Mechanical Fixation Research Articles

The novel magnesium–titanium hybrid cannulated screws for the treatment of vertical femoral neck fractures: Biomechanical evaluation

BackgroundConventional cannulated screws are commonly used for internal fixation in the treatment of vertical femoral neck fractures. However, the noticeably high rates of undesirable outcomes such as nonunion, malunion, avascular necrosis, and fixation failure still troubled the patients and surgeons. It is urgent to develop new cannulated screws to improve the above clinical problems. The purpose of this study was to design a novel magnesium-titanium hybrid cannulated screw and to further evaluate its biomechanical performance for the treatment of vertical femoral neck fractures. MethodsA novel magnesium-titanium hybrid cannulated screw was designed, and the conventional titanium cannulated screw was also modeled. The finite element models for vertical femoral neck fractures with magnesium-titanium hybrid cannulated screws and conventional cannulated screws were respectively established. The hip joint contact force during walking gait calculated by a subject-specific musculoskeletal multibody dynamics model, was used as loads and boundary conditions for both finite element models. The stress and displacement distributions of the cannulated screws and the femur, the micromotion of the fracture surfaces of the femoral neck, and the overall stiffness were calculated and analyzed using finite element models. The biomechanical performance of the Magnesium–Titanium hybrid cannulated screws was evaluated. ResultsThe maximum stresses of the magnesium-titanium hybrid cannulated screws and the conventional cannulated screws were 451.5 ​MPa and 476.8 ​MPa, respectively. The maximum stresses of the femur with the above different cannulated screws were 140.3 ​MPa and 164.8 ​MPa, respectively. The maximum displacement of the femur with the hybrid cannulated screws was 6.260 ​mm, lower than the femur with the conventional cannulated screws, which was 7.125 ​mm. The tangential micromotions in the two orthogonal directions at the fracture surface of the femoral neck with the magnesium-titanium hybrid cannulated screws were comparable to those with the conventional cannulated screws. The overall stiffness of the magnesium-titanium hybrid cannulated screw system was 490.17 ​N/mm, higher than that of the conventional cannulated screw system, which was 433.92 ​N/mm. ConclusionThe magnesium-titanium hybrid cannulated screw had superior mechanical strength and fixation stability for the treatment of the vertical femoral neck fractures, compared with those of the conventional cannulated screw, indicating that the magnesium-titanium hybrid cannulated screw has great potential as a new fixation strategy in future clinical applications.The translational potential of this article: This study highlights an innovative design of the magnesium-titanium hybrid cannulated screw for the treatment of vertical femoral neck fractures. The novel magnesium-titanium hybrid cannulated screw not only to provide sufficient mechanical strength and fixation stability but also to contribute to the promotion of fracture healing, which could provide a better treatment for the vertical femoral neck fractures, beneficially reducing the incidence of nonunion and reoperation rates.

Analysis of the Mechanical Behavior of Porcine Graft Fixation in a Polyurethane Block Using a 3D-printed PLA Interference Screw.

Objective The interest in using 3D printing in the healthcare field has grown over the years, given its advantages and potential in the rapid manufacturing of personalized devices and implants with complex geometries. Thus, the aim of the present study was to compare the mechanical fixation behavior of a 3D-printed interference screw, produced by fused deposition modeling of polylactic acid (PLA) filament, with that of a titanium interference screw. Methods Eight deep flexor porcine tendons, approximately 8 mm wide and 9 cm long, were used as graft and fixed to a 40 pounds-per-cubic-foot (PCF) polyurethane block at each of its extremities. One group was fixed only with titanium interference screws (group 1) and the other only with 3D-printed PLA screws (BR 20 2021 018283-6 U2) (group 2). The tests were conducted using an EMIC DL 10000 electromechanical universal testing machine in axial traction mode. Results Group 1 (titanium) obtained peak force of 200 ± 7 N, with mean graft deformation of 8 ± 2 mm, and group 2 (PLA) obtained peak force of 300 ± 30 N, and mean graft deformation of 7 ± 3 mm. Both the titanium and PLA screws provided good graft fixation in the polyurethane block, with no slippage or apparent deformation. In all the samples, the test culminated in graft rupture, with around 20 mm of deformation in relation to the initial length. Conclusion The 3D-printed PLA screw provided good fixation, similar to that of its titanium counterpart, producing satisfactory and promising results.

Investigation of the Influence of Roughness and Dental Implant Design on Primary Stability via Analysis of Insertion Torque and Implant Stability Quotient: An In Vitro Study.

In the placement of dental implants, the primary fixation between the dental implant and the bone is of great importance and corresponds to compressive mechanical fixation that aims to prevent micromovement of the implant. The aim of this research was to determine the role of roughness and the type of dental implant (tissue-level or bone-level) in implant stability, measured using resonance frequency analysis (RFA) and insertion torque (IT). We analyzed 234 titanium dental implants, placed in fresh calf ribs, at the half-tissue level and half-bone level. The implant surface was subjected to grit-blasting treatments with alumina particles of 120, 300, and 600 μm at a projection pressure of 2.5 bar, resulting in three types of roughness. Roughness was determined via optical interferometry. The wettability of the surfaces was also determined. Implant stability was measured using a high-precision torquemeter to obtain IT, and RFA was used to determine the implant stability quotient (ISQ). The results show that rough surfaces with Sa values of 0.5 to 4 μm do not affect the primary stability. However, the type of implant is important; bone-level implants obtained the highest primary stability values. A good correlation between the primary stability values obtained via IT and ISQ was demonstrated. New in vivo studies are necessary to know whether these results can be maintained in the long term.

Anterior Cruciate Ligament and Anterolateral Ligament Reconstruction With Pedicular Hamstrings Tendon Graft, Single-Strand Gracilis for ALL and Single Blind Femoral Tunnel

Combined anterior cruciate ligament and anterolateral ligament reconstruction (ACL+ALL r) is a common procedure to treat rotational instability and to prevent ACL graft failure. Recent studies have described numerous combined reconstruction techniques to obtain the most anatomical procedure with the least graft donor site morbidity and the best clinical results.Hamstring (HG) grafts are the most popular graft in literature. Leaving pedicle HG can preserve enough blood supply to improve tendon-bone healing with additional mechanical fixation of the graft on the tibial side. A single femoral tunnel reduces bone loss and prevents convergence of 2 femoral tunnels. We describe an original ACL and ALL reconstruction technique that preserves hamstring tibial insertion with a single blind femoral tunnel.

Intussusception Allograft Prosthetic Composites in Total Hip Arthroplasty: A Salvage Operation for Extensive Femoral Bone Loss

BackgroundAllograft prosthetic composites (APCs) have been used to perform revision total hip arthroplasty (THA) for massive femoral bone loss or deformity. Intussusception, or “telescoping”, APC techniques have been proposed to enhance the contact area of this interface and provide superior mechanical fixation over conventional methods. The purpose of this study is to present to our knowledge, the largest series of telescoping APC THAs, along with surgical technique details and midterm (average 5-10 years) clinical results. MethodsBetween 1994 and 2015, 46 revision THAs performed with proximal femoral telescoping APCs were retrospectively reviewed at a single institution. Overall survival, reoperation-free survival, and construct survival rates were calculated via Kaplan-Meier methods. In addition, radiographic analyses were performed to evaluate for component loosening, union at the APC-host interface, and resorption of the allograft. ResultsAt 10 years, the overall patient survival was 58%, reoperation-free survival was 76%, and construct survival was 95%. Reoperation was performed in 20% (n = 9) and only 2 constructs required resection. Radiographic analyses performed at latest follow-up revealed no instances of radiographic femoral stem loosening, an 86% union rate at the APC-host site, 23% with signs of some allograft resorption, and a 54% trochanteric union. The mean postoperative Harris hip score was 71 points (range, 46-100). ConclusionTelescoping APCs are technically demanding, but provide reliable mechanical fixation for the reconstructing of large proximal femoral bone deficits in revision THA with excellent construct survivorship, acceptable reoperation rates, and good clinical outcomes. Level of EvidenceIV.

Biomechanical evaluation of a novel biomimetic artificial intervertebral disc in canine cervical cadaveric spines.

Cervical disc replacement (CDR) aims to restore motion of the treated level to reduce the risk of adjacent segment disease (ASD) compared with spinal fusion. However, first-generation articulating devices are unable to mimic the complex deformation kinematics of a natural disc. Thus, a biomimetic artificial intervertebral CDR (bioAID), containing a hydroxyethylmethacrylate (HEMA)-sodium methacrylate (NaMA) hydrogel core representing the nucleus pulposus, an ultra-high-molecular-weight-polyethylene fiber jacket as annulus fibrosus, and titanium endplates with pins for primary mechanical fixation, was developed. To assess the initial biomechanical effect of the bioAID on the kinematic behavior of the canine spine, an ex vivo biomechanical study in 6-degrees-of-freedom was performed. A canine cadaveric biomechanical study. Six cadaveric canine specimens (C3-C6) were tested in flexion-extension (FE), lateral bending (LB) axial rotation (AR) using a spine tester in three conditions: intact, after C4-C5 disc replacement with bioAID, and after C4-C5 interbody fusion. A hybrid protocol was used where first the intact spines were subjected to a pure moment of ±1Nm, whereafter the treated spines were subjected to the full range of motion (ROM) of the intact condition. 3D segmental motions at all levels were measured while recording the reaction torsion. Biomechanical parameters studied included ROM, neutral zone (NZ), and intradiscal pressure (IDP) at the adjacent cranial level (C3-C4). The bioAID retained the sigmoid shape of the moment-rotation curves with a NZ similar to the intact condition in LB and FE. Additionally, the normalized ROMs at the bioAID-treated level were statistically equivalent to intact during FE and AR while slightly decreased in LB. At the two adjacent levels, ROMs showed similar values for the intact compared to the bioAID for FE and AR and an increase in LB. In contrast, levels adjacent to the fused segment showed an increased motion in FE and LB as compensation for the loss of motion at the treated level. The IDP at the adjacent C3-C4 level after implantation of bioAID was close to intact values. After fusion, increased IDP was found compared with intact but did not reach statistical significance. This study indicates that the bioAID can mimic the kinematic behavior of the replaced intervertebral disc and preserves that for the adjacent levels better than fusion. As a result, CDR using the novel bioAID is a promising alternative treatment for replacing severely degenerated intervertebral discs.

Improving the Biological Properties of UHMWPE Biocomposite for Orthopedic Applications.

Bone plates are essential for bone fracture healing because they modify the biomechanical microenvironment at the fracture site to provide the necessary mechanical fixation for fracture fragments. The objective of this study was to determine cell availability, antibacterial activity, and wettability through a contact angle test. However, biocomposites that involve UHMWPE reinforced with n-HA and n-TiO2 particles at different fractions (0, 1.5, 2.5, 3.5, and 4.5%) and 5% from carbon and Kevlar fibers were fabricated by hot pressing technique. In vitro studies revealed good cell viability on the surface of the hybrid biocomposite even after 72 hr. The UHMEPE nanocomposite reinforced with carbon showed better cell attachment for fibroblasts than other UHMWPE nanocomposite materials reinforced with Kevlar fiber. The results of the contact angle measurements indicated that the incorporation of nanoparticles and the fiber reinforcement increased the wettability due to the hydrophilic character of nanobiocomposite, and also (UHMWPE-4.5% wt. TiO2-CF) biocomposite was the best wettability (∼48% as compared to neat UHMWPE). Antibacterial experiments involving Gram-positive bacteria, Staphylococcus aureus, confirm excellent bactericidal property for (UHMWPE-4.5% wt. TiO2-CF) biocomposite. Thermal analysis of the produced nanocomposites revealed that they had higher melting and crystallinity temperatures than pure UHMWPE.

Investigation of Compression and Hardness for UHMWPE Bio-composites as Internal Bone Plate Fixation

Bone plates are essential for bone fracture healing because they modify the biomechanical microenvironment at the fracture site to provide the necessary mechanical fixation for fracture fragments. This paper addresses the use of composite bone plates in healing long-bone fractures such as transverse fractures of the femur. However, stress shielding in the bone due to metal plates can be reduced by designing implants with Bio-composites that involve Ultra high molecular polyethylene reinforced (UHMWPE) with Nano hydroxyapatite (n-HA) and Nano titanium dioxide (n-TiO2) particles at different weight fraction (0,1.5,2.5,3.5and 4. 5%) and 5% of carbon and Kevlar fibers. FRIT spectrum was used to identify the incorporation between the matrix and Nano particles, and the shifting in main peaks confirmed the good cross-linking within the composite structure. The specimens thus prepared were subjected to a compression test, hardness test, and density. The results indicated that UHMWPE+4.5%n-HA+CF hybrid biocomposite has the highest compressive strength and hardness properties. In contrast, UHMWPE+4.5%TiO2+CF has the highest density, which increased with increasing percentages of weight fraction of Nano-particles, where the compression strength 53 MPa, hardness property ranges 65.6 shore D, and density 1.09 (g/cm3). According to the current study's findings, it is possible to create bio-composites as internal fixation device with improved performance by placing different fiber reinforcements.

Research Progress on Antibacterial Coatings for Preventing Implant-Related Infection in Fractures: A Literature Review

Implant-related infection is a difficult problem in orthopaedics as it not only leads to failure in internal fixation, but also increases the financial burden and perioperative risk on patients. In the past, orthopaedic implants were designed as mechanical fixation devices simply to maintain mechanical and biological properties, not to regulate the surrounding biological microenvironment. More recently, antimicrobial biocoatings have been incorporated into orthopaedic implants to prevent and treat implant-related infections through the modulation of the local environment. This article reviews the application of orthopaedic-implant biocoating in the prevention of implant-caused infection. Although there are many candidate coatings, they are still in the preclinical testing stage, and thus additional research by biomaterials and clinicians is necessary to identify the ideal implant coatings for patients who require fracture surgery.

OC-070 A NOVEL SELF-GRIPPING LONG-TERM RESORBABLE MESH PROVIDING TEMPORARY SUPPORT FOR PRIMARY VENTRAL AND INCISIONAL HERNIA

Abstract Medtronic recently developed a novel synthetic fully long-term resorbable self-gripping mesh to reinforce soft tissue where weakness exists during ventral hernia repair procedures. This resorbable mesh is a macroporous, knitted, poly-L-lactide, poly-trimethylene carbonate copolymer monofilament mesh with the ProGrip™ technology. The biocompatibility profile of the mesh has been extensively established and documented. No systemic nor local adverse reactions have been observed from implantation to complete resorption and metabolization of the mesh in a subcutaneous implantation preclinical rabbit model. Its performance was evaluated at 20 weeks using a modified published preclinical porcine model of hernia repair (Martin, 2013; Deeken, 2013). Histologic examination of the implantation sites confirmed that this novel mesh was well tolerated and led to new extracellular collagen matrix formation. The burst strength of the hernia repair sites reinforced with the new mesh was statistically equivalent to the one of the native abdominal walls. Currently marketed ProGrip™ meshes have been clinically and successfully used with less mechanical fixation devices than non-self-gripping meshes (Chastan, 2009; Rangwani, 2021). The new self-gripping long-term resorbable mesh fixation performance was demonstrated to be statistically equivalent to the one of ProGrip™ Self-Gripping Polyester Mesh both in ex-vivo testing and in an in vivo porcine model. This should support the ease-of-use feature of the mesh with a limited need for additional mechanical fixation, which will likely be associated with a shorter surgical time. The preclinical tests of the self-gripping resorbable mesh are compelling enough to make it a new mesh candidate for future clinical use.

Finite Element Analysis for First Metatarsophalangeal Joint Arthrodesis Demonstrates Reduction in Stress Across Bio-Integrative Fixation Over Traditional Metal Fixation

Category: Midfoot/Forefoot; Bunion Introduction/Purpose: During each step-in gait, the first metatarsophalangeal joint (MTPJ) is stressed by 90% of body weight, while loading the metatarsal head and base with up to 29% (228N/80Kg patient) of body weight (188N) during each foot push-off. To withstand these high mechanical forces, a successful fusion is dependent on joint preparation and rigid fixation. In this study we assessed a novel bio-integrative fiber-reinforced screw and nail construct. This material technology may provide improved mechanical fixation profile through its high flexural strength and flexural modulus that is closely matched to that of cortical bone. Finite Element Analysis (FEA) was performed to evaluate the mechanical strength and stress concentrations acting on the 1st MTPJ fusion following the use of these implants, compared to conventional metal fixation. Methods: CT-based FEA of the 1st MTPJ fusion fixed by two fixation methods was simulated for mechanical strength and stress concentrations acting on the surrounding cortical bone. The 1st MTPJ of an adult male weighing 80kg was segmented from a left foot CT scan (120 KVP, SL 1mm) and was incorporated in a 3-dimensional CAD model. Bio-integrative fiber-reinforced 4.0mm partially threaded headless compression screw, and a 3.0mm fiber-reinforced cannulated nail were inserted in this computational model in crossed fashion (Fig. 1A). The bio-integrative implants are composed of continuous reinforcing mineral fibers (50% w/w), comprised of elements found in native bone and bound together by a degradable polymer [poly (L-lactide-co- D,L-lactide), PLDLA]. Two 4.0mm partially threaded headless titanium screws were inserted in similar trajectories and served as control (Fig. 1B). The FEA algorithm was based on published known forces acting on the first ray during push-off. Post-processing was performed on FEA results. Results: The relative displacement between the Metatarsal and Phalangeal heads upon simulated loading was 1.6mm for metal fixation and 0.2mm for the fiber-reinforced bio-integrative fixation, demonstrating this technology to be mechanically stable at least as conventional metal fixation. In both models, the Von-Mises maximum stresses were found between the implant thread and shank. However, maximum localized stresses in cortical bone regions interacting with the metal implants were substantially higher (up to 8 times) compared to the bio-integrative implant-bone interactions. Moreover, stresses in the implant body were remarkably higher with metal implants compared to bio-integrative fixation (Fig. 1C, D&E). These results indicate that for physiological loading conditions applied on the 1st MTPJ, the use of bio-integrative fixation construct may reduce stress concentrations at the implant-cortical bone interface. Conclusion: FEA results indicate that bio-integrative screw-nail construct provides equivalent mechanical fixation strength to metal fixation, while resulting in lower bone-implant stress concentrations. The closely matched flexural modulus of the bio- integrative material to that of cortical bone, decreases implant-bone resistance level and the probability of bone/implant failure and risk for implant loosening, all common complications in foot and ankle surgery. This study demonstrates a new methodology of CT-FEA for the evaluation of 1st MTPJ fusion arthrodesis and suggests the bio-integrative screw-nail combination as an alternative to traditional metal fixation. This model is currently being investigated in an ongoing clinical series.

Определение конгруэнтности стандартного полусферического вертлужного компонента и посттравматически деформированной вертлужной впадины при первичном эндопротезировании тазобедренного сустава (экспериментальное исследование)

Introduction An original ASPID classification was developed for primary total hip arthroplasty in the presence of post-traumatic acetabular deformity at the Vreden National Medical Research Centre for Traumatology and Orthopaedics. We aimed to explore how the extent of displacement and localization of acetabular deformity as classified by the original ASPID grading system can affect the coverage area of the acetabular component. The purpose of the study was to determine the congruence of the standard hemispherical acetabular component and the post-traumatic acetabular deformity in the experiment. Material and methods Computer 3D models of 92 post-traumatic acetabulums were formed, followed by simulated implantation of a standard hemisphere of the appropriate size in compliance with permissible values of the spatial orientation of the acetabular cup in total hip replacement. The congruence of the deformed acetabulum and the standard hemisphere of the corresponding size was determined with simulated implantation. Formula for the acetabular deformity was determined for each case using the original classification. With formula identified for each acetabular deformity and the magnitude of congruence, the data were compared to determine the relationship between congruence, bone displacement and the extent of bone displacement. Results The mean congruence value in the group was 59.5 ± 16.83 %. The sum of the scores A+S+P+I+D was compared with the percentage of congruence. The statistical analysis showed that the congruence of the hemispherical acetabular component and the post-traumatic acetabulum was less than 70% with a sum of parameters greater than four. The continuation of the study will allow for a more global analysis and identification of more patterns to improve surgical approaches to primary total hip arthroplasty in specific cases. Conclusion Screws can be recommended for reliable primary mechanical fixation of the pelvic component in target patients, and cavitary bone defects can be repaired with autobone chips to allow greater congruence at the bone-implant interface.

Surface modifications to promote the osteoconductivity of ultra-high-molecular-weight-polyethylene fabrics for a novel biomimetic artificial disc prosthesis: An in vitro study.

A novel biomimetic artificial intervertebral disc (bioAID) for the cervical spine was developed, containing a hydrogel core representing the nucleus pulposus, an UHMWPE fiber jacket as annulus fibrosis, and titanium endplates with pins for mechanical fixation. Osseointegration of the UHMWPE fibers to adjacent bone structures is required to achieve proper biomimetic behavior and to provide long-term stability. Therefore, the aim of this study was to assess the osteoconductivity of several surface modifications of UHMWPE fabrics, 2D weft-knitted, using non-treated UHMWPE fibers (N), plasma treated UHMWPE fibers (PT), 10% hydroxy apatite (HA) loaded UHMWPE fibers (10%HA), plasma treated 10%HA UHMWPE fibers (PT-10%HA), 15%HA loaded UHMWPE fibers (15%HA) and plasma treated 15%HA UHMWPE fibers (PT-15%HA). Scanning electron microscopy (SEM) was used for surface characterization. Biological effects were assessed by evaluating initial cell attachment (SEM, DNA content), metabolic activity (PrestoBlue assay), proliferation, differentiation (alkaline phosphatase activity) and mineralization (energy dispersive x-ray, EDX analysis) using human bone marrow stromal cells. Plasma treated samples showed increased initial cell attachment, indicating the importance of hydrophilicity for cell attachment. However, incorporation only of HA or plasma treatment alone was not sufficient to result in upregulated alkaline phosphatase activity (ALP) activity. Combining HA loaded fibers with plasma treatment showed a combined effect, leading to increased cell attachment and upregulated ALP activity. Based on these results, combination of HA loaded UHMWPE fibers and plasma treatment provided the most promising fabric surface for facilitating bone ingrowth.

Formation mechanism of plant diversity in mechanical sand‐control technique‐implemented dunes in China

AbstractAlthough the influence of mechanical sand control techniques on vegetation on degraded sand dunes has received much attention for a long time, our understanding of the underlying processes of plant community formation is not yet strong. Analyses of trends in the turnover and nestedness components of beta diversity can be informative of the process of response to sand dune stabilization. In this study, we applied a field investigation of sand dunes at different stabilization stages in northern China. We then used Baselga's method to calculate total beta diversity and partition it into spatial turnover and nestedness to clarify the underlying community change processes. Our study indicated that the implementation of straw checkerboard techniques significantly increased the beta diversity of the community, leading to species heterogeneity. Species turnover was the main contributor to species beta diversity, and it was caused by high environmental heterogeneity with sand dune stabilization. The contribution of the nestedness component to beta diversity decreased with dune stabilization, indicating that with stabilization, dissimilarity was largely driven by variation in community composition rather than differences in taxonomic richness. This study provides insights into the underlying variation in species composition among sites where mechanical sand fixation engineering has been implemented and important guidelines for combating desertification.

Improved mechanical fixation of an all-polyethylene glenoid reduces postoperative radiolucent lines.

The rationale for advances in implant design is to improve performance in comparison to their predecessors. The purpose of this study was to compare a newer, self-pressurizing peripheral peg glenoid to a traditional polyethylene pegged glenoid through biomechanical evaluation and a retrospective radiographic and clinical review. Three testing conditions (uncemented, partially cemented, and fully cemented) were chosen to assess the 2 component designs in a foam block model. The number of hammer hits to seat the component, amount of time to seat the component, and resistance-to-seat were collected. The implants were then cyclically loaded following ASTM F2028-17 testing standard. Clinically, postoperative radiographs of patients with a self-pressurized glenoid component (n=225 patients) and traditional glenoid component (n=206 patients) were evaluated for radiolucent lines and glenoid seating at various timepoints. Clinical outcomes (American Shoulder and Elbow Surgeons Standardized Shoulder Assessment Form, Simple Shoulder Test, and visual analog scale pain scores) and complications were recorded. The presence of radiolucent lines at the bone-cement interface was evaluated using the Modified Franklin Grade and the Lazarus grade. The self-pressurizing glenoid design required significantly more hammer hits than traditional glenoid designs in all groups tested (P<.029). Moreover, the self-pressurizing design had significantly more resistance-to-seat than traditional components in both the uncemented and partially cemented group (P<.002). No difference in resistance-to-seat was found between designs in the fully cemented group. The uncemented and partially cemented groups did not survive the full 50,000 cycles; however the self-pressurizing design had significantly less motion than the traditional design (P<.001). No differences between component designs were found in the fully cemented group at 50,000 cycles. The self-pressurizing glenoid component had 0.005% radiographic radiolucent lines, and the traditional glenoid component had 45% radiographic radiolucent lines, with 38% of the radiolucencies in the traditional glenoid component group being defined as grade E. There were no progressive radiolucencies, differences in clinical outcomes, or complications at 2 years postoperatively. In the fully cemented condition, the 2 component designs had comparable performance; however, the differences in designs could be better observed in the uncemented group. The self-pressurizing all-polyethylene design studied has superior biomechanical stability. Clinically, the improved stability of the glenoid component correlated with a reduction of radiolucent lines and will likely lead to a reduction in glenoid component loosening.

Cementless Total Knee Arthroplasty Using a Highly Porous Tibial Baseplate in Morbidly Obese Patients: Minimum 5-Year Follow-Up.

Morbidly obese patients undergoing cemented primary total knee arthroplasty (TKA) can pose a challenging problem with implant survivorship due to greater stress at the cement-bone interface. With the advent of additive manufacturing (three-dimensional printing), highly porous implants are now readily available. The purpose of this study was to review the results of primary TKA in the morbidly obese (body mass index [BMI] ≥ 40) patient using a highly porous cementless tibial baseplate. This is a retrospective study of 167 TKAs in patients with morbid obesity undergoing primary cementless TKA with a minimum 5-year follow-up. A total of 6 patients died and 14 were lost to follow-up, leaving 147 TKAs in 136 patients with a mean follow-up of 66 months (range 60-79 months). The average age was 59 years (range 36-84 years) and average BMI was 45 kg/m2 (range 39.5-63.9). Clinical results, patient-reported outcome measures, radiographs, and complications were reviewed. There were 9 failures requiring revision, including 3 for aseptic tibial loosening (2.0%), 2 for deep infection (1.4%), 2 for patellar resurfacing (1.4%), 1 for patella instability (0.7%), and 1 for extensor mechanism rupture (0.7%). Knee Society Score (KSS) improved from 48 to 90 at 2- and 5-year follow-up. KSS function score improved from 49 to 68 and 79 at 2- and 5-year follow-up, respectively. Survivorship with aseptic loosening as the endpoint was 98.0% at 5 years. Cementless TKA using a highly porous tibial baseplate in morbidly obese patients demonstrated excellent clinical results with 98% survivorship at 5 years and appears to offer durable long-term biologic fixation as an alternative to mechanical cement fixation in this challenging group of patients.

High Subsidence Rate After Primary Total Hip Arthroplasty Using a Zweymüller-type Noncemented Implant With a Matte Surface

Introduction:The surface topography is one key factor that affects the initial fixation of prosthesis in total hip arthroplasty (THA). We aimed to evaluate the mid-term results of a Zweymüller-type noncemented femoral implant (Elance stem) that had a matte surface with a target average roughness of 1.0 to 2.5 μm. The prosthesis was subjected to alkali and heat treatments to enhance its bone-bonding property.Methods:In this retrospective study, 30 THAs (27 patients) done using an Elance stem from September 2012 to October 2014 were evaluated clinically and radiographically for a mean follow-up of 6.3 ± 1.7 years after the index THA.Results:Stem revision was indicated for six hips (20%). The survival rate with stem revision for any reason was 86.4% (95% confidence interval, 68.9%-94.8%) at 5 years. Stem subsidence >5 mm was noted in 17 hips (56.7%). The survival rate with stem subsidence >5 mm as the end point was 46.6% (95% confidence interval, 29.9%-64.2%) at 5 years.Conclusion:The Zweymüller-type noncemented stem with a low-roughness matte surface demonstrated a high subsidence rate, although the bone-bonding property was potentially enhanced by the alkali and heat treatments. Surgeons should be aware that an insufficient surface roughness could lead to poor mechanical fixation of the noncemented stem, even with an appropriate stem geometry and surface chemistry.

In Situ Modification of CaF2-SiO2-Al2O3-MgO Flux Applied in the Aluminium-Assisted Transfer of Titanium in the Submerged Arc Welding of Carbon Steel: Process Mineralogy and Thermochemical Analysis

Flux formulations are specified to target chemical and physico-chemical parameters. Chemical parameters set flux element transfer behaviours and weld metal oxygen contents. Physico-chemical parameters such as slag viscosity, surface tension and melting range are targeted to ensure an acceptable weld bead profile and surface appearance. Slag detachability is an important physico-chemical property required to ensure high welding productivity, smooth weld bead surface and no slag entrapment. Here, bead-on-plate welding tests were made with and without metal powder additions, including aluminium powder as a de-oxidiser. Difficult slag detachability was observed in weld runs made with metal powder additions. Mineralogy of the post-weld slags, and thermochemical calculations, show that the flux was modified due to the aluminothermic reduction of MnO and SiO2 from the slag to form alumina. Increased quantities of spinel phase were identified in the post-weld slag samples, at the weld pool–slag interface. The combined effect of increased slag viscosity, from increased spinel in the slag, and lowered weld pool solidus temperature, resulted in the formation of a rough bead surface morphology, which, in turn, caused mechanical fixation of the slag to the weld bead. Flux modification to higher CaF2 content should ensure that higher quantities of spinel phase can be tolerated in the slag.

Stable mechanical fixation in a bionic osteochondral scaffold considering bone growth

Stable mechanical fixation in a bionic osteochondral scaffold considering bone growth

Three-Year Clinical Outcomes and Quality of Life after Retromuscular Resorbable Mesh Repair Using Fibrin Glue.

With 400,000 hernias repaired annually, there is a need for development of efficient and effective repair techniques. Previously, the authors' group compared perioperative outcomes and hospital costs of patients undergoing ventral hernia repair with retromuscular mesh using suture fixation versus fibrin glue. This article reports on 3-year postoperative outcomes, including hernia recurrence, long-term clinical outcomes, and patient-reported quality of life. Patients who underwent ventral hernia repair performed by a single surgeon between 2015 to 2017 were identified. Patients with retromuscular resorbable mesh placed were included and matched by propensity score. Primary outcomes included hernia recurrence, surgical-site infection, surgical-site occurrence, and surgical-site occurrence/surgical-site infection requiring procedural interventions. Secondary outcomes included quality of life as assessed by the Hernia-Related Quality of Life Survey. Sixty-three patients were eligible, and 46 patients were matched (23 suture fixation and 23 fibrin glue), with a median age of 62 years, a median body mass index of 29 kg/m2, and a median defect size of 300 cm2 (interquartile range, 180 to 378 cm2). Median follow-up was 36 months (interquartile range, 31 to 36 months). There was no difference in the incidence of hernia recurrence (13.0 percent for suture fixation and 8.7 percent for fibrin glue; p = 0.636) or other postoperative outcomes between techniques (all p > 0.05). Five patients required reoperation because of a complication (10.9 percent). Overall quality of life improved preoperatively to postoperatively at all time points (all p < 0.05), and no differences in quality-of-life improvement were seen between techniques (p > 0.05). Ventral hernia repair with atraumatic resorbable retromuscular mesh fixation using fibrin glue demonstrates equivalent postoperative clinical and quality-of-life outcomes when compared to mechanical suture fixation. Therapeutic, III.