Background: Osteoporosis is common among elderly patients and can result in vertebral fractures requiring surgical treatment. This study assessed clinical outcomes associated with spinal surgery in patients with osteoporosis/osteopenia with an additional focus on Asian patients.

Methods: A PRISMA-compliant systematic review and meta-analysis were conducted using the PubMed and ProQuest databases to identify articles published up to May 27, 2021, that included outcomes for patients with osteoporosis or osteopenia undergoing spinal surgery. Statistical analysis was conducted comparing rates of proximal junctional kyphosis (PJK) /proximal junctional failure (PJF), implant loosening, and revision surgery. A qualitative summary of Asian studies was also conducted.

Results: A total of 16 studies comprising 133,086 patients were included; among the 15 studies reporting rates of osteoporosis/osteopenia, 12.1% (16,127/132,302) of patients overall and 38.0% (106/279) of Asian patients (n=4 studies) had osteoporosis/osteopenia. The risks of PJK/PJF (relative risk [RR]=1.89; 95% confidence interval [CI]=1.22-2.92, p=0.004), screw loosening (RR=2.59; 95% CI=1.67-4.01, p<0.0001), and revision surgery (RR=1.65; 95% CI=1.13-2.42, p=0.010) were higher in patients with poor bone quality compared with those with healthy bone. In the qualitative review of Asian studies, all studies found that osteoporosis increased the risk of complications and/or revision for spinal surgery patients.

Conclusions: This systematic literature review and meta-analysis indicate that spinal surgery patients with compromised bone quality have more complications and higher healthcare utilization than those with normal bone quality. To our knowledge, this is the first study to focus on the pathophysiology and disease burden among Asian patients. Given the high rate of poor bone quality in this aging population, additional high-quality Asian studies, with uniform definitions and data reporting, are needed.

Background: Thoracolumbar burst fractures (BFs) are traumatic lesions instigated by compression forces. Canal compression and compromise may lead to neurological deficits. Optimal surgical management is yet to be fully defined since various approaches such as anterior, posterior, or combined exist. This study aims to determine the operative performance of these three treatment modalities.

Methods: In accordance with the PRISMA guidelines, a systematic review was performed, identifying studies comparing anterior, posterior, and/or combined surgical approaches in patients with thoracolumbar BFs. To analyze available evidence, a Bayesian network meta-analysis framework was utilized.

Results: In this study, 16 studies were included. The shortest operative times and lowest operative blood losses were found for a posterior approach. The length of stay (LoS) was shorter with the posterior approach compared with the other two modalities. Return to work, postoperative kyphotic angle (PKA), and complications all favored the posterior approach. The visual analog scale score was similar between groups.

Conclusions: This study suggests that the posterior approach has significant advantages in terms of operative time, blood loss, LoS, PKA, return to work, and complication rates when compared to the other approaches. Treatment should remain an individualized process, and before choosing an approach, factors such as patient characteristics, surgeon experience, and hospital settings should be considered.

Introduction: This retrospective cohort study aimed to examine the nutritional time course and elucidate the critical period of undernutrition following acute traumatic cervical spinal cord injury (CSCI).

Methods: The study was performed at a single facility that treated spinal cord injuries. We examined individuals with acute traumatic CSCI admitted to our hospital within 3 days of injury. Both prognostic nutritional index (PNI) and controlling nutritional status (CONUT) scores, which objectively reflect nutritional and immunological conditions, were assessed at admission and 1, 2, and 3 months after the injury. The American Spinal Injury Association impairment scale (AIS) categorizations and severity of dysphagia were evaluated at these time points.

Results: A total of 106 patients with CSCI were evaluated consecutively for 3 months after injury. Individuals with AIS categorizations of A, B, or C at 3 days after injury were significantly more undernourished than those with an AIS categorization of D at 3 months after injury, indicating that individuals with mild paresis better maintained their nutritional condition after injury. Nutritional conditions, as assessed by both PNI and CONUT scores, improved significantly between 1 and 2 months after injury, whereas no significant differences were found between admission and 1 month after injury. Nutritional status and dysphagia were significantly correlated at each time point (p<0.001), indicating that swallowing dysfunction is an important factor associated with malnutrition.

Conclusions: Nutritional conditions showed significant gradual improvements from 1 month after the injury. We must pay attention to undernutrition, which is associated with dysphagia, especially in individuals with severe paralysis during the acute phase following injury.

Introduction: Only a few reports have described the clinical features of recurrent spinal cord tumors. This study aimed to report the recurrence rates (RRs), radiographic imaging, and pathological features of various histopathological recurrent spinal cord tumors using a large sample size.

Methods: This study adopted the retrospective observational study design using a single-center study setting. We retrospectively reviewed 818 consecutive individuals operated for spinal cord and cauda equina tumors between 2009 and 2018 in a university hospital. We first determined the number of surgeries and then the histopathology, duration to reoperation, number of surgeries, location, degree of tumor resection, and tumor configuration of the recurrent cases.

Results: A total of 99 patients (46 men and 53 women) who underwent multiple surgeries were identified. The mean duration between the primary and second surgeries was 94.8 months. A total of 74 patients underwent surgery twice, 18 patients thrice, and 7 patients 4 or more times. The recurrence sites were broadly distributed over the spine, with mainly intramedullary (47.5%) and dumbbell-shaped (31.3%) tumors. The RRs for each histopathology were as follows: schwannoma, 6.8%; meningioma and ependymoma, 15.9%; hemangioblastoma, 15.8%; and astrocytoma, 38.9%. The RRs after total resection were significantly lower (4.4%) than that after partial resection. Neurofibromatosis-associated schwannomas had a higher RR than sporadic schwannomas (p<0.001, odds ratio [OR]=8.54, 95% confidence interval [95% CI]: 3.67-19.93). Among the meningiomas, the RR increased to 43.5% in ventral cases (p<0.001, OR=14.36, 95% CI: 3.66-55.29). Within the ependymomas, partial resection (p<0.001, OR=2.871, 95% CI: 1.37-6.03) was found to be significantly correlated with recurrence. Dumbbell-shaped schwannomas exhibited a higher RR than non-dumbbell-shaped ones. Furthermore, dumbbell-shaped tumors other than schwannoma had a higher RR than dumbbell-shaped schwannomas (p<0.001, OR=16.0, 95% CI: 5.518-46.191).

Conclusions: Aiming for total resection is essential to prevent recurrence. Dumbbell-shaped schwannomas and ventral meningiomas exhibited higher RR requiring revision surgery. As for dumbbell-shaped tumors, spinal surgeons should pay attention to the possibilities of non-schwannoma histopathologies.

Introduction: Clinical evidence shows that opioid administration in cancer patients is associated with shorter survival. This study explored the impact of opioid requirement on overall survival of patients with spinal metastases. We also evaluated the association between opioid requirement and tumor-related spinal instability.

Methods: We retrospectively identified 428 patients who had been diagnosed with spinal metastases from February 2009 to May 2017. Those with an opioid prescription during the first 1 month after the diagnosis were included in this study. Patients given opioids were divided into two groups: the opioid requirement group [≥5 mg oral morphine equivalent (OME) /day] and the nonopioid group (<5 mg OME/day). Spinal instability due to metastases was evaluated using the Spinal Instability Neoplastic Score (SINS). Cox proportional hazards analysis was performed to evaluate the relationship between opioid use and overall survival.

Results: The most frequent primary cancer site was the lung, in 159 patients (37%), followed by the breast in 75 (18%) and the prostate in 46 (11%). Multivariate analyses showed that patients who required ≥5 mg OME/day were approximately twofold more likely to die after a spinal metastases diagnosis than those who required <5 mg OME/day (hazard ratio 2.13; 95% confidence interval 1.69-2.67; p<0.001). The SINS was significantly higher in the opioid requirement group than those in the nonopioid group (p<0.001).

Conclusions: For patients with spinal metastases, opioid requirement was associated with shorter survival, independently of known prognostic factors. The patients were also more likely to have tumor-related spinal instability than those in the nonopioid group.

Introduction: Despite recent advances in applied instruments and surgical techniques, the incidence of iatrogenic durotomies caused by traditional techniques remains significant. The ultrasonic bone scalpel (UBS) has been shown to improve speed and reduce complications in laminectomies in the cervical and thoracic spine when compared to traditional methods utilizing high-speed burr, punch forceps, or rongeurs. Thus, in this study, we aim to evaluate whether the use of the UBS in the lumbar spine would result in equivalent safety, efficacy, and patient-reported outcomes (PROs) improvement when compared to traditional methods of laminectomy.

Methods: Data from a prospectively collected, single-institution registry was queried between January 1, 2019 and September 1, 2021 for patients with a primary diagnosis of lumbar stenosis who received a laminectomy (with or without fusion) using traditional methods or UBS method. Outcomes included 3-month and 12-month values for all PROs Measurement Information System (PROMIS) subdomains, Numerical Rating Scale (NRS) pain score, Oswestry Disability Index (ODI) percentage, Patient Health Questionnaire 9 (PHQ-9) score, operative complications, reoperations, and readmissions. Covariates selected for matching included age, operation type, and number of levels. A variety of statistical tests were utilized.

Results: As per our findings, 2:1 propensity matching resulted in 64 "traditional group" patients and 32 "UBS group" patients. Post-match analysis found no differences between the traditional and UBS groups for demographic and baseline measures except for race and ethnicity. For the matched sample, no differences were noted in PROs, reoperations, or readmissions. There was a significant difference in rates of durotomies between the traditional and UBS groups (12.5% vs. 0.0%, p=0.049).

Conclusions: Results showed the high-frequency oscillation technology implemented by the UBS helps to decrease the rate of injury to the dura, thus reducing the overall incidence of iatrogenic durotomies. We believe these data provide valuable information to surgeons and patients about the safety and efficacy of the UBS in performing lumbar laminectomies.

Introduction: Lateral lumbar interbody fusion (LLIF) has been introduced in Japan in 2013. Despite the effectiveness of this procedure, several considerable complications have been reported. This study reported the results of a nationwide survey performed by the Japanese Society for Spine Surgery and Related Research (JSSR) on the complications associated with LLIF performed in Japan.

Methods: JSSR members conducted a web-based survey following LLIF between 2015 and 2020. Any complications meeting the following criteria were included: (1) major vessel, (2) urinary tract, (3) renal, (4) visceral organ, (5) lung, (6) vertebral, (7) nerve, and (8) anterior longitudinal ligament injury; (9) weakness of psoas; (10) motor and (11) sensory deficit; (12) surgical site infection; and (13) other complications. The complications were analyzed in all LLIF patients, and the differences in incidence and type of complications between the transpsoas (TP) and prepsoas (PP) approaches were compared.

Results: Among the 13,245 LLIF patients (TP 6,198 patients [47%] and PP 7,047 patients [53%]), 389 complications occurred in 366 (2.76%) patients. The most common complication was sensory deficit (0.5%), followed by motor deficit (0.43%) and weakness of psoas muscle (0.22%). Among the patient cohort, 100 patients (0.74%) required revision surgery during the survey period. Almost half of the complications developed in patients with spinal deformity (183 patients [47.0%]). Four patients (0.03%) died from complications. Statistically more frequent complications occurred in the TP approach than in the PP approach (TP vs. PP, 220 patients [3.55%] vs. 169 patients [2.40%]; p<0.001).

Conclusions: The overall complication rate was 2.76%, and 0.74% of the patients required revision surgery because of complications. Four patients died from complications. LLIF may be beneficial for degenerative lumbar conditions with acceptable complications; however, the indication for spinal deformity should be carefully determined by the experience of the surgeon and the extent of the deformity.

Introduction: Conventional magnetic resonance imaging findings frequently do not correlate with the symptoms of lumbar disc herniation (LDH). Diffusion-weighted imaging can reveal important details about the microstructure of tissues. This study assessed the role of diffusion-weighted imaging (DTI) in LDH with radiculopathy and explored the relationship between DTI values and clinical scores.

Methods: Forty-five patients with LDH with radiculopathy were evaluated via DTI at the intraspinal (IS), intraforaminal (IF), and extraforaminal (EF) levels. A visual analog scale (VAS) was used for low back and leg pain. The Japanese Orthopaedic Association (JOA) scoring system, Oswestry Disability Index (ODI), and Roland-Morris Disability Questionnaire (RMDQ) were used for functional evaluation.

Results: There was a statistically significantly (p<0.05) difference between the apparent diffusion coefficient (ADC) and fractional anisotropy (FA) values on the affected side compared with those on contralateral normal side. The VAS score had a weak positive correlation with RMDQ score (r=0.279, P=0.050). The JOA score had a moderate negative correlation with RMDQ score (r=-0.428, P=0.002), whereas the ODI score had a moderate positive correlation with RMDQ score (r=0.554, P<0.001). There was a moderate positive correlation between ADC values at the IF level and the RMDQ score on the affected side (r=0.310, P=0.029). There was no correlation between FA values and JOA score. ODI had a significantly positive correlation with the contralateral normal side FA values at the IF (r=0.399, P=0.015), EF (r=0.368, P=0.008) and IS (r=0.343, P=0.015) levels. RMDQ had a weak positive correlation with the contralateral normal side FA values at the IF (r=0.311, P=0.028), IS (r=0.297, P=0.036) and EF (r=0.297, P=0.036) levels.

Conclusions: The decrease in FA values and the increase in ADC values are useful markers of compression. ADC correlates well with the patient's neurological symptoms and functional status. Conversely, FA correlates well with the patient's neurological symptoms, but is not correlated well with the functional status.

Introduction: Patients with nonidiopathic scoliosis often have a high risk associated with general anesthesia because of cardiac or pulmonary dysfunction secondary to underlying diseases. Base excess has been reported as a predictor in the management of trauma and cancer, although not yet in scoliosis. This study was performed to clarify the surgical outcomes and the association of perioperative complications with base excess in patients with nonidiopathic scoliosis who have a high risk associated with general anesthesia.

Methods: Patients with nonidiopathic scoliosis who were referred to our institution from 2009 to 2020 because of their high risk associated with general anesthesia were retrospectively enrolled. High-risk factors for anesthesia were determined by a senior anesthesiologist and categorized into circulatory or pulmonary dysfunction. Perioperative complications were analyzed using the Clavien-Dindo classification; severe complications were defined as grade ≥III. We investigated high-risk factors for anesthesia, underlying diseases, preoperative and postoperative Cobb angle, surgery-related factors, base excess, and postoperative management. These variables were statistically compared between patients with and without complications.

Results: Thirty-six patients (mean age, 17.9 years old; range, 11-40 years old) were enrolled (two patients declined surgery). High-risk factors were circulatory dysfunction in 16 patients and pulmonary dysfunction in 20 patients. The mean Cobb angle improved from 85.1° (36°-128°) preoperatively to 43.6° (9°-83°) postoperatively. Three intraoperative complications and 23 postoperative complications occurred in 20 (55.6%) patients. Severe complications occurred in 10 (27.8%) patients. All patients underwent postoperative intensive care unit management after posterior all-screw construction. A large preoperative Cobb angle (p=0.021) and base excess outliers (>3 or <−3 mEq/L) (p=0.005) were significant risk factors for complications.

Conclusions: Patients with nonidiopathic scoliosis who have a high risk associated with general anesthesia have a higher complication rate. Preoperative large deformity and base excess (>3 or <−3 mEq/L) could be predictors of complications.

Introduction: Mechanical complications, such as rod fracture (RF) and proximal junctional kyphosis (PJK), commonly occur after adult spinal deformity (ASD) surgery. A rigid construct is preferred to prevent RF, whereas it is a risk factor for PJK. This controversial issue urged us to conduct a biomechanical study for seeking the optimal construct to prevent mechanical complications.

Methods: A three-dimensional nonlinear finite element model, which consisted of the lower thoracic and lumbar spine, pelvis, and femur, was created. The model was instrumented with pedicle screws (PSs), S2-alar-iliac screws, lumbar interbody fusion cages, and rods. Rod stress was measured when a forward-bending load was applied at the top of the construct to evaluate the risk of RF in constructs with or without accessory rods (ARs). In addition, fracture analysis around the uppermost instrumented vertebra (UIV) was performed to assess the risk of PJK.

Results: Changing the rod material from titanium alloy (Ti) to cobalt chrome (CoCr) decreased shearing stress at L5-S1 by 11.5%, and adding ARs decreased it by up to 34.3% (for the shortest ARs). Although the trajectory (straightforward vs. anatomical) of PSs did not affect the fracture load for UIV+1, changing the anchor from PSs to hooks at the UIV reduced it by 14.8%. Changing the rod material from Ti to CoCr did not alter the load, whereas the load decreased by up to 25.1% as the AR became longer.

Conclusions: The PSs at the UIV in the lower thoracic spine, CoCr rods as primary rods, and shorter ARs should be used in long fusion for ASD to prevent mechanical complications.