Introduction: CMEL (Cervical MicroEndoscopic Laminotomy) using a spinal endoscope has been reported as a surgical treatment for cervical myelopathy. In our department, we have introduced a modified version (CMEL) of laminectomy. This technique is minimally invasive, but the selective decompression and discectomy may worsen the outcome compared with conventional treatment.

Objective: To compare the 1-year results of the CMEL variant and the Kurokawa method in our department, and to clarify the usefulness and problems of the CMEL variant.

Methods: The CMEL variant is a method of complete resection of the lamina between the open intervertebral space. The subjects were 31 cases of CMEL variant and 39 cases of Kurokawa method. The study items were operative time, blood loss, complications, postoperative hospital stay, JOA score before and 1 year after surgery, JOACMEQ, and neck pain NRS.

Results: There was no difference in mean operative time. Mean blood loss was lower in the CMEL variant. There was no difference in JOA score before and after surgery, and no difference in JOACMEQ except for cervical spine function before surgery. There was no difference in neck pain NRS both preoperatively and postoperatively.

Conclusions: The CMEL variant is an excellent technique with postoperative results comparable to those of the Kurokawa method, and also allows early discharge from the hospital due to its minimally invasive nature.

Introduction: We employed minimally invasive surgery (MIS), as an alternative to direct posterior decompression with instrumented fusion, for patients who had neurologic symptoms associated with osteoporotic lumbar vertebral fractures. This study assessed the CT- and MRI-evidence of indirect neural decompression achieved by an MIS strategy consisting of transpsoas lateral lumbar interbody fusion (LLIF), Balloon kyphoplasty (BKP), and percutaneous pedicle screw (PPS) -Rod fixation.

Methods: Four patients, who had neurologic symptoms associated with unhealed osteoporotic vertebral fracture of L4, underwent a single-stage MIS and had a minimum 2-year follow-up. The MIS consisted of three surgical techniques performed in the following order: (1) the BKP for the L4 fractured vertebral body in the prone position; (2) the LLIF for the adjacent intervertebral levels of the L3-L4 and L4-L5 in the lateral position; and (3) the PPS-Rod fixation at L3 through L5 in the prone position. We evaluated the indirect neural decompression at the LLIF levels with CT and MRI scans, and clinical results with the JOA score.

Results: As compared to preoperative values, the postoperative CT measurements at the LLIF levels revealed significant increases in disc height at the anterior (12.2±0.6 mm to 15.4±0.5 mm), middle (11.8±0.8 mm to 14.7±0.6 mm) and posterior edges (6.0±0.8 mm to 8.7±0.7 mm), and in bilateral foraminal height (13.8±0.9 mm to 18.3±0.6 mm on the left; 14.1±0.5 mm to 17.6±0.4 mm on the right). CT scans at 2-year follow-up continued to show significant increases of the values.

Also at the LLIF levels, axial T2-weighted MRIs demonstrated a significant progressive increase from the preoperative values to those 1-year and 2-year postoperatively in cross-section area of the dural sac (77.4±9.8 mm² to 146.2±15.1 mm² and 170.4±14.6 mm²). The corresponding T1-weighted MRIs showed significant progressive decreases of the ligamentum flavum in cross-sectional area (101.3±7.8 mm² to 70.2±5.5 mm² and 54.4±3.7 mm²) and thickness (4.1±0.2 mm to 2.9±0.3 mm and 2.3±0.3 mm on the left; 4.4±0.3 mm to 3.2±0.2 mm and 2.5±0.3 mm on the right). Two-year postoperative CT scans confirmed a solid interbody fusion at all 8 LLIF levels, and the JOA score significantly improved from 9 points preoperatively to 22.5 points postoperatively.

Conclusions: A combination of BKP, LLIF and PPS, if performed in this order, serves as an excellent MIS strategy for neurologic compromise associated with unhealed osteoporotic fracture of the lumbar spine, affording indirect neural decompression and spinal stabilization.

Introduction: Trans-Kambin's Triangle Lumbar Interbody Fusion (KLIF) is a technique that involves a cage insertion through Kambin's safety triangle to preserve the posterior elements without exposing the dura. We have developed a full-endoscopic lumbar interbody fusion technique by combining KLIF with Biportal Endoscopic Spine Surgery (BESS), which is an endoscopic spine surgery that uses two portals. In this study, we evaluated the results in patients treated with this technique at 1 year postoperatively.

Methods: Eighteen patients (8 males and 10 females, mean age 68 years) who underwent single-lumbar interbody fusion using this technique were included in the study. The preoperative diagnosis was spondylolisthesis in 13 cases, canal stenosis in 3, recurrent herniation in 1, and foraminal stenosis in 1. The improvement rates of back pain and lower extremity pain and numbness, recovery rate of JOA score, and fusion rate at 1 year postoperatively were evaluated.

Results: At 1 year postoperatively, the improvement rates of back pain, lower extremity pain, and lower extremity numbness were 56%, 73%, and 65%, respectively, and the JOA score recovery rate was 78%. At 1 year postoperatively, 61% (11/18) patients showed fusion on CT imaging.

Discussions: The BE-KLIF technique is a minimally invasive interbody fusion technique that allows bilateral insertion of two 12-mm wide cages and four screws with only four 2-cm incisions. The expandable cages are inserted through Kambin's safety triangle to achieve indirect decompression without exposing the dura. In these cases, the postoperative results were stable, suggesting that indirect decompression with posterior invasion can also improve neurological symptoms.

Conclusions: BE-KLIF is a useful, minimally invasive, full-endoscopic lumbar interbody fusion technique.

Introduction: In lumbar isthmic spondylolisthesis, radiculopathy caused by foraminal stenosis are common, but cauda equina symptoms are not a few. In some lumbar isthmic spondylolisthesis patients with cauda equina symptoms, spinal canal stenosis is not serious comparing to degenerative lumbar spinal canal stenosis. In this study, we evaluated the shapes of spinal canal stenosis in lumbar isthmic spondylolisthesis patients by functional imaging of CT myelography.

Methods: In this study, excluding patients who could not be measured because contrast was not depicted due to serious stenosis, 9 patients were included with lumbar isthmic spondylolisthesis who underwent functional imaging of CT myelography at our hospital from July 2017 to May 2021. Anteroposterior diameter, transverse diameter, and cross-sectional area of dural sac were measured in each position with flexion and extension of functional imaging of CT myelography for each case. In addition, the decreasing ratio in the anteroposterior and transverse diameter was calculated. The slices used for the measurements were reconstructed to be parallel to the inferior endplate of slipped vertebra. The height was set at the pars cleft level. For statistical analysis, we conducted a paired t-test. Statistical significance was set at P < 0.05.

Results: The mean anteroposterior diameter was 13.4 mm during flexion and 11.4 mm during extension (P = 0.049). The mean transverse diameter was 14.0 mm during flexion and 11.9 mm during extension (P < 0.001). The mean cross-sectional area was 168.6 mm² during flexion and 126.7 mm² during extension (P < 0.01). The decreasing ratio in the transverse diameter was greater than the ratio in the anteroposterior diameter in 5 cases.

Conclusions: All cases showed a decrease in the cross-sectional area of dural sac during extension. In degenerative lumbar spinal canal stenosis, the anteroposterior diameter of dural sac often decreased due to yellow ligament thickening and disc protrusion. On the other hand, in 5 cases of lumber isthmic spondylolisthesis, there was compression from both sides due to the ragged edge, which reduced the transverse diameter more than the anteroposterior diameter. MRI slice was created at only vertebral disc level and not at the pars cleft level. Furthermore, if the anteroposterior diameter does not decrease in the sagittal image, it may not be recognized that the transverse diameter decreases, so the spinal canal stenosis may be underdiagnosed. Therefore, careful attention should be paid to the imaging evaluation of lumbar isthmic spondylolisthesis.

Introduction: Osteoporotic vertebral body fractures with spinal canal stenosis are often associated with osteoporosis, spinal deformity, and intervertebral instability, and are often difficult to treat. We report the clinical results of using Balloon kyphoplasty (BKP) and microendoscopic laminotomy (MEL) for lumbar vertebral body fractures with spinal canal stenosis.

Methods: The subjects were 7 patients (2 males and 5 females, average 85 years old) who underwent surgical treatment at our department and related hospitals. Fracture sites are L1: 1 case, L3: 1 case, L4: 2 cases, L5: 3 cases, and decompression sites are L1/2: 1 case, L3/4 and L4/5: 3 cases, L4/5: 2 cases, L3 lumbar foraminal: 1 case. The average postoperative follow-up period was 13±6.0 months (6 to 21 months). The examination items were operation time, blood loss, Numerical rating scale (NRS) for back pain/leg pain (preoperative, postoperative, at final follow-up), and JOA score, changes in ADL before surgery and at final follow-up. As an X-ray evaluation, the anterior/posterior height of the fractured vertebral body, wedged angle of the vertebral body, and local kyphosis angle were measured before surgery, immediately after surgery, and at the final follow-up, and the presence or absence of bone union and perioperative complications were also evaluated.

Results: The average operation time was 144±61minutes and the average blood loss was 46±53 ml. NRS for back pain and leg pain were 8.7±2.2 and 6.7±2.0 before surgery, 2.3±0.8 and 3.4±1.5 immediately after surgery, and 1.1±1.1 and 1.3±1.7 at the final follow-up. Anterior height of fractured vertebral body, posterior height of that, vertebral body wedge angle, and local kyphosis angle were 15.8±5.4 mm, 26.0±2.3 mm, 14.1±8.2 ° and −1.7±21.2 ° before surgery, 22.5±3.3 mm, 26.8±3.0 mm, 6.7±5.7 °, and −5.6±22.9° after surgery, respectively. At the final follow-up, it was 20.6±3.1 mm, 27.3±1.9 mm, 9.2±5.8 °, and −2.3±20.1 °. All patients had bone union in average 6.7 months and there were no perioperative complications.

Conclusions: The combined surgery of BKP and MEL was minimally invasive and preserved the posterior tissue of lumbar spine, and no postoperative local kyphosis progress was observed. It may be considered as one of the treatment options especially for elderly patients with medical complications.

Introduction: Since thoracolumbar vertebral fracture with diffuse idiopathic skeletal hyperostosis (DISH) is common in the elderly, it may occur with low-energy trauma based on osteoporosis. Conservative treatment such as bed rest and brace may cause nonunion and delayed paralysis due to the long lever arms of the fractured segments that make the fracture extremely unstable, long fusion surgery using instrumentation is often performed. On the other hand, Balloon kyphoplasty (BKP) is indicated for primary osteoporotic vertebral fracture that cannot be treated with conservative treatment. The purpose of this study was to investigate the effectiveness of treatment with BKP for the osteoporotic thoracolumbar vertebral fracture with DISH.

Methods: 16 patients (7 males and 9 females, average 84.1 years old, range 71-94) with thoracolumbar fracture with DISH were treated with BKP. The periods from injury to first visit were average 20.1±26.7 days (range 0-80). Follow-up periods was 17±9.5months (range 3-36). The numbers of DISH affected vertebral body were average 9.0 (5-17). Outcome measurements were Numerical Rating Scale (NRS) for back pain, and use period of teriparatide and brace. Radiographic measurements were fracture type, existence of bone union, existence of postoperative subsequent fracture, local kyphosis angle and wedged angle of the vertebral body.

Results: All patients had bone union at average 6.4 months after BKP. All patients were wearing hard braces for average 4.1months with using teriparatide for average 8.6 months after BKP. Fracture types were wedged compression type (14 patients) and insufficient fracture (2 patients), there was no dislocation, the posterior ligament injury and facet joint injury in all patients. NRS was 8.6±1.2 before BKP, 0.8±1.1 after BKP and 1.7±2.1 at final follow-up. Local kyphosis angle was 20.1±9.1° before BKP, 10.2±5.4° after BKP and 18.1±9.6°at final follow-up. Wedged angle of the vertebral body was 15.5±5.3° before BKP, 6.4±4.6° after BKP and 10.9±4.2°at final follow-up. Postoperative subsequent fractures occurred in 4 patients, but they were healed with conservative treatment.

Conclusions: 1. BKP for thoracolumbar vertebral fracture with DISH is indicated to fracture of the anterior column without dislocation, the posterior ligaments injury and facet joints injury. 2. BKP for thoracolumbar vertebral fracture with DISH is minimum invasive surgery and more effective method by adding teriparatide and rigid hard brace.

Introduction: There is a learning curve in spinal endoscopy, which is a major obstacle in learning spinal endoscopy. In this article, we present the learning curve of cases performed without direct supervision after 5 months of short-term training at a spine endoscopy training facility, divided into endoscopic discectomy (MED) and endoscopic laminectomy (MEL), and present the experience of a single surgeon initiating spinal endoscopic surgery.

Subjects and Methods: The subject was orthopedic surgeon who had been licensed as a physician for 10 years and an orthopedic surgeon for 4 years. After performing spinal surgery (non-endoscopic surgery) in about 130 cases, he conducted a short-term training, he observed about 90 cases of spinal endoscopic surgery, and experienced 19 cases. Fifty-two spine endoscopic surgeries (MED 15 cases, MEL 37 cases) performed during the 9-month period immediately following the end of training were included in the study, and operative time, blood loss, JOA score improvement rate, and complications were examined.

Results: The mean operative time for MED was 62 minutes, the mean blood loss was 11.3 ml, and the mean JOA score improvement rate was 77.1%. There was no learning curve and no complications. The mean operative time for MEL was 69 minutes, the mean blood loss was 9.3 ml, and the mean JOA score improvement rate was 66.9%. The operative time showed a learning curve in the initial 14 cases, and we experienced complications of dural injury in the 18th case and a wrong-site surgery in the 35th case.

Conclusion: The learning curve of single-operator spinal endoscopic surgery performed after short-term training in spinal endoscopy is presented. Short-term training contributed to good surgical outcomes and avoidance or shortening of the learning curve.

Introduction: It is well known that to learn the skill of full-endoscopic spine surgery (FESS) has steep learning curve. In this study I discussed the learning curve of the surgeon who introduced FESS. The author started FESS under the guidance of the certificated surgeon.

Methods: From April 2017 to March 2021, the author performed FESS to 200 cases. Of those cases, I picked out 50 cases that we performed interlaminar approach without using bone reamer and 63 cases that we performed transforaminal or posterolateral approach without using bone reamer. I analyzed the learning curve and perioperative events. In addition those, I compared the learning curves of early period (E) that I performed it more often and late period (L) that I did less often.

Results: The mean operation time was 51.2 minutes in IL and 45.2 minutes in TF/PL. The learning curve was shown with a down trend in both approaches. Comparing E period and L period, the learning curve in L showed upward trend. The less I experienced the number of patients, the more I wasted the time. I had 6 troubles in approach and 2 cases at making decision to sufficient decompression. Post operatively, I had 2 cases that worsened their leg pain and a patient that had early reoperation.

Conclusion: Even if surgeons have no experiences of MED, they can learn the skill of FESS under the guidance of the certificated surgeon. It seems more familiar with starting TF/PL approach.

Introduction: We performed a modified approach to the L1/2 disc from the 10th intercostal space for lateral interbody fusion (LIF) cage insertion with multiple-segmental fusions. This approach does not require the resection of the 11th rib and dissection of the diaphragm. Here, we report the postoperative results of this approach.

Methods: First, we exposed the L2/3 disc via the retroperitoneal approach and manually detached the diaphragm from the 11th rib retrogradely. Next, we made another skin incision at the 10th intercostal space and cut the intercostal muscles. Finally, we inserted a retractor dedicated to LIF and approached the L1/2 disc.

We performed this modified approach on 10 cases, 4 males and 6 females. Their average age was 71.1 years. The fusion levels were 3 intervertebral segments in 2 cases, 4 intervertebral segments in 7 cases, and 2 intervertebral segments with vertebral body replacement in 1 case. Posterior fusion of the vertebrae was performed in all cases after this LIF insertion. We investigated the following complications: pleural injury, endplate injury, anterior longitudinal ligament injury, and abdominal flank bulge.

Results: Pleural injuries occurred in 2 cases. No pneumothorax appeared postoperatively in those cases. No endplate injury, anterior longitudinal ligament injury, or abdominal flank bulge occurred.

Conclusions: Resection of the 11th rib and dissection of diaphragm are usually performed in LIF of the L1/2 level. However, the diaphragm is very thin in the elderly which makes it difficult to suture the diaphragm after dissecting. Moreover, diaphragmatic dysfunction in the elderly can cause postoperative respiratory disorders. We considered this approach useful because it protected the diaphragm. Our modified approach avoids the dissection of the diaphragm and preserves the intercostal nerves; thus, may prevent postoperative respiratory disorders compared to the conventional approach. Therefore, this approach with 2 skin incisions is useful for inserting the LIF cage into the L1/2 level.

Introduction: Many surgeons introduce full endoscopic discectomy (FED) after having experienced LOVE and MED methods. In this study, we examined the learning curve of FED for a surgeon who had no experience with either method.

Methods: The subjects were 90 cases of lumbar disc herniation who underwent FED in one level. The study period was from October 2019 to August 2021. The surgeon had no experience with LOVE or MED methods. Operation time, complications, and JOA score were investigated.

Results: Fifty-two patients (36 males, 16 females) were treated by IL procedure with a mean age of 48.4 years, and 38 patients (26 males, 12 females) were treated by TF procedure with a mean age of 53.1 years. The mean operation time was 80.2 min for IL and 78.7 min for TF. The operation time for both methods decreased with the increase in the number of cases (IL: R=-0.4, p< 0.05, TF: R=-0.4, p< 0. 05). Complications included postoperative muscle weakness in 1 case and nerve root injury in 1 case, for a total of 2 cases (3.8%) in IL, and nerve root injury in 2 cases (7.1%) in TF. Recurrence was observed in 7 cases (13.5%) by IL and 3 cases (7.9%) by TF. The improvement rate of JOA score was 88.2% in IL and 84.1% in TF.

Conclusion: The surgeon who had no experience with LOVE or MED methods may be able to perform FED under the environment of various training and sufficient guidance.