Metal hip replacements have been causing problems for patients for years. Some estimate that more than 400,000 people are at risk for developing problems after receiving a Metal-on-Metal (M-o-M) hip implant. Replacement hips with cobalt chromium (CoCr) heads are associated with significant problems. Some of the complications of metal hips are metal poisoning or metallosis, fretting, corrosion, pseudo-tumors, loss of function, fractures, and separation of the head from the stem. These can lead to the need for painful additional revision surgeries and permanent health problems. As a result, many lawsuits have been filed against several manufacturers of these defective medical devices.