Search Results (118)

Background/Objectives: Spinal alignment is a key determinant of biomechanical function and postural stability, particularly during periods of growth and development. Three-dimensional (3D) surface topography offers a non-invasive method for assessing spinal posture. This study aimed to evaluate spinal alignment parameters in a mixed adolescent and adult population, to investigate sex-related differences, and to analyze biomechanical relationships between spinal components. Methods: A total of 98 participants (aged 11–45 years) underwent 3D spinal surface topography assessment. Descriptive statistics were calculated for sagittal, coronal, and rotational parameters. Group comparisons between sexes were performed using independent samples t-tests. Pearson correlation analysis and linear regression were used to assess the relationships between spinal parameters. Logistic regression analysis was conducted to identify predictors of clinically relevant rotational asymmetry (surface rotation RMS > 6°). Results: Most participants exhibited near-physiological sagittal alignment, with thoracic kyphosis and lumbar lordosis within normal ranges. However, approximately 20% demonstrated clinically relevant rotational asymmetry. Female participants showed significantly higher rotational asymmetry compared to males (p = 0.008), while sagittal parameters did not differ significantly. Strong correlations were observed between thoracic kyphosis and cervical sagittal displacement (r = 0.77). Rotational asymmetry was negatively correlated with sagittal parameters and significantly predicted coronal imbalance (β = 0.38, p < 0.01; R² = 0.21). Conclusions: 3D surface topography provides a non-invasive method for assessing external postural alignment and surface-based asymmetries. Rotational asymmetry appears to represent a relevant component of spinal imbalance and is associated with coronal deviation within a multi-planar framework. These findings support the use of integrated biomechanical assessment in the evaluation of spinal alignment. Full article

Background and Objectives: Temporomandibular disorders (TMDs) are prevalent conditions affecting the temporomandibular joint and associated musculature, arising from a complex interplay of biomechanical, neuromuscular, and psychosocial factors. Increasing evidence supports functional interconnections among the TMJ, cervical spine, and shoulder girdle, suggesting that dysfunction in one region may influence others; however, these relationships remain incompletely understood. This study aimed to evaluate the association between scapulohumeral trauma, postural abnormalities, and TMDs, and to assess their evolution following interdisciplinary rehabilitation. Materials and Methods: A retrospective observational study with prospective follow-up was conducted in patients with scapulohumeral fractures associated with TMD and postural abnormalities. Postural parameters and the clinical features of temporomandibular disorders (TMDs) were evaluated at baseline and follow-up using a structured clinical assessment informed by the DC/TMD framework, together with clinical examination, electromyographic analysis, and mandibular mobility measurements. Postural evaluation was performed using digital baropodometric analysis (Free Med™ platform with FreeStep™ software, standard Medica sensor, Rome, Italy. Patients received individualized multidisciplinary treatment, including orthopaedic rehabilitation, occlusal splint therapy, physiotherapy (twice weekly), pharmacological management, and odonto-periodontal care. Statistical analyses were performed using non-parametric tests (p < 0.05). Results: Significant postural improvement was observed (p < 0.01), with the proportion of patients with normal posture increasing from 0% to 22.2% and the proportion with moderate forward lean decreasing from 53.3% to 15.6%. TMD severity decreased progressively across evaluations (Friedman χ² = 72.35, p < 0.01). No statistically significant differences were found between treatment groups with respect to postural outcomes, although descriptive differences in TMD improvement were observed at later evaluation points. Conclusions: Interdisciplinary rehabilitation was associated with significant improvements in both postural alignment and TMD severity. Scapulohumeral trauma may be associated with alterations in TMJ function and overall posture, while multimodal therapy supports functional recovery. Further randomized controlled studies are needed to confirm these findings. Full article

Aim: The aim of this study is to evaluate the effect of restorative crown materials with different elastic moduli on stress distribution in dentin and supporting tissues of pulpotomized primary anterior teeth under multi-directional loading conditions using the three-dimensional finite element analysis method. Materials and Methods: A three-dimensional model of a maxillary primary central incisor was created based on anatomical data. A clinical pulpotomy scenario was simulated using mineral trioxide aggregate (MTA) and resin-modified glass ionomer cement. Three models were analyzed: healthy tooth (control), Bioflx crown, and prefabricated zirconia crown. Frontal, oblique, and vertical loads were applied to represent functional and traumatic conditions. von Mises and principal stress distributions in the crown, dentin, and supporting tissues were evaluated. Results: In the prefabricated zirconia crown group, higher von Mises stress values were observed under all loading conditions, with significant stress concentrations particularly in the cervical region. In contrast, the Bioflx crown group exhibited lower stress values and a more homogeneous stress distribution. While the stress patterns in the Bioflx group were found to be closer to those of the control group, more localized stress accumulation was observed in the zirconia crowns. No significant differences were observed between the groups in the bone tissue. Conclusions: The elastic modulus of restorative materials plays a decisive role in the stress transfer mechanism. It is believed that materials with dentin-like mechanical properties may provide a more balanced and physiological stress distribution. Multi-directional loading analysis highlights the importance of evaluating the biomechanical behavior of restorative materials under more realistic conditions. Further advanced experimental and clinical studies are needed to clinically validate these findings. Full article

The Patagonian huemul (Hippocamelus bisulcus) and the Southern pudu (Pudu puda) are native South American cervids that differ in body size, ecology, and conservation status. However, quantitative evidence linking vertebral trabecular microarchitecture with biomechanical behavior in these species remains scarce. This study aimed to comparatively characterize vertebral trabecular bone structure and its mechanical response using an integrative, non-destructive approach. Vertebral bodies from cervical, thoracic, and lumbar regions were analyzed using high-resolution micro-computed tomography to quantify structural parameters, followed by finite element analysis to estimate deformation and von Mises stress under standardized axial compression. Both specimens exhibited consistent regional variation, with cervical vertebrae showing lower density and organization, and thoracic–lumbar vertebrae displaying denser trabecular networks. The Southern pudu specimen appeared to present a more homogeneous microarchitecture and a relatively uniform mechanical response along the vertebral column. In contrast, the Patagonian huemul specimen tended to show greater structural heterogeneity, with apparently higher deformation and stress values, particularly in the cervical region. These findings suggest that trabecular organization may contribute to the differences in vertebral mechanical behavior observed between the analyzed specimens. This study provides a preliminary comparative baseline for understanding skeletal adaptation and structural vulnerability in South American cervid species. This exploratory analysis is based on single specimens per species and should be interpreted as preliminary evidence rather than population-level inference. Full article

Finite element analysis is widely used to study spinal biomechanics and to compare surgical strategies under controlled loading conditions. By allowing variation in alignment, fixation, and implant design, these models provide insight into stress redistribution and motion changes that are difficult to isolate experimentally. This review examines spine surgery-focused finite element studies published between 2018 and 2024, with emphasis on interbody fusion techniques, adjacent segment mechanics, and implant-related stress behavior. Across lumbar fusion models, constructs incorporating anterior column support demonstrate lower posterior instrumentation stress than posterior-only approaches, with lateral lumbar interbody techniques showing reduced rod and screw stresses across multiple loading conditions compared with posterior lumbar interbody or posterolateral fusion constructs. In the cervical spine, comparisons of plated and zero-profile anterior cervical discectomy and fusion devices show smaller increases in adjacent-level motion and intradiscal pressure with zero-profile constructs, alongside higher localized stress at fixation interfaces. More recent studies apply finite element methods to implant optimization, alignment planning, and patient-specific modeling. Together, these findings suggest that finite element analysis is increasingly used to support surgical planning and implant design, with continued advances in validation and patient-specific simulation likely to strengthen its clinical relevance. Full article

Cervical spondylosis is a common cause of spinal cord dysfunction, and anterior cervical discectomy and fusion (ACDF) is widely employed when conservative treatment fails. Conventional implant systems such as the cervical cage with plate (CCP) and zero-profile stand-alone cage (ZPSC) are commonly used to enhance spinal stability and promote fusion, but they are associated with complications including dysphagia and adjacent segment degeneration. To address these limitations, a novel flexible plate cage system (FPCS) has been developed to optimize biomechanical performance while minimizing surgical risk. In this study, a finite element model of the C3–T1 cervical spine was constructed to simulate ACDF at the C5–C6 level using CCP, ZPSC, and FPCS implants. Under standardized loading conditions, von Mises stress was analyzed in the bone, intervertebral disc, endplates, cage, and screws, using the mean of the top 5% stress values to ensure accuracy. All surgical models showed increased stress compared to the intact reference spine. The ZPSC model exhibited the highest stress in the cage and screws, suggesting a more concentrated load path. The CCP model showed a more evenly distributed stress profile, particularly affecting the inferior adjacent segment. The FPCS model demonstrated moderate cage stress, reduced screw stress, and the highest plate stress, indicating a design that effectively redirects mechanical load from the screw-bone interface toward the anterior plate. This may be related to the unique structural configuration of the FPCS, which secures screws horizontally into the anterior vertebral body without penetrating the endplates. These findings suggest that the FPCS may offer a biomechanically favorable alternative to existing ACDF implants. Full article

Objectives: This study aimed to analyze the three-dimensional displacement of maxillary first molars using a finite element model with two headgear configurations, namely cervical and horizontal pull headgears, as well as pendulum, infrazygomatic miniscrews, Bollard miniplates, Advanced Molar Distalization Appliance (AMDA), and Beneslider. The goal was to clarify how variations in anchorage design and force direction influence molar movement across the sagittal, vertical, and transverse planes. Methods: A three-dimensional finite element model of the maxillary dentition and supporting structures was constructed using reference anatomical data and standardized material properties. Each appliance was virtually simulated under its clinically recommended force magnitude and direction to ensure realistic biomechanical conditions. The orientation of each force vector relative to the molar’s center of resistance (CR) was analyzed, and resulting tooth displacements were quantified along the sagittal (Z), vertical (Y), and transverse (X) axes using 49-node reference paths connecting key anatomical landmarks. Results: Appliances applying forces through or above the molar CR, such as the AMDA, infrazygomatic miniscrews, and Bollard miniplates, produced nearly bodily distalization with minimal tipping (<0.6° (range 0.3–0.6°)) and slight intrusion (−0.12 to −0.18 mm). Conversely, systems delivering forces below the CR, such as the cervical headgear and pendulum, resulted in greater crown tipping and extrusion. The Beneslider exhibited an intermediate displacement pattern with moderate vertical control. Conclusions: Force vector height and direction relative to the molar CR critically determine 3D displacement behavior. Skeletal anchorage and adjustable systems, particularly the AMDA, demonstrated the most controlled distalization pattern with minimal tipping, whereas conventional tooth-borne designs induced more tipping and extrusion. Full article

Background/Objectives: In the past few decades, there have been advancements in surgical techniques, improved understanding of spinal biomechanics, and awareness of complications associated with halo vest (HV) use with resultant surgical treatment of various pathologies that cause acute or chronic atlantoaxial instability. The purpose of this study was to see how HV usage has changed over time. Methods: A retrospective analysis of the North American Clinical Trials Network database. Patients with cervical spinal cord injury from 2006 through 2019 were identified and the trend of HV use was analyzed. Results: The mean age of patients who received HV was 37.4 years and 50 for those treated with other options, p < 0.0001. Its use consistently declined after 2009. After 2015 this decline reached nil in the database (p < 0.0001). Patients between 45 and 59 years (3.4%) and Above 60 years (2.8%) group had the least treatment using HV. Fall accident (4.7%, p = 0.0295) and central cord syndrome (4.6%, p = 0.0004) were associated with low HV use. Pulmonary complications were higher (89.4%) with HV use (vs. 65.9% with no HV), p = 0.0008. Pulmonary complications with HV decreased after 2012. Conclusions: HV as treatment option for conditions involving the cervical spine has decreased. This declining trend is attributable to decreased use in older individuals due to higher rates of complications and unfavorable outcomes with its use. The decreasing trend appears to coincide with published data showing better outcomes with surgical treatment and unfavorable outcomes with HV use. Full article

Infiltrative lipomas involving the upper cervical spine present a significant surgical challenge, as the extensive muscular resection required for tumor control often leads to severe structural instability. This report describes the surgical treatment of an infiltrative lipoma that extensively invaded the cervical area in a 9-year-old dog. Following wide surgical debulking, a dual-plane stabilization strategy was employed. Ventral stabilization was attempted using standard C1–C2 transarticular screw fixation, while a modified dorsal stabilization technique anchored the occipital protuberance to the C2 spinous process using an ultra-high molecular weight polyethylene (UHMWPE) suture construct, combined with nuchal ligament reconstruction. Follow-up at 78 days revealed failure of the ventral implants, characterized by immediate improper positioning of the right screw and subsequent migration of the left screw. Despite these complications and confirmed tumor recurrence, the patient maintained normal neurological function and clinical cervical stability. This clinical course was suggestive of fibrous or early osseous union at the atlantoaxial joint. These findings suggest that the modified dorsal stabilization technique provided critical biomechanical support, effectively compensating for the compromised ventral fixation, and may represent a potential surgical option for managing extensive occipito-cervical instability in dogs. Full article

Background: Children’s behavior and lifestyle are changing rapidly, potentially exceeding the capacity of physiological adaptation. Contemporary lifestyles may negatively affect spinal development and contribute to dysfunction and premature degeneration. Despite the increasing prevalence of postural changes, cervical spine disorders in adolescents remain under-researched. Methods: This narrative review is based on a comprehensive search of PubMed/MEDLINE and Scopus. The search strategy included a broad review of anatomical and biomechanical literature from the past 25 years and a focused review of studies from the last 15 years to reflect recent generational changes. Results: The immature spine has distinct structural and biomechanical characteristics that increase susceptibility to maladaptive responses to unbalanced forces. High screen time is associated with sedentary behavior and increased consumption of ultra-processed foods, which may affect metabolic health and musculoskeletal development. Childhood and adolescent obesity are increasingly prevalent and may influence spinal development, including through myosteatosis. Data on the consequences of cervical and lumbar lordosis loss in adolescents remain limited. Although degenerative spinal disorders are well recognized in adults, their identification in younger populations may be inadequate. Conclusions: Modern lifestyle factors pose a growing risk to children’s spinal health through complex interactions among behavioral, metabolic, and biomechanical mechanisms. The developing spine’s vulnerability and the coexistence of multiple, interrelated risk factors support the need for integrated preventive strategies rather than single-factor interventions. Future studies should focus on models capturing these interactions and their long-term consequences. Full article

Introduction: Type II odontoid process fractures are common in the adult population, and anterior screw fixation aims to restore C1–C2 complex stability while preserving cervical motion. This study focuses on the numerical analysis of odontoid fractures, evaluating the structural behavior after anterior screw fixation using finite element simulations. Methods: Forty-eight patients (males, females, 74 years old on average) diagnosed with type II odontoid fractures and treated surgically between 2015 and 2023 were included in the study. Various loading conditions (magnitude and direction) were simulated to analyze displacements and stress distributions after screw insertion. Results: Screw fixation significantly fixes fractured vertebrae, but stress and deformation are considerably larger than in unfractured cases. Posterior oblique loads produced the highest stress concentrations, particularly at the base of the odontoid and the screw-bone interface. Male models exhibited greater total deformations and stresses under the same loading conditions, suggesting relevant biomechanical differences based on sex. Conclusions: Anterior odontoid screw fixation provides effective stabilization in type II odontoid fractures, although its performance depends on factors such as load vector and patient-specific anatomical characteristics. These findings support the use of FEM simulation as a valuable tool for personalized surgical analysis. Full article

Spinal fusion remains a common surgical treatment for degenerative cervical spine pathology. By eliminating segmental motion, fusion alters spinal biomechanics and redistributes mechanical loads to adjacent levels. These changes contribute to adjacent segment degeneration (ASD). Motion-preserving spinal implants have been developed to address these limitations. Cervical disc arthroplasty (CDA) is the most widely used example. Such devices aim to maintain physiologic kinematics while preserving segmental stability. Their biomechanical behavior varies with implant design, material properties, and constraint characteristics. Previous research does not holistically compare fusion with motion-preserving treatments on the spine, resulting in an incomplete understanding of when motion-preserving devices should be considered in treatment over fusion constructs and which specific motion-preserving implants are most appropriate. This narrative review synthesizes experimental, computational, and clinical studies comparing rigid fusion constructs to motion-preserving technologies in the cervical spine. Emphasis is placed on segmental range of motion, load transmission, intradiscal pressure, facet joint forces, and adjacent-segment mechanics. By comparing effectiveness across motion-preserving treatments, alongside their effectiveness to fusion constructs, we found that CDA more closely preserves near-physiologic motion compared to fusion. Taken together, this review underscores the importance of biomechanics-informed implant design for guiding future innovation in spinal implant technologies. Full article

Self-organizing systems arise in complex biomechanical structures, human locomotion, and neural control hierarchies, yet quantitative methods for describing order formation and loss of stability remain limited. This study develops a mathematical framework for analyzing self-organization using entropy-based measures, indicators of chaotic dynamics, and network-theoretic structure. The approach (the LET framework) combines Lyapunov exponents with entropy families and graph metrics (algebraic connectivity, Load-Path Heterogeneity Index) to: (i) examine transitions between ordered and disordered states, (ii) assess sensitivity to perturbations, and (iii) characterize structural coherence in evolving cervical spine kinematics. Analytical models and computational validations are presented for cervical stability and post-operative Adjacent Segment Disease (ASD) using the Branney–Breen dataset. The findings indicate that entropy and chaos measures identify regime shifts and the emergence of a “stability corridor” more clearly than task-oriented indices, and provide finer resolution of dynamical variability within self-organizing processes. Network metrics complement these results by linking local segmental interactions to global structural fragility transfer. The study shows that entropy, chaos indicators, and network structure together form a consistent basis for describing self-organization in biomechanical systems, enabling quantitative comparison of dynamical regimes and improved interpretation of emergent pathological behavior. The approach utilizes a hybrid kinematic surrogate model to resolve passive and active components, bypassing direct force measurements by employing viscoelastic mechanotransduction principles. Full article

Background: Mechanization in olive harvesting has improved productivity but introduced new ergonomic challenges, particularly related to vibration exposure and sustained overhead work. This study investigates the acute and short-term physiological effects of using an electric olive harvester through objective instrumental assessment. Methods: Ten healthy male volunteers performed a standardized 15-min simulated harvesting task using an electric olive harvester. Muscle tone, stiffness, and elasticity of bilateral deltoid, biceps, and triceps were assessed by myotonometry at baseline (T0), immediately post-task (T1), and after 2 h recovery (T2). Infrared thermography evaluated cervical, dorsal, and lumbar skin temperature at the same timepoints. Results: Significant, side-dependent alterations in myotonometric parameters were observed, with marked increases in tone and stiffness of dominant upper-limb muscles and asymmetric adaptations between limbs (p < 0.001, large effect sizes). Infrared thermography revealed significant post-task reductions in skin temperature across spinal regions, with a partial return toward baseline within the 2 h observation window (p < 0.01). These findings describe short-term, task-related thermoregulatory responses following sustained work. Conclusions: Even short-term use of electric olive harvesters induces measurable biomechanical and thermophysiological stress. The integrated use of myotonometry and infrared thermography provides a sensitive, field-adaptable framework for early ergonomic risk detection and prevention of work-related musculoskeletal disorders in agriculture. Full article

Objectives: We aim to investigate cervical biomechanical alterations associated with adenomyosis using shear-wave elastography (SWE), and to explore the discriminative potential of cervical SWE parameters. Methods: In this prospective study, 84 patients with adenomyosis, diagnosed both clinically and by ultrasonography according to the MUSA parameters, and 65 healthy women underwent elastography to the cervix with SWE. Six areas of the cervix were evaluated: anterior and posterior internal os, middle part of the cervix, and external os. Results: The adenomyosis group showed a significantly higher cervical length (27.3 ± 5.5 mm vs. 23.8 ± 4.6 mm), as well as greater anterior (11.3 ± 2.4 mm vs. 9.9 ± 1.3 mm) and posterior (11.3 ± 2.2 mm vs. 10.5 ± 1.8 mm) cervical measurements compared with the controls (p < 0.001). SWE showed higher stiffness measurements for the anterior and posterior internal os (22.3 ± 5.4 kPa and 22.2 ± 4.9 kPa) compared with the controls (15.5 ± 5.8 kPa and 15.7 ± 5.6 kPa, respectively; p < 0.001). Receiver operating characteristic analysis demonstrated high discrimination for these measurements, with area under curve values of 0.804 for the anterior internal os and 0.808 of posterior internal os. Optimal cut-offs were 17.5 kPa (sensitivity 82%, specificity 70%) and 18.5 kPa (sensitivity 81%, specificity 74%). Conclusions: Cervical elastography may serve as a non-invasive adjunctive tool for exploring disease-related biomechanical changes and for supporting imaging-based assessment of adenomyosis. Full article