Assessing the Reproducibility of the Structured Abstracts Generated by ChatGPT and Bard Compared to Human-Written Abstracts in the Field of Spine Surgery: Comparative Analysis.

BACKGROUND: Due to recent advances in artificial intelligence (AI), language model applications can generate logical text output that is difficult to distinguish from human writing. ChatGPT (OpenAI) and Bard (subsequently rebranded as "Gemini"; Google AI) were developed using distinct approaches, but little has been studied about the difference in their capability to generate the abstract. The use of AI to write scientific abstracts in the field of spine surgery is the center of much debate and controversy. OBJECTIVE: The objective of this study is to assess the reproducibility of the structured abstracts generated by ChatGPT and Bard compared to human-written abstracts in the field of spine surgery. METHODS: In total, 60 abstracts dealing with spine sections were randomly selected from 7 reputable journals and used as ChatGPT and Bard input statements to generate abstracts based on supplied paper titles. A total of 174 abstracts, divided into human-written abstracts, ChatGPT-generated abstracts, and Bard-generated abstracts, were evaluated for compliance with the structured format of journal guidelines and consistency of content. The likelihood of plagiarism and AI output was assessed using the iThenticate and ZeroGPT programs, respectively. A total of 8 reviewers in the spinal field evaluated 30 randomly extracted abstracts to determine whether they were produced by AI or human authors. RESULTS: The proportion of abstracts that met journal formatting guidelines was greater among ChatGPT abstracts (34/60, 56.6%) compared with those generated by Bard (6/54, 11.1%; P<.001). However, a higher proportion of Bard abstracts (49/54, 90.7%) had word counts that met journal guidelines compared with ChatGPT abstracts (30/60, 50%; P<.001). The similarity index was significantly lower among ChatGPT-generated abstracts (20.7%) compared with Bard-generated abstracts (32.1%; P<.001). The AI-detection program predicted that 21.7% (13/60) of the human group, 63.3% (38/60) of the ChatGPT group, and 87% (47/54) of the Bard group were possibly generated by AI, with an area under the curve value of 0.863 (P<.001). The mean detection rate by human reviewers was 53.8% (SD 11.2%), achieving a sensitivity of 56.3% and a specificity of 48.4%. A total of 56.3% (63/112) of the actual human-written abstracts and 55.9% (62/128) of AI-generated abstracts were recognized as human-written and AI-generated by human reviewers, respectively. CONCLUSIONS: Both ChatGPT and Bard can be used to help write abstracts, but most AI-generated abstracts are currently considered unethical due to high plagiarism and AI-detection rates. ChatGPT-generated abstracts appear to be superior to Bard-generated abstracts in meeting journal formatting guidelines. Because humans are unable to accurately distinguish abstracts written by humans from those produced by AI programs, it is crucial to exercise special caution and examine the ethical boundaries of using AI programs, including ChatGPT and Bard.

Fundamental principle of adult spinal deformity.

The management of adult spinal deformity (ASD) requires a personalized, multidisciplinary approach. Effective treatment hinges on thorough assessment using advanced imaging to understand the severity and impact of the spinal curvature. This paper underscores the importance of tailoring treatment plans to individual patient factors such as age, health, and psychological well-being, weighing both surgical and non-surgical options.Non-surgical treatments like pain management and physical therapy are preferred initially. If surgery is necessary, candidate selection and the choice of surgical technique are crucial. Minimally invasive procedures and advanced technologies like robotics enhance precision and reduce risks.Postoperative care and continuous monitoring are essential to assess the success of the intervention and manage any complications. This comprehensive strategy aims to improve overall functionality and quality of life, ensuring that treatment addresses both the physical deformity and its broader impacts. (Presented at the 2010th Meeting, May 20, 2024).

Super-elderly, spinal surgery, evaluating the risks and benefits: a retrospective single-centre cohort study.

INTRODUCTION: An increasingly ageing population presents emerging healthcare challenges. Adequate clinical evaluation and understanding of outcome-predicting factors are integral to delivering safe spinal surgery to super-elderly patients. AIM: To evaluate spine surgery outcomes in patients aged 80 or above. METHODS: We retrospectively evaluated patients 80 years and above who underwent elective or emergency spinal surgery between 2017 and 2022. The Eurospine Surgery Classification (ESC) was used to classify operations into Large, Medium, and Small. We calculated and compared Clinical Frailty Scores (CFS) pre- and post-operatively. RESULTS: Two hundred forty-five patients met the inclusion criteria. Most were male (n = 145). The age range was 80 to 99 (mean 83.3). Most operations were elective (n = 151, 62%). In our cohort, 211, 22, 10,2 and 1 patients had degenerative, trauma, tumour, infective and vascular pathologies, respectively. According to the Eurospine classification, 201 (82.0%) had Minor spine surgery (63 emergently and 138 electively), 38 had Medium surgery (15.5% - 30 emergently and 8 electively), and 6 had Large surgery (2.4% - 1 emergently and 5 electively). 163 (66.5%) were discharged or under follow-up. There were 11 in-patient mortalities (4.5%). Outpatient mortality was 51 (20.8%), with the median time from surgery to death being 504.5 days, all the outpatient mortalities were neither non-spinal pathology nor spinal surgical related. CFS improved across the cohort, from 5 pre-operatively to 4 post-operatively (p < 0.001). CONCLUSION: Spine surgery in those over the 80s can be performed safely and improve their quality of life, as demonstrated by improvements in the CFS. Good patient selection and adequate pre-operative workup is essential, although it may not be possible in emergencies.

Determining the Optimal Dosage of Dexmedetomidine for Smooth Emergence in Older Patients Undergoing Spinal Surgery: A Study of 44 Cases.

BACKGROUND Emergence agitation, or delirium, occurs during early recovery from general anesthesia and involves disorientation, excitation, and uncontrolled physical movements. Dexmedetomidine is an alpha agonist that has sedative, anxiolytic, analgesic, and sympatholytic activities and is used as a continuous infusion to prevent emergence agitation. This study aimed to evaluate patients aged 65 years and older undergoing general anesthesia to determine the 90% effective dose (ED90) of dexmedetomidine continuous intraoperative infusion to prevent emergence agitation. MATERIAL AND METHODS We enrolled 44 patients aged 65 years and older undergoing spinal surgery under general anesthesia. Dexmedetomidine administration commenced 30 minutes before surgery completion, with a predetermined infusion dose (µg/kg/h), without a loading dose. The initial dose was 0.2 µg/kg/h, and subsequent step size was ±0.05 µg/kg/h. We tried to find ED90 of dexmedetomidine using the biased-coin design. Vital signs, extubation quality scores, extubation-related complications, and postoperative outcomes were monitored. RESULTS Dexmedetomidine ED90 for smooth emergence in older patients was 0.34 µg/kg/h. Peri-extubation vital signs remained within 20% of baseline values, without requiring pharmacological intervention. No hypoxia, hypoventilation, or post-extubation agitation occurred. In the recovery room, 1 patient briefly exhibited excitement but quickly calmed. Nine patients initially unresponsive in the recovery room fully awoke and were promptly discharged. CONCLUSIONS For older patients who are vulnerable to adverse effects of anesthetics and opioids, dexmedetomidine enables gentle awakening without adverse vital sign changes, respiratory depression, excessive sedation, or emergence agitation (ED90=0.34 µg/kg/h). Further studies should involve a larger patient cohort, considering diverse medical conditions in older individuals.

Effects of lower limb length discrepancy on spinopelvic compensation following total hip arthroplasty in patients with developmental dysplasia of the hip.

BACKGROUND: Limited research has examined the impact of lower limb length discrepancy (LLLD) alteration on spinopelvic compensation in individuals with developmental dysplasia of the hip (DDH). This study aimed to investigate the effects of LLLD on spinopelvic compensation following total hip arthroplasty (THA) and elucidate the complex biomechanical adaptations in the spinopelvic structures. METHODS: A retrospective review of DDH patients undergoing THA from January 2014 to December 2021 categorized individuals with Crowe type I and II into the low dislocation group (LDG, n = 94) and those with Crowe type III and IV into the high dislocation group (HDG, n = 43). Demographic data, as well as preoperative, postoperative, and last follow-up imaging data, including lower limb length (LLL), sacral obliquity (SO), iliac obliquity (IO), hip obliquity (HO), Cobb angle, apical vertebral translation (AVT), and coronal decompensation (CD), were collected for analysis. RESULTS: Patients in the LDG had a significantly higher surgical age and shorter disease duration (P<0.05). In LDG, patients exhibited substantial postoperative reductions in LLLD, SO, IO, and HO (P<0.05), while Cobb Angle, AVT, and CD showed no statistically significant changes (P>0.05). The variation in LLLD correlated significantly with the variations in SO, IO, and HO (P<0.05). Postoperative outcomes in the HDG demonstrated marked decreases in LLLD, SO, IO, HO, and CD (P<0.05), with no significant change in Cobb angle and AVT (P>0.05). The variation in LLLD correlated significantly with the variations in SO, IO, HO, and CD (P<0.05). CONCLUSIONS: THA effectively reduces LLLD in patients with DDH, and the variation in LLLD correlates meaningfully with the recovery of spinopelvic compensatory mechanisms.

Do we really apply evidence-based-recommendations to spine surgery? Results of an international survey.

OBJECTIVE: This international survey investigated Evidence-Based Medicine (EBM) in spine surgery by measuring its acceptance among spine surgeons. It assessed their understanding of EBM and how they apply it in practice by analyzing responses to various clinical scenarios.. MATERIALS AND METHODS: Following the CHERRIES guidelines, an e-survey was distributed to multiple social media forums for neurosurgeons and orthopedic surgeons on Facebook, LinkedIn, and Telegram and circulated further through email via the authors' network. Three hundred participants from Africa, Asia, Europe, North America, and Oceania completed the survey. RESULTS: Our study revealed that 67.7% (n = 203) of respondents used EBM in their practice, and 97.3% (n = 292) believed training in research methodology and EBM was necessary for the practice of spine surgery. Despite this endorsement of using EBM in spine surgery, we observed varied responses to how EBM is applied in practice based on example scenarios. The responders who had additional training tended to obey EBM guidelines more than those who had no additional training. Most surgeons responded as always or sometimes prescribing methylprednisolone to patients with acute spinal cord injury. Other significant differences were identified between geographical regions, training, practice settings, and other factors. CONCLUSIONS: Most respondents used EBM in practice and believed training in research methodology and EBM is necessary for spine surgery; however, there were significant variations on how to use them per case. Thus, the appropriate application of EBM in clinical settings for spinal surgery must be further studied.

Opioid-free versus opioid-based anesthesia in major spine surgery: a prospective, randomized, controlled clinical trial.

BACKGROUND: Major spine surgery is associated with severe postoperative pain and increased opioid consumption. Opioid-free anesthesia (OFA) is thought to provide adequate intraoperative analgesia with reduced postoperative opioid consumption. The aim of this study is to compare the impact of intraoperative OFA approach to the conventional opioid-based anesthesia (OBA) on postoperative pain, opioid consumption, and related side effects in patients undergoing multilevel spinal fusion surgery. METHODS: Forty-eight patients undergoing elective major spine surgery were randomly allocated to either receive intraoperative dexmedetomidine and lidocaine (OFA group) or fentanyl during induction and intraoperative remifentanil (OBA group). All patients received intraoperative sevoflurane, propofol, rocuronium, ketamine, dexamethasone, ondansetron and postoperative paracetamol and patient-controlled analgesia device set to deliver intravenous morphine for 48 hours after surgery. Postoperative pain was measured using numerical rating scale. Opioid side effects were documented, when present. RESULTS: OFA group required less morphine in the first 24 hours post-surgery (17.28±12.25 mg versus 27.96±19.75 mg, P<0.05). The incidence of postoperative nausea and vomiting (PONV) was significantly lower in the OFA group. More patients in the OFA group required antihypertensive medications compared to patients in the OBA group (P<0.05). In the post anesthesia care unit, OFA patients had a significantly longer stay than OBA patients (114.1±49.33 min versus 89.96±30.71 min, P<0.05). CONCLUSIONS: OFA can be an alternative to OBA in patients undergoing multilevel spine fusion surgery. OFA reduces opioids consumption in the first 24 hours and PONV.

Navigating challenges in spine surgery in Nigeria: the current state and strategies for advancing spine care.

The provision of specialized spine care in Nigeria presents a pressing challenge amid limited resources and geographical disparities. This correspondence offers a comprehensive roadmap for improving spine surgery and care within the country. We examine the current state of spinal health infrastructure, highlighting barriers such as limited access to specialists and facilities, particularly in rural areas, and financial constraints for patients. Innovations in spinal treatment, including the adoption of minimally invasive techniques and advancements in surgical modalities, are discussed alongside persistent challenges such as disparities in access and equipment costs. Training and education of spine surgeons emerge as critical areas requiring attention, with a shortage of qualified professionals exacerbated by inadequate training programs and resource constraints. We advocate for fostering local and international collaborations to address these gaps, emphasizing the role of partnerships in capacity building and knowledge exchange. Additionally, we explore the potential of public-private partnerships and investments to enhance the Nigerian spine healthcare system, calling for strategic initiatives to modernize infrastructure and improve accessibility. Finally, we propose a strategic blueprint encompassing infrastructure enhancement, training programs, research initiatives, policy advocacy, and public awareness campaigns. Through concerted efforts from local stakeholders and international partners, we envision a future where spine care in Nigeria is comprehensive, accessible, and of high quality, leading to improved health outcomes and a higher quality of life for those affected by spinal conditions.

Effect of desflurane anesthesia on flash visual evoked potential monitoring in patients undergoing spine surgery: study protocol for a randomized controlled trial.

BACKGROUND: Flash visual evoked potentials (FVEPs) are a reliable method for protecting visual function during spine surgery in prone position. However, the popularization and application of FVEPs remain limited due to the unclear influence of various anesthetics on FVEPs. Exploring the effects of anesthetic drugs on FVEP and establishing appropriate anesthesia maintenance methods are particularly important for promoting and applying FVEP. According to the conventional concept, inhaled narcotic drugs significantly affect the success of FVEP monitoring, FVEP extraction, and interpretation. Nonetheless, our previous study demonstrated that sevoflurane-propofol balanced anesthesia was a practicable regimen for FVEPs. Desflurane is widely used in general anesthesia for its rapid recovery properties. As the effect of desflurane on FVEP remains unclear, this trial will investigate the effect of different inhaled concentrations of desflurane anesthesia on amplitude of FVEPs during spine surgery, aiming to identify more feasible anesthesia schemes for the clinical application of FVEP. METHODS/ DESIGN: A total of 70 patients undergoing elective spinal surgery will be enrolled in this prospective, randomized controlled, open-label, patient-assessor-blinded, superiority trial and randomly assigned to the low inhaled concentration of desflurane group (LD group) maintained with desflurane-propofolremifentanil-balanced anesthesia or high inhaled concentration of desflurane group (HD group) maintained with desflurane-remifentanil anesthesia maintenance group at a ratio of 1:1. All patients will be monitored for intraoperative FVEPs, and the baseline will be measured half an hour after induction under total intravenous anesthesia (TIVA). After that, patients will receive 0.5 minimum alveolar concentration (MAC) of desflurane combined with propofol and remifentanil for anesthesia maintenance in the LD group, while 0.7-1.0 MAC of desflurane and remifentanil will be maintained in the HD group. The primary outcome is the N75-P100 amplitude 1 h after the induction of anesthesia. We intend to use the dual measure evaluation, dual data entry, and statistical analysis by double trained assessors to ensure the reliability and accuracy of the results. DISCUSSION: This randomized controlled trial aims to explore the superiority effect of low inhaled concentration of desflurane combined with propofolremifentanil-balanced anesthesia versus high inhaled concentration of desflurane combined with remifentanil anesthesia on amplitude of FVEPs. The study is meant to be published in a peer-reviewed journal and might guide the anesthetic regimen for FVEPs. The conclusion is expected to provide high-quality evidence for the effect of desflurane on FVEPs and aim to explore more feasible anesthesia schemes for the clinical application of FVEPs and visual function protection. TRIAL REGISTRATION: This study was registered on clinicaltrials.gov on July 15, 2022. CLINICALTRIALS: gov Identifier: NCT05465330.

Implementing a nurse-led prehabilitation program for patients undergoing spinal surgery.

ABSTRACT: Prehabilitation, or "prehab," helps patients optimize strength, function, and nutrition before surgery. This evidence-based practice project presents strategies for implementing a prehab program to prepare patients for spinal surgery. Nurses play an integral role in educating patients preoperatively about the myriad lifestyle changes associated with spinal surgery.

Instrumental Evaluation of the Effects of Vertebral Consolidation Surgery on Trunk Muscle Activations and Co-Activations in Patients with Multiple Myeloma: Preliminary Results.

Multiple myeloma (MM) patients complain of pain and stiffness limiting motility. To determine if patients can benefit from vertebroplasty, we assessed muscle activation and co-activation before and after surgery. Five patients with MM and five healthy controls performed sitting-to-standing and lifting tasks. Patients performed the task before and one month after surgery. Surface electromyography (sEMG) was recorded bilaterally over the erector spinae longissimus and rectus abdominis superior muscles to evaluate the trunk muscle activation and co-activation and their mean, maximum, and full width at half maximum were evaluated. Statistical analyses were performed to compare MM patients before and after the surgery, MM and healthy controls and to investigate any correlations between the muscle's parameters and the severity of pain in patients. The results reveal increased activations and co-activations after vertebroplasty as well as in comparison with healthy controls suggesting how MM patients try to control the trunk before and after vertebroplasty surgery. The findings confirm the beneficial effects of vertebral consolidation on the pain experienced by the patient, despite an overall increase in trunk muscle activation and co-activation. Therefore, it is important to provide patients with rehabilitation treatment early after surgery to facilitate the CNS to correctly stabilize the spine without overloading it with excessive co-activations.

Magnesium malate-modified calcium phosphate bone cement promotes the repair of vertebral bone defects in minipigs via regulating CGRP.

Active artificial bone substitutes are crucial in bone repair and reconstruction. Calcium phosphate bone cement (CPC) is known for its biocompatibility, degradability, and ability to fill various shaped bone defects. However, its low osteoinductive capacity limits bone regeneration applications. Effectively integrating osteoinductive magnesium ions with CPC remains a challenge. Herein, we developed magnesium malate-modified CPC (MCPC). Incorporating 5% magnesium malate significantly enhances the compressive strength of CPC to (6.18 ± 0.49) MPa, reduces setting time and improves disintegration resistance. In vitro, MCPC steadily releases magnesium ions, promoting the proliferation of MC3T3-E1 cells without causing significant apoptosis, proving its biocompatibility. Molecularly, magnesium malate prompts macrophages to release prostaglandin E2 (PGE2) and synergistically stimulates dorsal root ganglion (DRG) neurons to synthesize and release calcitonin gene-related peptide (CGRP). The CGRP released by DRG neurons enhances the expression of the key osteogenic transcription factor Runt-related transcription factor-2 (RUNX2) in MC3T3-E1 cells, promoting osteogenesis. In vivo experiments using minipig vertebral bone defect model showed MCPC significantly increases the bone volume fraction, bone density, new bone formation, and proportion of mature bone in the defect area compared to CPC. Additionally, MCPC group exhibited significantly higher levels of osteogenesis and angiogenesis markers compared to CPC group, with no inflammation or necrosis observed in the hearts, livers, or kidneys, indicating its good biocompatibility. In conclusion, MCPC participates in the repair of bone defects in the complex post-fracture microenvironment through interactions among macrophages, DRG neurons, and osteoblasts. This demonstrates its significant potential for clinical application in bone defect repair.

Enhanced Recovery After Surgery (ERAS) Spine Pathways and the Role of Perioperative Checklists.

Enhanced recovery after surgery (ERAS) proposes a multimodal, evidence-based approach to perioperative care. ERAS pathways have been shown to help reduce complications, hospital length of stay (LOS), 30-day readmission rates, pain scores, and ultimately surgical costs, while improving patient satisfaction scores and outcomes in multiple surgical subspecialties [1-6]. Numerous specialties have implemented ERAS programs across the globe, providing a foundation for spine surgeons to begin the process themselves. Over the last few years, a significant number of papers have been addressing ERAS pathways for spinal surgery [7-19]. The majority have addressed the lumbar spine [9, 20-26]. The number of cervical ERAS pathways has been limited [27-29]. Many spine programs have begun the implementation of ERAS pathways, incorporating principles and interventions to various spine surgical procedures. Although differences in implementation across programs exist, there are a few common elements that promote a successful enhanced recovery approach [11, 16, 23, 25, 30-33]. All spinal ERAS pathways have three major elements, which are preoperative, perioperative, and postoperative phases. Within these phases some common elements include preoperative and intraoperative surgical checklists. Intraoperative checklist in addition to the "surgical time out" has been integrated into the workflow of most hospitals doing surgeries and have become a standard of care. The surgical checklist is designed to help reduce surgical errors and prevent wrong site/patient surgeries. Several surgical checklists have been developed throughout the years. Despite these safety protocols wrong site/level and other surgical errors continue to occur. Many cases of wrong level spine surgery (WLSS) still occur even when intraoperative imaging is performed [34, 35]. One survey reported that about 50% of spine surgeons have performed at least one WLSS during their career [36, 37]. Another survey reported that 36% of spine surgeons had performed at least one WLSS that was not recognized intraoperatively [38]. On a similar account, about 30% of spine surgery fellows have experienced wrong-site surgery [39]. From raw incidence rates, WLSS may seem rare, but these surveys show that the experience of WLSS is rather common among spine surgeons. WLSS is not yet a "never event." This may be due to poor quality of the intraoperative images, hindering subsequent level identification [34, 35, 38, 40]. Errors in interpretation of the imaging may also occur, including inconsistency in numbering vertebrae, inconsistency in landmark usage for level counting, and problems with numbering vertebrae due to lumbosacral transitional vertebrae (LSTV) and other anatomical variants [34, 38, 41-43]. This chapter will describe a framework for the development and implementation of ERAS pathway for patients undergoing spine surgery. In addition, we will propose preoperative imaging guidelines and a comprehensive spine surgical checklist to incorporate into the perioperative phase to help reduce further surgical errors and WLSS.

Clinical applications of AI-prediction tools in spine surgery: a narrative review.

Spine surgery has grown into a wide, complex field encompassing trauma surgery to deformity to tumours. Artificial intelligence (AI) based technology has been particularly useful in improving imaging-reporting and detection of predictive patterns. The purpose of this narrative review is to present practical approaches towards implementing upcoming AI spine research for clinicians to help improve practices, clinical throughput, and surgical decision-making.

[Small tidal volume hyperventilation relieves intraocular and intracranial pressure elevation in prone spinal surgery: a randomized controlled trial].

OBJECTIVE: To investigate the effects of different ventilation strategies on intraocular pressure (IOP) and intracranial pressure in patients undergoing spinal surgery in the prone position under general anesthesia. METHODS: Seventy-two patients undergoing prone spinal surgery under general anesthesia between November, 2022 and June, 2023 were equally randomized into two groups to receive routine ventilation (with Vt of 8mL/kg, Fr of 12-15/min, and etCO2 maintained at 35-40 mmHg) or small tidal volume hyperventilation (Vt of 6 mL/kg, Fr of18-20/min, and etCO2 maintained at 30-35 mmHg) during the surgery. IOP of both eyes (measured with a handheld tonometer), optic nerve sheath diameter (ONSD; measured at 3 mm behind the eyeball with bedside real-time ultrasound), circulatory and respiratory parameters of the patients were recorded before anesthesia (T0), immediately after anesthesia induction (T1), immediately after prone positioning (T2), at 2 h during operation (T3), immediately after supine positioning after surgery (T4) and 30 min after the operation (T5). RESULTS: Compared with those at T1, IOP and ONSD in both groups increased significantly at T3 and T4(P < 0.05). IOP was significantly lower in hyperventilation group than in routine ventilation group at T3 and T4(P < 0.05), and ONSD was significantly lower in hyperventilation group at T4(P < 0.05). IOP was positively correlated with the length of operative time (r=0.779, P < 0.001) and inversely with intraoperative etCO2 at T3(r=-0.248, P < 0.001) and T4(r=-0.251, P < 0.001).ONSD was correlated only with operation time (r=0.561, P < 0.05) and not with IOP (r=0.178, P>0.05 at T3; r=0.165, P>0.05 at T4). CONCLUSION: Small tidal volume hyperventilation can relieve the increase of IOP and ONSD during prone spinal surgery under general anesthesia.

Effect of Insertional Direction of Pedicle Screw on Screw Loosening: A Biomechanical Study on Synthetic Bone Vertebra under a Physiology-like Load.

OBJECTIVES: It is now understood that pedicle screw loosening at the implant-bone interface can lead to poor screw-bone interface purchase and decreased fixation stability. Previous biomechanical tests used cadaveric vertebrae and pull-out or torque loads to assess the effect of the insertional direction of pedicle screws on screw loosening. However, these tests faced challenges in matching biomechanical differences among specimens and simulating in vivo loads applied on pedicle screws. This study aimed to evaluate the effect of the insertional direction of pedicle screws on screw loosening using tension-compression-bending loads and synthetic bone vertebrae. METHODS: Polyaxial pedicle screws were inserted into nine synthetic bone vertebrae in three directions (three samples per group): cranial, parallel, and caudad (-10°, 0°, +10° of the pedicle screw rod to the upper plane of the vertebra, respectively). Pedicle screws in the vertebrae were loaded using a polyethylene block connected to a material testing machine. Tension-compression-bending loads (100N-250N) with 30,000 cycles were applied to the pedicle screws, and displacements were recorded and then cycle-displacement curve was drawn based on cycle number. Micro-CT scans were performed on the vertebrae after removing the pedicle screws to obtain images of the screw hole, and the screw hole volume was measured using imaging analysis software. Direct comparison of displacements was conducted via cycle-displacement curve. Screw hole volume was analyzed using analysis of variance. The correlation between the displacement, screw hole volume and the direction of pedicle screw was assessed by Spearman correlation analysis. RESULTS: The smallest displacements were observed in the caudad group, followed by the parallel and cranial groups. The caudad group had the smallest screw hole volume (p < 0.001 and p = 0.009 compared to the cranial and parallel groups, respectively), while the volume in the parallel group was greater than that in the cranial group (p = 0.003). Correlation analysis revealed that the insertional direction of the pedicle screw was associated with the displacement (p = -0.949, p < 0.001) and screw hole volume (p = -0.944, p < 0.001). CONCLUSION: Strong correlations were found between the insertional direction of the pedicle screw and relevant parameters, including displacement and screw hole volume. Pedicle screw insertion in the caudad direction resulted in the least pedicle screw loosening.