Search Results (276)

Extra-articular distal humerus fractures present surgical challenges, often requiring technically demanding posterior approaches with high radial nerve injury risks or off-label use of anatomically mismatched proximal plates. This study aimed to computationally design and optimize a novel anterior osteosynthesis plate for these fractures. A three-dimensional fracture model was developed, utilizing a parametric design exploration and finite element analysis to evaluate fourteen plate geometries. Evaluated variables included length, thickness, screw configuration, and locking mechanisms under physiological axial compression, bending, and varus loads. The analysis revealed that plate thickness primarily determines construct stability, with a four-millimeter profile optimally balancing rigidity and a low anatomical footprint. Lengths exceeding 40 mm yielded diminishing stability returns, while a dense distal locking screw configuration proved essential for maintaining fracture reduction. Compared to conventional clinical systems, the optimized plate substantially reduced the severe axial instability observed in extra-articular distal humerus plates and mitigated the critical bending stress concentrations inherent to proximal humeral internal locking systems. By achieving balanced, multi-planar stability with a minimized footprint, this novel design provides a favorable mechanical environment for secondary bone healing while facilitating a less invasive surgical approach. Full article

Technological development in surface treatment for biomedical implants has advanced rapidly, yet the integration of additive manufacturing with controlled nano topography remains underexplored. This study investigates a novel bioactive kinetic screw (BKS) produced by 3D printing and CNC machining, followed by different anodization treatments: plasma electrolytic oxidation (PEO), hard anodization (HA), and soft anodization for TiO₂ nanotube (TNT) formation. Scanning electron microscopy revealed that PEO created a uniform macro–micro porous surface with pore sizes ranging from 5–15 µm and porosity values of 22.4 ± 3.2%, while HA produced smaller, less homogeneous pores (0.5–2 µm, porosity 10.7 ± 2.6%). TNTs were successfully formed with an average diameter of 80 ± 12 nm, although distribution was non-uniform in screw grooves. Preliminary finite element analysis demonstrated that Ti6Al4V nanotubes (diameter 50 nm, length 500 nm) withstood applied torque with maximum von Mises stress of 1.5 × 10⁻⁸ N/nm² and maximum strain of 3.56, indicating mechanical resilience compatible with early implant loading. The findings demonstrate that the proposed anodization protocols generate distinct hierarchical surface morphologies on BKS implants while preserving implant geometry. These results provide a structural basis for future investigations of biological performance. Full article

Background: Allograft bone remains an attractive option for anterior cervical corpectomy and fusion (ACCF), but its use can be limited by variable graft geometry, insufficient endplate contact, and operator-dependent trimming. This study aimed to develop a titanium end-disc-assisted allograft construct with a standardized cutting and assembly system and to preliminarily evaluate its static mechanical integrity under axial compression, compression-shear, and torsional loading. Methods: The construct consisted of a controlled-length bone graft, two Ti6Al4V end-discs, and four countersunk fixation screws, forming a graft–disc construct with a maximum total height not exceeding 40 mm. The end-discs incorporated angled screw holes, bone-graft filling spaces, and enlarged contact surfaces. A modular preparation system was designed for graft clamping, length definition, guided cutting, alignment, pre-drilling, and screw fixation. Porcine rib specimens were used as an allograft substitute. Native bone and assembled constructs were tested under static compression, compression-shear, and torsion. Results: The system produced standardized constructs. Except for axial compressive stiffness, the assembled constructs showed numerically higher compressive yield force, shear stiffness, shear yield force, torsional stiffness, and yield torque than native bone; however, these findings were interpreted descriptively because of the limited sample size. Failure occurred mainly within the bone, with no obvious failure at the bone–titanium interface, titanium end-discs, or fixation screws. Conclusions: The proposed system enabled standardized graft preparation and construct assembly. Further fatigue, subsidence, and clinically relevant cervical spine model testing are required. Full article

Background: Palatal orthodontic mini-implants are increasingly used for sagittal, vertical, and transverse mechanics, including molar distalization, mesialization, posterior intrusion, impacted tooth traction, and miniscrew-assisted rapid palatal expansion. Yet site selection is often discussed as if anatomical bone availability were the dominant determinant of performance. Objective: This scoping review maps direct palatal evidence and supporting mechanistic evidence on how palatal substrate, miniscrew design, insertion protocol, digital planning, biomaterial surface, and biomechanical loading interact to determine primary stability, loaded stability, survival, and failure risk. Methods: Records were searched in PubMed/MEDLINE, Scopus and Web of Science Core Collection and organized into two evidence streams, as follows: P1 direct palatal evidence and P2 supporting mechanistic/biomaterials evidence. Data were charted using a Bone–Screw–Force framework. Results: The evidence indicates that anterior palatal and anterior paramedian sites are usually favorable for routine anchorage, but posterior sites, PPSAIS, and MARPE locations may warrant patient-specific three-dimensional assessment when clinical and conventional radiographic evaluation is insufficient. Primary stability emerges from cortical thickness, trabecular quality, effective intraosseous length, miniscrew diameter, thread design, insertion angle, pilot-hole protocol, torque, force magnitude, and biological response. Digital workflows are best interpreted as trajectory-control technologies rather than as convenience tools. Biomaterial and surface evidence remains promising but insufficiently connected to palatal-specific outcomes. Conclusions: Palatal miniscrew performance should be reframed as an interface problem rather than a site-only problem. A Bone–Screw–Force framework can support biomechanically driven site selection while identifying where quantitative evidence remains insufficient. Full article

Background: Automated pedicle screw planning (ASP) can initialize trajectories and implant dimensions, but correlation with implanted screws does not establish agreement. We quantified the association and agreement between ASP recommendations and actual intraoperative implant selection (AIS) and examined pathology, asymmetric planning, and available safety outcomes. Methods: This retrospective single-center study included 103 consecutive patients treated with thoracic or lumbar instrumentation from January 2021 to January 2024. The dataset contained 351 bilateral screw-pair records. Pearson and Spearman correlations, linear regression, and Bland–Altman analyses were supplemented by patient-clustered bootstrap 95% confidence intervals (CIs), pathology-stratified estimates, and a sensitivity analysis excluding a verified 94 mm iliac-fixation observation. Results: Diameter showed moderate correlation (Pearson’s r = 0.635, 95% CI 0.542–0.721; Spearman’s rho = 0.679, 95% CI 0.554–0.767; both p < 0.001). Length also showed moderate correlation (Pearson’s r = 0.675, 95% CI 0.565–0.754; Spearman’s rho = 0.600, 95% CI 0.450–0.714; both p < 0.001). For ASP minus AIS, the diameter bias was −0.75 mm (95% CI −0.86 to −0.64), with limits of agreement from −2.00 to 0.50 mm. The length bias was −0.15 mm (95% CI −1.05 to 0.79), with limits from −12.30 to 12.00 mm. The 94 mm value was verified as a genuine iliac-fixation observation; excluding it changed Pearson’s r only from 0.675 to 0.679. Asymmetric ASP length recommendations occurred in 115/351 pairs (32.8%), usually by 5 mm. Conclusions: ASP tracked overall implant-size trends but did not provide interchangeable estimates of surgeon-selected dimensions. Its systematic diameter underestimation and broad pair-level differences support its use as an initialization and review aid, with final sizing retained as a surgeon decision. Full article

Background/Objectives: Poor bone quality significantly increases the risk of mechanical complications after adult spinal deformity (ASD) surgery, including proximal junctional kyphosis (PJK) and proximal junctional failure (PJF). Although teriparatide enhances bone quality, its effectiveness in preventing junctional complications after extensive correction remains unclear. This study investigated whether preoperative teriparatide administration reduces the incidence of PJK and PJF in patients with compromised bone quality undergoing ASD surgery. Methods: This retrospective cohort study reviewed 292 patients (T-score < −1.0) who underwent ASD surgery between 2015 and 2023. Patients were divided into teriparatide (n = 59) and non-teriparatide (n = 233) groups. Propensity score matching (1:2 ratio) was performed using six covariates: age, preoperative pelvic incidence minus lumbar lordosis, preoperative T1 pelvic angle, upper instrumented vertebra (UIV) cementing, UIV screw angle, and fusion length, yielding 153 matched patients (52 teriparatide, 101 non-teriparatide). Results: After matching, all baseline characteristics were statistically similar, with no significant differences. The incidence of PJK and PJF did not differ significantly between the teriparatide and non-teriparatide groups (44.2% vs. 52.5%, p = 0.426; 9.6% vs. 9.9%, p = 1.000), nor did PJK subtype distribution (bony vs. soft-tissue). Multivariate analysis identified older age (odds ratio [OR] = 1.058), higher American Society of Anesthesiologists score (OR = 2.603, p = 0.002), UIV at the thoracolumbar junction (OR = 2.786), and greater postoperative thoracic kyphosis (OR = 1.044) as independent risk factors for PJK. Teriparatide use was not an independent predictor (OR = 0.872). Conclusions: Preoperative teriparatide did not significantly reduce the incidence of PJK or PJF after long-segment fusion for ASD. These findings suggest that improving bone quality alone is insufficient to prevent junctional complications, which are driven by complex biomechanical and patient-related factors inherent to extensive deformity correction. Full article

Fast-charging lithium-ion batteries require graphite anodes with low ionic transport resistance, yet systematic links between electrode manufacturing parameters and fast-charge performance remain scarce. This study shows that twin-screw extrusion (TSE) process conditions control electrode tortuosity, the geometric complexity of ionic pathways, by reshaping the binder network architecture without altering active material integrity. A central composite experimental design combined with multi-scale diagnostics identifies pore network tortuosity as the primary transport bottleneck. The optimized mild kneading condition (K4: 60 $\mathrm{wt}\%$ kneading zone solids, 7% kneading length, gentle screw design) reduces the 8–80% state-of-charge (SOC) charging time by $14.9$% relative to the intensive baseline (B1–B3: 70 $\mathrm{wt}\%$, 50% kneading length), matching conventional batch mixing. Regression analysis confirms a strong correlation between tortuosity and fast-charge performance ($R^2=0.86$), whereas the correlation with charge-transfer resistance is weaker ($R^2=0.59$). Mechanistically, mild kneading promotes reversible, sterically stabilized carboxymethyl cellulose (CMC) networks consistent with extended “loop-tail” polymer conformations. Intensive kneading is consistent with the formation of bridging gels that fail to arrest binder migration during drying and clog surface pores. A Pore-Homogeneity Index (PHI), derived from mercury porosimetry, quantifies the resulting microstructural heterogeneity, correlates with tortuosity ($R^2=0.76$), and characterizes pore network uniformity. The results identify local stress intensity as a primary factor influencing binder network formation and support tortuosity as an adjustable design parameter in continuous anode processing. Full article

Distal radial and ulnar fractures in miniature- and toy-breed dogs are associated with high rates of delayed union, non-union, and refracture. This retrospective observational study evaluated the outcomes of simple distal radial and ulnar fractures treated by open reduction and internal fixation using a locking plate in a non-rigid configuration. Ten fractures in eight dogs weighing less than 5 kg were included. Cases were selected according to predefined biomechanical construct criteria, including a plate bridge ratio > 0.7, plate span ratio > 10, plate working length > 40% of the plate length, and screw density < 0.6. The median radiographic follow-up was 224 days (range, 46–408 days). Radiographic bone healing was achieved in all cases, with a mean time to union of 53 days (range, 28–113 days), and healing occurred faster in skeletally immature dogs. Indirect bone healing with callus formation was observed in 7 of 10 fractures. Minor postoperative complications occurred in three cases and resolved with local treatment. No implant failures or refractures associated with previous screw holes were observed. A reduction in ulnar thickness was identified in evaluable cases, although this finding remained stable during follow-up and did not appear clinically relevant. These findings suggest that locking plate fixation in a non-rigid configuration provides reliable bone healing with a low complication rate in simple distal radial and ulnar fractures of miniature- and toy-breed dogs. Full article

Glued-in rod (GIR) connections are widely used in timber composite structures owing to their high load-bearing capacity, high stiffness, and concealed configuration. However, their shear behavior and design methodology under lateral loading remain insufficiently understood. In this study, monotonic shear tests were conducted to clarify the shear failure characteristics and load-transfer mechanisms of steel-to-timber GIR connections. The effects of rod diameter, anchorage length, timber strength grade, and rod orientation relative to the timber grain on the shear performance of the connections were systematically investigated. Self-tapping screw (STS) connections were also tested to compare the shear capacity, deformation behavior, and failure modes of the glued-in rod connections. Based on Johansen’s yield theory and the observed failure modes, shear capacities, and load–slip curves, the shear capacity prediction method and the main influencing factors were evaluated. The results indicate that steel-to-timber GIR connections primarily exhibit a combined failure mode involving timber embedment crushing and rod bending deformation or shear fracture under monotonic shear loading. Shear capacity increases markedly with increasing rod diameter. For the 12 mm rods examined in this study, anchorage length has a limited effect on shear capacity once it exceeds approximately 10d. Connections with rods oriented parallel to the grain demonstrate higher load-carrying capacity and deformation capacity than those with rods perpendicular to the timber grain. Furthermore, the prediction accuracy of the Eurocode 5-based calculation method varies with rod diameter: the calculated capacities agree well with the experimental values for small-diameter rods (10 mm and 12 mm), whereas the predictions for larger-diameter rods (14 mm and 16 mm) are conservative. Full article

Background: Successful spinal stabilization depends not only on early mechanical fixation but also on durable biological integration at the bone–implant interface. This study aimed to compare a two-stage allograft-augmented fixation strategy, intended to promote biological fixation, with conventional posterior segmental stabilization (PSS) in the treatment of screw loosening following multilevel spinal surgery for degenerative spine pathology. Methods: This retrospective comparative study included 40 patients who underwent multilevel spinal stabilization between January 2022 and February 2025, with follow-up completed by November 2025. Patients were divided into a conventional PSS group (n = 28) and a two-stage allograft-augmented fixation group (OI-focused strategy, n = 12). Demographic characteristics, comorbidity burden, length of hospital stay, complications, Visual Analog Scale (VAS), the Oswestry Disability Index (ODI), and sagittal radiographic parameters—including lumbar lordosis (LL), sagittal vertical axis (SVA), sacral slope (SS), and pelvic incidence (PI)—were evaluated preoperatively and at 1, 6, and 9 months postoperatively. Results: The groups were similar in terms of age, sex, body mass index, smoking status, and number of operated levels. Despite the significantly higher Charlson Comorbidity Index and Elixhauser Comorbidity Index scores in the OI-focused group, hospital stay was significantly shorter. VAS and ODI scores were comparable preoperatively and at 1 month; however, significantly better pain and functional outcomes were observed in the OI-focused group at 6 and 9 months. Radiologically, SVA was significantly lower in the OI-focused group at 6 and 9 months. Late differences were also observed in LL and SS, while PI remained similar between groups. Fusion-related findings were interpreted cautiously because fusion was assessed using plain radiographs and osseointegration was not directly measured. Conclusions: The two-stage allograft-augmented fixation strategy was associated with better mid-term pain control, improved functional recovery, and better preservation of selected sagittal alignment parameters compared with conventional PSS. However, these findings should be interpreted cautiously due to the retrospective design, limited sample size, imbalanced groups, absence of direct osseointegration measurement, and lack of CT-based fusion analysis. Full article

This study presents the design, development, and experimental validation of an automated flat blade grinding machine for the wood processing and plastic recycling industries in Ecuador. The machine was engineered following the VDI 2221/2222/2225 design methodology, integrating SolidWorks-based 3D modeling and ANSYS finite element analysis (FEA) to validate critical structural components. The selected configuration includes a Type 6 alumina grinding wheel (38A-60-K-VS), a mechanical clamping system, cutting fluid cooling, and a hardwired electromechanical control system that does not require a programmable logic controller (PLC). FEA results confirmed adequate safety factors (ηs > 16; ηf > 14) for the ACME 3/4–8 power screw under operational loads. Experimental testing on blade specimens (thickness: 3 mm; length: 70 mm; steel up to 60 HRC) demonstrated that four grinding passes at a 45° inclination angle reduced mean surface roughness (Ra) from 5.39 ± 1.83 µm (used blades) to 0.162 ± 0.092 µm, achieving values comparable to new blades (Ra = 0.601 ± 0.153 µm): a point-estimate reduction of 97% in mean Ra relative to the used-blade condition. The automated process reduced average grinding time by approximately 30% compared to manual methods, while maintaining noise levels within the 85 dB occupational exposure limit. Operator satisfaction surveys rated the system above 4.5/5.0 across all ergonomic and usability criteria. These results validate the proposed machine as a cost-effective, locally manufacturable solution to standardize blade maintenance in small and medium enterprises (SMEs) across Latin America. Full article

Background/Objectives: Ankylosing Spinal Disorders (ASDs) encompass a heterogeneous group of rheumatic diseases characterized by progressive ankylosis of the axial skeleton, including Ankylosing Spondylitis (AS), Diffuse Idiopathic Skeletal Hyperostosis (DISH), and Non-Radiographic Axial Spondyloarthritis (nr-AxSpA). Spinal ankylosis profoundly alters the biomechanical properties of the vertebral column, transforming it into a rigid long-bone equivalent and dramatically increasing fracture risk even after low-energy trauma. Once a fracture occurs, the long lever arm created by the ankylosed segments generates enormous mechanical stress at the fracture site, making surgical stabilization mandatory in the vast majority of cases. Long posterior instrumentation is the treatment of choice; however, no consensus exists regarding the optimal number of instrumented levels. The aim of this study is to clinically and radiologically evaluate long posterior instrumentation in the 3 + 3 (3 proximal and 3 caudal screws), 3 + 2 (3 proximal and 2 caudal screws), or 2 + 2 (2 proximal and 2 caudal screws) configuration for the treatment of traumatic ASD thoracolumbar vertebral fractures, in terms of implant failure, infection rate, and mortality. Methods: Between 2018 and 2023, 65 consecutive patients with ASD-related thoracolumbar vertebral fractures were treated at our institution. After applying pre-defined inclusion and exclusion criteria, 37 patients were enrolled. Patients were retrospectively divided into three groups according to the posterior arthrodesis configuration (notation indicates number of instrumented vertebral levels proximal + distal to the fracture: 3 + 3, 3 + 2, or 2 + 2). Radiological outcomes were assessed for loosening, screw cut-out, and implant breakage. Infection and mortality rates within 3 months from surgery were evaluated as secondary endpoints. Statistical analysis was performed using the Fisher exact test (significance set at p < 0.05). Results: Thirty-seven patients (28 males and 9 females; mean age 77 ± 7.3 years) were included, with a mean follow-up of 30 ± 5.3 months. Instrumentation configurations were as follows: 23 (3 + 3), 5 (3 + 2), and 9 (2 + 2). Three implant failures (8.1%) and four infections (10.8%) were recorded. Eleven patients died within 3 months of surgery. A statistically significant difference was found between instrumentation length and mechanical complications (p = 0.0468), while no significant difference was observed for infection (p = 1) or mortality rate (p = 0.137). Conclusions: In this exploratory retrospective cohort, the 3 + 3 configuration was associated with the lowest observed rate of implant failure in ASD thoracolumbar fractures, suggesting a potential mechanical advantage over shorter constructs that warrants confirmation in larger prospective studies. No significant correlation was found between instrumentation length and infection rate or early mortality. Prospective, multicentre studies with larger cohorts are warranted to establish definitive guidelines for instrumentation length in this challenging patient population. Full article

Objective: Perform endoscopic surgery for radiculopathy caused by compression fractures and evaluate the results. Methods: A total of 20 patients who underwent biportal endoscopic foraminotomy and unilateral screw fixation using a dynamic rod for radiculopathy secondary to osteoporotic compression fractures were included in this study. All surgeries were performed between July 2021 and January 2025. Patient demographic data, operated level, length of hospital stay, intraoperative blood loss, and operative time were reviewed. Radiological follow-up included assessment of segmental kyphosis, scoliosis, subsidence, and adjacent-level fractures. Complications and pain patterns—separately evaluated for back pain and radiculopathy—were assessed using the visual analog scale (VAS) preoperatively and during follow-up. Only single-level cases were included. Patients with infections, significant stenosis, instability, tumors, prior revision surgery, multilevel pathology, or ambiguous symptoms were excluded. Results: The mean age of the patients was 78.8 years (range, 69–89 years), reflecting an elderly cohort. The mean follow-up period was 13.0 ± 11.9 months (range, 1–41 months). The mean operative time was 164.8 ± 25.7 min, and the mean hospital stay was 10.2 ± 4.6 days (range, 4–25 days). The mean intraoperative blood loss was 126.5 ± 77.6 mL (range, 50–400 mL). One female patient developed postoperative pneumonia, which resolved after appropriate treatment; no other medical complications were observed. Radiculopathy improved significantly immediately after surgery and continued to improve during follow-up. Back pain also improved, but tended to persist to a mild degree. Radiologic evaluation revealed no significant changes in segmental lordosis, and there were no cases of subsidence, scoliosis, or symptomatic screw loosening during the available follow-up period. Conclusions: Biportal endoscopic foraminotomy with unilateral screw fixation may be an effective solution for radiculopathy caused by compression fractures. Full article

Background: Fractures of the upper cervical spine are challenging to treat due to their proximity to critical neurovascular structures and the need for immediate, stable fixation. Open posterior fixation remains the standard but is associated with soft-tissue disruption and morbidity. Minimally invasive, navigation-assisted pedicle screw fixation represents a viable alternative for older populations, significantly reducing surgical morbidity and tissue trauma. The present study evaluates the accuracy, safety, and perioperative outcomes of minimally invasive navigated posterolateral C1–C2 fixation. Methods: We conducted a retrospective consecutive case review of 51 patients who underwent minimally invasive C1–C2 screw fixation between 2019 and 2024. All procedures were performed using intraoperative O-arm imaging and StealthStation S8 navigation. Screw placement accuracy was assessed using the Bredow modification of the Gertzbein–Robbins and Heary classifications. Perioperative data, including operative time, screw dimensions, radiation dose, complications, and hospital stay, were recorded. Results: Fifty-one patients were included in the study. A total of 212 screws were placed. According to Gertzbein–Robbins grading, 92.4% were Grade A, 6.6% were Grade B, and 1% were Grade C. According to Heary grading, 95% were Grade I and 5% were Grade III. No vertebral artery injuries, new neurological deficits, or intraoperative hardware failures occurred. The mean screw lengths were 33.2 mm (SD = 3.38 mm) (C1) and 32 mm (SD = 4.30 mm) (C2). The mean operative time was 128 min (SD = 52.95 min). The mean radiation dose was 629.16 mGy·cm² (SD = 372.2 mGy·cm²). One superficial wound infection occurred. The median postoperative NRS was 4 (IQR: 4–5). The mean hospital stay was 4.21 (SD = 3.77) days. Conclusions: Our findings demonstrate that the presented approach for C1–C2 fixation is a highly accurate and safe alternative to open posterior fixation for upper cervical fractures. Full article

Background/Objectives: The aim of this study is to describe clavicular morphometric parameters and key bony landmarks relevant to plate-and-screw fixation and ligamentous reconstruction procedures. Methods: Morphometric measurements were performed on 179 adult human clavicles: 84 right and 95 left. Linear measurements were obtained using a Mitutoyo digital caliper (0.01 mm precision). Angular measurements were conducted using ImageJ software (LOCI, University of Wisconsin, Madison, USA). Results: The mean distance between the sternal articular surface and the midpoint of the sternoclavicular curvature was 49.23 ± 8.86 mm. The mean distance between the midpoints of the sternoclavicular and acromioclavicular curvatures was 65.16 ± 12.17 mm. The mean distance between the midpoint of the acromioclavicular curvature and the acromial articular surface was 41.58 ± 4.85 mm. The mean sternoclavicular angle was 153.31 ± 9.53° and the mean acromioclavicular angle was 119.95 ± 10.92°. The average thickness of the narrowest middle part of the clavicle was 11.61 ± 1.77 mm. The mean projection distance from the middle part of the clavicle to the most prominent point of the conoid tubercle was 43.81 ± 6.33 mm. The distances from the middle part of the clavicle to the medial trapezoid line and to the lateral impression of the costoclavicular ligament were 50.10 ± 6.31 mm and 42.29 ± 5.88 mm, respectively. The mean projected clavicular length was 142.76 ± 12.29 mm. Conclusions: In conclusion, these findings offer an anatomical reference that may assist radiological evaluation of clavicular shortening and support orthopaedic surgeons in implant selection and planning of ligament reconstruction procedures. Full article