Purpose
Thoracolumbar vertebral compression fractures (VCFs) are a leading cause of kyphosis and related biomechanical complications, often resulting in chronic back pain and reduced function. Balloon kyphoplasty has been widely used as a minimally invasive intervention to provide pain relief and restore vertebral height. The SpineJack system is a relatively novel technique that introduces mechanical distraction, offering potentially enhanced vertebral restoration. This study aims to compare these two effective treatments for thoracolumbar fractures.
Materials and Methods
This study analyzed 30 patients with thoracolumbar VCFs surgically treated, using the Spine-Jack system (n=10) or balloon kyphoplasty (n=20). Back pain was evaluated as VAS pain score and functional disability was assessed with Oswestry Disability Index (ODI) preoperatively and immediately postoperatively. Radiological outcomes were measured on plain lateral X-rays, including vertebral height restoration, segmental kyphosis angle, and sagittal vertical axis (SVA). Complications, such as cement leakage and adjacent vertebrae fractures, were recorded. Continuous variables – with t-tests and categorical variables- with chi-square tests, were analyzed. P-value less than 0.05 was considered statistically significant.
Results
Both the Spine-Jack system and balloon kyphoplasty were effective in reducing back pain and improving patients’ function, with significant improvements in VAS and ODI scores. However, the Spine-Jack system demonstrated superior vertebral height restoration (85% vs. 72%, p=0.03) and segmental kyphosis angle correction (12° vs. 9°, p=0.032) when compared to balloon kyphoplasty. Complication rates were all low and comparable between the two groups.
Conclusions
Although the Spine-Jack system and balloon kyphoplasty are all effective for thoracolumbar VCFs, the Spine-Jack system offered superior radiological outcomes in selected cases. Further studies may explore their complementary roles in managing thoracolumbar VCFs.

The standard method for treating posterior pelvic ring injuries involves sacroiliac joint cannulated lag screw fixation, necessitating repeated fluoroscopy and leading to radiation exposure. The O-arm navigation system, designed for spine screw fixation, is applied in pelvic injuries to enhance precision. A successful case involved a 39-year-old male with a complex pelvic injury, where sacroiliac screw fixation was performed in the prone position using the O-arm guide. The patient, injured at a construction site, showed fractures and widening of the symphysis pubis and right sacroiliac joint. Surgery was planned for both lumbar and pelvic regions due to an L3 burst fracture. The O-arm system demonstrated efficacy in precise screw placement, reducing surgical duration, and minimizing complications. The discussion emphasizes early pelvic fixation benefits, with percutaneous iliosacral screws standing out. Conventional fluoroscopy-guided methods pose challenges, and the O-arm system proves advantageous, especially for less experienced surgeons. Future advancements may enable pelvic surgery using the O-arm without C-arm guidance if instrumentation for pelvis fixation is developed.

Objective
The purpose of this study is to investigate the radiological risk factors and differences in spinopelvic parameters for radiologic degenerative changes in the sacroiliac joint after lumbar or lumbosacral fusion surgery.
Materials and Methods
From 2019 to 2020, 116 patients diagnosed with lumbar and sacral degenerative diseases who underwent lumbar or lumbar sacral fusion were included. The degenerative changes of the sacroiliac joint were measured by CT performed before and 6 months after surgery, and divided into two groups according to the presence or absence of radiographic degeneration. Evaluation factors for radiographic degeneration include sclerotic changes, erosion, osteophyte formation, intra-articular bone formation, joint space narrowing, intra-articular gas formation and subchondral cysts were evaluated. Spinopelvic radiologic parameters and surgery-related parameters including lumbar lordosis, sacral slope, pelvic incidence, global tilts, and T1PA between the two groups were analyzed using Student's t-tests and chi-square tests to determine the difference between continuous and non-continuous variables between groups. Logistic regression analysis was used for the analysis of risk factors for degeneration for SI joints after lumbar or lumbosacral fusion surgery.
Results
There was no statistically significant difference between the demographic data and surgery-related data between the group with and without sacroiliac joint degenerative changes. There was also no statistical difference in the rate of degenerative changes in the sacroiliac joint according to the presence or absence of S1 in the fusion segment. (degeneration group vs non-degeneration group; 45.5% vs 39.8%, p: 0.574) There were statistically significant differences between the two groups in lumbar lordosis (LL), pelvic angle of incidence (PI), and PI-LL. (LL; 27.2±12.0 vs. 39.8±11.3, PI; 51.3±12.0 vs. 57.2±12.6. and PI-LL; 24.1±17.0 vs 17.4±13.9, p: <0.001, 0.023, and 0.030) As risk factors for radiographic degenerative changes in the sacroiliac joint, lumbar lordosis (LL), pelvic incidence (PI), sacral inclination (SS), and sagittal vertical axis (SVA) were statistically significant factors. (lumbar lordosis Odd ratio: 0.851, 95% CI: 0.791-0.917, p-value <0.001)
Conclusions
Lumbar lordosis and pelvic incidence are related as risk factors for radiographic degenerative changes in the sacroiliac joint after surgery in patients with lumbar spinal fusion.

Objective
To investigate the association of quantitative paraspinal muscle measurements to the Oswestry disability index (ODI) in patients with lumbar spondylolisthesis.
Materials and Methods
Ninety two patients (mean age, 61.6 years; male, mean age, 71.8 years ; female; mean body mass index [BMI], 24.9 kg/m² ) who had undergone lumbar fusion due to spondylolisthesis with available selfcompleted postoperative ODI were included. The total cross-sectional area (CSA) and functional CSA (FCSA; i.e., area containing only lean muscle tissue) of the paraspinal muscle group (multifidus and erector spinae muscles) and the psoas muscles were measured at L2–L3, L3–L4, and L4–L5 disc levels each on preoperative magnetic resonance imaging (MRI) and the sum of areas at each level served as representative values for each muscle. The FCSA/total CSA ratio and the skeletal muscle index (SMI=muscle area [cm² ]/patient height2 [m² ]) were calculated. Pearson’s correlation analyses were performed to evaluate the relationship between preoperative paraspinal muscle measurements and postoperative ODI.
Results
Quantitative values of low paraspinal muscle showed significant correlation with high ODI values. As a result of this study, the preoperative paraspinal muscle was quantified in the group of patients undergoing spinal fusion. Patients with low value in CSA and FCSA of paraspinal muscle could observe the tendency to transition to low clinical outcomes. Therefore, quantitative values of surrounding muscles are factors affecting clinical outcomes of patients undergoing spinal surgery Conclusion: Smaller muscle bulk (total CSA) of psoas muscles and lean muscle mass (FCSA) of paraspinal muscle group and psoas muscles combined on preoperative MRI were associated with significant postoperative disability based on ODI in patients with lumbar spondylolisthesis.

Purpose
To evaluate and analyze the clinical results of lumbar microdiscectomy using minimally invasive tubular retractor between recurrence and non-recurrence group, and to assess the merits of minimally invasive spinal surgery. Overview of Literature: No large registry study has so far investigated the clinical results of lumbar microdiscectomy using minimally invasive tubular retractor.
Methods
From July 2003 to April 2011 we retrospectively studied a consecutive series of 156 patients who underwent lumbar microdiscectomy using minimally invasive tubular retractor. The following data were collected: clinical outcomes, operative time, intraoperative blood loss, recurrence, and complications. The clinical outcomes were measured using a visual analog scale (VAS) and assessed by the modified MacNab criteria.
Results
Minimally invasive tubular microdiscectomy was performed in 156 patients. The clinical outcomes assessed by MacNab criteria were excellent in 63 patients (40%), good in 71 patients (45%). VAS scores of low-back pain decreased from a mean of 6.7 prior to surgery to 2.5 after surgery, and that of leg pain decreased from 7.2 to 2.1. The average operative time was 68 minutes (range, 25 to 180 minutes). The average blood loss was 42 mL (range, 0 to 500 mL). None of the patients needed blood replacement. One patient had wound infection problem but there was no dural tear case. Twenty-two patients had recurrence. Average time to recurrence was about 42 months. Seventeen cases recurred at the same level and five cases recurred at the adjacent level. Eleven cases in 22 patients with recurrence were contained disc type and the others were non-contained disc type. Eighteen cases in 22 patients with recurrence were paracentral disc herniation type and the others were far lateral type. Average body mass index (BMI) of recurrence cases was 24.7 (range, 17.5 to 31.3) and that of non-recurrence cases was 24.5 (range, 16.3 to 39.2).
Conclusions
Lumbar microdiscectomy using tubular retractor can offer a useful modality for the treatment of lumbar herniated disc with the merits of minimally invasive spinal surgery. Further randomized, prospective investigations are needed to fully evaluate the impact of this technique.

Far lateral lumbar disc herniation (FLLDH) is a rare type of intervertebral disc herniations based on its anatomical location. A herniated lesion compressing the exiting nerve root superiorly makes clinical symptoms of lumbar radiculopathy. We report a 77-year-old female patient presenting lower back pain, left buttock pain and numbness, radiating pain, tingling sensation on the left lower extremity. Radiological images revealed a 16.2x13.8x7.2 mm sized mass like lesion outside the left foraminal canal of the L5-S1 disc space, mimicking nerve sheath tumor at a extradural location. Histopathological examination of the specimen was confirmed as a sequestrated disc fragments. We conclude that preoperative careful evaluation should be exercised for the differential diagnosis of the extraforaminal soft mass.

We reviewed literatures relating to minimally invasive lateral lumbar interbody fusion for the treatment of adult degenerative spinal deformity. Most of literatures were retrospective case series with a small numbers of patients. A prospective multicenter study was published in two separate papers. This procedure was effective in treating the coronal deformity. On the other hand, restoring the sagittal plane remains an issue. Pseudarthrosis was problematic, especially in the cases without use of the human recombinant bone morphogenetic protein-2 (rhBMP-2) and bilateral pedicle screw fixation. Temporary sensory deficits and transient leg weakness was the most common complication after lateral lumbar interbody fusion. Careful patient selection is important for the application of lateral minimally invasive techniques for adult degenerative scoliosis.

Purpose
The purpose of the study was to investigate the effect of obesity on the accuracy of percutaneous pedicle screw placement.
Materials and Methods
We performed a retrospective analysis on the first 89 patients undergoing minimally invasive lumbar fusion with percutaneous pedicle screw placements for the treatment of degenerative lumbar spinal disorder. Based on patient’s body mass index (BMI), patients were divided into 3 groups: group 1 – normal weight (BMI<25, 38 patients, 157 screws); group 2 – overweight (25≤BMI<30, 29 patients, 124 screws); group 3 – obese (BMI≥30, 22 patients, 89 screws). Using postoperative computed tomography (CT) scans, the position of placed screws to the pedicle or anterior body perforation was evaluated using the following grading method: Grade A, completely in the range without pedicle cortex violation; Grade B, pedicle wall violation<2 mm; Grade C, pedicle wall violation 2 to 4 mm; and Grade D, pedicle wall violation>4 mm.
Results
Among the 370 pedicle screws, 308 screws (83%) were perfectly placed within the pedicle. Among the 62 misplaced screws, 45 screws were grade B pedicle breaches (73%, 45/62), and 45 screws were misplaced in lateral direction (73%, 45/62). 36 screws (10%) perforated the anterior vertebral cortex. Twenty eight screws were misplaced in overweight group, 12 screws in obese group, and 22 screws in normal weight group. With the number of screws available, subgroup analysis did not reveal a significant difference in the grade (p=0.10) or the direction (p=0.97) of pedicle breaches among groups.
Conclusion
Our data suggest that obesity does not affect the accuracy of percutaneous pedicle screw placement. We do not hesitate or deny the surgery because of patient’s heavy body habitus, which seems to be a apparent benefit of minimally invasive spinal surgery.

Protecting cranially located facet joints during pedicle screw placement is one of the modifiable factors that could prevent possible adjacent level problems related with spinal fusion procedure. Placing pedicle screws percutaneously appears to be more challenging in the technical aspect than performing with traditional open technique because of its limited selecting entry point for screw placement. The authors have reported surprisingly higher incidence and risk factors of cranial facet joint violations by percutaneously placed pedicle screws. The purpose of this literature was to illustrate the surgical technique focusing on the tips to avoid cranial facet joint violation during percutaneous placement of pedicle screws.