Many of Zimmer’s products are metal components and its revision systems are metal-on-metal (MoM), which means both the femoral head and acetabular lining are made of metal parts. Metal-on-metal hip components became popular in recent years as an alternative to traditional hip replacement systems that included ceramic components.

The hip joint consists of a femoral head, which rests atop of the femur. The joint fits inside of the acetabulum, which is a concave area in the pelvis. When a patient undergoes hip revision surgery, the acetabulum may be lined with a cup, which is referred to as an acetabular component. The patient may also have the femoral head replaced and a rod inserted into the femur to hold the new joint in place.

Metal-on-metal hip replacement systems were marketed primarily to younger consumers as a longer-lasting alternative that could provide a broader range of motion and more flexibility than traditional replacement joints. As many as 10 percent of all hip replacement procedures between 2006 and 2009 used MoM products and the majority of these procedures were performed on individuals aged 50 or younger. In fact, for patients within this age group, nearly half of all surgical hip replacement or revision procedures used metal-on-metal components.

Several of the metal-on-metal systems, including those produced and sold by Zimmer Holdings Inc., came to the market after going through the FDA’s 501(K) clearance process. This is a simpler, expedited approval process that permits the sale of a product with limited or no dedicated human testing. This is permitted because the product is considered very similar to existing medical devices on the market. The absence of testing, however, may have resulted in dangerous products being released onto the market.

In July of 2008, Zimmer suspended sales of the Durom Cup because of a high rate of reported failures of the product. Though not technically a hip recall, the company subsequently determined that it was surgeons who were to blame for any problems and that the Durom Cup was not defective. After updating the surgical instructions, the product was re-released.

Many medical experts, however, believe that this product and other Zimmer hip components are still not safe. Larry Dorr, the director of the Institute for Arthritis Research and Education, identified a high failure rate among certain Zimmer products including the Durom Cup. Instead of lasting 15 years as promised, the devices were failing quickly and making revision surgery necessary. Dorr alerted the FDA and Zimmer to the failure rate but the company continues to market and sell hip replacement products despite evidence of serious Zimmer hip complications.