ABSTRACT
Knee osteoarthritis is treated based on total knee arthroplasty (TKA) interventions. The most frequent failure cause identified in surgical practice is due to wear and oxidation processes of the prothesis' tibial insert. This component is usually manufactured from ultra-high molecular weight polyethylene (UHMWPE). To estimate the clinical complications related to a specific prosthesis design, we investigated four UHMWPE tibial inserts retrieved from patients from Clinical Hospital Colentina, Bucharest, Romania. For the initial analysis of the polyethylene degradation modes, macrophotography was chosen. A light stereomicroscope was used to estimate the structural performance and the implant surface degradation. Scanning electron microscopy confirmed the optical results and fulfilled the computation of the Hood index. The oxidation process in UHMWPE was analyzed based on Fourier-transform infrared spectroscopy (FTIR). The crystallinity degree and the oxidation index were computed in good agreement with the existing standards. Mechanical characterization was conducted based on the small punch test. The elastic modulus, initial peak load, ultimate load, and ultimate displacement were estimated. Based on the aforementioned experimental tests, a variation between 9 and 32 was found in the case of the Hood score. The oxidation index has a value of 1.33 for the reference sample and a maximum of 9.78 for a retrieved sample.
ABSTRACT
Magnesium (Mg)-based alloys have become an important category of materials that is attracting more and more attention due to their high potential use as orthopedic temporary implants. These alloys are a viable alternative to nondegradable metals implants in orthopedics. In this paper, a detailed overview covering alloy development and manufacturing techniques is described. Further, important attributes for Mg-based alloys involved in orthopedic implants fabrication, physiological and toxicological effects of each alloying element, mechanical properties, osteogenesis, and angiogenesis of Mg are presented. A section detailing the main biocompatible Mg-based alloys, with examples of mechanical properties, degradation behavior, and cytotoxicity tests related to in vitro experiments, is also provided. Special attention is given to animal testing, and the clinical translation is also reviewed, focusing on the main clinical cases that were conducted under human use approval.
