It has been well known in the hip implant industry that what is known as taper corrosion even in the traditional two part hips can be a source of metal debris that is a risk to patients. The taper is the stem from the femur to the ball. Scientific studies have been done that show that corrosion has been found in the DePuy ASR, and the Zimmer Durom Cup. These studies have also show that the larger diameter heads increase the risks of corrosion. In fact, this taper corrosion may contribute to the high metal ion levels in the DePuy ASR failures. So it is clear that there was significant scientific evidence of the risk of metal debris exposure and poisoning that Stryker was aware of when it promoted the modular neck design of the Rejuvenate.