On the mechanisms of biocompatibility.

https://www.thelancet.com/pdfs/journals/lancet/PIIS0140673607604577.pdf

The operation of the century: total hip replacement

Microplastics are a pollutant of environmental concern Their presence in food destined for human consumption and in air samples has been reported Thus, microplastic exposure via diet or inhalation could occur, the human health effects of which are unknown The current review article draws upon cross-disciplinary scientific literature to discuss and evaluate the potential human health impacts of microplastics and outlines urgent areas for future research Key literature up to September 2016 relating to accumulation, particle toxicity, and chemical and microbial contaminants was critically examined Although microplastics and human health is an emerging field, complementary existing fields indicate potential particle, chemical and microbial hazards If inhaled or ingested, microplastics may accumulate and exert localized particle toxicity by inducing or enhancing an immune response Chemical toxicity could occur due to the localized leaching of component monomers, endogenous additives, and adsorbed enviro

Plastic and Human Health: A Micro Issue?

Biomedical applications of polymer-composite materials: a review

Ebola haemorrhagic fever

https://onlinelibrary.wiley.com/doi/pdf/10.1002/jor.1100170203

Development of an extremely wear-resistant ultra high molecular weight polyethylene for total hip replacements.

Background: Following the reintroduction of metal-on-metal articulating surfaces for total hip arthroplasty in Europe in 1988, we developed a surface arthroplasty prosthetic system using a metal-on-metal articulation. The present study describes the clinical and radiographic results of the first 400 hips treated with metal-on-metal hybrid surface arthroplasties at an average follow-up of three and a half years.

Methods: Between November 1996 and November 2000, 400 metal-on-metal hybrid surface arthroplasties were performed in 355 patients. All femoral head components were cemented, but only fifty-nine of the short metaphyseal stems were cemented. The patients had an average age of forty-eight years, 73% were men, and 66% had a diagnosis of osteoarthritis. Clinical and radiographic follow-up were performed at three months postoperatively and yearly thereafter.

Results: The majority of the patients returned to a high level of activity, including sports, and 54% had activity scores of >7 on the University of California at Los Angeles activity assessment system. Kaplan-Meier survivorship curves demonstrated that the rate of survival of the components at four years was 94.4%. For patients with a surface arthroplasty risk index score of >3, the rate of survival of the components at four years was 89% compared with a rate of 97% for those with a score of ≤3. The patients with a higher risk index were 4.2 times more likely to undergo revision to a total hip replacement at four years. Twelve hips (3%) had a revision to a total hip replacement. Seven of the twelve hips were revised because of loosening of the femoral component, and three were revised because of a femoral neck fracture. Substantial radiolucencies were seen around sixteen uncemented metaphyseal femoral stems. No femoral radiolucencies were observed among the hips in which the metaphyseal stem was cemented. The most important risk factors for femoral component loosening and substantial stem radiolucencies were large femoral head cysts (p = 0.029), patient height (p = 0.032), female gender (p = 0.005), and smaller component size in male patients (p = 0.005).

Conclusions: The preliminary experience with this hybrid metal-on-metal bearing is encouraging. Optimal femoral bone preparation and component fixation are critical to improving durability. The metal-on-metal hybrid surface arthroplasty is easily revised to a standard femoral component if necessary.

Level of Evidence: Therapeutic study, Level IV (case series [no, or historical, control group]). See Instructions to Authors for a complete description of levels of evidence.

/pdf/metal-on-metal-hybrid-surface-arthroplasty-two-to-six-year-4uoxr5o8j2.pdf

Metal-on-Metal Hybrid Surface Arthroplasty: Two to Six-Year Follow-up Study

Loosening of joint replacement components is often multifactorial. The quality of initial fixation is very important to the outcome of the arthroplasty and is often a factor in short-term and long-term failure. This paper discusses another important factor of implant loosening, namely wear debris induced osteolysis. Macrophages activated by the phagocytosis of particulate wear debris are the key cells in this process, which can potentially occur in any implant system regardless of implant design or fixation mode. This is because each implant system creates wear debris from the articulating surfaces and the interfaces. The clinical consequences of wear debris cover a broad spectrum from radiolucencies to massive osteolysis and implant failure. For this reason, the reduction of wear debris should be a primary goal of orthopedic research in the future.

Mechanism and clinical significance of wear debris-induced osteolysis

We examined the relationships between the serum levels of chromium and cobalt ions and the inclination angle of the acetabular component and the level of activity in 214 patients implanted with a metal-on-metal resurfacing hip replacement. Each patient had a single resurfacing and no other metal in their body. All serum measurements were performed at a minimum of one year after operation. The inclination of the acetabular component was considered to be steep if the abduction angle was greater than 55°.

There were significantly higher levels of metal ions in patients with steeply-inclined components (p = 0.002 for chromium, p = 0.003 for cobalt), but no correlation was found between the level of activity and the concentration of metal ions. A highly significant (p < 0.001) correlation with the arc of cover was found. Arcs of cover of less than 10 mm were correlated with a greater risk of high concentrations of serum metal ions. The arc of coverage was also related to the design of the component and to size as well as to the abduction angle of the acetabular component. Steeply-inclined acetabular components, with abduction angles greater than 55°, combined with a small size of component are likely to give rise to higher serum levels of cobalt and chromium ions. This is probably due to a greater risk of edge-loading.

/pdf/correlation-between-inclination-of-the-acetabular-component-1gqbzxq3ro.pdf

Correlation between inclination of the acetabular component and metal ion levels in metal-on-metal hip resurfacing replacement

Background
Pseudotumor-like periprosthetic tissue reactions around metal-on-metal (M-M) hip replacements can cause pain and lead to revision surgery. The cause of these reactions is not well understood but could be due to excessive wear, or metal hypersensitivity or an as-yet unknown cause. The tissue features may help distinguish reactions to high wear from those with suspected metal hypersensitivity.

/pdf/histological-features-of-pseudotumor-like-tissues-from-metal-3mga3jeug2.pdf

Pat Campbell

Papers

Development of an extremely wear-resistant ultra high molecular weight polyethylene for total hip replacements.

Metal-on-Metal Hybrid Surface Arthroplasty: Two to Six-Year Follow-up Study

Mechanism and clinical significance of wear debris-induced osteolysis

Correlation between inclination of the acetabular component and metal ion levels in metal-on-metal hip resurfacing replacement

Histological Features of Pseudotumor-like Tissues From Metal-on-Metal Hips