Morphometric MRI Imaging Study of the Corridor for the Oblique Lumbar Interbody Fusion Technique at L1-L5

Oblique lateral interbody fusion at L5-S1: feasibility, surgical approach window, incision line, and influencing factors

PURPOSE

The primary aim of this study was to describe the feasibility, surgical approach window (SAW), and incision line (IL) for oblique lateral interbody fusion at L5-S1 (OLIF51) using computed tomography (CT). A secondary aim was to identify associations among approach characteristics and demographic and anthropometric factors.

METHODS

We performed a radiographic study of 50 male and 50 female subjects who received abdominal CT imaging. SAW was measured as the distance from the midline to the medial border of the iliac vessel. IL was measured at the skin surface corresponding to the distance between the center of the disc space and SAW lateral margin. OLIF51 feasibility was defined as the existence of at least a 1-cm SAW without retraction of soft tissues.

RESULTS

For the left side, the OLIF51 SAW and IL were 12.1 ± 4.6 and 175.1 ± 55.3 mm. For the right side, these measures were 10.0 ± 4.3 and 185.0 ± 52.5 mm. Correlations of r = 0.648 (p < 0.001) and r = 0.656 (p < 0.001) were observed between weight and IL on the left and right sides, respectively. OLIF51 was not feasible 23% of the time.

CONCLUSION

To our knowledge, this is the largest CT study to determine the feasibility of performing an OLIF51. Without the use of retraction, OLIF51 is not feasible 23% of the time. Left-sided OLIF51 allows for a larger surgical approach window and smaller incision compared to the right side. Larger incisions are required for adequate surgical exposure in patients with higher weight.

An Expanded Surgical Corridor of Oblique Lateral Interbody Fusion at L4-5: A Magnetic Resonance Imaging Study

OBJECTIVE

We introduced a new preoperative method, the "expanded surgical corridor," to evaluate the actual safety corridor, which may expand the possibility of performing oblique lateral interbody fusion (OLIF).

METHODS

Axial T2-weighted magnetic resonance images at the L4-5 disc level of 511 lumbar degenerative disease patients was evaluated. The distance between the medial edge of the left-sided psoas muscle and the major artery was measured as the conventional surgical corridor (CSc). The distance between the major vein and lumbar plexus was measured as the expanded surgical corridor (ESc).

RESULTS

The mean CSc and ESc were 13.9 ± 8.20 and 37.43 ± 10.1 mm, respectively. No surgical corridor was found in 7.05% of CSc and 1.76% of ESc, small corridor ( ≤ 1 cm) was found in 27.40% of CSc and 0.59% of ESc, moderate corridor (1-2 cm) was found in 42.07% of CSc and 1.96% of ESc, and large corridor ( > 2 cm) was found in 23.48% of CSc and 95.69% of ESc. A total of 33.83% (45 of 133) of whom were preoperatively categorized as having a limited surgical corridor by conventional measurement, underwent OLIF L4-5 successfully.

CONCLUSION

By using the ESc, only 2.35% were categorized as having a limited surgical corridor. The other 97.65% of the patients had an approachable corridor that could be successfully operated by experienced spine surgeons who employ meticulous surgical dissection and thorough understanding of the anatomical structures. The ESc may represent true accessibility to the disc space for OLIF, particularly at the L4-5 level.

Should a Narrow Corridor Be a Contraindication for Performing Oblique Lateral Interbody Fusion Procedure or Not?

STUDY DESIGN

Retrospective study.

OBJECTIVES

We investigated the effect of corridor width on the postoperative outcomes of patients who underwent the OLIF procedure.

METHODS

Patients who underwent OLIF surgery, which included L4-5, between 2015 and 2021 were retrospectively studied. The patients were divided into three groups by the width of the corridor: not more than 10 mm, between 10 and 20 mm, and 20 mm or more. We compared clinical and radiographic outcomes and complications between these groups.

RESULTS

A total of 81 patients were included. There were no significant differences in VAS leg and back pain scores, ODI scores, or complications between each group. The radiographic findings, including cage position, anterior and posterior disc height, segmental Cobb angle, and foraminal height, also showed no significant differences between each group. The only radiographic finding that showed a significant difference between each group was the angle of the cage. We found significantly less degree of angle in the wider than 20 mm group when compared to the other two groups. (P-value = .01). There was no recorded incidence of major vascular complications.

CONCLUSIONS

The width of oblique corridor does not affect clinical outcomes, complications, or radiographic findings, including position of the cage, anterior and posterior disc height, segmental angle, and foraminal height after OLIF procedure, including L4-5 level. Thus, the OLIF procedure can be performed safely even in patients with limited oblique corridors, especially at L4-5.

Antepsoas Approaches to the Lumbar Spine

Lumbar interbody fusion (LIF) is a well-established approach in treating spinal deformity and degenerative conditions of the spine. Since its inception in the 20th century, LIF has continued to evolve, allowing for minimally invasive approaches, high fusion rates, and improving disability scores with favorable complication rates. The anterior to the psoas (ATP) approach utilizes a retroperitoneal pathway medial to the psoas muscle to access the L1-S1intervertebral disc spaces. In contrast to the transpsoas arppoach, its primary advantage is avoiding transgressing the psoas muscle and the contained lumbar plexus, which potentially decreases the risk of injury to the lumbar plexus. Avoiding transgression of the psoas may minimize the risk of transient or permanent neurological deficits secondary to lumbar plexus injury. Indications for ATP approaches may expand as it is shown to be a safe and effective method of achieving spinal arthrodesis.

CT-based analysis of oblique lateral interbody fusion from L1 to L5: location of incision, feasibility of safe corridor approach, and influencing factors

PURPOSE

The primary aim was to measure the safe corridor (SC), surgical incision anterior margin (AM), and posterior margin (PM) for OLIF bilaterally from L1 to L5. The secondary aim was to determine the feasibility of approach via the SC. The tertiary aim was to analyze the influence of demographic and anthropometric factors on OLIF parameters.

METHODS

We performed a radiographic analysis of 100 subjects who received an abdominal CT. Measurements of the AM, PM, and SC were obtained as well as patient age, sex, height, weight, and BMI. The intraclass correlation coefficient was used to evaluate interrater reliability. To assess associations among variables, Pearson's correlation tests and multivariate linear regression models were constructed. Sex differences were analyzed using Student's t tests.

RESULTS

At L1-2, L2-3, L3-4, and L4-5, the PM was 6.6, 8.2, 9.4, and 10.2 cm on the left side and 7.2, 7.7, 8.8, and 9.5 cm on the right side in relation to the disk space center. The SC was less than 1 cm 1%, 3%,3%, and 18% of the time on the left side, and 15%, 12%,29%, and 60% on the right side. None of the anthropometric factors demonstrated a strong correlation with incision location. SC was larger on the left side. Interrater ICC was .934.

CONCLUSIONS

This study is the first to provide guidelines on the appropriate location of the incision line during OLIF based on SC from L1 to L5. SC measurements do not vary by sex. OLIF is more feasible via a left-sided approach.

A comparative morphometric analysis of operative windows for performing OLIF among normal and deformity group in lower lumbar spine

PURPOSE

To assess the radiological morphometric parameters of OLIF surgical technique in lower lumbar spine among normal and in patients with adult degenerative spine (levoscoliosis and dextroscoliosis).

METHOD

Standing AP radiographs and MRI in supine position were taken. Patients were divided into 3 groups based on Cobbs' angle into normal, levo and dextro scoliosis. Moros classification was used to calculate bare window (BW), vascular window (VW), Psoas window (PW), psoas major height (pmh) and width (pmw) at lower lumbar levels and measurements were done on PACS.

RESULTS

Seventy five patients (25 in each group) were assessed. BW has trend from L2-L3 > L3-L4 > L4-L5 in dextro and levoscoliosis. PW has trend from L3-L4 > L2-L3 > L4-L5 in levoscoliosis and normal group. VW has trend from L4-L5 > L3-L4 > L2-L3 in dextro and levoscoliosis; pmw has trend from L4-L5 > L3-L4 > L2-L3 in Levo and dextroscoliosis; pmh has trend from L4-L5 > L3-L4 > L2-L3 in levoscoliosis and normal group.

CONCLUSION

BW was noted to be highest at L3-4, lowest at L4-5 in normal group. VW was constant, BW showed a reverse trend with PW across all the levels. Though levoscoliosis group of patients had significantly higher BW, psoas retraction issues are to be kept in mind in view of anatomically taught psoas.

Anterior Column Realignment Using an Anterior-To-Psoas Approach: A Radiographic-Anatomic Feasibility Study at L1-L5

STUDY DESIGN

Cross-sectional radioanatomic study.

OBJECTIVE

To determine the feasibility of performing an anterior column realignment (ACR) using an anterior-to-psoas (ATP) approach at L1-L5.

METHODS

Axial magnetic resonance images (MRI) of the L1-L5 disc levels obtained at a single institution were obtained and analyzed. The feasibility of performing an ACR was assessed using a combination of the size of the left oblique corridor (OC), the psoas morphology using the modified Moro classification, and the anterior disc edge to great vessel distance.

RESULTS

Three hundred MRI studies obtained from 300 patients were included. All patients had a measurable left OC at the L1-L4 levels. Twenty patients (6.7%) had no measurable OC at the L4-L5 level. According to the modified Moro's classification, a high-rising psoas was seen in 4 patients (1.3%) at the L3-L4 level and 57 patients (19.0%) at the L4-L5 level. An ALL release was considered high risk due to no measurable space between the anterior disc edge and the great vessels in 54 patients (18.0%) at the L1-L2 level, 39 patients (13.0%) at the L2-L3 level, 119 patients (39.7%) at the L3-L4 level, and 226 patients (75.3%) at the L4-L5 level.

CONCLUSION

ACR using an ATP approach is the most radioanatomically feasible at L2-L3. The L4-L5 level has the highest risk with regards to both the ATP approach and the ALL release for an ACR due to high rates of unmeasurable left OC and space between the anterior disc edge and the great vessels.

Characteristics and hotspots of the 50 most cited articles in the field of pre-psoas oblique lumbar interbody fusion

PURPOSE

In the past decade, the field of pre-psoas oblique lumbar interbody fusion (OLIF) has developed rapidly, and with it, the literature on OLIF has grown considerably. This study was designed to analyze the top 50 articles in terms of the number of citations through bibliometric research to demonstrate the research characteristics and hotspots of OLIF.

METHOD

Searching the Web of Science database yielded the 50 most cited publications in the OLIF field as of July 10, 2022. The publications were ranked according to the number of citations. The following sources were evaluated: the year of publications, the number of citations, authors, countries, institutions, journals, research topics, and keyword hotspots.

RESULTS

The most productive period was from 2017 to 2020, with 41 articles. The number of citations varied from 10 to 140, with an average of 35.52, and 1,776 citations were found. World Neurosurgery published the most articles (12), China produced the most articles (16), and the Catholic University of Korea produced the most studies (6). The corresponding author who produced the most articles was J.S. Kim (5), and the first author who produced the most publications was S. Orita (3). The main research topics were anatomical morphology, surgical techniques, indications, outcomes, and complications. The top 10 most cited keywords were "complications," "decompression," "spine," "surgery," "outcomes," "transpsoas approach," "spondylolisthesis," "anterior," "disease," and "injury."

CONCLUSIONS

Certain articles can be distinguished from others using citation analysis as an accurate representation of their impact due to their long-term effectiveness and peer recognition. With these publications, researchers are provided with research priorities and hotspots through influential literature in the field of OLIF.

The Antepsoas (ATP) Surgical Corridor for Lumbar and Lumbosacral Arthrodesis: A Radiographic, Anatomic, and Surgical Investigation

STUDY DESIGN

Retrospective review of prospectively collected data.

OBJECTIVE

To investigate the size of prepsoas surgical corridors, developed between the iliopsoas and prespinal vessels, at all disk levels between L1 and S1 granted by left and right lateral antepsoas (ATP) approaches. Secondary aims include evaluation of presurgery radiographic prepsoas windows between L1 and S1 with respect to the intraoperative findings.

SUMMARY OF BACKGROUND DATA

The ATP technique is an evolving alternative to the transpsoas and direct anterior exposures for lumbar fusion. However, the vascular morphometric data of the ATP approach remain underexplored, especially at L5-S1.

MATERIALS AND METHODS

Patients indicated for ATP lumbar-lumbosacral fusion between September 2018 and February 2020 were enrolled (n=121). Data were collected prospectively, including the following (in mm): intraoperative manual measurements of the premobilization psoas-vessel (pre-PV) window, the final postmobilization psoas-vessel (post-PV) window, and the preoperative radiographic psoas-to-vessel distance at the respective studied disk levels.

RESULTS

A total of 121 patients (75 female, mean age: 55.3 yr, 81.8% right-sided approach) underwent a total of 279 levels of spinal fusion. Irrespective of the ATP access laterality, we noted ample postmobilization psoas-vessel (post-PV differential) corridors: largest at L4-L5 (36-38 mm) followed by L5-S1 (31-35 mm), L3-L4 (32-33 mm), L2-L3 (28-30 mm), and L1-L2 (20-24 mm). Similarly, the relative increases of the psoas-vessel corridors (post-PV and pre-PV differentials, averaged: 31 mm at L5-S1, 32 mm at L4-L5, 26 mm at L3-L4, 25 mm at L2-L3, and 14 mm at L1-L2) were also significant in both lateral approaches. In right flank approaches, the right vascular structures projected more dorsally compared with left-sided vasculature ( P <0.05).

CONCLUSION

The ATP access offers generous bilateral prepsoas surgical windows to L1-S1 intervertebral disks, allowing for a safe anterior column release, decompression, instrumentation, and fusion.

Pearls and Pitfalls of Oblique Lateral Interbody Fusion: A Comprehensive Narrative Review

Lumbar degenerative disease is a common problem in an aging society. Oblique lateral interbody fusion (OLIF) is a minimally invasive surgical (MIS) technique that utilizes a retroperitoneal antepsoas corridor to treat lumbar degenerative disease. OLIF has theoretical advantages over other lumbar fusion techniques, such as a lower risk of lumbar plexus injury than direct lateral interbody fusion (DLIF). Previous studies have reported favorable clinical and radiological outcomes of OLIF in various lumbar degenerative diseases. The use of OLIF is increasing, and evidence on OLIF is growing in the literature. The indications for OLIF are also expanding with the help of recent technical developments, including stereotactic navigation systems and robotics. In this review, we present current evidence on OLIF for the treatment of lumbar degenerative disease, focusing on the expansion of surgical indications and recent advancements in the OLIF procedure.

STUDY OF THE DIAMETER OF THE OBLIQUE CORRIDOR IN LATERAL DECUBITUS AND DORSAL DECUBITUS: RADIOLOGICAL STUDY

ABSTRACT Introduction: Degenerative intervertebral disc disease and its impact on quality of life when associated with sagittal misalignmentis a current topic in the literature. The technique known as OLIF derives from the need to use anterior cage stop romote stabilization of the affected segment, indirect decompression, restoration of segmental lordosis, and sagittal balance. Methods: Single-center, non-randomized, comparative, observational study. The following variables were measured using magnetic resonance imaging of the lumbar spine in dorsal and lateral decubitus, establishing a comparison between the size of the OLIF corridor in the L3L4 and L4L5 segments, as well as a comparison of corridor size between the different positions. Results: There was no difference incorridor size in the comparison between decubitus. However, when the L3L4 and L4L5 levels were compared, there was a significant difference in the size of the corridor in both the lateral and dorsal positions. Conclusion: The present study did not show any difference between the size of the OLIF corridor in L3L4 and L4L5 in the different decubitus, suggesting that thee valuation of the corridor in convention al magnetic resonance images appearstobe safe andreflects the actual size when positio ned for performing the OLIF technique. Level of evidence III; Retrospective study.

Analysis of Hidden Blood Loss and its Risk Factors in Oblique Lateral Interbody Fusion Surgery

STUDY DESIGN

This was a retrospective study.

OBJECTIVE

The objective of this study was to evaluate the volume of hidden blood loss (HBL) and analyze its influential factors in single level oblique lateral interbody fusion (OLIF) surgery.

SUMMARY OF BACKGROUND DATA

OLIF is a minimally invasive spine surgery and is increasingly used to treat lumbar degenerative disk diseases. It is generally believed that there is less bleeding during OLIF. However, HBL during the perioperative period is commonly ignored.

MATERIALS AND METHODS

From January 2018 to December 2019, a total of 70 patients underwent single level OLIF surgery were retrospectively reviewed. The values of preoperative and postoperative hematocrit (Hct) were recorded to reckon HBL in accordance with Gross formula. The influential factors included sex, age, height, weight, body mass index, hypertension, diabetes mellitus, American Society of Anesthesiologists classification, disease etiology, surgery type, operative time, surgical corridor distance, psoas cross-sectional area, thickness of abdominal wall soft tissue, coagulation panel value, platelet count, values of Hct and hemoglobin, and intraoperative blood loss. Independent sample t test, Pearson correlation, Spearman correlation, and multivariate linear regression analysis were performed to investigate the risk factors related to HBL.

RESULTS

The average volume of HBL was 809 mL and the average hemoglobin loss was 27.1 g/L in OLIF procedure. Multiple linear regression analysis revealed that thickness of abdominal wall soft tissue was the independent risk factor for HBL (P=0.008). Whereas age (P=0.414), activated partial thromboplastin time (P=0.314), preoperative value of Hct (P=0.854), disease etiology (P=0.362), operative time (P=0.389), and intraoperative blood loss (P=0.912) were not statistically associated with HBL.

CONCLUSIONS

HBL was substantial and the average volume of HBL was 809 mL in single level OLIF surgery. The thickness of abdominal wall soft tissue was the risk factor of HBL. Accurate assessment of HBL can prevent perioperative complications and ensure patients' safety.

Surgical safe zones for oblique lumbar interbody fusion of L1-5: A cadaveric study

To evaluate the operating range and morphology of the surgical safe zone for oblique lumbar interbody fusion (OLIF). Twenty embalmed full-torso cadaveric specimens were dissected. The oblique corridor and the distance between adjacent lumbar arteries were measured in a static state and with psoas major retraction. The morphology and size of the safe zone for OLIF and the location of the lumbar sympathetic trunk were also recorded. The oblique corridor of the L1-L5 segments was significantly greater in the retracted state than in the static state (p < 0.05). With psoas major retraction, the distances between adjacent lumbar arteries at L1-4 were significantly greater (p < 0.05) than those in the static state. The lumbar sympathetic trunk is just located in the safe zone and travels downward adjacent to the psoas major. The shape of the safe zone for OLIF was approximately an oblique upward parallelogram at L1/2 and L2/3, an isosceles trapezoid at L3/4, and an irregular quadrangle or triangle at L4/5. The safe zone for OLIF at L1/2, L2/3, and L3/4 was significantly larger during retraction than in the static state (p < 0.05). On the lateral side of the lumbar spine there is a natural surgical safe zone for OLIF, which can provide a sufficient operating space. The safe zone has a certain morphological pattern in L1-5 segments and psoas major retraction can significantly enlarge it.

Assessment of 3D Lumbosacral Vascular Anatomy for OLIF51 by Non-Enhanced MRI and CT Medical Image Fusion Technique

Study design: Prospective study. Objective: Medical image fusion can provide information from multiple modalities in a single image. The present study aimed to determine whether three-dimensional (3D) lumbosacral vascular anatomy could be adequately portrayed using a non-enhanced CT–MRI medical image fusion technique. Summary of Background Data: Lateral lumbar interbody fusion has gained popularity for the surgical treatment of adult spinal deformity (ASD). Oblique lumbar interbody fusion at L5–S1 (OLIF51) is receiving considerable attention as a method of creating good L5–S1 lordosis. Access in OLIF51 requires evaluation of the vascular anatomy in the lumbosacral region. Conventional imaging modalities need a contrast medium to describe the vascular anatomy. Methods: Participants comprised 15 patients with ASD or degenerative lumbar disease who underwent corrective surgery at our hospital between January 2020 and June 2021. A 3D vascular image with bony structures was obtained by fusing results from MRI and CT. We processed the merged image and measured the distance between left and right common iliac arteries and veins at two levels: the lower end of the L5 vertebral body (Window A) and the upper end of the S1 vertebral body (Window B). Results: The mean sizes of Window A and Window B were 29.7 ± 10.7 mm and 36.9 ± 10.3 mm, respectively. The mean distance from the bifurcation to the lower end of the L5 vertebra was 23.7 ± 10.9 mm. Coronal deviation of the bifurcation was, from center to left, 12.6 ± 12.3 mm, and the distance from the center of the L5 vertebral body to the bifurcation was 0.79 ± 7.3 mm. Only one case showed a median sacral vein (6.7%). Clinically, we performed OLIF51 in 12 of the 15 cases (80%). Conclusion: Evaluating 3D lumbosacral vascular anatomy using a non-enhanced MRI and CT medical image fusion technique is very useful for OLIF51, particularly for patients in whom the use of contrast medium is contraindicated.

MRI-Based Morphometric Study Regarding Operative Windows of Oblique Lumbar Interbody Fusion in Indian Population

BACKGROUND

The novel Oblique lumbar interbody fusion [OLIF] technique has been proposed as a solution to approach related complications of anterior lumbar interbody fusion [ALIF] and lateral lumbar interbody fusion [LLIF]. There exists no study concerning morphological evaluation of retroperitoneal oblique corridor for the Oblique lumbar interbody fusion (OLIF) technique in the Indian population. The aim of our study was (a) to measure magnetic resonance imaging (MRI) based anatomic parameters concerning OLIF operative windows from L2-L3 to L4-L5 level (b) to determine the feasibility of this technique following MRI-based morphometric evaluation in the Indian population.

MATERIAL AND METHODS

We did retrospective MRI analysis of 307 consecutive patients following our exclusion criteria. Bare window, psoas major window and psoas major width were measured from axial T2 MRI image taken at mid disc level from L2-L3 to L4-L5 levels.

RESULTS

The mean bare window size was largest at L2-L3 (1.39 cm) level followed by L3-L4 and L4-L5 level (1.28 and 0.62 cm respectively), and differences between them were statistically significant (P < 0.001). Females had statistically significant larger bare windows at L2-L3 and L3-L4 level than males (P < 0.001). With increasing age, there was a significant increase in bare window size at each level (P < 0.001). The mean psoas major window (PM^O) and mean psoas major width (PM^I) were largest at L4-L5 level (PM^O = 1.27 cm, PM^I = 3.61 cm) followed by L3-L4 and L2-L3 level (L3-L4: PM^O = 1.19 cm, PM^I = 2.36 cm; L2-L3: PM^O = 0.88 cm, PM^I = 1.39 cm), and differences among each level concerning both parameters were statistically significant (P < 0.001). Both parameters (PM^O, PM^I) were significantly larger in males than females at each level (P < 0.001).

CONCLUSION

The OLIF technique is well suited for lumbar interbody fusion at L2 -L3 and L3-L4 level in the Indian population irrespective of age and sex. At L4-L5 level, overall 17.9 percent of the study population were unsuitable for this technique due to inaccessible bare window. In our opinion, this level may be better suited for OLIF approach in the elderly Indian population, especially for surgeons who are beginning to attempt this technique in their surgical practice. Preoperative MRI evaluation for the OLIF is important to assess its feasibility, as there exists significant age and gender differences in the Indian population for anatomic parameters concerning OLIF operative windows from L2-L3 to L4-L5 levels.

SUPPLEMENTARY INFORMATION

The online version contains supplementary material available at 10.1007/s43465-021-00393-7.

Oblique lumbar interbody fusion in management of lumbar degenerative spinal stenosis in Chinese population

Purpose:

The purpose of this study was to assess the outcomes of a cohort of local Chinese patients who underwent oblique lumbar interbody fusion (OLIF) surgery for lumbar degenerative diseases.

Methods:

We adopted a minimally invasive anterior approach to the lumbar spine through retroperitoneal access. In the first part of the surgery, a 3- to 5-cm left lateral incision over the abdomen was made guided by imaging. L2–L5 disc space was approached via the corridor between the left psoas muscle and the great vessels. A specially designed interbody cage filled with bone substitute was utilized for interbody fusion. In the second part of the surgery, posterior instrumentation with or without decompression, was performed in a prone position. Efficacy and safety of the surgery were studied.

Results:

A total of 60 patients with the mean age of 68 years underwent OLIF at 83 surgical levels. Their mean operative time was 79 min, and the average blood loss was 84 ml for the OLIF part. The mean length of hospital stay was 5.5 days. Based on plain computed tomography scan obtained at post-operative 6 months, successful fusion was achieved in 82 of the 83 surgical levels. The Oswestry Disability Index for low back pain had a mean reduction of 22.3% after 6 months. Specific complications observed include transient thigh pain or numbness, retroperitoneal hematoma, post-operative ileus and Bone Morphogenetic Protein (BMP) osteolysis. None of the patients experienced infection, symptomatic pseudo-arthrosis, hardware failure, vascular injury, nerve injury, ureteral injury, bowel injury, incisional hernia or death.

Conclusion:

OLIF is an effective procedure to treat lumbar spinal stenosis and spondylolisthesis with excellent fusion rate and good functional outcome. Complications specific to this procedure are not uncommon, but majority are minor and self-recovery. Proper training is required to minimize potential surgical risks.

[Research progress of ureteral injury in oblique lumbar interbody fusion]

Objective

To summarize the research progress of ureteral injury in oblique lumbar interbody fusion (OLIF).

Methods

The literature about incidence, clinical manifestations, diagnosis, and treatment of ureteral injury complications in OLIF was reviewed.

Results

OLIF surgery poses a risk of ureteral injury because its surgical approach is anatomically adjacent to the left ureter. Ureteral injuries in OLIF are often insidious and have no specific clinical manifestations. CT urography is a common diagnostic method. The treatment of ureteral injury depends on a variety of factors such as the time of diagnosis, the location and degree of injury, and the treatment methods range from endoscopic treatment to replacement reconstruction.

Conclusion

Surgeons should pay attention not to damage the ureter and find the abnormality in time during OLIF. High vigilance of abnormalities is conducive to the early diagnosis of ureteral injury. Furthermore, it is important to be familiar with ureter anatomy and gentle operation to prevent ureteral injury.

Correlation study of radiographic characteristics and operative difficulty in lateral-anterior lumbar interbody fusion (LaLIF) at the L4-5 level: a novel classification for case selection

PURPOSE

To analyze correlations between the realistic surgical difficulty of LaLIF and anatomic characteristics in radiographic images, in order to develop a simple classification to provide guiding information for case selection and evaluate the potential risks of the technique.

METHODS

Ninety-six consecutive cases who underwent LaLIF surgeries at the L4-5 level with MR T2-weighted images were analyzed. A novel classification based on the anatomic relationships among the disk, great vessels, and psoas muscle was used for grouping. Clinical outcomes and realistic surgical difficulty parameters were recorded, and comparisons were made among different types of classifications.

RESULTS

Of the 96 analyzed cases, the time of surgical exposure was significantly longer for type C than for type B, and both of these were longer than that of type A. The VAS and ODI were significantly improved at a 1-year follow-up. There was no statistically significant difference among the three types. Type C had the highest incidence of complications, while Type A had the lowest. Analyses of another 304 MRI cases obtained in outpatient clinics showed that the distribution of the three types among these cases was consistent with that of the surgical cohort.

CONCLUSION

Our novel and simple classification provides useful information for case selection. Type A provided the best indication and is most appropriate for a beginner in this technique. Type C includes the most challenging situations, which may have a high incidence of complications and require sophisticated surgical skills to achieve satisfactory outcomes and avoid approach-related complications.

Changes in the Operative Corridor in Oblique Lumbar Interbody Fusion Between Preoperative Magnetic Resonance Imaging and Intraoperative Cone-Beam Computed Tomography Using Morphometric Analysis

Background

The oblique lumbar interbody fusion or anterior-to-psoas (OLIF/ATP) technique relies on a corridor anterior to the psoas and posterior to the vasculature for lumbar interbody fusion. This is evaluated preoperatively with CT and/or MRI. To date, there have been no studies examining how intraoperative, lateral decubitus positioning may change the dimensions of this corridor when compared to preoperative imaging.

Objective

Our objective was to evaluate changes in the intraoperative corridor in the supine and lateral positions utilizing preoperative and intraoperative imaging.

Methods

We performed a retrospective analysis among patients who have undergone an OLIF/ATP approach at two tertiary care centers from 2016 to 2018 by measuring the distance between the left lateral border of the aorta or iliac vessels and anteromedial border of the psoas muscle from L1-L2 through L4-5 disc spaces. We compared this corridor between supine, preoperative MRI axial and intraoperative CT acquired in the right lateral decubitus position.

Results

Thirty-three patients, 15 of whom were female, were included in our study. The average age of the patients was 65.4 years and the average BMI was 31 kg/m². The results revealed a statistically significant increase (p<.05) in the intraoperative corridor from supine to lateral decubitus positioning at all levels. However, age, BMI, and gender had no statistically significant impact on the preoperative versus intraoperative corridor.

Conclusion

This is the first study to provide objective evidence that lateral decubitus positioning increases the intraoperative corridor for OLIF/ATP. Our study demonstrates that lateral decubitus positioning provides a more favorable corridor for the OLIF/ATP technique from L1-L5 disc levels.

The OLIF working corridor based on magnetic resonance imaging: a retrospective research

OBJECTIVE

To provide an anatomical basis for the development of oblique lumbar interbody fusion (OLIF) in Chinese patients.

METHODS

Between November 2018 and June 2019, 300 patients' lumbar MRI data were reviewed. According to the Moro system and zone method described by us, the axial view was vertically divided into 6 zones (A, I II, III, IV, P) and was horizontally divided into 4 zones (R, a, b, c, L). The locations of left psoas muscle and the major artery at L2/3, L3/4, and L4/5 levels were evaluated by the grid system. The aortic bifurcation segments will also be evaluated at the level of the vertebral body or the disc.

RESULTS

At the L2/3 level, left psoas muscle and the major artery in zone Ib were found in 28.0% of subjects, in zone IIb in 20.3%, and in zone Ic in 20.0%; at the L3/4 level, in zone Ab in 20.7% of subjects, in zone Ac in 26.0%, and in zone Ic in 11.0%; and at the L4/5 level, areas in zone Ab in 31.0% of subjects, in zone Ac in 26.0%, and in zone Ib in 11.7%. The aortic bifurcation segments were mainly at the L4 level. The zone of the left psoas muscle at all levels, the zone of the major artery at L4/5 level, and the zone of the aortic bifurcation segments had significant correlation with gender difference (P < 0.05).

CONCLUSION

The left-sided OLIF at L2-L5 disc levels can be a feasible type of surgery for lumbar interbody fusion in the majority of Chinese patients. Before the operation, in order to screen out the appropriate surgical approach, routine lumbar magnetic resonance imaging is recommended to analyze the patient's local anatomical features.

Magnetic Resonance Imaging Study of Oblique Corridor and Trajectory to L1-L5 Intervertebral Disks in Lateral Position

OBJECTIVE

This study investigated the retroperitoneal oblique corridor and trajectory of L1-L5 as the lateral surgical access to the intervertebral disks in the Chinese population and detected the potential relationship between the corridor or trajectory and vertebral parameters, including disk axis, psoas muscle, and retroperitoneal vessel.

METHODS

Seventy magnetic resonance imaging studies performed from January 2017 to January 2019 were investigated. The oblique corridor was defined as the distance between the left lateral border of the retroperitoneal vessel and the anterior border of psoas. The trajectory was defined as the distance between the retroperitoneal vessel and lumbar plexus.

RESULTS

The oblique corridor analysis to L1-L5 disks have the following mean distances: L1-2 13.36 mm, L2-3 13.36 mm, L3-4 12.37 mm, and L4-5 10.36 mm. There was no difference in the L1-L5 corridor between genders. And the position of retroperitoneal vessel was negatively correlated with the corridor width. The trajectory measurements to L1-L5 disks have the following mean distances: L1-2 27.44 mm, L2-3 30.86 mm, L3-4 30.73 mm, and L4-5 24.36 mm. Moreover, the vertebral parameters, including the disk axis and psoas muscle, were positively correlated with the trajectory width. Otherwise, the position of retroperitoneal vessel was negatively correlated with the trajectory width.

CONCLUSIONS

Compared with previous studies, the safe surgical area of the Chinese is generally smaller than that of Caucasian. The position of the retroperitoneal vessel is the vital potential to limit the corridor and trajectory. Preoperative assessment of vertebral parameters, especially vascular structure, is essential for planning surgical process.

Complications and Prevention Strategies of Oblique Lateral Interbody Fusion Technique

OBJECTIVE

To analyze the early complications and causes of oblique lateral interbody fusion, and put forward preventive measures.

METHODS

There were 235 patients (79 males and 156 females) analyzed in our study from October 2014 to May 2017. The average age was 61.9 ± 0.21 years (from 32 to 83 years). Ninety-one cases were treated with oblique lateral interbody fusion (OLIF) alone (OLIF alone group) and 144 with OLIF combined with posterior pedicle screw fixation through the intermuscular space approach (OLIF combined group). In addition, 137/144 cases in the combined group were primarily treated by posterior pedicle screw fixation, while the treatments were postponed in 7 cases. There were 190 cases of single fusion segments, 11 of 2 segments, 21 of 3 segments, and 13 of 4 segments. Intraoperative and postoperative complications were observed.

RESULTS

Average follow-up time was 15.6 ± 7.5 months (ranged from 6 to 36 months). Five cases were lost to follow-up (2 cases from the OLIF alone group and 3 cases from the OLIF combined group). There were 7 cases of vascular injury, 22 cases of endplate damage, 2 cases of vertebral body fracture, 11 cases of nerve injury, 18 cases of cage sedimentation or cage transverse shifting, 3 cases of iliac crest pain, 1 case of right psoas major hematoma, 2 cases of incomplete ileus, 1 case of acute heart failure, 1 case of cerebral infarction, 3 case of left lower abdominal pain, 9 cases of transient psoas weakness, 3 cases of transient quadriceps weakness, and 8 cases of reoperation. The complication incidence was 32.34%. Thirty-three cases occurred in the OLIF alone group, with a rate of 36.26%, and 43 cases in the group of OLIF combined posterior pedicle screw fixation, with a rate of 29.86%. Fifty-seven cases occurred in single-segment fusion, with a rate of 30.0% (57/190), 4 cases occurred in two-segment fusion, with a rate of 36.36% (4/11), 9 cases occurred in three-segment fusion, with a rate of 42.86% (9/21), and 6 cases occurred in four-segment fusion, with a rate of 46.15% (6/13).

CONCLUSION

In summary, OLIF is a relatively safe and very effective technique for minimally invasive lumbar fusion. Nonetheless, it should be noted that OLIF carries the risk of complications, especially in the early stage of development.