A comparison of modern-era anterior lumbar interbody fusion and minimally invasive transforaminal lumbar interbody fusion at the lumbosacral junction

J Neurosurg Spine 39:785–792, 2023

Interbody fusion is the primary method for achieving arthrodesis across the lumbosacral junction in the setting of degenerative pathologies, such as spondylosis and spondylolisthesis. Two common techniques are anterior lumbar interbody fusion (ALIF) and posterior transforaminal lumbar interbody fusion (TLIF). In recent years, interbody design and technology have advanced, and most earlier studies comparing ALIF and TLIF did not specifically assess the lumbosacral junction. This study compared changes in radiographic and clinical parameters between patients undergoing modern-era single-level ALIF and minimally invasive surgery (MIS) TLIF at L5–S1.

METHODS Consecutive patients who underwent single-segment L5–S1 ALIF or MIS TLIF performed by the senior authors over a 6-year interval (January 1, 2016–November 30, 2021) were retrospectively reviewed. Upright radiographs were used to determine pre- and postoperative lumbar lordosis, segmental lordosis, disc angle, and neuroforaminal height. Improvements in patient-reported outcome scores (Oswestry Disability Index and SF-36) were also compared.

RESULTS Overall, 108 patients (58 [54%] men, 50 [46%] women; mean [SD] age 57.6 [13.5] years) were included in the study. ALIF was performed in 49 patients, and TLIF was performed in 59 patients. The most common treatment indications were spondylolisthesis (50%, 54/108) and spondylosis (46%, 50/108). The cohorts did not differ in terms of intraoperative (p > 0.99) or postoperative (p = 0.73) complication rates. The mean (SD) hospital length of stay was significantly shorter for patients undergoing TLIF than ALIF (1.3 [0.6] days vs 2.0 [1.4] days, p < 0.001). Both techniques significantly improved L5–S1 segmental lordosis, disc angle, and neuroforaminal height (p ≤ 0.008). ALIF versus TLIF significantly increased mean [SD] segmental lordosis (12.5° [7.3°] vs 2.0° [5.7°], p < 0.001), disc angle (14.8° [5.5°] vs 3.0° [6.1°], p < 0.001), and neuroforaminal height (4.5 [4.6] mm vs 2.4 [3.0] mm, p = 0.008). Improvements in patient-reported outcome parameters and reoperation rates were similar between cohorts.

CONCLUSIONS When treating patients at a single segment across the lumbosacral junction, ALIF resulted in significantly greater increases in segmental lordosis, L5–S1 disc angle, and neuroforaminal height compared with MIS TLIF. Improvements in clinical parameters and reoperation rates were similar between the 2 techniques.

Minimally Invasive Transforaminal Lumbar Interbody Fusion in the Ambulatory Surgery Center Versus Inpatient Setting: A 1-Year Comparative Effectiveness Analysis

Neurosurgery 93:867–874, 2023

Ambulatory surgery centers (ASCs) have emerged as an alternative setting for surgical care as part of the national effort to lower health care costs. The literature regarding the safety of minimally invasive transforaminal lumbar interbody fusion (MIS TLIF) in the ASC setting is limited to few small case series.

OBJECTIVE: To assess the safety and efficacy of MIS TLIF performed in the ASC vs inpatient hospital setting.

METHODS: A total of 775 patients prospectively enrolled in the Quality Outcomes Database undergoing single-level MIS TLIF at a single ASC (100) or the inpatient hospital setting (675) were compared. Propensity matching generated 200 patients for analysis (100 per cohort). Demographic data, resource utilization, patient-reported outcome measures (PROMs), and patient satisfaction were assessed.

RESULTS: There were no significant differences regarding baseline demographic data, clinical history, or comorbidities after propensity matching. Only 1 patient required inpatient transfer from the ASC because of intractable pain. All other patients were discharged home within 23 hours of surgery. The rates of 90-day readmission (2.0%) and reoperation (0%) were equivalent between groups. Both groups experienced significant improvements in all PROMs (Oswestry Disability Index, EuroQol-5D, back pain, and leg pain) at 3 months that were maintained at 1 year. PROMs did not differ between groups at any time point. Patient satisfaction was similar between groups at 3 and 12 months after surgery.

CONCLUSION: In carefully selected patients, MIS TLIF may be performed safely in the ASC setting with no statistically significant difference in safety or efficacy in comparison with the inpatient setting.

Clinical Outcomes of Liposomal Bupivacaine Erector Spinae Block in Minimally Invasive Transforaminal Lumbar Interbody Fusion Surgery

Neurosurgery 92:590–598, 2023

Postoperative pain is a barrier to early mobility and discharge after lumbar surgery. Liposomal bupivacaine (LB) has been shown to decrease postoperative pain and narcotic consumption after transforaminal lumbar interbody fusions (TLIFs) when injected into the marginal suprafascial/subfascial plane-liposomal bupivacaine (MSSP-LB). Erector spinae plane (ESP) infiltration is a relatively new analgesic technique that may offer additional benefits when performed in addition to MSSP-LB.

OBJECTIVE: To evaluate postoperative outcomes of combining ESP-LB with MSSP-LB compared with MSSP-LB alone after single-level TLIF.

METHODS: A retrospective analysis was performed for patients undergoing single-level TLIFs under spinal anesthesia, 25 receiving combined ESP-LB and MSSP-LB and 25 receiving MSSP-LB alone. The primary outcome was length of hospitalization. Secondary outcomes included postoperative pain score, time to ambulation, and narcotics usage.

RESULTS: Baseline demographics and length of surgery were similar between groups. Hospitalization was significantly decreased in the ESP-LB + MSSP-LB cohort (2.56 days vs 3.36 days, P = .007), as were days to ambulation (0.96 days vs 1.29 days, P = .026). Postoperative pain area under the curve was significantly decreased for ESP-LB + MSSP-LB at 12 to 24 hours (39.37 ± 21.02 vs 53.38 ± 22.11, P = .03) and total (44.46 ± 19.89 vs 50.51 ± 22.15, P = .025). Postoperative narcotic use was significantly less in the ESP-LB + MSSP-LB group at 12 to 24 hours (13.18 ± 4.65 vs 14.78 ± 4.44, P = .03) and for total hospitalization (137.3 ± 96.3 vs 194.7 ± 110.2, P = .04).

CONCLUSION: Combining ESP-LB with MSSP-LB is superior to MSSP-LB alone for single level TLIFs in decreasing length of hospital stay, time to ambulation, postoperative pain, and narcotic use.

Comparison of local and regional radiographic outcomes in minimally invasive and open TLIF

J Neurosurg Spine 37:384–394, 2022

Local and regional radiographic outcomes following minimally invasive (MI) transforaminal lumbar interbody fusion (TLIF) versus open TLIF remain unclear. The purpose of this study was to provide a comprehensive assessment of local and regional radiographic parameters following MI-TLIF and open TLIF. The authors hypothesized that open TLIF provides greater segmental and global lordosis correction than MI-TLIF.

METHODS A single-center retrospective cohort study of consecutive patients undergoing MI- or open TLIF for grade I degenerative spondylolisthesis was performed. One-to-one nearest-neighbor propensity score matching (PSM) was used to match patients who underwent open TLIF to those who underwent MI-TLIF. Sagittal segmental radiographic measures included segmental lordosis (SL), anterior disc height (ADH), posterior disc height (PDH), foraminal height (FH), percent spondylolisthesis, and cage position. Lumbopelvic radiographic parameters included overall lumbar lordosis (LL), pelvic incidence (PI)–lumbar lordosis (PI-LL) mismatch, sacral slope (SS), and pelvic tilt (PT). Change in segmental or overall lordosis after surgery was considered “lordosing” if the change was > 0° and “kyphosing” if it was ≤ 0°. Student t-tests or Wilcoxon rank-sum tests were used to compare outcomes between MI-TLIF and open-TLIF groups.

RESULTS A total of 267 patients were included in the study, 114 (43%) who underwent MI-TLIF and 153 (57%) who underwent open TLIF, with an average follow-up of 56.6 weeks (SD 23.5 weeks). After PSM, there were 75 patients in each group. At the latest follow-up both MI- and open-TLIF patients experienced significant improvements in assessment scores obtained with the Oswestry Disability Index (ODI) and the numeric rating scale for low-back pain (NRS-BP), without significant differences between groups (p > 0.05). Both MI- and open-TLIF patients experienced significant improvements in SL, ADH, and percent corrected spondylolisthesis compared to baseline (p < 0.001). However, the MI-TLIF group experienced significantly larger magnitudes of correction with respect to these metrics (ΔSL 4.14° ± 4.35° vs 1.15° ± 3.88°, p < 0.001; ΔADH 4.25 ± 3.68 vs 1.41 ± 3.77 mm, p < 0.001; percent corrected spondylolisthesis: −10.82% ± 6.47% vs −5.87% ± 8.32%, p < 0.001). In the MI-TLIF group, LL improved in 44% (0.3° ± 8.5°) of the cases, compared to 48% (0.9° ± 6.4°) of the cases in the open-TLIF group (p > 0.05). Stratification by operative technique (unilateral vs bilateral facetectomy) and by interbody device (static vs expandable) did not yield statistically significant differences (p > 0.05).

CONCLUSIONS Both MI- and open-TLIF patients experienced significant improvements in patient-reported outcome (PRO) measures and local radiographic parameters, with neutral effects on regional alignment. Surprisingly, in our cohort, change in SL was significantly greater in MI-TLIF patients, perhaps reflecting the effect of operative techniques, technological innovations, and the preservation of the posterior tension band. Taking these results together, no significant overall differences in LL between groups were demonstrated, which suggests that MI-TLIF is comparable to open approaches in providing radiographic correction after surgery. These findings suggest that alignment targets can be achieved by either MI- or open-TLIF approaches, highlighting the importance of surgeon attention to these variables.

Radiographic and clinical outcomes in one- and two-level transforaminal lumbar interbody fusions: a comparison of bullet versus banana cages

J Neurosurg Spine 36:918–927, 2022

The aim of this study was to determine whether cage morphology influences clinical and radiographic outcomes following short-segment transforaminal lumbar interbody fusion (TLIF) procedures.

METHODS The authors retrospectively reviewed one- and two-level TLIFs at a single tertiary care center between August 2012 and November 2019 with a minimum 1-year radiographic and clinical follow-up. Two cohorts were compared based on interbody cage morphology: steerable “banana” cage or straight “bullet” cage. Patient-reported outcome measures (PROMs), radiographs, and complications were analyzed.

RESULTS A total of 135 patients with 177 interbody levels were identified; 45 patients had 52 straight cages and 90 patients had 125 steerable cages. Segmental lordosis increased with steerable cages, while it decreased with straight cages (+3.8 ± 4.6 vs −1.9 ± 4.3, p < 0.001). Conversely, the mean segmental lordosis of adjacent lumbar levels decreased in the former group, while it increased in the latter group (−0.52 ± 1.9 vs +0.52 ± 2.1, p = 0.004). This reciprocal relationship results in global sagittal parameters, including pelvic incidence minus lumbar lordosis and lumbar distribution index, which did not change after surgery with either cage morphology. Multivariate analysis confirmed that steerable cage morphology, anterior cage positioning, and less preoperative index-level segmental lordosis were associated with greater improvement in index-level segmental lordosis. PROMs were improved after surgery with both cage types, and the degree of improvement did not differ between cohorts (p > 0.05). Perioperative and radiographic complications were similar between cohorts (p > 0.05). Overall reoperation rates, as well as reoperation rates for adjacent-segment disease within 2 years of surgery, were not significantly different between cohorts.

CONCLUSIONS Steerable cages are more likely to lie within the anterior disc space, thus increasing index-level segmental lordosis, which is accompanied by a reciprocal change in segmental alignment at the adjacent lumbar levels. The converse relationship occurs for straight cages, with a kyphotic change at the index levels and reciprocal lordosis occurring at adjacent levels.


Minimally Invasive Transforaminal Lumbar Interbody Fusion: Cost of a Surgeon’s Learning Curve

World Neurosurg. (2022) 162:e1-e7

Minimally invasive transforaminal interbody fusion has become an increasingly common approach in adult degenerative spine disease but is associated with a steep learning curve. We sought to evaluate the impact of the learning experience on mean procedure time and mean cost associated with each procedure.

METHODS: We studied the first 100 consecutive minimally invasive transforaminal interbody fusion procedures of a single surgeon. We performed multivariable linear regression models, modeling operating time, and costs in function of the procedure order adjusted for patients’ age, sex, and number of surgical levels. The number of procedures necessary to attain proficiency was determined through a k-means cluster analysis. Finally, the total excess operative time and total excess cost until obtaining proficiency was evaluated.

RESULTS: Procedure order was found to impact procedure time and mean costs, with each successive case being associated with progressively less procedure time and cost. On average, each successive case was associated with a reduction in procedure time of 0.97 minutes (95% confidence interval 0.54e1.40; P < 0.001) and an average adjusted reduction in overall costs of $82.75 (95% confidence interval $35.93e129.57; P < 0.001). An estimated 58 procedures were needed to attain proficiency, translating into an excess procedure time of 2604.2 minutes (average of 45 minutes per case), overall costs associated with the learning experience of $226,563.8 (average of $3974.80 per case), and excess surgical cost of $125,836.6 (average of $2207.66 per case).

CONCLUSIONS: Successive cases were associated with progressively less procedure time and mean overall and surgical costs, until a proficiency threshold was attained.

Robotic-Assisted vs Nonrobotic-Assisted Minimally Invasive Transforaminal Lumbar Interbody Fusion: A Cost-Utility Analysis

Neurosurgery 90:192–198, 2022

Management of degenerative disease of the spine has evolved to favor minimally invasive techniques, including nonrobotic-assisted and robotic-assisted minimally invasive transforaminal lumbar interbody fusion (MIS-TLIF). Value-based spending is being increasingly implemented to control rising costs in the US healthcare system. With an aging population, it is fundamental to understand which procedure(s) may be most cost-effective.

OBJECTIVE: To compare robotic and nonrobotic MIS-TLIF through a cost-utility analysis.

METHODS: We considered direct medical costs related to surgical intervention and to the hospital stay, as well as 1-yr utilities. We estimated costs by assessing all cases involving adults undergoing robotic surgery at a single institution and an equal number of patients undergoing nonrobotic surgery, matched by demographic and clinical characteristics. We adopted a willingness to pay of $50 000/quality-adjusted life year (QALY). Uncertainty was addressed by deterministic and probabilistic sensitivity analyses.

RESULTS: Costs were estimated based on a total of 76 patients, including 38 undergoing robot-assisted and 38 matched patients undergoing nonrobot MIS-TLIF. Using point estimates, robotic surgery was projected to cost $21 546.80 and to be associated with 0.68 QALY, and nonrobotic surgery was projected to cost $22 398.98 and to be associated with 0.67 QALY. Robotic surgery was found to be more cost-effective strategy, with costeffectiveness being sensitive operating room/materials and room costs. Probabilistic sensitivity analysis identified robotic surgery as cost-effective in 63% of simulations.

CONCLUSION: Our results suggest that at a willingness to pay of $50 000/QALY, robotic assisted MIS-TLIF was cost-effective in 63% of simulations. Cost-effectiveness depends on operating room and room (admission) costs, with potentially different results under distinct neurosurgical practices.

Does transforaminal lumbar interbody fusion induce lordosis or kyphosis?

J Neurosurg Spine 35:419–426, 2021

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.

Transforaminal lumbar interbody fusion using a novel minimally invasive expandable interbody cage

J Neurosurg Spine 35:170–176, 2021

The goal of this study was to evaluate the clinical and radiographic outcomes of a novel multidirectional in situ expandable minimally invasive surgery (MIS) transforaminal lumbar interbody fusion (TLIF) cage.

METHODS A retrospective analysis of 69 consecutive patients undergoing a 1- or 2-level MIS TLIF using an expandable cage was performed over a 2-year period. Standard MIS techniques with pedicle screw fixation were used in all cases. Upright lateral dynamic flexion/extension radiographs were reviewed prior to and at 1 year after surgery. Clinical metrics included numeric rating scale for back and leg pain, Oswestry Disability Index, and the SF-12 and VR-12 physical and mental health surveys. Radiographic parameters included anterior and posterior disc height, neuroforaminal height, spondylolisthesis, segmental lordosis, lumbar lordosis, and fusion rate.

RESULTS A total of 69 patients representing 75 operative levels met study inclusion criteria. The mean patient age at surgery was 63.4 ± 1.2 years, with a female predominance of 51%. The average radiographic and clinical follow-ups were 372 and 368 days, respectively. A total of 63 patients (91%) underwent 1-level surgery and 6 patients (9%) underwent 2-level surgery. Significant reductions of numeric rating scale scores for back and leg pain were observed—from 6.1 ± 0.7 to 2.5 ± 0.3 (p < 0.0001) and 4.9 ± 0.6 to 1.9 ± 0.2 (p < 0.0001), respectively. A similar reduction in Oswestry Disability Index from 38.0 ± 4.6 to 20.0 ± 2.3 (p < 0.0001) was noted. Likewise, SF-12 and VR-12 scores all showed statistically significant improvement from baseline (p < 0.001). The mean anterior and posterior disc heights improved from 8.7 ± 1.0 mm to 13.4 ± 1.5 mm (p = 0.0001) and 6.5 ± 0.8 mm to 9.6 ± 1.1 mm (p = 0.0001), respectively. Neuroforaminal height improved from 17.6 ± 2.0 mm to 21.9 ± 2.5 mm (p = 0.0001). When present, spondylolisthesis was, on average, reduced from 4.3 ± 0.5 mm to 1.9 ± 0.2 mm (p = 0.0001). Lumbar lordosis improved from 47.8° ± 5.5° to 58.5° ± 6.8° (p = 0.2687), and no significant change in segmental lordosis was observed. The overall rate of radiographic fusion was 93.3% at 1 year. No perioperative complications requiring operative revision were encountered.

CONCLUSIONS In this series of MIS TLIFs, use of this novel interbody cage was shown to be safe and effective. Significant improvements in pain and disability were observed. Effective and durable restoration of disc height and neuroforaminal height and reduction of spondylolisthesis were obtained, with concurrent gains in lumbar lordosis. Taken together, this device offers excellent clinical and radiographic outcomes via an MIS approach.

Long-term radiographic outcomes of expandable versus static cages in transforaminal lumbar interbody fusion

J Neurosurg Spine 34:471–480, 2021

Potential advantages of using expandable versus static cages during transforaminal lumbar interbody fusion (TLIF) are not fully established. The authors aimed to compare the long-term radiographic outcomes of expandable versus static TLIF cages.

METHODS A retrospective review of 1- and 2-level TLIFs over a 10-year period with expandable and static cages was performed at the University of California, San Francisco. Patients with posterior column osteotomy (PCO) were subdivided. Fusion assessment, cage subsidence, anterior and posterior disc height, foraminal dimensions, pelvic incidence (PI), segmental lordosis (SL), lumbar lordosis (LL), pelvic incidence–lumbar lordosis mismatch (PI-LL), pelvic tilt (PT), sacral slope (SS), and sagittal vertical axis (SVA) were assessed.

RESULTS A consecutive series of 178 patients (with a total of 210 levels) who underwent TLIF using either static (148 levels) or expandable cages (62 levels) was reviewed. The mean patient age was 60.3 ± 11.5 years and 62.8 ± 14.1 years for the static and expandable cage groups, respectively. The mean follow-up was 42.9 ± 29.4 months for the static cage group and 27.6 ± 14.1 months for the expandable cage group. Within the 1-level TLIF group, the SL and PI-LL improved with statistical significance regardless of whether PCO was performed; however, the static group with PCOs also had statistically significant improvement in LL and SVA. The expandable cage with PCO subgroup had significant improvement in SL only. All of the foraminal parameters improved with statistical significance, regardless of the type of cages used; however, the expandable cage group had greater improvement in disc height restoration. The incidence of cage subsidence was higher in the expandable group (19.7% vs 5.4%, p = 0.0017). Within the expandable group, the unilateral facetectomy-only subgroup had a 5.6 times higher subsidence rate than the PCO subgroup (26.8% vs 4.8%, p = 0.04). Four expandable cages collapsed over time.

CONCLUSIONS Expandable TLIF cages may initially restore disc height better than static cages, but they also have higher rates of subsidence. Unilateral facetectomy alone may result in more subsidence with expandable cages than using bilateral PCO, potentially because of insufficient facet release. Although expandable cages may have more power to induce lordosis and restore disc height than static cages, subsidence and endplate violation may negate any significant gains compared to static cages.


Is the Goutallier grade of multifidus fat infiltration associated with adjacent-segment degeneration after lumbar spinal fusion?

J Neurosurg Spine 34:190–195, 2021

The aim of this study was to investigate whether fat infiltration of the lumbar multifidus (LM) muscle affects revision surgery rates for adjacent-segment degeneration (ASD) after L4–5 transforaminal lumbar interbody fusion (TLIF) for degenerative spondylolisthesis.

METHODS A total of 178 patients undergoing single-level L4–5 TLIF for spondylolisthesis (2006 to 2016) were retrospectively analyzed. Inclusion criteria were a minimum 2-year follow-up, preoperative MR images and radiographs, and single-level L4–5 TLIF for degenerative spondylolisthesis. Twenty-three patients underwent revision surgery for ASD during the follow-up. Another 23 patients without ASD were matched with the patients with ASD. Demographic data, Roussouly curvature type, and spinopelvic parameter data were collected. The fat infiltration of the LM muscle (L3, L4, and L5) was evaluated on preoperative MRI using the Goutallier classification system.

RESULTS A total of 46 patients were evaluated. There were no differences in age, sex, BMI, or spinopelvic parameters with regard to patients with and those without ASD (p > 0.05). Fat infiltration of the LM was significantly greater in the patients with ASD than in those without ASD (p = 0.029). Fat infiltration was most significant at L3 in patients with ASD than in patients without ASD (p = 0.017). At L4 and L5, there was an increasing trend of fat infiltration in the patients with ASD than in those without ASD, but the difference was not statistically significant (p = 0.354 for L4 and p = 0.077 for L5).

CONCLUSIONS Fat infiltration of the LM may be associated with ASD after L4–5 TLIF for spondylolisthesis. Fat infiltration at L3 may also be associated with ASD at L3–4 after L4–5 TLIF.

Functional and radiological outcome of anterior retroperitoneal versus posterior transforaminal interbody fusion in the management of single-level lumbar degenerative disease

Neurosurg Focus 49 (3):E2, 2020

In this study the authors compared the anterior lumbar interbody fusion (ALIF) and posterior transforaminal lumbar interbody fusion (TLIF) techniques in a homogeneous group of patients affected by single-level L5–S1 degenerative disc disease (DDD) and postdiscectomy syndrome (PDS). The purpose of the study was to analyze perioperative, functional, and radiological data between the two techniques.

METHODS A retrospective analysis of patient data was performed between 2015 and 2018. Patients were clustered into two homogeneous groups (group 1 = ALIF, group 2 = TLIF) according to surgical procedure. A statistical analysis of clinical perioperative and radiological findings was performed to compare the two groups. A senior musculoskeletal radiologist retrospectively revised all radiological images.

RESULTS Seventy-two patients were comparable in terms of demographic features and surgical diagnosis and included in the study, involving 32 (44.4%) male and 40 (55.6%) female patients with an average age of 47.7 years. The mean follow-up duration was 49.7 months. Thirty-six patients (50%) were clustered in group 1, including 31 (86%) with DDD and 5 (14%) with PDS. Thirty-six patients (50%) were clustered in group 2, including 28 (78%) with DDD and 8 (22%) with PDS. A significant reduction in surgical time (107.4 vs 181.1 minutes) and blood loss (188.9 vs 387.1 ml) in group 1 (p < 0.0001) was observed. No significant differences in complications and reoperation rates between the two groups (p = 0.561) was observed. A significant improvement in functional outcome was observed in both groups (p < 0.001), but no significant difference between the two groups was found at the last follow-up. In group 1, a faster median time of return to work (2.4 vs 3.2 months) was recorded. A significant improvement in L5–S1 postoperative lordosis restoration was registered in the ALIF group (9.0 vs 5.0, p = 0.023).

CONCLUSIONS According to these results, interbody fusion is effective in the surgical management of discogenic pain. Even if clinical benefits were achieved earlier in the ALIF group (better scores and faster return to work), both procedures improved functional outcomes at last follow-up. The ALIF group showed significant reduction of blood loss, shorter surgical time, and better segmental lordosis restoration when compared to the TLIF group. No significant differences in postoperative complications were observed between the groups. Based on these results, the ALIF technique enhances radiological outcome improvement in spinopelvic parameters when compared to TLIF in the management of adult patients with L5–S1 DDD.

A Comparison of Minimally Invasive and Open Transforaminal Lumbar Interbody Fusion for Grade 1 Degenerative Lumbar Spondylolisthesis

Neurosurgery DOI:10.1093/neuros/nyaa097

It remains unclear if minimally invasive transforaminal lumbar interbody fusion (MI-TLIF) is comparable to traditional, open TLIF because of the limitations of the prior small-sample-size, single-center studies reporting comparative effectiveness.

OBJECTIVE: To compare MI-TLIF to traditional, open TLIF for grade 1 degenerative lumbar spondylolisthesis in the largest study to date by sample size.

METHODS: We utilized the prospective Quality Outcomes Database registry and queried patients with grade 1 degenerative lumbar spondylolisthesis who underwent singlesegment surgery with MI- or open TLIF methods. Outcomes were compared 24 mo postoperatively.

RESULTS: A total of 297 patients were included: 72 (24.2%) MI-TLIF and 225 (75.8%) open TLIF. MI-TLIF surgeries had lower mean body mass indexes (29.5±5.1 vs 31.3±7.0, P=.0497) and more worker’s compensation cases (11.1% vs 1.3%, P< .001) but were otherwise similar. MI-TLIF had less blood loss (108.8 ± 85.6 vs 299.6 ± 242.2 mL, P < .001), longer operations (228.2 ± 111.5 vs 189.6 ± 66.5 min, P < .001), and a higher return-to-work (RTW) rate (100% vs 80%, P = .02). Both cohorts improved significantly from baseline for 24-mo Oswestry Disability Index (ODI), Numeric Rating Scale back pain (NRS-BP), NRS leg pain (NRS-LP), and Euro-Qol-5 dimension (EQ-5D) (P > .001). In multivariable adjusted analyses, MI-TLIF was associated with lower ODI (β =−4.7; 95% CI=−9.3 to −0.04; P= .048), higher EQ-5D (β =0.06; 95% CI=0.01-0.11; P=.02), and higher satisfaction (odds ratio for North American Spine Society [NASS] 1/2 = 3.9; 95% CI = 1.4-14.3; P = .02). Though trends favoring MI-TLIF were evident for NRS-BP (P = .06), NRS-LP (P = .07), and reoperation rate (P = .13), these results did not reach statistical significance.

CONCLUSION: For single-level grade 1 degenerative lumbar spondylolisthesis, MI-TLIF was associated with less disability, higher quality of life, and higher patient satisfaction compared with traditional, open TLIF. MI-TLIF was associated with higher rates of RTW, less blood loss, but longer operative times. Though we utilized multivariable adjusted analyses, these findings may be susceptible to selection bias.

Predictors of Poor Outcome in Patients Submitted to Minimally Invasive Transforaminal Lumbar Interbody Fusion

World Neurosurg. (2018) 119:488-493

Minimally invasive transforaminal lumbar interbody fusion (MI-TLIF) has become an increasingly popular method for lumbar arthrodesis. While having similar long-term outcomes when compared with open TLIF, it decreases the amount of intraoperative blood loss and iatrogenic muscle damage, the intensity of postoperative pain, and the duration of hospital stay. However, uncertainty remains about which factors contribute to outcomes in these patients. The purpose of this study was to retrospectively analyze a cohort of patients submitted to MI-TLIF and to identify factors that can be associated with a worse postoperative outcome.

METHODS: Clinical records from 283 patients were assessed and, according to Odom’s criteria, postoperative clinical outcome at 12 months was classified as excellent, good, fair, and poor. Demographic variables, clinical data, and surgery-related data were analyzed, looking for associations between them and clinical outcome. A binomial logistic regression analysis was then performed to include those associations.

RESULTS: The main variables associated with worse prognosis (“poor” class according to Odom’s criteria) were a period of sick leave longer than 3 months before the surgery, age younger than 50 years, lytic spondylolisthesis, L5-S1 level, and occurrence of complications. These 5 conditions were included in a logistic regression analysis, and 3 of them were independently associated with poor outcome: operative complications, age younger than 50 years, and sick leave longer than 3 months before surgery. –

CONCLUSIONS: Younger patients, those on a sick leave for more than 3 months before surgery, or those who suffered surgical complications tended to have less satisfactory results after MI-TLIF.

Expandable vs Static Cages in Transforaminal Lumbar Interbody Fusion

Neurosurgery 81:69–74, 2017

One criticism of transforaminal lumbar interbody fusion (TLIF) is the inability to increase segmental lordosis (SL). Expandable interbody cages are a relatively new innovation theorized to allow improvement in SL.

OBJECTIVE: To compare changes in SL and lumbar lordosis (LL) after TLIF with nonexpandable vs expandable cages. METHODS: We performed a retrospective cohort study of patients who were ≥18 years old and underwent single-level TLIF between 2011 and 2014. Patients were categorized by cage type (static vs expandable). Primary outcome of interestwas change in SL and LL from preoperative values to those at 1 month and 1 year postoperatively.

RESULTS: A total of 89 patients were studied (48 nonexpandable group, 41 expandable group). Groups had similar baseline characteristics. For SL, median (interquartile range) improvement was 3◦ for nonexpandable and 2◦ for expandable (unadjusted, P = .09; adjusted, P = .68) at 1 month postoperatively, and 3◦ for nonexpandable and 1◦ for expandable (unadjusted, P=.41; adjusted, P=.28) at 1 year postoperatively. For LL, median improvement was 1◦ for nonexpandable and 2◦ for expandable (unadjusted, P = .20; adjusted, P = .21), and 2◦ for nonexpandable and 5◦ for expandable (unadjusted, P = .15; adjusted, P=.51) at 1 year postoperatively. After excluding parallel expandable cages, there was still no difference in SL or LL improvement at 1month or 1 year postoperatively between static and expandable cages (both unadjusted and adjusted, P > .05).

CONCLUSION: Patients undergoing single-level TLIF experienced similar improvements in SL and LL regardless of whether nonexpandable or expandable cages were placed.

The Influence of Pelvic Incidence and Lumbar Lordosis Mismatch on Development of Symptomatic Adjacent Level Disease Following Single-Level Transforaminal Lumbar Interbody Fusion

Neurosurgery 80:880–886, 2017

Annual incidence of symptomatic adjacent level disease (ALD) following lumbar fusion surgery ranges from 0.6% to 3.9% per year. Sagittal malalignment may contribute to the development of ALD.

OBJECTIVE: To describe the relationship between pelvic incidence-lumbar lordosis (PI-LL) mismatch and the development of symptomatic ALD requiring revision surgery following single-level transforaminal lumbar interbody fusion for degenerative lumbar spondylosis and/or low-grade spondylolisthesis.

METHODS: All patients who underwent a single-level transforaminal lumbar interbody fusion at either L4/5 or L5/S1 between July 2006 and December 2012 were analyzed for pre- and postoperative spinopelvic parameters. Using univariate and logistic regression analysis,we compared the spinopelvic parameters of those patients who required revision surgery against those patients who did not develop symptomatic ALD. We calculated the predictive value of PI-LL mismatch.

RESULTS: One hundred fifty-nine patients met the inclusion criteria. The results noted that, for a 1◦ increase in PI-LL mismatch (preop and postop), the odds of developing ALD requiring surgery increased by 1.3 and 1.4 fold, respectively, which were statistically significant increases. Based on our analysis, a PI-LL mismatch of >11◦ had a positive predictive value of 75% for the development of symptomatic ALD requiring revision surgery.

CONCLUSIONS: A high PI-LL mismatch is strongly associated with the development of symptomatic ALD requiring revision lumbar spine surgery. The development of ALD may represent a global disease process as opposed to a focal condition. Spine surgeons may wish to consider assessment of spinopelvic parameters in the evaluation of degenerative lumbar spine pathology.


Benefit of Transforaminal Lumbar Interbody Fusion vs Posterolateral Spinal Fusion in Lumbar Spine Disorders


Neurosurgery 79:397–405, 2016

Despite increasing use and potential benefits of transforaminal lumbar interbody fusion (TLIF) compared with posterolateral spinal fusion (PSF), previous studies have not documented improved clinical outcomes with TLIF vs PSF.

OBJECTIVE: To compare the outcomes of TLIF with PSF in patients with spondylolisthesis, spinal stenosis, and adjacent level disease.

METHODS: The National Neurosurgical Quality and Outcomes Database was queried for patients who had a lumbar fusion. Eighty-five percent (1722) of enrolled cases had 12-month follow-up data. There were 306 PSF patients and 1230 TLIF patients. PSF cases within each diagnostic subgroup were propensity-matched to patients who had TLIF. Sufficient propensity-matched controls were available for patients with spondylolisthesis (109), spinal stenosis (63), and adjacent segment disease (47).

RESULTS: Operating room time, estimated blood loss, and length of stay were similar between PSF and TLIF in all 3 propensity-matched groups. In the spondylolisthesis group, there was a greater improvement in Oswestry Disability Index (ODI) with TLIF vs PSF at 3 months (19.4 vs 26.0, P = .009), 12 months (20.8 vs 29.3, P = .001), and in percentage reaching minimal clinically important difference at 12 months (80% vs 62%, P = .007). There were no differences in ODI improvement between PSF and TLIF in the stenosis or adjacent segment disease groups.

CONCLUSION: TLIF generated more favorable ODI outcomes than PSF for patients with spondylolisthesis, but not for patients with spinal stenosis or adjacent segment disease. There was also equivalence in operating room time and estimated blood loss between TLIF and PSF, potentially altering the long-standing assumption that PSF is a simpler procedure.

A Cost-Effectiveness Comparison Between Open Transforaminal and Minimally Invasive Lateral Lumbar Interbody Fusions

lateral lumbar interbody fusion

Neurosurgery 78:585–595, 2016

Direct cost comparisons between minimally invasive spine surgeries and the open options are rare.

OBJECTIVE: To compare healthcare costs associated with open transforaminal lumbar interbody fusion (TLIF) and minimally invasive lateral lumbar interbody fusion (LLIF) by calculating the incremental cost-effectiveness ratio (ICER) and to calculate the thresholds for minimum clinically important difference and minimum cost-effective difference for patient-reported outcome measures at the 2-year follow-up.

METHODS: Forty-five patients who underwent single-level TLIF and 29 patients who underwent single-level stand-alone LLIF were included in the comparison. All costs from diagnosis through the 2-year follow-up were available from a comprehensive single-center data bank within a unified hospital system. Payment provided for all spine-related medical resource use from the time of diagnosis through 2 years was recorded. A 0% discount rate was applied. Quality-adjusted life-years (QALYs) were calculated from the EuroQol-5D collected in an unbiased manner. Difference in total cost per QALY gained for LLIF minus that for TLIF was assessed as the estimate of the ICER from a US perspective.

RESULTS: Significant improvements were observed at the 2-year follow-up for both TLIF and LLIF with the Short Form-36 physical component summary, Oswestry Disability Index, visual analog scale back pain and leg pain scores, and EuroQol-5D. ICER calculations revealed similar mean cumulative QALYs gained at the 2-year interval (0.67 for TLIF and 0.60 for LLIF; P = .33). Median total costs of care after TLIF and LLIF were $44 068 and $45 574, respectively (P = .96). Minimum cost-effective difference thresholds with an anchor of ,$50 000 per QALY were higher than minimum clinically important difference thresholds for all patient-reported outcome measures. Total mean cost and EuroQol-5D were statistically equivalent between the 2 treatment groups.

CONCLUSION: TLIF and LLIF produced equivalent 2-year patient outcomes at an equivalent cost-effectiveness profile.

Surgical Outcomes for Minimally Invasive vs Open Transforaminal Lumbar Interbody Fusion


Neurosurgery 77:847–874, 2015

Minimally invasive transforaminal lumbar interbody fusion (TLIF)—or MI-TLIF—has been increasing in prevalence compared with open TLIF (O-TLIF) procedures. The use of MI-TLIF is an evolving technique with conflicting reports in the literature about outcomes.

OBJECTIVE: To investigate the impact of MI-TLIF in comparison with O-TLIF for early and late outcomes by using the Visual Analog Scale for back pain (VAS-back) and the Oswestry Disability Index (ODI). Secondary end points include blood loss, operative time, radiation exposure, length of stay, fusion rates, and complications between the 2 procedures.

METHODS: During August 2014, a systematic literature search was performed identifying 987 articles. Of these, 30 met inclusion criteria. A random-effects meta-analysis was performed by using both pooled and subset analyses based on study type.

RESULTS: Our meta-analysis demonstrated that MI-TLIF reduced blood loss (P < .001), length of stay (P < .001), and complications (P = .001) but increased radiation exposure (P < .001). No differences were found in fusion rate (P = .61) and operative time (P = .34). A decrease in late VAS-back scores was demonstrated for MI TLIF (P < .001), but no differences were found in early VAS-back, early ODI, and late ODI.

CONCLUSION: MI-TLIF is associated with reduced blood loss, decreased length of stay, decreased complication rates, and increased radiation exposure. The rates of fusion and operative time are similar between MI-TLIF and O-TLIF. Differences in long-term outcomes in MI-TLIF vs O-TLIF are inconclusive and require more research, particularly in the form of large, multi-institutional prospective randomized controlled trials.

Minimally invasive transforaminal lumbar interbody fusions and fluoroscopy

Minimally invasive transforaminal lumbar interbody fusions and fluoroscopy

Neurosurg Focus 35 (2):E8, 2013

There is an increasing awareness of radiation exposure to surgeons and the lifelong implications of such exposure. One of the main criticisms of minimally invasive transforaminal lumbar interbody fusion (MIS TLIF) is the amount of ionizing radiation required to perform the procedure. The goal in this study was to develop a protocol that would minimize the fluoroscopy time and radiation exposure needed to perform an MIS TLIF without compromising visualization of the anatomy or efficiency of the procedure.

Methods. A retrospective review of a prospectively collected database was performed to review the development of a low-dose protocol for MIS TLIFs in which a combination of low-dose pulsed fluoroscopy and digital spot images was used. Total fluoroscopy time and radiation dose were reviewed for 50 patients who underwent single-level MIS TLIFs.

Results. Fifty patients underwent single-level MIS TLIFs, resulting in the placement of 200 pedicle screws and 57 interbody spacers. There were 28 women and 22 men with an average age of 58.3 years (range 32–78 years). The mean body mass index was 26.2 kg/m2 (range 17.1–37.6 kg/m2). Indications for surgery included spondylolisthesis (32 patients), degenerative disc disease with radiculopathy (12 patients), and recurrent disc herniation (6 patients). Operative levels included 7 at L3–4, 40 at L4–5, and 3 at L5–S1. The mean operative time was 177 minutes (range 139–241 minutes). The mean fluoroscopic time was 18.72 seconds (range 7–29 seconds). The mean radiation dose was 0.247 mGy*m2 (range 0.06046–0.84054 mGy*m2). No revision surgery was required for any of the patients in this series.

Conclusions. Altering the fluoroscopic technique to low-dose pulse images or digital spot images can dramatically decrease fluoroscopy times and radiation doses in patients undergoing MIS TLIFs, without compromising image quality, accuracy of pedicle screw placement, or efficiency of the procedure.