Biomimetic Artificial Joints Based on Multi-Material Pneumatic Actuators Developed for Soft Robotic Finger Application

To precisely achieve a series of daily finger bending motions, a soft robotic finger corresponding to the anatomical range of each joint was designed in this study with multi-material pneumatic actuators. The actuator as a biomimetic artificial joint was developed on the basis of two composite materials of different shear modules, and the pneumatic bellows as expansion parts was restricted by frame that made from polydimethylsiloxane (PDMS). A simplified mathematical model was used for the bending mechanism description and provides guidance for the multi-material pneumatic actuator fabrication (e.g., stiffness and thickness) and structural design (e.g., cross length and chamber radius), as well as the control parameter optimization (e.g., the air pressure supply). An actuation pressure of over 70 kPa is required by the developed soft robotic finger to provide a full motion range (MCP = 36°, PIP = 114°, and DIP = 75°) for finger action mimicking. In conclusion, a multi-material pneumatic actuator was designed and developed for soft robotic finger application and theoretically and experimentally demonstrated its feasibility in finger action mimicking. This study explored the mechanical properties of the actuator and could provide evidence-based technical parameters for pneumatic robotic finger design and precise control of its dynamic air pressure dosages in mimicking actions. Thereby, the conclusion was supported by the results theoretically and experimentally, which also aligns with our aim to design and develop a multi-material pneumatic actuator as a biomimetic artificial joint for soft robotic finger application.

Finite Element Analysis of the Lower Extrtemity - Hinge Knee Behavior Under Dynamic Load

A key goal of joint endoprosthesis is to become a full-featured functional and anatomical replacement. The joint damage may occur for several reasons - primarily a disease of different nature and magnitude, resulting in gradual and irreversible changes and in an extreme solution in the implantation of artificial joints. However, there should be also mentioned accidents leading to joint destruction, which are often "trigger mechanism" of the disease. This work therefore presents a dynamic computational finite element analysis of a hinge-type knee replacement, which aim to streamline and accelerate the development of knee endoprosthesis. It tackles a question of the overall strength of the implant and detects sites of elevated concentrations of stresses that may be potential sources of implant damages. It also studies the behavior of the endoprosthesis under dynamic loads with emphasis on the study of the shape and size of the contact surfaces, which are closely related to the size of the contact pressure and material wear. Aside the hinged knee replacement, the computational model consisted of femur, fibula, tibia, patella and 25 most important muscles of the lower limb. Due to realistic definition of the boundary conditions, this model is suitable for investigation of invivo knee joint replacement behavior.

Femoral Osteotomies for Osteonecrosis of the Femoral Head

Femoral osteotomy is performed for osteonecrosis of the femoral head to prevent the progression of collapse and promote the repair process by transposing the necrotic lesion to the nonweight-bearing portion. The purpose of this review article was to summarize the current knowledge on two types of femoral osteotomy: transtrochanteric anterior or posterior rotational osteotomy and transtrochanteric curved varus osteotomy, both of which are currently performed for osteonecrosis, mainly in Japan and Korea. Osteotomy can be expected to cure osteonecrosis, and no matter how much the durability of artificial joints improves, there will always be young patients for whom the procedure is indicated. We should continue to verify the results of this surgery and refine the techniques involved.

Study on Wear Debris Characterization of Polycarbonate Urethane (PCU) as a Bearing of Artificial Hip Joint

As with all artificial joints, wear debris is of particular concern due to its effect on both implant life and the in vivo biological reactions that can occur. The purpose of the research is to study debris characterization of PCU. Wear particle is produced from testing the PCU material using a pin on disc wear tester within 50000 cycles. This study showed that the PCU wear debris gotten from the simulator had various different shapes, including laminar and spherical types. The morphology of worn surface and wear debris analysis showed that wear mechanism of PCU were fatigue wear. Thus we conclude that PCU is expected to be a lifetime implantation of artificial joint.

Microcalorimetry—Versatile Method of Describing Bacterial Growth

(1) Background: Due to the aging population in industrialized countries and due to the increase in the number of traffic or sports accidents, the number of artificial joints and implants for osteosynthesis will increase in the coming years. Therefore, the risk of postoperative infections will be higher as well. (2) Methods: For this study, we combined classical bacterial identification with the description of bacterial growth curves using microcalorimetry. (3) Results: We evaluated the growth of S. aureus and S. epedermidis, but we believe that this can be applied to any anaerobic or aerobic bacterial colony. We discovered that the time interval after which we can identify a growth curve does not exceed 15–20 h. (4) Conclusions: The diagnosis made by combining the methods of sonication and microcalorimetry manages to provide a great deal of information about the bacteria we studied. Microcalorimetry has real potential as a method for obtaining quick diagnosis in various cases of infection, but many more experiments need to be done to ensure the correct use of this technique. A detailed investigation (including kinetic analysis) of the reproducible thermal signal of bacterial growth can lead to the development of alternative means of rapid bacterial identification.

Rheological Properties and Its Effect on the Lubrication Mechanism of PVP K30 and PVP 40-50 G as Artificial Synovial Fluids

The effect of polyvinylpyrrolidone (PVP) on the rheological properties of joint prostheses is still unclear, despite its good lubricity and biocompatibility. In the present work, PVP K30 and PVP 40-50 G solutions at different concentrations were analyzed for rheological and lubrication properties. The rheological properties of the samples were measured at a shear rate range of 0–1800 s−1 (advanced air bearing rheometer Bohlin Gemini 2 and Plate MCR 72/92 rheometer for PVP30 and PVP 40-50 G, respectively). It was found that both the viscosity and shear stress of the samples reduced with a shear rate increase. PVP 40-50 G/sterile water showed higher viscosity as compared to the PVP K30/sterile water sample at a lower shear rate. However, at a higher shear rate, the PVP K30 sample produced better results. Further numerical study results showed the pressure and molecular viscosity distributions. The inclusion of PVP improved the load caring capacity and hence, it is a promising lubrication additive for artificial joints.

Morphological residual convolutional neural network (M-RCNN) for intelligent recognition of wear particles from artificial joints

Finding the correct category of wear particles is important to understand the tribological behavior. However, manual identification is tedious and time-consuming. We here propose an automatic morphological residual convolutional neural network (M-RCNN), exploiting the residual knowledge and morphological priors between various particle types. We also employ data augmentation to prevent performance deterioration caused by the extremely imbalanced problem of class distribution. Experimental results indicate that our morphological priors are distinguishable and beneficial to largely boosting overall performance. M-RCNN demonstrates a much higher accuracy (0.940) than the deep residual network (0.845) and support vector machine (0.821). This work provides an effective solution for automatically identifying wear particles and can be a powerful tool to further analyze the failure mechanisms of artificial joints.

Lubrication Effect of Polyvinyl Alcohol/Polyethylene Glycol Gel for Artificial Joints

One of the most common problems encountered by patients using artificial joints is the high wear rate. In this study, a polyvinyl alcohol/polyethylene glycol (PVA/PEG) gel was prepared through the cross-linking reaction between polyvinyl alcohol (PVA) and polyethylene glycol (PEG) solutions. This gel can lubricate artificial joints, thereby lowering their coefficient of friction (COF) and increasing their service life. Various techniques, such as Fourier transform infrared spectroscopy, X-ray diffraction, Raman spectra, X-ray photon spectroscopy, and thermogravimetric analyses, were used to analyze the structure of this synthetic gel. The tribological results indicated that the synthetic gel’s lubrication effect was the most optimum when it contained PVA (10 wt%) and PEG (15 wt%). An average COF of 0.05 was obtained under a load of 10 N and at a speed of 1.0 cm/s. In addition, the wear rate was reduced in comparison to distilled water. Furthermore, the biological tests proved that the PVA/PEG gel was highly biocompatible. Thus, this study introduces a novel technique to prepare PVA/PEG gels that improve the tribological performance of artificial joints.