Introduction: Cervical spondylotic myelopathy in haemodialysis patients has been reported to have several complications. Destructive spondyloarthropathy is caused by amyloid deposition in the spine, leading to destructive changes and instability. Operations for this condition are challenging because of difficulties in perioperative management. The purpose of this study was to investigate the surgical outcomes of cervical laminoplasty alone and combined with posterior fusion for cervical spondylotic myelopathy in haemodialysis patients.

Methods: Among 23 haemodialysis patients with cervical spondyloarthropathy, 10 underwent laminoplasty alone (Group A) and 13 underwent laminoplasty with posterior fusion using a cervical pedicle screw (CPS) (Group B). The groups were statistically compared regarding C2/7 angle, local kyphosis angle, and clinical outcome (Japanese Orthopaedic Association [JOA] score and recovery rate) at pre-operation (pre) and follow-up (FU). Perioperative complications were also investigated in both groups.

Results: The JOA scores (pre/FU) were 7.9/10.4 points in Group A and 6.9/9.9 points in Group B, with average improvement rates of 35.5% in Group A and 44.3% in Group B. The pre/FU C2/7 angles were 10.9/13° in Group A and −2.6/1.6° in Group B. Local kyphosis was none (pre) in Group A and −14.6/−4.1° in Group B. The perioperative complications included two adjacent lesions and C5 paralysis in two cases; however, no deaths in the perioperative period were observed. These patients needed no revision surgery because they had no neurological symptoms.

Conclusion: In this study, the outcomes of posterior fusion surgeries for destructive spondyloarthropathy were acceptable without any catastrophic complications, even though the patients' preoperative myelopathic conditions were severe.

Haemodialysis (HD) patients have experienced prolongation of lifespan, and the number of these patients with destructive spondyloarthropathy (DS) is increasing. In this study, the outcomes of surgeries for DS were acceptable without any catastrophic complications, even though the patients' preoperative myelopathic conditions were severe. We were able to perform posterior fixation using a CPS with a supporting navigation technique and pedicle marker. The pedicle markers further improved the accuracy of CPS insertion and avoidance of vertebral artery (VA) injury using the navigation system.

Introduction: Anterior transvertebral herniotomy (ATH) is an old unpopular cervical disc herniation technique. We treated 23 patients and demonstrated their surgical indications and clinical results. Furthermore, we introduced surgical tips and tools.

Methods: Twenty-three patients (18 men and five women) underwent ATH. The numeric rating scale was used to evaluate neck and arm pain. Disc height and segment range of motion on plain lateral radiographs were also examined.

Results: All the patients had an intracanal hernia. Because of insufficient tumour removal (n=2) or postsurgical haematoma (n=1), three patients required additional surgery. All patients recovered clinically well. All but one patient maintained segmental disc motion after an average of 26 months of follow-up. Disc height decreases by an average of 0.5 mm/year.

Conclusions: The ATH is theoretically ideal because it preserves motion segments.

However, it has not gained popularity because its surgical indications are unclear and technically demanding. We believe that an intracanal hernia is the best surgical indication. Herniation of the foramen is technically difficult and risks injuring the vertebral artery.

Our study yielded favourable clinical results. Most patients showed preserved segmental motion within the 2-year follow-up period. The disc height loss was 0.5 mm/year, which is very close to natural history.

This article also introduces surgical tips and tools.

Introduction: We investigated the short-term clinical outcomes of 15 patients who underwent double-door cervical laminoplasty using a new titanium plate (CENTERPIECE, Medtronic).

Methods: Fifteen patients (nine men and six women) underwent double-door cervical laminoplasty using a new titanium plate from March 2021. We investigated the operative time, blood loss, intraoperative and postoperative complications, Japan orthopaedic association (JOA) score before surgery and 6 months after surgery, mean C2-7 mid-position angle immediately after surgery and 6 months after surgery, and hinge union on plain computed tomography after 6 months.

Results: The mean duration of the operation was 106 minutes (76-138), and the mean blood loss was 109 cc (30-339). Because the screw failed, one vertebral arch was used as an HA spacer. One case of postoperative C5 paralysis and one of screw backout was observed. The mean C2-7 mid-position angle immediately after surgery was 4.9°, and 6 months later it was 6.3°. The JOA recovery rate was 68.4% 6 months after surgery, and the hinge union rate was 77%.

Conclusion: Despite technical challenges, this surgical procedure is relatively easy and achieves sufficient early stability. Therefore, this innovative technique could be useful for double-door cervical laminoplasty.

Introduction: In Japan, the incidence of pyogenic spondylitis is increasing due to unprecedented population aging and the number of immunocompromised hosts with various complications. We report the effectiveness of minimally invasive surgery using a percutaneous pedicle screw (PPS) and fully endoscopic spine surgery (FESS) for treating spondylitis refractory to conservative treatment at our hospital.

Methods: Of 34 patients treated between April 2017 and March 2021, we retrospectively reviewed 15 consecutive patients who underwent surgical treatment and were followed up for >1 year. The underlying disease, the affected site, the bacteria responsible for the infection, the surgical method, the number of days to surgery, the time to CRP negativity (postoperative), and the length of hospital stay were evaluated. A spinal surgeon completed the radiographic assessments independently.

Results: All 15 patients, 12 men and three women (mean age, 69 years; 36-87 years), underwent minimally invasive spinal surgery. All the patients had underlying diseases, mostly diabetes and cancer. Most affected sites were the L4/5 levels. The bacteria responsible for the infection were identified in 13 (87%) patients. Most bacteria were detected in the blood and only six were detected locally. PPS was performed in nine cases, FESS in two cases, and a combination of PPS and FESS in four cases as the surgical method. The mean duration of days before was 39 days. The average time to CRP negative was 30 days, postoperatively. The average length of the hospital stay was 74 days. In all 15 cases, the infection subsided, and finally, 10 of the 15 cases showed bone fusion at the affected site.

Conclusion: Conservative treatment is the basic treatment for pyogenic spondylitis. However, surgical treatment may be necessary in some cases, if little improvement is observed.

In principle, the surgical treatment at our hospital stabilises the vertebral body affected by PPS. However, FESS is a useful tool that can identify the causative organism necessary for diagnosis and treatment, irrigate with copious amounts of saline, scratch lesions under direct vision, and drain. Good results were obtained by combining these two methods, depending on the case.

Purpose: We investigated risk factors for rod fractures (RFs) in correction surgery using extreme lateral interbody fusion (XLIF), percutaneous pedicle screws (PPSs), and multi-rod constructs for adult spinal deformity (ASD).

Methods: One hundred and two ASD patients underwent correction surgery with XLIF, PPS, and multi-rod constructs between 2018 and 2020 and were followed up for a minimum of 24 months. In all patients, the range of fixation was from the lower thoracic spine to the pelvis. The mean age of patients was 72.1 years, and the mean follow-up period was 54 months. Three rods of 5.5 mm titanium alloy were used in all surgeries. The percentage of RF, the timing of RF, and RF levels were investigated, and various pre- and postoperative parameters were compared between the RF group (RF group) and the group without RF (non-RF group).

Results: Thirteen patients experienced RF. The RF levels were L3/4 in one patient, L4/5 in nine patients, and L5/S1 in three patients. Of the nine patients with RF at L4/5, two patients experienced RF after bone fusion. Of the 13 patients who experienced RF, seven patients experienced anterior longitudinal ligament (ALL) rupture. There were no significant differences in age, gender, rod material, rod diameter, and number of rods between the two groups. Patients in the RF group had significantly larger pre- and post-operative PI, pre- and post-LLIF, post-operative PI-LL, pre- and post-LLIF 2/3 PI-LLL, LLL change with PPS (PPSΔLLL), and postoperative PT. Patients in the RF group had significantly smaller preoperative LLL and preoperative TK. Multivariate analysis included seven independent variables with P<0.01, namely pre- and postoperative PI, postoperative PI-LL, pre- and post-LLIF 2/3 PI-LLL, PPSΔLLL, and ALL rupture. PPSΔLLL and ALL rapture were detected as risk factors for RF, and the cut off value for PPSΔLLL was 8 degrees in the ROC analysis.

Conclusion: PPSΔLLL and ALL rapture were identified as risk factors of RF in circumferential minimally invasive surgery with multi-rod constructs for ASD.

Purpose: We examined the criteria for intervertebral bony release (IBR) with lateral lumbar interbody fusion (LLIF) for intervertebral bony fusion in patients with adult spinal deformity (ASD).

Methods: We included 19 intervertebral levels in 14 patients with ASD and intervertebral bony fusion who underwent correction surgery with LLIF and percutaneous pedicle screw (PPS) fixation between 2016 and 2020. The bony fusion level, bony fusion morphology (anterior/posterior, unilateral/bilateral), and IBR procedures were evaluated. Bony fusion morphology was classified as unilateral or bilateral fusion in the anterior and posterior regions. Furthermore, posterior facet joint fusion was classified as grade 1, where the borders are bridged, and grade 2, where the borders disappear, and the joint is firmly fused. IBR procedures were classified as follows: A, LLIF only; PA, posterior osteotomy (PCO) +LLIF; PA, LLIF+PPS fixation.

Results: The average age was 69.2 years (seven men and seven women), with ten cases of adult idiopathic scoliosis being the most common. In all cases of anterior bone or anteroposterior unilateral fusion, IBR was achieved using LLIF alone in all cases of anterior bony fusion. However, in cases of anteroposterior fusion, IBR was not achieved with anterior or posterior bilateral fusion; in all cases, IBR was achieved with PCO or PPS fixation. One patient with anteroposterior fusion, bilateral posterior fusion, and a grade 2 facet joint did not achieve IBR.

Conclusion: We investigated the criteria for IBR with LLIF alone in patients with ASD and bone fusion. IBR was achieved using LLIF alone for anterior-only fusions. It was recommended that IBR with LLIF alone would be difficult if either the anterior or posterior fusion was bilateral and the facet joint was grade 2.

Introduction: Proximal junctional kyphosis (PJK) and proximal junctional failure (PJF) frequently develop as major complications after surgery for adult spinal deformities (ASD) with long-segment posterior spinal fusion. Despite the various potentially useful techniques reported previously, complications remain difficult to treat. This study adds to our knowledge of the effects of two-level prophylactic balloon-assisted vertebroplasty (BVP) on the incidence of PJK/PJF.

Methods: Twenty-seven patients with adult spinal deformities underwent a combination of lateral lumbar interbody fusion (LLIF), long-segment posterior spinal fusion from the low thoracic spine to the pelvis, and two-level BVP. They were followed up for a minimum 3-year postoperatively. All patients had BVP at the uppermost instrumented vertebra (UIV) and the supra-adjacent vertebra (UIV+1).

Results: Lumbar lordosis (LL), pelvic incidence minus LL (PI-LL), pelvic tilt (PT), the sagittal vertical axis (SVA), and Cobb angle significantly improved after surgery but tended to worsen over time. The cumulative incidences of PJK and PJF after surgery reached 25.9% and 11.1% after 1 year, 40.7% and 18.5% after 2 years, and 48.1% and 22.2% after 3 years.

Five (18.5%) patients required emergency surgery with proximal extension of the fusion for impaired spinal cord function caused by PJF between the UIV and UIV+1 within 2 years after the initial surgery.

Conclusions: Two-level prophylactic BVP did not prevent PJK and PJF but rather carried the risk of acute spinal cord impairment as a trade-off between rigid UIV fixation and increased mechanical stress at the proximal junction.

Introduction: Vertebral plasty is typically performed using calcium phosphate cement in cases where there is persistent pain as a result of non-union osteoporotic vertebral fracture. After surgery, progressive fracturing of the adjacent vertebral body and the advancement of kyphosis due to the correction loss can occur.

Methods: We present a method of encapsulating calcium phosphate paste in the vertebral body without employing cancellous bone curettage and the accompanying surgical results.

Results: There was no difference in terms of pain management or correction loss after vertebroplasty between our proposed method and that involving cancellous bone curettage. No cement leakage into the spinal canal or pulmonary embolism was observed.

Conclusion: Similar results were obtained using the method presented in this study compared with cancellous bone curettage techniques.

Introduction: Comorbidities are common in older adult patients, especially those >90 years of age, and the development of complications and decline in activities of daily living (ADL) are problems in the treatment of osteoporotic vertebral fractures (OVF). Balloon kyphoplasty (BKP) for OVF is a minimally invasive and effective treatment for immediate pain relief and early ADL recovery. We investigated whether BKP is efficacious and safe in older adult patients >90 years.

Methods: The participants were patients aged ≥90 years who were diagnosed with OVF and underwent BKP between January 2018 and November 2021, divided into 20 cases performed within 14 days after injury (very early group) and 15 cases performed after 15 days after injury (standby group). The study items were the numerical rating scale (NRS) for back pain during physical activity before and after surgery, the rate of decline in ADL, and the presence or absence of complications during hospitalisation.

Results: The preoperative and postoperative NRS improved significantly in both groups, with the very early group improving from an average of 6.9 to 3.4 and the standby group improving from 6.5 to 2.5. However, there was no significant difference between the two groups in terms of preoperative and postoperative NRS (see above), ADL decline rate (very early group: standby group = 50%:46.7%), or inpatient complications (10%:6.7%) between the two groups.

Conclusions: BKP for OVF in very older adult patients can be performed without conservative treatment if the pain persists after bed rest and ADL impairment are evident, even if it is not very early.

Introduction: When compared to transforaminal lumbar interbody fusion (TLIF) with a single boomerang cage (DB technique) enhances intervertebral stability. TLIF for lumbar degenerative disease can achieve clinical results comparable to PLIF; however, there are no reports of the superiority of TLIF over PLIF in terms of radiological results, and corrective loss in TLIF is an issue.

Objective: To clarify the intervertebral stability of DB and posterior lumbar interbody fusion (PLIF), including cage subsidence and intervertebral bone fusion.

Methods: The patients underwent DB (group D) or PLIF (group P) for lumbar degenerative disease. The primary outcome was the incidence of cage subsidence (>2 mm on computed tomography) 1 year postoperatively, and the secondary outcome was the incidence of intervertebral non-union. Logistic regression was used to calculate the risk ratio for cage subsidence.

Results: Cage subsidence occurred more frequently in the P group, 15 (17%) cases in the D group, and 26 (41%) cases in the P group (P=0.002); the adjusted risk ratio for cage subsidence in the D group was 0.56 (95% CI: 0.33-0.97), halving the incidence of cage subsidence in the D group compared with the P group. The percentage of non-union between the vertebral bodies was 33 (38%) cases in group D and 29 (45%) in group (P=0.4).

Conclusions: The DB technique may improve intervertebral stability with less cage subsidence than PLIF.

Introduction: Neurofibromatosis type 1 (NF1) causes progressive spinal abnormalities. Perioperative complications are common, including loss of correction and postoperative pseudoarthrosis. Long-term follow-up is frequently required. This report describes two cases of long-term postoperative follow-ups by the same surgeon.

Case Report: Case 1 involved a 66-year-old woman who underwent a combined anteroposterior surgery (Zielke and CD instrumentation) for dystrophic spinal deformity at the age of 35 years. The neurofibroma in the right thoracic cavity increased annually during follow-up; however, the patient did not undergo surgical intervention. Case 2 involved a 60-year-old man with nondystrophic thoracic scoliosis who underwent posterior corrective fixation with a Harrington rod when he was 15 years old. No postoperative pseudoarthrosis or significant loss of correction was observed, and proper sagittal and coronal alignments were maintained. Both patients were satisfied with the surgery's outcome and reported no back pain or other subjective symptoms.

Conclusion: We present two cases of neurofibromatosis type 1 spinal deformity treated using spinal instrumentation, in which the patients were followed up for >30 years. We believe that proper coronal and sagittal alignments contributed to the long-term outcomes.

Introduction: Endovascular treatment for cerebrospinal vascular diseases has recently advanced. Herein, we present two cases of spinal vascular disease successfully treated using endovascular treatment.

Case report: Case 1 involved a cervical spinal dural arteriovenous fistula that caused an intracranial subarachnoid haemorrhage. A liquid embolic agent was used to perform endovascular embolisation of the fistula. During a 5-year follow-up, the patient's spinal dural arteriovenous fistula disappeared with no recurrence. Case 2 involved an extracranial vertebral artery dissection that caused right C5 radiculopathy. A flow-diverter stent was used for endovascular treatment. The C5 radiculopathy improved rapidly.

Conclusion: Endovascular treatment for spinal vascular diseases is efficacious and, in some cases, less invasive than open surgery. Immediate preoperative vascular investigation and surgical planning are essential for successful treatment.

Introduction: We report two cases of Bertolotti's syndrome (Catellvi classification Type IIa) treated using transforaminal lumbar interbody fusion and pseudarthrosis surgery.

Case 1: A 29-year-old woman presented with lower back and leg pains. Her L5 transverse process enlarged and formed a pseudarthrosis with the sacrum. She had decompression for 7 years before being diagnosed with extraforaminal stenosis associated with Bertolotti's syndrome and underwent decompression. She experienced symptomatic relief; however, her lower back and leg pain returned at the age of 25. Imaging revealed no restenosis in the extraforaminal region.

Case 2: A 20-year-old man presented with lower back and leg pains. The transverse process formed a pseudarthrosis with the sacrum. Restenosis was not observed in the extraforaminal region. Both cases were caused by the pseudo-articular area associated with Bertolotti's syndrome. Surgery was performed, and the symptoms subsided.

Conclusion: Bertolotti's syndrome can cause lower back pain and occasionally nerve root symptoms. The patient's symptoms subsided after undergoing transforaminal lumbar interbody fusion.

Introduction: Despite holding soft tissue away from high-speed drills during surgery, tissue can unexpectedly wrap around the drill shaft. We performed experiments to examine what precipitates such mishaps.

Methods: In a windless environment, a Signature Drill System (Stryker) featuring a 4-mm diameter coarse diamond- or cutting bit was placed parallel to a suspended strip of polypropylene. The distance between the end of the strip and the drill shaft or bits was 4- or 8 mm. In another experiment we placed the drill horizontally 10 mm above the top of dry-ice fog. The maximum drill speed was 75,000 rpm and the horizontal motion of the polypropylene strip and the vertical motion of the dry-ice fog were recorded by a video camera.

Results: In the experiments the strip parallel to the vertical shaft and the dry-ice fog were pulled toward the shaft; the higher the revolving drill speed, the faster was its motion. On the other hand, in experiments where the end of the strip was next to either bit, no such motion was observed.

Conclusions: The pulling force generated by revolving high-speed drill shafts may result in tissue wrap-around even when soft tissue is held away from the shaft.