Transpsoas Lateral Lumbar Interbody Fusion Research Articles

Clinical and radiographic outcomes following 120 consecutive patients undergoing prone transpsoas lateral lumbar interbody fusion

Clinical and radiographic outcomes following 120 consecutive patients undergoing prone transpsoas lateral lumbar interbody fusion

Single Position Lateral versus Prone Transpsoas Lateral Interbody Fusion Inclusive of L4-L5: A Single Surgeon Experience Examining Early Postoperative Outcomes

The transpsoas lateral lumbar interbody fusion (LLIF) procedure is a minimally invasive lumbar spine approach that provides indirect neural decompression, improved sagittal alignment, and a high fusion rate. Typically accompanied by posterior pedicle screw insertion, there has been interest in performing LLIF in a single position to decrease cost and time under anesthesia. However, there is a paucity of direct comparisons between single-position LLIF via prone versus lateral decubitus positioning. Therefore, this stud aims to compare the outcomes of a single surgeon performing prone versus lateral single-position LLIF, inclusive of the L4-L5 level. A retrospective review was performed of a consecutive case series of patients who underwent either prone or lateral, single-position LLIF by a single surgeon All cases involved the L4-L5 level. Demographic data, perioperative details, clinical outcomes, and pre- and postoperative lumbar lordosis were recorded. 63 patients underwent lateral, and 16 patients underwent prone single-position LLIF. Demographics and average interbody size were similar between groups. Operative time, change in lumbar lordosis, and length of hospital stay did not differ between the two positions. Both groups performed similarly in terms of pre- and postoperative VAS pain score, and complications. Patients who underwent lateral position LLIF ambulated farther on postoperative day 1 (250 vs. 200 feet, p=0.015). Average time to follow up was 53 weeks. This study demonstrates promising preliminary results indicating that single-position LLIF performs well, even at the L4-L5 level, in both the prone and lateral positions.

Minimally Invasive L4-5 Oblique Lumbar Interbody Fusion With Robot-Assisted Single-Position Posterior Fixation: 2-Dimensional Operative Video.

We present here a 58-year-old female patient with L4-5 spondylolisthesis, who underwent a minimally invasive L4-5 oblique lumbar interbody fusion (OLIF) with robot-assisted bilateral posterior instrumented fixation in a single lateral position (Mazor X Stealth Edition, Medtronic). There has been interest in detailed video-based descriptions of single-position surgery with lateral approach interbody fusions, either in the prone or lateral decubitus position.1-6 Particularly, the addition of robotics has been shown to help increase overall operating efficiency in the lateral position with reduced case times even with the increased up-front robot setup time.7,8 The OLIF, also known as an anterior-to-psoas approach, allows for single-position posterior fixation and can be very effective at L4-5 where the anatomy of the iliac crest or lumbar plexus does not preclude this surgical corridor the way it could in the transpsoas lateral lumbar interbody fusion. Clinical outcomes between these 2 lateral approaches have been shown to be very good,9 and OLIF has reduced blood loss while still restoring alignment parameters compared with anterior lumbar interbody fusion, with better fusion and reduced subsidence compared with transforaminal lumbar interbody fusion.10,11 To our knowledge, this is the first video demonstrating a view of the OLIF approach through a high-definition retractor-based camera (MaxView Camera, Viseon Inc). There is no identifying patient information in this video. The participants and any identifiable individuals consented to publication of his/her image, and the patient consented to the procedure.

Intra-abdominal Content Movement in Prone Versus Lateral Decubitus Position Lateral Lumbar Interbody Fusion (LLIF).

A prospective, anatomical imaging study of healthy volunteer subjects in accurate surgical positions. To establish if there is a change in the position of the abdominal contents in the lateral decubitus (LD) versus prone position. Lateral transpsoas lumbar interbody fusion (LLIF) in the LD position has been validated anatomically and for procedural safety, specifically in relation to visceral risks. Recently, LLIF with the patient in the prone position has been suggested as an alternative to LLIF in the LD position. Subjects underwent magnetic resonance imaging of the lumbosacral region in the right LD position with the hips flexed and the prone position with the legs extended. Anatomical measurements were performed on axial magnetic resonance images at the L4-5 disc space. Thirty-four subjects were included. The distance from the skin to the lateral disc surface was 134.9mm in prone compared with 118.7mm in LD ( P <0.0001). The distance between the posterior aspect of the disc and the colon was 20.3mm in the prone compared with 41.1mm in LD ( P <0.0001). The colon migrated more posteriorly in relation to the anterior margin of the psoas in the prone compared with LD (21.7 vs . 5.5mm, respectively; P <0.0001). 100% of subjects had posterior migration of the colon in the prone compared with the LD position, as measured by the distance from the quadratum lumborum to the colon (44.4 vs . 20.5mm, respectively; P <0.001). There were profound changes in the position of visceral structures between the prone and LD patient positions in relation to the LLIF approach corridor. Compared with LD LLIF, the prone position results in a longer surgical corridor with a substantially smaller working window free of the colon, as evidenced by the significant and uniform posterior migration of the colon. Surgeons should be aware of the potential for increased visceral risks when performing LLIF in the prone position. Level II-prospective anatomical cohort study.

184 Clinical Outcomes of the Prone Transpsoas Lateral Lumbar Interbody Fusion for Degenerative Lumbar Spine Disease: A Multicentre Study

INTRODUCTION: The prone transpsoas lateral lumbar interbody fusion (PTP) is a novel technique for degenerative lumbar spine disease. However, there is a paucity of the literature on the clinical outcomes of this procedure, with all the published being of a small sample size. METHODS: A retrospective electronic medical records review was conducted in ten centers for patients who underwent PTP. We collected the intraoperative data (operative time, estimated blood loss [EBL], intraoperative complications [anterior longitudinal ligament (ALL) rupture, cage subsidence, vascular and visceral injuries), postoperative complications, the patient-reported outcome measures (PROMS) such as back pain visual analogue scale (VAS), and hospital stay. RESULTS: A total of 350 patients were included in the study. There was a significant improvement in the mean VAS by 4.4 ± 6.7 (p &lt; 0.001). 2.8% had ALL rupture, 1.2% had cage subsidence, 0.4% had a vascular injury, and none had visceral injuries. The mean operative time was 229.9 ± 144 minutes, the mean EBL was 134.3±210.2 mL, and the mean hospital stay was 2.6 ± 2.2. In regard to postoperative complications, there was 8.9% new sensory symptoms, 6% transient hip flexor weakness, 1.4% wound infection, 1.4% cage subsidence, 0.6% psoas hematoma, 0.3% ureteric injury, 0.3% small bowel obstruction/ischemia, and 1.6% 90-days readmission. CONCLUSIONS: Multicenter consecutive case series show that PTP is well tolerated and has satisfactory clinical outcomes.

Commentary: Prone Transpsoas Lateral Lumbar Interbody Fusion for Degenerative Lumbar Spine Disease: Case Series With an Operative Video Using Fluoroscopy-Based Instrument Tracking Guidance.

Hadi, Moustafa BS*; Deshpande, Nachiket BS*; Hamilton, Travis MD‡; Chang, Victor MD‡ Author Information

Multilevel tandem spondylolisthesis associated with a reduced "safe zone" for a transpsoas lateral lumbar interbody fusion at L4–5

The aim of this study was to investigate the effect of degenerative spondylolisthesis (DS) on psoas anatomy and the L4-5 safe zone during lateral lumbar interbody fusion (LLIF). In this retrospective, single-institution analysis, patients managed for low-back pain between 2016 and 2021 were identified. Inclusion criteria were adequate lumbar MR images and radiographs. Exclusion criteria were spine trauma, infection, metastases, transitional anatomy, or prior surgery. There were three age and sex propensity-matched cohorts: 1) controls without DS; 2) patients with single-level DS (SLDS); and 3) patients with multilevel, tandem DS (TDS). Axial T2-weighted MRI was used to measure the apical (ventral) and central positions of the psoas relative to the posterior tangent line at the L4-5 disc. Lumbar lordosis (LL), pelvic incidence (PI), pelvic tilt (PT), sacral slope (SS), and PI-LL mismatch were measured on lumbar radiographs. The primary outcomes were apical and central psoas positions at L4-5, which were calculated using stepwise multivariate linear regression including demographics, spinopelvic parameters, and degree of DS. Secondary outcomes were associations between single- and multilevel DS and spinopelvic parameters, which were calculated using one-way ANOVA with Bonferroni correction for between-group comparisons. A total of 230 patients (92 without DS, 92 with SLDS, and 46 with TDS) were included. The mean age was 68.0 ± 8.9 years, and 185 patients (80.4%) were female. The mean BMI was 31.0 ± 7.1, and the mean age-adjusted Charlson Comorbidity Index (aCCI) was 4.2 ± 1.8. Age, BMI, sex, and aCCI were similar between the groups. Each increased grade of DS (no DS to SLDS to TDS) was associated with significantly increased PI (p < 0.05 for all relationships). PT, PI-LL mismatch, center psoas, and apical position were all significantly greater in the TDS group than in the no-DS and SLDS groups (p < 0.05). DS severity was independently associated with 2.4-mm (95% CI 1.1-3.8 mm) center and 2.6-mm (95% CI 1.2-3.9 mm) apical psoas anterior displacement per increased grade (increasing from no DS to SLDS to TDS). TDS represents more severe sagittal malalignment (PI-LL mismatch), pelvic compensation (PT), and changes in the psoas major muscle compared with no DS, and SLDS and is a risk factor for lumbar plexus injury during L4-5 LLIF due to a smaller safe zone.

Female Sex and Supine Proximal Lumbar Lordosis Are Associated With the Size of the LLIF "Safe Zone" at L4-L5.

Retrospective chart review. Identify demographic and sagittal alignment parameters that are independently associated with femoral nerve position at the L4-L5 disk space. Iatrogenic femoral nerve or lumbar plexus injury during lateral lumbar interbody fusion (LLIF) can result in neurological complications. The LLIF "safe zone" is the anterior half to two third of the disk space. However, femoral nerve position varies and is inconsistently identifiable on magnetic resonance imaging. The safe zone is also narrowest at L4-L5. An analysis of patients with symptomatic lumbar spine pathology and magnetic resonance imaging with a visibly identifiable femoral nerve evaluated at a single large academic spine center from January 1, 2017, to January 8, 2020, was performed. Exclusion criteria were transitional anatomy, severe hip osteoarthritis, coronal deformity with cobb >10 degrees, > grade 1 spondylolisthesis at L4-L5 and anterior migration of the psoas.Standing and supine lumbar lordosis (LL) and its proximal (L1-L4) and distal (L4-S1) components were measured. Femoral nerve position on sagittal imaging was then measured as a percentage of the L4 inferior endplate. A stepwise multivariate linear regression of sagittal alignment and LL parameters was then performed. Data are written as estimate, 95% CI. Mean patient age was 58.2±14.7 years, 25 (34.2%) were female and 26 (35.6%) had a grade 1 spondylolisthesis. Mean femoral nerve position was 26.6±10.3% from the posterior border of L4. Female sex (-6.6, -11.1 to -2.1) and supine proximal lumbar lordosis (0.4, 0.1-0.7) were independently associated with femoral nerve position. Patient sex and proximal LL can serve as early indicators of the size of the femoral nerve safe zone during a transpsoas LLIF approach at L4-L5.

Radiological and Clinical Outcomes comparing 2-level MIS Lateral and MIS Transforaminal Lumbar Interbody Fusion in Degenerative Lumbar Spinal Stenosis.

Retrospective Cohort Study. To compare early postoperative radiological and clinical outcomes between 2-level minimally invasive (MIS) trans-psoas lateral lumbar interbody fusion (LLIF) and MIS transforaminal lumbar interbody fusion (TLIF) for degenerative lumbar spinal stenosis. Fifty three consecutive patients undergoing 2-level lumbar interbody fusion from L3-L5 for degenerative lumbar spinal stenosis were enrolled. Twenty four patients underwent LLIF and 29 underwent TLIF. Operative time and length of stay were similar between LLIF and TLIF (272.8 ± 82.4 vs 256.1 ± 59.4 minutes; 5.5 ± 2.8 vs 4.7 ± 3.3 days, P > .05), whereas blood loss was lower for LLIF (229.0 ± 125.6 vs 302.4 ± 97.1mls, P = .026). Neurological deficits were more common in LLIF (9 vs 3, P = .025), whereas persistent deficits were rare for both (1 vs 1, P = 1). For both groups, all patient reported outcomes visual analogue scale (VAS back pain, VAS leg pain, ODI, SF-36 physical) improved from preoperative to 2-years postoperative (P < .05), with both groups showing no significant differences in extent of improvement for any outcome. Lateral lumbar interbody fusion demonstrated superior restoration of disc height (L3-L4: 4.1 ± 2.4 vs 1.2 ± 1.9mm, P < .001; L4-L5: 4.6 ± 2.4 vs .8 ± 2.8mm, P < .001), foraminal height (FH) (L3-L4: 3.5 ± 3.6 vs 1.0 ± 3.6mm, P = .014; L4-L5: 3.0 ± 3.5 vs -.1 ± 4.4mm, P = .0080), segmental lordosis (4.1 ± 6.4 vs -2.1 ± 8.1°, P = .005), lumbar lordosis (LL) (4.1 ± 7.0 vs -2.3 ± 12.6°, P = .026) and pelvic incidence-lumbar lordosis (PI-LL) mismatch (-4.1 ± 7.0 vs 2.3 ± 12.6°, P = .019) at 2-years follow-up. The superior radiological outcomes demonstrated by 2-level trans-psoas LLIF did not translate into difference in clinical outcomes compared to 2-level TLIF at the 2-years follow-up, suggesting both approaches are reasonable for 2-level lumbar interbody fusion in degenerative lumbar spinal stenosis.

Assessing the differences in operative and patient-reported outcomes between lateral approaches for lumbar fusion: a systematic review and indirect meta-analysis.

Anterior-to-psoas lumbar interbody fusion (ATP-LIF), more commonly referred to as oblique lateral interbody fusion, and lateral transpsoas lumbar interbody fusion (LTP-LIF), also known as extreme lateral interbody fusion, are the two commonly used lateral approaches for performing a lumbar fusion procedure. These approaches help overcome some of the technical challenges associated with traditional approaches for lumbar fusion. In this systematic review and indirect meta-analysis, the authors compared operative and patient-reported outcomes between these two select approaches using available studies. Using the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) approach, the authors conducted an electronic search using the PubMed, EMBASE, and Scopus databases for studies published before May 1, 2019. Indirect meta-analysis was conducted on fusion rate, cage movement (subsidence plus migration), permanent deficits, and transient deficits; results were depicted as forest plots of proportions (effect size [ES]). A total of 63 studies were included in this review after applying the exclusion criteria, of which 26 studies investigated the outcomes of ATP-LIF, while 37 studied the outcomes of LTP-LIF. The average fusion rate was found to be similar between the two groups (ES 0.97, 95% CI 0.84-1.00 vs ES 0.94, 95% CI 0.91-0.97; p = 0.561). The mean incidence of cage movement was significantly higher in the ATP-LIF group compared with the LTP-LIF group (stand-alone: ES 0.15, 95% CI 0.06-0.27 vs ES 0.09, 95% CI 0.04-0.16 [p = 0.317]; combined: ES 0.18, 95% CI 0.07-0.32 vs ES 0.02, 95% CI 0.00-0.05 [p = 0.002]). The mean incidence of reoperations was significantly higher in patients undergoing ATP-LIF than in those undergoing LTP-LIF (ES 0.02, 95% CI 0.01-0.03 vs ES 0.04, 95% CI 0.02-0.07; p = 0.012). The mean incidence of permanent deficits was similar between the two groups (stand-alone: ES 0.03, 95% CI 0.01-0.06 vs ES 0.05, 95% CI 0.01-0.12 [p = 0.204]; combined: ES 0.03, 95% CI 0.01-0.06 vs ES 0.03, 95% CI 0.00-0.08 [p = 0.595]). The postoperative changes in visual analog scale (VAS) and Oswestry Disability Index (ODI) scores were both found to be higher for ATP-LIF relative to LTP-LIF (VAS: weighted average 4.11 [SD 2.03] vs weighted average 3.75 [SD 1.94] [p = 0.004]; ODI: weighted average 28.3 [SD 5.33] vs weighted average 24.3 [SD 4.94] [p < 0.001]). These analyses indicate that while both approaches are associated with similar fusion rates, ATP-LIF may be related to higher odds of cage movement and reoperations as compared with LTP-LIF. Furthermore, there is no difference in rates of permanent deficits between the two procedures.

68. Female sex and supine proximal lumbar lordosis is associated with the size of the LLIF ‘safe zone’ at L4-5

68. Female sex and supine proximal lumbar lordosis is associated with the size of the LLIF ‘safe zone’ at L4-5

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.

Single-position circumferential lumbar spinal fusion: an overview of terminology, concepts, rationale and the current evidence base.

To provide definitions and a conceptual framework for single position surgery (SPS) applied to circumferential fusion of the lumbar spine. Narrative literature review and experts' opinion. Two major limitations of lateral lumbar interbody fusion (LLIF) have been (a) a perceived need to reposition the patient to the prone position for posterior fixation, and (b) the lack of a robust solution for fusion at the L5/S1 level. Recently, two strategies for performing single-position circumferential lumbar spinal fusion have been described. The combination of anterior lumbar interbody fusion (ALIF) in the lateral decubitus position (LALIF), LLIF and percutaneous pedicle screw fixation (pPSF) in the lateral decubitus position is known as lateral single-position surgery (LSPS). Prone LLIF (PLLIF) involves transpsoas LLIF done in the prone position that is more familiar for surgeons to then implant pedicle screw fixation. This can be referred to as prone single-position surgery (PSPS). In this review, we describe the evolution of and rationale for single-position spinal surgery. Pertinent studies validating LSPS and PSPS are reviewed and future questions regarding the future of these techniques are posed. Lastly, we present an algorithm for single-position surgery that describes the utility of LALIF, LLIF and PLLIF in the treatment of patients requiring AP lumbar fusions. Single position surgery in circumferential fusion of the lumbar spine includes posterior fixation in association with any of the following: lateral position LLIF, prone position LLIF, lateral position ALIF, and their combination (lateral position LLIF+ALIF). Preliminary studies have validated these methods.

Transitioning from lateral to the prone transpsoas approach: flatten the learning curve by knowing the nuances.

Prone transpsoas lateral lumbar interbody fusion is the newest frontier in surgical approach to the lumbar spine. Prone positioning facilitates segmental lordosis and facile posterior segmental fixation. However, even in experienced hands, transitioning from a lateral decubitus to prone position necessitates alterations to the traditional technique. In this video, the authors highlight the nuances of adopting the prone transpsoas lateral lumbar interbody fusion technique and strategies to overcome them.The video can be found here: https://stream.cadmore.media/r10.3171/2022.3.FOCVID2224

Saphenous somatosensory-evoked potentials monitoring of femoral nerve health during prone transpsoas lateral lumbar interbody fusion.

To assess whether saphenous somatosensory-evoked potentials (saphSSEP) monitoring may provide predictive information of femoral nerve health during prone lateral interbody fusion (LIF) procedures. Intraoperative details were captured prospectively in consecutive prone LIF surgeries at a single institution. Triggered electromyography was used during the approach; saphSSEP was monitored throughout using a novel system that enables acquisition of difficult signals and real-time actionable feedback facilitating intraoperative intervention. Postoperative neural function was correlated with intraoperative findings. Fifty-nine patients (58% female, mean age 64, mean BMI 32) underwent LIF at 95 total levels, inclusive of L4-5 in 76%, fixated via percutaneous pedicle screws (81%) or lateral plate, with direct decompression in 39%. Total operative time averaged 149min. Psoas retraction time averaged 16min/level. Baseline SSEPs were unreliable in 3due to comorbidities in 2and anesthesia in1; one of those resulted in transient quadriceps weakness, fully recovered at 6weeks. In 25/56, no saphSSEP changes occurred, and none had postoperative femoral nerve deficits. In 24/31 with saphSSEP changes, responses recovered intraoperatively following intervention, with normal postoperative function in all but one with delayed quadriceps weakness, improved at 4months and recovered at 9months, and a second with transient isolated anterior thigh numbness. In the remaining 7/31, saphSSEP changes persisted to close, and resulted in 2 transient isolated anterior thigh numbness and 2 combined sensory and motor femoral nerve deficits, both resolved at between 4 and 8months. SaphSSEP was reliably monitored in most cases and provided actionable feedback that was highly predictive of neurological events during LIF. Diagnostic: individual cross-sectional studies with consistently applied reference standard and blinding.

Outcomes following transpsoas lateral lumbar interbody fusion

The transpsoas lateral lumbar interbody fusion (LLIF) is utilized to treat multiple spinal conditions ranging from degenerative disorders to spinal deformities. The transpsoas LLIF was developed to limit the vascular complications of the anterior lumbar approach and minimize extensive soft tissue dissection and neural manipulation of the posterior approach. Compared to other fusion techniques, the transpsoas LLIF has demonstrated more favorable clinical outcomes (lower VAS and ODI scores), a greater improvement in radiological outcomes, lower risk of bleeding, shorter operative times, and higher fusion rates. It is a cost-effective technique that is associated with a shorter length of stay, lower reoperation/readmission rates, and minimal risk of complications. This review provides an overview of transpsoas LLIF and highlights the surgical outcomes, including operative and postoperative complications associated with this surgical technique.

A New Treatment Algorithm That Incorporates Minimally Invasive Surgery for Pyogenic Spondylodiscitis in the Thoracic and Lumbar Spines: The Results of Its Clinical Application to a Series of 34 Patients.

Background and Objectives: Spinal minimally invasive surgery (MIS) experts at the university hospital worked as a team to develop a new treatment algorithm for pyogenic spondylodiscitis in lumbar and thoracic spines. They modified a flow chart introduced for this condition in a pre-MIS era to incorporate MIS techniques based on their extensive experiences accumulated over the years, both in MIS for degenerative lumbar diseases and in the treatment of spine infections. The MIS procedures incorporated in this algorithm consisted of percutaneous pedicle screw (PPS)–rod fixation and transpsoas lateral lumbar interbody fusion (LLIF). The current study analyzed a series of 34 patients treated with prospective selection of the methods according to this new algorithm. Materials and Methods: The algorithm first divided the patients into those who had escaped complicated disease conditions, such as neurologic impairment, extensive bone destruction, and the need to be mobilized without delay (Group 1) (19), and those with complicated pyogenic spondylodiscitis (Group 2) (15). Group 1 had image-guided needle biopsy followed by conservative treatment alone with antibiotics and a spinal brace (12) (Group 1-A) or a subsequent addition of non-fused PPS–rod fixation (7) (Group 1-B). Group 2 underwent an immediate single-stage MIS with non-fused PPS–rod fixation followed by posterior exposure for decompression and debridement through a small midline incision (12) (Group 2-A) or an additional LLIF procedure after an interval of 3 weeks (3) (Group 2-B). Results: All patients, except four, who either died from causes unrelated to the spondylodiscitis (2) or became lost to follow up (2), were cured of infection with normalized CRP at an average follow up of 606 days (105–1522 days). A solid interbody fusion occurred at the affected vertebrae in 15 patients (50%). Of the patients in Group 2, all but two regained a nearly normal function. Despite concerns about non-fused PPS–rod instrumentation, only seven patients (21%) required implant removal or replacement. Conclusions: Non-fused PPS–rod placements into infection-free vertebrae alone or in combination with posterior debridement through a small incision worked effectively in providing local stabilization without contamination of the metal implant from the infected tissue. MIS LLIF allowed for direct access to the infected focus for bone grafting in cases of extensive vertebral body destruction.

Single-position prone lateral transpsoas approach: early experience and outcomes.

Lateral lumbar interbody fusion (LLIF) via a transpsoas approach is a workhorse minimally invasive approach for lumbar arthrodesis that is often combined with posterior pedicle screw fixation. There has been increasing interest in performing single-position surgery, allowing access to the anterolateral and posterior spine without requiring patient repositioning. The feasibility of the transpsoas approach in patients in the prone position has been reported. Herein, the authors present a consecutive case series of all patients who underwent single-position prone transpsoas LLIF performed by an individual surgeon since adopting this approach. A retrospective review was performed of a consecutive case series of adult patients (≥ 18 years old) who underwent single-position prone LLIF for any indication between October 2019 and November 2020. Pertinent operative details (levels, cage use, surgery duration, estimated blood loss, complications) and 3-month clinical outcomes were recorded. Intraoperative and 3-month postoperative radiographs were reviewed to assess for interbody subsidence. Twenty-eight of 29 patients (97%) underwent successful treatment with the prone lateral approach over the study interval; the approach was aborted in 1 patient, whose data were excluded. The mean (SD) age of patients was 67.9 (9.3) years; 75% (21) were women. Thirty-nine levels were treated: 18 patients (64%) had single-level fusion, 9 (32%) had 2-level fusion, and 1 (4%) had 3-level fusion. The most commonly treated levels were L3-4 (n = 15), L2-3 (n = 12), and L4-5 (n = 11). L1-2 was fused in 1 patient. The mean operative time was 286.5 (100.6) minutes, and the mean retractor time was 29.2 (13.5) minutes per level. The mean fluoroscopy duration was 215.5 (99.6) seconds, and the mean intraoperative radiation dose was 170.1 (94.8) mGy. Intraoperative subsidence was noted in 1 patient (4% of patients, 3% of levels). Intraoperative lateral access complications occurred in 11% of patients (1 cage repositioning, 2 inadvertent ruptures of anterior longitudinal ligament). Subsidence occurred in 5 of 22 patients (23%) with radiographic follow-up, affecting 6 of 33 levels (18%). Postoperative functional testing (Oswestry Disability Index, SF-36, visual analog scale-back and leg pain) identified significant improvement. This single-surgeon consecutive case series demonstrates that this novel technique is well tolerated and has acceptable clinical and radiographic outcomes. Larger patient series with longer follow-up are needed to further elucidate the safety profile and long-term outcomes of single-position prone LLIF.

Comparison of Prone Transpsoas and Standard Lateral Lumbar Interbody Fusion Surgery for Degenerative Lumbar Spine Disease: A Retrospective Radiographic Propensity Score-Matched Analysis

Prone transpsoas lateral lumbar interbody fusion (PTP-LLIF) is a recently introduced modification to standard LLIF. To date, no study has compared the radiographic outcomes of standard LLIF and PTP-LLIF. We performed a radiographic parameter-based propensity score-matched analysis to compare postoperative clinical and radiographic outcomes between PTP-LLIF and standard LLIF for degenerative lumbar spine disease. A total of 30 consecutive patients met the inclusion criteria. The preoperative standing scoliosis radiographs were retrospectively reviewed for global and segmental sagittal alignment. Propensity score matching was calculated using the baseline radiographic parameters. One-to-one matching of patients who had undergone PTP-LLIF with those who had a similar propensity score but had undergone standard LLIF was performed to compare the radiographic (primary) and clinical (secondary) outcomes. Propensity score matching resulted in 10 pairs of PTP-LLIF and standard LLIF patients. The PTP-LLIF group had had significantly better improvement in lumbar lordosis (P= 0.047). The difference in the improvement in pelvic incidence minus lumbar lordosis mismatch approached statistical significance for the PTP-LLIF group (P= 0.05). This led to better improvement in the short-form 12-item physical score (P= 0.03) and Oswestry disability index (P= 0.1) in the PTP-LLIF group. No significant differences were found between the 2 groups in the other clinical and radiographic outcomes. The PTP-LLIF group had a shorter operative time (P= 0.4) and hospital stay (P= 0.1), without a statistically difference, and shorter radiation exposure time (P= 0.5). The standard LLIF group had experienced less intraoperative bleeding, without a statistically significant difference (P= 0.3). The mean follow-up time was 10.2 ± 5.2 months in the PTP-LLIF group and 30.9 ± 17.2 months in the standard LLIF group (P < 0.05). The PTP-LLIF group showed significantly better improvement in lumbar lordosis and short-form 12-item physical score.

202. Are neuromonitoring alerts predictive of postoperative deficits in lateral lumbar interbody fusion?

<h3>BACKGROUND CONTEXT</h3> Transpsoas lateral lumbar interbody fusion (LLIF) is associated with known approach related neurologic risk. Directional EMG and neuromonitoring (NM; SSEP and MEP) are frequently used. <h3>PURPOSE</h3> Should NM be recommended for LLIF? We aim to investigate the use of NM and its ability in LLIF to avoid postoperative deficit (POD). <h3>STUDY DESIGN/SETTING</h3> Single institution retrospective review of two surgeons' consecutive LLIF patients. <h3>PATIENT SAMPLE</h3> This study included 169 consecutive patients undergoing LLIF without concurrent ALIF or TLIF and complete NM data over 4 years (2014-2018) with 2-year follow-up. Total patients included: 127 degenerative (74.7%), 41 deformity (24.1%), 1 trauma (0.5%), 1 infection (0.5%). <h3>OUTCOME MEASURES</h3> NM alerts: Number of alerts, type of alert (SSEP, EMG, MEP), timing of the alert. POD: sensory (S) and motor (M). Psoas weakness: persistence >3months considered POD. Retractor time: mean per level, NM alert, and POD. <h3>METHODS</h3> Retrospective review of prospectively collected intraop NM data. NM alerts were defined as sustained EMG or 50% change in baseline SSEP or MEP. POD defined as a new M or S deficit associated with approach level; baseline, immediate postop, 1 month, 3 months, until resolution or up to 2 years were reviewed. Psoas weakness persistence >3months considered POD. <h3>RESULTS</h3> At total of 169 patients (266 levels) were included (67M, 102F). Twenty-four (14.2%) patients had NM alert (4 SSEP, 15 MEP, 9 EMG). Seventeen alerts occurred at L4-L5 (70.8%), 6 at L3-L4 (25%), 1 at L2-L3 (4.2%). Mean time to first alert was 19.65 minutes. Sixteen (9.46%) patients had a total of 18 POD; (4 pt S, 10 patients M, 2 patients both). Four patients with POD had NM alerts (2.4%); all 4 had M (p=0.039) and 2 also had S (p=0.189). Sensitivity (Sn) of NM alerts to detect any deficit: 0.25; specificity (Sp) of NM alerts to detect any deficit: 0.876; Sn of NM alerts to detect M: 0.33; Sp of NM alerts to detect M: 0.879. OR for NM alert to detect any deficit: 2.35 (0.69-8.04), p=0.17, OR for NM alert to detect M: 3.63 (0.99-13.23), p=0.05. No difference in incidence of POD across diagnosis. All POD recovered by 2 years except 1 pt had persistent M. 37 patients (21.89%) had psoas weakness, 4 (2.37%) remained at 3 months and were considered POD. No difference in retractor time in patients with and without POD. Mean retractor time without POD 19.78 min (SD 7.3) and with POD 19.75 min (SD 4.2). <h3>CONCLUSIONS</h3> Twenty-four patients had NM alerts triggering a response with only 4 waking with POD suggesting that 20 patients potentially averted POD. Specificity is high for all deficits and motor suggesting that NM alerts are important predictors for physicians to take corrective actions. However, the sensitivity is low, suggesting that further investigation is required to understand why PODs are occurring in the absence of NM alerts. <h3>FDA DEVICE/DRUG STATUS</h3> This abstract does not discuss or include any applicable devices or drugs.