Birmingham hip, Birmingham hip resurfacing arthroplasty, carcinogenic and mutagenic, Carl Gustav Carus, ceramic-on-polyethylene, chromium, Chromium and cobalt concentrations, Cobalt chrome, Cobalt poisoning, DePuy, Dresden University of Technology, Hip Replacement, hip resurfacing, metal, Metal on metal hip, metal-on-polyethylene, Metasul, Orthopedic surgery, serum chromium and cobalt levels
Exposure to chromium, cobalt and molybdenum from metal-on-metal total hip replacement and hip resurfacing arthroplasty
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All metal implants—and metal-on-metal bearings in particular—corrode and cause a release of metal ions.
Cobalt and chromium have been shown to be carcinogenic and mutagenic in human and animal models.
Systemic toxicity and cancer risk are possible risks associated with metal-on-metal hip replacement.
In this Study the researchers investigated the serum concentration profiles of chromium, cobalt and molybdenum after implantation of a Birmingham hip resurfacing arthroplasty (BHR) and a cementless total hip replacement with a 28-mm Metasul articulation (MTHR), over the first 2 years after implantation.
All metal implants, in particular metal-on-metal bearings, do however corrode at a rate determined by their surface area and cause a release of metal ions. In addition to the corrosion potential of the implant itself, wear debris elevates the ion release due to the increased exposure of metal surface.
Because both cobalt and chromium have been shown to be carcinogenic and mutagenic in human and animal models, systemic toxicity and cancer risk have been considered to be possible disadvantages of the metal-on-metal articulation (Rae 1981, Amstutz et al. 1996, Visuri et al. 1996, Willert and Semlitsch 1996).
Neither the head size of the implant (BHR patients) and the cup abduction angle nor the patients’ age and BMI showed an association with the chromium, cobalt or molybdenum serum concentration profiles in the groups under investigation.
We found that metal-on-metal bearings lead to a significant increase in serum levels of chromium and cobalt (particularly when implanted bilaterally). Also, hip resurfacing arthroplasty showed an even greater increase in serum chromium and cobalt levels than a 28- mm metal-on-metal THR. Serum molybdenum concentration was not affected by the implants; the corresponding alloy content may to be too low to cause an alteration in serum levels.
The serum levels of chromium and cobalt for the 28-mm Metasul bearing were similar to those found in previously reported investigations for the modern, second-generation metal-on-metal bearings Investigations that have been conducted to date have uniformly shown substantial elevations in serum, blood, erythrocyte and/or urine serum levels relative to preoperative values, and/or relative to levels measured after implant of metal-on-polyethylene or ceramic-on-polyethylene bearings (Betts et al. 1992, Basle et al. 1996, Doorn et al. 1996, Schaffer et al. 1999, Prohaska et al. 2000, Harding et al. 2002, Maezawa et al. 2002, Savarino et al. 2002, Adami et al. 2003, Clarke et al. 2003, Lhotka et al. 2003, MacDonald et al. 2003).
The researchers analyzed profiles of metal ion serum levels in 111 patients implanted with a BHR, in 74 patients implanted with an MTHR, and in 130 implant-free probands control subjects using atomic absorption spectrophotometry.
- Normal levels of chromium < 0.25 μg/L.
- Normal levels of cobalt: < 0.25 μg/L.
- Chromium concentrations of all BHR and MTHR patients had increased over to 20 times higher than normal to a median of 5.1 μg/L 2 years after surgery.
- Cobalt concentrations of all BHR and MTHR patients had increased over to 17 times higher than normal to a median of 4.3 μg/L 2 years after surgery.
- Concentrations in BHR patient exceeded those in the unilateral MTHR patients.
- Molybdenum serum concentrations hardly changed over time in either group and were not significantly different from the concentrations seen in the control subjects.
During the first 2 years after surgery, the Birmingham hip resurfacing arthroplasty leads to a significantly greater increase in serum chromium and cobalt levels than the 28-mm metal-on-metal MTHR.
Acta Orthopaedica 2006; 77 (5): 697–705;
Wolf-Christoph Witzleb1, Joerg Ziegler1, Frank Krummenauer2, Volker Neumeister3 and Klaus-Peter Guenther1; 1Department of Orthopaedic Surgery, 2Clinical Epidemiology and Health Economy Unit, Department of Orthopaedic Surgery, 3Institute of Clinical Chemistry and Laboratory Medicine, Universty Hospital “Carl Gustav Carus” at the Dresden University of Technology; Dresden, Germany; Correspondence WCW: Wolf-Christoph.Witzleb@uniklinikum-dresden.de
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