Introduction: Vertebral coplanar alignment (VCA) enables three-dimensional deformity correction using pedicle screw for the treatment of thoracic scoliosis. The purpose of this study was to compare the correction rate between VCA and conventional rod rotation maneuver for adolescent idiopathic scoliosis (AIS) in patients with major thoracic curve.

Methods: Fifty-four AIS patients with Lenke type 1 and 2 (8 males, 46 females, mean age 16.7 years) who underwent posterior corrective fusion with at least 1 year follow-up were enrolled in this study. According to the correction maneuver, the patients were divided into 2 groups: VCA group (21 patients) and conventional group (33 patients). Radiographic parameters and clinical outcomes were compared between the PCI between two groups.

Results: There were no inter-group differences in patient's characteristics, scoliosis type, and operative data. Correction rates of proximal thoracic and main thoracic curve were significantly higher in VCA group in comparison with the conventional group. Thoracic kyphosis formation was also significantly better in the VCA group. On the other hand, no difference was seen in the apical vertebral rotation between two groups. As for clinical outcome, no inter-group differences were observed in Scoliosis Research Rociety-22 revised scores.

Conclusions: VCA could achieve significantly better correction of scoliosis and obtain sufficient thoracic kyphosis than rod rotation maneuver in patients with AIS type 1 and 2. However, the correction of rotation is still insufficient even with this technique.

Background: Lumbar degenerative scoliosis is often accompanied by osteophytes on the concave side of scoliosis. In some cases, the intervertebral spaces and facet joints are fused osseously. It is recommended to break the osseous fusion before cage insertion to correct the scoliosis. We performed dissection of the intervertebral space osseous fusion from the anterior approach alone without posterior osteotomy of osseous fused facet before LIF cage insertion. In the present study, we investigated the local correction angle of intervertebral wedge deformity, endplate injury, and pedicle fracture in LIF cage insertion into intervertebral space with wedge-shaped spontaneous osseous fusion.

Method: The subjects were 4 intervertebral levels in 3 cases with wedge-shaped spontaneous osseous fusion (1 male, 2 females, average 62.6 years old). We approached from the convex side of scoliosis, broke the intervertebral osseous bridge with a chisel, and inserted LIF cage. We investigated the level of fused intervertebral space, intervertebral wedge of preoperative and postoperative, and the local correction angle of intervertebral spaces at coronal image of CT, and the presence or absence of endplate injury and pedicle fracture.

Result: Regarding as intervertebral level, three levels were at L3/4, one level was at L4/5. Local coronal correction angle of intervertebral wedge deformity was −1-9 degrees (the average is 3.7 degrees). One endplate injury and one pedicle fracture occurred in 4 levels.

Conclusion: LIF cage insertion in intervertebral osseous fusion may cause endplate injury and pedicle fracture, but can be corrected with less invasion. LIF at intervertebral space with osseous fusion of intervertebral space and facet joint without posterior osteotomy of osseous fusion is useful for coronal correction.

Introduction: The postoperative period of spinal fusion surgery is marked by stiffness disability. However, little data is available on the details of the mobility of each intervertebral segment. Therefore, we investigated the mobility of each intervertebral segment.

Materials and Methods: Patients with degenerative spine disease who underwent surgery were reviewed. We measured mobile angle on each segment from T11/12 to L5/S1 by preoperative flexion/extension radiographic on sitting position.

Results: One hundred fourteen patients were included in this study. The average age was 65.5 years old. The overall mobility of the T11-S1 was 33.6°. L3/4 had the largest mobility of 6.71°, and the percentage to the total range of motion was 20.0%. T11/12 had the smallest mobility of 1.92°, and the percentage of the total range of motion was 3.4%. The standard deviation was 4.47 for L4/5, the largest variability, and 3.04 for L5/S1, the smallest variability. Dividing the results into lower L4-S1, middle L2-4, and upper T11-L2, L4-S1: 29.2%, L2-4: 39.7%, and T11-L2: 31.1%, with the largest range of motion in L2-4. Paradoxical motion was observed in 67 vertebrae (8.4%), with T11/12 having the highest level of paradoxical motion (27 segments). There was a low negative correlation between the percentage of the range of motion at T11-L2 and age (r = -0.21, p = 0.02).

Conclusion: It was possible to maintain a range of about 30% by reducing the lower fusion end to L4 or the upper fusion end to L2, respectively, in long spinal fusion. The data from this study could be used as an indicator.

Introduction: This study aimed to investigate the accuracy of cervical pedicle screw (CPS) placement with O-arm-based navigation (O-arm NAVI) and the differences between medial and lateral approaches.

Methods: We retrospectively reviewed the records of 67 patients (262 CPSs) who underwent posterior instrumentation of the lower cervical spine with CPS between April 2015 and March 2021 in a single institution. The CPSs were categorized into medial (49 patients, 187 CPSs) and lateral (18 patients, 75 CPSs) approach groups. The intraoperative reinsertion and postoperative perforation rates of the two groups were evaluated and compared.

Results: In 12 patients (17.9%) with 16 CPSs, the intraoperative reinsertions of the CPSs were performed. Of the 16 CPSs, 15 were in the medial approach group. The CPS perforations were detected in 17 patients (25.4%) with 21 CPSs (8.0%). No CPS perforations were observed in the lateral approach group where the average angulation of CPS was significantly higher. Both reinsertion and perforation rates were significantly higher at the C4 CPS.

Conclusion: CPSs insertions can be performed more safely using the lateral approach than the medial approach.

Objective: Lumbar interbody fusion is a standard technique for degenerative lumbar disorders with instability. Minimally invasive technique, extraforaminal lumbar interbody fusion (ELIF) was introduced. Approaching from posterolaterally the posterior muscles and the spinal canal was barely invaded. In spite of theoretical advantage, ELIF was technically demanding and has not been popularized. We developed a micro-endoscopy-assisted Extraforaminal Lumbar Interbody Fusion (mELIF), a technique designed as safe and less invasive interbody fusion. We applied mELIF for L5/S1 disorder in 33 cases and here report clinical results.

Methods: Thirty patients followed over 6 months included, 14 males and 16 females, average age 61.5 underwent the procedure. The index diagnoses were isthmic spondylolisthesis (n=14), foraminal stenosis (n=14), and others. In surgery a patient is put in prone position under general anesthesia. From about 5 cm from midline, as for lateral disc herniation surgery, a 16- or 18-mm diameter tubular retractor was placed at the lateral aspect of the facet joint. The facet joint was partially excised, and the disc space was prepared under micro-endoscopic visual assistance. The spinal canal was not invaded. A cage, local bone and artificial bone graft were inserted into the disc space from unilaterally. Bilateral percutaneous screw-rod constructs were inserted and fixed.

Results: Clinical symptoms greatly improved in most cases. JOA score (full: 29) increased 11.4 to 24.4. NRS improved 6.4 to 2.1 for lumbar and 5.2 to 1.1 for leg. Twenty cases demonstrated excellent and seven good according to Macnab's criteria. The average surgery time was 192 minutes and blood loss 89 mg. There were neither major clinical adverse effects nor additional surgery. Bone union rate was 14 from 20 cases (70%) at one-year post-surgery.

Conclusions: The index diagnosis at L5/S1 were isthmic spondylolisthesis and foraminal stenosis in most cases. The spinal canal is usually not involved in these conditions. ELIF is ideal because it does not need to invade the canal. In addition to theoretical advantage of ELIF, mELIF can provide minimally invasiveness and safety by using microendoscope. We experienced 30 cases and the results were favorable. We are certain that mELIF can be comparable with posterior standard interbody fusion techniques for L5/S1 disorders.

Introduction: Pedicle subtraction osteotomy (PSO), for adult spinal deformity, has been reported to cause a high incidence of rod fracture at the osteotomy site. In our department, the anterior vertebral body replacement is performed on the vertebra with PSO for rod fracture prevention. In this study, we investigated the efficacy of the anterior vertebral body replacement at the vertebra with PSO.

Methods: We retrospectively reviewed 63 patients aged ≥20 years who underwent five or more vertebral fixations with one or more pedicle subtraction osteotomized vertebrae, with a minimum follow-up of 2 years between January 2012 and December 2018 at our hospital.

Results: There were no cases of rod fracture in 45 patients who underwent the anterior vertebral body replacement. Furthermore, rod fracture occurred in 2 of 18 patients who did not undergo the anterior vertebral body replacement.

Conclusions: Anterior vertebral body replacement at the vertebra with PSO may be useful in rod fracture prevention.

Introduction: Lumbar facet syndrome is one of the most common diseases that cause low back pain, but it is not uncommon for it to be accompanied by lower limb pain and numbness. We report our experience of treating a patient with lumbar facet syndrome who presented with lower limb symptoms despite no evidence of lumbar spinal canal stenosis on imaging.

Methods: In this study, eight patients with lumbar facet syndrome who had lower limb symptoms and met the following criteria were included: 1) no evidence of lumbar spinal canal stenosis on MRI or myelography, 2) no evidence of myelopathy, and 3) temporary disappearance of not only back pain but also lower limb pain and numbness after facet joint block.

Results: Four patients were male and four were female. The mean age of the patients was 46 years. The affected vertebrae were L4/5 in 5 cases, L5/S1 in 3 cases, and L3/4/5 in 1 case. Lower limb symptoms were unilateral in 6 cases, bilateral in 3 cases, and extending to the lower leg in 7 cases; one patient had only lower limb pain without back pain. We performed posterior medial branch thermocoagulation in all but one patient who recovered conservatively, and posterior lumbar fusion surgery was performed in 3 patients who relapsed.

Conclusions: In the case of patients with lower limb pain and numbness despite no evidence of stenosis in the lumbar spinal canal or intervertebral foramen on imaging, it is important to confirm the pain relief effect of selective facet joint block and to investigate the possibility of referred pain.

Introduction: Segmental lordosis is an important radiographic parameter as sagittal alignment has been correlated to clinical outcomes. However, there are few reports on the relationship between segmental lordosis angle (SLA) and global spinal alignment (GSA). We retrospectively investigated the relationship between SLA and GSA after TLIF/PLIF.

Methods: The subjects were 106 patients who consecutively underwent mini-open TLIF/PLIF in our hospital between 2016 and 2019 with a minimum one-year follow-up. Subjects consisted of 65 females and 41 males with a mean age of 69.9±11.6 years. Patient factors (age, sex), cage factors (height, lordosis angle, position), radiographic parameters (LL, PI-LL, PT, SVA, TPA), and segmental lordosis angle of the fixed vertebral body (SLA, disc height, intervertebral angle) were investigated. Clinical outcomes were investigated for ODI and JOABPEQ. In addition, the SLA change (ΔSLA) was compared among four groups: Group A: ≤−6°, Group B: −5 to 0°, Group C: 1 to 5°, and Group D: ≥6°.

Results: The overall mean SLA increased significantly from 15.4 degrees before surgery to 17.4 degrees post surgery (P=0.002). SLA, LL, PI-LL, PT, SVA, and TPA also improved significantly after TLIF/PLIF. ΔSLA was 11% in group A, 31% in group B, 28% in group C, and 30% in group D. There were no significant differences in ΔSLA among the four groups with regard to patient background factors, cage factors, GSA, and clinical outcomes. However, there were significant differences in preoperative LL and SLA among the four groups. The lower the preoperative LL and SLA, the more the ΔSLA increased. Postoperative LL was significantly different among the four groups, with an average of 34.6 degrees in group D and an average PI-LL mismatch of 15 degrees, which was inadequate even with the increase in segmental lordosis. Postoperative SVA, TPA, and PT were not significantly different among the four groups, but there was a negative correlation between preoperative SLA and ΔSLA (r=−0.488). There were no significant differences observed in ODI or JOABPEQ among the four groups at the time of the one-year follow-up.

Conclusion: In patients with low preoperative LL and SLA, postoperative SLA increased, but inadequate segmental lordosis and PI-LL mismatch remained. Although ΔSLA had no effect on GSA and clinical outcomes, patients with preoperative PI-LL mismatch may need to be more aware of the development of segmental lordosis in long-term outcomes.

Case 1: A 79-year-old man underwent circumferential corrective fusion surgery from T7 to pelvis including L4 vertebral body reconstruction and L1-3 XLIF for kyphotic deformity after L4 osteoporotic vertebral collapse. Nine months after the surgery, the screw neck fracture of right S2 alar iliac (S2AI) screw was found. The broken S2AI screw could not be removed, and the pelvis was fused with two iliac screws, one on each side.

Case 2: A 72-year-old woman underwent posterior corrective fusion surgery from T6 to pelvis for kyphotic deformity after T12 osteoporotic vertebral collapse. Two months after the surgery, the broken screw neck of the bilateral S2AI screws were found. In this case, the broken screws could be removed, and the S2AI screws were reinserted bilaterally and reinforced with an additional SAI screw on the right side only.

Case 3: A 77-year-old man underwent posterior corrective fusion surgery from T8 to pelvis with L4 PSO for failed back surgery syndrome. A year and a half after surgery, bilateral set screw dislodgement of the S2AI screws were found. The pelvis was fused by reinserting the same size S2AI screws and adding bilateral S1 screws.

Conclusion: In spinal implants, stress concentration continues to occur at the most vulnerable part of the construct until bone fusion is achieved. It is important to recognize that even a strong S2AI screw can break.