Lateral Lumbar Interbody Fusion Surgery Research Articles

Impact of Osteoporosis on Short-Term Surgical Outcomes in Lumbar Degenerative Disease Patients Undergoing Lateral Lumbar Interbody Fusion: A Retrospective Analysis

This retrospective study assesses the influence of osteoporosis on the short-term clinical outcomes of lateral lumbar interbody fusion (LLIF) surgery in patients with lumbar degenerative diseases (LDD), focusing on complications, pain intensity, and quality of life improvements. The primary aim of this study is to investigate the impact of osteoporosis on the short-term clinical outcomes following LLIF surgery in LDD patients, with a particular focus on the incidence of cage subsidence (CS) and overall patient well-being postoperatively. A retrospective review was conducted on 73 patients who underwent LLIF for LDD. Patients were categorized into two groups based on osteoporosis status determined by dual-energy X-ray absorptiometry (DXA) scans: those with osteoporosis (n=20) and those without osteoporosis (n=53). Data collection included demographics, surgical details, complications, magnetic resonance imaging (MRI) analysis, pain intensity, and quality of life (Japanese Orthopaedic Association Back Pain Evaluation Questionnaire: JOABPEQ). The groups had no significant differences regarding operative time, estimated blood loss, and hospital stay duration. However, the incidence of CS was 40% in patients with osteoporosis, compared to 17% in non-osteoporotic patients. Despite this, significant improvements in spinal canal dimensions were observed in both groups. Both groups experienced significant reductions in pain intensity, with notable improvements in functional outcomes assessed by JOABPEQ, indicating the overall effectiveness of LLIF in enhancing patient well-being and functionality, irrespective of osteoporosis status. Osteoporosis increases the risk of CS in LLIF surgery for LDD patients but does not affect short-term pain relief and quality of life improvements.

Evaluating the Efficacy of IL-6 as Predictors of Lateral Lumbar Interbody Fusion Success: Insights From Pain Scores and JOABPEQ Assessments.

A prospective study. This study aims to explore the correlation between interleukin (IL)- 6 levels in intervertebral disc (IVD) tissue and clinical outcomes in patients undergoing lumbar surgery for lumbar degenerative disease (LDD). This prospective study analyzed 32 patients (22 men and 10 women, average age 69.6 years) who underwent lateral lumbar interbody fusion (LLIF). IL-6 gene expression in IVD tissues collected during surgery was measured and correlated with pre- and postoperative clinical outcomes, including pain intensity assessed via Numeric Rating Scales (NRS) and quality of life (QOL) evaluated through the Japanese Orthopaedic Association Back Pain Evaluation Questionnaire (JOABPEQ). IL-6 levels showed statistical correlations with postoperative intensity of low back pain (LBP) and several JOABPEQ domains. Patients with higher expression of IL-6 levels experienced more severe postoperative LBP and lower scores in lumbar function, walking ability, social life function, and mental health. The effectiveness rate of JOABPEQ scores was exceptionally high for low back pain (.548), walking ability (.677), and social functioning (.563), demonstrating the effectiveness of LLIF. The average operation time was 105.6 minutes, and the estimated blood loss was 85.6mL. The study underscores IL-6 as a potential biomarker for predicting surgical outcomes in LDD. High IL-6 levels correlate with worse postoperative LBP and lower QOL scores. Integrating molecular markers like IL-6 with patient-reported outcomes could provide a more comprehensive approach to postoperative care in spinal disorders, aiming to improve the overall QOL for LDD patients undergoing LLIF surgery.

Improved intervertebral fusion in LLIF rabbit model with a novel titanium cage

BACKGROUND CONTEXTThere is no established small animal approach model for the strict simulation of lateral lumbar interbody fusion (LLIF) surgery. PURPOSEThis study aims to establish a reliable LLIF rabbit model that strictly simulates the procedure and to preliminarily evaluate the differences in fusion outcomes with different graft materials. STUDY DESIGNA controlled laboratory. METHODSFifty-four 4-month-old white New Zealand female and male rabbits were selected and divided into five groups: Group A (dissection group) consisted of 9 rabbits, Group B (normal approach group) consisted of 9 rabbits, Group C (autogenous iliac bone group) consisted of 12 rabbits, Group D (BMP-2 carrier material group) consisted of 12 rabbits, and Group E (allograft bone group) consisted of 12 rabbits. Based on data from Group A, a novel titanium metal fusion device was designed. Postoperatively, at the 12-week mark, manual palpation was employed to compare the interbody fusion status among Groups B, C, D, and E. Specimens from Groups C, D, and E were subjected to Micro-CT scanning to compare various parameters such as trabecular bone volume (BV), bone volume fraction (BV/TV, BVF), and bone surface area (BS). Furthermore, a tissue histopathological examination was performed to observe the structure and morphology of newly formed bone within the fusion mass as well as the remodeling of the graft in each group. RESULTSBased on the measurements obtained from the dissection group, we designed a U-shaped interbody fusion device with dimensions of 10 mm in length, 2.5 mm in width, and 1.3 mm in height. In Group B, 9 cases exhibited intervertebral mobility. In Group C, 1 case showed nonfusion. In Group D, all cases achieved fusion. In Group E, 4 cases did not achieve fusion. Additionally, the Micro-CT results showed that the interbody fusion index scores were 4.64±0.50 in Group C, 4.33±0.65 in Group D, and 3.36±0.81 in Group E. There was no statistically significant difference in fusion index scores between Groups C and D (p=.853). Notably, Groups C and D had higher scores than Group E (p<.001). The trabecular bone volume (BV) in Groups C and D also showed no significant difference but was significantly higher than in Group E (p<.001). Furthermore, the histopathological results revealed that the specimens from Group E had less newly formed cartilage and bone compared to Groups C and D. CONCLUSIONSThis study successfully established a strict simulation of the clinical LLIF procedure in a rabbit model. Moreso, we conducted a preliminary validation indicating that the BMP-2 carrier material achieved interbody fusion outcomes similar to autogenous iliac bone. CLINICAL SIGNIFICANCEThe findings of this investigation from animal models provide a theoretical basis for the clinical use of BMP-2 to promote early spinal fusion in LLIF procedures. Importantly, the study provides a small animal model foundation for research related to LLIF surgery.

Vascular injury risk stratification for lateral lumbar interbody fusion (LLIF) at L4-L5: a morphometric study using magnetic resonance imaging.

Proper vascular injury risk stratification (VIRS) methods for L4-L5 lateral lumbar interbody fusion (LLIF) surgery have not been well-described. The objective of this study was to propose a novel VIRS method for L4-L5 LLIF surgery via the transpsoas approach. Axial magnetic resonance imaging (MRI) of adult patients were obtained and analyzed. The VIRS scores were assessed using anterior disc line to posterior vessel wall distance, the disc vessel angle (DVA), and the disc edge to vessel distance at the level of L4-L5 disc space. Ninety-one consecutive adult patients were included in the study. The right common iliac vein (CIV) had a high risk of injury with both right- and left-sided approaches. The left CIV had a moderate risk with a left-sided approach when the iliocaval confluence was above the L4-L5 disc space but had a high risk when the confluence was at the L4-L5 disc space. The left CIV had a high risk with a right-sided approach when the confluence was above the L4-L5 disc space but had a moderate risk when the confluence was at the L4-L5 disc space. The inferior vena cava (IVC) had a high risk with both right- and left-sided approaches. The aorta had a moderate risk regardless of the right or left-sided approaches. The left common iliac artery (CIA) had a moderate risk with a right-sided approach and a low risk with a left-sided approach. The right CIA had a low risk with both right- and left-sided approaches. There are significant vascular anatomic variations at the L4-L5 disc level and a proper VIRS can be performed utilizing a combination of anterior disc line to posterior vessel wall distance, DVA, and disc edge to vessel distance, on the axial MRI.

Comparison of Intraoperative Endplate Injury between Mini-Open Lateral Lumbar Interbody Fusion (LLIF) and Transforaminal Lumbar Interbody Fusion (TLIF) and Analysis of Risk Factors: A Retrospective Study

Objective The study aimed to compare the incidence of intraoperative endplate injury in patients who underwent Transforaminal interbody fusion (TLIF) and mini-open lumbar interbody fusion (LLIF) surgery. The independent risk factors related to endplate injury in LLIF procedure were analyzed. Methods A total of 199 patients who underwent LLIF (n = 106) or TLIF (n = 93) surgery from June 2019 to September 2021 were reviewed. The endplate injury was assessed by postoperative sagittal CT scan. A binary logistic analysis model were used to identify independent risk factors related to LLIF endplate injury based on univariate analysis. Results There was an obvious difference in the occurrence of intraoperative endplate injury between LLIF (42/106, 39.6%) and TLIF group (26/93, 28%), although it did not reach the significant level. L1 CT value (OR = 0.985, 95% CI = 0.972–0.998), cage position (OR = 3.881, 95% CI = 1.398–10.771) and height variance (OR = 1.263, 95% CI = 1.013–1.575) were independent risk factors for endplate injury in LLIF procedure. According to the cage settlement patterns, there 5 types of A to E. The severity of the facet joint degeneration was positively related to the occurrence of endplate injury. Conclusions The incidence of intraoperative endplate injury is higher in LLIF than in TLIF procedures. Low bone quantity, cage posterior position and larger height variance are risk factors to induce endplate injury in LLIF surgery. The facet joint degeneration may be related to severe endplate injuries and even fractures.

Incidence of postoperative neurological deficit with the use of an intraoperative neuromonitoring protocol for lateral lumbar interbody fusion.

Intraoperative neuromonitoring (IONM) has become commonplace in assessing neurological integrity during lateral approaches to lumbar interbody fusion surgeries. Neuromonitoring is designed to aid surgeons in identifying the potential for intraoperative nerve injury and reducing associated postoperative complications. However, standardized protocols for neuromonitoring have not been provided, and outcomes are not well described. The purpose of this study was to provide a standardized protocol for IONM, and to describe clinical outcomes in a cohort of individuals who underwent lateral lumbar interbody fusion (LLIF) surgery. A retrospective review of 169 consecutive patients who underwent LLIF surgery at a single institution from October 2014 to October 2016 was performed. Patient characteristics, intraoperative details, clinical outcomes, and postoperative deficits (PODs) were compared between patients who did and did not trigger IONM alerts, and between patients who did and did not demonstrate a POD. A protocol for IONM decision-making was generated based on these observations. Most patients (91.7%) underwent surgery for a degenerative spine condition. Twenty-three patients (13.6%) triggered neuromonitoring alerts, and 16 patients (9.5%) demonstrated a POD. Leg pain, back pain, and disability improved significantly (p < 0.045), and 2 patients had both motor and sensory deficits at the 12-week postoperative time point. Patients with a POD demonstrated greater operating room time (p = 0.034) and a greater number of interbody fusion levels (p = 0.015) but were less likely to have triggered a neuromonitoring alert (p = 0.04). There was no association between retractor time and POD (p = 0.98). When an IONM protocol was followed, individuals who experienced a POD were less likely to trigger an alert than those who did not experience a POD (p = 0.04). This study provides a protocol algorithm for IONM alert responses in patients undergoing LLIF surgery. PODs are most associated with multilevel fusion, and patients with alerts had a low rate of persistent deficit. Future research is needed to validate these findings using a more rigorous comparative study design.

The anatomical positioning change of retroperitoneal organs in prone and lateral position: an assessment for single-prone position lateral lumbar surgery.

There are reports that performing lateral lumbar interbody fusion (LLIF) in a prone, single position (single-prone LLIF) can be done safely in the prone position because the retroperitoneal organs reflect anteriorly with gravity. However, only a few study has investigated the safety of single-prone LLIF and retroperitoneal organ positioning in the prone position. We aimed to investigate the positioning of retroperitoneal organs in the prone position and evaluate the safety of single-prone LLIF surgery. A total of 94 patients were retrospectively reviewed. The anatomical positioning of the retroperitoneal organs was evaluated by CT in the preoperative supine and intraoperative prone position. The distances from the centre line of the intervertebral body to the organs including aorta, inferior vena cava, ascending and descending colons, and bilateral kidneys were measured for the lumbar spine. An "at risk" zone was defined as distance less than 10mm anterior from the centre line of the intervertebral body. Compared to supine preoperative CTs, bilateral kidneys at the L2/3 level as well as the bilateral colons at the L3/4 level had statistically significant ventral shift with prone positioning. The proportion of retroperitoneal organs within the at-risk zone ranged from 29.6 to 88.6% in the prone position. The retroperitoneal organs shifted ventrally with prone positioning. However, the amount of shift was not large enough to avoid risk for organ injuries and substantial proportion of patients had organs within the cage insertion corridor. Careful preoperative planning is warranted when considering single-prone LLIF.

Ureter position and risk of ureteral injury during lateral lumbar interbody fusion

BackgroundUreteral injury during lateral lumbar interbody fusion (LLIF) is uncommon. However, it is a serious complication that may require additional surgery should it occur. The objective of this study was to evaluate whether there was any change in the position of the left ureter between preoperative biphasic contrast-enhanced CT scanned in the supine position and intraoperative scanning in the right lateral decubitus position after stent placement, to assess the risk of ureteral injury in the actual surgical position. MethodsThe position of the left ureter scanned with the O-arm navigation system with the patient in the right lateral decubitus position and its position on preoperative biphasic contrast-enhanced CT images scanned with the patient in the supine position were investigated comparing their positions at the L2/3, L3/4, and L4/5 levels. ResultsThe ureter was located along the interbody cage insertion trajectory in 25 of 44 disc levels (56.8%) in the supine position, but in only 4 (9.5%) in the lateral decubitus position. The proportion of patients in whom the left ureter was located lateral to the vertebral body (along the LLIF cage insertion trajectory) at each level was 80% in the supine position and 15.4% in the lateral decubitus position at the L2/3 level, 53.3% in the supine position and 6.7% in the lateral decubitus position at the L3/4 level, and 33.3% in the supine position and 6.7% in the lateral decubitus position at the L4/5 level. ConclusionThe proportion of patients in whom the left ureter was located on the lateral surface of the vertebral body when the patient was in the actual surgical position (lateral decubitus position) was 15.4% at the L2/3 level, 6.7% at the L3/4 level, and 6.7% at the L4/5 level, suggesting that caution is required during LLIF surgery.

Single-Position Prone Lateral Lumbar Interbody Fusion Increases Operative Efficiency and Maintains Safety in Revision Lumbar Spinal Fusion.

Multi-centre retrospective cohort study. To evaluate the feasibility and safety of the single-position prone lateral lumbar interbody fusion (LLIF) technique for revision lumbar fusion surgery. Prone LLIF (P-LLIF) is a novel technique allowing for placement of a lateral interbody in the prone position and allowing posterior decompression and revision of posterior instrumentation without patient repositioning. This study examines perioperative outcomes and complications of single position P-LLIF against traditional Lateral LLIF (L-LLIF) technique with patient repositioning. A multi-centre retrospective cohort study involving patients undergoing 1 to 4 level LLIF surgery was performed at 4 institutions in the US and Australia. Patients were included if their surgery was performed via either: P-LLIF with revision posterior fusion; or L-LLIF with repositioning to prone. Demographics, perioperative outcomes, complications, and radiological outcomes were compared using independent samples t-tests and chi-squared analyses as appropriate with significance set at P <0.05. 101 patients undergoing revision LLIF surgery were included, of which 43 had P-LLIF and 58 had L-LLIF. Age, BMI and CCI were similar between groups. The number of posterior levels fused (2.21 P-LLIF vs. 2.66 L-LLIF, P =0.469) and number of LLIF levels (1.35 vs. 1.39, P =0.668) was similar between groups.Operative time was significantly less in the P-LLIF group (151 vs. 206 min, P =0.004). EBL was similar between groups (150mL P-LLIF vs. 182mL L-LLIF, P =0.31) and there was a trend toward reduced length of stay in the P-LLIF group (2.7 vs. 3.3d, P =0.09). No significant difference was demonstrated in complications between groups. Radiographic analysis demonstrated no significant differences in preoperative or postoperative sagittal alignment measurements. P-LLIF significantly improves operative efficiency when compared to L-LLIF for revision lumbar fusion. No increase in complications was demonstrated by P-LLIF or trade-offs in sagittal alignment restoration. Level 4.

The Analysis of Preoperative Roussouly Classification on Pain Scores and Radiological Data in Lateral Lumbar Interbody Fusion for Patients with Lumbar Degenerative Disease

A retrospective observational study. The type of sagittal profile defined by Roussouly has affected spinal degeneration and surgical outcome. This study aimed to investigate the effect of preoperative Roussouly classification on pain intensity and radiological data of lumbar degenerative disease (LDD) patients who underwent indirect decompression with lateral lumbar interbody fusion (LLIF). We retrospectively investigated 102 patients who underwent LLIF without direct decompression. Patients were subdivided into four groups according to the Roussouly classification determined from preoperative full-length and lateral spine X-rays, and classified according to Roussouly types I, II, and IV in the nonstandard group and Roussouly type III in the standard group. The nonstandard group showed improved sagittal vertical axis and lumbar lordosis after LLIF surgery, but the midsagittal canal diameter and axial central canal area of the thecal sac using T2-weighted sagittal and axial MRI were smaller than that in the standard group. On the other hand, each numeric rating scale (NRS) score one year after surgery improved in all patients. Changes in NRS scores in low back pain, leg pain, and numbness were not statistically significant between Roussouly classification types. These results suggest that the nonstandard group may have less indirect decompression effect from LLIF than the standard group. In the short term, we show for the first time after LLIF surgery that preoperative sagittal spinal alignment and the pelvic position may not significantly impact pain improvement.

Biomechanical Evaluation of Lateral Lumbar Interbody Fusion with Various Fixation Options for Adjacent Segment Degeneration: A Finite Element Analysis

Adjacent segment degeneration (ASD) is a common phenomenon after lumbar fusion. Lateral lumbar interbody fusion (LLIF) may provide an alternative treatment method for ASD. This study used finite element analysis to evaluate the biomechanical effects of LLIF with various fixation options and identify an optimal surgical strategy for ASD. A validated L1-S1 finite element model (FEM) was modified for simulation. Six FEMs of the lumbar spine were created and were divided into group 1 (L4-5 PLIF + L3-4 LLIF) and group 2 (L5-S1 PLIF + L4-5 LLIF). Each group consisted of a) cage-alone, b) cage + lateral screw fixation (LSF), and c) cage + bilateral pedicle screw fixation (BPSF) models. The range of motion (ROM), intradiscal pressure (IDP), and facet loads (FL) of adjacent segments as well as interbody cage stress were analyzed. The stress on the LLIF cage-superior endplate interface was highest in the cage-alone model followed by the cage + LSF model and cage + BPSF model. The increase in ROM, IDP, and FL at the adjacent segment was highest in the cage + BPSF model followed by the cage + LSF model and cage-alone model. However, the biomechanical effect on the adjacent segment seemed similar in the cage-alone and cage + LSF models. LLIF with BPSF is recommended when performing LLIF surgery for ASD after L4-5 and L5-S1 PLIF. Considering cage subsidence and biomechanical effect on the adjacent segment, LLIF with LSF may be a suboptimal option for ASD surgery.

Predictors and tactics for revision surgery in lateral lumbar interbody fusion

BackgroundThe purpose of this study is to analyze the factors affecting the revision of lateral lumbar interbody fusion (LLIF), and to summarize the complications and decision-making strategies for revision surgery after LLIF.MethodsWe retrospectively reviewed 21 cases suffered from a revision surgery after LLIF in our department from May 2017 to June 2020, with a mean follow-up of 14 months (12-25months). We collected X-ray plain films, CT (computed tomography), MRI (magnetic resonance imaging) and medical records of all patients undergoing LLIF surgery, then analyzed the reasons for revision and summarized the revision strategies in different situations. We analysed correlations between revision surgery and several factors, including age, body mass index (BMI), sex, bone quality, mode of internal fixation, spinal stenosis, postperative foraminal stenosis, disc height. Then we brought the different indicators into logistic regression to find out the risk factors of revision after LLIF. All these patients were evaluated by Quality-of-life outcomes. Univariate statistical analysis was performed using T-tests, Mann-Whitney U tests and Chi square tests.ResultsOf the 209 cases of LLIF, 21 patients underwent postoperative revision. All revision surgeries were successfully completed. The reasons for revision included vascular injury, unsatistactory implant placement, internal spinal instrumentation failure, cage migration, indirect decompression failure and infection. Indirect decompression failure was the most common indications for revision. Clinical status was apparently improved in ODI scores and VAS scores. Revision surgery did not impact long-term effect and satisfaction. Postoperative foraminal stenosis is a positive predictor for a revision surgical procedure.ConclusionPatients with postoperative foraminal stenosis are at higher risk of undergoing revision surgery after lateral lumbar interbody fusion. The correct choice of revision surgery can achieve satisfactory clinical results.

Treatment of Lumbar Degenerative Disease by Lateral Lumbar Interbody Fusion in Patients Under and Over 80 Years of Age

The purpose of this study was to compare clinical and radiological results of lateral lumbar interbody fusion (LLIF) for lumbar degenerative disease in patients under the age of 80years with those over the age of 80years. One hundred two patients who underwent LLIF without direct decompression were enrolled, including 92 patients who were less than 80years (group A) and 10 over 80years (group B). All patients were evaluated using numerical evaluation scale scores for low back pain, leg pain, and leg numbness, as well as demographic data, surgical data, and imaging data before and after LLIF surgery. Patients over the age of 80 years were found to have longer hospital stays (P= 0.006) and more postoperative muscle weakness (P= 0.011) and endplate injuries (P= 0.038). In addition, each numerical evaluation scale score improved significantly from preoperative to postoperative (P < 0.001). However, the changes in scores between preoperative and postoperative for each numerical evaluation scale were not significantly different between the 2 groups. Statistically significant increases in lumbar lordosis preoperatively compared with postoperatively were observed in patients under 80years but did not change in those over 80years. These data suggest a need for awareness of intraoperative endplate injury and postoperative motor weakness. Critically, indirect decompression with LLIF in lumbar degenerative disease in patients over age 80 as well as those under age 80 has shown satisfactory clinical and radiological results. This study shows that age alone should not prevent older people from undergoing LLIF.

225. Comparison of single position prone lateral lumbar interbody fusion and lateral lumbar interbody fusion with repositioning in revision lumbar spinal fusion

<h3>BACKGROUND CONTEXT</h3> Prone LLIF (P-LLIF) is a novel technique allowing for placement of a lateral interbody in the prone position and allowing posterior decompression and revision of posterior instrumentation without repositioning. To date, studies evaluating the P-LLIF have been small single surgeon series. This multicentre retrospective cohort examines perioperative outcomes and complications of single position P-LLIF againsttraditional Lateral LLIF (L-LLIF) technique with patient repositioning in patients undergoing revision lumbar fusion surgery. <h3>PURPOSE</h3> To evaluate the feasibility and safety of the single-position P-LLIF technique for revision lumbar fusion surgery. <h3>STUDY DESIGN/SETTING</h3> Multicenter retrospective cohort study. <h3>PATIENT SAMPLE</h3> A total of 101 patients undergoing revision circumferential fusion with lateral lumbar interbody fusion (LLIF) were included, of which 43 had P-LLIF and 58 had L-LLIF. <h3>OUTCOME MEASURES</h3> Outcome measures included levels fused, operative time, estimated blood loss and perioperative complications. Radiographic analysis included lumbar lordosis (LL), pelvic incidence (PI), pelvic tilt (PT), PI-LL mismatch and segmental lumbar lordosis. <h3>METHODS</h3> A multicenter retrospective cohort study was performed from 4 institutions from the USA and Australia of patients undergoing revision anterior-posterior lumbar fusion via either: 1) single-position prone LLIF (P-LLIF); or 2) lateral decubitus LLIF with repositioning to prone (L-LLIF) between January 2015 and November 2021. Patients with greater than 4 levels fused were excluded. Demographics, perioperative outcomes, complications and radiological outcomes were compared using independent samples t-tests and chi-squared analyses as appropriate with significance set at p<0.05. <h3>RESULTS</h3> A total of 101 patients undergoing revision lateral lumbar interbody fusion surgery were included, of which 43 had P-LLIF and 58 had L-LLIF. Age, BMI and CCI were similar between groups. The number of posterior levels fused (2.21 P-LLIF vs 2.66 L-LLIF, p=0.469) and interbody levels fused (1.23 P-LLIF vs 1.25 L-LLIF, p=0.838) were similar between groups. Levels decompressed, posterior column osteotomy and anterior column release were similar between groups. Operative time was significantly less in the P-LLIF group compared to the L-LLIF group (151 vs 206 min, p=0.004). EBL was similar between groups (150 mL P-LLIF vs 182 mL L-LLIF, p=0.31) and there was a trend toward reduced length of stay (2.7 vs 3.3 days, p=0.09). No significant difference was demonstrated in perioperative or postoperative complications between P-LLIF and L-LLIF groups. Radiographic analysis demonstrated no significant differences in preoperative or postoperative sagittal alignment as measured by lumbar lordosis, PI-LL mismatch, or segmental lumbar lordosis between groups. <h3>CONCLUSIONS</h3> P-LLIF significantly improves operative efficiency and may reduce length of stay when compared to L-LLIF and repositioning for revision lumbar fusion. No increase in complications was demonstrated by P-LLIF or trade-offs in sagittal alignment restoration. <h3>FDA DEVICE/DRUG STATUS</h3> This abstract does not discuss or include any applicable devices or drugs.

Rates of Postoperative Complications and Approach-related Neurological Symptoms After L4-L5 Lateral Transpsoas Lumbar Interbody Fusion Compared With Upper Lumbar Levels.

This was a retrospective comparative study. To compare the likelihood of approach-related complications for patients undergoing single-level lateral lumbar interbody fusion (LLIF) at L4-L5 to those undergoing the procedure at upper lumbar levels. LLIF has been associated with a number of advantages when compared with traditional interbody fusion techniques. However, potential risks with the approach include vascular or visceral injury, thigh dysesthesias, and lumbar plexus injury. There are concerns of a higher risk of these complications at the L4-L5 level compared with upper lumbar levels. A retrospective cohort review was completed for consecutive patients undergoing single-level LLIF between 2004 and 2019 by a single surgeon. Indication for surgery was symptomatic degenerative lumbar stenosis and/or spondylolisthesis. Patients were divided into 2 cohorts: LLIF at L4-L5 versus a single level between L1 and L4. Baseline characteristics, intraoperative complications, postoperative approach-related neurological symptoms, and patient-reported outcomes were compared and analyzed between the cohorts. A total of 122 were included in analysis, of which 58 underwent LLIF at L4-L5 and 64 underwent LLIF between L1 and L4. There were no visceral or vascular injuries or lumbar plexus injuries in either cohort. There was no significant difference in the rate of postoperative hip pain, anterior thigh dysesthesias, and/or hip flexor weakness between the cohorts (53.5% L4-L5 vs. 37.5% L1-L4; P =0.102). All patients reported complete resolution of these symptoms by 6-month postoperative follow-up. LLIF surgery at the L4-L5 level is associated with a similar infrequent likelihood of approach-related complications and postoperative hip pain, thigh dysesthesias, and hip flexor weakness when compared with upper lumbar level LLIF. Careful patient selection, meticulous use of real-time neuromonitoring, and an understanding of the anatomic location of the lumbar plexus to the working corridor are critical to success.

Predictive parameters for successful indirect decompression of the lateral lumbar interbody fusion (LLIF) surgery

BackgroundPreoperative radiographic parameters in selecting the best surgical candidates for indirect decompression in the lateral lumbar interbody fusion (LLIF) surgery is considered one of the important concerns; there is a paucity of literature concerning this topic. This study aimed to find preoperative radiographic parameters that correlate with successful indirect decompression. MethodsWe retrospectively reviewed patients who underwent LLIF surgery for various degenerative spine diseases at our institute. All patients included in the study had completed radiographs with preoperative and postoperative magnetic resonance imaging (MRI) within 3 months after surgery. Patients were categorized into success and failed indirect decompression using the cross-sectional area for pre and postoperative MRI scans. Various parameters were used to find an association for successful indirect decompression. ResultsSixty patients were included in our study with a total of 77 levels. Over two-thirds of patients (41/60, 68.3%) underwent oblique lateral lumbar interbody fusion or extreme lateral lumbar interbody fusion with posterior screw fixation. Of the 77 levels for which LLIF was performed, successful indirect decompression was attained in 38 levels and failed indirect decompression in 39 levels (49.3% success rate). Five parameters were significantly different between the success group and failed group. Only the cross-sectional area of the thecal sac (CSA) was significantly different as determined by a binary logistic mixed-effect regression model. Adding cut-point value to ROC curve of CSA, if CSA ≤ 106.97 mm2, it resulted in 82.14% sensitivity, and 72.41% specificity. ConclusionLLIF showed significant improvement in average postoperative parameters. However, the cross-sectional area of the thecal sac (CSA) was the only parameter that inversely correlated with successful indirect decompression with LLIF. We concluded that even patients with severe spinal canal stenosis are good candidates for LLIF surgery owing to its indirect decompression.

Effect of the In Situ Screw Implantation Region and Angle on the Stability of Lateral Lumbar Interbody Fusion: A Finite Element Study.

ObjectiveTo investigate the effect of the in situ screw implantation region and angle on the stability of lateral lumbar interbody fusion (LLIF) from a biomechanical perspective.MethodsA validated L2‐4 finite element (FE) model was modified for simulation. The L3‐4 fused segment undergoing LLIF surgery was modeled. The area between the superior and inferior edges and the anterior and posterior edges of the vertebral body (VB) is divided into four zones by three parallel lines in coronal and horizontal planes. In situ screw implantation methods with different angles based on the three parallel lines in coronal plane were applied in Models A, B, and C (A: parallel to inferior line; B: from inferior line to midline; C: from inferior line to superior line). In addition, four implantation methods with different regions based on the three parallel lines in horizontal plane were simulated as types 1–2, 1–3, 2–2, and 2–3 (1–2: from anterior line to midline; 1–3: from anterior line to posterior line; 2–2: parallel to midline; 2–3: from midline to posterior line). L3‐4 ROM, interbody cage stress, screw‐bone interface stress, and L4 superior endplate stress were tracked and calculated for comparisons among these models.ResultsThe L3‐4 ROM of Models A, B, and C decreased with the extent ranging from 47.9% (flexion‐extension) to 62.4% (lateral bending) with no significant differences under any loading condition. Types 2–2 and 2–3 had 45% restriction, while types 1–2 and 1–3 had 51% restriction in ROM under flexion‐extension conditions. Under lateral bending, types 2–2 and 2–3 had 70.6% restriction, while types 1–2 and 1–3 had 61.2% restriction in ROM. Under axial rotation, types 2–2 and 2–3 had 65.2% restriction, while types 1–2 and 1–3 had 59.3% restriction in ROM. The stress of the cage in types 2–2 and 2–3 was approximately 20% lower than that in types 1–2 and 1–3 under all loading conditions in all models. The peak stresses at the screw‐bone interface in types 2–2 and 2–3 were much lower (approximately 35%) than those in types 1–2 and 1–3 under lateral bending, while no significant differences were observed under flexion‐extension and axial rotation. The peak stress on the L4 superior endplate was approximately 30 MPa and was not significantly different in all models under any loading condition.ConclusionsDifferent regions of entry‐exit screws induced multiple screw trajectories and influenced the stability and mechanical responses. However, different implantation angles did not. Considering the difficulty of implantation, the ipsilateral‐contralateral trajectory in the lateral middle region of the VB can be optimal for in situ screw implantation in LLIF surgery.

The Effect of Preoperative Neuropathic Pain and Nociceptive Pain on Postoperative Pain Intensity in Patients with the Lumbar Degenerative Disease Following Lateral Lumbar Interbody Fusion

The purpose of this study was to analyze whether the type of preoperative pain affects the improvement in postoperative pain intensity in patients with a lumbar degenerative disease (LDD). We retrospectively reviewed 93 patients who underwent lateral lumbar interbody fusion (LLIF) without direct decompression. All patients were evaluated using Numeric Rating Scale (NRS) scores for low back pain (NRSLBP), leg pain (NRSLP), and leg numbness (NRSLN) and imaging data before and after LLIF surgery. Based on the Japanese version of the painDETECT scores, patients were classified into 3 groups: a neuropathic pain (NeP) group, a nociceptive pain (NocP) group, and an intermediate mixed pain group. The Japanese version of the painDETECT identified NeP in 20.4% of patients with LDD prior to LLIF. Preoperative NRSLBP, NRSLP, and NRSLN scores were higher in the NeP group than those in the NocP group. All types of pain improved after LLIF surgery. The NRSLBP score 12months after surgery was higher in the NeP group (3.8±2.8) than that in the NocP group (1.9±2.2) (P=0.008). Similar results were obtained with NRSLP (NeP group= 3.1±2.8, NocP group= 1.5±2.0, P=0.010). Although LLIF was useful for relieving all types of preoperative pain in LDD patients, the NRS scores for preoperative pain were higher in the NeP group than those in the NocP group, and the postoperative NRSLBP and NRSLP score was significantly higher in the NeP group. Thus, controlling preoperative NeP may improve therapeutic efficacy.

Do evoked potentials matter? Pre-pathologic signal change and clinical outcomes with expandable cages in lateral lumbar interbody fusion surgery

Minimally Invasive Lateral Lumbar Interbody Fusion (MIS LLIF) is a reliable technique for treatment of degenerative disk disease, foraminal stenosis and spinal deformity. The retroperitoneal transpsoas approach risks lumbar plexus injury that may result in anterior thigh pain, sensory loss and weakness. A prospective study of 64 consecutive patients undergoing MIS LLIF with expandable cages (23 standalone, 41 integrated with lateral plate) using multimodal electrophysiological monitoring was performed. We measured sequential retraction times, complications, patient reported outcome scores and electrophysiologic findings with a minimum 12-month follow-up. Incidence of evoked potential and electromyographic signal change was moderate, and rarely resulted in post-operative neurologic deficit. Evoked potential signal changes were frequently resolved by the un-breaking of the surgical table or repositioning of the retractor. Average retraction times were 24 (15–41) minutes for standalone cages and 30 (15–41) minutes for integrated cages. At follow-up, the vast majority (97%) of patients reported significant clinical improvement post-operatively with only 2 patients reporting postoperative neurologic symptoms and subsequent recovery at 12-months. The present study shows that evoked potentials combined with electromyography is a more sensitive measure of pre-pathologic lumbar plexopathy in LLIF compared to electromyography alone, especially at L3/4 and L4/5 levels. Based on our findings, there is limited clinical indication for routine neural monitoring at rostral lumbar levels. The routine inclusion of multimodal electrophysiological monitoring in lateral transpsoas surgery is recommended to minimise the risk of neural injury by enabling optimal patient and retractor positioning and continued surveillance throughout the procedure.

Effects of preoperative sagittal spinal imbalance on pain after lateral lumbar interbody fusion

Sagittal misalignment has been associated with negative quality of life (QOL). However, there is no report on whether differences in preoperative sagittal misalignment in patients with lumbar degenerative diseases affect postoperative results after lateral lumbar interbody fusion (LLIF). We investigated whether preoperative sagittal alignment influences the correction of alignment after surgery and whether the preoperative sagittal alignment affects the rating of low back pain, leg pain, and leg numbness. The subjects were 81 patients (48 male, 33 females, average age at surgery 70.2 years) who underwent anterior–posterior combined surgery with LLIF and percutaneous pedicle screws from May 2018 to July 2020. Cluster analysis was performed using the preoperative sagittal vertical axis (SVA) value, and patients were classified into two groups (group 1; n = 30, SVA = 129.0 ± 53.4 mm, group 2; n = 51, SVA = 30.8 ± 23.5 mm). Baseline demographics and treatment data were compared between groups. Sagittal and pelvic parameters and pain scores, such as low back pain, leg pain, and leg numbness, were also compared. Operative time, blood loss, and length of hospital stay did not differ significantly between groups. The changes (Δ) in SVA and lumbar lordosis (LL) for all patients from before to after surgery were not significant (ΔSVA; p = 0.218, ΔLL; p = 0.189, respectively). The SVA, LL, and PI − LL changed significantly after the surgery in group 1, but no marked improvement in sagittal imbalance was obtained after LLIF surgery. The improvement in each pain score from before to after the surgery did not differ significantly between groups. LLIF surgery has a limited chance of recovering sagittal imbalance. However, postoperative low back pain, leg pain, and leg numbness may be improved by LLIF surgery, regardless of the preoperative sagittal alignment.