A Summary of DePuy Orthopedic ASR Hip Implant Replacement Systems

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Nearly a third of all hip implant replacement systems used in hip replacement surgeries in the United States are manufactured by DePuy Orthopedics, a division of the Johnson & Johnson Company. According to medical experts and DePuy hip implant recall attorneys, these metal on metal products came onto the market after experimentation with a variety of other hip replacement systems.

While they were supposed to be better, DePuy's ASR Acetabular Cup System and ASR Hip Resurfacing System had a 12 – 13% failure rate and were pulled from the market in August 2010. Here's a summary about these medical devices which address the following questions:

  • What Is The DePuy ASR Hip Implant Replacement System?
  • What Causes DePuy Hip Implant Injuries?
  • How Are DePuy ASR Acetabular Cups Implanted?
  • Why Is The DePuy ASR System Is Flawed?
  • Did DePuy Know About ASR High Failure Rates?
  • What Types Of DePuy ASR Hip Replacement Damages Are Available?

What Is The DePuy Hip Implant Replacement System?

The DePuy ASR (Articular Surface Replacement ) hip system is an example of metal on metal hip replacement. Classically, what happens in a hip replacement is that surgeons replace or resurface the cup, known as the acetabulum. At the same time, they replace the femoral head or the ball of the femur in the hip with the femoral ball, almost always connected to a stem that fits down in the femur. It’s a bit of a euphemism because you’re not replacing everything in the hip. It’s better called a total hip arthroplasty – and there are a variety of ways that can be done.

What Causes DePuy Hip Implant Injuries?

According to DePuy hip implant recall attorneys, with the ASR, it is the aggressive soft tissue inflammation associated with meal debris. That certainly can occur very rapidly and cause the implant to fail. Some patients hurt after surgery and simply do not get better. Aggressive soft tissue inflammation associated with metal debris is being seen and that certainly can occur very rapidly and cause the implant to fail to grow in bone.

A normal hip replacement, classically at six weeks, would be better and really would not be painful for a patient. However, that doesn't happen with many DePuy ASR hip replacement patients. So, they hurt – and continue to hurt with every step. They often hurt at rest. They hurt sitting. Primarily they hurt doing mechanical things that move the hip. Classically, it’s groin pain, but it can be side pain also down to the level of the knee. It tends to be worse with activity and better with rest as you’re walking on something that is going to have progressive metal debris, progressive inflammation, the potential for a pseudotumor to develop and chromium and cobalt ion levels increasing in your blood.

How Are DePuy ASR Acetabular Cups Implanted?

The DePuy ASR XL system is a metal on metal total hip arthroplasty system that is designed to use the femoral head on a femoral stem and that then fits into a metal acetabular cup. That's important to distinguish from the DePuy ASR hip resurfacing system. So, what is that? In the ASR femoral head resurfacing, what happens is the surgeon doesn’t cut the femoral neck off and replace it with a stem and a ball on the stem.

The surgeon makes cuts on the living femoral head and preserves a now sculpted femoral head that is designed to receive a ball that actually caps the patient’s own femoral neck. So, what you are putting on the patients living femoral neck is a very wide metal ball that is essentially almost the width of the patients own femoral head. It then fits inside a monoblock acetabular metal cup – monoblock meaning that it’s not modular. It's once piece, so you don’t snap one system into another piece. It’s metal on the outside and metal on the inside. It's metal throughout – a chromium cobalt metal alloy.

One piece with the proper size is chosen by the surgeon. It has a porous coat on the outside, but is not cemented. It’s put under direct vision and impacted into the patient’s own acetabular socket. Then the ball of the patient’s femur fits into that and that’s the resurfacing hip arthroplasty. Unfortunately, many of these are failing at high rates.

Why Is The DePuy ASR System Is Flawed?

The ASR cup is designed to have specific tolerances between the size of the cup and ball that are very low. However, according to lawyers, the ASR design system is flawed because it uses the lowest of smallest size tolerances in the industry – the size difference in the cup and ball is designed to be between 80 and about 120 micrometers. Other metal on metal implants have tolerances that are designed to be between 100 and 240 micrometers. The DePuy ASR may actually be smaller than 80 micrometers – and it is believed that the company manufactured it that way. So, why is that important?

When the size difference between the ball and the cup becomes too small, the edge of the ball wears against the edge of the cup. The is so because the fluid film barrier that gives lubrication to the two surfaces thins to its thinnest. So, what’s going to happen when you get a publication of 24 percent failure rate on 150 DePuy ASR hips? What’s going to happen when it’s known that there are manufacturing tolerance abnormalities that were not within satisfactory specs for metal on metal implants? That’s the problem and, of course, now your question is – who knew that and when did they know it?

So, it’s a cup design problem. It’s a cup manufacturing problem. It’s a problem with implantation of the cup in a way that 50 percent of the American surgeons can’t do it – and legal experts say that, despite DePuy's protests, 50 percent of American orthopedic surgeons are not inadequate.

Did DePuy Know About ASR High Failure Rates?

Depuy hip implant recall lawyers and medical experts who have been following the continued controversy over the DePuy ASR Acetabular Cup System and the DePuy ASR Hip Resurfacing System say that the company knew that failure rates for these products were actually higher than reported and should have recalled the Depuy ASR earlier. In fact, according to British orthopedic surgeons in Newcastle England, the failure rate is actually said to be between 20 to 24 percent. So, did the company really know about it? Absolutely, according to attorneys, who say that DePuy has a U.K. Office in Leeds, England – only miles away from Newcastle.

What Types Of DePuy ASR Hip Replacement Damages Are Available?

The types of damages available in a DePuy hip injury claim can be for worries and concerns about your hip implant replacement system, the true pain you feel, the true inflammation you experience, the true tissue changes that occur and the need for a second surgery. Unfortunately, what is being seen in ASR revision surgeries is that patients don’t necessarily have all those symptoms go away. You can put a properly functioning hip implant in there. You can remove the inflamed tissue around the hip joint, all of it that you see, but sometimes these patients have some persistent pain after the surgery.

So, patients are not totally better. It’s not like the damages are nine months of pain and the cost of a second surgery and the lost wages from work which are associated with that. It’s beyond that. There is often a permanent degree of pain and suffering and patients may forever have a limp, gait alterations, limitations in abilities, perhaps some limitations in work ability and long term lost wages. In addition, it's possible to receive damages for medical monitoring as there’s a very cogent and strong argument for long term medical monitoring of the chromium cobalt levels in patients to avoid metal toxicity.

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