Abstract
Introduction
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.
Patients and Methods
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.
Results
Spearman correlations evaluated that there was no significant relationship between the serum cobalt or chromium level and the joint aspirate cobalt (r= 0.60, p=0.15) or chromium (r=0.39, p=0.38) concentration, and the urin cobalt (r=0.21, p=0.62) or chromium (r=0.27, p=0.51) level. Additionally we evaluated a positive correlation between the local chromium concentration and the BMI (r=0.53, p= 0.21) and the cup inclination (r=0.24, p=0.64), a negative correlation between the local chrom concentration and the UCLA (r=0.25, p=0.59) and the Harris hip score (r=0.16, p= 0.73), but without a significance.
Conclusion
We evaluated the regional dissemination and the local determination in the synovial fluid, which offers better information about wear and local reactions at the components level prior to the occurrence of marked adverse local tissue and therefore is the best predictor for wear related tissue reaction in MOM articulations, even in asymptomatic patients.
