S1 pedicle screw and sacral alar screw are used as the standard sacral anchor for fixation to treat various spinal disorders and pelvic trauma. Bicortical fixation, wherein the screws penetrate the anterior sacral cortex, is often used to achieve greater stability than that with monocortical fixation. However, screws penetrating the anterior sacral cortex have a risk of neurovascular injury, and we have experienced two cases of postoperative L5 nerve root injury caused by anterolateral malpositioning of the S1 pedicle screws. Therefore, we investigated the anatomy of the L5 nerve root in the pelvis to clarify a safety zone for sacral screw placement. All of the L5 nerve roots coursed outward after exiting the intervertebral foramina. L5 nerve roots tended to take an outward course after changing their angle at the most anterior surface of the ala of the sacrum. L5 nerve roots were positioned close to the ala of the sacrum and had poor mobility. These findings suggest that surgeons should insert the S1 pedicle screw medially toward the inside of the S1 anterior foramina, and the sacral alar screw laterally with an angle >30° to prevent iatrogenic L5 nerve root injury.

Introduction: Osteoporotic vertebral fractures may progress and eventually result in a significant reduction in the quality of life of affected patients owing to residual pain and neurological deficits. Although vertebroplasty has been a widely accepted treatment option, it has been occasionally followed by an adjacent vertebral fracture (AVF). This eventually results in inadequate pain relief. Since there was no consensus on the causal relationship between vertebroplasty and AVF, we examined this association.

Methods: We included consecutive patients who underwent vertebroplasty of a single vertebral body between April 2012 and June 2018 at 1 of 6 hospitals and followed them up for 6 months. We evaluated the incidence of AVF within 1 week, 1 month, 3 months, and 6 months postoperatively and determined the 95% confidence intervals (CIs). The Kaplan-Meier method was used to illustrate the cumulative incidence of AVF, censoring at 6 months after vertebroplasty.

Results: A total of 505 patients were included in this study, all of whom underwent balloon kyphoplasty. A total of 406 patients were included in the analysis after the exclusion of 99 patients who did not meet the inclusion criteria. Seventy-four AVFs were observed for up to 6 months postoperatively, with AVFs occurring within 1 week in 29 of 405 (7.2% [95% CI 4.8-10]), 1 month in 58 of 377 (15% [95% CI 12-19]), 3 months in 71 of 353 (20% [95% CI 16-25]), and 6 months in 74 of 317 (23% [95% CI 19-28]) patients. The median time to onset of the postoperative AVF was 16 days (interquartile range 6-35), with the time to onset of up to 1 week for 29 of 74 (39%) cases and up to 1 month for 58 of 74 (78%) cases. The cumulative incidence curve showed a steep rise in the early postoperative period.

Conclusions: The results of this study suggest that there is an association between vertebroplasty and AVF. These results may motivate further research on the prediction of the incidence, impact, prevention, and treatment of postoperative AVF.

Introduction: Lumbar spondylolysis is a frequent fatigue fracture in adolescent athletes. The fourth lumbar vertebra (L4) spondylolysis is less frequent than the fifth lumbar vertebra (L5).

Methods: A total of 41 cases with 59 lesions (excluding pseudarthrosis lesions) diagnosed as L4 spondylolysis over 6 years from 2014 were included in this study. Conservative treatment included semi-hard brace and exercise prohibition and athletic rehabilitation were performed in all cases. We investigated age, sex, discipline of sport, unilateral/bilateral cases, and pathological stage of Computed Tomography (CT) axial slice at initial examination. After Magnetic Resonance Imaging (MRI) signal change disappeared, CT was performed to evaluate for bony union or pseudoarthrosis. The relationship between each factor and the bony union was analyzed using Fisher exact tests. Significance was set at p < 0.05.

Results: The mean age of the patients was 14.5 years, 31 were boys and 10 were girls, and the most common discipline was soccer, followed by baseball. There were 21 unilateral cases and 20 bilateral cases. Eighteen of the bilateral cases were bilateral fresh cases and two cases were unilateral fresh with contralateral pseudarthrosis cases. The union rate after conservative treatment was 81%, and the average treatment period was 105 days. The distribution of pathological stage was pre-lysis:early-stage:progressive stage = 15:30:14. The union rate of pre-lysis and early-stage was 89% and the union rate of the progressive stage was 57%. There was a significantly lower union rate in the progressive stage than pre-lysis and early-stage (p = 0.015). Additionally, the union rate of unilateral cases was 95% and that of bilateral cases was 70%. There was a significantly lower union rate in bilateral cases than unilateral cases (p = 0.045). The union rate of bilateral fresh cases was 78% and that of unilateral fresh with contralateral pseudoarthrosis cases was 0%. There was a relatively lower union rate in unilateral fresh with contralateral pseudoarthrosis cases than bilateral fresh cases (p = 0.078).

Conclusions: The union rate in the conservative treatment of L4 spondylolysis is 81%; however, the union rate of progressive stage lesions was significantly lower. Furthermore, the union rate of bilateral cases was significantly lower and that of unilateral fresh with contralateral pseudoarthrosis cases was relatively lower.

Introduction: The pathophysiology of lumbar degenerative spondylolisthesis (LDS) is still unclear. LDS often occurs in middle-aged and older people, but few reports compare the features of LDS by age. This study compared age-specific differences in intervertebral components, such as facet joints and intervertebral discs.

Methods: Patients with LDS who underwent surgery from the 50s to the 80s were randomly selected. Each group had 30 cases (15 males and 15 females), totaling 120 cases. The measurement was carried out using plain X-ray and computed tomography scan. This study investigated facet joint angle, the tropism of the facet joint, sex difference, and the degree of degeneration of the facet joints and intervertebral disc.

Results: The facet joint angle grew gradually shallow with age. There was no significant correlation between the tropism of the facet joint and sex deference. Degeneration of the facet joints was severe throughout all ages. The degeneration of the intervertebral disc was higher in the elderly.

Conclusions: Age-related changes in the spine are said to begin at the intervertebral disc. As a result of degeneration of the intervertebral disc, vertebral body slip may occur when the facet joint and posterior supporting tissue of the vertebra cannot support the vertebral body.

Introduction: Intraoperative triggered electromyography (tEMG) is used during instrumentation surgery for early detection of screw malposition. The association between tEMG findings through lumbar pedicle screw stimulation and neurological deficits, however, remains unknown. The purpose of this study is to assess whether a low threshold tEMG response to lumbar pedicle screw stimulation can serve as a predictive tool for neurological deficit.

Methods: Between February 2018 and April 2020, we measured both tEMG and transcranial electrical motor-evoked potential in 56 patients (294 screws). We utilized probe or screw stimulation, and tEMG was recorded from the lower extremity muscles. A stimulation threshold of <10 mA was considered to be positive. Perforation or malposition of screw or probe was evaluated in postoperative computed tomography (CT).

Results: The tEMG positive alert was detected in six screws (six patients), in whom screw insertion route was changed during operation. A trace of perforation by PS or probe was observed in postoperative CT in all six cases.

Conclusions: The tEMG could detect perforation of pedicle screw accurately. When tEMG was detected, a change in the screw insertion route is strongly recommended.

Introduction: Retrospective review was performed to investigate the radiological change and growing following occipitocervical (OC) or C1-C2 fusion in pediatric patients with Down syndrome.

Methods: In total, seven patients underwent OC or C1-2 fusion. Their O-2 angle, C1-2 angle, C2-7 angle, vertebral body height, vertebral body diameter, intervertebral disc height, and canal diameter of each vertebra were evaluated at preoperation, 1, 2, 3, and 5 years postoperation.

Results: Vertebral body height, vertebral body diameter, and intervertebral disc height (C6/7) were significantly increased at 5 years compared with the preoperative state although canal diameter did not change significantly.

Conclusions: C2 vertebra increased through the caudal side because the epiphyseal ossification center remained. The spinal canal diameter in the cervical spine has been expanded until 5-7 years.

Introduction: The purpose of this study was to analyze the factors associated with low back pain (LBP) in patients with lumbar spinal stenosis (LSS).

Methods: In total, 120 patients with LSS (52 males and 68 females; mean age, 64.1±1.8 years) participated in this study. LBP was defined as pain on the posterior aspect of the trunk between the 12th rib and the lower end of the glenoid groove that lasts for > 3 months. The patients were classified into two groups: high (H) group, which had a LBP visual analog scale (VAS) score > 30 mm, and the low (L) group, which had a LBP VAS score ≤30 mm. The age, gender, body mass index, neurological disorder pattern, bone mineral density, slippage, spinopelvic alignment, disc degeneration, cross sectional area and fatty infiltration of the multifidus muscle, Modic changes, and facet degeneration were compared between the H and L groups. Multiple logistic regression analysis was performed with group H and L as dependent variables.

Results: In the H and L groups, the mean lower leg pain VAS was 73.3±4.6 mm and 50.3±3.5 mm (p< 0.01), the mean lower leg numbness VAS was 76.2±4.9 mm and 51.2±4.1 mm (p< 0.01), the mean lumbar lordosis (LL) was 32.6±3.0° and 40.4±3.1° (p< 0.01), the mean sagittal vertical axis (SVA) was 54.4±6.6 mm and 29.2±6.2 mm (p< 0.01), the mean sacral slope was 27.7°±1.3° and 32.3°±1.4° (p< 0.05), and the mean pelvic incidence (PI) -LL was 15.9°±0.8° and 9.6°±0.7° (p< 0.01), respectively. A multiple logistic regression analysis showed that SVA (OR, 1.017; 95% CI: 1.003-1.031, p < 0.05) and PI-LL (OR, 1.058; 95% CI: 1.012-1.152, p < 0.05) were significantly associated with LBP.

Conclusions: SVA and PI-LL were considered to be associated with LBP in patients with LSS.

Introduction: The analgesic effect and safety of multimodal cocktail injection after cervical laminoplasty were examined in a prospective randomized controlled trial.

Methods: A total of 50 patients, who underwent cervical laminoplasty, were randomized into two groups. The cocktail group (25 patients) received intraoperative wound infiltration of local anesthetics, epinephrine, prednisolone, and nonsteroidal anti-inflammatory drugs at the end of surgery. The noncocktail group (25 patients) received only intraoperative wound infiltration of levobupivacaine. The outcome measures were amount of postoperative analgesic usage within 24 hours and visual analogue scale (VAS) for pain within 7 days and time to first analgesic demand.

Results: Wound pain VAS was low in the cocktail group at all measurement points 6 hours after surgery, and significantly lower in the cocktail group 1, 3, 5, and 6 days after surgery (p = 0.01, 0.019, 0.024, 0.009). The total amount of postoperative analgesic usage in the first 24 hours was significantly lower in the cocktail group (p = 0.04). No complications, such as postoperative muscle paralysis or wound infection, were observed.

Conclusions: Multimodal cocktail injection significantly reduced VAS for wound pain within 6 days and analgesic usage within 24 hours in postoperative analgesia with no increased side effects after cervical laminoplasty.

Introduction: Although extension injuries are rare in traumatic thoracic and lumbar spine injuries and most of them are not accompanied by vascular injuries, severe complications such as vascular, esophageal, and ureteral injuries from extension injuries have been reported in diffuse idiopathic skeletal hyperostosis (DISH). Here, we investigated fracture-related risk factors for severe complications in thoracic and lumbar spine injuries.

Methods: Thoracic and lumbar spine injuries of the 210 vertebrae in 176 patients with AO-A3, 4, B, C, who underwent surgical treatment, were included. Severe complications were defined as injuries of the vessels or organs in the surrounding tissues of the fractured spine such as esophagus, thoracic duct, diaphragm, aorta, segmental artery, and ureter, and we divided all objects into the following two groups: group S (severe complication) and group N (no complication).

Results: There were 14 vertebrae of 14 cases in group S and 196 vertebrae of 162 cases in group N. Severe complications were segmental artery injury, thoracic duct injury, esophageal injury, ureteral injury, diaphragmatic hernia, and shifting embolization of aortic plaque. There were significant differences in age, AO classification, extension injury, and DISH between group S and N. Multiple logistic analyses using these factors as variables showed that extension injury was a risk factor for severe complications. There was also a significant difference in death within 1 month after surgery between both groups.

Conclusions: Extension injury in thoracic and lumbar spine was a high-risk factor of severe complications. Even in low-energy trauma, DISH spine extension injury was also a high risk of severe complications and should be notable.

Introduction: The size of lumbar disc herniation and its spinal canal occupancy has been reported to be related to back pain, leg pain, and numbness. It has also been reported that obesity can affect the clinical symptoms of lumbar disc herniation. We evaluated the relationship between the preoperative clinical symptoms and size of the hernia, its spinal canal occupancy, and body mass index (BMI) in patients with lumbar disc herniation.

Methods: We evaluated the relationship between the size of the hernia, its spinal canal occupancy on preoperative magnetic resonance imaging (MRI) and BMI, and clinical findings using visual analogue scale (VAS) of lower back pain, lower extremity pain, and numbness and Japanese Orthopaedic Association Back Pain Evaluation Questionnaire (JOABPEQ) in 101 patients with lumbar disc herniation who underwent surgical treatment at our hospital. In addition, the VAS was divided into the severe and mild-moderate pain and numbness groups, and the JOABPEQ items were divided into the severe and mild-moderate disability groups for comparison regarding age, sex ratio, BMI, size of hernia, and its spinal occupancy.

Results: Logistic regression analysis revealed that being female was a factor for severe leg pain and high BMI was a factor for severe back pain and gait disturbance in the L4/5 group.

Conclusions: It was concluded that sex was associated with lower extremity pain, while BMI was associated with lower back pain and gait dysfunction in the L4/5 level.

Introduction: Supervised physical therapy (PT) for patients with lumbar spinal stenosis (LSS) leads to better short-term outcomes than unsupervised exercise; however, it is unclear whether short-term effects persist and whether patients with LSS who receive supervised PT are less likely to undergo surgery than those performing unsupervised exercise. This study aimed to compare the one-year outcomes of patients with LSS treated with supervised PT or unsupervised home exercise (HE).

Methods: Forty-three patients were randomly allocated to the PT group, which performed supervised PT twice a week for six weeks, while forty-three patients were allocated to the HE group. PT included manual therapy, individually tailored stretching and strengthening exercises, cycling, and body weight-supported treadmill walking. All patients in both groups were prescribed the HE program comprising lumbar flexion and strengthening exercises and walking. The primary outcome was symptom severity on the Zurich Claudication Questionnaire (ZCQ) at 1 year. The surgery rate after 1 year was compared between groups.

Results: At 1 year, more patients in the PT group than in the HE group achieved minimum clinically important differences in ZCQ symptom severity (60.5% vs. 32.6%; adjusted odds ratio [AOR] 4.3, [95% confidence interval {1.5-12.3}], P =.01); ZCQ physical function (55.8% vs. 32.6%; AOR 3.0 [1.1-8.1], P =.03); Japanese Orthopaedic Association Back Pain Evaluation Questionnaire lumbar spine dysfunction (40.0% vs. 13.2%; AOR 4.8 [1.4-16.2], P =.01); SF-36 bodily pain (48.8% vs. 25.6%; AOR 2.8 [1.1-7.3], P =.03); and SF-36 general health (20.9% vs. 7.0%; AOR 6.1 [1.1-33.0], P =.04). The surgery rate at 1 year was lower in the PT than in the HE group (7.0% vs. 23.3%; AOR 0.2 [0.04-0.9] P =.04).

Conclusions: Supervised PT greatly improved symptom severity and physical function than unsupervised exercise and was associated with lower likelihood of receiving surgery within 1 year.