Introduction: The thoracolumbar junction (TLJ) presents considerable anatomical challenges during spinal surgery, often requiring access through the chest cavity or diaphragm. Conventional approaches have inherent limitations, including increased morbidity and technical difficulties owing to the substantial distance from the skin incision to the vertebral body and interference from the ribs, leading to ergonomic challenges. We developed a Reverse Oblique Approach (ROA) to address these issues.

Methods: We conducted a retrospective comparative study involving 38 patients who underwent either corpectomy or lateral interbody fusion (LIF) at the TLJ using either a conventional or Reverse Oblique Approach. Individuals with thoracolumbar pathologies requiring anterior access were included in the study. We evaluated the operative time and the incidence of parietal pleural injury.

Results: In the corpectomy cohort, six patients underwent conventional approaches, while six patients underwent the Reverse Oblique Approach. Despite the greater complexity of surgeries in the ROA group, the mean operative time was shorter (183.66±20.89 minutes) compared to the conventional group (211.17±25.34 min), though the difference was not statistically significant (P = 0.18). Parietal pleural injury occurred in 50% of the patients in the conventional group compared to 16.7% in the ROA group.

In the LIF cohort, 13 patients underwent conventional approaches and 13 underwent ROA. The ROA group had a significantly shorter mean operative time (140.31±52.13 min) compared to the conventional group (174.92±29.72 min; P = 0.048), with no significant difference in the number of levels operated (P = 0.68). Postoperative pleural effusion was observed in 46.2% of the patients in the conventional group and in 30.8% of the patients in the ROA group. One case of permanent left phrenic nerve palsy was observed in the control group.

Conclusions: The Reverse Oblique Approach is a viable alternative to conventional techniques for TLJ surgery, resulting in a reduced operative time, lower rates of pleural injury, and fewer postoperative complications, even in complex cases. These findings suggest that ROA may serve as a valuable minimally invasive approach to achieve a favourable balance between operative accessibility and surgical safety.

Introduction: Since the introduction of the surgeon-controlled mode of the Cirq^® robotic system in our hospital, we have used it for minimally invasive surgery (MIS) with a posterolateral approach for cervical posterior instrumentation. In this study, we discuss the advantages of this technique (group R) over fluoroscopy-guided conventional open techniques (group O) performed before the introduction of the robotic system for C1-C2 posterior screw fixation.

Methods: Group R consisted of 64 screws in 16 patients and group O consisted of 70 screws in 18 patients; the two groups showed no statistical difference in age, sex ratio, indication for instrumentation, operative time, or blood loss.

Results: As evidenced by postoperative CT scans, clinically acceptable screw placement (breach < 2 mm) accounted for 61 of 64 screws (95.3%) in group R and 67 of 70 screws (95.7%) in group O, without a significant difference between the groups. Each group had 3 screws of breach ≥ 2 mm; 3 screws of grade 2 (breach ≥ 2 mm and ≤ 4 mm) in group R, 2 deviating superiorly and 1 medially, while 2 screws of grade 2 and 1 screw of grade 3 (breach > 4 mm) in group O, all 3 deviating medially. Compared with group O, group R had significantly greater inclination angles (p < 0.0001) of lateral-to-medial screw trajectories in the transverse plane for both C1, indicating better safety from vertebral artery (VA) injury in group R than in group O.

Conclusion: For C1-C2 posterior instrumentation, robot-assisted MIS eliminates morbidity-prone soft-tissue dissection, radiation exposure to the surgical team, and human error. As an additional benefit, MIS with the posterolateral approach allows for sufficiently large inclination angles of the lateral-to-medial screw trajectories without counterpressure of the retracted muscles, resulting in better safety from VA injury. This technique also minimises the navigation pitfall of "untracked pressure-induced vertebral rotation" because the muscles and ligamentous complex are undetached from the bone. Pitfalls occur when the surgeon applies pressure to the spine during probing, drilling, tapping, and screwing, which causes the vertebra to rotate relative to the patient reference array.

The entry point for the screw placed at C1 with our technique lies at the base of the transverse process associated with a new screw trajectory distinct from those previously described by Tan et al. and Goel et al. as well as the notching technique.

Introduction: Dural arteriovenous fistulas (dural AVFs) and epidural arteriovenous fistulas (epidural AVFs) are spinal vascular malformations that cause venous hypertension due to arteriovenous shunting, leading to myelopathy. Although surgical interruption of the draining vein is an effective treatment, the differences in surgical outcomes based on anatomical location remain unclear. This study aimed to compare surgical outcomes between thoracic and lumbar AVFs.

Methods: A total of 28 patients (20 males, 8 females; mean age at surgery, 68 years) who underwent surgical treatment for AVFs in the thoracic or lumbar spine at our hospital from May 2011 to June 2023 were included. Patients were divided into two groups based on the location of the arteriovenous shunt: the thoracic group (n=13) and the lumbar group (n=15). Group comparisons were performed with statistical significance set at p < 0.05.

Results: All 13 cases in the thoracic group had dural AVFs with dorsal dural penetration of the draining vein. In contrast, 14 of the 15 cases (93%) in the lumbar group had epidural AVF, and 13 of 15 cases (87%) exhibited ventral dural penetration of the draining vein (p < 0.001). The median operation time was significantly longer in the lumbar group (230 minutes) than in the thoracic group (147 minutes) (p < 0.05), while the median intraoperative blood loss did not significantly differ between the groups (thoracic vs. lumbar groups, 100 ml vs. 160 ml, respectively; p = 0.18). Two cases in the lumbar group required revision surgery due to failure to interrupt the draining vein during the initial procedure. In both groups, magnetic resonance imaging findings, gait function, and bladder function significantly improved and were maintained until the final follow-up.

Conclusions: Surgical outcomes were favorable in both the thoracic and lumbar groups. However, the lumbar group exhibited a higher incidence of epidural AVFs with varying dural penetration sites of the draining vein, complicating identification and interruption. Therefore, lumbar AVFs necessitate more careful assessment and surgical planning compared to thoracic AVFs.

Purpose: To compare three-dimensional preoperative simulation performed for anterior decompression of the ossification of the posterior longitudinal ligament (OPLL) with the conventional method.

Method: Using 3D reconstruction created from preoperative computed tomography (CT) volume data, a simulation movie was created to confirm the coronal section CT reconstruction of the decompression area from the vertebral surface to the spinal canal, as in real surgery, and referred to intraoperatively. Patients who underwent anterior decompression for cervical OPLL with corpectomy were included in this study. A comparison was made between 18 patients in the conventional group using CT-reconstructed coronal sections and 17 patients in the 3D group using this method. We also investigated lateral-type subgroups. Surgical invasion, insufficient decompression, and complications were also examined.

Results: No significant differences were observed in surgical invasion or complications between the two groups. Seven cases of insufficient decompression were observed in the conventional group and 0 in the 3D group (p<0.01). In the lateral-type subgroup, cerebrospinal fluid leakage occurred in 6 cases in the conventional group and 3 cases in the 3D group, indicating a statistically significant difference (p<0.05).

Conclusions: This method improved the accuracy of OPLL anterior decompression compared to the conventional method. This method allowed for accurate and efficient decompression without increasing invasion and was effective in lateral-type OPLL cases. This method has the advantage of not requiring the initial cost of expensive equipment, such as intraoperative navigation and can be used regardless of the facility.

Purpose: This study aimed to identify the risk factors of cage subsidence in single-level anterior cervical discectomy and fusion (ACDF) with stand-alone cages.

Methods: Fifty-two patients who were followed-up for at least 6 months after surgery were included (28 in the stable group and 24 in the subsidence group). Subsidence was defined as a decrease in intervertebral height of 2 mm or more at the last observation compared to immediately after surgery. We considered the following risk factors for subsidence: osteoporosis, cage size, excessive endplate resection, and dorsal placement of the cage (dorsal placement was defined as the tip of the cage being > 2 mm dorsal to the anterior vertebral body). Characteristics of patients with dorsal placement were also investigated.

Results: Osteoporosis and dorsal cage placement were the two risk factors that reached statistical significance in univariate analysis. Both were independently and statistically significant risk factors in the logistic regression. Three posterior cage placement patterns were noted. First, both the upper and lower vertebrae were normal (incidence: 11.5% (6/52 cases), of which 50% subsided). Second, the angle between the anterior wall of the upper vertebra and the terminal plate was less than 70° (11.5% and 100%, respectively). Third, the anterior margin of the lower vertebra was blunted (11.5% and 66.7%, respectively).

Discussion: Osteoporosis and dorsal cage placement were identified as risk factors for cage subsidence in this study. The latter is caused by the characteristic vertebral body shape. Our findings may be helpful when considering the indications for cage-stand-alone ACDF.

Introduction: The utility of sagittal flexible screws (SFS) for the prevention of PJK after surgery for adult spinal deformity (ASD) was evaluated.

Subjects and Methods: Patients who underwent cMIS using LLIF and PPS for ASD at our hospital after 2023 who were followed up for at least 12 months were included in this study. We evaluated the spinopelvic parameters, rod contour angle (RCA), pedicle screw angle (PSA), rod screw angle (RSA), PJK/PJF incidence, UIV/UIV-1 angle (UIVA), and the difference between UIVA in sitting and supine positions (UIVM) in the S group, which used SFS for UIV, and the NS group, which did not use SFS for UIV. UIVA was defined as the angle between the UIV cephalic endplate and the UIV-1 caudal endplate, RCA was defined as the posterior curvature angle of the rod from the UIV to L1, and PSA was defined as the angle between the cephalic endplate of the UIV and the screw.

The RSA was defined as the angle between the rod and screw in the UIV.

Results: No significant differences were observed between the two groups in terms of patient background, ODI, or spinopelvic parameters. Additionally, no significant differences were observed in the RCA, PSA, and RSA. Although no significant differences were present in postoperative UIVA, UIVM was 2.2° in the S group and 0.5° in the NS group, showing a significant difference. No significant difference was observed in the incidence of PJK/PJF or screw loosening between the two groups.

Conclusion: The results of this study indicate that SFS can tolerate slight movement of the UIV after surgery, and that a gradual transition from the fixed vertebra to the non-fixed vertebra may be achieved. Although no significant difference was observed in the incidence of PJK and screw loosening, the results suggest that this gradual transition effect from the fixed vertebra to the non-fixed vertebra may be useful for preventing degeneration at the adjacent disc level in the long term.

Introduction: We examined the utility of cement augmentation pedicle screws (CAPS) in lateral access corpectomy (LAC) for osteoporotic vertebral collapse (OVC).

Subjects and Methods: Twenty-five patients with OVC who underwent minimally invasive anterior and posterior reconstruction using LAC and percutaneous pedicle screw (PPS) fixation were included. All procedures were performed by the same surgeon at our institution. Patients who could be followed up for at least 2 years were included in this study. The mean patient age was 73.5 years, and mean follow-up period was 38.4 months. Patients were divided into two groups: those with CAPS (Group C) and those without CAPS (Group NC). We examined the number of fixed vertebrae, various parameters, Oswestry Disability Index (ODI), volume of cement injected, and complications.

Results: No significant differences were observed in patient demographics between the groups. However, the number of fixed vertebrae was significantly higher in the Group NC. Although spinopelvic parameters exhibited no significant differences, Group NC demonstrated a significant correction loss in local alignment. In both groups, ODI scores improved significantly after surgery. The average cement volume injected was 3.8 mL at the thoracolumbar junction and 5.4 mL in the middle and lower lumbar spine. No significant differences were observed in the bone fusion rates. However, screw loosening and cage subsidence were more frequent in the Group NC.

Conclusion: The use of CAPS combined with LAC reduced the fixation range without increasing complications.

Introduction: We encountered a case of a spinal hemangioblastoma whose magnetic resonance imaging (MRI) findings were preoperatively misidentified as ependymoma.

Case Report: A 23-year-old male patient presented with decreased grip strength. MRI showed a homogeneously enhanced tumour circumferentially surrounded by spinal cord parenchyma at C5-6; it was diagnosed as an ependymoma. When the posterior median sulcus was opened, a reddish tumour appeared. It was rich in blood flow and bled easily, which was incompatible with the characteristics of an ependymoma. Meticulous cauterization and dissection of the cord parenchyma were repeated for en bloc removal, and the attachment to the anterior median septum and the feeding arteries were divided. The pathological diagnosis was a hemangioblastoma.

Conclusions: The hemangioblastomas located in the centre of the cord were atypical. Intraoperative findings showed that the tumour originated from the anterior median septum. Surgery required different procedures for the preoperative diagnosis of ependymoma.

A 62-year-old female incidentally discovered a giant tumour occupying the spinal canal during a urology consult. The spinal tumour extended from T11-12 to L 3, protruding from the right L2-3 intervertebral foramen into the retroperitoneal cavity and paravertebral muscles. The CT showed that the L1-L3 pedicles and L2 vertebral body were thinned because of bony resorption. The diagnosis was giant invasive spinal schwannomas (GISS).

Treatment was a three-stage surgery:

First-stage surgery: Laminectomy from T10 to L4, resection of the right L2-L3 intervertebral foramen, and resection of the intradural and intraforaminal tumours.

Second-stage surgery: Tumour resection from the right retroperitoneal cavity.

Third-stage surgery: Insertion of a cage into the intervertebral space with anterior screw fixation using a left lateral approach.

Outcome: Gross total resection of the tumour.

Postoperative Course: Histopathological examination confirmed schwannoma. Bone fusion was achieved in the L2-L3 intervertebral space at one year postoperatively with no tumour recurrence.

We report this case in a review of the literature.

Introduction: We report a rare case of idiopathic spinal herniation (ISCH) with an unusual course.

Case Presentation: A 56-year-old male presented with urinary incontinence and weakness in the left lower limb. Magnetic MRI of the thoracic spine suggested ventral displacement of the spinal cord at the T2 vertebral level, raising the suspicion of an extradural escape of the spinal cord. The patient was diagnosed with ISCH at the T2 level and was scheduled for surgery. During the procedure, we observed a direct extradural escape of the spinal cord ventrally. Following the reduction of the herniated tissue, we also directly sutured the herniation defect. Postoperatively, the patient's symptoms improved and his condition stabilised. However, 4 years and 2 months later, the patient returned with complaints of gait disturbance and decreased strength in the left lower limb. Magnetic resonance imaging (MRI) revealed ventral displacement of the spinal cord at the T2 level, indicating recurrence of the spinal herniation. Surgical revision was decided. Upon incision of the dorsal dura, we found a cystic mass extending cephalad and caudad. The site of the previous suturing did not show any herniation recurrence. However, new evidence of spinal cord entrapment was identified caudally. After reducing the entrapped spinal cord, the outer layer of the dura mater was observed through a defect in the inner layer. We directly sutured the herniation defect in the inner layer and reinforced it with a covering material before surgical closure.

Conclusion: This case report illustrates the consequence of continuous dorsal pressure on the spinal cord from a cystic mass that developed postoperatively, resulting in a defect in the intrinsically vulnerable ventral dura mater and the formation of a new spinal herniation.

Introduction: Spinal subdural haematomas are relatively rare and believed to be caused by blood disorders, antithrombotic therapy, vascular malformations, and iatrogenic factors, such as lumbar puncture. Here, we report three cases of chronic subdural and spinal subdural haematomas complicated by craniotomy.

Case 1: A 56-year-old man presented with a spinal subdural haematoma during fluid replacement treatment for chronic subdural haematoma due to hypotension.

Case 2: An 87-year-old man presented with a spinal subdural haematoma three days postoperatively for chronic subdural haematoma.

Case 3: A 74-year-old woman presented with a spinal subdural haematoma three days after cerebral aneurysm clipping.

Discussion and Conclusion: Although spinal subdural haematoma related to intracranial haematoma is rare, treatment of spinal subdural haematoma must be considered.

Introduction: Selecting an appropriate surgical technique for spinal fusion can be challenging when an infection is suspected within the planned fixation area. We report a case in which effective treatment was achieved by performing Pedicle Subtraction Osteotomy (PSO) at the site of infection, combined with dual intrasacral buttress screws (ISBS).

Case Report: A 64-year-old male developed a surgical site infection following lumbar discectomy at another hospital, which was managed conservatively with antibiotics. Two years postoperatively, the patient experienced worsening lower back and left lower limb pain, which hindered his return to work. Imaging revealed L4/5 foraminal stenosis and kyphotic deformity due to vertebral body changes, while blood tests suggested persistent low-grade infection. The patient underwent L5 PSO with a dual ISBS placement. Postoperatively, his symptoms improved, and spinal alignment was successfully corrected.

Conclusion: For foraminal stenosis and local kyphotic deformities of the lower lumbar spine secondary to postoperative infection, L5 PSO combined with dual ISBS provided effective stabilisation and deformity correction without recurrence of infection, resulting in favourable clinical outcomes.

Introduction: Ultrasound technology allows real-time visualisation of needle placement near a nerve and the spread of a local anaesthetic solution around it. In this study, we explored the feasibility of long-axis ultrasound imaging for hydrodissection of the pudendal nerve (PDN).

Methods: This was a retrospective case series involving seven patients with a tentative diagnosis of PDN entrapment. Each patient underwent ultrasound-guided PDN hydrodissection. After obtaining transverse images of the ischial spine, a low-frequency convex probe was slightly rotated to capture the PDN in long-axis views, in which the PDN runs just infra-medial to the ischial spine, following a straight path approximately 10° ventral to the paramedian long axis of the body. On longitudinal scans, the PDN appeared as a tubular structure with hypoechoic nerve fascicles separated by hyperechoic perineurial connective tissue bands. A 22-gauge needle was carefully inserted on the caudal side, and its tip position was confirmed using small-volume local anaesthetic injections. Once correct placement was verified on the surface of the nerve, an additional dose of local anaesthetic solution (maximum 4 mL in total) was administered, and its spread was observed in real time using long-axis imaging.

Results: In patients with PDN entrapment, especially in severe cases, the boundary between the nerve and surrounding tissue appeared blurred because of the coarsely hyperechoic surrounding tissue. Despite this, PDN was successfully identified in all patients. The injected local anaesthetic solution appeared as a hypoechoic collection, highlighting the nerve surface and confirming successful hydrodissection. Based on a positive response to anaesthetic infiltration, a final diagnosis of PDN entrapment was made in four patients. In four patients, including three without PDN entrapment, the injection completely freed the PDN from the ischial spine and the sacrotuberous ligament. With a one-time injection using this technique, one patient with PDN entrapment experienced long-lasting (> 12 months) relief from perineal pain and pollakiuria (micturition > 20 per day). However, two PDN entrapment patients with a long history of symptoms required open surgical dissection, as repeated hydrodissection (3 and 10 times) failed to achieve complete nerve release from the surrounding tissue.

Conclusions: This case series suggests that long-axis ultrasound imaging can provide valuable insights into the effectiveness of PDN hydrodissection. It allows real-time assessment of the success of the procedure and helps determine whether or when surgical intervention is necessary. Early and timely hydrodissection may improve the treatment outcomes and reduce the need for open surgery.

Introduction: A key point to understand during full endoscopic spinal surgery (FEES) is that a clear operative field, a characteristic of FESS, does not indicate the absence of bleeding because the operative region is continuously irrigated. Effective haemostasis requires specialised techniques and considerations unique to the endoscopic environment.

Technical Note: This study included 177 patients who underwent the FESS. Although the operative fields were appeared bloodless after irrigation. Bleeding could still occur if the direction or pressure of irrigation changed due to scope movement, potentially disrupting the procedure. To ensure smooth progression of FESS, delayed bleeding must be prevented. Small vessels may collapse under irrigation pressure and resemble connective tissue, making accurate identification essential. The primary method of haemostasis involves the bipolar devices, with particular attention paid to maintaining a safe distance from neural structures to avoid thermal injury.

Conclusion: Bleeding and haemostasis during FESS are influenced by specific intraoperative condition. A thorough understanding of these factors is essential for effective surgical outcomes.