Search Results (79)

Pedicle screw fixation is a critical technique for stabilizing lumbar fractures in canines, yet the biomechanical implications of insertion angles remain underexplored. This study aims to identify optimal screw trajectories by analyzing stress distribution and deformation patterns in beagle lumbar segments (L6-L7) using finite element analysis (FEA). A 3D finite element model was reconstructed from CT scans of a healthy beagle, incorporating cortical/cancellous bone, intervertebral disks, and cartilage. Pedicle screws (2.4 mm diameter, 22 mm length) were virtually implanted at angles ranging from 45° to 65°. A 10 N vertical load simulated standing conditions. Equivalent stress and total deformation were evaluated under static loading. The equivalent stress occurred at screw–rod junctions, with maxima at 50° (11.73 MPa) and minima at 58° (3.25 MPa). Total deformation ranged from 0.0033 to 0.0064 mm, with the highest at 55° and the lowest at 54°. The 58° insertion angle demonstrated optimal biomechanical stability with minimal stress concentration, with 56–60° as a biomechanically favorable range for pedicle screw fixation in canine lumbar fractures, balancing stress distribution and deformation control. Future studies should validate these findings in multi-level models and clinical settings. Full article

The traditional bilateral pedicle screw system has been used for the treatment of various lumbar spine conditions including advanced degenerative disc disease. However, there is an ongoing need to develop more effective and less invasive techniques. The purpose of this study was to compare the traditional bilateral pedicle screw system (BPSS) with the novel reverse transdiscal screw system (RTSS) for lumbar disc degenerative disease. A 3D solid lumbar L1–L5 spine model was developed and validated based on a human CT scan. Fusions were simulated at L3–L4. The first scenario comprised a transforaminal lumbar interbody cage in combination with the bilateral pedicle screw-rod system (BPSS-TLIF). In the second scenario, the same TLIF cage was combined with reverse L3–L4 transdiscal screws (RTSS-TLIF). Testing parameters included range of motion (ROM) in three orthogonal axes, hardware (cage and screw) stress, and shear load resistance. The ROM of the surgical model was reduced by approximately 90% compared to the intact model at the fused level. The RTSS model demonstrated less ROM compared to the BPSS model at the fused level for all loading conditions. Overall, the RTSS model exhibited lower stress on both screws and cage compared with the BPSS model in all biomechanical testing conditions. The RTSS model also exhibited higher anterior and posterior shear load resistance than the BPSS model. In conclusion, the RTSS model proved superior to the BPSS model in all respects. These findings indicate that the RTSS could serve as a feasible option for patients undergoing lumbar fusion, especially for adjacent segment disease, potentially enhancing surgical outcomes for disc degeneration. Full article

Background and Objectives: Angular modifications in the physiological curvatures of the spine have been associated with spinal dysfunction and altered biomechanics, which may contribute to musculoskeletal complaints. The main objective of this experimental study was to investigate the association between lumbar lordosis and thoracic kyphosis angles and muscle activations during three different lower back exercises. Materials and Methods: Participants were divided into a hyperlordotic lumbar angle group—with increased thoracic kyphosis (n = 11)—and a normal lordotic lumbar thoracic angle group (n = 11). Thoracolumbar muscular activities during three different exercises were measured by surface electromyography. Results: Muscular activity was less in almost all exercises (except iliocostalis lumborum-pars lumborum) in the hyperlordotic lumbar angle/increased thoracic kyphosis group (p < 0.05). The unstable superman exercise was the exercise that produced the most muscular activity in both groups (p < 0.05). Conclusions: The study analyzed the association between lumbar lordosis, increased thoracic kyphosis, and muscle activations during specific lower back exercises. These findings highlight the relationship between spinal alignment and muscular responses during functional tasks, which may inform future biomechanical research or rehabilitation strategies. Full article

Prolonged periods of standing are linked to low back pain (LBP). Evaluating lumbar spine biomechanics in real-world contexts can provide novel insights into these links. This study aimed to determine if standing behaviour can be quantified, in individuals with LBP, in real-world environments. A three-stage design was used, (i) Verification of a bespoke algorithm characterising lumbar standing behaviour, (ii) Day-long assessment of standing behaviours of individuals with posture-related low back discomfort, and (iii) Case study application to individuals with clinical LBP. Analysis of standing posture across time included variability, fidgeting, and amplitude probability distribution function analysis. The study demonstrated that accelerometers are a valid method for extracting standing posture from everyday activity data. There was a wide variety of postures throughout the day in people with posture-related low back discomfort and people with clinical LBP. Frequency profiles ranged from slightly flexed to slightly extended postures, with skewed bell-shaped distributions common. Postural variability ranged from 3.4° to 7.7°, and fidgeting from 1.0° to 3.0°. This work presents a validated accelerometer-based method to capture, identify, and quantify real-world lumbar standing postures. The distinct characteristics of people with low back discomfort or pain highlight the importance of individualised approaches. Full article

Objectives: This study’s purpose is to investigate the lumbar biomechanical effects of unilateral partial facetectomy (UPF) of different facet joint (FJ) portions under percutaneous endoscopy. Methods: Forty fresh calf spine models were used to simulate UPF under a physiological load performed through three commonly used needle insertion points (IPs): (1) The apex of the superior FJ (as the first IP); (2) The midpoint of the ventral side of the superior FJ (as the second IP); (3) The lowest point of the ventral side of the superior FJ (as the third IP). The range of motion (ROM) and the L4/5 intradiscal maximum pressure (IMP) were measured and analyzed under a physiological load in all models during flexion, extension, left–right lateral flexion, and left–right axial rotation. Results: When UPF was performed through the second IP, the ROM of the lumbar spine and the L4/5 IMP in the calf spine models were not statistically different from the intact calf spine model. Conclusions: UPF through the second IP resulted in a minimal impact on the biomechanics of the lumbar spine. Thus, it might be considered the most appropriate IP for UPF. Full article

The interspinous process device (IPD) has emerged as a viable alternative for managing lumbar degenerative pathologies. Nevertheless, limited research exists regarding mechanical failure modes including device failure and spinous process fracture. This study developed a novel IPD (IPD-NEW) and systematically evaluated its biomechanical characteristics through finite element (FE) analysis and in vitro cadaveric biomechanical testing. Six human L1–L5 lumbar specimens were subjected to mechanical testing under four experimental conditions: (1) Intact spine (control); (2) L3–L4 implanted with IPD-NEW; (3) L3–L4 implanted with Wallis device; (4) L3–L4 implanted with Coflex device. Segmental range of motion (ROM) was quantified across all test conditions. A validated L1–L5 finite element model was subsequently employed to assess biomechanical responses under both static and vertical vibration loading regimes. Comparative analysis revealed that IPD-NEW demonstrated comparable segmental ROM to the Wallis device while exhibiting lower rigidity than the Coflex implant. The novel design effectively preserved physiological spinal mobility while enhancing load distribution capacity. IPD-NEW demonstrated notable reductions in facet joint forces, device stress concentrations, and spinous process loading compared to conventional implants, particularly under vibrational loading conditions. These findings suggest that IPD-NEW may mitigate risks associated with facetogenic pain, device failure, and spinous process fracture through optimized load redistribution. Full article

Surgical management of adolescent idiopathic scoliosis [AIS] is a complex undertaking with the primary goals to correct the deformity, maintain sagittal balance, preserve pulmonary function, maximize postoperative function, and improve or at least not harm the function of the lumbar spine. The evolution of surgical techniques for AIS has been remarkable, transitioning from rudimentary methods of spinal correction to highly refined, biomechanically sound procedures. Modern techniques incorporate advanced three-dimensional correction strategies, often leveraging pedicle screw constructs, which provide superior rotational control of the vertebral column. A number of surgical techniques have been described in the literature, each having its own pros and cons. This narrative review provides a detailed analysis of the contemporary surgical techniques used in the treatment of patients with AIS. Full article

(1) Cage subsidence in spine surgery is a frequent clinical challenge. This study aimed to assess a novel screw augmentation technique for Transforaminal Lumbar Interbody Fusion in cadavers of reduced bone mineral density (BMD). (2) Forty human lumbar vertebrae (BMD 84.2 ± 24.4 mgHA/cm³, range 51–119 mgHA/cm³) were assigned to two groups: augmenting screw group and control group. The augmentation technique comprised placement of two additional subcortical screws. Ten constructs per group were loaded with a quasi-static load-to-failure protocol and other ten were cyclically loaded. Failure modes were documented. (3) During the quasi-static load-to-failure testing, the augmenting screw technique showed a significantly higher failure load (1426.0 ± 863.6 N) versus the conventional technique in the control group (682.2 ± 174.5 N, p = 0.032). Cyclic loading revealed higher number of cycles and corresponding load until reaching 5 mm subsidence and significantly higher number of cycles and corresponding load until reaching 10 mm subsidence for the augmenting screw technique (9645 ± 3050; 1164.5 ± 305.0 N) versus the conventional technique in the control group (5395 ± 2340; 739.5 ± 234.0 N, p < 0.05). Failure modes were different and showed bending of the augmenting screws, followed by cut-out. (4) The investigated augmenting screw technique demonstrated higher failure loads and cycles to failure against cage subsidence compared to conventional cage placement. Failure modes were different between the two techniques and may lead to a different kind of complications. Full article

Background/Objectives: Additional lateral fixation is a method with the potential to redistribute cage loading during oblique lumbar interbody fusion (OLIF). However, its biomechanical effects remain poorly understood. This study aimed to compare the mechanical responses of the lumbar spine following OLIF, both with and without additional lateral fixation, using a finite element (FE) analysis. Methods: An FE lumbar model with an OLIF cage at the L4–L5 levels was developed. A lateral fixation system comprising screws and a rod was incorporated to redistribute the cage loading and enhance spinal stability. Two OLIF cage positions—centered and at an oblique angle—were compared. Results: The additional lateral fixation reduced cage loading by 70% (409 to 123 N) and 72% (411 to 114 N) for the centered and oblique cage positions, respectively. Without lateral fixation, the peak equivalent stress on the cage during extension increased threefold (66 to 198 MPa) for the oblique position compared with that for the centered position. Conclusions: An additional lateral screw–rod fixation system is suggested as a complementary approach to the OLIF technique to mitigate endplate loading and pressure. Full article

Knowledge of realistic loads is crucial in the engineering design process of medical devices and for assessing their interaction with the spinal system. Depending on the type of modeling, current numerical spine models generally either neglect the active musculature or oversimplify the passive structural function of the spine. However, the internal loading conditions of the spine are complex and greatly influenced by muscle forces. It is often unclear whether the assumptions made provide realistic results. To improve the prediction of realistic loading conditions in both conservative and surgical treatments, we modified a previously validated forward dynamic musculoskeletal model of the intact lumbosacral spine with a muscle-driven approach in three scenarios. These exploratory treatment scenarios included an extensible lumbar orthosis and spinal instrumentations. The latter comprised bisegmental internal spinal fixation, as well as monosegmental lumbar fusion using an expandable interbody cage with supplementary posterior fixation. The biomechanical model responses, including internal loads on spinal instrumentation, influences on adjacent segments, and effects on abdominal soft tissue, correlated closely with available in vivo data. The muscle forces contributing to spinal movement and stabilization were also reliably predicted. This new type of modeling enables the biomechanical study of the interactions between active and passive spinal structures and technical systems. It is, therefore, preferable in the design of medical devices and for more realistically assessing treatment outcomes. Full article

Swimming is a widely practiced sport with significant physical demands, placing athletes at a considerable risk of injury, particularly in the shoulder, due to repetitive high-intensity movements. The aim of this systematic review was to analyze the patterns and frequency of injuries associated with swimming. Methods: A systematic search of the Web of Science, PubMed, Scopus, and SportDiscus databases identified nine relevant studies. Results: The findings revealed a higher incidence of injuries in female swimmers compared to males, with the shoulder being the most frequently affected joint. This disparity is partially attributed to the Female Athlete Triad, a syndrome characterized by low energy availability, menstrual dysfunction, and poor bone health, which increases injury susceptibility. Other commonly affected regions include the knee, often associated with the biomechanical demands of breaststroke, and the lumbar spine, which is impacted by degenerative changes resulting from high training volumes. However, variability in the injury measurement protocols across studies limits their comparability and highlights the need for standardized methods. Conclusions: Based on these findings, professionals in the field can identify injury patterns to enhance diagnosis and treatment, design personalized prevention programs, implement early interventions, and innovate equipment and training methods to improve swimmer safety and performance. Full article

(1) Background: The exploration of various machine learning (ML) algorithms for classifying the state of Lumbar Intervertebral Discs (IVD) in orthopedic patients is the focus of this study. The classification is based on six key biomechanical features of the pelvis and lumbar spine. Although previous research has demonstrated the effectiveness of ML models in diagnosing IVD pathology using imaging modalities, there is a scarcity of studies using biomechanical features. (2) Methods: The study utilizes a dataset that encompasses two classification tasks. The first task classifies patients into Normal and Abnormal based on their IVDs (2C). The second task further classifies patients into three groups: Normal, Disc Hernia, and Spondylolisthesis (3C). The performance of various ML models, including decision trees, support vector machines, and neural networks, is evaluated using metrics such as accuracy, AUC, recall, precision, F1, Kappa, and MCC. These models are trained on two open-source datasets, using the PyCaret library in Python. (3) Results: The findings suggest that an ensemble of Random Forest and Logistic Regression models performs best for the 2C classification, while the Extra Trees classifier performs best for the 3C classification. The models demonstrate an accuracy of up to 90.83% and a precision of up to 91.86%, highlighting the effectiveness of ML models in diagnosing IVD pathology. The analysis of the weight of different biomechanical features in the decision-making processes of the models provides insights into the biomechanical changes involved in the pathogenesis of Lumbar IVD abnormalities. (4) Conclusions: This research contributes to the ongoing efforts to leverage data-driven ML models in improving patient outcomes in orthopedic care. The effectiveness of the models for both diagnosis and furthering understanding of Lumbar IVD herniations and spondylolisthesis is outlined. The limitations of AI use in clinical settings are discussed, and areas for future improvement to create more accurate and informative models are suggested. Full article

Background: Chronic lumbopelvic pain is often linked to sacroiliac joint dysfunction, where the joint’s complex structure and biomechanics complicate diagnosis and treatment. Variability in load distribution and ligament stabilization within the pelvic ring further contributes to challenges in managing this condition. This study aims to develop a finite element model of the “lumbar spine–sacrum–pelvis” system to analyze the effects of lumbar lordosis, pelvic tilt, and asymmetrical articular gaps on stress and strain in the sacroiliac joint. Methods: A three-dimensional model was constructed using CT and MRI data, including key stabilizing ligaments. Sacral slope angles of 30°, 60°, and 85° were used to simulate varying lordosis, while pelvic tilt was introduced through a 6° lateral rotation. Results: The analysis revealed that sacral slope, ligament integrity, and joint symmetry significantly influence stress distribution. Hyperlordosis led to critical stress levels in interosseous and iliolumbar ligaments, exceeding failure thresholds. Asymmetrical gaps and pelvic tilt further altered the sacral rotation axis, increasing stress on sacroiliac joint ligaments. Conclusions: These findings highlight the importance of maintaining sacroiliac joint symmetry and lumbar–pelvic alignment to minimize stress on stabilizing ligaments, suggesting that treatment should focus on restoring alignment and joint symmetry. Full article

Background: Sagittal alignment in the lumbar spine is essential for spinal stability and functionality, with significant implications in surgical planning for spinal deformity correction. However, standardized lumbar partitioning, particularly identifying a critical sagittal alignment zone, remains underdefined. This study aims to establish a reliable lumbar partition to guide surgical decisions and optimize clinical outcomes. Methods: A systematic review of four major biomedical databases yielded 32 studies, of which 4 met the inclusion criteria. Studies on asymptomatic adults with segmental lordosis data stratified by pelvic incidence were analyzed. Lumbar lordosis values were converted to percentages, allowing for cross-study comparison. Sensitivity analysis and bias assessment were performed to ensure methodological rigor. Results: The findings identified the L3–L5 interval, especially around the L4 vertebra, as a critical biomechanical zone across various populations and pelvic incidence groups. Individuals with higher pelvic incidence had concentrated lordosis in lower segments, while those with lower pelvic incidence had greater lordosis in upper segments, underscoring the L3–L5 region’s stability as a surgical reference. Conclusions: The L3–L5 interval serves as a key partition zone for sagittal alignment, providing a stable reference for lumbar spine fusion. These findings offer a foundational clinical reference, potentially improving alignment outcomes and reducing postoperative complications. Full article

Background and Objectives: Musculoskeletal disorders affect a large portion of the population worldwide. The Musculoskeletal Health Questionnaire (MSK-HQ) is a helpful tool for assessing the health state of patients with these disorders. The primary goal of this study is to evaluate the psychometric properties of the MSK-HQ-IT in a population of kitesurfers. Materials and Methods: The study was conducted from September 2023 to July 2024. The questionnaire was completed using an online or paper form. Data were collected by submitting both the Italian and English versions of the MSK-HQ to a global sample of kitesurfers from various countries. Results: A total of 102 participants were recruited, consisting of 40 professionals and 62 non-professional kitesurfers. Cervical spine discomfort was significantly more prevalent among professionals (42.5%) compared to non-professionals (24%), as well as right shoulder pain (37.5% vs. 22.5%) and right wrist pain (12.5% vs. 3.2%). Non-professionals exhibited a significantly higher prevalence of functional limitations in the lumbar spine (25.8% vs. 5%) and reported more thoracic pain (21% vs. 17.5%). These findings indicate differing biomechanical stress patterns between the two groups, with professionals showing higher upper limb strain and non-professionals experiencing more lower back issues due to harness reliance. Conclusions: The MSK-HQ proved to be a reliable and valid tool for assessing musculoskeletal health in kitesurfers. The study highlights distinct injury patterns between professionals and non-professionals, with professionals being more prone to upper limb injuries and non-professionals showing a higher prevalence of lumbar and thoracic spine issues. These findings emphasize the need for targeted injury prevention strategies. Further research should focus on expanding the sample size and investigating long-term impacts of repetitive high-impact landings on musculoskeletal health in kitesurfers. Full article