Background: Spinal fusion is a common form of orthopedic surgery, the most common of which involves pedicle screw placement (PSP). Despite well-documented benefits, pedicle screws are associated with several intraoperative complications. This area of surgery has subsequently been recipient to many surgical developments. Currently, augmented reality surgical navigation (ARSN) is at the forefront of surgical interest. This systematic review evaluates whether, when compared to freehand, fluoroscopic, and intraoperative image-guided navigation, ARSN results in superior screw accuracy and operative outcomes for patients undergoing PSP surgery.

Methods: Data collection was performed on PubMed, Ovid MEDLINE, the Cochrane Library, Embase, and the Web of Science between January 7, 2023, and January 8, 2024. PRISMA guidelines were followed and the level of evidence was graded per the Centre for Evidence-Based Medicine's recommendations. Risk of bias was assessed per the ROBINS-I tool and the Cochrane guide for assessing study quality. A modified version of the Newcastle-Ottawa Scale was used to determine the certainty of the body of evidence.

Results: A total of 521 papers were obtained from all bibliographical databases, 31 of which were included in the final review. ARSN resulted in a significantly greater number of screws placed as Gertzbein and Robbins grade 1 or 2 (93.33% vs 85.86%, p<0.000), significantly reduced intraoperative blood loss (470.32 vs 802.44 ml, p=0.050), comparative operative duration (281.6 vs 255.5 min, p=0.819), comparative time to place a screw (2.71 vs 3.1 min, p=0.703), and a nonsignificant reduction in hospital stay (5.4 vs 7.5 days, p=0.097). Maximum follow-up was more than 14 days.

Conclusions: ARSN results in a significantly greater number of screws placed at Gertzbein-Robertson grade 1 or 2 than non-ARSN surgery. Therefore, ARSN can be considered as a safe and efficacious technical innovation within PSP surgery.

Background: Degenerative scoliosis is a progressive side-to-side deformity of the spine that is common in mature individuals, characterized by a Cobb angle of >10°. Current treatment options vary and can be categorized as conservative or non-conservative (surgery), with the primary goal of pain reduction. However, there is conflicting evidence regarding which treatment option is most effective. The aim of this study was to determine the effectiveness of braces in this group of subjects.

Methods: A systematic search was conducted in databases including PubMed, Web of Science, Scopus, and Embase for the period between 1950 and 2024. Keywords used were: (degenerative scoliosis OR adult scoliosis) AND (conservative treatment OR brace OR orthosis). The quality of the selected studies was evaluated using the Downs and Black tool.

Results: Of 500 papers identified in the search, a total of 11 studies were chosen for final analysis. Most of the selected studies focused on the effects of various types of braces on pain intensity, quality of life, and functional performance in subjects with degenerative scoliosis.

Conclusions: Based on the available literature and the lack of strong studies on the effectiveness of braces, it cannot be definitively concluded that the use of braces reduces the severity of scoliosis curves in adults with degenerative scoliosis. However, braces may have an impact on quality of life and pain severity in this group of subjects.

Background: Cortical bone trajectory screw (CBTS) is reported to offer increased cortical bone purchase and improved outcomes as compared to the traditional pedicle screw (PS), particularly in osteoporotic patients. The systematic review aims to compare randomized controlled trials comparing CBTS with PS in single-level lumbar spine fusion surgery.

Methods: A systematic search was conducted on PubMed (MEDLINE), Scopus, Embase, Web of Science, and Cochrane. Moreover, ClinicalTrials.gov, International Clinical Trials Registry Platform (ICTRP), and China National Knowledge Infrastructure (CNKI) were also searched. Outcome measures included fusion rates, complication rates, perioperative parameters, pain scores, and functionality. (PROSPERO: CRD42024523809).

Results: Four manuscripts, reporting on three randomized controlled trials (RCTs) and 416 patients, were included in this review. The follow-up ranged from 24 to 26 months postoperatively. All patients underwent single-level fusion only. There was no significant difference in the fusion rates between CBTS and PS at one-year (risk ratio [RR] 1.05 [0.97, 1.13], p=0.24) or two-year (RR 1.02 [0.96, 1.08], p=0.47) follow-ups. The CBTS group had a lower risk of intraoperative complications (RR 0.44 [0.32, 0.60], p<0.001) but an equal risk of postoperative complications (RR 0.71 [0.42, 1.22], p=0.22). There was no difference in pain, functionality, disability, and quality-of-life scores. CBTS group had better outcomes in incision length (mean difference [MD] -25.44 [-40.76, -10.12], p=0.001), operative time (MD -20.71 [-32.91, -8.51], p=0.009), and blood loss (MD -60.23 [-106.74, -13.72], p=0.01), while there was no difference in length of stay (MD -0.49 [-1.01, 0.04], p=0.07).

Conclusions: Although slightly favoring CBTS, RCTs were limited in number and had a serious risk of bias. Future RCTs should use superiority trial designs, have minimal bias, and include implant details, incidence of adjacent segment disease, and quality-of-life metrics.

Introduction: Surgical interventions for cervical spine and spinal cord diseases may lead to life-threatening postoperative airway obstruction, requiring urgent airway management. This study aimed to assess the feasibility and effectiveness of our respiratory management protocol for patients undergoing anterior cervical approaches, posterior occipitocervical fusion, and intramedullary tumor resection.

Methods: This single-center retrospective study consisted of 497 patients who underwent cervical surgeries, including anterior fusion, posterior occipitocervical fusion, combined anterior and posterior fusions, and intramedullary tumor resection between January 2006 and June 2022. Our institution implemented a specific postoperative airway management protocol from September 2014 onward. The protocol involved continued intubation for at least the first postoperative night, followed by a spontaneous breathing trial with a cuff leak test and extubation one or more days after surgery. We compared the outcomes between the pre-protocol period (non-protocol group, n=234) and the protocol period (protocol group, n=263).

Results: There were no significant between-group differences regarding demographic, clinical, or surgical details. In the non-protocol group, four subjects required reintubation because of postoperative airway complications (anterior fusion: 1 patient, posterior occipitocervical fusion: 1 patient, and intramedullary tumor resection: 2 patients). After the airway protocol implementation, the reintubation rate dropped to zero (P=0.048).

Conclusions: Our airway management protocol substantially reduced the need for reintubation. These findings emphasize the importance of postoperative respiratory management after cervical spine surgeries and underscore the need for appropriate measures to prevent complications.

Introduction: Proper cervical sagittal alignment is essential for maintaining overall spinal stability and function. A crucial measure of this alignment is the T1 slope, which is an important indicator. However, lateral cervical spine radiographs often fail to clearly show the T1 slope owing to several factors, such as shoulder anatomy or variations in body shape. In this study, we aimed to evaluate the differences in cervical alignment between individuals with visible and invisible T1 slopes.

Methods: This study was a retrospective cohort analysis involving 60 patients diagnosed with cervical spine conditions and evaluated via radiographic imaging. The patients were categorized into two groups based on whether the T1 slope was clearly visible or not. Key radiographic measurements, such as the C2-C7 sagittal vertical axis (SVA) and C2-C7 Cobb angles in the neutral, flexion, and extension postures, were recorded and statistically analyzed.

Results: Significant differences were observed in the C2-C7 SVA between the groups, particularly among men. Men in the invisible T1 slope group had an average SVA of 28.9 mm, whereas those in the visible group had a mean SVA of 16.0 mm (P<0.05). Although no notable differences were observed in the Cobb angles for the neutral and flexion positions, a substantial reduction in the extension Cobb angle was noted in the invisible than in the visible group (24.4° vs. 37.6°, P<0.05).

Conclusions: Male patients with obscured T1 slopes exhibited unique radiographic features, including higher C2-C7 SVA and diminished extension capacity. This suggests that the visibility of the T1 slope plays a pivotal role in the evaluation of cervical alignment. Furthermore, the exclusion of patients with an invisible T1 slope from research studies could lead to biased results.

Introduction: Cervical pedicle screw (CPS) placement is crucial for posterior cervical fusion surgery due to its strong fixation ability. However, CPS insertion is associated with risks, including screw perforation, which can lead to complications such as vertebral artery injury and neurological deficits. Although previous studies have explored some morphological factors affecting CPS placement, comprehensive data on specific parameters contributing to perforation remains limited. This study aimed to investigate cervical vertebrae features associated with CPS perforation and established threshold values for improved preoperative planning.

Methods: A retrospective analysis of 36 patients who underwent posterior cervical fusion surgery with CPS placement was conducted using preoperative computed tomography (CT) -based navigation. Cases with CPS insertion at C1 or C2 were excluded. The key morphological parameters-optimal screw trajectory angle, pedicle diameter, and distance from the entry point to the pedicle isthmus (DEP) -were measured on preoperative CT images. CPS placement accuracy was assessed postoperatively using Neo's classification. The receiver operating characteristic (ROC) curve analysis determined the cutoff values for predicting CPS perforation.

Results: Among the 102 CPSs placed from C3 to C7, the overall perforation rate was 25.5%. C3 had the highest perforation rate (45.5%), whereas C7 had the lowest (3.1%). The vertebrae with CPS perforation exhibited a significantly larger optimal screw trajectory angle (45.5° vs. 38.0°, p<0.001), smaller pedicle diameter (4.2 mm vs. 5.2 mm, p<0.001), and longer DEP (13.2 mm vs. 11.9 mm, p=0.002). The ROC analysis identified the following cutoff values: 44.0° for the optimal angle, 4.35 mm for the pedicle diameter, and 12.7 mm for the DEP. These morphological parameters strongly predicted the risk of CPS perforation.

Conclusions: Establishing key morphological thresholds enhances preoperative planning for CPS placement, improves accuracy and patient safety, and minimizes complications.

Introduction: Thoracic ossification of the ligamentum flavum (T-OLF), which leads to neurological impairment, is a rare pathologic entity. Open posterior laminectomy is the gold standard treatment for T-OLF. However, the high rates of postoperative complications and perioperative morbidity have raised many concerns among surgeons. This study presented a series of patients with symptomatic single-level T-OLF who underwent posterior decompression using biportal endoscopic spinal surgery (BESS). The objective of this study was to demonstrate our procedure using BESS for T-OLF resection and to evaluate its safety and efficacy.

Methods: We retrospectively reviewed patients who previously underwent thoracic posterior decompression with BESS between February 2021 and March 2023. Neurological status was assessed using the revised Japanese Orthopedic Association (JOA) score for thoracic myelopathy before surgery and at the final follow-up, along with the recovery rate (RR) at the final follow-up. The radiological outcome was evaluated by measuring the cross-sectional area (CSA) of the spinal canal from the T2 axial images at the most stenotic level, before and after surgery.

Results: Twenty patients (8 male and 12 female; aged between 38 and 79 years) were enrolled in this study. The mean operation time was 89.7±21.8 min. The average JOA score was 5.6±1.1 before surgery and 9.1±1.0 at the final follow-up. The average RR at the final follow-up was 65.6%. Outcomes were classified as excellent in six patients (30.0%), good in nine patients (45.0%), and moderate in five patients (25.0%), with no cases categorized as fair or worsened (0%). The mean preoperative and postoperative CSA were 0.92±0.14 cm² and 1.38±0.22 cm², respectively.

Conclusions: BESS is a safe, effective, and minimally invasive alternative to conventional open surgery for single-level T-OLF.

Introduction: Despite an increase in the demand for surgical treatment of elderly patients with degenerative spinal disorders, little is known about mortality following spinal surgery in this population. This study aims to identify the incidence and causes of in-hospital mortality in elderly patients after elective spine surgery.

Methods: We extracted the data of patients aged ≥65 years who underwent elective spine surgery between December 12, 2016, and May 31, 2022, from our prospective multicenter cohort. The primary outcome was the in-hospital mortality rate. Univariate analysis was conducted to identify potential risk factors for postoperative mortality. The detailed clinical course of patients who died was retrospectively investigated using medical records.

Results: A total of 10,976 eligible patients (5,976 males and 5,000 females), with a mean age of 75.5 years, were identified. There were eight in-hospital deaths (0.07%). Univariate analyses showed that the eight patients were significantly older (82.1 years vs. 75.5 years, P=0.008), were more frequently hemodialysis-dependent (50.0% vs. 2.9%, P<0.001), and had a higher proportion of cases with cervical surgery (62.5% vs. 17.0%, P<0.001) and preoperative American Society of Anesthesiologists Physical Status ≥3 (87.5% vs. 14.6%, P<0.001). Death occurred at a median of 24.5 days postoperatively. The causes of in-hospital death were as follows: gastrointestinal diseases in five cases (ischemic colitis in three cases, panperitonitis in one, and intestinal perforation in one), sepsis due to unknown causes in two, and lethal arrhythmia in one. The initial symptoms preceding the lethal clinical course were mainly common gastrointestinal symptoms, such as abdominal pain, anorexia, diarrhea, and vomiting.

Conclusions: The main cause of in-hospital mortality was gastrointestinal disease. Surgeons should be aware that common gastrointestinal symptoms can be the initial symptoms of a subsequent lethal clinical course in elderly patients.

Introduction: Cage subsidence (CS) after posterior or transforaminal lumbar interbody fusion (PLIF or TLIF) is challenging; however, its impact on health-related quality of life (HRQOL) remains unclear. This study aimed to explore the impact of CS occurrence on HRQOL and identify the risk factors in patients following PLIF or TLIF.

Methods: A total of 138 patients (mean age, 67 years; follow-up period, 12 months) who underwent single-level PLIF or TLIF were retrospectively analyzed. CS was defined as >1 mm sinking of the intervertebral cage evaluated via computed tomography. The patients were divided into the CS and nonsubsidence (NS) groups. HRQOL was assessed using the Oswestry Disability Index (ODI) scores.

Results: Among the 138 patients, 30 (22%) developed CS following PLIF or TLIF. All cases with TLIF surgery (n=25) involved the use of one cage. A significant difference was observed in the use of two cages between the CS and NS groups (20.0% vs. 48.1%; P=0.006). The CS group had lower occupancy rate of autograft soon after the operation than the NS groups (P=0.002), and the occupancy rate of autograft tended to decrease in the CS group compared with the NS group over time. The ODI scores improved in both groups postoperatively; however, the NS group exhibited greater improvements in ODI scores from 4 months postoperatively. The CS group had a significantly lower proportion of patients with intervertebral osseous union at 6 and 12 months postoperatively compared with the NS group (P=0.003 and P<0.001, respectively).

Conclusions: The use of two intervertebral cages may enhance initial stability and reduce CS risk after PLIF. Initial intervertebral stability was crucial to preventing CS occurrence, as evidenced by the high occupancy rates of autograft in patients without CS. Surgical factors, including surgical strategy and intraoperative techniques, should be considered to prevent CS occurrence and to improve surgical outcomes and patient satisfaction.

Introduction: Spinal alignment in women with osteoporosis tends to deteriorate with advancing age, and this misalignment may serve as an indicator of future fall-related fractures. Vertebral fractures, which commonly occur in patients with osteoporosis, have distinct characteristics compared with other fall-related fractures and should therefore be separately evaluated. This study aimed to investigate the association between future fall-related fractures and sagittal spinal alignment, excluding vertebral fractures.

Methods: A total of 333 women with osteoporosis were recruited and followed up between November 2013 and July 2024. At baseline, information on medication status and bone mineral density in the lumbar spine and femoral neck was obtained from the patients' medical record. Furthermore, the locomotive syndrome (LOCOMO) stage was assessed via risk tests, and sagittal alignment parameters, including sagittal vertical axis (SVA), thoracic kyphosis (TK), pelvic incidence (PI), and lumbar lordosis (LL), were evaluated. In addition, Cox proportional hazards regression analysis was conducted to determine the risk of fall-related fractures based on all variables.

Results: The mean follow-up period was 5.4 years. The final sample for assessing fall-related fracture incidence consisted of 214 participants. Fall-related fractures occurred in 31 of the 333 participants (9.3%). Cox proportional hazards regression analysis, adjusted for all variables, revealed that SVA (hazard ratio [HR]=1.011, 95% confidence interval [CI] 1.003-1.02), LL (HR=1.039, 95% CI 1.007-1.072), LOCOMO stage (HR=1.801, 95% CI 1.127-2.879), and presence of parathyroid hormone (HR=0.165, 95% CI 0.031-0.891) are independent risk factors for future fall-related fractures.

Conclusions: Awareness of fall-related fracture risks can be increased by monitoring the SVA, LL, and LOCOMO stage as well as administering parathyroid hormone medications. While the deterioration of sagittal spinal alignment is a well-known factor in vertebral fractures, this study suggests that future fall-related fractures, excluding vertebral fractures, are influenced by sagittal spinal alignment.

Introduction: Adult spinal deformity (ASD) is prevalent among older adults, considerably affecting their quality of life. Although surgical interventions are effective, they have high complication rates and medical costs. Furthermore, there is a lack of evidence supporting the effectiveness of nonsurgical treatments (e.g., physical therapy) in patients with ASD. This study aimed to investigate the impact of "Koshimagari exercise," a specific home-based exercise regimen designed for patients with ASD, and to evaluate its effects on clinical outcomes in older adults.

Methods: A total of 144 participants aged 50-80 years with chronic low back pain (LBP) due to spinal deformities were included in this multicenter prospective study. Qualified physiotherapists conducted intervention sessions at the hospital once a week, and self-exercise was performed at home three times a week. After 3 months, the frequency of self-exercise at home increased to four times a week. Clinical evaluations were conducted using the Oswestry Disability Index (ODI), five-level classification system of EuroQol-5 Dimensions (EQ-5D), Japanese edition of Scoliosis Research Society-22r (SRS-22r), and visual analog scale (VAS) for LBP at baseline and 3, 6, and 12 months. Radiographic evaluations were performed in standing and supine positions.

Results: Of 130 participants who provided written informed consent, 98 completed the 6-month follow-up and were included in the analysis. Significant improvements observed in ODI, EQ-5D, and VAS scores were observed at 3 months, with SRS-22r scores improving throughout the study period. Radiographically, there were significant differences in the sagittal vertical axis and pelvic tilt at 12 months. Sufficient compliance with the self-exercise program was reported by 96%, 86%, and 73% of participants at 3, 6, and 12 months, respectively.

Conclusions: The "Koshimagari Exercise" program led to significant short-term improvements in health-related quality of life and pain among elderly patients with ASD. This home-based self-exercise program is an excellent nonsurgical treatment option for patients with ASD.

Introduction: Chemonucleolysis with condoliase (chondroitin sulfate ABC endolyase) has been widely employed to treat patients with lumbar disc herniation (LDH) in Japan. Although it is an effective and relatively safe treatment for radicular neuropathy in patients with LDH, there have been no reports that investigate how severe low back pain (LBP) changes after condoliase injection. In this multicenter study, the effectiveness of condoliase injection for reducing severe LBP in patients with LDH was evaluated.

Methods: This retrospective study involved patients treated with intradiscal condoliase injection for LDH at nine participating centers. Patients were diagnosed with subligamentous-type herniation based on pretreatment MRI. Patients with severe LBP (defined as a preinjection numeric rating scale [NRS] for LBP greater than or equal to that for leg pain) were categorized into the LBP group. Demographic data, adverse events, treatment costs, and the NRS for LBP and lower extremity pain were analyzed. A 50% response was defined as ≥50% improvement in the NRS at 1 year postinjection. On the basis of the Pfirman classification, the LBP group was divided into less-degenerative (Grades II and III) and degenerative (Grades IV and V) subgroups.

Results: Seventy-nine patients were classified into the LBP group. Of these patients, 61 (77.2%) showed a >50% reduction in LBP, and another 61 (77.2%) demonstrated a >50% reduction in lower extremity pain. Improvement of lower limb pain was considerably better in the less-degenerative group than in the degenerative group, whereas that of low back pain was similar between the two subgroups. Medical costs, which include remuneration for injection, drug fees, inpatient costs, and other expenses, were similar between the LBP group and all cases.

Conclusions: This retrospective multicenter study revealed that patients with LDH with severe LBP frequently experienced improvement in radicular pain and LBP, which is similar to LDH cases without severe LBP.

Introduction: Lumbar spondylolysis (LS) is a stress fracture of the pars interarticularis that can occur in adolescents. Both early- and progressive-stage LS can be successfully treated with conservative therapy consisting of activity modification and external bracing; however, conservative therapy is not suitable for athletes who hope for an early return to sports. We introduce a novel, minimally invasive surgical technique for the treatment of LS that enables an early return to sports and describe surgical results, including bone union rates, time of both bone unions, and return to sports.

Technical Note: To facilitate an early return to sports in adolescent athletes with early-to-progressive-stage LS, we developed a percutaneous spondylolysis repair technique using cannulated compression headless screws with a cortical bone trajectory. Fourteen adolescent athletes underwent this technique; as a result, all athletes achieved bone union and returned to sports within 3 months.

Conclusions: This minimally invasive surgical technique for LS can achieve early bone union in adolescent athletes, thereby facilitating an early return to sports.