A study on biocompatibility and implant stability of 3D printed alumina/magnesium silicate composite ceramic bone screws.

BackgroundPercutaneous iliosacral screw fixation has become the gold standard for surgical stabilization of acute pelvic ring disruptions with unstable posterior pelvic injuries. Wound infection is uncommon owing to shorter operative time, reduced soft-tissue damage, less blood loss, and lower infection rates. Delayed sacroiliac joint infection after robot-assisted percutaneous iliosacral screw fixation is even rarer.Case presentation: We report a case of delayed sacroiliac joint infection after robot-assisted percutaneous iliosacral screw fixation for a tile type C2 pelvic fracture. A 43-years-old man developed recurrent low back pain and intermittent low-grade fever that occurred 10 months postoperatively and lasted 2 months. Symptoms temporarily improved with anti-inflammatory treatment but subsequently worsened, accompanied with chills and high fever (body temperature up to 39.0°C). Computed tomography revealed bone erosion and screw loosening, and inflammatory markers were elevated. The patient underwent open debridement and removal of the screws, followed by implantation of vancomycin- and gentamicin-loaded calcium sulfate beads. Cultures were negative; however, frozen section and pathology confirmed acute and chronic inflammatory infiltrations. The patient responded well to antibiotics and achieved full recovery.ConclusionsDelayed sacroiliac joint infection after robot-assisted percutaneous iliosacral screw fixation is a rare complication. Diagnosis can be challenging owing to the presence of atypical symptoms and negative cultures. Open debridement with removal of fixation and targeted antibiotic therapy can result in successful outcomes.

Severe varus knee osteoarthritis associated with medial tibial bone loss presents significant challenges during total knee arthroplasty, particularly in achieving stable alignment while preserving ligament balance. We report the case of a 68-year-old female who presented with severe right knee pain, progressive varus deformity, and inability to ambulate independently. Radiographic evaluation revealed tricompartmental osteoarthritis with collapse of the medial tibial plateau and significant coronal deformity. The patient underwent primary unconstrained cruciate-retaining total knee arthroplasty using a tibial stem extension combined with reconstruction of the medial tibial defect using autologous bone graft and screw fixation. Intraoperative assessment demonstrated intact posterior cruciate and collateral ligaments, allowing the use of a cruciate-retaining implant despite severe deformity. Postoperative radiographs confirmed restoration of mechanical alignment and stable fixation of the components. At one-year follow-up, the patient achieved satisfactory range of motion, pain relief, and functional improvement without evidence of loosening or instability. This case highlights that cruciate-retaining total knee arthroplasty with tibial stem support and bone grafting can be an effective and cost-efficient treatment option for severe varus knees with preserved ligament competence, avoiding the need for constrained implants.

Poly(lactic acid) (PLA)-based biocomposites incorporating collagen (COLL) and hydroxyapatite (HA) were produced via melt micro-compounding and subsequent injection molding. 1,4-phenylene diisocyanate (PDI) was employed as a compatibilizer, while poly(ethylene glycol) (PEG) was used as a plasticizer. The morphological, thermal, rheological, and mechanical properties, as well as surface wettability, degradation behavior, and cytotoxicity, were comprehensively evaluated. SEM and DSC analyses revealed the phase distribution and thermal transitions, while rheological measurements showed that PEG reduced melt viscosity by increasing chain mobility. Mechanical performance was evaluated using tensile, impact, and DMA tests on standard specimens, indicating that HA primarily enhanced stiffness (elastic modulus), whereas PEG improved toughness, resulting in higher impact strength. Biodegradable bone screw prototypes were produced with the same formulations and subjected to torsion, enzymatic degradation, and MTT cytotoxicity tests. Degradation results indicated that biocomposites containing PEG, collagen, and HA exhibited accelerated mass loss. Overall, the 70/20/10 PLA/COLL/HA/PEG/PDI formulation was more suitable for soft (trabecular) bone tissue, while the 70/10/20 PLA/COLL/HA/PDI formulation showed advantages for hard (cortical) bone tissue applications.

Unstable posterior pelvic ring injuries are carrying a significant mortality risk, and the gold standard treatment for this condition is percutaneous sacroiliac screw fixation. However, traditional methods for transiliac-transsacral screw placement involve numerous difficulties in the positioning of the screw channels. Although computer-assisted navigation can improve accuracy, its complexity and high-cost limit its widespread adoption. This study aimed to develop and implement a positioning method for transiliac-transsacral screw placement via computed tomography (CT) imaging. The proposed technique involves detailed manual tracing of anatomical structures from CT scans onto transparent overlays. This process, performed on sagittal planes, aims to delineate a “safe channel” within the cancellous bone of the sacrum, thereby avoiding sacral nerves, canals, and blood vessels. Proportional measurements derived from these tracings serve as references to guide intraoperative screw placement via standard radiography. A retrospective study of 12 patients with unstable posterior pelvic ring injuries demonstrated the practical applicability of this method. All procedures were performed by a single senior surgeon. Postoperative CT assessments according to the Gertzbein-Robbins scale indicated favorable screw placement accuracy, with no observed complications in this cohort. The study highlights that while computer-assisted navigation remains a superior option when available, this CT-based manual tracing technique offers a viable and safe alternative for settings in which access to advanced navigation systems is limited. Key limitations include the manual nature of the design, the reliance on consistent patient positioning, and the need for further prospective, large-scale, and multioperator studies to validate the reproducibility and long-term efficacy of this approach. A key prerequisite for this technique is achieving adequate reduction and ensuring the presence of a safe bony corridor. A significantly displaced bilateral pelvic fracture, which prevents the formation of a safe corridor, is considered a contraindication to this approach

Articular fractures require precise anatomical reduction and rigid fixation to heal appropriately. In veterinary cases that involve fracturing of the lateral humeral condyle, cortical bone screws inserted in lag fashion with Kirschner wire are the preferred method for surgical fixation. However, relatively high complication rates associated with cortical lag screws (CLSs) highlights the need to investigate alternate screw designs. Variable-pitch headless compression screws (VPHCSs) are unique as they advance beneath the cortical surface. Although the use of VPHCSs are widely utilised in human orthopaedics, the current use in veterinary orthopaedics is limited. This study aimed to evaluate the peak interfragmentary force (PIF) and area of compression (AOC) generated by a 3.5 mm self-tapping cortical screw placed in lag fashion and a 3.5 mm VPHCS inserted to four depths. PIF and AOC were measured using a pressure-sensitive film placed between two blocks of polyurethane foam (0.24 g/cm3), simulating a transverse fracture. CLSs were inserted by hand into predrilled 2.5 mm pilot holes. PIF and AOC were measured at full insertion. VPHCSs were placed into predrilled 2.5 mm pilot holes, followed by a 3.5 mm tapered countersink. The screw was inserted until the head was level with the surface. PIF and AOC were measured between the two blocks. The screw was continued until the head was at a depth of 2, 5, and 9 mm below the surface, and the PIF and AOC were measured again at each stage. There was no detectable difference in PIF and AOC between CLSs and VPHCSs countersunk to -2 mm (PIF-CLS: Mean = 12.886, SD = 2.370; 2 mm: Mean = 17.301, SD = 8.858, p = 0.319; AOC-CLS: Mean = 0.936, SD = 0.291; 2 mm: Mean = 0.925, SD = 0.447, p = 0.872). VPHCSs countersunk to -5 mm and -9 mm produced significantly greater PIF compared to CLSs (5 mm: Mean = 16.086, SD = 6.799, p = 0.002; 9 mm: Mean = 34.987, SD = 4.015, p < 0.001). VPHCSs countersunk to -5 and -9 mm produced significantly greater PIF and AOC compared to CLSs in this model. Further investigation is required to produce recommendations for clinical use.

The introduction of 3-dimensional printing has revolutionized orthopedic surgery, enabling patient-customized implants to address complex bone defects. However, ensuring reliable fixation remains a considerable challenge. Herein, we developed a finite element analysis (FEA)-based flow designed to evaluate implant fixation across various anatomical sites. We applied this flow to the pelvic region to validate its fixation strategies and optimize the design across different osteointegration stages: acute, pre-, and post-osteointegration. Effects of screw-fixation methods (short screws in the cancellous bone and long screws in the cortical bone) on patient outcomes were analyzed and validated using data from 2 patients. Predictive outcomes aligned closely with clinical results in terms of the location and timing of screw-fixation failure. The study findings affirm the potential of FEA to verify implant design and fixation strategies and to enhance surgical success rates through improved preoperative planning.

Routine augmentation of pedicle screws in standard clinical practice is performed using polymethylmethacrylate (PMMA) cement. However, owing to its high compressive strength and high Young's modulus, this material acts more as a stiffener in the spine than as a suitable replacement for compressed cancellous bone. Adjacent fractures caused by this represent a common clinical problem. A new experimental magnesium phosphate cement seems more suitable for this purpose, as it shows promising biomechanical properties and has been proven to be injectable via long cannulated systems. However, the application of this material has not yet been explored or quantified. Fenestrated pedicle screws were inserted into polyurethane bone blocks of different densities and augmented with experimental magnesium phosphate cement. This was followed by biomechanical testing in a realistic loading scenario. In addition, the injection force required for augmentation was quantified depending on the syringe type. Cement augmentation was possible in all bone blocks used and consistently had a positive effect on the biomechanical stability of fenestrated pedicle screws. The size of this effect varied depending on the density of the bone blocks used. No cutoff value could be identified at which augmentation should be performed. The novel experimental ready-to-use formulation of magnesium phosphate cement reliably enabled cement augmentation of fenestrated pedicle screws and consistently resulted in improved biomechanical stability. These findings suggest that a biocompatible and degradable bone cement with suitable biomechanical properties may represent a future alternative for spinal augmentation.

BackgroundThe anterior transpedicular cortical screw technique for the subaxial cervical spine represents a novel surgical fixation method for treating cervical spondylosis. Due to the complex anatomical structure of the cervical spine, screw placement presents certain technical challenges. Research on screw placement-related parameters will facilitate the widespread clinical application of this technique.ObjectiveThis study aimed to visualize and determine the optimal trajectory for placing cortical bone screws in the lower cervical spine (C3–C7) via an anterior approach, providing anatomical data for clinical application.MethodsSelect 100 healthy adult volunteers (50 males and 50 females)and perform continuous CT scans of their cervical spine with a layer thickness of 0.625 mm and a spacing of 0 mm. Use MIMICS21.0 software to establish a three-dimensional digital model of the lower cervical spine, and create a hollow screw model with an outer diameter of 2.8 mm and an inner diameter of 0.5 mm. Visualize the placement of screws at different segments from anterior to posterior through the vertebral body and pedicle. Screw position was adjusted to maximize cortical purchase within the pedicle without breach. Parameters including the distances to the midline and superior endplate of entry points, and lateral/cephalad angles of the screws were measured. All measurements were conducted in MIMICS21.0 software, and the same data was measured by two people and averaged to compare the differences between male and female, left and right sides of the same indicator data.ResultsThe entry points of all four segments of the lower cervical spine are located on the same side of the pedicle. The distance between the entry points and the mid sagittal line, as well as the vertical distance to the upper endplate of the same vertebra, are between 1.96 mm–2.62 mm and 1.30 mm–1.93 mm, respectively, showing a gradual increase from C3 to C5 and a gradual decrease from C5 to C7. There is no statistically significant difference between the left and right sides of each segment or between males and females; All screws of the four segments of the lower cervical spine need to be tilted outward and upward, with tilt angles between 24.27°–39.42° and 16.60°–18.57°, respectively. The tilt angles also show a gradual increase from C3 to C5 and a gradual decrease from C5 to C7, with no statistically significant differences between the left and right sides of each segment or between males and females.ConclusionIt is feasible to insert cortical pedicle screws via the anterior cervical approach, maximizing screw purchase on cortical bone. Compared to conventional screws, this method may facilitate easier insertion and better plate conformity.

IntroductionLocking screws typically provide more stable fixation than conventional cortical screws. However, the rigid connection between the locking screw head and plate hole can cause stress concentrations and lead to early failure under cyclic loading. This study aimed to compare the mechanical stability of a continuous (headless) locking screw with standard locking screws and cortical screws, either in a standard (flush with the bone) or in far cortical locking constructs, using biomechanical testing and finite element analysis (FEA).MethodsThe Trident Distal Radial Locking Plate (A-Plus Biotechnology Co., Ltd., Taiwan) was used to repair a simulated distal radial diaphysis fracture and was secured to the bone using different screw types. The fracture gap was bridged with the plate placed flush with the bone and with the plate offset from the bone surface by 4 mm (far cortical locking (FCL)). The constructs were subjected to static compression and cyclic axial loading tests to assess construct stiffness and yield load, as well as endurance and failure mechanisms under cyclic loading, while FEA was used to evaluate the von Mises stress distribution on the plates and screws.ResultsThe Group 3a (flush with bone, continuous locking screws) had a significantly higher yield load than Groups 2b (FCL with locking screws) and 3b (FCL with continuous locking screws) (p < 0.05). In addition, Group 1 (flush with bone, cortical screws) was found to be significantly stiffer than Groups 2b and 3b (p < 0.01). For the dynamic testing, Group 3a showed intermediate endurance and failed predominantly by screw pull-out, whereas Groups 1 and 2 primarily failed by plate deformation. The FEA results showed stress concentrations at the screw neck of the standard locking screws and around the threaded regions of the continuous locking screws.ConclusionContinuous locking screws placed flush with the bone had the greatest fixation strength of all configurations tested. However, using continuous locking screws in an FCL configuration may redirect stress to the threaded region of the screw neck, potentially increasing the risk of failure.

Purpose The purpose of this study is to investigate the potential of auxetic metamaterials, specifically Re-entrant and Re-entrant Triangular unit cell designs, in enhancing the performance of bone screws used in orthopedic surgeries. By leveraging their negative Poisson's ratio properties, these auxetic designs aim to improve screw-bone interfacial stability, reduce loosening and increase load-bearing capacity under shear and bending stresses. Through high-resolution 3D printing and mechanical testing, the study evaluates the effectiveness of auxetic bone screws compared to conventional designs, with the goal of advancing patient-specific, reliable orthopedic implants that enhance clinical outcomes and reduce long-term healthcare costs. Design/methodology/approach Auxetic bone screws were designed by integrating Re-entrant and Re-entrant Triangular unit cell geometries into the screw body to exploit negative Poisson's ratio behavior. High-resolution 3D printing was employed to fabricate the screws with precise geometrical accuracy, enabling reliable replication of complex auxetic structures. Mechanical performance was evaluated through shear and three-point bending tests, with conventional bone screws serving as controls. Comparative analysis focused on load-bearing capacity, deformation resistance and the influence of auxetic unit cell arrangement. This approach enabled systematic evaluation of auxetic design advantages for improving screw-bone fixation and orthopedic implant reliability. Findings The results demonstrated that auxetic bone screws, particularly those with Re-entrant Triangular unit cells, exhibited superior mechanical performance compared to conventional screws. They showed higher load-bearing capacity, enhanced deformation resistance and improved screw-bone interfacial stability under shear and bending loads. The auxetic structures' lateral expansion during loading increased contact with the surrounding bone, effectively reducing the likelihood of screw loosening. Additionally, the arrangement and geometry of unit cells significantly influenced performance, with optimized designs achieving the best outcomes. Originality/value This study is among the first to apply auxetic metamaterial concepts to bone screw design, offering a novel strategy to overcome the persistent problem of screw loosening in orthopedic implants. By integrating Re-entrant and Re-entrant Triangular auxetic unit cells, the research introduces designs that leverage negative Poisson's ratio behavior to actively improve screw-bone fixation under mechanical loading. The combination of high-resolution 3D printing with experimental mechanical testing provides new insights into how auxetic geometries influence implant stability. This original approach highlights the potential for patient-specific, mechanically superior and sustainable orthopedic implants beyond traditional screw designs.

Immunomodulatory-osteogenic dual-functional nanofibers augment screw anchorage in osteoporotic bone

Scaphoid fractures are the most common carpal bone injuries and remain clinically challenging due to retrograde vascular supply and risks of nonunion, malunion, and avascular necrosis. Surgical fixation is often preferred over conservative management for unstable, displaced, or proximal fractures, offering faster union and earlier functional recovery. This review outlines current fixation techniques, including Herbert and headless compression screws, plate fixation, and newer minimally invasive or hybrid methods. Headless compression screws provide interfragmentary compression, while plate fixation is particularly useful in complex or comminuted cases, though hardware irritation is a common drawback. Arthroscopy-assisted fixation reduces soft-tissue disruption and preserves vascularity, showing promising outcomes but requiring further long-term validation. Adjunctive methods such as bone grafting and emerging biomaterials, including bioabsorbable and allogeneic cortical bone screws, expand treatment options and may reduce complications related to metal hardware. Across studies, surgical fixation consistently demonstrates higher and faster union rates, improved early grip strength, and accelerated return to activity, particularly in high-demand populations. However, the literature is limited by small sample sizes, heterogeneous outcome measures, and a lack of long-term data. Future high-quality randomized controlled trials are needed to establish clearer evidence-based guidelines for optimal fixation strategies in scaphoid fracture management.

Biomechanical stability and pedicle screw loosening.

Introduction: Orbital floor fractures are common facial injuries that often result in functional and aesthetic impairment. Open Reduction and Internal Fixation (ORIF) using various materials, like Poly Lactic-Co-glycolic Acid (PLGA) mesh and titanium mesh, have been employed to repair these fractures. Need of the study: Recent advancements in hybrid bone mesh, including bioactive materials or elements to promote fracture healing, show significant promise. One such innovation involves using biodegradable PLGA material to create a bone screw mesh, which has demonstrated benefits for fracture healing and has gained interest recently. These developments aim to enhance treatment plans for patients by offering superior aesthetic and functional properties. However, evidence comparing their functional and aesthetic outcomes is limited. Aim: The present randomised controlled trial aims to compare and evaluate the functional and aesthetic outcomes of ORIF using PLGA mesh and titanium mesh in patients with orbital floor fractures. Materials and Methods: A randomised single-blinded controlled trial will be conducted at Siddharth Gupta Memorial Cancer Hospital (AVBRH), Datta Meghe Institute of Higher Education and Research, Sawangi, Wardha, Maharashtra, India, from September 2024 to December 2025. A total of 12 patients presenting with orbital floor fractures will be included and two parallel groups, A and B, will be allocated by randomisation and they undergo ORIF using either or titanium mesh (Group A- Control group) or PLGA mesh (Group B-Experimental group). Functional outcomes, including diplopia, enophthalmos, ocular motility, and infraorbital nerve function, will be assessed using standardised clinical measures. Aesthetic outcomes will be evaluated based on facial symmetry, globe position, and patient satisfaction using validated scoring systems. Followup assessments will be conducted at regular intervals of 10-15 days. An unpaired t-test will be applied for intergroup comparison, and a p-value of less than 0.05 will be considered statistically significant.

Precision fabrication and performance tailoring of magnesium bone screws via picosecond laser milling

To elucidate the retraction effectiveness of extra-alveolar mandibular buccal shelf (MBS) bone screws anchorage relative to the presence of mandibular third molars and ANB angle in Class III patients. This retrospective study included 45 patients (mean age = 22.2 ± 6.7 years) treated with bilateral MBS stainless steel bone screws (2 × 12 mm). Patients were subgrouped based on mandibular third molar status and ANB angle (≤-2° vs > -2°). Pretreatment and posttreatment cephalograms were superimposed and analyzed. Statistical tests included analysis of variance, paired and independent t-tests, and linear regression. Mean retraction of mandibular first molars and incisors was 1.86 ± 1.36 mm and 2.89 ± 1.64 mm, respectively, over an average of 9.0 months. Retraction ≥ 3 mm was significantly associated with treatment durations ≥ 12 months (P < .001). No significant differences in retraction outcomes were found among third molar subgroups. The severe malocclusion group (ANB ≤ -2°) showed greater molar retraction and overjet increase. A moderate positive correlation was found between molar crown retraction and retraction duration (R2 = 0.282, P < .001). MBS bone screws provide effective, minimally invasive anchorage for mandibular whole-arch retraction in Class III patients. Treatment outcomes are not hindered by third molars in adolescents, and longer retraction duration enhances distal movement.

Background. The widespread introduction of computer planning and 3D printing technologies has opened a new era in the reconstruction of pelvic defects, which allows to ensure maximum anatomical compliance, especially in defects in several segments of the pelvis. Optimization of the implant fit to the bone edges reduces the risk of instability and overloads at the contact points, which improves the long-term stability of the structure. The purpose was to determine the features of stress distribution in human pelvis models with endoprostheses of different designs after resection of the hip socket due to oncological diseases. Materials and methods. A basic finite element model of the human pelvic girdle with femurs was developed, on which 3 options for arthroplasty of the left hip joint were created in conditions of a post-resection segmental defect of the pelvic bones, which violates the integrity of the anterior pelvic ring: 1 — replacement using an endoprosthesis without replacing the defect; 2 — arthroplasty using an endoprosthesis with restoration of the integrity of the pelvic ring; 3 — a model without defects of the pelvic bones with a standard hip joint replacement. The models were loaded with a vertical distributed force of 540 N. The action of m.gluteus medius was simulated with a force of 1150 N and m.gluteus minimus had rigid fixation. Results. When using an endoprosthesis of the hip socket without restoring the integrity of the pelvic ring, the maximum stress level was determined in the superior iliac spine and did not exceed 21.6 MPa. The most stressed element of this type of endoprosthesis is the screws in the iliac flange — 182.3 MPa. At the same time, the stress in the iliac flange itself was observed at a rather low level of 29.0 MPa. The reason for this stress distribution is the cantilevered version of the cup attachment. When using an endoprosthesis that restores the integrity of the pelvic ring, a significant increase in the stress level was observed: in the lesser sciatic notch under the iliac flange of the endoprosthesis — to 79.6 MPa and to 69.0 MPa in the greater sciatic notch. The stress level in the right (intact) pubic bone increased almost 8 times — 33.5 MPa, which is a consequence of the fact that it is the second fixation point of the endoprosthesis. The maximum stress level was determined for the screws in the contralateral pubic bone — 113.4 MPa. But due to the presence of the second attachment point (on the pubic bone), the stresses in the iliac flange screws do not exceed 86.8 MPa. Conclusions. The use of the endoprosthesis without restoring the integrity of the pelvic ring leads to a significant decrease in stresses in the bone elements on the prosthetic side, although it is accompanied by an increase in stresses on the iliac flange screws. Arthroplasty with restoration of the pelvic ring causes a significant increase in stresses in the prosthesis fixation zones, especially in the area of the intact pubic bone, which becomes the second supporting link of the structure. An increase in stresses in the elements of the endoprosthesis and the bone model is associated with the high rigidity and mass of titanium components. According to the criteria of minimizing stresses in the bones and in the endoprosthesis, the option without restoration of the pelvic ring is more favorable.

Introduction The complexity of treating intra-articular fractures in children is due to the anatomical features of the joint, its biomechanics, and the tendency to develop post-traumatic arthritis. This necessitates a detailed study of the structural organization of all elements of the joint synovial environment. The aim of this study was to evaluate, using an experimental model, the severity of structural changes in the synovial membrane of the carpal joint during osteosynthesis of intra-articular metaphyseal fractures with titanium screws. Materials and Methods The study was performed on six outbred male lambs (46.1 ± 3.0 days old, weighing 15.7 ± 2.0 kg). An oblique intra-articular metaphyseal fracture of the radius on the right limb was modeled. Fracture fixation was performed with two cannulated cancellous bone screws made of Ti6AL4V titanium. The experimental periods were 120 ( n = 3) and 365 ( n = 3) days after surgery. Histomorphometric analysis of the synovial membrane was performed using an AxioScope.A1 microscope and Zenblue software (CarlZeissMicroImagingGmbH, Germany). The synovium of the contralateral joint served as a control. Results In the control joint, fibroblast-like synoviocytes predominated in the synovial membrane lining layer; no signs of synovitis were detected. After 13.5 months, a decrease in lining layer thickness ( p = 0.0326) and synoviocyte density ( p = 0.0009) was noted. In the experimental joint, mild synovitis, hyperplasia of the lining layer, increased synoviocyte density and macrophage-like synoviocyte representation (more than 50 % per field of view), formation of synovial villi, and the presence of focal and diffuse lymphohistiocytic infiltrates were detected after 120 days. After 365 days, signs of synovitis were absent, fibroblast-like synoviocytes predominated in the lining layer; elevated synoviocyte density values persisted ( p = 0.0141), and lining layer thickness values were comparable to the control ( p = 0.1301). Discussion Non-bioresorbable fixators used for osteosynthesis of intra-articular fractures can cause a number of complications, including infection, pain, and arthritis. It was established that macrophage and fibroblastic synoviocytes perform various pro- and anti-inflammatory functions and can both prevent inflammation by forming an anti-inflammatory barrier and contribute to the development of synovitis. Conclusion Osteosynthesis of intra-articular metaepiphyseal fractures of the distal articular end of the radius in lambs using titanium screws provoke mild synovitis after 120 days of the experiment. This synovitis was characterized by thickening of the lining layer, an increase in the numerical density of synoviocytes and in macrophage synoviocytes, and the presence of a lymphohistiocytic infiltrate. By the end of the experiment, the synovial membrane inflammation revered, and histological signs of synovitis were absent.

While dimensional accuracy and surface characteristics of human orthopedic implants are extensively regulated and studied, comparable evaluations of veterinary orthopedic implants are limited. This study aimed to assess the dimensional conformity and surface finish of commercially available veterinary cortical bone screws relative to established engineering standards. Seventy-three commercially available 2.0 mm veterinary cortical bone screws from five anonymized manufacturers were analyzed using high-magnification optical microscopy. Dimensional parameters assessed included screw length, major diameter, minor diameter, thread pitch, and combined thread angle (α + β). Measurements were calibrated using a certified micrometer scale. Dimensional conformity was evaluated using a unilateral tolerance framework based on ISO 5835 low-quality limits. Surface finish was assessed using a semi-quantitative grading system under standardized magnification. Most screws exhibited dimensional deviations outside the defined tolerance limits. Eighty percent of screws were outside tolerance for length, 78% for major diameter, 77% for minor diameter, 98.6% for pitch, and 60% for combined thread angle. Surface finish was classified as unacceptable in 40% of screws. Tolerance deviations were observed across all manufacturers, with no single manufacturer accounting for the majority of non-conforming screws. The findings demonstrate substantial dimensional variability and surface defects in commercially available veterinary cortical bone screws. These deviations may adversely affect screw biomechanics and the bone-implant interface, indicating suboptimal manufacturing quality. The absence of regulatory oversight for veterinary implants highlights the need for improved quality control standards to ensure consistent and reliable implant performance.