OBJECTIVES: This study aimed to evaluate the stability of prosthetic screws from three types of craniofacial prostheses retention systems (bar-clip, ball/O-ring, and magnet) when submitted to mechanical cycling. MATERIALS AND METHODS: Twelve models of acrylic resin were used with implants placed 20 mm from each other and separated into three groups: (1) bar-clip (Sistema INP, São Paulo, Brazil), (2) ball/O-ring (Sistema INP), and (3) magnet (Metalmag, São Paulo, Brazil), with four samples in each group. Each sample underwent a mechanical cycling removal and insertion test (f=0.5 Hz) to determine the torque and the detorque values of the retention screws. A servo-hydraulic MTS machine (810-Flextest 40; MTS Systems, Eden Prairie, MN, USA) was used to perform the cycling with 2.5 mm and a displacement of 10 mm/s. The screws of the retention systems received an initial torque of 30 Ncm and the torque values required for loosening the screw values were obtained in three cycles (1,080, 2,160, and 3,240). The screws were retorqued to 30 Ncm before each new cycle. RESULTS: The sample was composed of 24 screws grouped as follows: bar-clip (n=8), ball/O-ring (n=8), and magnet (n=8). There were significant differences between the groups, with greater detorque values observed in the ball/O-ring group when compared to the bar-clip and magnet groups for the first cycle. However, the detorque value was greater in the bar-clip group for the second cycle. CONCLUSION: The results of this study indicate that all prosthetic screws will loosen slightly after an initial tightening torque, also the bar-clip retention system demonstrated greater loosening of the screws when compared with ball/O-ring and magnet retention systems.
Grassland ; Maxillofacial Prosthesis ; Prostheses and Implants* ; Prosthesis Failure ; Prosthesis Retention ; Torque

Skin and soft tissue defect developed after total knee arthroplasty have important influence on prosthesis survival. Thus an adequate treatment have to be performed according to the size and depth of defect. We report a case of dorsalis pedis flap for treatment of skin and soft tissue defect combined with infection after conversion total knee arthroplasty and its good result with a review of the literature.
Arthroplasty ; Knee ; Prosthesis Failure ; Skin

No abstract available.
Cardiopulmonary Bypass ; Heart Valve Prosthesis ; Mitral Valve ; Prosthesis Failure

Aseptic looseningis is one of the most frequent long-term complications after joint replacement, which limits the service lire of prosthesis. A lot of studies have been focused on macrophage, osteoblast, osteoclast and fibroblast in interface membranes around prostheses recently. Aseptic loosening of orthopedic implants used in joint replacement results from bone loss that occurs through the resorptive activity of inflammatory cells activated by the presence of wear particles. Apoptosis has been observed in the periprosthetic site and it has been interpreted as a sign of resolution of inflammation suggesting that apoptosis-related events are indeed associated with periprosthetic osteolysis,targeting the Apoptosis pathway may lead to novel therapeutic approaches for the treatment of aseptic prosthesis loosening. In this thesis,the relationship between wear debris-induced apoptosis and aseptic loosening of prostheses are expounded in detail.
Apoptosis ; Humans ; Joint Prosthesis ; adverse effects ; Osteolysis ; Prosthesis Failure ; etiology

Arthroplasty, Replacement, Hip ; trends ; China ; Hip Prosthesis ; Humans ; Prosthesis Failure

Drug-Eluting Stents ; Humans ; Prosthesis Failure

The clinical failure factors of Orthopedic implants which happened recent years have been summarized. The main failure factors are quality of orthopedic implants itself, iatrogenic and patient-derived. The ways to preventive measures have been suggested.
Orthopedic Procedures ; instrumentation ; Prostheses and Implants ; Prosthesis Failure

Bioprosthesis ; Cardiac Catheterization ; Heart Valve Prosthesis ; Heart Valve Prosthesis Implantation ; Humans ; Prosthesis Failure ; Treatment Outcome

The aim of this study was to compare the accuracy of four different methods for measuring wear using an apparatus that simulates known amounts of three dimensional wear. Wear was measured using the manual methods reported by Charnley, Livermore, Dorr and Wan and the computerized method reported by Devane. Only the method reported by Devane measured the three-dimensional (superior and anterior) wear with a reasonable accuracy, with a mean measurement error of 0.21 mm. With superior wear alone, Charnley's method underestimated the extent of wear by 16.6%, with a mean error of 0.35 mm; Livermore's method estimated wear to within 9.5%, with a mean error of 0.16 mm; Devane's method estimated wear to within 9.5%, with a mean error of 0.15 mm; and Dorr's method underestimated wear by 25.4%, with a mean error of 0.56 mm. Dorr's method was modified as a result of the experimental tests. The clinical application of the new method showed comparable data to that using the Devane method. In conclusion, this new method can be used to estimate the average wear in groups of patients accurately.
Equipment Failure Analysis/instrumentation/methods ; *Hip Prosthesis ; Human ; *Polyethylene ; *Prosthesis Failure ; Stress, Mechanical

Aseptic loosening of the prosthesis is a major form for the failure of artificial joints, which results in the conglomeration of wear particles at the bone-implant interface. This paper briefly reviews the recent development of tribology of artificial joints preserving good lubrication, enhancing the wear resistance of materials for the joints, reducing the generation of sensitive-size particles and depressing the debris-tissue reactions. Suggestion for improvement in the design of artificial joints is presented.
Biocompatible Materials ; chemistry ; Equipment Failure Analysis ; Friction ; Humans ; Joint Prosthesis ; trends ; Lubrication ; Prosthesis Failure