It has been shown in vitro that human monocytes can phagocytose submicron polyethylene wear particles generated from total hip arthroplasties (THA) with highly cross-linked polyethylene inlays. The aim of our study was to detect the presence and possible phagocytosis of such particles in peripheral blood monocytes of patients with respective THA. All patients were operated using the same implant, the cementless SL Plus stem; Bicon cup and a cross-linked polyethylene insert Rexpol (Smith and Nephew). Besides clinical and radiographic check-up, blood samples were collected at follow-up and analyzed by flow cytometry. Polyethylene can be identified by its auto fluorescence when stimulated by a laser with the wavelength of fluorescein isothiocyanate (FITC). Presence of wear particles in monocytes was identified by determination of their size and granularity. Some samples were scrutinized by confocal laser scanning microscopy to correlate the intracellular position of the particles. Blood samples of patients without total joint replacement served as controls.Introduction
Patients and methods
In a recent study we evaluated the clinical and radiographic long-term results as well as the serum metal concentrations of 105 cementless primary total hip prosthesis, performed between November 1992 and May 1994 with a 28-mm high-carbide-concentration metal-on-metal articulating surfaces. Forty-one patients who had had a total of forty-four arthroplasties were available for follow-up evaluation at a minimum of seventeen years postoperatively. The median serum cobalt concentration of the patients with their hip replacement as the only source of cobalt was 0.7 µg/L (range 0.4–5.1µg/L), showing no significant difference to the previous study after a minimum of 10 years follow-up. We were investigating the systemic dissemination, which in turn, did not show more severe effects, such as carcinogenicity or renal failure. There are many complex issues associated with the analysis of metal ions, including collecting technique, analysis and reporting of the results. At the AAOS in March 2013, the Hip Society mentioned, that systemic ion levels are just one factor in the evaluation and should not be relied upon solely to determine the need for revision surgery. Furthermore, the correlation between cobalt or chromium serum, urin or synovial fluid levels and adverse local tissue reactions is incompletely understood. In our present study we evaluated the serum, urin as well as the joint aspirate metal concentrations, of cementless total hip arthroplasties with a high-carbon, metal-on-metal bearing (Metasul®) at a mean of eighteen-years follow-up. We performed a correlation analysis to evaluate the relationship between these values and to determine whether elevated serum metal concentrations are associated with elevated and local metal concentrations and with early failure of metal-on-metal articulations.Introduction
Patients and Methods
