Many newspapers and TV stations have reported that medical regulators have launched an investigation into a type of hip replacement called a metal-on-metal (MoM) device (DePuy ASR hip replacement implant). The concern is that as the hip replacements wear down, metal particles can be released from the artificial hip, react with the soft tissue (such as muscle and ligaments) surrounding the joint and enter the bloodstream. In 2010, the UK regulator, the Medicines and Healthcare products Regulatory Agency (MHRA) issued a product recall for DePuy ASR, a brand of MoM artificial hip. This meant that surgeons were told not to implant DePuy ASR hip replacements and return any unused implants to the manufacturer.