Numerous studies have explored the connection between lumbar osteophytes, their pathophysiology, and instability since Macnab's 1971 report on traction spurs as an indicator of lumbar instability. This study provides a narrative historical overview of traction spurs, a classic finding that suggests lumbar instability. It summarizes the causes of anterior lumbar vertebral osteophytes, the relationship between traction spurs and lumbar spinal instability, and the clinical significance of traction spurs. Vertebral osteophytes are grouped into two categories, namely, traction spurs or claw spurs, which represent different stages of the same pathological process. Traction spurs are indicative of instability and occur in the early stage of disc degeneration, characterized by temporary dysfunction or instability. Traction spur formation following fusion surgery can predict union or nonunion, and it serves as an indicator of preoperative and postoperative segmental instability. The relationship between traction spurs and radiographic instability, as well as their association with imaging findings such as CT and MRI, has been clarified. Additionally, finite element analysis and mechanical testing have been used to investigate the significance of traction spurs. However, further research is needed to verify that traction spurs are an accurate indicator of pre- and postoperative lumbar instability.

Background: Intradiscal condoliase injection for lumbar disc herniation (LDH) was developed in Japan in 2018. The treatment is intermediate between conservative therapy and surgery, and its frequency is increasing. Condoliase is limited to a single application over a lifetime, rendering it important to understand the indications and predictors of its effectiveness. This review aimed to summarize published studies and provide appropriate indications and limitations for appropriate patient selection based on existing findings.

Methods: While adhering to PRISMA guidelines, we searched the PubMed, Web of Science, and EMBASE databases to identify articles reporting the clinical outcomes of intradiscal condoliase injection for LDH. Data extraction focused on the effective rate, prognostic factors, and posttreatment imaging changes and was used in the meta-analysis.

Results: Nineteen studies met the inclusion criteria. Our meta-analysis revealed 78% total response, 11% posttreatment surgery, and 42% posttreatment Pfirrmann-classification-grade progression rates. Posttreatment intervertebral disc degeneration was potentially associated with an improved response rate and disc regeneration one year posttreatment, especially in young patients. The Regimen for patients aged <20 and >70 years should be carefully selected, including those with a disease duration of >1 year, recurrent LDH, small-sized LDH, vertebral instability, and inadequate duration (<3 months) of conservative therapy.

Conclusions: Although long-term outcomes and imaging changes must be evaluated owing to the heterogeneity of previous studies, intradiscal condoliase injection is a minimally invasive and cost-effective treatment option for patients with LDH. Treatment indications should be determined after carefully evaluating evidence from previous conservative and surgical treatments.

Lumbar interbody fusion (LIF) is a surgical procedure for treating lumbar spinal stenosis and deformities. It removes a spinal disc and insert a cage or bone graft to promote solid fusion. Extensive research on LIF has been supported by numerous animal studies, which are being developed to enhance fusion rates and reduce the complications associated with the procedure. In particular, the anterior approach is significant in LIF research and regenerative medicine studies concerning intervertebral discs, as it utilizes the disc and the entire vertebral body. Several animal models have been used for anterior LIF (ALIF), each with distinct characteristics. However, a comprehensive review of ALIF models in different animals is currently lacking. Medium-sized and large animals, such as dogs and sheep, have been employed as ALIF models because of their suitable spine size for surgery. Conversely, small animals, such as rats, are rarely employed as ALIF models because of anatomical challenges. However, recent advancements in surgical implants and techniques have gradually allowed rats in ALIF models. Ambitious studies utilizing small animal ALIF models will soon be conducted. This review aims to review the advantages and disadvantages of various animal models, commonly used approaches, and bone fusion rate, to provide valuable insights to researchers studying the spine.

Introduction: Guidelines published in 2013 recommend early closed reduction for cervical spine dislocation. There are two types of closed reduction: manual reduction and traction. Manual reduction can be performed early. In addition, it can correct rotation and requires a short time for complete reduction. We perform manual reduction for cervical spine dislocation. This study aimed to evaluate early manual reduction's success rate and safety for cervical dislocation. We also examined the relationship between time to reduction and improvement in paralysis.

Methods: This retrospective cohort study included 361 patients with cervical spine injuries treated at our hospital between July 2010 and December 2021. We assigned patients to the early group if the time from injury to reduction was ≤6 hours and to the late group if >6 hours. We performed awake manual reduction on the patients. Furthermore, we compared reduction's success rate and safety, including neurological outcomes.

Results: Overall, 46 patients were included in the study: 31 and 15 in the early and late groups, respectively. The success rate of reduction was 93%, and no neurological complications from reduction were observed. The neurological outcomes and reduction success rates were significantly superior in the early group than in the late group.

Conclusions: Neurological outcomes were significantly superior when reduction was performed within 6 hours than after 6 hours. Manual reduction can be performed early, safely, and easily. It is effective for cervical spine dislocation requiring early reduction for an excellent neurologic prognosis.

Introduction: This study investigates the outcomes of treating neglected unstable Hangman's fractures through a single-stage Anterior Cervical Discectomy and Fusion (ACDF) procedure with tricortical iliac crest bone grafts.

Methods: Five patients with neglected unstable Hangman's fractures, treated at our institution between March 2012 and March 2017, underwent C2-C3 ACDF. Functional outcomes were assessed using the Visual Analog Scale (VAS) score and Neck Disability Index (NDI), and neurological evaluation was done using the American Spinal Injury Association (ASIA) grading system. The radiological assessment included serial plain radiographs and a computed tomography scan at a 12-month follow-up.

Results: Postoperatively, C2-C3 angulation improved significantly, decreasing from 15° to 4.4°, and sagittal translation improved from 4.2 mm to 2 mm. The VAS score improved from 6.4 to 1.4 at 24 months postsurgery. Concurrently, NDI decreased from 70.4% to 14.8%. Fusion occurred in an average of 5.6 months. Neurologically, one patient improved from ASIA grade D to grade E, while the other four retained their grade E status.

Conclusions: A single-stage ACDF with autologous iliac crest bone grafts is an effective surgical option for neglected type II/IIA Hangman's fractures, yielding satisfactory functional and radiological outcomes. This technique significantly corrects anterior translation and angulation, even in neglected cases, with the aid of intraoperative skull traction and plate reduction.

Introduction: Anterior cervical discectomy and fusion (ACDF) has proven to be a clinically efficient and cost-effective method for treating patients with degenerative cervical spine conditions. New intervertebral implant products are being developed to improve fusion and stability while decreasing complications. This study assesses the effectiveness of Tritanium C (Tri-C) Anterior Cervical Cage (Stryker) in the treatment of degenerative disk disease (DDD) of the cervical spine compared with polyetheretherketone (PEEK) cages.

Methods: A retrospective cohort analysis was conducted using data prospectively collected from two institutions. Patients who underwent ACDFs for DDD using either the Tri-C cage or PEEK cage were identified. The patients' demographics, comorbidities, operative variables, and baseline patient-reported outcomes (PROs) were collected. PROs included the Neck Disability Index (NDI) and numeric rating scale (NRS) for neck and arm pain. The primary outcomes included 3- and 12-month PROs as well as the rates of 90-day readmission, 90-day reoperation, and perioperative complication. The radiographic outcomes included rates of subsidence, cage movement, and successful fusion within 12 months. Multivariate linear regression models were run to identify variables predictive of 12-month PROs.

Results: A total of 275 patients who underwent ACDF were included in this study and were divided into two groups: PEEK (n=213) and Tri-C (n=62). Both groups showed improvement in neck and arm pain and NDI postoperatively. When Tri-C and PEEK were compared, no significant differences were observed in the 3- or 12-month changes in neck or arm pain or NDI. Furthermore, there were no differences in the rates of 90-day readmission, 90-day reoperation, and perioperative complication. Regression analysis revealed that Tri-C vs. PEEK was not a significant predictor of any outcome.

Conclusions: Our results indicate that the use of porous titanium Tri-C cage during ACDFs is an effective method for managing cervical DDD in terms of PROs, perioperative morbidity, and radiologic parameters. No significant difference was observed in any clinical outcome between patients undergoing ACDF using the Tri-C cage and those in whom the PEEK cage was used.

Level of Evidence: III

Introduction: The association between postoperative patient-reported outcomes (PROs) and patient satisfaction remains poorly defined in patients undergoing surgery for thoracic myelopathy. This study aimed to investigate PROs and patient satisfaction following surgical intervention for thoracic myelopathy.

Methods: A prospective cohort of 133 patients who underwent surgery for thoracic myelopathy at 13 hospitals between April 2017 and August 2021 was enrolled. Patient demographics and perioperative complications were recorded. PROs were assessed using questionnaires administered preoperatively and 1 year postoperatively, including the EuroQol-5 dimension, physical and mental component summaries of the 12-item Short-Form Health Survey, Oswestry Disability Index, and numerical rating scales for low back, lower extremity, and plantar pain. Patients were categorized into two groups: satisfied (very satisfied, satisfied, and slightly satisfied) and dissatisfied (neither satisfied nor dissatisfied, slightly dissatisfied, dissatisfied, and very dissatisfied).

Results: The mean age of the patients was 66.5 years, comprising 87 men and 46 women. The most common diagnoses were ossification of the ligamentum flavum (48.8%) and thoracic spondylotic myelopathy (26.3%). Seventy-four (55.6%) and 59 (44.3%) patients underwent decompression surgery and underwent decompression with fusion, respectively. Eight patients required reoperation due to postoperative surgical site infection, hematoma, and insufficient decompression in four, three, and one patient. Ninety (67.7%) patients completed both the preoperative and postoperative PRO questionnaires, all of which demonstrated significant improvement. Among them, 58 (64.4%) and 32 (35.6%) reported satisfaction and dissatisfaction with their treatment, respectively. The satisfied group showed superior improvement in PROs than the dissatisfied group, although there were no significant differences in complication rates between the two groups.

Conclusions: The 64.4% satisfaction rate observed in patients undergoing surgery for thoracic myelopathy was lower than that reported in previous studies on cervical or lumbar spine surgery. The dissatisfied group exhibited significantly poorer quality of life (QOL) and higher pain scores than the satisfied group.

Introduction: Segmental spinal deformity results from vertebral compression fracture (VCF) and progressive collapse of the fractured vertebral body (VB). The VB stenting (VBS) system^® comprises a balloon-assisted, expandable, intrasomatic, metal stent that helps maintain the restored VB during balloon removal and cement injection, which minimizes cement leakage. We performed a prospective, multicenter, clinical trial of the VBS system in Japanese patients with acute VCF owing to primary osteoporosis.

Methods: Herein, 88 patients, 25 men and 63 women aged 77.4±8.3 years, with low back pain, numerical rating scale (NRS) score of ≥4, and mean VB compression percentage (VBCP) of <60% were enrolled. The primary endpoints were the VBCP restoration rate and reduction in low back pain 1 month and 7 days after VBS surgery, respectively. Secondary endpoints included changes in VBCP, NRS pain score, Beck index, kyphosis angle, and quality of life according to the short form 36 (v2) score. Safety was assessed as adverse events, device malfunctions, and new vertebral fractures.

Results: Overall, 70 patients completed the study. VBS surgery increased the restoration rates of anterior and midline VBCP by 31.7%±26.5% (lower 95% confidence intervals (CI): 26.8) and 31.8%±24.6% (lower 95% CI: 27.2), respectively, and the reduction in NRS pain score was −4.5±2.4 (upper 95% CI: −4.0). As these changes were greater than the predetermined primary endpoint values (20% for VBCP and −2 for NRS score), they were judged clinically significant; these changes were maintained throughout the 12-month follow-up (p<0.001). Likewise, significant improvement was observed in the Beck index, kyphosis angle, and quality of life score, which were maintained throughout the follow-up. There were three serious adverse events. New fractures occurred in 12 patients-all in the adjacent VB.

Conclusions: VBS surgery effectively restored the collapsed VB, relieved low back pain, and was tolerable in patients with acute osteoporotic VB fracture.

Introduction: We aimed to implement the enhanced recovery after surgery (ERAS) protocol for pediatric neuromuscular scoliosis (NMS) surgery and to examine the effectiveness of this program in this study.

Methods: Subjects were children with NMS who underwent scoliosis surgery at our department by a surgeon using a single posterior approach. A series of 27 cases before the introduction of ERAS and 27 cases during program stabilization were included in the study. Patient backgrounds did not show significant differences before and after introducing ERAS. Perioperative data, complications, length of hospital stay (LOS), and readmission within 90 days were investigated and statistically analyzed.

Results: When the pre- and post-ERAS induction groups were compared, no significant differences in anesthesia induction time (p=0.979), pelvic fixation (p=0.586), fusion levels (p=0.479), intraoperative hypothermia duration (p=0.154), end-of-surgery body temperature (p=0.197), operative time (p=0.18), postoperative main Cobb angle (p=0.959), main Cobb angle correction rate (p=0.91), postoperative spino-pelvic obliquity (SPO) (p=0.849), and SPO correction rate (p=0.267) were observed. However, significant differences in using V-flap technique (p=0.041), intraoperative blood loss (p=0.001), and LOS (p=0.001) were observed. Intraoperative blood loss was weakly correlated with LOS (p=0.432 and 0.001). No statistically significant difference existed between the V-flap method and LOS (p=0.265). Multiple regression analysis using LOS as the objective variable and ERAS protocols and intraoperative blood loss as explanatory variables revealed that the effect of ERAS on LOS was greater than that of intraoperative blood loss. No statistically significant differences in the readmission rates within 90 days were found.

Conclusions: After the introduction of ERAS, LOS decreased without an increase in complications or readmissions within 90 days.

Introduction: Postoperative spinal epidural hematoma (PSEH) is a severe complication of spinal surgery that necessitates accurate and timely diagnosis. This study aimed to assess the accuracy of ultrasonography as an alternative diagnostic tool for PSEH after microendoscopic laminotomy (MEL) for lumbar spinal stenosis, comparing it with magnetic resonance imaging (MRI).

Methods: A total of 65 patients who underwent MEL were evaluated using both ultrasound- and MRI-based classifications for PSEH. Intra- and interrater reliabilities were analyzed. Furthermore, ethical standards were strictly followed, with spine surgeons certified by the Japanese Orthopaedic Association performing evaluations.

Results: Among the 65 patients, 91 vertebral segments were assessed. The intra- and interrater agreements for PSEH classification were almost perfect for both ultrasound (κ=0.824 [95% confidence interval (CI) 0.729-0.918] and κ=0.810 [95% CI 0.712-0.909], respectively) and MRI (κ=0.839 [95% CI 0.748-0.931] and κ=0.853 [95% CI 0.764-0.942], respectively). The results showed high concordance between ultrasound- and MRI-based classifications, validating the reliability of ultrasound in postoperative PSEH evaluation.

Conclusions: This study presents a significant advancement by introducing ultrasound as a precise and practical alternative to MRI for PSEH evaluation. The comparable accuracy of ultrasound to MRI, rapid bedside assessments, and radiation-free nature make it valuable for routine postoperative evaluations. Despite the limitations related to specific surgical contexts and clinical outcome assessment, the clinical potential of ultrasound is evident. It offers clinicians a faster, cost-effective, and repeatable diagnostic option, potentially enhancing patient care. This study establishes the utility of ultrasound in evaluating postoperative spinal epidural hematomas after MEL. With high concordance to MRI, ultrasound emerges as a reliable, practical, and innovative tool, promising improved diagnostic efficiency and patient outcomes. Further studies should explore its clinical impact across diverse surgical scenarios.

Introduction: This study aimed to compare the outcomes of corrective fusion for adult spinal deformity (ASD) in older people using two different sagittal correction goals: the conventional formula of "pelvic incidence (PI) -lumbar lordosis (LL) mismatch <10°" and an undercorrection strategy based on the range of 10°≤PI-LL≤20°.

Methods: A total of 102 consecutive patients (11 male and 91 female patients; mean age, 72.0 years) aged above 65 years with scoliosis >20° or LL<20° who had undergone long-segment fusion from the lower thoracic spine to the pelvis for ASD and had been followed-up for a minimum of two years at our institution since March 2013 were included in this retrospective study. After excluding patients with PI-LL≤−10° on postoperative standing radiographs, the remaining patients were divided into two groups: 31 patients with 10°≤PI-LL≤20° (U group) and 63 patients with −10°<PI-LL<10° (M group). Radiological and clinical outcomes were compared between the groups.

Results: The incidence of proximal junctional kyphosis and mechanical failure was not significantly different between the groups (p=0.659 and 1.000, respectively). After excluding patients who underwent reoperation due to mechanical failure, there were no differences in the Oswestry Disability Index (ODI) and each domain of the Visual Analog Scale score, Scoliosis Research Society-22r patient questionnaire (SRS-22r), or the short form 36 health survey questionnaire at the final observation between the U (n=27) and M (n=57) groups. In addition, the non-inferiority and equivalence of the U group to the M group were demonstrated in all domains of the SRS-22r and ODI. Furthermore, the superiority of the U group was demonstrated by the functional domain of SRS-22r.

Conclusions: For the sagittal correction goal in corrective fusion surgery for ASD in the elderly, strict adherence to "PI-LL mismatch <10°" is not necessary and "PI-LL≤20°" may be acceptable.

Introduction: S1-L5 transdiscal screw fixation is a direct stabilization technique used for surgical treatment of high-grade (III-IV) L5-S1 spondylolisthesis. It has not been used for nonspondylolisthetic cases or in combination with an interbody cage (IC). This study aimed to develop a novel, direct S1-L5 sacrolumbar interbody fusion (SLIF) technique, a combination of IC and sacrolumbar transdiscal screw.

Methods: SLIF was tested in cadaveric, clinical, and finite element analysis settings. Three cadaveric lumbar spines were used to test the SLIF procedure before clinical application. Eight patients underwent the SLIF procedure. Clinical outcomes were evaluated by visual analog score for leg and back pain, short form 36, Oswestry disability index, and neurological examination. CT scans of the lumbar spine were used to assess the hardware placement and subsequent fusion. Finite element analysis was performed on a healthy human CT-based L5-S1 model. Intact segment, unilateral facetectomy and discectomy, SLIF, and transforaminal lumbar interbody fusion (TLIF) procedures were compared in terms of the range of motion (ROM), von Mises stress on hardware, and shear-induced directional deformity. Additionally, the same set of tests were conducted in an osteoporotic model.

Results: Excellent hardware placement was feasible in three cadavers and eight patients. Preoperative neurological deficits improved in all patients. Statistically significant improvements were obtained on all self-reported questionnaire scores. All patients developed solid, Bridwell grade I fusions. Biomechanical testing revealed similar outcomes for TLIF and SLIF regarding the ROM. However, the screw's von Mises stress and shear-induced directional deformity were low for SLIF of healthy and osteoporotic bone.

Conclusions: SLIF is a feasible, safe, and effective L5-S1 fusion option suitable for all clinical scenarios. It provides several biomechanical advantages, yielding excellent clinical outcomes.

Introduction: This study aimed to measure the intraocular pressure (IOP) of patients undergoing open surgery in the supine position (control group) and spine surgery in the prone position (spine group) to clarify IOP range and change by posture, determine the risk factors for increased IOP in the prone position, and reduce visual complications after surgery in the prone position.

Methods: A prospective cohort study was conducted in healthy adults (34-83 years of age) with an American Society of Anesthesiologists classification I/II. The spine group was examined for IOP, anterior chamber angle (ACA), and fundus findings the day prior to surgery. On the day of surgery, IOP measurements were taken at fixed time points: immediately after intubation; at 0.5, 1, and 2 h after intubation; at suture closure; and at the end of surgery in the control group. In the spine group, they were taken immediately after intubation; at 0.5, 1, and 2 h after prone position; at suture closure; and immediately and 5 min after returning to the supine position. The risk factors for increased IOP in the prone position were examined.

Results: The control group showed no significant changes in IOP within the normal range (<20 mmHg) during surgery. In the spine group, IOP was higher at each time point than immediately after intubation. IOP increased sharply above the normal range within 1 h after changing from the supine to the prone position and continued to gradually increase until suture closure. IOP decreased 5 min after the patient returned to the supine position. ACA, body mass index, blood loss, time in the prone position, and operative time were not risk factors for increased IOP in the prone position.

Conclusions: Patients were constantly exposed to above-normal IOP during prone spinal surgery. However, neither group reported visual impairment. No risk factors were identified for increased IOP in the prone position.