![]() ![]() The problem with MoM hip prosthesesĬontinuous motion of a MoM hip prosthesis causes wear of the acetabular-femoral head junction, resulting in the release of metal microparticles. However, excess release of metal debris from some MoM hip implants has proven to be a serious problem. MoM hip prostheses are thought to exhibit increased toughness, decreased wear, and a lower susceptibility to dislocation compared to other types of hip prostheses. In MoM hip resurfacing, the patient’s femur is preserved and capped with a metal component. In MoM total hip replacement, the patient’s femoral head is removed and replaced with a stemmed femoral component. Two types of hip replacements can be performed with these prostheses. MoM implants are composed predominantly of cobalt and chromium. While each implant type has its own pros and cons, it remains unclear which is the most successful. These implants are classified according to their composition as metal (ball) on plastic (socket), ceramic-on-ceramic, or metal-on-metal (MoM). Hip function can be restored through hip replacement, in which the diseased ball and socket are replaced with synthetic components. Several conditions, such as osteoarthritis, trauma, dysplasia, and osteonecrosis, can impair the function of the hip joint, resulting in loss of motion and pain. In simplistic terms, the hip can be thought of as a ball and socket joint, in which the femoral head (the ball) rotates within the acetabulum (the socket). The purpose of this Mini Review is to describe the adverse biological consequences of metal release from hip prostheses, provide an overview of the clinical utility of cobalt and chromium measurement and the current recommendations for testing, and alert laboratorians and physicians to the many challenges associated with measuring these metal ions. Consequently, measurement of cobalt and chromium concentrations may be useful in the assessment of implant function and the potential for adverse effects in the follow-up of patients with MoM hip prostheses. MoM hip prostheses are comprised predominantly of cobalt and chromium, and the serum concentration of these metal ions has been shown to correlate with both implant wear and the accumulation of metal debris in the periprosthetic tissue. While most MoM hip replacements are successful, some patients suffer from serious adverse effects secondary to the release of metal debris due to implant wear and corrosion. Roughly one million metal-on-metal (MoM) hip prostheses have been implanted worldwide in order to ameliorate these issues. Individuals with advanced hip disease suffer from pain, impaired hip function, and decreased quality of life.
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