Joint Defects Research Articles

Use of acellular matrices as scaffolds in cartilage regeneration - a systematic review.

Cartilage regeneration remains a significant challenge in the field of regenerative medicine. Acellular matrix-based cartilage tissue regeneration offers an innovative approach to repairing cartilage defects by providing a scaffold for new tissue growth. Its significance lies in its potential to restore joint function, mitigate pain, and improve the quality of life for patients suffering from cartilage-related injuries and conditions. Recent advances in acellular matrix-based cartilage regeneration have focused on enhancing scaffold properties for improved cell adhesion, proliferation, and differentiation. Moreover, several scaffold techniques such as combining ADM and ACM with cartilage tissue, as well as biphasic scaffolding enjoy rising research activity. Incorporating bioactive factors and advanced manufacturing techniques holds promise for producing more biomimetic scaffolds, advancing efficient cartilage repair and regeneration. Obstacles in acellular matrix-based cartilage regeneration include achieving proper integration with surrounding tissue and ensuring long-term durability of the regenerated cartilage. Further, issues such as high costs and limited availability of suitable cells for scaffold seeding must be considered. The heterogeneity and limited regenerative capabilities of cartilage need to be addressed for successful clinical translation. Research should focus on exploring advanced biomaterials and developing new techniques, regarding easily reproductible scaffolds, ideally constructed from clinically validated and readily available commercial products. Findings underline the potential of AM-based approaches, especially rising exploration of tissue-derived ADM and ACM. In future, the primary objective should not only be the regeneration of small cartilage defects, but rather focus on fully regenerating a joint or larger cartilage defect.

DBHF: A double fusion backbone and bidirectional feature hybrid fusion detector for high-precision inspection of avionics solder joint defects

The quality of avionics thermistor wire solder joints has a critical impact on the performance of in-orbit spacecraft. However, it is still hard to simultaneously realize a high-precision inspection of the multi-scale internal and external defects of avionics solder joints. Herein, in combination with active infrared thermography technique, an innovative DBHF detector with a double fusion backbone and a learnable weighted multi-scale bidirectional feature hybrid fusion pyramid network (BdFPN) is demonstrated based on RT-DETR framework. Specifically, the double fusion backbone framework comprises with two lightweight convolutional neural network-based backbones. Compared with conventional single backbone, the double-backbone design forms a multi-level Resnet-like structure, helping to enrich the extracted multi-dimension feature information and retain rich detail information of small-scale defects. The complex learnable weighted multi-scale BdFPN is designed for cross fusion of deep features. One or more additional multi-scale inputs are added to each node involved in feature fusion to aggregate more features from multiple scales and strengthen the interaction between low-level details and high-level semantic information, enabling the detector to make full use of multi-level feature information. Meanwhile, a learnable weight coefficient is set on each node involved in feature fusion and the importance of the input to each node is estimated by training, so that the effective information can be deeply aggregated at different levels. Our DBHF detector achieves a 92.7 % mAP@0.5 on a self-made avionics solder joint dataset with a body size of only 27.2 MB and FPS of 149, outperforming all the typical advanced real-time detectors.

Pediatric Lumbosacral Spondylolisthesis: Overcoming the Disability!

Congenital spondylolisthesis is characterized by dysplasia of the facet joint or congenital defect in the pars. Our study highlights the clinical and radiological profile, various treatment options, and outcomes in patients with pediatric congenital lumbar and lumbosacral spondylolisthesis. A retrospective analysis and follow-up of 22 patients were conducted presented with radiological diagnosis of congenital lumbar/lumbosacral spondylolisthesis (2018-2021). Twenty patients (91%) had L5-S1 listhesis and two patients (9%) had L4-L5 listhesis. Six (27.3%) patients had low-grade listhesis (grades 1-2), 16 (72.7%) had high-grade listhesis (grades 3-5). Seventeen (77.3%) had S1, three (13.6%) had L5, and two (9%) had both L4-L5 radiculopathy. All patients had neurogenic claudication. One had an associated spina bifida occulta. Six (27.3%) patients underwent two-level fixation, and 16 (72.7%) underwent three-level fixation. Minimally Invasive Transforaminal Lumbar Interbody Fusion (MIS TLIF) was done in two patients. Revision of at least one screw was done in three patients. After one year of follow-up, all the patients had 75-100% relief in radicular pain and neurogenic claudication. The Oswestry Disability Index (ODI) score in preop for all patients was 41-60% and postoperatively they showed an improvement in ODI score (0-20). The postoperative low back pain score on the Numeric Rating Scale was 0-1 for all patients. Congenital lumbar spondylolisthesis usually presents with high-grade listhesis. Management of such cases is a surgical challenge but posterior decompression resulted in relief of pain in all patients. However, in situ fixation without reduction is also effective in selective cases where attempts to reduce the listhesis result in a decline in intraoperative neuromonitoring parameters.

Dental rehabilitation of a patient with a decrease in bite height due to pathological abrasion of hard tooth tissues (clinical case)

At the present stage of diagnostics and treatment of dental diseases, morphofunctional disorders of the dento-maxillary system associated with a decrease in the height of occlusion are becoming more common. In the scientific literature, this pathological condition is described under the name "occlusion" that decreases. The reasons that cause it include partial or complete loss of teeth, irrational prosthetics and untimely restoration of dentition defects, doctors' mistakes in the restructuring of the masticatory apparatus, and a generalized form of pathological abrasion of hard tooth tissues. The purpose of the study – demonstration of a clinical case of pathological abrasion of hard tissues of teeth with a decrease in bite height, complicated by defects in the dentition. Patient S., 47 years old, applied for orthopedic help with complaints of anatomical deformity, significant abration of teeth on the upper and lower jaws, increased sensitivity to various types of irritants, partial absence of teeth, impaired masticatory function, periodic clicking in the temporomandibular joint, aesthetic and phonetic defects. Based on the data obtained, we established the following diagnosis: generalized form of pathological abrasion of hard teeth tissues, subcompensated form of reduced bite height, complicated by defects in the dentition of the upper jaw – class I according to the Kenedy classification, lower jaw – class III according to the Kenedy classification. The loss of chewing efficiency according to Agapov was 68%. Patient S. was recommended a two-stage orthopedic treatment, which involves preliminary separation of the bite with the help of individual vinyl mouth guards which have an increasing thickness of 2, 4 and 6 mm, made for the lower jaw.The planned treatment period with each of the muscle relaxant splints will be 2 months. Subsequently, 15, 14, 13, 12, 11, 21, 22, 23, 24 will be restored with one-piece metal crowns with ceramic cladding, and the final defects in the lateral areas will be restored with a clasp prosthesis with a locking system of fixation. The included defect of the lateral part of the lower jaw is planned to be restored with a metal-ceramic bridge-like prosthesis with a support on 47, 45, 44, and the worn-out hard tooth tissues will be completely restored with photopolymer material. In patients with a reduction in bite height of more than 2 mm, it is advisable to carry out treatment in two stages. At the first stage, we normalize the occlusal height and rebuild the function of the masticatory muscles. At the second stage, we provide rational prosthetics. Orthopedic rehabilitation with myorelaxing splints of increasing thickness makes it possible to correctly rebuild myostatic reflexes and prevent functional disorders in the TMJ. Any case of complex treatment of patients with a decrease in bite height due to pathological abrasion of the hard tooth tissues deserves the attention of both scientists and dentists in practical health care.

Use of threaded cylindrical pin tools to reduce macroscopic defects in dissimilar welded joints of AA7075-T6 and AZ31B alloys by the FSW process

The continued increase in greenhouse gas emissions has had dire consequences for the global climate. In order to reduce such emissions, several efforts have been made by researchers in the transport sector, such as the development of electric motorization, the development of hybrid engines, the use of biofuels and the use of light alloys. The use of light alloys such as aluminum and magnesium in vehicles can reduce the emission per kilogram of vehicles drastically, however, it is still necessary to develop effective and more agile methods of the dissimilar joints of these materials. Some authors have studied the friction stir welding of AZ31B magnesium alloys and AA7075-T6 aluminum alloys in order to determine better process parameters to enable this bond, however, few articles have been published in order to evaluate the influence of tool geometry on such properties. In this sense, this article aims to evaluate the influence of friction welding tool pin geometry as smooth cylindrical pin, threaded cylindrical pin, conical and hexagonal pin configurations in the formation of the mixed zone of welds manufactured by the FSW process. For this purpose, AZ31B and AA7075-T6 alloys were welded by FSW with welding speed of 75 mm/min, tool rotation speed of 565 rpm, offset of 0.5mm and inclination of the tool geometry in relation to the plates to be welded of 3º, the joints were evaluated for their macro and microstructures and Vickers hardness with a load of 100 gf. It was possible to observe that the joints welded with the threaded cylindrical pin tool presented stir zones free of macroscopic defects, similar hardness values for the four tools studied and the presence of a thin layer of intermetallics between TMAZ and SZ on the AZ31B side.

Anomalous attenuation phenomenon of terahertz wave through the micron air gap defects in XLPE insulation material

During the fabrication process of the factory joint in submarine cables, manual cutting and polishing are required, which can easily result in scratches, pits, and other defects. Meanwhile, due to the limitations of insulation recovery and injection molding technology, air gap defects are prone to occur inside the joints, posing significant safety hazards. In order to preemptively detect such defects before the cable is put into operation, this study mimics the insulation recovery process of the cable joint to create micron air gaps inside the insulation and uses terahertz imaging technology to visualize them. The results indicate that 153 μm and 76 μm arc-shaped air gaps can be clearly recorded by terahertz imaging systems. Meanwhile, terahertz time-domain signals clearly show that the electromagnetic waves experience a significant attenuation of up to 45 % after passing through the arc-shaped air gap, and their energy exhibits an uneven distribution. To explain the propagation phenomena of terahertz waves in micron air gaps, this study proposes a propagation model based on absorption effects, reflection effects, partial interference effects, and off-axis Gaussian scattering effects. This paper proved the potential of terahertz waves in detecting air gap defects in cables joint. The associated theoretical models can be utilized to develop targeted imaging algorithms.

Effect of Defects in Lap Joints Between AZ31B and Ti-6Al-4V Alloys Processed Using Gas Tungsten Arc Welding

Effect of Defects in Lap Joints Between AZ31B and Ti-6Al-4V Alloys Processed Using Gas Tungsten Arc Welding

Treatment of Shoulder Cartilage Defects in Athletes.

Articular cartilage defects in the glenohumeral joint may be found in laborers, the elderly, and young athletes, among others. Various factors can contribute to cartilage damage, including prior surgery, trauma, avascular necrosis, inflammatory arthritis, joint instability, and osteoarthritis. There is a wide variety of treatment options, from conservative treatment, injections, and surgical options, including arthroscopic debridement, microfracture, osteochondral autograft transfer, osteochondral graft transplantation, autologous chondrocyte implantation, and the newly emerging techniques such as biologic augmentation. There is a challenge to determine the optimal treatment options, especially for young athletes, due to limited outcomes in the literature. However, there are many options which are viable to address osteochondral defects of the glenohumeral joint.

Comparison of Novel 3D-printed Stepped Porous Metal Cones and Metaphyseal Sleeves for Reconstruction of Severe Knee Bone Defects: Short-term Clinical Outcomes.

Both porous metal cones and metaphyseal sleeves are excellent implants for reconstructing severe bone defects in the knee joint, but they both exhibit design limitations. The porous metal cone, especially, has significant room for improvement in its shape design. The existing porous metal cones often feature a conical external surface with a relatively small taper, potentially compromising both rotational and axial stability. To improve both axial and rotational stability in porous metal cones, we developed a 3D-printed stepped porous metal cone. This study aimed to assess the short-term clinical outcome of the 3D-printed stepped porous metal cone and to compare it with the clinical outcome of patients who underwent revision total knee arthroplasty (rTKA) with the metaphyseal sleeves during the same period. Patients who underwent total knee arthroplasty revision with metaphyseal bone defect reconstruction from 2019 to 2021 were retrospectively analyzed. A total of 61 patients were enrolled in the study, including 15 patients using 3D-printed stepped porous metal cones and 46 patients using metaphyseal metal sleeves. Thirty patients using metaphyseal sleeves were screened by propensity score matching method and compared with those using stepped cones. Analysis included the American Knee Society Score, the Hospital for Special Surgery knee score, the Western Ontario and McMaster Universities Arthritis index, the Short Form 12 (SF-12) health survey, and radiographic assessment with a mean follow-up of 28.5 ± 8.3 months. To conduct comparative analyses, unpaired Student's t-tests were employed for continuous variables, while categorical variables were analyzed using the appropriate Fisher exact or chi-squared test. In this study, the survival rates of both the stepped cone and metaphyseal sleeve were 100%. There was no statistically significant difference in postoperative knee function scores between the two groups (p > 0.05). However, patients in the cone group had significantly higher mental component summary scores on the SF-12 scale (p < 0.05) and higher increases in mean postoperative physical component summary scores than patients in the sleeve group (p < 0.05). In addition, patients in the cone group experienced fewer intraoperative and postoperative complications compared to the sleeve group. The 3D-printed stepped porous metal cone can effectively reconstruct bone defects in complex rTKA and provide satisfactory early clinical and radiographic results. The 3D-printed stepped cone provides a more stable structure similar to the sleeve while maintaining the original benefits of the cone making it a promising choice for rTKA.

Formation mechanism and elimination method of joint defects in lattice structures printed by metal droplet deposition manufacturing

Benefiting from the dense inner microstructure and smooth bead-like surface morphology, metal droplet deposition manufacturing (MDDM) is advantageous in manufacturing small metallic lattice structures, which have great potential in advanced aerospace, energy, and robotics applications. However, the improper top-layer droplet distance leads to joint defects in the printed lattices and deteriorates the forming accuracy. Moreover, if the substrate temperature and inclined angle increase, joint defects may occur even if the top-layer droplets are at an ideal distance due to droplet oscillation. This work proposes a novel method to eliminate joint defects by re-placing the joint region droplets to an ideal center distance. To this end, the dynamics of top-layer droplets (impact, spread, recoil, and oscillation) were investigated by combining morphology analysis and high-speed photography (Ts = 673 K, θ = 45°). A theoretical model was established to obtain the parameter range of defect-free joints through a series of bifurcate lattice printing experiments. Then, the morphology and generation mechanism of cumulative joint defects in the lattices at higher temperatures and angles (Ts = 773 K, θ = 60°) were analyzed. A parameter window of joint morphology with different values of inclined angle, substrate temperature, and top-layer droplet distance was established for predicting potential defects in the printing trace. Next, a novel method was proposed to remove redundant droplets and re-place top-layer droplet coordinates into the ideal center distance. Furthermore, the printing strategy was expanded to multi-truss lattices using three-dimensional transformation matrixes. Finally, multiple cells bifurcate, triangular, and pyramid lattices were successfully printed with perfect joints. The height deviation of joint regions is <5 % of the droplet diameter, verifying the feasibility of the proposed strategy. This work represents a further step towards MDDM printing of high-quality truss lattice structures and other complex 3D architectures.

ISOLATED ANKLE FUSION FOR FAILED TOTAL ANKLE ARTHROPLASTY USING A SPINE CAGE AND ANTERIOR PLATING CONSTRUCT

BackgroundTotal ankle replacements (TARs) are becoming increasingly more common in the treatment of end stage ankle arthritis. As a consequence, more patients are presenting with the complex situation of the failing TAR. The aim of this study was to present our case series of isolated ankle fusions post failed TAR using a spinal cage construct and anterior plating technique.MethodsA retrospective review of prospectively collected data was performed for 6 patients that had isolated ankle fusions performed for failed TAR. These were performed by a single surgeon (IW) between March 2012 and October 2014. The procedure was performed using a Spinal Cage construct and grafting in the joint defect and anterior plating. Our primary outcome measure was clinical and radiographic union at 1 year. Union was defined as clinical union and no evidence of radiographic hardware loosening or persistent joint lucent line at 1 year.ResultsThe mean follow-up was 37.3 months (SD 13.2). Union was achieved in 5 of the 6 patients (83%). One patient had a non-union that required revision fusion incorporating the talonavicular joint that successfully went on to unite across both joints. Another patient had radiographic features of non-union but was clinically united and asymptomatic and one required revision surgery for a bulky symptomatic lateral malleolus with fused ankle joint.ConclusionThe failing TAR presents a complex clinical situation. After removal of the implant there is often a large defect which if compressed leads to a leg length discrepancy and if filled with augment can increase the risk of non-union. Multiple methods have been described for revision, with many advocating fusion of both the ankle joint and subtalar joint. We present our case series using a spinal cage and anterior plating that allows preservation of the subtalar joint and a high rate of union.

Osteochondral Allograft Transplantation: A Technical Note

Background: Chondral injuries in the knee are commonly discovered during knee arthroscopy procedures. Due to the poor restoration potential and avascular nature of cartilage, large defects are commonly treated with such surgical procedures. Treatment utilizing an osteochondral allograft (OCA) transplant for symptomatic focal cartilage defects in the patellofemoral joint has demonstrated strong, lasting clinical and radiographic outcomes. Indications: Active and otherwise healthy patients are indicated for surgery when presenting with significant joint-line pain and a large focal chondral defect verified on advanced imaging after an extensive course of nonoperative management. Technique Description: Beginning with diagnostic arthroscopy to confirm the large defect of the medial femoral condyle, we proceeded with OCA transplantation. A small medial peripatellar arthrotomy is performed. The fat pad is removed for visualization and retractors are placed both medially and laterally to appropriately visualize the defect. The defect is then sized according to the appropriate sizing guide. The guide is then placed perpendicular to the defect, and a central guide pin is drilled. A scoring reamer is used to carefully cut the size of the defect followed by a central reamer to prepare the defect. Any debris is removed, and the incision is thoroughly irrigated. The defect is then carefully measured in all four quadrants to match the donor. Any underlying bone is impacted for a stable base. A drill is then used for appropriate marrow venting underneath the defect. The corresponding donor site is selected and reamed with continuous irrigation to prevent thermal necrosis. The plug is removed and carefully measured to match the recipient site. The plug is thoroughly irrigated with pulse lavage to remove marrow elements. The graft is carefully inserted with gentle manual pressure until it is seated perfectly flush with the surrounding cartilage. Results: Clinical research has demonstrated good-to-excellent long-term survivorship of OCA transplantation. Long-term return to sport rates for recreational and competitive athletes are upward of 75%. Discussion/Conclusion: As surgical techniques continue to develop, surgeons should consider utilizing OCA transplants to treat large chondral defects in the patellofemoral joint. Patient Consent Disclosure Statement: The author(s) attests that consent has been obtained from any patient(s) appearing in this publication. If the individual may be identifiable, the author(s) has included a statement of release or other written form of approval from the patient(s) with this submission for publication.

The preparation and wettability of the Sn-9Zn-2.5Bi-1.5In solder paste for SMT process and high shear ball performance

Purpose This study aims to focus on the surface mount technology (SMT) mass production process of Sn-9Zn-2.5Bi-1.5In solder. It explores it with some components that will provide theoretical support for the industrial SMT application of Sn-Zn solder. Design/methodology/approach This study evaluates the properties of solder pastes and selects a more appropriate reflow parameter by comparing the microstructure of solder joints with different reflow soldering profile parameters. The aim is to provide an economical and reliable process for SMT production in the industry. Findings Solder paste wettability and solder ball testing in a nitrogen environment with an oxygen content of 3,000 ppm meet the requirements of industrial production. The printing performance of the solder paste is good and can achieve a printing rate of 100–160 mm/s. When soldering with a traditional stepped reflow soldering profile, air bubbles are generated on the surface of the solder joint, and there are many voids and defects in the solder joint. A linear reflow soldering profile reduces the residence time below the melting point of the solder paste (approximately 110 s). This reduces the time the zinc is oxidized, reducing solder joint defects. The joint strength of tin-zinc joints soldered with the optimized reflow parameters is close to that of Sn-58Bi and SAC305, with high joint strength. Originality/value This study attempts to industrialize the application of Sn-Zn solder and solves the problem that Sn-Zn solder paste is prone to be oxidized in the application and obtains the SMT process parameters suitable for Sn-9Zn-2.5Bi-1.5In solder.

Friction stir welded joints in aluminum highway bridge decks: a quality control framework

Friction stir welding (FSW) has shown considerable promise for highway aluminum bridge deck fabrication but lacks specific quality control guidelines for fit-up defects. This study conducts a performance-based (PB) quality control assessment of butt-lap FSW joints for highway bridge decks. Five FSW conditions were simulated, including a standard control welding condition, fit-up defects (gaps and tool offset), and a welding tool’s rotational direction inversion from the standard condition. A rigorous prequalification process established acceptable tolerance levels for fit-up defects: a 3 mm positive offset, a 1.5 mm negative offset, and a 1.5 mm gap. Subsequently, specimens from real aluminium deck extrusions, incorporating the various welding conditions were subjected to fatigue testing. Results showed that the fatigue strength and failure mode were primarily influenced by the weld root microstructure. The FSW tool’s rotational direction significantly influenced fatigue strength due to its impact on the nucleation of the hooking defect in the weld root area, while the impact of fit-up defects on fatigue strength was comparatively lesser. Furthermore, finite element analysis examined the impact of the geometrical features of the root microstructure and the direction of the initial crack propagation on the stress intensity factor range. These findings have practical implications for setting tolerance levels for fit-up defects in aluminum butt-lap FSW joints and optimizing of the quality and fatigue strength of butt-lap FSW joints.

Non-destructive detection and analysis of weld defects in dissimilar pulsed GMAW and FSW joints of aluminium castings and plates through 3D X-ray computed tomography

AbstractThis work focuses on porosity formation during the welding of dissimilar aluminium alloys (cast and sheet) by pulsed gas metal arc welding (GMAW) with different travel speeds (12–14 mm/s) and by friction stir welding (FSW). The case study concerns the assembling of a battery-pack enclosure prototype. The welded specimens were scanned by 3D X-ray computed tomography. The cast base material (BM) shows a porosity percentage of 1.45%, and it is characterized by pores with a strong hyperbolic relationship between equivalent diameter and sphericity. Considering the GMAW beads, porosity rises with the travel speed (from 1.80 to 5.12%), due to the reduction of the opening window in which pores can escape. Pores with volume higher than 0.10 mm3 rise with the travel speed, representing from 9.75 to 32.98% of the total porosity. These pores are responsible for the weaker hyperbolic connection for sphericity found for the GMAW beads. On the other hand, FSW mixes and homogenizes the pores in the cast BM. The novelty of the paper lays in proving the strong potentialities of FSW for weld porosity reduction. A re-designing of the battery-pack enclosures is necessary to limit arc welding in marginal areas, which are not crucial for sealing but necessary to create a stable platform to be subsequently sealed with FSW.

Preliminary study on terahertz non-destructive testing for defect detection in hot melt joints of polyethylene pipes

With the rapid development of the economy and society, non-metallic pipelines are more and more widely used in oil and gas fields, water supply projects, urban gas systems, and so on. Among the conventional nondestructive testing (NDT) methods, only ultrasonic, radiographic, and penetration testing tools are applicable to non-metallic pipe examination from a theoretical perspective, while their actual efficiency is quite low. In this work, terahertz (THz) non-destructive detection of typical welding defects in polyethylene-pipe hot melt joints is carried out. The characteristic THz wave signal is obtained, and the relationship between the THz wave and the defect type is established. Finally, a THz signal processing model for defect detection in polyethylene-pipe hot melt joints is established. Thus, this research lays a foundation for the application of the THz non-destructive testing technology to polyethylene pipeline engineering.

In-situ observation of molten brazing filler metal permeating gap

Generally, brazing is completed when the brazing filler metal permeates the gap by uniform wetting. It is believed that the joining process is completed with the formation of joint defects ‘voids’ in the process of uniform wetting. However, previous studies have shown that what occurs when brazing is performed is non-uniform wetting. It is suggested that this non-uniform wetting is the cause of void generation. Wetting and spreading of brazing filler metal is tested on a metal plate, as described in JIS Z 3191. This is used to investigate the wetting of the brazing filler metal. However, this method does not cover the wetting of the molten brazing filler metal as it moves into the gap. Therefore, it is suggested that the JIS Z 3191 experiment is insufficient to evaluate the wetting of the molten brazing filler metal that penetrates into the gap. In this experiment, we created new specimen. It is called us ‘V-groove specimen’. Specimens were created with two base metals. They are pure copper and lead-free brass in which bismuth was used as an alternative element. In order to do in situ experiments, it was not possible to observe the inside of a conventional electric furnace. Therefore, we produced a furnace with a window for in-situ observation and experimented with it. As a result of experiments with V-groove specimens, it was found that there are two types of wetting of brazing filler metal. They are called ‘primary wetting’ and ‘secondary wetting’. The shape of the specimen was measured and evaluated for two types of wetting. The results showed that the primary wetting was measurable in shape and spread evenly. However, the shape of the secondary wetting could not be measured, and it was found to be non-uniformly spread.

The value of magnetic resonance diffusion weighted imaging sequence and T2 mapping imaging technology in evaluating knee joint defects

The value of magnetic resonance diffusion weighted imaging sequence and T2 mapping imaging technology in evaluating knee joint defects

Depriving friction stir weld defects in dissimilar aluminum lap joints

The contemporary automotive industry increasingly incorporates composite materials and innovative joining techniques to meet customer demands for lightweight, high-strength alloys. This research explores the feasibility of using friction stir welding (FSW) methods to fabricate dissimilar aluminum nanocomposite lap joints, integrating Al2O3 nanoparticles into the weld nugget. Lap joints were prepared with varying tool rotation speeds (1000–1600 rpm) and the mechanical and metallurgical behaviors of AA6061–AA7075-T6/Al2O3 lap joints were examined. The inclusion of filler material in the weld joint resulted in an 18% increase in shear strength compared to joints without filler. Dynamic crystallization impeded grain boundaries and reduced grain size in the weld stir zone (SZ), with the most enhanced mechanical characteristics observed at a tool rotation speed of 1400 rpm. The shear strength at 1400 rpm was 5780 N, representing a 17% increase compared to joints prepared at 1000 rpm. Field emission scanning electron microscopic examination revealed evenly dispersed Al2O3 nanoparticles within the weld zone, supporting the lap shear test results. Notably, joints created at lower (1000 rpm) and higher tool rotational speeds (1600 rpm) exhibited brittle fracture behavior. The addition of Al2O3 significantly improved lap joint tensile strength due to its uniform dispersion in the SZ. Increasing the FSW tool rotational speed from 1000 to 1400 rpm facilitated nanoparticle dispersion, further enhancing lap joint strength.

A comparative analysis of 3D bioprinted gelatin-hyaluronic acid-alginate scaffold and microfracture for the management of osteochondral defects in the rabbit knee joint.

This study aims to compare the radiological, biomechanical, and histopathological results of microfracture treatment and osteochondral damage repair treatment with a new scaffold product produced by the three-dimensional (3D) bioprinting method containing gelatin-hyaluronic acid-alginate in rabbits with osteochondral damage. A new 3D bioprinted scaffold consisting of gelatin, hyaluronic acid, and alginate designed by us was implanted into the osteochondral defect created in the femoral trochlea of 10 rabbits. By randomization, it was determined which side of 10 rabbits would be repaired with a 3D bioprinted scaffold, and microfracture treatment was applied to the other knees of the rabbits. After six months of follow-up, the rabbits were sacrificed. The results of both treatment groups were compared radiologically, biomechanically, and histopathologically. None of the rabbits experienced any complications. The magnetic resonance imaging evaluation showed that all osteochondral defect areas were integrated with healthy cartilage in both groups. There was no significant difference between the groups in the biomechanical load test (p=0.579). No statistically significant difference was detected in the histological examination using the modified Wakitani scores (p=0.731). Our study results showed that 3D bioprinted scaffolds exhibited comparable radiological, biomechanical, and histological properties to the conventional microfracture technique for osteochondral defect treatment.