For the improvement of surface roughness, titanium joint arthroplasty (TJA) components are grit-blasted with Al2O3 (corundum) particles during manufacturing. There is an acute concern, particularly with uncemented implants, about polymeric, metallic, and corundum debris generation and accumulation in TJA, and its association with osteolysis and implant loosening. The surface morphology, chemistry, phase analysis, and surface chemistry of retrieved and new Al2O3 grit-blasted titanium alloy were determined with scanning electron microscopy (SEM), X-ray energy-dispersive spectroscopy (EDS), transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS) and confocal laser fluorescence microscopy, respectively. Peri-prosthetic soft tissue was studied with histopathology. Blasted retrieved and new stems were exposed to human mesenchymal stromal stem cells (BMSCs) for 7 days to test biocompatibility and cytotoxicity. We found metallic particles in the peri-prosthetic soft tissue. Ti6Al7Nb with the residual Al2O3 particles exhibited a low cytotoxic effect while polished titanium and ceramic disks exhibited no cytotoxic effect. None of the tested materials caused cell death or even a zone of inhibition. Our results indicate a possible biological effect of the blasting debris; however, we found no significant toxicity with these materials. Further studies on the optimal size and properties of the blasting particles are indicated for minimizing their adverse biological effects.
26 February 2020 in International Journal of Rehabilitation Research
World demography is changing as the population ages and there are more people with disabilities having problems to stay independently at home. Innovative technologies could help extend the independence of older people living at home. As part of a collaborative project, we investigated ownership and use of information and communication technologies (ICT) among older people with lower limb loss (LLL) using questionnaires and retrospective analysis. Our aim was to analyse factors associated with ICT use among people with LLL. We identified age as the main factor that limits ownership and use of ICT among older people with LLL in Slovenia. Cause of amputation also appears to be relevant, whereby those who had amputation because of peripheral vascular disease are more likely to use a personal or tablet computer, social networks, messaging apps, email and internet than those who had amputation because of diabetes. In addition, those living in the suburbs are more likely to use a health monitoring device than those living in the countryside.
In this paper, we present the mechanisms of premature fracture of modular neck stems in two case studies: (I) when the neck and stem are both made of the same Ti6Al4V alloy, and (II) when the neck and stem are made from two different alloys, CoCrMo and Ti6Al4V alloy. Our study integrates two orthopedic patients who have undergone primary uncemented THA for usual indications in two orthopedic centers (Community Health Centre and University Medical Centre). Both centers are part of the national public health care system. Both surgeries were performed by two skilled orthopedic surgeons with more than 10 years of experience in THA. The survivorship of the modular neck of cast CoCrMo alloy was 24 months. The survivorship of the modular neck from Ti6Al4V alloy was 84 months. Multivariate analyses were performed to assess the differences in the fretting, corrosion, and fatigue of the two prematurely failed modular neck stems: stereo light microscopy (SLM), scanning electron microscopy (SEM), X-ray energy-dispersive spectroscopy (EDS), and electron backscatter diffraction (EBSD). Patient demographic information, including sex, age, body mass index, survivorship of implants, and reason for the revision, was collected from medical records. We found that fretting and fatigue occurred on both neck-stem retrievals due to additional galvanic corrosion, but the CoCrMo/Ti6Al4V alloy system suffered more corrosion due to additional galvanic corrosion and fractured earlier than the Ti6Al4V/Ti6Al4V metal alloy system. Both metallic alloy systems used in this application are known to be highly corrosion-resistant, but the bio-tribo-corrosion processes need to be understood in detail and characterized so that appropriate improvements in design and materials can be made.
Total hip arthroplasty (THA) is a widely performed and successful surgical treatment for degenerative joint disease. With increasing use in younger and more active patients, the demand for durable, biocompatible, and low-wear implant materials has grown. Oxidized zirconium (Oxinium, Zr2.5Nb) was introduced as a promising femoral head material, combining the strength of metal with the low-friction properties of ceramic. Despite encouraging early results, clinical reports have documented complications including head wear, especially after dislocation, and metallosis. We present the case of a 64-year-old male who underwent primary THA in 2009 and required revision in 2021 due to severe metallosis. Notably, no dislocation was observed that could explain the damage to the Oxinium head. Surface and subsurface analyses using X-ray photoelectron spectroscopy (XPS) and micro-indentation hardness testing revealed wear and deformation inconsistent with Oxinium’s anticipated durability. These findings highlight the importance of the femoral head–polyethylene liner interface in implant longevity. Although Oxinium–XLPE articulations remain promising, risks such as damage to the femoral head, liner dislocation, impingement, and metallosis must be carefully considered. Surgical technique, liner placement, and locking mechanisms play critical roles in preventing failure. Further biomechanical and clinical studies are needed to optimize implant design and improve long-term outcomes.
We investigated micro-threaded stem taper surface and its impact on premature failures, aseptic loosening, and infection in cementless hip endoprostheses. Our study focused on the fretting, and crevice corrosion of micro-threaded tapers, as well as the characterization of the microstructure and surface properties of two new and three retrieved Zweymüller stem tapers. The retrieved samples were selected and examined based on the head–stem taper interface being the sole source of modularity with a metallic component, specifically between the Ti alloy taper stem and the ceramic head. To determine the surface chemistry and microstructures of both new and retrieved hip endoprostheses stem taper titanium alloy, scanning -electron microscopy (SEM) was employed for morphological and microstructural analyses. Energy dispersive spectroscopy (EDS) was utilized for characterizing chemical element distribution, and electron backscattered diffraction (EBSD) was used for phase analysis. The roughness of the micro-threated stem tapers from different manufacturers was investigated using an optical profilometer, with standard roughness parameters Ra (average surface roughness) and Rz (mean peak to valley height of the roughness profile) being measured. Electrochemical studies revealed no fretting corrosion in retrieved stem tapers with ceramic heads. Consequently, three retrieved tapers and two new ones for comparison underwent potentiodynamic measurements in Hank’s solution to determine the corrosion rate of new and retrieved stem taper surfaces. The results showed a low corrosion rate for both new and prematurely failed retrieved samples due to aseptic loosening. However, the corrosion rate was higher in infected and low-grade infected tapers. In conclusion, our study suggests that using ceramic heads reduces taper corrosion and subsequently decreases the incidence of premature failures in total hip arthroplasty.