Search Results (676)

Aneurysmal bone cysts (ABCs) are benign but locally aggressive osteolytic lesions that are rarely reported in dogs and may progress or recur following surgical treatment. This case report describes the diagnosis, surgical management, postoperative progression, and long-term outcome of an ABC affecting the left ulna of a four-month-old Labrador Retriever. Radiography and computed tomography revealed a rapidly progressive, expansile osteolytic lesion with marked cortical thinning. Histopathological examination supported the diagnosis of ABC, with no evidence of malignancy. Initial treatment consisted of corticotomy, intralesional curettage, autologous bone grafting, and stabilization of the cortical segment with lag screws. Despite complete clinical resolution of lameness, surveillance radiographs six weeks postoperatively demonstrated progression of the lesion proximal to the original surgical site. Revision surgery involving a larger cortical window and more extensive curettage was subsequently performed, followed by bone grafting. Histopathology again confirmed ABC without malignant transformation. The dog regained normal limb function, and serial radiographic and computed tomographic examinations demonstrated progressive osseous remodeling with no evidence of further progression or recurrence through 35 months of follow-up. This case highlights the importance of adequate surgical excision and scheduled postoperative imaging, as ABC progression may occur despite apparent clinical recovery. Full article

Purpose: This study investigated the surface morphology and roughness of the dental implant platform and abutment at their junction interface, comparing parameters before and after mechanical assembly (screwing). Methods: The experimental specimens comprised 40 implants from the TBR, Bone Level M System (TBR, France) with a diameter of 4.7 mm and a length of 10 mm, and 40 matching abutments from the same system (Titanium Standard Abutment, TBR, France) with a diameter of 4 mm and a gingival height of 3 mm. All components were fabricated from Grade 4 titanium. The implants and abutments were divided into two equal groups. In the first group (control), 20 implants and 20 abutments remained unassembled. In the second group, 20 implants were coupled with 20 abutments and tightened to the manufacturer-recommended torque. To achieve this, the implants were stabilized with pliers to prevent rotation, and the abutments were screwed using a screwdriver and a torque wrench at 30 N.cm. Subsequently, the abutments were unscrewed counterclockwise. Surface evaluations were conducted using scanning electron microscopy (SEM) and 3D surface modeling. Results: The obtained results demonstrate a statistically significant reduction in the parameters reflecting the roughness of the implant platform. Based on the analysis, a pronounced decrease in the average roughness (Ra, Rq) of the abutment was observed (p < 0.001). Furthermore, it was established that the implant platform exhibits nearly twice the surface roughness of the abutment even in its baseline state. Conclusions: Within the limitations of this in vitro study, a single tightening and removal procedure was associated with measurable changes in the roughness parameters and surface morphology of the implant platform and abutment. These findings indicate microtopographic adaptation at the conical interface under the tested conditions; however, biomechanical reliability and resistance to bacterial micro-leakage were not evaluated. Full article

Background and Clinical Significance: In two-stage implant treatment the cover screw must be removed at second-stage surgery. Removal is occasionally prevented by cold welding or seizure. When the drive slot is damaged by escalating torque, no standard salvage protocol has been established, and the implant body itself may ultimately require removal. Case Presentation: During second-stage surgery for three implants placed in the mandibular right posterior region (#44, #45, #46) of a 68-year-old man, the cover screw at the #46 site was seized and could not be loosened with a manual screwdriver. An attempt at removal with a contra-angle implant driver, set first to 20 Ncm and then to 35 Ncm, stripped the drive slot. The procedure was suspended, and a revision was performed two weeks later. A tungsten carbide bur was used under water irrigation to prepare a straight slot across the damaged screw head, and a crown remover with a narrowed flat-blade tip was engaged in this slot. The screw was retrieved intact and the internal connection of the implant remained serviceable. A healing abutment was connected and the implant was restored with a definitive prosthesis, which was in function at the most recent review. At seven weeks after delivery, the distance from the implant platform to the crestal bone was greater at #46 than at the two adjacent implants. Conclusions: This report describes a salvage technique that preserved the implant body without the use of a system-specific retrieval kit. The peri-implant bone level observed at the treated site indicates that the procedure may have been accompanied by a loss of crestal bone, and whether the technique is reproducible will require further cases. Full article

Background/Objectives: Evidence comparing cement- and screw-retained implant-supported restorations remains heterogeneous, particularly in augmented posterior maxillae. This study evaluated the association between definitive retention mode and peri-implant marginal bone level at a minimum 5-year follow-up after maxillary sinus floor elevation. Methods: This retrospective clustered cohort included 248 patients and 528 bone-level implants; radiographic measurements were available for 522 implants from 247 patients. Marginal bone level was assessed by CBCT immediately after implant placement and at least 60 months later. The primary adjusted analysis used generalized estimating equations with patient-level clustering and robust standard errors. Results: Mean marginal bone level at final follow-up was 0.133 mm for cement-retained and 0.105 mm for screw-retained restorations; the unadjusted difference was not statistically significant (Mann–Whitney U = 31,366; p = 0.064). In the primary GEE model, which excluded provisional retention because of its strong collinearity with definitive retention, definitive screw retention was not associated with marginal bone level at follow-up (B = −0.0028 mm; 95% CI: −0.0165–0.0108; p = 0.684). The time × definitive retention interaction was also not significant (B = −0.0069 mm; 95% CI: −0.0187–0.0049; p = 0.249). Conclusions: Definitive retention mode was not significantly associated with marginal bone level in the primary adjusted analysis, and longitudinal marginal bone change did not differ significantly between retention strategies. Sensitivity analyses indicated that estimates were influenced by the strong collinearity between provisional and definitive retention. These observational findings do not demonstrate superiority or equivalence of either retention strategy. Full article

Adaptive and multi-functional nozzle actuation is highly demanded for modern aero-propulsion systems. Realizing integrated thrust vectoring, variable exit-area adjustment and reverse-thrust generation within a compact layout still poses substantial challenges. Inspired by archerfish’s integrated flow-regulation mechanism, which relies on coordinated oral bones and muscles to generate asymmetric oral deformation for jet shaping, direction control and flow-passage switching, this paper develops a nozzle actuation mechanism drawing on the kinematics of the archerfish jaw-operculum system. The design integrates pitch vector adjustment, variable exit-area modulation (full-closure included), and reverse-thrust generation. A single electric-cylinder-linkage assembly drives the nozzle exit, while lead-screw actuators govern the operculum-mimicking flow-diversion structure for reverse-thrust switching. Validated by kinematic analysis and three-dimensional flow-field simulations, the mechanism delivers a maximum continuous geometric pitch deflection of 36° within 8 s and stepless exit-area adjustment ranging from 1.8 × 10⁴ mm² to full closure. It enables active modulation of jet mixing behaviours and reverse-thrust output for landing deceleration. Compared with conventional nozzles, this bionic configuration achieves a streamlined actuation layout, competitive vectoring performance, continuous area adjustability and reduced control complexity, offering an innovative bionic solution for adaptive aero-propulsion devices. Full article

Angled abutments and cantilever extensions in bar-supported full-arch implant prostheses may generate bending moments and localized stress concentrations within prosthetic components and peri-implant bone. Implant-supported rehabilitation becomes biomechanically more demanding in completely edentulous patients with posterior bone resorption. Therefore, understanding how connection geometry, cantilever length, and framework material influence prosthetic design is important. In this study, a three-dimensional mandibular model generated from CT data was used to compare conventional and spherical abutment–bar connection designs in All-on-Four prostheses with 30° angled posterior abutments. Cantilever lengths of 8, 10, and 12 mm were evaluated, and Ti6Al4V Grade 5 and PEEK were assigned as alternative bar prosthesis materials. Finite element analyses were performed in ANSYS Workbench, and von Mises stress distributions were evaluated in the bar prosthesis, prosthetic screws, abutments, implants, and surrounding cortical and trabecular bone. The results showed that increasing cantilever length increased stress levels in prosthetic components and bone tissues. The spherical connection design generally reduced stresses in the most critical distal components compared with the conventional design; however, this reduction was not uniform for all components, particularly in the PEEK models. The highest stress value was observed in the posterior angled abutment of the PC-12 model with a PEEK bar prosthesis (1592.2 MPa). Among the implant components, the lowest stress was observed in the anterior implant of the TS-8 model (27.99 MPa). In contrast, the lowest bone stress was recorded in the anterior trabecular bone capsule of the PC-8 model. These findings indicate that cantilever length and connection geometry are critical parameters in designing full-arch implant prostheses. At the same time, the use of PEEK as a bar material should be interpreted with caution under extended-cantilever conditions. Full article

Patient-specific Ti–6Al–4V fixation systems are increasingly used to stabilise the maxilla following segmental Le Fort I osteotomy; however, the biomechanical responses of complete locking and non-locking patient-specific fixation configurations remain insufficiently characterised. In this study, two patient-specific plate designs (a standard design and a reduced, minimally invasive design) were analysed by linear-elastic finite element analysis, each with locking and non-locking screws. Because they were developed for different indications and evaluated in distinct patient-specific anatomical models, between-model comparisons were considered descriptive. Vertical forces of 97.6, 206.9, and 257.0 N were applied bilaterally to the incisor and premolar regions, and the equivalent von Mises stress and total displacement were evaluated in the bone, plates, and screws. All results scaled linearly with load. Within the standard model, the locking configuration exhibited slightly greater bone, plate, and screw displacement than the corresponding non-locking configuration. Within the reduced model, it exhibited lower maximum bone, plate, and screw displacement by 16.4%, 19.2%, and 16.3%, respectively. Solver-reported local stress maxima were concentrated at the screw-head/plate-hole transition; because these isolated peaks were contact- and mesh-sensitive, they were not used to quantify relative screw loading or predict yielding. The modelled locking and non-locking fixation configurations therefore exhibited different, model-dependent displacement patterns. Further controlled simulations and experimental validation are required to determine the clinical relevance of these findings. Full article

Background and Objectives: The rehabilitation of the atrophic posterior maxilla with pterygoid implant presents a significant challenge due to complex regional anatomy and limited visual access. This study aimed to compare the accuracy of a dynamic computer-assisted implant surgery system (dCAIS) for pterygoid implant placement in fully and partially edentulous maxillae using radiographic marker registration (RMR) and markerless tracing registration (MTR), respectively. Materials and Methods: Forty pterygoid implants were retrospectively evaluated in 40 patients, divided into two groups: fully edentulous (n = 20) and partially edentulous (n = 20). Implant placement was performed using a dynamic navigation system (dCAIS), utilizing either bone-anchored mini-screws or tooth-surface tracing as reference points. Accuracy was assessed by superimposing preoperative plans with postoperative cone beam computer tomography (CBCT) scans. Coronal, apical, and angular deviations were measured and analyzed using the Data Science Workbench (version 14). The level of statistical significance was set at α = 0.05 (two-tailed). Results: The mean deviations for fully and partially edentulous maxillae measured 1.24 ± 0.27 mm and 1.40 ± 0.27 mm at the coronal level (p = 0.065), 1.30 ± 0.49 mm and 1.30 ± 0.54 at the apical level (p = 0.995), and 0.72 ± 0.38° and 0.82 ± 0.43° in angular deviation (p = 0.560), respectively. No statistically significant differences were found between the two groups. Notably, mean angular deviation was remarkably low (<1°) in both groups. Conclusions: No statistically significant between-group differences in accuracy were detected in coronal, apical, and angular deviations between the markerless tracing registration method in partially edentulous patients and the bone-anchored radiographic marker registration method in fully edentulous patients. Full article

Spinal surgery involves highly complex procedures where the risk of severe complications, including postoperative infections, may compromise both surgical success and patient survival. In this study, functional coatings for spinal screws were developed to promote bone integration and simultaneously prevent infection. The coating design employed a multilayer architecture based on poly(ε-caprolactone) (PCL) as the main structural layer, covered with chitosan (CS), a biocompatible polymer that enhances surface interaction with both the metallic substrate and the active agents. To stimulate bone regeneration, calcium β-hydroxy-β-methylbutyrate (HMB) was incorporated, while antimicrobial efficacy was achieved by embedding PLGA-based polymeric microspheres encapsulating gentamicin sulfate, a broad-spectrum antibiotic. The obtained results confirmed the successful integration of all components, as evidenced by FTIR and Raman spectroscopy, along with homogeneous surface morphologies observed via SEM analysis. Biological assays demonstrated significant antimicrobial activity against Staphylococcus aureus and Escherichia coli. The developed coatings therefore exhibit strong potential as bioactive, dual-functional protective layers for spinal screws, providing both osteoconductive and antimicrobial properties. Full article

Background/Objectives: This study aimed to compare the incidence, extent, and time to diagnosis of osteonecrosis of the femoral head (ONFH) between Femoral Neck System (FNS) and multiple cannulated screw (CS) fixation in patients with femoral neck fractures (FNFs) at a minimum follow-up of 24 months, as well as to identify factors associated with ONFH after FNS fixation. Methods: A retrospective cohort study was conducted at a single university hospital involving patients aged ≥18 years with isolated FNFs treated by closed reduction and internal fixation using either FNS or multiple CS. Reduction quality, fracture union, incidence and extent of ONFH (measured by Kerboul angle), and revision surgery due to ONFH or other causes were assessed as outcome measures. Logistic regression analyses were conducted to identify factors associated with ONFH after FNS fixation. Results: Eighty-seven patients were included, comprising 48 in the FNS group and 39 in the CS group. No significant differences were found between the groups in reduction quality, union rate, or time to union (p > 0.05 for all). The incidence of ONFH did not differ significantly between the FNS and CS groups (p = 0.314). However, the FNS group showed a significantly greater extent of ONFH (p = 0.031) and longer mean time to ONFH diagnosis (p = 0.001). No significant differences were observed in revision surgery rates due to ONFH (p = 1.000) or other causes (p = 0.624). Multivariate analysis identified fracture displacement (Garden classification stages III and IV) and poor reduction quality (“Broken S” by Lowell’s criteria) as significant predictors of ONFH after FNS fixation. Conclusions: ONFH following FNS fixation tended to exhibit a larger necrotic area and a delayed radiographic onset compared to CS fixation; however, the overall incidence and revision rates were comparable between implants. These differences may be due to initial fracture displacement and baseline severity, rather than the FNS implant itself. In the FNS group, the mean time to radiographic diagnosis of ONFH was 13.1 months, and initial fracture displacement and reduction quality were identified as risk factors for the development of ONFH following FNS fixation. Therefore, long-term and vigilant follow-up is essential after FNS fixation, particularly in patients with displaced fractures. Achieving optimal reduction quality and anatomical femoral neck alignment remains paramount to mitigating the risk of ONFH after FNS fixation. Full article

Biodegradable magnesium (Mg)-based implants represent a paradigm shift in orthopedic biomaterials, offering temporary mechanical support, inherent osteogenic bioactivity, and elimination of hardware removal surgery. These properties are particularly attractive for sports orthopedic applications, including anterior cruciate ligament (ACL) reconstruction, rotator cuff repair, meniscal fixation, and osteochondral fragment refixation, where young, active patients demand rapid return to function and where permanent metallic hardware poses long-term risks of stress shielding, imaging artifact, and reoperation. Despite extensive preclinical evidence demonstrating that Mg-based interference screws promote fibrocartilaginous enthesis regeneration, attenuate peri-tunnel bone loss, and achieve biomechanical fixation comparable to titanium, no human clinical trial has yet evaluated Mg fixation devices for soft-tissue reconstruction in sports medicine. Meanwhile, clinical fracture fixation data from over 468 patients across multiple trials and a meta-analysis confirm complication rates equivalent to those of titanium. This narrative review synthesizes the current evidence on Mg alloy design, surface engineering strategies, preclinical sports medicine applications, clinical translation in fracture fixation, imaging compatibility, and the remaining barriers to clinical adoption in sports orthopedic surgery. By mapping the translational gap between promising animal data and the absence of clinical sports medicine trials, this review aims to guide future research priorities and accelerate the pathway toward clinical application of Mg-based devices in sports orthopedics. Full article

Background and Objectives: This study aimed to investigate the biomechanical properties of different cephalomedullary fixation methods for osteoporotic femurs using a synthetic bone model. Materials and Methods: Lateral impact tests and axial cyclic loading tests were performed, and each test was divided into three groups: group 1 with one reconstruction screw, group 2 with two reconstruction screws, and group 3 without cephalomedullary fixation. To simulate a healed femoral shaft fracture, no osteotomy was performed on the specimens. Results: Groups 1 and 2 had significantly higher mean stiffness, ultimate failure load, and energy to failure in the lateral impact test compared to the native synthetic femur (p < 0.001 for all), while group 3 had significantly lower values in all outcomes (p < 0.05 for all). Groups 1 and 2 showed significantly higher average number of cycles, total load to failure, and initial axial stiffness in the axial cyclic incremental loading test compared to the native synthetic femur (p < 0.001 for all), whereas group 3 showed a significantly lower mean number of cycles and total load to failure (p < 0.001 for all). Conclusions: Under the specific test conditions of this intact synthetic bone model, cephalomedullary fixation with one or two reconstruction screws demonstrated superior relative mechanical stability compared to standard interlocking nails. Using two reconstruction screws provided the greatest biomechanical resistance to failure. In cases where inserting two reconstruction screws is technically challenging or infeasible, a single reconstruction screw may offer an acceptable biomechanical alternative to help prevent peri-implant fractures in healed or prophylactic settings. Intramedullary nailing without cephalomedullary fixation exhibited the lowest mechanical performance, suggesting a potential biomechanical vulnerability to peri-implant fractures under these test conditions. Full article

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

Background: Aging of the population increases the incidence of osteoporosis with atlantoaxial instability. Poor bone microarchitecture causes high rates of screw loosening, implant failure, and revision surgery, which remains a critical challenge for upper cervical surgery. Traditional atlantoaxial fixation is less effective in those with low bone mineral density, while thoracolumbar screw augmentation techniques are limited by the complex craniocervical anatomy. Methods: This review systematically summarizes the mainstream screw optimization strategies from a bioengineering perspective, including low-modulus alloy substrate modification, bionic threaded structural design, bioactive surface coatings, expandable screws, and cement-augmented cannulated screws. We compare the biomechanical anchorage performance, osteogenic capacity, and clinical complications of each technique. Results: Low-elastic-modulus titanium alloys reduce stress shielding; gradient multi-thread, bicortical, and CBT trajectory designs significantly improve anti-pullout stability; HA, tantalum, and composite extracellular matrix coatings promote osseointegration; and expandable screws and fenestrated cement screws can achieve reliable reinforcement. However, a narrow atlantoaxial space restricts the application of cement augmentation and expandable implants, and long-term, large-sample clinical evidence for the efficacy of novel screws is insufficient. Conclusion: Patient-specific porous degradable screws, which combine 3D-printed biomaterials, gradient alloys, and sustained-release bioactive coatings, represent a promising future research direction. This review provides theoretical support for the development of atlantoaxial internal fixation devices targeting elderly osteoporotic patients. Full article

Background: Digital workflows in implant prosthodontics continue to evolve, yet standardized protocols integrating clinician-driven abutment customization and peri-implant soft-tissue conditioning remain limited. This pilot study aimed to present and evaluate a progressive gingival digital workflow for cement-retained implant-supported restorations based on chairside adjustment of prefabricated abutments according to gingival maturation. Methods: A retrospective comparative study included 39 patients rehabilitated with 161 implants and followed for 24–48 months. The experimental group comprised 87 bone-level implants restored using a progressive digital workflow involving staged healing, chairside abutment customization, provisional tissue conditioning, and digital fabrication of definitive restorations. Outcomes were compared with 74 tissue-level implants restored using a conventional protocol with healing abutments and prefabricated prosthetic abutments. Clinical and radiographic outcomes included plaque index, bleeding on probing (BOP), peri-implant sulcus depth, marginal bone resorption, complications, and patient satisfaction. Results: Both groups demonstrated favorable clinical outcomes, with no significant differences in plaque index, gingival condition, BOP (28.74% vs. 21.62%), sulcus dimensions, or marginal bone resorption (11.49% vs. 12.16%) (p > 0.05). Logistic regression identified plaque accumulation, vestibular sulcus depth, and implant duration as predictors of BOP, whereas implant type was not associated with BOP or bone resorption. Patient satisfaction, assessed using a visual analog scale, was uniformly high. Most patients reported maximum scores across all domains, with only minor esthetic concerns reported by a few participants. No major prosthetic complications or screw loosening occurred during follow-up. Conclusions: The proposed workflow demonstrated favorable clinical performance and appears to be a feasible restorative approach. However, because implant design and restorative workflow differed simultaneously, findings should be interpreted cautiously. Larger prospective studies are needed to confirm these results. Full article