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.

Complications of the Prone Transpsoas Lateral Lumbar Interbody Fusion for Degenerative Lumbar Spine Disease: A Multicenter Study

Neurosurgery 93:1106–1111, 2023

The prone transpsoas (PTP) approach for lateral lumbar interbody fusion (LLIF) is a novel technique for degenerative lumbar spine disease. However, there is a paucity of information in the literature on the complications of this procedure, with all published data consisting of small samples. We aimed to report the intraoperative and postoperative complications of PTP in the largest study to date.

METHODS: A retrospective electronic medical record review was conducted at 11 centers to identify consecutive patients who underwent LLIF through the PTP approach between January 1, 2021, and December 31, 2021. The following data were collected: intraoperative characteristics (operative time, estimated blood loss [EBL], intraoperative complications [anterior longitudinal ligament (ALL) rupture, cage subsidence, vascular and visceral injuries]), postoperative complications, and hospital stay.

RESULTS: A total of 365 patients were included in the study. Among these patients, 2.2% had ALL rupture, 0.3% had cage subsidence, 0.3% had a vascular injury, 0.3% had a ureteric injury, and no other visceral injuries were reported. Mean operative time was 226.2 ± 147.9 minutes. Mean EBL was 138.4 ± 215.6 mL. Mean hospital stay was 2.7 ± 2.2 days. Postoperative complications included new sensory symptoms—8.2%, new lower extremity weakness—5.8%, wound infection—1.4%, cage subsidence—0.8%, psoas hematoma—0.5%, small bowel obstruction and ischemia—0.3%, and 90-day readmission—1.9%.

CONCLUSION: In this multicenter case series, the PTP approach was well tolerated and associated with a satisfactory safety profile.

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.

Anterolateral versus posterior minimally invasive lumbar interbody fusion surgery for spondylolisthesis: comparison of outcomes from a global, multicenter study at 12-months follow-up

The Spine Journal 23 (2023) 1494−1505

Several minimally invasive lumbar interbody fusion techniques may be used as a treatment for spondylolisthesis to alleviate back and leg pain, improve function and provide stability to the spine. Surgeons may choose an anterolateral or posterior approach for the surgery however, there remains a lack of real-world evidence from comparative, prospective studies on effectiveness and safety with relatively large, geographically diverse samples and involving multiple surgical approaches.

PURPOSE: To test the hypothesis that anterolateral and posterior minimally invasive approaches are equally effective in treating patients with spondylolisthesis affecting one or two segments at 3months follow-up and to report and compare patient reported outcomes and safety profiles between patients at 12-months post-surgery.

DESIGN: Prospective, multicenter, international, observational cohort study.

PATIENT SAMPLE: Patients with degenerative or isthmic spondylolisthesis who underwent 1- or 2-level minimally invasive lumbar interbody fusion.

OUTCOME MEASURES: Patient reported outcomes assessing disability (ODI), back pain (VAS), leg pain (VAS) and quality of life (EuroQol 5D-3L) at 4-weeks, 3-months and 12-months follow-up; adverse events up to 12-months; and fusion status at 12-months post-surgery using X-ray and/or CT-scan. The primary study outcome is improvement in ODI score at 3-months. METHODS: Eligible patients from 26 sites across Europe, Latin America and Asia were consecutively enrolled. Surgeons with experience in minimally invasive lumbar interbody fusion procedures used, according to clinical judgement, either an anterolateral (ie, ALIF, DLIF, OLIF) or posterior (MIDLF, PLIF, TLIF) approach. Mean improvement in disability (ODI) was compared between groups using ANCOVA with baseline ODI score used as a covariate. Paired t-tests were used to examine change from baseline in PRO for both surgical approaches at each timepoint after surgery. A secondary ANCOVA using a propensity score as a covariate was used to test the robustness of conclusions drawn from the between group comparison.

RESULTS: Participants receiving an anterolateral approach (n=114) compared to those receiving a posterior approach (n=112) were younger (56.9 vs 62.0 years, p <.001), more likely to be employed (49.1% vs 25.0%, p<.001), have isthmic spondylolisthesis (38.6% vs 16.1%, p<.001) and less likely to only have central or lateral recess stenosis (44.9% vs 68.4%, p=.004). There were no statistically significant differences between the groups for gender, BMI, tobacco use, duration of conservative care, grade of spondylolisthesis, or the presence of stenosis. At 3-months follow-up there was no difference in the amount of improvement in ODI between the anterolateral and posterior groups (23.2 § 21.3 vs 25.8 § 19.5, p=.521). There were no clinically meaningful differences between the groups on mean improvement for back- and leg-pain, disability, or quality of life until the 12-months follow-up. Fusion rates of those assessed (n=158; 70% of the sample), were equivalent between groups (anterolateral, 72/88 [81.8%] fused vs posterior, 61/70 [87.1%] fused; p=.390).

CONCLUSIONS: Patients with degenerative lumbar disease and spondylolisthesis who underwent minimally invasive lumbar interbody fusion presented statistically significant and clinically meaningful improvements from baseline up to 12-months follow-up. There were no clinically relevant differences between patients operated on using an anterolateral or posterior approach.

Complications associated with single-position prone lateral lumbar interbody fusion

J Neurosurg Spine 39:380–386, 2023

Lateral lumbar interbody fusion (LLIF) is a workhorse surgical approach for lumbar arthrodesis. There is growing interest in techniques for performing single-position surgery in which LLIF and pedicle screw fixation are performed with the patient in the prone position. Most studies of prone LLIF are of poor quality and without long-term followup; therefore, the complication profile related to this novel approach is not well known. The objective of this study was to perform a systematic review and pooled analysis to understand the safety profile of prone LLIF.

METHODS A systematic review of the literature and a pooled analysis were conducted according to the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines. All studies reporting prone LLIF were assessed for inclusion. Studies not reporting complication rates were excluded.

RESULTS Ten studies meeting the inclusion criteria were analyzed. Overall, 286 patients were treated with prone LLIF across these studies, and a mean (SD) of 1.3 (0.2) levels per patient were treated. The 18 intraoperative complications reported included cage subsidence (3.8% [3/78]), anterior longitudinal ligament rupture (2.3% [5/215]), cage repositioning (2.1% [2/95]), segmental artery injury (2.0% [5/244]), aborted prone interbody placement (0.8% [2/244]), and durotomy (0.6% [1/156]). No major vascular or peritoneal injuries were reported. Sixty-eight postoperative complications occurred, including hip flexor weakness (17.8% [21/118]), thigh and groin sensory symptoms (13.3% [31/233]), revision surgery (3.8% [3/78]), wound infection (1.9% [3/156]), psoas hematoma (1.3% [2/156]), and motor neural injury (1.2% [2/166]).

CONCLUSIONS Single-position LLIF in the prone position appears to be a safe surgical approach with a low complication profile. Longer-term follow-up and prospective studies are needed to better characterize the long-term complication rates related to this approach.

Far lateral lumbar interbody fusion with unilateral pedicle screw fixation and double traversing cages using a biportal endoscopic technique

Acta Neurochirurgica (2023) 165:2165–2169

Transforaminal lumbar interbody fusion (TLIF) with a single cage and bilateral pedicle screw fixation results in decreased stability or increased risk of cage displacement Wang and Guo (Comput Methods Biomech Biomed Eng, 24(3):308–319, 6). We succeeded in inserting double traversing cages with unilateral pedicle screw fixation (UPSF) during far lateral TLIF using unilateral biportal endoscopy (UBE).

Method We attempted far lateral UBE-TLIF through two small incisions for degenerative lumbar spondylolisthesis with unilateral stenosis. With the help of novel instruments, far lateral UBE-TLIF with double traversing cages and UPSF was performed under tracheal intubation anaesthesia.

Conclusions We successfully performed far lateral UBE-TLIF with double traversing cages and UPSF. This procedure may be an alternative minimally invasive method for treating lumbar instability.

Anterior-To-Psoas Approach Measurements, Feasibility, Non-Neurological Structures at Risk and Influencing Factors: A Bilateral Analysis From L1-L5 Using Computed Tomography Imaging

Operative Neurosurgery 25:52–58, 2023

Spinal fusion through the anterior-to-psoas (ATP) technique harbors several approach-related risks. We used abdominal computed tomography imaging to analyze the L1-L5 ATP fusion approach measurements, feasibility, degree of obstruction by non-neurological structures, and the influence of patient characteristics on ATP approach dimensions.

METHODS: The vascular window, psoas window, safe window, and incision line anterior and posterior margins for the ATP approach were measured on abdominal computed tomography imaging. The feasibility of approach and the presence of kidneys, ribs, liver, spleen, and iliac crests within the ATP approach were also measured. Correlation and regression models among radiographic measurements and patient age, height, weight, and body mass index (BMI) were analyzed as well as differences in approach measurements based on sex.

RESULTS: Safe window and incision line measurements were more accommodating for the left-sided vs right-sided ATP approach. At L4-5, the ATP approach was not feasible 18% of the time on the left side vs 60% of the time on the right side. The spleen was present 22%, 10%, and 3% of the time from L1-4, while the liver was present 56%, 30%, and 9% of the time. The iliac crests were not observed within ATP parameters. Patient age, height, weight, and BMI did not strongly correlate with approach measurements, although ATP dimensions did differ based on sex.

CONCLUSION: This study reports characteristics of the ATP approach including approach measurements, feasibility, non-neurological structures at risk, and influencing factors to approach measurements. While incision line measurements are larger for male patients compared with female patients at the lower lumbar levels, safe window sizes are similar across all levels L1-L5. The kidneys, ribs, spleen, and liver are potential at-risk structures during the ATP approach, although the iliac crests pose limited concern for ATP technique. Patient characteristics such as age, height, weight, and BMI do not markedly affect ATP approach considerations.

Long-Term Durability of Stand-Alone Lateral Lumbar Interbody Fusion

Neurosurgery 93:60–65, 2023

BACKGROUND: The long-term durability of stand-alone lateral lumbar interbody fusion (LLIF) remains unknown.

OBJECTIVE: To evaluate whether early patient-reported outcome measures after stand-alone LLIF are sustained on long-term follow-up.

METHODS: One hundred and twenty-six patients who underwent stand-alone LLIF between 2009 and 2017 were included in this study. Patient-reported outcome measures included the Oswestry Disability Index (ODI), EuroQOL-5D (EQ-5D), and visual analog score (VAS) scores. Durable outcomes were defined as scores showing a significant improvement between preoperative and 6-week scores without demonstrating any significant decline at future time points. A repeated measures analysis was conducted using generalized estimating equations (model) to assess the outcome across different postoperative time points, including 6 weeks, 1 year, 2 years, and 5 years.

RESULTS: ODI scores showed durable improvement at 5-year follow-up, with scores improving from 46.9 to 38.5 (P = .001). Improvements in EQ-5D showed similar durability up to 5 years, improving from 0.48 to 0.65 (P = .03). VAS scores also demonstrated significant improvements postoperatively that were durable at 2-year follow-up, improving from 7.0 to 4.6 (P < .0001).

CONCLUSION: Patients undergoing stand-alone LLIF were found to have significant improvements in ODI and EQ-5D at 6week follow-up that remained durable up to 5 years postoperatively. VAS scores were found to be significantly improved at 6 weeks and up to 2 years postoperatively but failed to reach significance at 5 years. These findings demonstrate that patients undergoing stand-alone LLIF show significant improvement in overall disability after surgery that remains durable at long-term follow-up.

Factors associated with readmission after minimally invasive transforaminal lumbar interbody fusion

J Neurosurg Spine 38:681–687, 2023

The objective of this study was to identify factors that lead to a prolonged hospital stay or 30-day readmission after minimally invasive surgery (MIS) for transforaminal lumbar interbody fusion (TLIF) at a single institution.

METHODS Consecutive patients who underwent MIS TLIF from January 1, 2016, to March 31, 2018, were retrospectively analyzed. Demographic data, including age, sex, ethnicity, smoking status, and body mass index, were collected along with operative details, indications, affected spinal levels, estimated blood loss, and operative duration. The effects of these data were evaluated relative to the hospital length of stay (LOS) and 30-day readmission.

RESULTS The authors identified 174 consecutive patients who underwent MIS TLIF at 1 or 2 levels from a prospectively collected database. The mean (range) patient age was 64.1 (31–81) years, 97 were women (56%), and 77 were men (44%). Of 182 levels fused, 127 were done at L4–5 (70%), 32 at L3–4 (18%), 13 at L5–S1 (7%), and 10 at L2–3 (5%). Patients underwent 166 (95%) single-level procedures and 8 (5%) 2-level procedures. The mean (range) procedural duration, defined as the time from incision to closure, was 164.6 (90–529) minutes. The mean (range) LOS was 1.8 (0–8) days. Eleven patients (6%) were readmitted within 30 days; the most frequent causes were urinary retention, constipation, and persistent or contralateral symptoms. Seventeen patients had LOS greater than 3 days. Six of those patients (35%) were identified as widows, widowers, or divorced, and 5 of them lived alone. Six patients with prolonged LOS (35%) required placement in either skilled nursing or acute inpatient rehabilitation. Regression analyses showed living alone (p = 0.04) and diabetes (p = 0.04) as predictors of readmission. Regression analyses revealed female sex (p = 0.03), diabetes (p = 0.03), and multilevel surgery (p = 0.006) as predictors of LOS > 3 days.

CONCLUSIONS Urinary retention, constipation, and persistent radicular symptoms were the leading causes of readmission within 30 days of surgery in this series, which is distinct from data from the American College of Surgeons National Surgical Quality Improvement Program. The inability to discharge a patient home for social reasons led to prolonged inpatient hospital stays. Identifying these risk factors and proactively addressing them could lower readmission rates and decrease LOS among patients undergoing MIS TLIF.

Technique for Validation of Intraoperative Navigation in Minimally Invasive Spine Surgery

Operative Neurosurgery 24:451–454, 2023

Intraoperative 3-dimensional navigation is an enabling technology that has quickly become a commonplace in minimally invasive spine surgery (MISS). It provides a useful adjunct for percutaneous pedicle screw fixation. Although navigation is associated with many benefits, including improvement in overall screw accuracy, navigation errors can lead to misplaced instrumentation and potential complications or revision surgery. It is difficult to confirm navigation accuracy without a distant reference point.

OBJECTIVE: To describe a simple technique for validating navigation accuracy in the operating room during MISS.

METHODS: The operating room is set up in a standard fashion for MISS with intraoperative cross-sectional imaging available. A 16-gauge needle is placed within the bone of the spinous process before intraoperative cross-sectional imaging. The entry level is chosen such that the space between the reference array and the needle encompasses the surgical construct. Before placing each pedicle screw, accuracy is verified by placing the navigation probe over the needle.

RESULTS: This technique has identified navigation inaccuracy and led to repeat crosssectional imaging. No screws have been misplaced in the senior author’s cases since adopting this technique, and there have been no complications attributable to the technique.

CONCLUSION: Navigation inaccuracy is an inherent risk in MISS, but the described technique may mitigate this risk by providing a stable reference point.