluated using Pearson's correlation and multivariable regression.

RESULTS

A total of 73 patients with an average follow-up of 22.5 (range 12-61) months were included. Patients experienced significant improvements in ODI (29% ± 22% improvement, P < .001) and NRS-BP (3.3 ± 3 point improvement, P < .001). There was a significant increase in mean SL (Δ3.43° ± 4.37°, P < .001) while LL (Δ0.17° ± 6.98°, P > .05) remained stable. Thirty-eight (52%) patients experienced lordosing MI-TLIFs, compared to 4 (5%) kyphosing and 31 (43%) neutral MI-TLIFs. A lower preoperative SL and more anterior cage placement were associated with the greatest improvement in SL (β = -.45° P = .001, β = 15.06° P < .001, respectively).

CONCLUSIONS

In our series, the majority of patients experienced lordosing or neutral MI-TLIFs (n = 69, 95%). Preoperative radiographic alignment and anterior cage placement were significantly associated with target SL following MI-TLIF.

The anatomical feasibility of anterior intra- and extra-bifurcation approaches to L5-S1: an anatomic study based on lumbar MRI

BACKGROUND CONTEXT

The anterior approach at L5-S1 has many advantages, however, vascular complications are challenging for spinal surgeons who may not be familiar with the variability of vascular anatomy. There are three different anterior approaches (intra-bifurcation approach and extra-bifurcation: left-, and right-sided prepsoas approaches) described in previous studies to respond to the variability of anterior vascular anatomy for reduction in vascular injury, while no guidance for the choice of approach preoperatively.

PURPOSE

To analyze the anatomical feasibility of three anterior approaches to access the L5-S1 disc space according to a practical framework.

STUDY DESIGN

Retrospective study.

PATIENT SAMPLE

Lumbar magnetic resonance imaging (MRI) from patients who visited our outpatient clinic were reviewed, with 150 cases meeting the inclusion criteria.

OUTCOME MEASURES

The following radiographic parameters were measured on axial T2-weighted MRI at the lower endplate of L5 and the upper endplate of S1: width of the vascular corridor, position of the left and right common iliac vein (CIV), and presence of perivascular adipose tissue (PAT). Moreover, we designed a safe line to evaluate the feasibility of left- and right-sided prepsoas approaches. Cases of lumbosacral transitional vertebrae were identified.

METHODS

The feasibility of the intra-bifurcation approach was determined by the width of the vascular corridor, presence of PAT, and the position of the CIV. The feasibility of the prepsoas approach was determined by the relative position of the CIV to the safe line, presence of PAT, and the intersection point of the CIV and vertebral body.

RESULTS

Sixty-eight percent, 64.7%, and 75.3% cases allowed the intra-bifurcation, left-, and right-sided prepsoas approach to L5-S1, respectively. The cases in this study had at least one of three anterior approaches to access L5-S1 disc space, and 74% of cases had more than one anatomical feasibility of anterior approach. The right-sided prepsoas approach was feasible in the majority of cases because of the vertical course of the right CIV with a significantly higher proportion of presence of PAT. Patients with lumbosacral transitional vertebrae (24 cases) may prefer the prepsoas approaches, and only six cases (25.0%) were determined to be feasible for the intra-bifurcation approach.

CONCLUSIONS

Our study proposes a practical framework to determine whether the three different anterior approaches are feasible access at L5-S1. According to the framework, all cases had the anatomical feasibility of using an anterior approach to access L5-S1, and three-fourths of cases had a replaceable anterior approach when encountering intraoperative difficulties.

Do On-Table Radiographs Predict Postoperative Sagittal Alignment after Posterior Lumbar Fusion?

OBJECTIVE

To determine if intraoperative on-table lumbar lordosis and segmental lordosis correlate with postoperative lordosis following single-level posterolateral decompression and fusion (PLDF) or transforaminal lumbar interbody fusion (TLIF).

METHODS

Electronic medical records were reviewed for patients ≥18 years old who underwent PLDF or TLIF between 2012 and 2020. Lumbar lordosis and segmental lordosis were compared between pre-, intra-, and postoperative radiographs using paired t tests. Significance was set at P < 0.05.

RESULTS

A total of 200 patients met inclusion criteria. No significant differences in preoperative, intraoperative, or postoperative measurements were found between groups. Patients who underwent PLDF experienced less disc height loss over 1 year postoperatively (PLDF: 0.45 ± 0.9 mm vs. TLIF: 1.2 ± 1.4 mm, P < 0.001). Lumbar lordosis significantly decreased between intraoperative to postoperative radiographs at 2-6 weeks for PLDF (Δ: -4.0°, P < 0.001) and TLIF (Δ: -5.6°, P < 0.001), but no change was identified between the intraoperative and >6 month postoperative radiographs for PLDF (Δ: -0.3°, P = 0.634) or TLIF (Δ: -1.6°, P = 0.087). Segmental lordosis significantly increased from the preoperative to post-instrumentation intraoperative radiographs for PLDF (Δ: 2.7°, P < 0.001) and TLIF (Δ: 1.8°, P < 0.001), but it subsequently decreased at the final follow up for PLDF (Δ: -1.9°, P < 0.001) and TLIF (Δ: -2.3°, P < 0.001).

CONCLUSIONS

Subtle decreases in lumbar lordosis may be noticed in early postoperative radiographs compared with intraoperative images on Jackson operative tables. However, these changes are not present at 1-year follow-up as lumbar lordosis increases to a similar level as intraoperative fixation.

Comparison of C-Arm-Free Oblique Lumbar Interbody Fusion L5-S1 (OLIF51) with Transforaminal Lumbar Interbody Fusion L5-S1 (TLIF51) for Adult Spinal Deformity

Background and Objectives: Adult spinal deformity (ASD) surgery, L5-S1 lordosis is very important factor. The main objective of the research is to retrospectively compare symptomatic presentation and radiological presentation in the sequelae of oblique lumbar inter-body spinal fusion at L5-S1 (OLIF51) and transforaminal lumbar interbody fusion (TLIF) for ASD. Materials and Methods: We retrospectively evaluated 54 patients who underwent corrective spinal fusion for ASD between October 2019 and January 2021. Thirteen patients underwent OLIF51 (average 74.6 years old, group O) and 41 patients underwent TLIF51 (average 70.5 years old, group T). Mean follow-up period was 23.9 months for group O and 28.9 months for group T, ranging from 12 to 43 months. Clinical and radiographic outcomes are assessed using values including visual analogue scale (VAS) for back pain and Oswestry disability index (ODI). Radiographic evaluation was also collected preoperatively and at 6, 12, and 24 months postoperatively. Results: Surgical time in group O was less than that in group T (356 min vs. 492 min, p = 0.003). However, intraoperative blood loss of both groups were not significantly different (1016 mL vs. 1252 mL, p = 0.274). Changes in VAS and ODI were similar in both groups. L5-S1 angle gain and L5-S1 height gain in group O were significantly better than those of group T (9.4° vs. 1.6°, p = 0.0001, 4.2 mm vs. 0.8 mm, p = 0.0002). Conclusions: Clinical outcomes were not significantly different in both groups, but surgical time in OLIF51 was significantly less than that in TLIF51. The radiographic outcomes showed that OLIF51 created more L5-S1 lordosis and L5-S1 disc height compared with TLIF 51.

Lumbar Lordosis Correction With Transforaminal Lumbar Interbody Fusion in Adult Spinal Deformity Patients with Minimum 2-Year Follow-up

OBJECTIVE

To determine the degree of lumbar lordosis (LL) correction possible via transforaminal lumbar interbody fusion (TLIF) in adult spinal deformity patients.

METHODS

A retrospective chart review identified patients ≥18 years of age with severe positive sagittal balance defined by the SRS-Schwab classification: pelvic incidence to LL mismatch >20°, sagittal vertical axis >9.5cm, and/or pelvic tilt >30°. All patients had surgery between 2013 to 2018 with a TLIF at L4-L5 and/or L5-S1 by the senior author (J.L.F.) with ≥2-years follow-up.

RESULTS

Sixty-one patients (18 men, 43 women) with 85 TLIFs were included with an average age of 66 years and average follow-up of 50 months. Average lumbar lordosis (L1-S1) improved from 27° preoperative to 48° postoperative and 45° at 2-year follow-up (P < 0.001). Average segmental lordosis at L4-L5 TLIF sites improved from 3° preoperative to 13° postoperative and persisted at 2-year follow-up (P < 0.001). Segmental lordosis at L5-S1 TLIF sites improved from 7° preoperative to 21° postoperative and 20° at 2-year follow-up (P < 0.001). Seventeen of the TLIFs (20%) had >20° of segmental lordosis improvement at long-term follow-up. The rate of revision surgery for pseudoarthrosis at the TLIF level was 5%.

CONCLUSIONS

Significant lordosis correction can be achieved through an open TLIF in patients with severe positive sagittal balance when utilizing meticulous deformity correction techniques, avoiding the added morbidity of an anterior approach or a 3-column osteotomy.

Lordosis loss in degenerative spinal conditions

PURPOSE

To establish whether common degenerative lumbar spine conditions have a predictable sagittal profile and associated range of lordosis. The spinopelvic balance of a normal population and normal ranges are well described in the literature. There is also evidence that certain degenerative conditions can lead to a preponderance of loss of lordosis at specific spinal levels. There is limited literature on the range and magnitude of loss of lordosis for known degenerative lumbar spine pathologies.

METHODS

A retrospective analysis of prospectively obtained radiographs from a dual surgeon database was performed and imaging analysed for spinopelvic parameters. Degenerative conditions studied were; Lumbar degenerative spondylolisthesis (L3/4 and L4/5 analysed separately), L5/S1 degenerative disc disease, L5/S1 isthmic spondylolisthesis. Pelvic incidence, sacral slope, pelvic tilt, segmental and global lumbar lordosis, vertebral lordosis and lumbar vertical axis were measured.

RESULTS

The range of change in segmental lordosis was normally distributed for all studied degenerative spinal conditions except L5/S1 isthmic spondylolisthesis. L5/S1 degenerative disc disease affected younger adults (mean age 37), whilst degenerative spondylolisthesis at L3/4 and L4/5 affected older adults (mean ages 69.5 and 68.9 respectively). Removing an outlying high-grade L5/S1 isthmic spondylolisthesis made the data distribution approach a normal distribution.

CONCLUSION

Most degenerative spinal pathologies cause a normally distributed spectrum of deformity which should be addressed and corrected with a tailored, individualised surgical plan for each patient. Universal treatment recommendations should be interpreted with caution.

Failure in Adult Spinal Deformity Surgery: A Comprehensive Review of Current Rates, Mechanisms, and Prevention Strategies

STUDY DESIGN

Literature review.

OBJECTIVE

The aim of this review is to summarize recent literature on adult spinal deformity (ASD) treatment failure as well as prevention strategies for these failure modes.

SUMMARY OF BACKGROUND DATA

There is substantial evidence that ASD surgery can provide significant clinical benefits to patients. The volume of ASD surgery is increasing, and significantly more complex procedures are being performed, especially in the aging population with multiple comorbidities. Although there is potential for significant improvements in pain and disability with ASD surgery, these procedures continue to be associated with major complications and even outright failure.

METHODS

A systematic search of the PubMed database was performed for articles relevant to failure after ASD surgery. Institutional review board approval was not needed.

RESULTS

Failure and the potential need for revision surgery generally fall into 1 of 4 well-defined phenotypes: clinical failure, radiographic failure, the need for reoperation, and lack of cost-effectiveness. Revision surgery rates remain relatively high, challenging the overall cost-effectiveness of these procedures.

CONCLUSION

By consolidating the key evidence regarding failure, further research and innovation may be stimulated with the goal of significantly improving the safety and cost-effectiveness of ASD surgery.

Biomechanical study of rod stress in lumbopelvic fixation with lateral interbody fusion: an in vitro experimental study using synthetic bone models

OBJECTIVE

Despite improvements in surgical techniques and instruments, high rates of rod fracture following a long spinal fusion in the treatment of adult spinal deformity (ASD) remain a concern. Thus, an improved understanding of rod fracture may be valuable for better surgical planning. The authors aimed to investigate mechanical stress on posterior rods in lumbopelvic fixation for the treatment of ASD.

METHODS

Synthetic lumbopelvic bone models were instrumented with intervertebral cages, pedicle screws, S2-alar-iliac screws, and rods. The construct was then placed in a testing device, and compressive loads were applied. Subsequently, the strain on the rods was measured using strain gauges on the dorsal aspect of each rod.

RESULTS

When the models were instrumented using titanium alloy rods at 30° lumbar lordosis and with lateral interbody fusion cages, posterior rod strain was highest at the lowest segment (L5-S1) and significantly higher than that at the upper segment (L2-3) (p = 0.002). Changing the rod contour from 30° to 50° caused a 36% increase in strain at L5-S1 (p = 0.009). Changing the rod material from titanium alloy to cobalt-chromium caused a 140% increase in strain at L2-3 (p = 0.009) and a 28% decrease in strain at L5-S1 (p = 0.016). The rod strain at L5-S1 using a flat bender for contouring was 23% less than that obtained using a French bender (p = 0.016).

CONCLUSIONS

In lumbopelvic fixation in which currently available surgical techniques for ASD are used, the posterior rod strain was highest at the lumbosacral junction, and depended on the contour and material of the rods.

In Vitro and In Vivo Comparison of Bone Growth Characteristics in Additive-Manufactured Porous Titanium, Nonporous Titanium, and Porous Tantalum Interbody Cages

Autogenous bone grafts are the gold standard for interbody fusion implant materials; however, they have several disadvantages. Tantalum (Ta) and titanium (Ti) are ideal materials for interbody cages because of their biocompatibility, particularly when they are incorporated into a three-dimensional (3D) porous structure. We conducted an in vitro investigation of the cell attachment and osteogenic markers of self-fabricated uniform porous Ti (20%, 40%, 60%, and 80%), nonporous Ti, and porous Ta cages (n = 6) in each group. Cell attachment, osteogenic markers, and alkaline phosphatase (ALP) were measured. An in vivo study was performed using a pig-posterior-instrumented anterior interbody fusion model to compare the porous Ti (60%), nonporous Ti, and porous Ta interbody cages in 12 pigs. Implant migration and subsidence, determined using plain radiographs, were recorded before surgery, immediately after surgery, and at 1, 3, and 6 months after surgery. Harvested implants were assessed for bone ingrowth and attachment. Relative to the 20% and 40% porous Ti cages, the 60% and 80% cages achieved superior cellular migration into cage pores. Among the cages, osteogenic marker and ALP activity levels were the highest in the 60% porous Ti cage, osteocalcin expression was the highest in the nonporous Ti cage, and the 60% porous Ti cage exhibited the lowest subsidence. In conclusion, the designed porous Ti cage is biocompatible and suitable for lumbar interbody fusion surgery and exhibits faster fusion with less subsidence compared with porous Ta and nonporous Ti cages.

Metal failure and nonunion at L5-S1 after long instrumented fusion distal to pelvis for adult spinal deformity: Anterior versus transforaminal interbody fusion

PURPOSE

Pseudoarthrosis and metal failure at L5-S1 following long fusion surgery for adult spinal deformity (ASD) remain major issues. Few studies report on which anterior column support technique is better in terms of achieving fusion and avoiding metal failures. Our study aimed to evaluate the fusion status and metal failure rate at L5-S1 after anterior lumbar interbody fusion (ALIF) versus transforaminal lumbar interbody fusion (TLIF).

METHODS

The study population included patients aged >50 years who underwent surgery for ASD. Anterior column supports at L5-S1 using ALIF and TLIF were compared with ≥ 2-year follow-up. Fusion status on 2-year computed tomography (CT) scan, metal failure, visual analog scale (VAS), and Oswestry disability index (ODI) were evaluated.

RESULTS

98 patients were included in this study (53 ALIF group and 45 TLIF group). We achieved solid fusion on 2-year CT scans in 88.9% and 69.8% patients in the TLIF and ALIF group, respectively. Metal failure developed in nine (17.0%) and six (13.3%) patients in the ALIF and TLIF group, respectively. The most common failure type was unilateral L5-S1 rod fracture (7 and five patients in the ALIF and TLIF group, respectively). Only one patient with bilateral rod fractures in the ALIF group required revision surgery. There were no differences in the VAS and ODI scores at the last follow-up.

CONCLUSIONS

TLIF showed a better fusion rate than ALIF at L5-S1 after long instrumented fusion for ASD. However, the capacity to restore sagittal parameters was greater in the ALIF group. There were no differences between the groups regarding metal failure rate, revision surgery, or clinical outcomes.

Single position lumbar fusion: a systematic review and meta-analysis

BACKGROUND CONTEXT

Recently, a single position lumbar fusion has been described in which both the anterior or lateral interbody fusion as well as posterior percutaneous pedicle screw fixation are performed in a single position.

PURPOSE

The purpose of this study was to present and analyze the current evidence for single position lumbar fusion.

STUDY DESIGN/SETTING

This is a systematic review and meta-analysis.

PATIENT SAMPLE

Prospective or retrospective studies published in English that assessed outcomes of single position lumbar fusion surgery for patients with lumbar degenerative disease, spondylolisthesis, or radiculopathy were included.

OUTCOME MEASURES

Outcome measures included operative time, estimated blood loss, hospital length of stay, X-Ray exposure time, and postoperative outcomes including leg numbness or pain, leg weakness, lumbar lordosis, and segmental lordosis.

METHODS

This systematic review was performed in accordance with PRISMA guidelines. Two separate meta-analyses were performed. The first compared single position (SP) surgery, both lateral and prone, to dual position or flipped (F) surgery. The second meta-analysis compared lateral single position (LSP) surgery to prone single position (PSP) surgery. Variables were included if (1) they were a mean with a reported standard deviation or (2) if they were a categorical variable. For calculating standard error of the mean, we used sample size, mean, and standard deviation. A random effects model was used. The heterogeneity among studies was assessed with a significance level of <0.05.

RESULTS

Twenty-one articles were included for analysis. Three studies were prospective nonrandomized studies, while 18 were retrospective. Seven articles studied lateral single position only, 10 articles compared lateral single position to traditional repositioning surgery, three articles studied prone single position surgery, and one article compared prone single position surgery to traditional repositioning surgery. A detailed review is provided for all 21 articles. Seventeen studies were included for meta-analysis comparing the SP versus F groups, for a total of 942 patients in the SP group and 254 in the F group. Mean operative time was significantly less for the SP group compared with the F group (SP: 127.5±7.9, F: 188.7±15.5, p<.001). Average hospital length of stay was 2.87±0.3 days in the SP group and 6.63±0.6 days in the F group (p<.001). Complication rates did not significantly differ between groups. Pedicle screws placed in the lateral position had a higher rate of complication as compared with those placed in a prone position (L: 10.2±2%, P: 1.6±1%, p=.015). Seventeen studies were included in the LSP versus PSP analysis, including 13 in the LSP group and four in the PSP group, with a total of 785 patients in the LSP group and 85 patients in the PSP group. Operative time and X-Ray exposure was significantly less in the LSP compared with the PSP group (117.1±5.5 minutes vs. 166.9±21.9 minutes, p<.001; 43.7±15.5 minutes vs. 171.0±25.8 minutes, p<.001). Postoperative segmental lordosis was greater in the prone single position group (p<.001).

CONCLUSIONS

Single position surgery decreases operative times and hospital length of stay, while maintaining similar complication rates and radiographic outcomes. PSP surgery was found to be longer in duration and have increased radiation exposure time compared with LSP, while increasing postoperative segmental lordosis.

Revision Surgery for Adjacent Segment Degeneration After Fusion for Lumbar Spondylolisthesis: Is there a Correlation with Roussouly Type?

STUDY DESIGN

Retrospective study.

OBJECTIVE

The aim of this study was to investigate whether there is an association between revision surgery rates for adjacent segment degeneration (ASD) and Roussouly type after L4-5 transforaminal lumbar interbody fusion (TLIF) for spondylolisthesis.

SUMMARY OF BACKGROUND DATA

Revision surgery for ASD is known to occur after spinal fusion; however, it is unclear whether rates of ASD are associated with certain Roussouly types.

METHODS

Patients who underwent L4-5 TLIF for spondylolisthesis at the University of California San Francisco from January 2006 to December 2016 with minimum 2-year follow-up were retrospectively analyzed by Roussouly type. Revision surgery for ASD was noted and correlated by Roussouly type. Spinopelvic parameters were also measured for correlation. A value of P < 0.05 was significant.

RESULTS

There were 174 patients who met inclusion criteria, (59 males and 115 females). The average age was 62.3 (25-80) years. A total of 132 patients had grade I spondylolisthesis, and 42 had grade II. Mean follow-up was 45.2 months (24-497). A total of 22 patients (12.6%) underwent revision surgery for ASD after L4-5 TLIF. When classified by Roussouly type, revision surgery rates for ASD were: 1, 14.3%; 2, 22.6%; 3, 4.9%; and 4, 15.6% (P = 0.013). Type 3 spines with normal PI-LL (8.85° ± 6.83°) had the lowest revision surgery rate (4.9%), and type 2 spines with PI-LL mismatch (11.06° ± 8.81°) had the highest revision surgery rate (22.6%), a four-fold difference (P = 0.013). The PI-LL mismatch did not change significantly in each type postoperatively (P > 0.05).

CONCLUSION

We found that there may be a correlation between Roussouly type and revision surgery for ASD after L4-5 TLIF for spondylolisthesis, with type 2 spines having the highest rate. Spinopelvic parameters may also correlate with revision surgery for ASD after L4-5 TLIF.Level of Evidence: 4.

Comparison of Incidence of Adjacent Segment Pathology between Anterior Lumbar Interbody Fusion and Transforaminal Lumbar Interbody Fusion Treatments for Lumbosacral Junction

This research compared the incidence of adjacent segment pathology (ASP) between anterior interbody lumbar fusion (ALIF) treatment and transforaminal lumbar interbody fusion (TLIF) treatment. Seventy patients were included in this retrospective study: 30 patients received ALIF treatment, and 40 patients received TLIF treatment at a single medical center between 2011 and 2020 with a follow-up of at least 12 months. The outcomes were radiographic adjacent segment pathology (RASP) and clinical adjacent segment pathology (CASP). The mean follow-up period was 42.10 ± 22.61 months in the ALIF group and 56.20 ± 29.91 months in the TLIF group. Following single-level lumbosacral fusion, ALIF is superior to TLIF in maintaining lumbar lordosis, whereas the risk of adjacent instability in the ALIF group is significantly higher. Regarding ASP, the incidence of overall RASP and CASP did not differ significantly between ALIF and TLIF groups.

Pseudarthrosis and Rod Fracture Rates After Transforaminal Lumbar Interbody Fusion at the Caudal Levels of Long Constructs for Adult Spinal Deformity Surgery

BACKGROUND

Interbody fusion at the caudal levels of long constructs for adult spinal deformity (ASD) surgery is used to promote fusion and secure a solid foundation for maintenance of deformity correction. We sought to evaluate long-term pseudarthrosis, rod fracture, and revision rates for TLIF performed at the base of a long construct for ASD.

METHODS

We reviewed 316 patients who underwent TLIF as a component of ASD surgery for medical comorbidities, surgical characteristics, and rate of unplanned reoperation for pseudarthrosis or instrumentation failure at the TLIF level. Fusion grading was assessed after revision surgery for pseudarthrosis at the TLIF level.

RESULTS

Rate of pseudarthrosis at the TLIF level was 9.8% (31/316), and rate of rod fractures was 7.9% (25/316). The rate of revision surgery at the TLIF level was 8.9% (28/316), and surgery was performed at a mean of 20.4 ± 16 months from the index procedure. Current smoking status (odds ratio 3.34, P = 0.037) was predictive of pseudarthrosis at the TLIF site. At a mean follow-up of 43 ± 12 months after revision surgery, all patients had achieved bony union at the TLIF site.

CONCLUSIONS

At 3-year follow-up, the rate of pseudarthrosis after TLIF performed at the base of a long fusion for ASD was 9.8%, and the rate of revision surgery to address pseudarthrosis and/or rod fracture was 8.9%. All patients were successfully treated with revision interbody fusion or posterior augmentation of the fusion mass, without need for further revision procedures at the TLIF level.

Improvement of coronal alignment in fractional low lumbar curves with the use of anterior interbody devices

STUDY DESIGN

Retrospective chart review.

OBJECTIVES

To determine if the addition of an anterior lumbar interbody fusion (ALIF) improves the fractional curve in adult spinal deformity correction when compared to posterior surgery alone. ALIF is commonly advocated to improve lordosis and fusion in adult deformity surgery. Improved fractional curve correction may help level the pelvis and minimize proximal malalignment.

METHODS

Patients undergoing thoracolumbar fusion to the pelvis with S2AI screws for deformity were identified and stratified into patients who had an ALIF as part of their deformity correction procedure (ALIF + PSF), and those who had a posterior approach alone. The posterior approach (PSF) includes patients who had a posterolateral fusion with or without a transforaminal lumbar interbody fusion (TLIF). Radiographic parameters measured included pre-op and post-op fractional coronal curve Cobb angle, lumbar lordosis, pelvic tilt, pelvic incidence and sacral slope, major Cobb angle, coronal and sagittal SVA.

RESULTS

There were 31 cases in the ALIF + PSF group and 28 in the PSF group. Baseline demographic characteristics of the two groups were similar. Mean pre-op fractional coronal Cobb (18.3° vs 13.4°, p = 0.027) was larger in the ALIF + PSF group, whereas lumbar lordosis (31.0° vs 33.6°, p = 0.487) and pelvic parameters were similar between the two groups. Post-op lumbar lordosis was similar (48.2° vs 43.0°, p = 0.092). Greater fractional coronal curve correction was achieved in the ALIF + PSF group (67%) compared to the PSF group (36%) with a smaller post-op fractional coronal curve in the ALIF + PSF group (6.1°) compared to the PSF group (8.6°, p = 0.053).

CONCLUSION

There is a greater correction of the fractional curve in the ALIF + PSF group compared with the PSF group. While this may not be the primary indication for ALIF, it is a benefit which may facilitate overall deformity correction and leveling of the pelvis.

Multicenter assessment of outcomes and complications associated with transforaminal versus anterior lumbar interbody fusion for fractional curve correction

OBJECTIVE

Few studies have compared fractional curve correction after long fusion between transforaminal lumbar interbody fusion (TLIF) and anterior lumbar interbody fusion (ALIF) for adult symptomatic thoracolumbar/lumbar scoliosis (ASLS). The objective of this study was to compare fractional correction, health-related quality of life (HRQL), and complications associated with L4-S1 TLIF versus those of ALIF as an operative treatment of ASLS.

METHODS

The authors retrospectively analyzed a prospective multicenter adult spinal deformity database. Inclusion required a fractional curve ≥ 10°, a thoracolumbar/lumbar curve ≥ 30°, index TLIF or ALIF performed at L4-5 and/or L5-S1, and a minimum 2-year follow-up. TLIF and ALIF patients were propensity matched according to the number and type of interbody fusion at L4-S1.

RESULTS

Of 135 potentially eligible consecutive patients, 106 (78.5%) achieved the minimum 2-year follow-up (mean ± SD age 60.6 ± 9.3 years, 85% women, 44.3% underwent TLIF, and 55.7% underwent ALIF). Index operations had mean ± SD 12.2 ± 3.6 posterior levels, 86.6% of patients underwent iliac fixation, 67.0% underwent TLIF/ALIF at L4-5, and 84.0% underwent TLIF/ALIF at L5-S1. Compared with TLIF patients, ALIF patients had greater cage height (10.9 ± 2.1 mm for TLIF patients vs 14.5 ± 3.0 mm for ALIF patients, p = 0.001) and lordosis (6.3° ± 1.6° for TLIF patients vs 17.0° ± 9.9° for ALIF patients, p = 0.001) and longer operative duration (6.7 ± 1.5 hours for TLIF patients vs 8.9 ± 2.5 hours for ALIF patients, p < 0.001). In all patients, final alignment improved significantly in terms of the fractional curve (20.2° ± 7.0° to 6.9° ± 5.2°), maximum coronal Cobb angle (55.0° ± 14.8° to 23.9° ± 14.3°), C7 sagittal vertical axis (5.1 ± 6.2 cm to 2.3 ± 5.4 cm), pelvic tilt (24.6° ± 8.1° to 22.7° ± 9.5°), and lumbar lordosis (32.3° ± 18.8° to 51.4° ± 14.1°) (all p < 0.05). Matched analysis demonstrated comparable fractional correction (-13.6° ± 6.7° for TLIF patients vs -13.6° ± 8.1° for ALIF patients, p = 0.982). In all patients, final HRQL improved significantly in terms of Oswestry Disability Index (ODI) score (42.4 ± 16.3 to 24.2 ± 19.9), physical component summary (PCS) score of the 36-item Short-Form Health Survey (32.6 ± 9.3 to 41.3 ± 11.7), and Scoliosis Research Society-22r score (2.9 ± 0.6 to 3.7 ± 0.7) (all p < 0.05). Matched analysis demonstrated worse ODI (30.9 ± 21.1 for TLIF patients vs 17.9 ± 17.1 for ALIF patients, p = 0.017) and PCS (38.3 ± 12.0 for TLIF patients vs 45.3 ± 10.1 for ALIF patients, p = 0.020) scores for TLIF patients at the last follow-up (despite no differences in these parameters at baseline). The rates of total complications were similar (76.6% for TLIF patients vs 71.2% for ALIF patients, p = 0.530), but significantly more TLIF patients had rod fracture (28.6% of TLIF patients vs 7.1% of ALIF patients, p = 0.036). Multiple regression analysis demonstrated that a 1-mm increase in L4-5 TLIF cage height led to a 2.2° reduction in L4 coronal tilt (p = 0.011), and a 1° increase in L5-S1 ALIF cage lordosis led to a 0.4° increase in L5-S1 segmental lordosis (p = 0.045).

CONCLUSIONS

Operative treatment of ASLS with L4-S1 TLIF versus ALIF demonstrated comparable mean fractional curve correction (66.7% vs 64.8%), despite use of significantly larger, more lordotic ALIF cages. TLIF cage height had a significant impact on leveling L4 coronal tilt, whereas ALIF cage lordosis had a significant impact on restoration of lumbosacral lordosis. The advantages of TLIF may include reduced operative duration and hospitalization; however, associated HRQL was inferior and more rod fractures were detected in the TLIF patients included in this study.

Does Interbody Support at L5-S1 Matter in Long Fusions to the Pelvis?: A 5-year Analysis

STUDY DESIGN

Retrospective review of prospectively collected data.

OBJECTIVE

To determine if the addition of L5-S1 interbody support in long fusion deformity constructs is associated with superior long-term clinical and radiographic outcomes. To compare the 5-year clinical and radiographic outcomes and complications between long fusion constructs with L5-S1 interbody support versus posterolateral fusion (PLF) alone.

SUMMARY OF BACKGROUND DATA

Cadaveric biomechanical studies have suggested that an interbody fusion at L5-S1 is beneficial in long fusion constructs with sacropelvic fixation. However, there is limited data reflecting the superiority of interbody support augmentation in optimizing arthrodesis and deformity correction relative to PLF alone.

METHODS

Eighty-eight consecutive adults with spinal deformity who underwent at minimum T11-pelvis posterior pedicle screw instrumentation with 5-year follow-up were included. Two cohorts were compared based on technique used at the lumbosacral junction (L5-S1): (A) no interbody (PLF; n = 23), or (B) interbody support at L5-S1 (IB; n = 65). Radiographic measurements and clinical outcome measures were compared at multiple time points. Complications were recorded and compared.

RESULTS

No differences in baseline patient characteristics between cohorts. One nonunion occurred at L5-S1 in the PLF group (P = 0.091). Initial postop sagittal alignment was better in the IB group (PLF: 6.46 cm, IB: 2.48 cm, P = 0.007); however, this was not maintained over long-term follow-up. No significant differences in proximal junctional kyphosis (PLF: 7/23, IB: 9/65, P = 0.076). Proximal junctional failure was more frequent in the PLF group (PLF: 6/23, IB: 6/65, P = 0.043). No significant differences in complications were found. Both cohorts had improvement from baseline pain and functional scores.

CONCLUSION

There is no absolute long-term advantage for lumbar interbody support in adult spinal deformity patients undergoing spinal arthrodesis to the pelvis.Level of Evidence: 3.

Does transforaminal lumbar interbody fusion induce lordosis or kyphosis? Radiographic evaluation with a minimum 2-year follow-up

OBJECTIVE

Conflicting reports exist about whether transforaminal lumbar interbody fusion (TLIF) induces lordosis or kyphosis, ranging from decreasing lordosis by 3.71° to increasing it by 18.8°. In this study, the authors' aim was to identify factors that result in kyphosis or lordosis after TLIF.

METHODS

A single-center, retrospective study of open TLIF without osteotomy for spondylolisthesis with a minimum 2-year follow-up was undertaken. Preoperative and postoperative clinical and radiographic parameters and cage specifics were collected. TLIFs were considered to be "lordosing" if postoperative induction of lordosis was > 0° and "kyphosing" if postoperative induction of lordosis was ≤ 0°.

RESULTS

A total of 137 patients with an average follow-up of 52.5 months (range 24-130 months) were included. The overall postoperative disc angle (DA) and segmental lordosis (SL) increased by 1.96° and 1.88° (p = 0.003 and p = 0.038), respectively, whereas overall lumbar lordosis remained unchanged (p = 0.133). Seventy-nine patients had lordosing TLIFs with a mean SL increase of 5.72° ± 3.97°, and 58 patients had kyphosing TLIFs with a mean decrease of 3.02° ± 2.98°. Multivariate analysis showed that a lower preoperative DA, lower preoperative SL, and anterior cage placement were correlated with the greatest increase in postoperative SL (p = 0.040, p < 0.001, and p = 0.035, respectively). There was no difference in demographics, cage type or height, or spinopelvic parameters between the groups (p > 0.05). Linear regression showed that the preoperative DA and SL correlated with SL after TLIF (R2 = 0.198, p < 0.001; and R2 = 0.2931, p < 0.001, respectively).

CONCLUSIONS

Whether a TLIF induces kyphosis or lordosis depends on the preoperative DA, preoperative SL, and cage position. Less-lordotic segments became more lordotic postoperatively, and highly lordotic segments may lose lordosis after TLIF. Cages placed more anteriorly were associated with more lordosis.

Clinical and Radiographic Comparison Between Open Versus Minimally Invasive Transforaminal Lumbar Interbody Fusion With Bilateral Facetectomies

STUDY DESIGN

Age- and sex-matched cohort study.

OBJECTIVES

To compare outcomes after open versus minimally invasive transforaminal lumbar interbody fusion (MIS-TLIF) with bilateral facetectomies.

METHODS

We retrospectively compared patients who underwent single- or 2-level MIS-TLIF with an age- and sex-matched open-TLIF cohort. Surgical data was collected for operative time, estimated blood loss (EBL), and drain use. Clinical outcomes included the Visual Analog Scale (VAS), Oswestry Disability Index (ODI), length of stay (LOS), complications, and reoperations. Lumbar radiographs were measured for changes in global lumbar lordosis (LL) and segmental lordosis (SL).

RESULTS

Between 2016 and 2020, 38 MIS-TLIF patients were compared with 38 open-TLIF patients. No subfascial drain was used in the MIS-TLIF group (P < .001). The MIS-TLIF group had longer operative time (310.8 vs 276.5 minutes; P = .046) but less EBL (282.4 vs 420.8 mL; P = .007). LOS (P = .15), complication rates (P = .50), and revision rates (P = .17) were equivalent. VAS and ODI improved but did not differ between groups. In the open-TLIF group, LL and SL were restored or improved in 81.6% and 86.9% of cases, respectively. In the MIS-TLIF group, LL and SL were restored or improved in 86.8% and 97.4% of cases, respectively. There were no differences in changes in LL and SL between groups.

CONCLUSIONS

Compared with the age- and sex-matched open-TLIF cohort, patients undergoing MIS-TLIF had reduced EBL and subfascial drain use but increased operative time. There were no differences in complications, reoperations, or LOS. Both groups demonstrated improvement in VAS and ODI. MIS-TLIF with bilateral facetectomies provided equivalent improvements in global and segmental LL.

A retrospective comparison of radiographic and clinical outcomes in single-level degenerative lumbar disease undergoing anterior versus transforaminal lumbar interbody fusion

Background

Single-level lumbar degenerative disc disease (DDD) remains a significant cause of morbidity in adulthood. Anterior lumbar interbody fusion (ALIF) and Transforaminal lumbar interbody fusion (TLIF) are surgical techniques developed to treat this condition. With limited studies on intermediate term outcomes in a single cohort, we compare radiographic and clinical outcomes in patients undergoing ALIF and TLIF.

Methods

A retrospective chart review was performed on 164 patients (111 TLIF; 53 ALIF) over a 60-month period. X-ray radiographs obtained pre-operatively, prior to discharge, and at one year were utilized for radiographic assessment. Segmental lordosis, lumbar lordosis and HRQOL scores were measured preoperatively and at one-year timepoints.

Results

Changes in lumbar lordosis and segmental lordosis were significantly greater after ALIF (4.6° vs. -0.6°, P=0.05; 4.7° vs. -0.7°, P<0.05) at one year (mean time, 366±20 days). At one year or greater, there was a greater reduction in mean VAS-leg score in TLIF patients (3.4 vs. 0.6, P<0.05) and ODI score (16.2 vs. 5.4, P<0.05). Similar outcomes were seen for VAS-back, SF-12 Physical Health, and SRS-30 Function/Activity. SF-12 Mental Health scores were found to be lower in patients undergoing TLIF (-3.5 vs. 2.7, P<0.05).

Conclusions

ALIF demonstrated a superior method of increasing lumbar and segmental lordosis. TLIF was utilized more in patients with higher pre-operative VAS-leg pain scores and therefore, showed a greater magnitude of VAS-leg pain improvement. TLIF also demonstrated a greater improvement in ODI scores despite similar baseline scores, suggesting a possible enhanced functional outcome.

Three- and 4-Level Lumbar Arthrodesis Using Adjunctive Pulsed Electromagnetic Field Stimulation: A Multicenter Retrospective Evaluation of Fusion Rates and a Review of the Literature

BACKGROUND

The incidence of 3- and 4-level lumbar arthrodesis is rising due to an aging population, and fusion rates affect clinical success in this population. Pulsed electromagnetic field (PEMF) stimulation is used as an adjunct to increase fusion rates following multilevel arthrodesis. The purpose of the study was to evaluate the fusion rates for subjects who underwent 3- and 4-level lumbar interbody arthrodesis following PEMF treatment.

METHODS

In this retrospective, multicenter study, patient charts that listed 3- or 4-level lumbar arthrodesis with adjunctive use of a PEMF device were evaluated. Inclusion criteria included patients who were diagnosed with lumbar degenerative disease, spinal stenosis, and/or spondylolisthesis (grade 1 or 2). A radiographic evaluation of fusion status was performed at 12 months by the treating physicians. Fusion rates were stratified by graft material, surgical interbody approach, and certain clinical risk factors for pseudoarthrosis.

RESULTS

A total of 55 patients were identified who had a 12-month follow-up. The radiographic fusion rate was 92.7% (51 patients) at 12 months. There were no significant differences in fusion rates for patients treated with allograft or autograft, for patients with different interbody approaches, or for those with or without certain clinical risk factors.

CONCLUSIONS

With modern fusion techniques and PEMF, the overall fusion rate was high following 3- and 4-level lumbar arthrodesis.

LEVEL OF EVIDENCE

4.

CLINICAL RELEVANCE

PEMF may be a useful adjunct for treatment of patients with surgical risk factors, such as multilevel arthrodesis, and clinical risk factors.

The minimally invasive interbody selection algorithm for spinal deformity

OBJECTIVE

Minimally invasive surgery (MIS) for spinal deformity uses interbody techniques for correction, indirect decompression, and arthrodesis. Selection criteria for choosing a particular interbody approach are lacking. The authors created the minimally invasive interbody selection algorithm (MIISA) to provide a framework for rational decision-making in MIS for deformity.

METHODS

A retrospective data set of circumferential MIS (cMIS) for adult spinal deformity (ASD) collected over a 5-year period was analyzed by level in the lumbar spine to identify surgeon preferences and evaluate segmental lordosis outcomes. These data were used to inform a Delphi session of minimally invasive deformity surgeons from which the algorithm was created. The algorithm leads to 1 of 4 interbody approaches: anterior lumbar interbody fusion (ALIF), anterior column release (ACR), lateral lumbar interbody fusion (LLIF), and transforaminal lumbar interbody fusion (TLIF). Preoperative and 2-year postoperative radiographic parameters and clinical outcomes were compared.

RESULTS

Eleven surgeons completed 100 cMISs for ASD with 338 interbody devices, with a minimum 2-year follow-up. The type of interbody approach used at each level from L1 to S1 was recorded. The MIISA was then created with substantial agreement. The surgeons generally preferred LLIF for L1-2 (91.7%), L2-3 (85.2%), and L3-4 (80.7%). ACR was most commonly performed at L3-4 (8.4%) and L2-3 (6.2%). At L4-5, LLIF (69.5%), TLIF (15.9%), and ALIF (9.8%) were most commonly utilized. TLIF and ALIF were the most selected approaches at L5-S1 (61.4% and 38.6%, respectively). Segmental lordosis at each level varied based on the approach, with greater increases reported using ALIF, especially at L4-5 (9.2°) and L5-S1 (5.3°). A substantial increase in lordosis was achieved with ACR at L2-3 (10.9°) and L3-4 (10.4°). Lateral interbody arthrodesis without the use of an ACR did not generally result in significant lordosis restoration. There were statistically significant improvements in lumbar lordosis (LL), pelvic incidence-LL mismatch, coronal Cobb angle, and Oswestry Disability Index at the 2-year follow-up.

CONCLUSIONS

The use of the MIISA provides consistent guidance for surgeons who plan to perform MIS for deformity. For L1-4, the surgeons preferred lateral approaches to TLIF and reserved ACR for patients who needed the greatest increase in segmental lordosis. For L4-5, the surgeons' order of preference was LLIF, TLIF, and ALIF, but TLIF failed to demonstrate any significant lordosis restoration. At L5-S1, the surgical team typically preferred an ALIF when segmental lordosis was desired and preferred a TLIF if preoperative segmental lordosis was adequate.

Preoperative lordosis in L4/5 predicts segmental lordosis correction achievable by transforaminal lumbar interbody fusion

PURPOSE

The mean potential of lordosis restoration by transforaminal lumbar interbody fusion (TLIF) is supposed to be low in general. In contrast, clinical experience shows a wide range of segmental lordosis correction. In this study, the predictability of lordosis correction should be investigated.

METHODS

Prospectively collected register data were analyzed retrospectively. One hundred twenty-one consecutive patients (2014-2016) operated with single-level TLIF L4/5 (10°-lordotic cage). Segmental lordosis (L4/5) and overall lordosis (L1-S1) were measured on lumbar X-rays: preoperatively (pre), after 3-5 days (post), at least 24 months postoperatively (2yFU). Outcome and satisfaction of patients were assessed. Parameters were statistically compared by students t-tests (a = 0.05). In addition, predictors of correction were analyzed.

RESULTS

Age was 60.7 years, rate of 2yFU 41.3% (n = 50). Lordosis correction L4/5 was statistically significant with (post-pre) 4.9 ± 5.7° (p < 0.01), but not significant for L1-S1 (post-pre) 1.6 ± 8.0° (p = 0.3). A strong-moderate correlation of lordosis L4/5 (pre) and lordosis correction L4/5 (post-pre) was shown (r =  - 0.6, p < 0,01). In a rising range of preoperative lordosis L4/5 from 15-30° the likelihood of lordosis loss increased. In 2yFU correction, L4/5 was significant with (post-pre) 5.4 ± 5.4° (p < 0.01), no significant long-term change (2yFU-postop)  - 1.5 ± 4.9° (p = 0.2). No correlation (r =  - 0.1) of correction and ODI. VAS-B improved by means of 2.9, VAS-L by 2.5, ODI by 19.1% (pre vs. 2yFU), each statistically significant (p < 0.01).

CONCLUSION

Significant segmental relordosation can be performed by TLIF L4/5. The potential of correction strongly correlates with preoperative lordosis. Therefore, TLIF technique should be considered carefully in cases with a preoperative segmental lordosis of more than 15° and additional need of lordosation.

Comparison of Different Approaches in Lumbosacral Spinal Fusion Surgery: A Systematic Review and Meta-Analysis

We aimed to systematically review the literature to analyze the differences in posterior lumbar interbody fusion (PLIF), anterior lumbar interbody fusion (ALIF), and transforaminal lumbar interbody fusion (TLIF), focusing on the complications, risk factors, and fusion rate of each approach. Spinal fusion surgery is a well-established surgical procedure for a variety of indications, and different approaches developed. The various approaches and their advantages, as well as approach-related pathology and complications, are well investigated in spinal surgery. Focusing only on lumbosacral fusion, the comparative studies of different approaches remain fewer in numbers. We systematically reviewed the literature on the complications associated with lumbosacral interbody fusion. Only the PLIF, ALIF, or TLIF approaches and studies published within the last decade (2007–2017) were included. The exclusion criteria in this study were oblique lumbar interbody fusion, extreme lateral interbody fusion, more than one procedure per patient, and reported patient numbers less than 10. The outcome variables were indications, fusion rates, operation time, perioperative complications, and clinical outcome by means of Visual Analog Scale, Oswestry Disability Index, and Japanese Orthopaedic Association score. Five prospective, 17 retrospective, and two comparative studies that investigated the lumbosacral region were included. Mean fusion rates were 91,4%. ALIF showed a higher operation time, while PLIF resulted in greater blood loss. In all approaches, significant improvements in the clinical outcome were achieved, with ALIF showing slightly better results. Regarding complications, the ALIF technique showed the highest complication rates. Lumbosacral fusion surgery is a treatment to provide good results either through an approach for various indications as causes of lower back pain. For each surgical approach, advantages can be depicted. However, perioperative complications and risk factors are numerous and vary with ALIF, PLIF, and TLIF procedures, as well as with fusion rates.

The lumbar autonomic nerves in males: a few anatomical insights into anterior lumbar interbody fusion

BACKGROUND CONTEXT

Lumbar autonomic nerve injury is an underappreciated complication of anterior lumbar spinal surgery. A detailed description of lumbar autonomic nerve anatomy would be helpful for surgeons to minimize the risk of this complication.

PURPOSE

This study was designed to investigate the anatomical characteristics of lumbar autonomic nerves and provide a better understanding of these nerves for anterior lumbar spinal surgery.

STUDY DESIGN

A dissection-based study of 10 embalmed male cadavers.

METHODS

The lumbar autonomic nerves from 10 embalmed male cadavers were dissected in this study. The position of the lumbar sympathetic trunks was recorded. Distance between the initial sites of the lumbar splanchnic nerves (LSNs) and the corresponding lumbar vertebral inferior endplate, distance between the ipsilateral and adjacent LSNs, angles formed by the LSNs and the vertical axis were measured. This study has been supported by grants from Science and Technology Planning Project of Guangdong Province (CN) (Grant No. 2017B020210010) without potential conflict of interest-associated biases in the text of the paper.

RESULTS

In this study, a total of 72 LSNs were identified in the 10 human cadavers. On average, the investigation found that the initial sites of the first, second, third, and fourth LSNs were 9 mm distal, 5 mm distal, 9 mm proximal, and 9 mm distal to the inferior endplates of the L1, L2, L3, and L4 vertebrae, respectively, with variations from 6 to 11 mm for each nerve among specimens. There was no significant difference in the angle between each lumbar splanchnic nerve and the vertical axis (H=2.461, p=.482), with an angle of approximately 50°±6°. The distance between the first and the second LSNs, the second and the third LSNs, or the third and the fourth LSNs were 24±6 mm, 22±8 mm, and 55±11 mm, respectively. The bilateral lumbar sympathetic trunks (N=57, 95%) were more likely to be located in the first third of the sagittal plane at the level of the L2/3, L3/4, and L4/5 intervertebral discs.

CONCLUSIONS

The study found the same number and parallel courses of LSNs on each side, and on both the left and right side, the distance between the third and the fourth LSNs was much larger than the distance between the other two adjacent LSNs. The initial sites of 80.6% (n=58) of LSNs were superior to the inferior endplate of the L3 vertebra. Improved knowledge of lumbar autonomic nerve anatomy may be of great significance in reducing complications and improving surgical safety.

The impact of increasing interbody fusion levels at the fractional curve on lordosis, curve correction, and complications in adult patients with scoliosis

OBJECTIVE

Radiculopathy from the fractional curve, usually from L3 to S1, can create severe disability. However, treatment methods of the curve vary. The authors evaluated the effect of adding more levels of interbody fusion during treatment of the fractional curve.

METHODS

A single-institution retrospective review of adult patients treated for scoliosis between 2006 and 2016 was performed. Inclusion criteria were as follows: fractional curves from L3 to S1 > 10°, ipsilateral radicular symptoms concordant on the fractional curve concavity side, patients who underwent at least 1 interbody fusion at the level of the fractional curve, and a minimum 1-year follow-up. Primary outcomes included changes in fractional curve correction, lumbar lordosis change, pelvic incidence - lumbar lordosis mismatch change, scoliosis major curve correction, and rates of revision surgery and postoperative complications. Secondary analysis compared the same outcomes among patients undergoing posterior, anterior, and lateral approaches for their interbody fusion.

RESULTS

A total of 78 patients were included. There were no significant differences in age, sex, BMI, prior surgery, fractional curve degree, pelvic tilt, pelvic incidence, pelvic incidence - lumbar lordosis mismatch, sagittal vertical axis, coronal balance, scoliotic curve magnitude, proportion of patients undergoing an osteotomy, or average number of levels fused among the groups. The mean follow-up was 35.8 months (range 12-150 months). Patients undergoing more levels of interbody fusion had more fractional curve correction (7.4° vs 12.3° vs 12.1° for 1, 2, and 3 levels; p = 0.009); greater increase in lumbar lordosis (-1.8° vs 6.2° vs 13.7°, p = 0.003); and more scoliosis major curve correction (13.0° vs 13.7° vs 24.4°, p = 0.01). There were no statistically significant differences among the groups with regard to postoperative complications (overall rate 47.4%, p = 0.85) or need for revision surgery (overall rate 30.7%, p = 0.25). In the secondary analysis, patients undergoing anterior lumbar interbody fusion (ALIF) had a greater increase in lumbar lordosis (9.1° vs -0.87° for ALIF vs transforaminal lumbar interbody fusion [TLIF], p = 0.028), but also higher revision surgery rates unrelated to adjacent-segment pathology (25% vs 4.3%, p = 0.046). Higher ALIF revision surgery rates were driven by rod fracture in the majority (55%) of cases.

CONCLUSIONS

More levels of interbody fusion resulted in increased lordosis, scoliosis curve correction, and fractional curve correction. However, additional levels of interbody fusion up to 3 levels did not result in more postoperative complications or morbidity. ALIF resulted in a greater lumbar lordosis increase than TLIF, but ALIF had higher revision surgery rates.

Supine anterior lumbar interbody fusion versus lateral position oblique lumbar interbody fusion at L5-S1: A comparison of two approaches to the lumbosacral junction

INTRODUCTION

At L5-S1, anterior access can be performed with a supine anterior lumbar interbody fusion (ALIF) or lateral position oblique lumbar interbody fusion (LOLIF). We compared clinical and radiographic features of both approaches.

METHODS

A retrospective study of L5-S1 ALIF and LOLIF patients (2013-2018) by 3 spine surgeons and a vascular surgeon at our hospital was performed. Inclusion criteria were patients undergoing L5-S1 anterior surgery only without other anterior or lateral fusion levels, and data collected were patient demographics, cage parameters, perioperative variables, and radiographic parameters. 58 patients were included (33 ALIF and 25 LOLIF).

RESULTS

The average surgical time was 211.94 min for ALIF and 154.86 min for LOLIF (p < 0.001). The average blood loss was 214 ml for ALIF and 74 ml for LOLIF (p < 0.001). The average number of days to solid food was 2.55 for ALIF and 0.8 for LOLIF (p < 0.001). The average anterior L5-S1 disc height increase was 8.52 mm for ALIF and 5.02 mm LOLIF (p = 0.018), and the average posterior L5-S1 disc height increase was 3.34 mm for ALIF and 1.30 mm for LOLIF (p = 0.034). The average L5-S1 segmental lordosis increase was 6.82 degrees for ALIF and 7.63 degrees for LOLIF (p = 0.638).

CONCLUSION

The LOLIF is a feasible option for L5-S1 anterior access compared to ALIF. However, supine ALIF afforded larger cages to be placed, resulting in greater postoperative disc height. There did not appear to be a significant difference in postoperative L5-S1 segmental lordosis between the two approaches.

Clinical and Radiographic Outcomes After Minimally Invasive Transforaminal Lumbar Interbody Fusion-Early Experience Using a Biplanar Expandable Cage for Lumbar Spondylolisthesis

BACKGROUND

Minimally invasive transforaminal lumbar interbody fusion (MIS TLIF) is a surgical technique frequently used to treat symptomatic lumbar spondylolisthesis. We aim to investigate the safety and efficacy of using a biplanar expandable cage in the treatment of symptomatic lumbar spondylolisthesis using a MIS TLIF approach.

METHODS

A retrospective review of patient records was performed on patients who underwent MIS TLIF for symptomatic lumbar spondylolisthesis using the FlareHawk cage over a 12-month period. Patient demographics, as well as preoperative and postoperative clinical and radiographic outcome measures were recorded and analyzed.

RESULTS

A total of 13 consecutive patients underwent MIS TLIF for symptomatic spondylolisthesis during the study period. The mean age was 60.2 ± 13.9 years, and 61.5% were female. The mean preoperative and postoperative slippage was 7.0 ± 3.0 mm and 1.0 ± 1.9 mm, respectively. The preoperative mean segmental lordosis was 5.1° ± 6.0°, mean anterior, posterior disc, and foraminal height were 9.1 ± 3.9 mm, 5.7 ± 1.5 mm, and 11.0 ± 2.0 mm, respectively. The postoperative mean segmental lordosis was 6.8° ± 4.7°, and mean anterior, posterior disc, and foraminal height were 11.4 ± 2.2 mm, 7.8 ± 1.0 mm, and 12.3 ± 1.3 mm. There was improvement in all radiographic parameters postoperatively. The mean Visual Analog Scale (VAS) back pain, VAS leg pain improved from 7.0 ± 2.9 and 5.1 ± 3.0 preoperatively to 3.1 ± 2.9 and 1.1 ± 1.7 at the latest clinic follow-up visit, respectively (P = .0081). The mean EuroQol-Five Dimensions (EQ5D) score improved from 0.37 ± 1.7 to 0.66 ± 0.23 after surgery. There was no subsidence, endplate violation, cage migration, or other implant-related complications. No patient required reoperation.

CONCLUSIONS

The biplanar expandable cage is both safe and efficacious in treating symptomatic lumbar spondylolisthesis using the MIS TLIF approach. Spine surgeons should be familiar with the biplanar expandable cage technology and keep it in their armamentarium in surgical treatment of lumbar spondylolisthesis.

LEVEL OF EVIDENCE

4.

ALIF in the correction of spinal sagittal misalignment. A systematic review of literature

PURPOSE

We aim at analysing the impact of anterior lumbar interbody fusion (ALIF) in restoring the main spinopelvic parameters, along with its potentials and limitations in correcting sagittal imbalance.

MATERIALS AND METHODS

The 2009 PRISMA flow chart was used to systematically review the literature; 27 papers were eventually selected. The following spinopelvic parameters were observed: pelvic tilt (PT), sacral slope (SS), lumbar lordosis (LL), segmental lumbar lordosis (LLseg) and sagittal vertical axis (SVA). Papers reporting on hyperlordotic cages (HLC) were analysed separately. The indirect decompression potential of ALIF was also assessed. The clinical outcome was obtained by collecting visual analogue scale (VAS) for back and leg pain and Oswestry Disability Index (ODI) scores. Global fusion rate and main complications were collected.

RESULTS

PT, SS, LL, LLseg and SVA spinopelvic parameters all improved postoperatively by - 4.3 ± 5.2°, 3.9 ± 4.5°, 10.6 ± 12.5°, 6.7 ± 3.5° and 51.1 ± 44.8 mm, respectively. HLC were statistically more effective in restoring LL and LLseg (p < 0.05). Postoperative disc height, anterior disc height, posterior disc height and foraminal height, respectively, increased by 58.5%, 87.2%, 80.9% and 18.1%. Postoperative improvements were observed in VAS back and leg and ODI scores (p < 0.05). The global fusion rate was 94.5 ± 5.5%; the overall complication rate was 13%.

CONCLUSION

When managing sagittal imbalance, ALIF can be considered as a valid technique to achieve the correct spinopelvic parameters based on preoperative planning. This technique permits to obtain an optimal LL distribution and a solid anterior column support, with lower complications and higher fusion rates when compared to posterior osteotomies.

Assessment of Great Vessels for Anterior Access of L5/S1 Using Patient Positioning

STUDY DESIGN

This was a prospective cross-sectional study.

PURPOSE

The aim was to describe the effect of patient positioning, from supine to lateral decubitus position, on the width of the L5/S1 anterior disk space defined by the great vessels.

OVERVIEW OF LITERATURE

The application of the lateral decubitus position interbody fusion has been rapidly increasing; however, there are concerns regarding the access to the lumbosacral region due to the great vessels, which necessitates further morphometric data.

METHODS

A total of 20 consecutive live patients awaiting lumbar surgery were subjected to two magnetic resonance imaging scans on the same day in both supine and lateral decubitus positions at a single center to investigate the anterior L5/S1 disk space.

RESULTS

The bare anterior L5/S1 disk window was present in all patients of this study population, and the mean width was 27 mm in the supine and 22 mm in the lateral decubitus position, with a mean reduction of 5.2 mm between the positions. The oblique corridor angle was measured at a mean of 33°.

CONCLUSIONS

The bare window of L5/S1 disk space was present within this population group, and it was found to be mobile and changed significantly with patient positioning. Therefore, the spine surgeon or the access surgeon must consider the increased potential vascular risk during disk access in lateral decubitus anterior lumbar interbody spinal fusion surgery.

Surgical Outcomes of Multilevel Posterior Lumbar Interbody Fusion versus Lateral Lumbar Interbody Fusion for the Correction of Adult Spinal Deformity: A Comparative Clinical Study

Study Design

A retrospective case control study.

Purpose

The purpose of this study was to compare the surgical outcomes of multilevel lateral lumbar interbody fusion (LIF) and multilevel posterior lumbar interbody fusion (PLIF) in the surgical treatment of adult spinal deformity (ASD) and to evaluate the sagittal plane correction by combining LIF with posterior-column osteotomy (PCO).

Overview of Literature

The surgical outcomes between multilevel LIF and multilevel PLIF in ASD patients remain unclear.

Methods

We retrospectively reviewed 31 ASD patients who underwent multilevel LIF combined with PCO (LIF group, n=14) or multilevel PLIF (PLIF group, n=17) and with a minimum 2-year follow-up. In the comparison between LIF and PLIF groups, their mean age at surgery was 69.4 vs. 61.8 years while the mean follow-up period was 29.2 vs. 59.3 months. We evaluated the transition of pelvic incidence–lumbar lordosis (PI–LL) and disc angle (DA) in the LIF group, in fulcrum backward bending (FBB), after LIF and after posterior spinal fusion (PSF) with PCO. The spinopelvic radiographic parameters were compared between LIF and PLIF groups.

Results

Compared with the PLIF group, the LIF group had less blood loss and comparable surgical outcomes with respect to radiographic data, health-related quality of life scores and surgical time. In the LIF group, the mean DA and PI–LL were unchanged after LIF (DA, 5.8°; PI–LL, 15°) compared with the values using FBB (DA, 4.3°; PI–LL, 15°) and improved significantly after PSF with PCO (DA, 8.1°; PI–LL, 0°).

Conclusions

In the surgical treatment of ASD, multilevel LIF is less invasive than multilevel PLIF and combination of LIF and PCO would be necessary for optimal sagittal correction in patients with rigid deformity.

Interbody Fusions in the Lumbar Spine: A Review

BACKGROUND

Lumbar interbody fusion is among the most common types of spinal surgery performed. Over time, the term has evolved to encompass a number of different approaches to the intervertebral space, as well as differing implant materials. Questions remain over which approaches and materials are best for achieving fusion and restoring disc height.

QUESTIONS/PURPOSES

We reviewed the literature on the advantages and disadvantages of various methods and devices used to achieve and augment fusion between the disc spaces in the lumbar spine.

METHODS

Using search terms specific to lumbar interbody fusion, we searched PubMed and Google Scholar and identified 4993 articles. We excluded those that did not report clinical outcomes, involved cervical interbody devices, were animal studies, or were not in English. After exclusions, 68 articles were included for review.

RESULTS

Posterior approaches have advantages, such as providing 360° support through a single incision, but can result in retraction injury and do not always restore lordosis or correct deformity. Anterior approaches allow for the largest implants and good correction of deformities but can result in vascular, urinary, psoas muscle, or lumbar plexus injury and may require a second posterior procedure to supplement fixation. Titanium cages produce improved osteointegration and fusion rates but also increase subsidence caused by the stiffness of titanium relative to bone. Polyetheretherketone (PEEK) has an elasticity closer to that of bone and shows less subsidence than titanium cages, but as an inert compound PEEK results in lower fusion rates and greater osteolysis. Combination PEEK-titanium coating has not yet achieved better results. Expandable cages were developed to increase disc height and restore lumbar lordosis, but the data on their effectiveness have been inconclusive. Three-dimensionally (3D)-printed cages have shown promise in biomechanical and animal studies at increasing fusion rates and reducing subsidence, but additive manufacturing options are still in their infancy and require more investigation.

CONCLUSIONS

All of the approaches to spinal fusion have plusses and minuses that must be considered when determining which to use, and newer-technology implants, such as PEEK with titanium coating, expandable, and 3D-printed cages, have tried to improve upon the limitations of existing grafts but require further study.

Anterior lumbar compared to oblique lumbar interbody approaches for multilevel fusions to the sacrum in adults with spinal deformity and degeneration

OBJECTIVE

In adult spinal deformity and degenerative conditions of the spine, interbody fusion to the sacrum often is performed to enhance arthrodesis, induce lordosis, and alleviate stenosis. Anterior lumbar interbody fusion (ALIF) has traditionally been performed, but minimally invasive oblique lumbar interbody fusion (OLIF) may or may not cause less morbidity because less retraction of the abdominal viscera is required. The authors evaluated whether there was a difference between the results of ALIF and OLIF in multilevel anterior or lateral interbody fusion to the sacrum.

METHODS

Patients from 2013 to 2018 who underwent multilevel ALIF or OLIF to the sacrum were retrospectively studied. Inclusion criteria were adult spinal deformity or degenerative pathology and multilevel ALIF or OLIF to the sacrum. Demographic, implant, perioperative, and radiographic variables were collected. Statistical calculations were performed for significant differences.

RESULTS

Data from a total of 127 patients were analyzed (66 OLIF patients and 61 ALIF patients). The mean follow-up times were 27.21 (ALIF) and 24.11 (OLIF) months. The mean surgical time was 251.48 minutes for ALIF patients and 234.48 minutes for OLIF patients (p = 0.154). The mean hospital stay was 7.79 days for ALIF patients and 7.02 days for OLIF patients (p = 0.159). The mean time to being able to eat solid food was 4.03 days for ALIF patients and 1.30 days for OLIF patients (p < 0.001). After excluding patients who had undergone L5-S1 posterior column osteotomy, 54 ALIF patients and 41 OLIF patients were analyzed for L5-S1 radiographic changes. The mean cage height was 14.94 mm for ALIF patients and 13.56 mm for OLIF patients (p = 0.001), and the mean cage lordosis was 15.87° in the ALIF group and 16.81° in the OLIF group (p = 0.278). The mean increases in anterior disc height were 7.34 mm and 4.72 mm for the ALIF and OLIF groups, respectively (p = 0.001), and the mean increases in posterior disc height were 3.35 mm and 1.24 mm (p < 0.001), respectively. The mean change in L5-S1 lordosis was 4.33° for ALIF patients and 4.59° for OLIF patients (p = 0.829).

CONCLUSIONS

Patients who underwent multilevel OLIF and ALIF to the sacrum had comparable operative times. OLIF was associated with a quicker ileus recovery and less blood loss. At L5-S1, ALIF allowed larger cages to be placed, resulting in a greater disc height change, but there was no significant difference in L5-S1 segmental lordosis.

The impact of obesity on perioperative complications in patients undergoing anterior lumbar interbody fusion

OBJECTIVE

Anterior approaches to the lumbar spine provide wide exposure that facilitates placement of large grafts with high fusion rates. There are limited data on the effects of obesity on perioperative complications.

METHODS

Data from consecutive patients undergoing anterior lumbar interbody fusion (ALIF) from 2007 to 2016 at a single academic center were analyzed. The primary outcome was any perioperative complication. Complications were divided into those occurring intraoperatively and those occurring postoperatively. Multivariate logistic regression was used to assess the association of obesity and other variables with these complications. An estimation table was used to identify a body mass index (BMI) threshold associated with increased risk of postoperative complication.

RESULTS

A total of 938 patients were identified, and the mean age was 57 years; 511 were females (54.5%). The mean BMI was 28.7 kg/m2, with 354 (37.7%) patients classified as obese (BMI ≥ 30 kg/m2). Forty patients (4.3%) underwent a lateral transthoracic approach, while the remaining 898 (95.7%) underwent a transabdominal retroperitoneal approach. Among patients undergoing transabdominal retroperitoneal ALIF, complication rates were higher for obese patients than for nonobese patients (37.0% vs 28.7%, p = 0.010), a difference that was driven primarily by postoperative complications (36.1% vs 26.0%, p = 0.001) rather than intraoperative complications (3.2% vs 4.3%, p = 0.416). Obese patients had higher rates of ileus (11.7% vs 7.2%, p = 0.020), wound complications (11.4% vs 3.4%, p < 0.001), and urinary tract infections (UTI) (5.0% vs 2.5%, p = 0.049). In a multivariate model, age, obesity, and number of ALIF levels fused were associated with an increased risk of postoperative complication. An estimation table including 19 candidate cut-points, odds ratios, and adjusted p values found a BMI ≥ 31 kg/m2 to have the highest association with postoperative complication (p = 0.012).

CONCLUSIONS

Obesity is associated with increased postoperative complications in ALIF, including ileus, wound complications, and UTI. ALIF is a safe and effective procedure. However, patients with a BMI ≥ 31 kg/m2 should be counseled on their increased risks and warrant careful preoperative medical optimization and close monitoring in the postoperative setting.

Transsacral interbody fixation versus transforaminal lumbar interbody fusion at the lumbosacral junction for long fusions in primary adult scoliosis

OBJECTIVE

Achieving fusion at the lumbosacral junction poses many technical challenges. No data exist in the literature comparing radiographic or clinical outcomes between the different surgical techniques of transsacral fixation (TSF) with rods and transforaminal lumbar interbody fusion (TLIF) in conjunction with iliac fixation. The purpose of this study was to compare the clinical outcomes and radiographic fusions of TSF to TLIF in patients with adult spinal deformity undergoing long fusions across the lumbosacral junction.

METHODS

Patients with primary adult spinal deformity who underwent long fusions from the thoracic spine across the lumbosacral junction with different approaches of interbody fusion at the L5-S1 level were reviewed. Patients were subdivided by approach (TSF vs TLIF). Fusion status at L5-S1 was evaluated by multiple radiographs and/or CT scans. Scoliotic curve changes were also evaluated preoperatively and at final follow-up. Clinical outcomes were assessed by Scoliosis Research Society Outcome Instrument 22 and Oswestry Disability Index scores.

RESULTS

A total of 36 patients were included in the analysis. There were 18 patients in the TSF group and 18 patients in the TLIF group. A mean of 14.00 levels were fused in the TSF group and 10.94 in the TLIF group (p = 0.01). Both groups demonstrated significant postoperative radiographic improvement in coronal parameters. The fusion rates for TSF and TLIF groups were 100% and 88.9%, respectively (p < 0.05). Eight patients in the TSF group had pelvic fixation with unilateral iliac screws, compared to 15 patients in the TLIF group (p = 0.015). No statistical differences in patients' reported outcomes were seen between groups.

CONCLUSIONS

Despite similar clinical and radiographic outcomes between both groups, TSF required fewer iliac screws to augment stability of the lumbosacral junction while achieving a higher rate of fusion. This study suggests that TSF may decrease potential instrument-related complications requiring revision while decreasing operating room time and implant-related costs.

Comparison of rod fracture rates in long spinal deformity constructs after transforaminal versus anterior lumbar interbody fusions: a single-institution analysis

OBJECTIVE

Pseudarthrosis is a common complication of long-segment fusions after surgery for correction of adult spinal deformity (ASD). Interbody fusions are frequently used at the caudal levels of long-segment spinal deformity constructs as adjuncts for anterior column support. There is a paucity of literature comparing rod fracture rates (proxy for pseudarthrosis) in patients undergoing transforaminal lumbar interbody fusion (TLIF) versus anterior lumbar interbody fusion (ALIF) at the caudal levels of the long spinal deformity construct. In this study the authors sought to compare rod fracture rates in patients undergoing surgery for correction of ASD with TLIF versus ALIF at the caudal levels of long spinal deformity constructs.

METHODS

We reviewed clinical records of patients who underwent surgery for correction of ASD between 2008 and 2014 at a single institution. Data including demographics, comorbidities, and indications for surgery, as well as postoperative variables, were collected for each patient. All patients had a minimum 2-year follow-up. Patients were dichotomized into two groups for comparison on the basis of undergoing a TLIF versus an ALIF procedure at the caudal levels of long spinal deformity constructs. The primary outcome of interest was the rate of rod fractures.

RESULTS

A total of 198 patients (TLIF 133 patients; ALIF 65 patients) underwent a long-segment fusion to the sacrum with iliac fixation. The mean ± standard deviation follow-up period was 62.23 ± 29.26 months. Baseline demographic variables were similar in both patient groups. There were no significant differences between groups in the severity of the baseline sagittal plane deformity (i.e., baseline lumbar-pelvic parameters) or the final deformity correction achieved. Mean total recombinant human bone morphogenetic protein 2 (rhBMP-2) dose for L1-sacrum fusion was significantly higher in the ALIF (100 mg) than in the TLIF (62 mg) group. The overall rod failure rate (cases with rod fracture/total cases) within this case series was 19.19% (38/198); 10.60% (21/198) were unilateral rod fractures and 8.58% (17/198) were bilateral rod fractures. At last clinical follow-up, there were no statistically significant differences in bilateral rod fracture rates between the group of patients who had a TLIF procedure and the group who had an ALIF procedure at the caudal levels of the long spinal deformity constructs (TLIF 10.52% vs ALIF 4.61%, p = 0.11). However, the incidence rate (cases per patient follow-up years) for bilateral rod fractures was significantly higher in the TLIF than in the ALIF cohort (TLIF 2.20% vs ALIF 0.70%, p < 0.0001). The reoperation rate for rod fractures was similar between the patient groups (p = 0.40).

CONCLUSIONS

Although both ALIF and TLIF procedures at the caudal levels of long spinal deformity constructs achieved similar and satisfactory deformity correction, ALIFs were associated with a lower rod fracture incidence rate. There were no differences between groups in the prevalence of rod fracture or revision surgery, however, and both groups had low bilateral rod fracture prevalence and incidence rates. One technique is not clearly superior to the other.

Supplemental rods are needed to maximally reduce rod strain across the lumbosacral junction with TLIF but not ALIF in long constructs

BACKGROUND CONTEXT

Rod fracture at the lumbosacral (LS) junction remains challenging in long segment fusions and likely stems from increased LS strain. Reduction of LS instrumentation strain may help reduce fracture rates.

PURPOSE

The goal of this investigation was to assess the effect of supplemental posterior 4-rod (4R) construction on LS stability and rod strain compared with standard 2-rod (2R) construction in a long segment fusion model.

STUDY DESIGN/SETTING

Cadaveric biomechanical study.

OUTCOME MEASURES

Range of motion (ROM), rod strain, and sacral screw (SS) bending moments during flexion, extension, compression, lateral bending, and axial rotation.

METHODS

Standard nondestructive flexibility tests (7.5 Nm) were performed on 14 cadaveric specimens (L1-ilium) to assess ROM stability, rod strain, and SS bending moment of a supplemental 4R construction versus standard 2R construction. Specimens were equally divided into L5-S1 anterior lumbar interbody fusion (ALIF) or L5-S1 transforaminal lumbar interbody fusion (TLIF) groups. Three conditions were tested in each group: (1) no lumbar interbody fusion (No LIF)+2R, (2) ALIF or TLIF+2R, and (3) ALIF or TLIF+4R. Data were analyzed using repeated measures analysis of variance (ANOVA) or ANOVA.

RESULTS

No differences were observed between groups 1 and 2 for age, sex, bone mineral density, or baseline ROM (p>.09). Overall, TLIF+2R demonstrated greater ROM than ALIF+4R in extension (p=003), with greater rod strain in flexion, extension, and compression (p<.001), and greater SS in compression and AR (p<.04). Compared with TLIF+2R, TLIF+4R resulted in reduced rod strain in flexion, extension, compression, and LB (p<.04), as well as SS in AR (p<.001). The TLIF+4R yielded biomechanics comparable to ALIF+2R in ROM and rod strain but SS inflexion, extension, compression, and AR remained elevated (p<001). The ALIF+4R did not significantly improve ROM, rod strain, or SS (p>.11).

CONCLUSIONS

The use of ALIF and adding accessory rods with TLIF significantly reduced LS rod strain in a long segment cadaveric model with iliac fixation.

CLINICAL SIGNIFICANCE

Reducing strain could decrease the risk of failure associated with long segment fixation.

The utilization of minimally invasive surgery techniques for the treatment of spinal deformity

Minimally invasive spinal surgery (MISS) has evolved as a formidable alternative to traditional open techniques to address adult spinal deformity (ASD). As technology advances, an increasingly large body of techniques and implants are available for use in MISS deformity correction. MISS deformity correction includes anterior, lateral, and posterior techniques that can be tailored to each patient while capturing the strength of each respective technique. Previous limitations of obtaining sagittal correction have been overcome with anterior column realignment (ACR) and the mini-open pedicle subtraction osteotomy. This article will describe current techniques and their application for ASD correction.

Iliac screws may not be necessary in long-segment constructs with L5-S1 anterior lumbar interbody fusion: cadaveric study of stability and instrumentation strain

BACKGROUND CONTEXT

Lumbosacral pseudoarthrosis and instrumentation failure is common with long-segment constructs. Optimizing lumbosacral construct biomechanics may help to reduce failure rates. The influence of iliac screws and interbody type on range of motion (ROM), rod strain (RS), sacral screw strain (SS) is not well-established.

PURPOSE

Investigate the effects of transforaminal lumbar interbody fusion (TLIF), anterior lumbar interbody fusion (ALIF), and iliac screws on long-segment lumbosacral construct biomechanics.

STUDY DESIGN

Biomechanical study.

PATIENT SAMPLE

Fourteen human cadaveric spine specimens.

OUTCOME MEASURES

Lumbosacral ROM, RS, and SS.

METHODS

Specimens were potted at L1 and the ilium. Specimens were equally divided into either an L5-S1 ALIF or TLIF group and underwent testing in the following conditions: (1) intact (2) L2-S1 pedicle screw rod fixation (PSR-S) (3) L2-ilium (PSR-I) (4) PSR-S+ALIF (ALIF-S) or TLIF (TLIF-S) (5) PSR-I + ALIF (ALIF-I) or TLIF (TLIF-I). Pure moment bending (7.5 Nm) in flexion, extension, lateral bending, axial rotation, and compressive loads (400N) were applied and ROM, SS, and RS were measured. Comparisons were performed using a one-way ANOVA (p<.05).

RESULTS

ALIF-S and TLIF-S provided similar decreases in ROM as TLIF-I (p>.05). Compared to PSR-S, PSR-I significantly decreased SS during bending in all directions (p<.02) but increased RS in flexion and extension (p≤.02). Anterior lumbar interbody fusion-S provided similar decreases in SS as TLIF-I in all directions (p>.40) but had significantly less RS than TLIF-I in flexion, extension, compression (p<.01). TLIF-S had more SS than TLIF-I in flexion, extension, axial rotation (p<.02), while TLIF-S had less RS only in flexion (p=.03). Compared to PSR-I, ALIF-I decreased the RS (p<.02) but TLIF-I did not (p>.67).

CONCLUSIONS

Iliac screws were protective of SS but increased RS at the lumbosacral junction. Constructs with ALIF and no iliac screws result in comparable SS as constructs with TLIF and iliac screws with significantly reduced RS. If iliac screws are utilized, ALIF but not TLIF reduces the iliac screw-induced RS.

CLINICAL SIGNIFICANCE

There is a relatively high incidence of lumbosacral instrumentation failure in adult spinal deformity. Optimizing lumbosacral construct biomechanics may help to reduce failure rates. Iliac screws induce lumbosacral rod strain and may be responsible for instrumentation failure. Constructs with lumbosacral ALIF reduce iliac-screw induced rod strain and may obviate the need for fixation to the ilium.

Comparative study of multilevel posterior interbody fusion plus anterior longitudinal ligament release versus classic multilevel posterior interbody fusion in the treatment of adult spinal deformities

OBJECTIVE

Sagittal imbalance and loss of lumbar lordosis are the main drivers of functional disability in adult degenerative scoliosis. The main limitations of the classic posterior lumbar interbody fusion technique are increased risk of neurological injury and suboptimal correction of the segmental lordosis. Here, the authors describe the radiological results of a modified posterior lumbar interbody fusion and compare the results with a historical cohort of patients.

METHODS

Eighty-two consecutive patients underwent surgical treatment for degenerative scoliosis/kyphosis in a single tertiary referral center for complex spinal surgery. Fifty-five patients were treated using the classic multilevel posterior lumbar interbody fusion (MPLIF) technique and 27 were treated using the modified MPLIF technique to include a release of the anterior longitudinal ligament (ALL) and the annulus. A radiographic review of both series of patients was performed by two independent observers. Functional outcomes were obtained, and patients were registered in the European Spine Tango registry.

RESULTS

The mean L4-5 disc angle increased by 3.14° in the classic MPLIF group and by 12.83° in MPLIF plus ALL and annulus release group. The mean lumbar lordosis increased by 15.23° in the first group and by 25.17° in the second group. The L4-S1 lordosis increased on average by 4.92° in the classic MPLIF group and increased by a mean of 23.7° in the MPLIF plus ALL release group when both L4-5 and L5-S1 segments were addressed. There were significant improvements in the Core Outcome Measures Index and EQ-5D score in both groups (p < 0.001). There were no vascular or neurological injuries observed in either group.

CONCLUSIONS

The authors' preliminary results suggest that more correction can be achieved at the disc level using posterior-based ALL and annulus release in conjunction with posterior lumbar interbody fusion. They demonstrate that ALL and annulus release can be performed safely using a posterior-only approach with minimal risk of vascular injury. However, the authors recommend that this approach should only be used by surgeons with considerable experience in anterior and posterior spinal surgery.