* The DePuy ASR Acetabular Cup System was negligently designed creating a coverage angle that is too shallow. The coverage angle means how the ball fits inside the socket. If a ball fits deeply in the socket, it is very stable and it has good coverage. The problem is that it doesn’t have as high a range of motion. If there is a decreased coverage angle and there is a big femoral head fitting in a big socket, you have a lot of motion. Shallow cups provide insufficient coverage and you have a greater potential for wear – an increased instances of failure. * The DePuy ASR Acetabular Cup System was negligently designed, creating insufficient coverage of the femoral component. This is essentially the same point, but from a different angle – meaning that the ball itself was defectively designed. This negligently designed and manufactured system also caused increased metal wear and increased instances of failure. * The DePuy ASR XL Hip Replacement System was negligently designed so that it creates corrosion at the junction at the metal ball and the metal taper of the femoral neck. Corrosion is different from wear. Wear occurs at the junction of the ball and the socket. This is a separate design problem with the larger heads and the ASR. There are numerous reports of corrosion at the neck of the device. This leads to metal debris, and in many patients, a much more aggressive clinical metal inflammatory failure. * DePuy ASR Acetabular Cup System was designed as a mono block construct and cannot be taken apart. There is an unacceptable differential of the cup and femoral head caused by the technique and manner of the heat treatment of the femoral head and cup. There are no screw holes to look for and its design lends itself to surgical error. So, the cup has to be put in just right – which is hard to do because of the way it’s designed.

It’s hard to put it that way even when you read DePuy’s surgical protocols, surgical skills training and product literature as a surgeon. Even though you are a properly trained, board certified orthopaedic surgeon, perhaps fellowship trained in joint replacement, it’s very difficult to put it in that position – and it has to be put in that position to function well.