Lateral Transpsoas Research Articles

Anatomical Study of the Extreme Lateral Transpsoas Lumbar Interbody Fusion with Application to Minimizing Injury to the Kidney.

ObjectiveSince the extreme lateral lumbar interbody fusion procedure was first reported by Ozgur in 2006, a large number of clinical studies have been published. Anatomical studies which explore methods to avoid visceral structures, such as the kidney, with this approach have not been examined in detail. We dissected the retroperitoneal space to analyze how the extreme lateral transpsoas approach to the lumbar spine could damage the kidney and related structures.MethodsEight sides from four fresh Caucasian cadavers were used for this study. The latissimus dorsi muscle and the thoracolumbar fascia were dissected to open the retroperitoneum. The fat tissue was removed. Steel wires were then put into the intervertebral disc spaces. Finally, the closest distance between kidney and wires on each interdiscal space was measured.ResultsThe closest distance from the wire in the interdiscal space on L1/2, L2/3 and L3/4 to the kidney ranged from 13.2 mm to 32.9 mm, 20.0 mm to 27.7 mm, and 20.5 mm to 46.6 mm, respectively. The distance from the kidney to the interdiscal space at L4/5 was too great to be considered applicable to this study.ConclusionsThe results of this study might help surgeons better recognize the proximity of the kidney and avoid injury to it during the extreme lateral transpsoas approach to the lumbar spine.

Intraoperative neurophysiological monitoring during spinal surgery: technical review in open and minimally invasive approaches.

Neurophysiological monitoring is of undoubted value for the intraoperative safety of neurosurgical procedures. Widely developed and used for cranial surgery, it is equally as effective, though perhaps less commonly employed, for spinal pathology. The most frequently used techniques for intraoperative monitoring during spinal surgery include somatosensory evoked potentials (SSEPs), motor evoked potentials (MEPs) and electromyography, which can either be spontaneous free-running (sEMG) or triggered (tEMG). The knowledge of the benefits and limitations of each modality is essential in optimising the value of intraoperative monitoring during spinal procedures. This review will analyse the single techniques, their anatomical and physiological basis, their use in spinal surgery as reliable indicators of functional injury, their limits and their application to specific procedures in minimally invasive surgery, such as the lateral transpsoas access for interbody fusion and the divergent trajectory for cortico-pedicular screws. In these particular techniques, because of reduced visual exposure, neuromonitoring is indeed essential to exploit the full potential of minimally invasive surgery, while avoiding damage to nervous structures.

Anatomical Modifications during the Lateral Transpsoas Approach to the Lumbar Spine. The Impact of Vertebral Rotation.

We investigated impact of vertebral axial rotation on neurovascular anatomy in adult spinal deformity (ASD) patients and provided recommendations on the approach based on degree of axial rotation. In order to isolate vertebral rotation (VR) impact from the superimposed degenerative cascade observed in adulthood, adolescent idiopathic scoliosis (AIS) patients were analyzed. Magnetic resonance imaging (MRI) scans (L1-S1) from 50 right-convex thoracic (left-convex lumbar) AIS patients were analyzed. At each intervertebral level, VR, lumbar plexus depth (LPD), and vascular structure depth (VSD) were evaluated. Paired t test analyses were used to describe anatomic differences between the concave and convex aspect of our patients' curves. Correlation analysis was used to investigate relationships with soft tissue modifications and VR. Fifty AIS patients (17M, 33F) with mean thoracic Cobb of 50.6° ± 17.0° and mean lumbar Cobb of 41.9° ± 13.0° were included. Mean VR at each level was L1-2 = -6.6°, L2-3 = -7.7°, L3-4 = -6.5°, L4-5 = -4.7°, L5-S1 = -2.6° (negative value denotes clockwise rotation). We found significant differences (P < .05) between concave-convex (right-left) LPD at each level (L1-2 = 3.7 mm, L2-3 = 5.1 mm, L3-4 = 4.2 mm, L4-5 = 2.2 mm, L5-S1 = 2.2 mm). Vascular structure depth was significantly different at L1-L2 (3.2 mm) and L5-S1 (3 mm). Significant correlation was found between increasing VR and concave-convex LPD difference (r = 0.68, P < .001). This study demonstrates that displacement of the lumbar plexus is tied to the magnitude of VR in patients with AIS. When approaching the lumbar spine, this displacement widens the safe surgical corridor on the convex side and narrows the corridor on the concave side. IV. Preoperative review of MRI scans should occur to assess the patient's safe surgical corridor for lateral lumbar interbody fusion (LLIF). Adult spinal deformity surgeons who approach a degenerated spine in patients with progressive AIS in adulthood must carefully plan for patient positioning, neurovascular anatomy, and realignment objectives prior to the day of surgical intervention.

Minimally invasive anterior and lateral transpsoas approaches for closed reduction of grade II spondylolisthesis: initial clinical and radiographic experience.

OBJECTIVE Minimally invasive anterior and lateral approaches to the lumbar spine are increasingly used to treat and reduce grade I spondylolisthesis, but concerns still exist for their usage in the management of higher-grade lesions. The authors report their experience with this strategy for grade II spondylolisthesis in a single-surgeon case series and provide early clinical and radiographic outcomes. METHODS A retrospective review of a single surgeon's cases between 2012 and 2016 identified all patients with a Meyerding grade II lumbar spondylolisthesis who underwent minimally invasive lateral lumbar interbody fusion (LLIF) or anterior lumbar interbody fusion (ALIF) targeting the slipped level. Demographic, clinical, and radiographic data were collected and analyzed. Changes in radiographic measurements, Oswestry Disability Index (ODI), and visual analog scale (VAS) scores were compared using the paired t-test and Wilcoxon signed rank test for continuous and ordinal variables, respectively. RESULTS The average operative time was 199.1 minutes (with 60.6 ml of estimated blood loss) for LLIFs and 282.1 minutes (with 106.3 ml of estimated blood loss), for ALIFs. Three LLIF patients had transient unilateral anterior thigh numbness during the 1st week after surgery, and 1 ALIF patient had transient dorsiflexion weakness, which was resolved at postoperative week 1. The mean follow-up time was 17.6 months (SD 12.5 months) for LLIF patients and 10 months (SD 3.1 months) for ALIF patients. Complete reduction of the spondylolisthesis was achieved in 12 LLIF patients (75.0%) and 7 ALIF patients (87.5%). Across both procedures, there was an increase in both the segmental lordosis (LLIF 5.6°, p = 0.002; ALIF 15.0°, p = 0.002) and overall lumbar lordosis (LLIF 2.9°, p = 0.151; ALIF 5.1°, p = 0.006) after surgery. Statistically significant decreases in the mean VAS and the mean ODI measurements were seen in both treatment groups. The VAS and ODI scores fell by a mean value of 3.9 (p = 0.002) and 19.8 (p = 0.001), respectively, for LLIF patients and 3.8 (p = 0.02) and 21.0 (p = 0.03), respectively, for ALIF patients at last follow-up. CONCLUSIONS Early clinical and radiographic results from using minimally invasive LLIF and ALIF approaches to treat grade II spondylolisthesis appear to be good, with low operative blood loss and no neurological deficits. Complete reduction of the spondylolisthesis is frequently possible with a statistically significant reduction in pain scores.

Radiographic Analysis of Psoas Morphology and its Association With Neurovascular Structures at L4-5 With Reference to Lateral Approaches.

Retrospective imaging review. Utilize magnetic resonance imaging (MRI) to expand the anatomical description of psoas morphology and its association with neurovascular structures at L4-5. Anatomical psoas muscle variants may present a greater risk of neurovascular injury at the L4-5 level during lateral transpsoas approaches. Axial L4-5 sections of consecutive patients who obtained lumbar MRIs were analyzed. Teardrop psoas morphology was assessed qualitatively. MRI described psoas morphology and proximity of neurovascular structures, whereas plain radiographs were evaluated for lumbosacral transitional vertebrae (LSTV). Teardrop morphology was tested for associations with radiographic measurements using t tests and χ analysis. Fifty teardrop and 476 nonteardrop psoas muscles were identified. Teardrop morphology was associated with greater longitudinal length (53.1 vs. 49.3 mm, P = 0.012), and shorter transverse length (34.9 vs. 44.8 mm, P < 0.001) compared with nonteardrop. Teardrop morphology was associated with anterior and lateral migration of the psoas with greater distance between the anterior borders of the psoas and disc (13.5 vs. 6.3 mm, P < 0.001), and greater distance between the medial border of the psoas to the lateral disc border (1.6 vs. 0.5 mm, P < 0.001). Teardrop morphology was associated with a higher incidence of the lumbar plexus migrating anteriorly adjacent to the middle-third of the disc (43.4% vs. 17.6%, P < 0.001) and the iliac vasculature being more laterally and posteriorly located, adjacent to the anterior-third of the disc (43.4% vs. 30.0%, P = 0.047). Teardrop morphology was not associated with presence of LSTV (3.8% vs. 7.6%, P = 0.306). The current study provides detailed metrics of teardrop psoas muscles and surrounding structures. The study confirms that the presence of teardrop anatomy on L4-5 axial imaging is associated with anterior migration of the lumbar plexus and posterolateral migration of the iliac vasculature which may increase the risk of neurovascular injury during direct and oblique-lateral lumbar spine procedures. 3.

Hip Flexion Weakness following Transpsoas Interbody Fusion

Objective The present work evaluated the motor deficit resulting from the psoas muscle access through the extreme lateral interbody fusion (XLIF) approach. Methods This was a prospective, non-randomized, controlled, single-center study with 60 patients, with a mean age of 61.8 years old. All of the subjects underwent a lateral transpsoas retroperitoneal approach for lumbar interbody fusion with electroneuromyographic guidance and accessing 1 to 3 lumbar levels (mean level, 1.4; 63% cases in only 1 level; 68% cases included L4-L5). The isometric hip flexion strength in the sitting position was determined bilaterally with a handheld dynamometer (Lafayette Instrument, Lafayette, IN, USA). The mean value of three peak force measurements (N) was calculated. Standardized isometric strength tests were performed before the procedure and at 10 days, 6 weeks, 3 months and 6 months postsurgery. Results Ipsilateral hip flexion was diminished (p &lt; 0.001) at the early postoperative period, but reached preoperative values at 6 weeks (p &gt; 0.12). The mean hip flexion measures before the procedure and at 10 days, 6 weeks, 3 months and 6 months after surgery were the following, respectively: 13 N; 9.7 N; 13.7 N; 14.4 N; and 16 N (ipsilateral); 13.3 N; 13.4 N; 15.3 N; 15.9 N; and 16.1 N (contralateral). Neither the level nor the number of treated levels had a clear association with thigh symptoms, but hip flexion weakness was the most common symptom. Conclusions Patients in the early postoperative period of transpsoas access presented hip flexion weakness. However, this weakness was transient, and electroneuromyography use is still imperative in transpsoas access. In addition, patients must be thoroughly educated about hip flexion weakness to prevent falls in the immediate postoperative period.

Variation in Psoas Muscle Location Relative to the Safe Working Zone for L4/5 Lateral Transpsoas Interbody Fusion: A Morphometric Analysis.

The safe working zone for lateral access to the L4/5 disc space has been said to lie in the anteroposterior (AP) midpoint of the disc space due to the location of the femoral nerve at that level. However, the AP location of the psoas muscle (and thus the lumbosacral plexus within) at L4/5 is variable. A psoas muscle lying excessively anteriorly at the L4/5 disc space may preclude safe access to the L4/5 disc space from a lateral transpsoas approach. Lumbar spine magnetic resonance imaging (MRI) for 300 consecutive patients at the authors' institution were reviewed retrospectively. The AP distance between the ventral aspect of the thecal sac and the dorsal aspect of the psoas muscle at L4/5 was measured, as was the AP diameter of the L4/5 disc space. The dorsal aspect of the psoas muscle at L4/5 was most commonly found dorsal to the ventral aspect of the thecal sac (zone P, N= 145; 48.3%), whereas it was found at the junction of zones IV/P in 37 patients (12.3%), in zone IV in 85 patients (28.3%), in zone III in 29 patients (9.7%), and in zone II in 4 patients (1.3%). The location of the psoas muscle in relation to the L4/5 disc space is somewhat variable. In 11% of patients, the dorsal-most aspect of the psoas muscle was located within zones II or III, likely precluding safe access to the L4/5 disc space from a lateral transpsoas approach.

Injury to the Lumbar Plexus and its Branches After Lateral Fusion Procedures: ACadaver Study.

Neurologic deficits from lumbar plexus nerve injuries commonly occur in patients undergoing lateral approaches. However, it is not yet clear what types of injury occur, where anatomically they are located, or what mechanism causes them. We aimed to study 1) the topographic anatomy of lumbar plexus nerves and their injuries in human cadavers after lateral transpsoas approaches to the lumbar spine, 2) the structural morphology of those injuries, and 3) the topographic anatomy of the lumbar plexus throughout the mediolateral approach corridor. Fifteen adult fresh frozen cadaveric torsos (26 sides) underwent lateral approaches (L1-L5) by experienced lateral spine surgeons. The cadavers were subsequently opened and the entire plexus dissected and examined for nerve injuries. The topographic anatomy of the lumbar plexus and its branches, their injuries, and the morphology of these injuries were documented. Fifteen injuries were found with complete or partial nerve transections (Sunderland IV and V). Injuries were found throughout the mediolateral approach corridor. At L1/2, the iliohypogastric, ilioinguinal, and subcostal nerves were injured within the psoas major muscle, the retroperitoneal space, or the outer abdominal muscles and subcutaneous tissues. Genitofemoral nerve injuries were found in the retroperitoneal space. Nerve root injuries occurred within the retroperitoneal space and psoas muscle. Femoral nerve injuries were found only within the psoas major muscle. No obturator nerve injuries occurred. Lateral approaches can lead to structural nerve damage. Knowledge of the complex plexus anatomy, specifically its mediolateral course, is critical to avoid approach-related injuries.

Anterior Column Realignment has Similar Results to Pedicle Subtraction Osteotomy in Treating Adults with Sagittal Plane Deformity.

Anterior column realignment (ACR) is a minimally invasive surgical technique used for the correction of adult sagittal plane deformity. ACR is performed via a minimally invasive lateral transpsoas approach with anterior longitudinal ligament release and hyperlordotic cage placement. The objective of this study was to compare radiographic outcomes and complications in patients treated by ACR or Pedicle subtraction osteotomy (PSO). Patients who underwent ACR were matched with patients from a retrospective PSO dataset, by pelvic incidence, lumbar lordosis, and thoracic kyphosis. Inclusion criteria included pelvic incidence and lumbar lordosis mismatch > 10°, pelvic tilt > 25°, and/or C7 sagittal vertical axis >5 cm, and minimum 1-year follow-up. All (n= 17) patients who underwent ACR underwent second-stage open posterior instrumented fusion. There were no differences in baseline demographic or radiographic parameters. Both groups were found to have significant improvement from preoperative to final follow-up for lumbar lordosis, T1 spinopelvic inclination, and T1 pelvic angle. Pelvic tilt did not improve with PSO (31° to 28°) at final follow-up but did improve in ACR group (34° to 25°). No differences were identified at 3-month or final follow-up for lumbar lordosis (51° vs. 47°), pelvic tilt (25° vs. 28°), and T1 pelvic angle (23° vs. 24°). The group undergoing PSO achieved greater T1 spinopelvic inclination correction (8° vs. 1.9°). Patients who underwent ACR had significantly less estimated blood loss than patients who underwent PSO (1.6 vs. 3.6 L, respectively), but no difference in the overall major complication rates was found (35.3% vs. 41.2%, respectively). ACR achieved similar radiographic results as PSO in a matched cohort with significantly less estimated blood loss and similar overall complication rate.

Lateral Transpsoas Approach to the Lumbar Spine and Relationship of the Ureter: Anatomic Study with Application to Minimizing Complications.

Complications from lateral lumbar interbody fusion procedures range from neurologic deficits to organ and blood vessel injuries. Injury to the ureter has been reported though uncommon. The present study was performed to elucidate the anatomic relationship of the ureter to this surgical approach. Eight adult cadavers (16 sides) were placed in the full lateral position, and the distal ureter was cannulated with a metal wire that was passed up to the kidney. Fluoroscopy was used to establish the position of the ureter in relation to the bony anatomy in this region. In the lumbar region, there was a posterior to anterior course of the left and right ureter. From the direct lateral position, the ureter was found to lie at or posterior to the anterior edge of the lumbar vertebral bodies. On 87.5% of sides, the ureter was on average 2.5 cm posterior to the anterior border of the vertebral bodies at L2, 3 cm posterior at L3, 1.0 cm posterior at L4, and on the margin of the anterior vertebral bodies at L5. In general, the ureter, from a lateral perspective, crossed the posterior third of the upper lumbar vertebrae, approached the middle third at L3, and reached the anterior third at L4/L5 before descending into the pelvis. Owing to the proximity of the ureter to the lumbar vertebral bodies, it is imperative to verify that this structure is not in the surgical trajectory during lateral lumbar interbody fusion procedures if injury is to be avoided.

Anatomy of psoas muscle innervation: Cadaveric study.

Hip flexion weakness is relatively common after lateral transpsoas surgery. Persistent weakness may result from injury to the innervation of the psoas major muscles (PMMs); however, anatomical texts have conflicting descriptions of this innervation, and the branching pattern of the nerves within the psoas major, particularly relative to vertebral anatomy, has not been described. The authors dissected human cadavers to describe the branching pattern of nerves supplying the PMMs. Sixteen embalmed cadavers were dissected, and the fine branching pattern of the innervation to the PMM was studied in 24 specimens. The number of branches and width and length of each branch of nerves to the PMMs were quantified. Nerve branches innervating the PMMs arose from spinal nerve levels L1-L4, with an average of 6.3 ± 1.1 branches per muscle. The L1 nerve branch was the least consistently present, whereas L2 and L3 branches were the most robust, the most numerous, and always present. The nerve branches to the psoas major commonly crossed the intervertebral (IV) disc obliquely prior to ramification within the muscle; 76%, 80%, and 40% of specimens had a branch to the PMM cross the midportion of the L2-3, L3-4, and L4-5 IV discs, respectively. The PMMs are segmentally innervated from the L2-L4 ventral rami branches, where these branches course obliquely across the L2-3, L3-4, and L4-5 IV discs. Knowledge of the mapping of nerve branches to the PMMs may reduce injury and the incidence of persistent weak hip flexion during lateral transpsoas surgery. Clin. Anat. 30:479-486, 2017. © 2017 Wiley Periodicals, Inc.

Anatomical evaluation of lumbar nerves using diffusion tensor imaging and implications of lateral decubitus for lateral transpsoas approach.

Recently, lateral interbody fusion (LIF) has become more prevalent, and evaluation of lumbar nerves has taken on new importance. We report on the assessment of anatomical relationships between lumbar nerves and vertebral bodies using diffusion tensor imaging (DTI). Fifty patients with degenerative lumbar disease and ten healthy subjects underwent DTI. In patients with lumbar degenerative disease, we studied nerve courses with patients in the supine positions and with hips flexed. In healthy subjects, we evaluated nerve courses in three different positions: supine with hips flexed (the standard position for MRI); supine with hips extended; and the right lateral decubitus position with hips flexed. In conjunction with tractography from L3 to L5 using T2-weighted sagittal imaging, the vertebral body anteroposterior span was divided into four equally wide zones, with six total zones defined, including an anterior and a posterior zone (zone A, zones 1-4, zone P). We used this to characterize nerve courses at disc levels L3/4, L4/5, and L5/S1. In patients with degenerative lumbar disease, in the supine position with hips flexed, all lumbar nerve roots were located posterior to the vertebral body centers in L3/4 and L4/5. In healthy individuals, the L3/4 nerve courses were displaced forward in hips extended compared with the standard position, whereas in the lateral decubitus position, the L4/5 and L5/S nerve courses were displaced posteriorly compared with the standard position. The L3/4 and L4/5 nerve roots are located posterior to the vertebral body center. These were found to be offset to the rear when the hip is flexed or the lateral decubitus position is assumed. The present study is the first to elucidate changes in the course of the lumbar nerves as this varies by position. The lateral decubitus position or the position supine with hips flexed may be useful for avoiding nerve damage in a direct lateral transpsoas approach. Preoperative DTI seems to be useful in evaluating the lumbar nerve course as it relates anatomically to the vertebral body.

Early experience with lateral lumbar total disc replacement: Utility, complications and revision strategies

Lumbar total disc replacement (TDR) is an alternative to interbody fusion for the treatment of symptomatic degenerative disc disease. Traditionally, lumbar TDR is performed via an anterior retroperitoneal approach with regional risks of vascular and visceral injury. The direct lateral retroperitoneal, transpsoas approach avoids mobilisation of the great vessels and preserves the anterior longitudinal ligament, thereby maintaining physiological limits on motion. This study aimed to (i) report one site’s early experience with lateral lumbar TDR and (ii) provide case examples illustrating the utility, complications and revision strategies of the XL-TDR device. Data were collected prospectively on the first 12 consecutive patients treated with XL-TDR. Patient outcomes included pain (VAS), disability (ODI), and quality of life (SF-36 PCS and MCS). Mean follow-up was 27.5months (range 18–48months). Patients had significant improvements in back (74%) and leg (50%) pain, ODI (69%), PCS (50%) and MCS (39%) (P<0.05). Two patients had early prosthesis dislocation due to prosthesis undersizing. The same skin incision was used to retrieve the XL-TDR and perform salvage lateral lumber interbody fusion, with solid fusion by 12months. Lumbar TDR using the XL-TDR via a lateral transpsoas muscle-splitting approach is a minimally invasive alternative to anterior retroperitoneal exposures for motion preservation. Correct sizing of the XL-TDR and complete contralateral annulectomy with annulus box cutters mitigates the risk of lateral dislocation. Revision surgery for lateral dislocation of the XL-TDR is more straightforward compared to anterior TDR dislocation.

Design and biomechanical test of a new lateral lumbar intervertebral cage-plate complex instrument

Objective To design a new minimally invasive lateral transpsoas lumbar intervertebral cage-plate complex instrument and evaluate its biomechanical characteristics. Methods The 18 fresh calf lumbar specimens simulated by one-level extreme lateral interbody fusion (XLIF) were randomly divided into three groups as follows: standalone XLIF cage in group A, standalone XLIF cage combined with posterior bilateral pedicle screw fixation in group B, and lateral lumbar intervertebral cage-plate complex instrument in group C. The test states included intactness and solid fixation. The range of motion (ROM) of fusion segment was recorded and comparisons were performed between different simulated constructs in flexion, extension, lateral bending and rotation. Results The three fixation systems were all able to stabilize the surgical segments. The ROM of surgical segment of new lateral lumbar intervertebral cage-plate complex instrument was (2.00±0.28)°, (1.31±0.69)°, (2.17±0.69)°, (2.91±1.12)° respectively, and reduced to 63%, 63%, 45% and 47% of the intact level in flexion, extension, lateral bending and rotation. Apart from the ROM of flexion (P=0.000) and extension (P=0.026), there was no significant difference in ROM between group B and group C. Conclusion The new lateral lumbar intervertebral cage-plate complex instrument can effectively afford a better biomechanical stability of lumbar vertebrae than the standalone XLIF cage in extension, lateral bending and rotation, while it can reduce less ROM in flexion and extension than standalone cage in combination with posterior internal fixation. Key words: Lumbar vertebrae; Biomechanics; Intervertebral fusion cage; Spinal fusion

Minimally invasive lateral trans-psoas approach for tuberculosis of lumbar spine

Minimally invasive lateral trans-psoas approach for tuberculosis of lumbar spine

The role of anterior interbody fusion (ALIF and XLIF with anterior column release) in the surgical management of adult spinal deformity

Anterior interbody fusions are commonly used in the treatment of adult spinal deformity. The addition of anterior fusions to posterior constructs offers increased construct stability, improved fusion rates, and better lordosis restoration. The anterior column is most commonly accessed by the anterior retroperitoneal approach, in which the anterior longitudinal ligament is resected, or by the lateral transpsoas approach, which offers the ability to either leave the anterior longitudinal ligament intact or resect it as part of anterior column realignment. Complications are mostly approach-related and include vascular, visceral, and neurological injury.

The Potentially Fatal Ogilvie's Syndrome in Lateral Transpsoas Access Surgery: A Multi-Institutional Experience with 2930 Patients.

Ogilvie's syndrome (OS) is a relatively uncommon pathology characterized by significant colonic dilation in the absence of mechanical obstruction. If unrecognized and untreated, cecal perforation resulting in a mortality rate of 25%-71% may occur. It is a potentially underdiagnosed condition in the lateral transpsoas approach population because of its uncommon nature and imitation of other well-known pathologies. Two thousand nine hundred and thirty patients from 6 separate institutions were retrospectively reviewed since 2007 and screened for OS. All patients underwent a minimum of single-level lateral transpsoas fusion. Diagnostic criteria included signs of a postoperative paralytic ileus combined with abdominal computed tomography showing a cecal diameter greater than 9 cm. Treatment modalities and outcomes were recorded. Eight cases (0.22%) of OS were diagnosed at 6 separate institutions. Most institutions recorded more than 350 lateral access procedures. Four cases were initially diagnosed as a routine postoperative ileus; however, they failed conservative therapy and underwent abdominal CT imaging. Neostigmine treatment was required for 1 patient in the intensive care unit setting, and 3 patients were managed conservatively without complications. Four other patients demonstrated bowel perforation at least 48 hours after surgery and required laparotomy with diversion ileostomy. Ogilvie's syndrome is a rare but potentially fatal complication that can mimic a postoperative ileus. It is likely underdiagnosed in the lateral transpsoas approach population because of its uncommon nature and a high index of suspicion should remain. Neostigmine can be administered safely under close observation with immediate and successful outcomes. Patients with perforation require urgent laparotomy and primary repair.

Anterior to psoas (ATP) fusion of the lumbar spine: evolution of a technique facilitated by changes in equipment.

Lateral interbody cages have been proven useful in spinal fusions. Spanning both lateral cortical rims while sparing the Anterior Longitudinal Ligament, the lateral interbody cages restore and maintain disc height while adding stability prior to supplemental fixation. The standard approach for their insertion is by a 90-degree lateral transpsoas method. This is relatively bloodless compared to other techniques although has its limitations, requiring neuro-monitoring and being, at times, very difficult at L4/5 due to iliac crest obstruction or an anterior plexus position. An oblique approach, with the patient in lateral decubitus, passes anterior to the iliac crest, retroperitoneal, and being anterior to psoas, eliminates the need for neuro-monitoring. Twenty-one consecutive patients underwent surgery for a total of 32 levels instrumented with the ATP technique. Mean age at the time of surgery was 62.4±7.4 years. There was a 6 months minimum clinical follow up, with imaging to assess fusion, at 6 and 12 months. Indications included symptomatic degenerative lumbar spondylosis +/- spondylolisthesis, leg and back pain. All patients were assessed with the Oswestry Disability Index (ODI), Visual Analog Scale 100 mm for back pain (VASb) and for leg pain (VASl) preoperatively, at 3, 6 and 12 months. Last follow-up was at 12 months for 9 patients and the rest had 6 months follow up. Statistical analysis showed significance for the results in ODI, VASb and VASl with improvement in all components except for one patient with worsening VASl. Eight patients had complications related to surgery which were still present at last follow-up including moderate weakness of hip flexion and EHL weakness. Lateral cutaneous nerve (LCN) palsy on the side of the approach was also seen as well as sympathectomy effect related to the mobilization of the sympathetic trunk. One patient, who also suffered from multiple sclerosis, experienced psoas abscess 3 months post op that required drainage. The left sided anterior to psoas approach offers the most natural corridor to the disc space. The novel instruments and method described here allows insertion of large lateral cages between L2 to L5, without the problems associated with the transpsoas approach, particularly at L4/5.

Technical description of oblique lateral interbody fusion at L1–L5 (OLIF25) and at L5–S1 (OLIF51) and evaluation of complication and fusion rates

Background ContextThe oblique lateral interbody fusion (OLIF) procedure is aimed at mitigating some of the challenges seen with traditional anterior lumbar interbody fusion (ALIF) and transpsoas lateral lumbar interbody fusion (LLIF), and allows for interbody fusion at L1–S1. PurposeThe study aimed to describe the OLIF technique and assess the complication and fusion rates. Study DesignThis is a retrospective cohort study. Patient SampleThe sample is composed of 137 patients who underwent OLIF procedure. Outcome MeasuresThe outcome measures were adverse events within 6 months of surgery: infection, symptomatic pseudarthrosis, hardware failure, vascular injury, perioperative blood transfusion, ureteral injury, bowel injury, renal injury, prolonged postoperative ileus (more than 3 days), incisional hernia, pseudohernia, reoperation, neurologic deficits (weakness, numbness, paresthesia), hip flexion pain, retrograde ejaculation, sympathectomy affecting lower extremities, deep vein thrombosis, pulmonary embolism, myocardial infarction, pneumonia, and cerebrovascular accident. The outcome measures also include fusion and subsidence rates based on computed tomography (CT) done at 6 months postoperatively. MethodsRetrospective chart review of 150 consecutive patients was performed to examine the complications associated with OLIF at L1–L5 (OLIF25), OLIF at L5–S1 (OLIF51), and OLIF at L1–L5 combined with OLIF at L5–S1 (OLIF25+OLIF51). Only patients who had at least 6 months of postoperative follow-up, including CT scan at 6 months after surgery, were included. Independent radiology review of CT data was performed to assess fusion and subsidence rates at 6 months. ResultsA total of 137 patients underwent fusion at 340 levels. An overall complication rate of 11.7% was seen. The most common complications were subsidence (4.4%), postoperative ileus (2.9%), and vascular injury (2.9%). Ileus and vascular injuries were only seen in cases including OLIF51. No patient suffered neurologic injury. No cases of ureteral injury, sympathectomy affecting the lower extremities, or visceral injury were seen. Successful fusion was seen at 97.9% of surgical levels. ConclusionsOblique lateral interbody fusion is a safe procedure at L1–L5 as well as L5–S1. The complication profile appears acceptable when compared with LLIF and ALIF. The oblique trajectory mitigates psoas muscle and lumbosacral plexus-related complications seen with the lateral transpsoas approach. Furthermore, there is a high fusion rate based on CT data at 6 months.

55. Minimally invasive lateral transpsoas approach: Comorbidity in our cases

The minimally invasive lateral transpsoas approach to the lumbar spine is a valid and recent alternative to interbody placement at levels L1–L5 in the setting of degenerative disc disease, spondylolisthesis, and scoliotic or kyphotic deformity. The benefits over traditional open surgery include reduced blood loss, decreased postoperative pain and narcotics use, shorter hospital length of stay, faster recover and quicker return to work and normal activity. The most common complications following this procedure include anterior thight numbness, lower extremity radiculopathy with weakness, iliopsoas and/or quadriceps weakness, and pseudoarthrosis. Papanastassiou et al. reported on two patients unusual complication of controlateral femoral nerve compression. The direct lateral approach requires the patient to be in lateral decubitus position. The technique utilizes specialized retractors allowing for direct visualization of the surgical approach corridor. Electrophysiological monitoring is believed to be critical in localizing the lumbosacral plexus during positioning of the retractor system. In according to the recent guidlines SINC-NeuroSIAARTI-SINCh, Intraoperative Stimulation (Clip and Probe), Free-Run EMG, PES and PEM of the both Legs are used. We monitorized 21 patients: 5 pazients had a postoperative temporary weakness of the Iliopsoas muscle, and only one patient with impaired diabete had a post operative spondilodiscitis.