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Background The anterior cage at L5-S1 segment is more vulnerable to anterior migration because of the sacral slope, the greater disc angle (DA), the higher shear force, and the weaker pedicle screw fixation at S1. We hypothesized that a supplemental screw (SS) fixation is effective for the prevention of anterior cage migration in oblique lateral interbody fusion (OLIF) at L5-S1. Methods This study involved 61 consecutive patients who underwent OLIF at L5-S1 and had more than 1-year regular follow-up. In the first 35 cases, the anterior cage was fixed with pedicle screws only (non-SS group). In the remaining 26 cases, the anterior cage was fixed with a SS and pedicle screws (SS group). Radiological parameters including anterior disc height (ADH), posterior disc height (PDH), DA, cage migration, cage subsidence, and fusion rate at L5-S1 were compared between the two groups. Result Of the total 61 patients, fifteen (24.6%) patients had an anterior cage migration of >2 mm and six (9.8%) patients had an anterior cage migration of >5 mm. Baseline demographic characteristics were similar between the two groups. The mean cage migration was 2.0 ± 3.1 mm in the non-SS group and 0.9 ± 0.9 mm in the SS group (P = 0.038). Thirteen (37.1%) patients had a cage migration of >2 mm in the non-SS group, while only two (7.7%) had a cage migration of >2 mm in the SS group (P = 0.002). There were no significant differences in the ADH, PDH, DA, cage subsidence, and fusion rate between the two groups (all P > 0.05). There was no SS-related complication in the SS group. Conclusions SS fixation in front of the anterior L5-S1 cage is simple, safe, and effective for the prevention of anterior cage migration in OLIF at L5-S1.

Retrospective radiological analysis.To demonstrate the radiological outcome after a modified anterior column realignment (mACR) with partial anterior longitudinal ligament (ALL) release in oblique lateral interbody fusion (OLIF).Anterior column realignment (ACR) remains a powerful sagittal correction technique in minimally invasive adult spinal deformity surgery and is often combined with posterior column osteotomy (PCO) to achieve more lordosis. OLIF is ideal for ACR because the anterior-to-psoas corridor typically involves the anterolateral half of the disk.This study included 112 operated disk levels of 101 consecutive patients who underwent OLIF between L2-L3 and L4-L5 using a 12° lateral cage. The mACR was performed at 73 (65.2%) levels with 30% to 50% sectioning of the ALL. Each operated level was grouped according to the mACR and additional PCO as: (1) no mACR, OLIF only (n=39); (2) mACR with no PCO (n=18); (3) mACR with grade 1 PCO (n=27); (4) mACR with grade 2 PCO (n=22); or (5) mACR with grade 3 PCO (n=6).At the last follow-up, the mean disk lordotic angles were 10.9±2.9°, 12.6±3.0°, 13.3±3.9°, 16.7±3.2°, and 16.8±2.4° in the no mACR, mACR with no PCO, mACR with grade 1 PCO, mACR with grade 2 PCO, and mACR with grade 3 PCO groups, respectively ( P0.001). The mean increases in disk lordotic angle were 5.8±4.1°, 12.1±6.1°, 13.5±8.7°, 15.8±6.7°, and 17.9±6.2° in each group, respectively ( P0.001).ACR can be performed with partial ALL release under direct vision in OLIF without deep dissection into the ventral disk space. The mACR in OLIF is a simple, safe, and effective technique for anterior column lengthening.4.

BACKGROUND Mixed reality (MR) is a hybrid system that projects virtual elements into reality. MR technology has the advantage of providing immersive learning using various real-world tools. However, studies on educational programs using MR are scarce. OBJECTIVE This study aimed to investigate the educational effects of and satisfaction with an MR-based trauma decision-making simulator. METHODS A total 40 of trainees self-selected to participate in this experiment. All participants participated in the MR trauma simulator for approximately 30 minutes and conducted voluntary learning without any external help. Declarative knowledge, measured using 20 multiple-choice questions, was assessed before and after MR trauma training. To confirm the educational effect, test scores before and after MR trauma training were compared using a paired t-test. Student satisfaction after training was measured using a ten-item questionnaire rated on a five-point Likert scale. RESULTS A pretest-posttest comparison yielded a significant increase in declarative knowledge. The percentage of correct answers to multiple choice questions increased (from a mean of 42.3, SD 12.4 to 54.8, SD 13) after the MR-based trauma assessment and treatment training (P < 0.001). Of the participants, 79.45% were satisfied with the overall experience of using the MR simulator. CONCLUSIONS This study demonstrated a meaningful educational effect of the MR-based trauma training system even after a short training time.

Optimal restoration of the L5-S1 disc angle (DA) is an important surgical goal in spinal reconstructive surgery. Anterior approach is beneficial for L5-S1 DA reconstruction and fusion. However, factors associated with a greater DA restoration in oblique lateral interbody fusion (OLIF) at L5-S1 have not been studied.This study aimed to identify factors that aid in achieving a greater DA in OLIF at L5-S1.A retrospective analysis.This study involved 61 consecutive patients who underwent OLIF at L5-S1 for lumbar degenerative disease and were followed for more than 1 year. Patients with incomplete data or posterior column osteotomy at L5-S1 were excluded.The L5-S1 DA was measured preoperatively, postoperatively, and at the last follow-up on standing lateral lumbar radiographs. The associations between demographics and/or surgical and/or radiological factors and the L5-S1 DA at the last follow-up were analyzed using multiple regression analysis.Demographics and surgical factors were reviewed from the medical records with respect to age, sex, body mass index, bone mineral density, diagnosis, surgery level, cage parameters (cage lordotic angle and height), laminectomy performed and/or not performed, estimated blood loss, operative time, configuration of the left common iliac vein. Radiological factors were measured with respect to sagittal parameters, the L5-S1 disc parameters, and the postoperative cage parameters.The mean preoperative DA at L5-S1 was 5.4±5.0°, which increased to 18.9±5.6° postoperatively (p.001) and was maintained as 16.5±5.9° at the last follow-up (p.001). The preoperative DA, end plate lesions, anterior spur, facet joint osteoarthritis, or cage position at L5-S1 did not affect the DA at the last follow-up (all p.05). Multiple regression analysis showed four independent variables, including increased age, increased cage lordotic angle, laminectomy performed, and absence of cage subsidence as the factors associated with the greater DA at L5-S1.OLIF at L5-S1 showed favorable DA restoration regardless of the preoperative conditions. To achieve a greater DA, surgeons should try to distract the anterior disc space for insertion of a larger lordotic cage. Laminectomy during posterior fixation is recommended for achieving additional DA restoration.

Compared with posterior interbody fusion techniques, oblique lateral interbody fusion (OLIF) offers a larger fusion bed with greater intervertebral space access, use of larger cages, more sufficient discectomy, and better end-plate preparation. However, the fusion rate of OLIF is similar to that of other interbody fusions. This study aimed to examine the factors associated with nonunion in OLIF.This study examined 201 disc levels from 124 consecutive patients who underwent OLIF for lumbar degenerative diseases with 1-year regular follow-up. Demographic and surgical factors were reviewed from the medical records. Radiological factors measured were sagittal parameters, intervertebral disc angle (DA) before surgery and at the final follow-up, presence of vertebral end-plate lesions, and cage subsidence. Multivariable logistic regression analysis was performed to identify the factors associated with nonunion.Among the 201 discs, 185 (92.0%) achieved union at 1-year followed up. Smoking, surgery at the L5-S1 level, not performing laminectomy, and a large intervertebral DA were factors associated with nonunion in OLIF (all P 0.05). Multivariable logistic regression analysis showed two independent variables (surgery at L5-S1 level and not performing laminectomy) as risk factors for nonunion in OLIF.Not performing laminectomy and surgery at the L5-S1 level were risk factors for nonunion in OLIF. To reduce the nonunion rate, surgeons should consider additional stabilization strategies for the L5-S1 OLIF and perform laminectomy.

Background Oblique lateral interbody fusion (OLIF) at lumbosacral junction is typically performed on the central window between the bifurcations of iliac vessels. However, the central window of lumbosacral transitional vertebrae (LSTVs) is usually obstructed by the iliocaval venous structures. We aimed to describe the vascular anatomy and surgical approach in OLIF at LSTVs compared with those in OLIF at typical L5-S1 junction. Methods Sixty-eight consecutive patients who underwent OLIF at lumbosacral junction were included. Of these, 31 patients had LSTVs and 37 patients had typical L5-S1 junction. The position of the iliocaval junction and the configuration of the left common iliac vein were compared using the preoperative CT and MR images of the lumbar spine. The surgical approach and intraoperative vascular findings were analyzed. Results Almost 70% of LSTVs had the iliocaval junction at low or very low position. Mobilization of left common iliac vein for central window was potentially difficult in almost 74% of OLIF at LSTVs while it was not required or was potentially easy in almost 80% of OLIF at typical L5-S1. Vascular injury was identified in 2 (6.5%) patients with OLIF at LSTVs and in 3 (8.1%) patients with OLIF at typical L5-S1 junction (P = 0.904). Conclusions In our series, OLIF at LSTVs was performed through lateral window in 93.5% of the cases. Preoperative evaluation of the iliocaval junction using CT/MR of lumbar spine was reliable and valid in the determination of OLIF approach at lumbosacral junction.

This study investigated relationships of Oswestry Disability Index (ODI) and Short Form 36 (SF-36) total and subscale scores with global spinal parameters in patients with degenerative lumbar scoliosis (DLS). This was a prospective single-center study of 126 consecutive patients with DLS. Disability was evaluated using the ODI and SF-36 total and subscale scores. Sagittal and coronal parameters were measured. Pearson’s correlation analysis was performed to determine relationships between disability and radiographic parameters. The study population included 76 women and 15 men (mean age, 70.2 ± 8.4 years). Mean Cobb angle was 18.9° ± 8.0°. The ODI total score and SF-36 physical component score were only correlated with coronal parameters. ODI pain intensity, personal care, lifting, sitting, and sex life domains were only correlated with coronal parameters. The walking, standing, social life, and traveling domain scores were correlated with coronal and sagittal parameters. The SF-36 bodily pain and vitality domain scores were only correlated with coronal parameters. The SF-36 physical function domain score was correlated with both coronal and sagittal parameters. Among the clinical and radiographic parameters, the personal care score and the coronal vertical-axis had the strongest correlation (r = 0.425), although the r2 value was only 0.18. ODI total score and most of the subscale scores were significantly, but weakly correlated with coronal parameters. Sagittal parameters were only correlated with some of the ODI and SF-36 subscale scores. Analysis using ODI and SF-36 subscale scores may aid in understanding and treatment of disability in patients with DLS.

This study evaluated the diagnostic performance of the proton density fat fraction (PDFF) in predicting the progression of osteoporotic vertebral compression fractures (OVCFs). The cohort in this retrospective study consisted of 48 patients with OVCFs who underwent spine MRI that included PDFF between December 2016 and June 2018. The patients were divided into two groups (with versus without OVCF progression, based on the radiographic results obtained at the 6-month follow-up examination). Two musculoskeletal radiologists independently calculated the PDFF of the fracture and the PDFF ratio (fracture PDFF/normal vertebrae PDFF) using regions of interest. The mean values of these parameters were compared between the two groups, and the receiver operating characteristic curves were analysed. The mean age was significantly higher in the group with OVCF progression (71.6 ± 8.4 years) than in the group without (64.8 ± 10.5 years) (p = 0.018). According to reader 1, the PDFF ratio was significantly lower in the group with OVCF progression versus that without OVCF progression (0.38 ± 0.13 vs 0.51 ± 0.20; p = 0.009), whereas the difference in the PDFF itself was not statistically significant. The PDFF ratio [area under the curve (AUC) = 0.723; 95% confidence interval (CI), 0.575–0.842] had a larger AUC than did the PDFF (AUC = 0.667; 95% CI, 0.516–0.796). The optimal cut-off value of the PDFF ratio for predicting OVCF progression was 0.42; this threshold corresponded to sensitivity, specificity, and accuracy values of 84.0%, 60.9%, and 72.9%, respectively. The age and PDFF ratio can be used to predict OVCF progression. • Chemical shift-encoded magnetic resonance imaging provides quantitative parameters for predicting OVCF progression. • The PDFF ratio is significantly lower in patients with OVCF progression. • The PDFF ratio is superior to the PDFF for predicting OVCF progression.

Background Managing unilateral vertically displaced sacral fractures remains a challenge. A triangular osteosynthesis (TOS), which involves fixing the fractured sacrum using unilateral spinopelvic fixation and a supplemental ilio-sacral screw, continues to gain popularity as it facilitates early mobilization and improves the long-term outcome. However, it has limitations, such as destruction of the L5-S1 joint, the need for additional removal surgery, and an increased risk of infection due to the large incision. An S1 pediculoiliac construct was proposed to overcome this limitations. Its use also has complications, however, including a painful hardware prominence due to the traditional iliac screw, excessive soft tissue retraction, and limited reduction capability. Case Description A 20-year-old woman fell from a height of 6 meters and sustained a vertical shear type sacral fracture on the left side with substantial vertical displacement. We reduced and fixed the fracture using a TOS using an S1 pedicle screw and an S2 alar iliac screw (S2AIS). The patient was allowed immediate weight-bearing as tolerated. We achieved good reduction and union with a small vertical incision, without the destruction of L5-S1 joints, a symptomatic implant prominence, or wound complications. Conclusions For unilateral vertically unstable sacral fractures, TOS using S1 pedicle screws and S2AIS is safe and has the advantage such as maintaining mobility in the lumbar pelvic region, small size wounds, and reduced soft tissue damage, and it may have a potentially low infection rate. Further studies are needed to determine the specific indications and validate the effectiveness of this procedure.

Study Design: Retrospective case-control study. Objectives: Vertebral end plate (EP) lesions include Modic changes, Schmorl’s nodes, EP erosion, EP sclerosis, and so on. While previous studies have mostly focused on the association between vertebral EP lesions and low back pain, few studies evaluated the influence of vertebral EP lesions on the radiological outcomes in lumbar interbody fusion. Methods: This study included a total of 125 operated disc levels from 86 consecutive patients who underwent a 1- or 2-level oblique lateral interbody fusion (OLIF) and had more than 1-year regular follow-up. The presence of vertebral EP lesions, changes in disc heights/angle, cage subsidence, and fusion grade were examined. The associations between vertebral EP lesions and radiological parameters were analyzed. Result: The presence of Modic changes, Schmorl’s node, EP cartilage erosion, and EP sclerosis were found in 72 (57.6%), 26 (20.8%), 31 (24.8%), and 44 (35.2%) disc levels, respectively. The mean anterior disc height increased from 6.9 ± 3.8 mm to 13.1 ± 2.7 mm ( P < .001) and the mean segmental angle increased from 2.9° ± 5.8° to 9.2° ± 4.8° ( P < .001) at the last follow-up. The overall fusion rate was 98.4% (123/125) and cage subsidence rate was 7.2% (9/125). All radiological parameters and cage subsidence rate were not different regardless of vertebral EP lesions. Conclusions: Vertebral EP lesions did not affect the overall radiological outcome in 1- or 2-level OLIF. These results come from the stable contact between lateral cage and peripheral rim of vertebral EP.

STUDY DESIGN Retrospective study. OBJECTIVE We identified radiological risk factors for neurological deficits in mid and low lumbar spinal fractures. SUMMARY OF BACKGROUND DATA Although numerous studies have focused on radiological risk factors for neurological deficits in spinal cord injury or thoracolumbar junction area fractures, few have examined mid and low lumbar fractures at the cauda equina level. METHODS We retrospectively reviewed 71 consecutive patients who suffered acute traumatic mid and low lumbar fractures (L2-L5) corresponding to the cauda equina level, as confirmed on magnetic resonance imaging. We defined a neurological deficit as present if the patient had any sensory or motor deficit in the lower extremity or autonomic system at the initial assessment. Various computed tomography parameters of canal stenosis, vertebral body compression, sagittal alignment, interpedicular distance, and presence of vertical laminar fractures were analyzed as independent risk factors to predict neurological deficits using multivariate logistic regression analyses. RESULTS At the initial assessment, 31 patients had neurological deficits. Fracture level, AO fracture type, canal encroachment ratio, vertebral compression ratio, interpedicular distance ratio, and presence of a vertical laminar fracture were significantly associated with the presence of neurological deficits (all P

A cross-sectional radiological study. We aimed to examine the degenerative changes of sagittal alignment in patients with Roussouly type 1. Roussouly type 1 is unique in shape, characterized by short lumbar lordosis (LL) with the apex at L5 and thoracolumbar kyphosis (TLK). Because of the unique shape of sagittal alignment and the small pelvic incidence (PI) in Roussouly type 1, the degenerative changes of sagittal alignment may differ. A total of 145 patients with Roussouly type 1 were recruited and distributed into three age groups; Group I (N = 40) were young patients (20–40 years of age), Group II (N = 47) were middle-aged patients (45–60 years of age), and Group III (N = 48) were elderly patients (>65 years of age). Sagittal parameters including sagittal vertical axis (SVA), PI, pelvic tilt (PT), L1S1 LL, L4S1 LL, thoracic kyphosis (TK), and TLK were measured using Surgimap® software. The occurrence of lumbar retrolisthesis was also examined. The SVA, PI, PT, L1S1 LL, L4S1 LL, TK, and TLK in group I were − 25.9° ± 23.4 mm, 37.1° ± 5.3°, 10.3° ± 5.5°, 42.7° ± 8.8°, 35.5° ± 6.9°, 29.5° ± 23.5°, and 9.7° ± 5.9°, respectively. Among the Groups I, II, and III, there was a stepwise increase in the SVA, PT, TLK, and lumbar retrolisthesis (all P

Study Design: Retrospective case-control study. Objectives: To investigate whether mechanical bowel preparation (MBP) improve surgical performance and decrease operative complications in anterior lumbar interbody fusion (ALIF). Methods: This study involved a retrospective analysis of 48 consecutive patients who underwent ALIF with MBP and a control cohort of 50 consecutive patients who underwent the same surgeries without MBP. The quality of each surgical procedure, operative time, estimated blood loss (EBL), intraoperative complications, changes in vital signs and patient symptoms on the day of surgery, and bowel function postoperatively were also compared between the procedures. Results: Baseline demographic characteristics were similar between the 2 groups (all Ps > .05). The quality of each procedure, operative time, EBL, intraoperative complications, and changes in body temperature and heart rate were not different between the groups (all Ps > .05). The MBP group showed more headache, tiredness, thirst, and abdominal discomfort (all Ps < .001) and decrease of the systolic blood pressure ( P = .041) on the day of surgery. The return of bowel movement was not different between the groups ( P = .278). Conclusions: Given the similar surgical result with the substantial patient discomfort, MBP can be omitted in ALIF.

The EOS is a medical imaging system that incorporates simultaneous orthogonal images, producing three-dimensional (3D) reconstructions of the whole skeletal system in various functional positions. Despite growing interest in the pelvic 3D position, the validity of the EOS has not yet been well studied. We investigated the trueness and precision of EOS imaging for pelvic parameters and orientation and assessed whether the measurement using the EOS was affected by the pelvic orientation itself. The orientation of the anterior pelvic plane and pelvic parameters of a custom-made pelvic phantom were measured by three raters using the EOS, and the measurements obtained were compared with the true values. The standard deviations of the measurement errors were 3.23°, 0.26°, 0.23°, 2.98°, 0.88°, and 3.22° for flexion, obliquity, rotation, pelvic incidence, spinopelvic tilt, and sacral slope, respectively. The root-mean square averages of the standard deviation of each measurement were 4.05°, 0.41°, 0.28°, 4.80°, 0.99°, and 5.13°, respectively. The measurement errors for sacral slope correlated significantly with geometric means of flexion, obliquity, and rotation (r = 0.364, p = 2.67 × 10–11). The EOS rendered accurate and reliable measurements regarding pelvic 3D position, even with positional variation, but positional variation could affect measurements of sacral slope.

Study Design: Retrospective case series Objectives: Reduction of translational/angular slip is a favorable radiological result in spinal fusion for degenerative spondylolisthesis, although its clinical significance remains controversial. Few studies have investigated slip reduction and associated factors in oblique lumbar interbody fusion (OLIF) for degenerative spondylolisthesis. Methods: This study involved a retrospective analysis of 56 operated levels of 52 consecutive patients who underwent OLIF for degenerative spondylolisthesis and had more than 1-year of regular follow-up. Translational/angular slip, anterior/posterior disc height, and spinopelvic parameters were measured preoperatively, postoperatively at 6-weeks, and at the last follow-up. Demographic, radiological, and surgical parameters were analyzed to determine factors associated with the amount of slip reduction. Result: The mean follow-up duration was 30.4 ± 12.9 months (range, 12 to 61). The mean decrease in translational slip was 5.7 ± 2.1 mm (13.6 ± 5.5%) and the mean increase in angular slip was 7.9 ± 7.1° at the last follow-up (both P < 0.001). The amount of slip reduction was greater in female sex, age < 65 years, use of a 12° cage, cage position from the anterior disc margin of < 7 mm, and cases with posterior decompression (laminectomy with inferior facetectomy). Conclusions: OLIF showed satisfactory translational/angular slip reduction in degenerative spondylolisthesis. Surgical techniques for optimal reduction include the use of a large angle cage, anterior cage placement, and resection of the inferior facet.

OBJECTIVE. The purpose of this study was to evaluate the added value of proton density fat fraction (PDFF) in differentiating vertebral metastases from focal hematopoietic marrow depositions. MATER...

STUDY DESIGN This was a retrospective study. OBJECTIVE The objective of this study was to evaluate whether the anatomy of the left common iliac vein (LCIV) affects the radiologic outcomes in oblique lateral interbody fusion (OLIF) at L5-S1. SUMMARY OF BACKGROUND DATA Upward mobilization and retraction of the LCIV is an essential technique in OLIF at L5-S1. However, mobilization of the LCIV is sometimes difficult and may affect the surgical outcomes in OLIF at L5-S1. METHODS This study involved 52 consecutive patients who underwent OLIF at L5-S1 and had >1-year regular follow-up. The configuration of LCIV on preoperative axial magnetic resonance images of the lumbar spine was categorized into 3 types according to the difficulty of mobilization: type I (no requirement for mobilization), type II (potentially easy mobilization), and type III (potentially difficult mobilization). Radiologic parameters included anterior/posterior disk heights (ADH/PDH), disk angle (DA), cage migration, cage subsidence, cage position, and fusion rate at L5-S1. Intraoperative/perioperative events associated with OLIF at L5-S1 were reviewed. Radiologic outcomes among the LCIV types were compared. RESULTS There were 19 men and 33 women with a mean age of 62.8±9.7 years. The mean follow-up duration was 24.8±15.5 months. The LCIV anatomy was type I in 25 (48.1%) patients, type II in 14 (26.9%), and type III in 13 (25.0%). The mean ADH increased from 7.0±4.7 to 16.9±4.1 mm at the last follow-up (P

Links between sagittal spinal alignment and acetabular orientation attract considerable research attention with the goal of understanding “hip-spine syndrome.” However, whether pelvic incidence (PI) is related to acetabular orientation remains debatable. The purpose of the present study was to determine 1. whether the correlation between PI and acetabular orientation is present in pelvises of young healthy adults, and 2. whether the correlation is present in subgroups of sex, or between the left and right pelvis. We analyzed 100 abdominopelvic computed tomography (CT) scans of skeletally healthy young adults. We measured PI and acetabular orientation with three-dimensional (3D) measurements. The orientation of 200 acetabula was measured using 3D reconstructed models of 100 pelvises in the coordinate system based on the anterior pelvic plane (APP). To quantify the acetabular orientation, the radiographic definitions of anteversion and inclination were used. To examine the correlation between acetabular orientation and PI, Pearson's correlation was used. The mean PI was 46.9° ± 10.2°, and the mean acetabular orientation 15.3° ± 5.7° anteverted and 37.5° ± 3.9° inclined. While no significant difference in the PI was observed, the average acetabular orientation of female pelvises (anteversion, 17.5° ± 5.6°; inclination, 36.7° ± 3.7°) was more anteverted and less inclined compared to that of male pelvises (anteversion, 13.2° ± 4.9°; inclination, 38.3° ± 3.9°, respectively; P values < .05). The correlation between PI and acetabular orientation was statistically not significant. After division of study group by sex, the linear correlation between PI and acetabular orientation was not statistically supported. The asymmetry of the acetabular orientation between the left and right sides was not significant. The linear relationship between anatomical acetabular orientation and PI was not evident in the normal population. Our finding thus proves the absence of a linear relationship between the upper and lower articular orientation of the pelvic segment and deepens the understanding of the characteristics of acetabular orientation and PI.

A cross-sectional radiological study.We aimed to examine the degenerative changes of sagittal alignment in patients with Roussouly type 1. Roussouly type 1 is unique in shape, characterized by short lumbar lordosis (LL) with the apex at L5 and thoracolumbar kyphosis (TLK). Because of the unique shape of sagittal alignment and the small pelvic incidence (PI) in Roussouly type 1, the degenerative changes of sagittal alignment may differ.A total of 145 patients with Roussouly type 1 were recruited and distributed into three age groups; Group I (N = 40) were young patients (20-40 years of age), Group II (N = 47) were middle-aged patients (45-60 years of age), and Group III (N = 48) were elderly patients (65 years of age). Sagittal parameters including sagittal vertical axis (SVA), PI, pelvic tilt (PT), L1S1 LL, L4S1 LL, thoracic kyphosis (TK), and TLK were measured using SurgimapThe SVA, PI, PT, L1S1 LL, L4S1 LL, TK, and TLK in group I were - 25.9° ± 23.4 mm, 37.1° ± 5.3°, 10.3° ± 5.5°, 42.7° ± 8.8°, 35.5° ± 6.9°, 29.5° ± 23.5°, and 9.7° ± 5.9°, respectively. Among the Groups I, II, and III, there was a stepwise increase in the SVA, PT, TLK, and lumbar retrolisthesis (all P 0.001). The PI, L4S1 LL, and TK were identical among the three groups.Degenerative changes of Roussouly type 1 include increase in the SVA, PT, TLK, and lumbar retrolisthesis, while the PI, L4S1 LL, and TK remain unchanged.Level IV.

In oblique lateral interbody fusion (OLIF), the lateral cage enters into the disc space obliquely, and is then turned to the true lateral direction to achieve a lateral lumbar interbody fusion. The OLIF cage is sometimes placed asymmetrically although it seemed to be placed accurately on intraoperative C-arm images. The present study aimed to investigate the accuracy of cage placement and its effect on the radiological outcome in OLIF.This study involved a retrospective radiological analysis of 127 lateral cages in 75 consecutive OLIF patients. The cage deviations from the midline and cage obliquity were evaluated using three sets of images: (1) intraoperative C-arm fluoroscopy, (2) postoperative standing radiographs, and (3) postoperative computed tomography (CT).The mean cage deviation from the midline was measured as 2.5 ± 2.7 mm on intraoperative C-arm images, but was found to be more deviated on postoperative radiographs and CT (5.4 ± 3.8 mm and 3.8 ± 3.7 mm; P = 0.000 and 0.005, respectively). The cage obliquity on the intraoperative lateral C-arm was minimal in 26 (20.5%) cases, mild in 69 (54.3%), and moderate in 32 (25.2%), but was found to be more obliquely on postoperative radiographs as minimal in 9 (7.1%), mild in 55 (43.3%), and moderate in 63 (49.6%) (P 0.001). Anterior/posterior disc heights, disc lordotic angle, fusion rate, and cage subsidence rate were not different according to cage obliquity (all P 0.05).Cage deviation from the midline and obliquity is underestimated on intraoperative C-arm images in OLIF. Although minimal cage deviation and obliquity did not affect the radiological outcome, great care should be made for the orthogonal cage insertion.

Study design Technical report. Objective To demonstrate the use of an alternative surgical corridor in oblique lateral interbody fusion (OLIF) at the L5-S1 segment. Summary of background data OLIF L5-S1 is essentially performed through the central disk space between the bifurcations of the iliac vessels, which is sometimes difficult due to the vascular structures that obstruct the surgical field. Another concern is retrograde ejaculation following superior hypogastric plexus injury in male patients. Materials and methods The alternative surgical corridor involves the lateral disk space external to the left iliac vessels. The patient position and the retroperitoneal approach are similar to those used in the conventional OLIF L5-S1. The left iliac vessels are identified and mobilized medially to the midline of the L5-S1 disk space. The vascular structures are then protected using the conventional OLIF 51 retractor system. Results Six patients underwent OLIF L5-S1 through the alternative lateral surgical corridor. The L5-S1 disk spaces were always exposed sufficiently for disk preparation and cage insertion. The postoperative radiographs showed a satisfactory L5-S1 reconstruction with good cage position. There were no perioperative complications during the surgical access and reconstruction procedures. Conclusions When the central approach to the L5-S1 disk space poses a risk of vascular or superior hypogastric plexus injury, use of a lateral approach external to the left iliac vessels can be an alternative method to perform OLIF L5-S1.

This was a radiologic validity and reliability study.We aimed to assess the validity and reliability of measurements from standing lateral cervical radiography (XR), reconstructed midsagittal images of supine cervical computerized tomography (CT) scans, and supine magnetic resonance imaging (MRI) for evaluating C2-C7 distance (C27 SVA), C2-C7 Cobb angle (CL), T1 slope (T1S), thoracic inlet angle (TIA), and neck tilt (NT).XR is the criterion standard imaging modality for measuring cervical sagittal alignment parameters. However, overlapping bony structures and soft tissue often make the upper end of the manubrium and cervicothoracic junction indiscernible. CT and MRI can overcome this limitation, but their reliability and validity have not been fully elucidated.Fifty sets of three examinations from our database have been randomly selected. Three experienced spinal surgeons independently measured C27 SVA, CL, T1S, TIA, and NT. Paired t test and Pearson correlation were used to analyze the validity of CT and MRI in comparison with that of XR. Interobserver and intraobserver reliability were assessed by using the intraclass correlation coefficient (ICC).The paired t test confirmed the similarities of all CT (except C27 SVA) and MR parameters (except C27 SVA and CL) to the XR parameters (all P0.05). All parameters except C27 SVA were correlated (Pearson correlation coefficient, 0.523-0.913). Correlation was highest between CT and MRI and lowest between CT and XR. All three imaging modalities had excellent intraobserver and interobserver reliability (ICC range: 0.770-0.999). Intraobserver and interobserver reliability were highest with MRI and lowest with XR.CT and especially MRI were more reliable than XR for evaluating cervical sagittal alignment parameters. Considering the reliability and radiation exposure, MRI is a good alternative to XR for measuring cervical sagittal alignment parameters, especially thoracic inlet alignment.4.

Although oblique lateral interbody fusion (OLIF) utilizes the similar approach in anterior lumbar interbody fusion (ALIF), OLIF is essentially a lateral lumbar interbody fusion (LLIF). Therefore, OLIF may have advantages in LLIF that the lateral cage can achieve greater restoration of the disc height and angle. We aimed to compared the surgical outcomes between OLIF and ALIF.This study involved 47 consecutive patients who underwent a single-level OLIF and 45 consecutive patients who underwent a single-level ALIF at L2-L5 levels. Radiological measurements included the changes of anterior/posterior disc height, coronal/sagittal disc angle, foramen cross-sectional area (CSA), cage position from the anterior margin of the lower vertebra, fusion rate, and cage subsidence using the serial radiographs and computed tomography preoperatively and at the postoperative 1-year follow-up. Clinical outcomes were assessed by visual analog scale (VAS) for back/leg pain, Oswestry disability index (ODI), and the occurrence of perioperative complications.The baseline radiological and clinical parameters were similar between the OLIF and ALIF groups (all P 0.05). At postoperative 1 year, the mean anterior disc height was higher in the OLIF group than the ALIF group (11.4 ± 1.9 mm vs. 9.6 ± 2.6 mm, P = 0.021). The mean sagittal disc angle was also greater in the OLIF group than the ALIF group (10.9 ± 4.4° vs. 8.9 ± 5.8°, P 0.001). The mean cage position was 5.8 ± 2.1 mm in the OLIF group and 8.7 ± 2.3 mm in the ALIF group (P 0.001). There was no difference in the postoperative changes of coronal disc angles, foramen CSA, fusion rate, cage subsidence, VAS for back/leg pain, ODI, and the occurrence of perioperative complications between the OLIF and ALIF groups (all P 0.05).OLIF showed a greater increase in disc height and segmental lordosis than ALIF with comparable complications. OLIF is a meaningful progress from ALIF.

Objectives To examine how spinopelvic morphology changes after traumatic spinopelvic dissociation and whether these changes affect the sagittal balance of the spine. Design Retrospective analysis. Setting Level I trauma center. Patients Thirty-nine consecutive patients who were diagnosed with traumatic spinopelvic dissociation and had a minimum 2-year radiological follow-up were included. Intervention Nineteen patients underwent spinopelvic pedicle screw fixation, 11 patients underwent percutaneous iliosacral screw fixation, and 9 patients were treated conservatively. Main outcome measurements The main outcome measurements are as follows: (1) injury morphology (injury type and kyphotic angulation) at the initial and follow-up visits; (2) sagittal vertical axis (SVA) at the 2-year follow-up; (3) spinopelvic parameters [pelvic incidence (PI), sacral slope, pelvic tilt, lumbar lordosis, and thoracic kyphosis] at the 2-year follow-up; and (4) bodily pain and Oswestry Disability Index at the 2-year follow-up. Results There were 21 men and 18 women, with a mean age of 28.3 years (15-62 years). At the 2-year follow-up, the mean SVA was 5.4 ± 4.1 cm and the mean PI was 76.9 ± 24.6 degrees. Factors related to SVA after traumatic spinopelvic dissociation were PI (r = 0.441, P = 0.017), pelvic tilt (r = 0.387, P = 0.038), and injury type of complete displacement (r = 0.372, P = 0.047). The bodily pain and Oswestry Disability Index was significantly poorer in patients with SVA modifier "+" than in patients with SVA modifier "0." Conclusions Lumbosacral kyphosis after traumatic spinopelvic dissociation increases PI, which can affect the sagittal balance of the spine and clinical outcome. Restoration of lumbosacral orientation is important for preventing sagittal imbalance. Level of evidence Prognostic Level IV. See Instructions for Authors for a complete description of levels of evidence.

STUDY DESIGN This was a radiographic validity and reliability study. OBJECTIVE We assessed the validity and reliability of measurements made on standing lateral lumbar radiographs, compared with lateral whole-spine radiographs, for evaluating spinopelvic parameters and lumbar lordosis (LL). SUMMARY OF BACKGROUND DATA A lateral whole-spine radiograph is the gold standard image for measurement of spinopelvic parameters. However, little evidence is available on the reliability of measurements made on such radiograph. A standing lateral lumbar radiograph is routinely obtained from patients with back pain and/or a disability. This image can include upper end plate of L1 vertebra, sacral dome and both femoral heads. Thus, this radiograph can be used for evaluation of spinopelvic parameters. MATERIALS AND METHODS We randomly selected 50 sets of digital radiographs (standing lateral lumbar and lateral whole-spine radiographs) from our database. Three experienced spinal surgeons independently measured LL, pelvic incidence, pelvic tilt, and sacral slope on all images. A paired t test and Pearson correlation was used to analyze the validity of the lateral lumbar radiograph. Interobserver and intraobserver reliabilities were assessed by intraclass correlation coefficient. RESULTS Thee spinopelvic parameters and LL measured on lateral lumbar radiographs were similar to those measured on lateral whole-spine radiographs (All P-values >0.05, Pearson correlation coefficients, 0.807-0.969). The intraobserver and interobserver reproducibilities of both measurement types were good-to-excellent. CONCLUSIONS Spinopelvic parameters and LL values measured on lateral lumbar radiographs were reproducibly similar to those measured on lateral whole-spine radiographs. Use of a standing lateral lumbar radiograph is reasonable when spinopelvic parameters and LL are to be measured.

A radiological study. To examine lumbar segment angle according to the Roussouly type of global sagittal alignment and to determine the reference disc angles in minimally invasive surgery (MIS) for adult spinal deformity. Optimal restoration of lumbar lordosis (LL) in adult spinal deformity surgery includes achieving the ideal shape of LL as well as the amount of LL. However, the distribution of lumbar segment angles by the Roussouly type has yet to be elucidated. Forty sets of whole spine lateral radiographs covering the four Roussouly types (N = 160) were obtained from a database of asymptomatic adult subjects. Global and spinopelvic parameters were measured. Disc and vertebral angles at each lumbar level were compared among the Roussouly types. There were 75 (46.9%) men with a mean age of 32.8 ± 8.9 years among the total of 160 study subjects. A significant difference was found in spino-sacral angle, sacral slope, pelvic incidence, LL, and lower arc of LL (L4S1) among the Roussouly types (all P

Bleeding and hematoma formation is rarely reported in percutaneous vertebroplasty procedure. An 84 year old male presented with a large paraspinal muscle hematoma after a percutaneous vertebroplasty. The patient had neither any prior bleeding disorder nor any anticoagulant treatment. Vital signs of the patient were unstable, and his hemoglobin level decreased daily. After a month of conservative treatment, including transfusion, cryotherapy, pain control and bed rest, his hemoglobin level remained stable and he showed relief from pain. Four months later, hematoma resolved spontaneously and he could walk without back pain.

This case report describes a case of an elderly woman diagnosed with acute osteoporotic vertebral compression fracture (OVCF) at thoracic spine after using an electrical automated massage chair (EAMC). Care should be taken when using an EAMC, especially by those with or at risk of developing osteoporosis. Osteoporotic vertebral compression fracture (OVCF) is a common problem among elderly population and presents a high burden to society. Osteoporotic fractures may occur after a minimal trauma of the vertebrae. Electrical automated massage chair (EAMC) is a device that uses a programmed algorithm to perform automated massage. The massage chair, a popular device among elderly with back pain, relies on friction and rhythmic tapping created by a motorized roller. However, research regarding the safety of this device is lacking, especially in the perspective of OVCF. We present a case of an elderly woman diagnosed with acute OVCF of the thoracic spine after using an EAMC. The patient had no risk factor for fragility fracture and experienced an abrupt onset of severe upper back pain while using EAMC. Imaging studies revealed an isolated acute compression fracture at T8 vertebra (AO classification type A1) while dual-energy X-Ray absorptiometry scan confirmed osteoporosis. The patient was treated with a plastic orthosis and oral medications for osteoporosis. After 6-months follow-up, the patient showed union of the fractured T8 vertebra and no remaining symptoms. This case highlights that OVCF can be induced by EAMC. Therefore, patients with or at risk for osteoporosis should be cautious while opting for deep tissue massage using EAMC.

Background:Single or combined multiple-site peripheral nerve blocks (PNBs) are becoming popular for patients undergoing surgery on their feet or ankles. These procedures are known to be generally safe in surgical settings compared with other forms of anesthesia, such as spinal block. The purposes of this study were to assess the incidence of complications after the administration of multiple PNBs for foot and ankle surgery and to compare the rates of complications between patients who received a single PNB and those who received multiple blocks.Methods:Charts were reviewed retrospectively to assess peri- and postoperative complications possibly related to the PNBs. The records of 827 patients who had received sciatic nerve blocks, femoral nerve blocks adductor canal blocks, or combinations of these for foot and/or ankle surgery were analyzed for complications. The collected data consisted of age, sex, body mass index, presence of diabetes mellitus, smoking history, tourniquet time, and complications both immediately postoperatively and 1 year later.Results:Of these 827 patients, 92 (11.1%) developed neurologic symptoms after surgery; 22 (2.7%) of these likely resulted from the nerve blocks, and 7 (0.8%) of these were unresolved after the patients’ last follow-up visits. There were no differences in complication rates between combined blocks and single sciatic nerve blocks.Conclusion:There were more complications, both transient and long term, after anesthetic PNBs than previous literature has reported. Combined multiple-site blocks did not increase the rate of neurologic complications.Level of Evidence:Level III, retrospective comparative study

STUDY DESIGN Case-control study. OBJECTIVE To investigate the clinical and radiological outcomes of pedicle screw removal after successful fusion of thoracolumbar burst fractures. SUMMARY OF BACKGROUND DATA Implant removal is a common procedure in orthopedic surgery, although the benefits of and indications for removal remain controversial. Previous studies on pedicle screw removal have reported conflicting outcomes, because the study subjects and surgical goals were heterogeneous in nature. METHODS We studied 45 consecutive patients who underwent implant removal and a control cohort of 45 age- and sex-matched patients who retained their spinal implants after successful posterior fusion of thoracolumbar burst fractures using pedicle screw instrument. In most cases, long-segment instrumentation with short-segment posterior fusion was performed. The mean elapsed period prior to implant removal after index fracture surgery was 18.3 ± 17.6 months. A visual analogue scale for back pain was applied, the Oswestry disability index calculated, and radiological parameters derived at the time of implant removal and 1 and 2 years postoperatively obtained. These data were compared with those of the control group evaluated at the same times after index fracture surgery. RESULTS Patient demographics, mechanisms of injury, fracture morphologies, and the outcomes of index fracture surgery were similar between the 2 groups. The mean visual analogue scale and Oswestry disability index scores were better at both the 1- and 2-year follow-ups in the implant removal group than in the control group (all P values = 0.000). The segmental motion angle of the implant removal group was 1.6° ± 1.5° at the time of implant removal, and increased significantly to 5.8° ± 3.9° at 1-year follow-up (P = 0.000), and was maintained at this level at the 2-year follow-up (5.9° ± 4.1°) (P = 0.000). CONCLUSION In patients treated successfully for thoracolumbar burst fractures, pedicle screw removal is beneficial because it alleviates pain and disability. Restoration of the segmental motion angle after implant removal may contribute to the clinical improvement. LEVEL OF EVIDENCE 3.

Study design A retrospective case-control study. Objective To evaluate the safety and efficacy of the ventral epidural filling technique in lumbar interlaminar epidural steroid injection (ESI). Summary of background data The ventral epidural space can be a preferred target in ESI because it contains many spinal pain generators. However, there have been few studies regarding the ventral epidural space filling technique in interlaminar ESI. Methods This study involved a retrospective analysis of 150 consecutive patients treated with the ventral epidural filling technique in interlaminar ESI (ventral ESI) and a control cohort of 150 consecutive patients treated with the dorsal epidural filling technique in interlaminar ESI (conventional ESI). The visual analogue scale for leg pain, the visual analogue scale for back pain, and the Oswestry Disability Index were compared at preinjection and 2 weeks, 6 weeks, 6 months, and 1 year postinjection. The groups were compared with regard to repeated injection or surgery within 1 year after the initial procedure. The fluoroscopic time and the procedure-related complications including severe pain (visual analogue scale score>7) during injection, dural puncture (subdural contrast spread), headache, neurological symptoms, and infection were also compared. Results There were no significant differences in leg pain, back pain, or Oswestry Disability Index improvement at each visit between the ventral ESI group and the conventional ESI group (all P>0.05). The numbers of repeat injections and surgical procedures were not significantly different between 2 groups (P=0.262 and 0.385, respectively). There were no significant differences in severe pain at injection (P=0.326), dural puncture (P=0.428), headache (P=0.393), neurological symptom (P=0.419), or infection (P=0.500) between the 2 groups. The fluoroscopic time was significantly shorter in ventral than in conventional ESI (P Conclusion The ventral epidural filling technique can be performed safely and more easily during lumbar interlaminar ESI. The clinical results and procedure-related complications with this technique were comparable with those seen with conventional interlaminar ESI. Level of evidence 3.

Oblique lateral interbody fusion (OLIF) L5–S1 is essentially to perform an anterior lumbar interbody fusion (ALIF) in the lateral position. Because the surgical procedures are performed “obliquely” over the left common iliac vein (LCIV), ensuring that the vein is protected which is particularly important. We aimed to evaluate the configuration of LCIV and its risk of mobilization during anterior approach at L5–S1 segment. This study involved 65 consecutive patients who underwent anterior lumbar fusion (ALIF, n = 39; OLIF, n = 26) at the L5–S1 segment. Three independent examiners evaluated the configuration of the LCIV at the L5–S1 disc on axial magnetic resonance images of the lumbar spine. The LCIV was categorized into three types according to the difficulty of mobilization: type I (no requirement for mobilization; LCIV runs laterally for more than two-thirds of the length of the left side of the L5–S1 disc), type II (easy mobilization; LCIV obstructs the L5–S1 disc space, but the perivascular adipose tissue is present under the LCIV), and type III (potentially difficult mobilization; no perivascular adipose tissue under the LCIV). The patient records were reviewed for vascular complications. There were 21 men and 44 women in this study, with a mean age of 63.4 years (range 19–83 years). Type I LCIV configuration was found in 32 (49.2%) patients, type II in 18 (27.7%), and type III in 15 (23.1%). There were 7 (10.8%) patients with LCIV injury (type I, n = 0; type II, n = 2; type III, n = 5) (P = 0.003). Intraobserver reliability for the LCIV classification ranged from substantial to excellent, and interobserver reliability ranged from moderate to excellent. Preoperative evaluation for anterior approach to the L5–S1 segment should take account of the LCIV position, as well as the difficulty of its mobilization. The type III LCIV configuration showed a high rate of vascular injury.

Study design This is a retrospective control study. Objective We aimed to determine whether preexisting cervical disk degeneration is a prognostic factor in Whiplash-associated disorder (WAD). Summary of background data WAD is a common injury of traffic accident and has a broad range of prognoses. Although numerous studies have investigated prognostic factors in WAD, few have evaluated the effect of preexisting disk degeneration. Materials and methods This study involved 45 consecutive patients with grade I or II WAD having advanced disk degeneration (at least 1 disk of Miyazaki grade≥III on magnetic resonance imaging) and a control cohort of 52 patients with no or mild disk degeneration (all disks having Miyazaki grades≤II). Clinical assessment included pain severity (assessed by the visual analog scale), neck pain-related disability (assessed by the neck disability index), and physical and mental health condition [assessed by the short-form 36 (SF-36) physical composite score and SF-36 mental composite score, respectively]. Changes in each parameter were evaluated at baseline and at 3-month, 6-month, and 1-year follow-ups and compared between the 2 groups. Results There were no differences between the 2 groups regarding demographics and baseline outcome parameters (all P>0.05). There were also no differences in improvement in visual analog scale for neck pain, neck disability index, SF-36 physical composite score, or SF-36 mental composite score between the 2 groups (all P>0.05) for each visit. The number of claim closures was significantly lower among patients with advanced degeneration than among controls at 6-month and 1-year follow-ups (P=0.004 and 0.006, respectively). Conclusions In the present study, the clinical presentation and prognosis of WAD were not affected by preexisting disk degeneration. However, claim closure was delayed in patients with preexisting disk degeneration. These results suggest that misunderstanding of disk degeneration on magnetic resonance imaging may create persistent illness and lead to continued compensation in WAD.

BACKGROUND CONTEXT A fall from a height is the one of common causes of thoracolumbar fractures. In most cases, falls from a height are accidental. However, some are the intentional fall for suicidal attempt. Although there may be the different clinical features between suicidal attempters and accidental fallers, there have been few literature reviews comparing them. PURPOSE We analyzed the demographic and the radiological characteristics between suicidal attempters and accidental faller. STUDY DESIGN/SETTING This is a retrospective comparative clinical study in an academic institutional setting. PATIENT SAMPLE Between March 2011 and June 2018, we evaluated 78 consecutive patients (under 40 years old) who suffered unstable traumatic thoracolumbar fractures and were treated surgically in one trauma center. Patients were classified into suicidal group (suicidal attempters, n=30) and non-suicidal group (accidental fallers, n=48) by interviewing patients or inspector of accident. Psychiatrist helped to distinguish these patients. OUTCOME MEASURES Demographic data including gender, age, past history of psychiatric disease, the height of fall, neurological status, associated injuries and treatment were obtained from the medical records. We also reviewed the location and the numbers of fractured vertebrae. METHODS We compared theses parameters between suicidal group and non-suicidal group. RESULTS There were significant differences in gender, age, past history of psychiatric disease and associated injuries (all p CONCLUSIONS There were distinct characteristics of patients with thoracolumbar fractures between suicidal and non-suicidal groups regarding gender, age, past history of psychiatric diseases and associated injury. Patients as suicidal attempters were younger and female-dominant. Psychiatric diseases, especially schizophrenia and major depression disorder, were more common in suicidal attempters. Severe associated injury in pelvis is more common in suicidal attempters. FDA DEVICE/DRUG STATUS This abstract does not discuss or include any applicable devices or drugs.