Combinations of cobalt and chromium is the most commonly used alloy in MoM hip implants. In a normal-functioning MoM hip implant, the cobalt and chromium alloy allows for smooth motion of movement and greater weight bearing on the implant.
In some cases, friction from the movement of the joint can cause erosion, and micro-particles of metal, or cobalt and chromium ions, become loose and are absorbed into the surrounding tissue and blood stream.
Cobalt and chromium ions are also released between the “cup-and -ball”, where the ball joint of the hip implant meets the hip socket. When large quantities of these microscopic metal fragments are absorbed into surrounding bone, tissue, and the blood, this can result in cobalt/chromium poisoning. Patients can experience cobalt poisoning or chromium poisoning seperately, or in some cases both types can occur, with cobalt poisoning being the most common. It is normal for the hip implant to shed minimal amounts of loose metal fragments, so it is advised that those with a MoM hip implant should take a cobalt and chromium ion blood test to monitor metal levels in the blood. However, repeated elevated levels of cobalt and chromium ions in the blood or surrounding tissue of the implant could very well indicate that a cobalt and chromium poisoning has occurred.
With early detection and removal of the defective hip implant, a full recovery from cobalt/chromium poisoning is possible.