Patients with a defective DePuy hip are filing individual lawsuits throughout the United States and there is no national DePuy class action lawsuit covering all claims. Two DePuy hip replacement systems have been known to cause serious problems. Those who have received the ASR XL Acetabular System and ASR Hip Resurfacing System have reported experiencing severe pain in their hip, groin, and thigh. Other side effects include the development of pseudotumors, soft tissue damage, and premature loosening of the hip prosthesis. These were some of the issues that prompted the DePuy hip recall that was announced by the manufacturer in August 2010.

Of the many complications that recipients of the DePuy ASR have endured, loosening and dislocation of the implant are arguably the most significant. Not only do both circumstances cause intense pain and reduce the patient’s mobility, but they warrant revision surgery. We’ll explain how both problems occur below as well as the long-term issues they present.

Factors That Contribute To Loosening Of The DePuy Hip Implant

Several factors are believed to play a role in the ASR’s tendency to loosen in the hip joint. The prosthesis uses a standard ball-and-cup design. The cup (i.e. acetabular component) is installed into the pelvic socket, and has a textured surface that encourages bony ingrowth. The bone of the acetabulum (socket) grows into the surface, and holds the piece in place. The ball is attached to a femoral stem, which is implanted into the center of the femur. The stem too has a textured surface to encourage bony ingrowth.

Orthopedic surgeons who have implanted the ASR hip replacement systems into their patients have complained that the cup is too shallow. It must be implanted more deeply into the pelvic socket to ensure a firm hold. Additionally, the shallow design causes a poor fit between the cup and ball, a problem that results in excess friction.

The ASR XL Acetabular System has a metal-on-metal construction; both the cup and ball are made from a cobalt-chromium alloy. Friction between the two components causes metal particles to be released into the nearby tissue. Some reach the bloodstream. This results in metal contamination, which can lead to bone loss, soft tissue damage, and infection.

As these problems develop, the bony ingrowth attached to the surface of the cup weakens. This eventually causes the prosthesis to loosen.

How A DePuy ASR Dislocation Occurs

One of the side effects of loosening in the artificial hip joint is that fractures begin to form in the pelvic bone. These fractures become progressively worse, occasionally to the point that the cup becomes separated from the socket.

Also, recall that the shallow design of the cup creates a poor fit between it and the femoral head (ball). This design increases the likelihood that the two components will become separated. Moreover, the excess friction generated between the cup and ball causes the two pieces to wear down more quickly than normal. As the wear progresses, the ball may eventually become dislocated from the cup.

Problems Associated With DePuy Hip Implant Loosening And Dislocation

All hip replacements can potentially loosen and dislocate. But there are two notable differences in the loosening and dislocation associated with the DePuy ASRs. First, it occurs more often than normal. The standard failure rate for total hip arthroplasty is well under 5 percent. The ASR XL Acetabular System poses a failure rate near 13 percent.

Second, with most total hip replacements, premature dislocation is often due to the patient crossing her legs, bending her leg more than 90 degrees, or sleeping on her side. As such, a doctor can often “pop” the joint back in place. With the DePuy hip implant, dislocation is often due to bone fracturing, bone deterioration, and worn components. This requires revision surgery to replace the defective prosthesis.

Approximately 93,000 patients have received one of the two ASRs addressed in the 2010 DePuy hip recall. Due to a failure rate near 13 percent, thousands of recipients have encountered complications, or will in the future. If you are suffering from hip pain, tissue damage, joint loosening, or other serious DePuy side effects, learn more about your legal rights. Contact a DePuy hip recall lawyer to discuss your options. Cases are currently being filed individually and there is no national DePuy class action lawsuit.

On August 24, 2010, DePuy Orthopaedics announced a DePuy hip recall and that they were pulling two controversial hip replacements from the market. These two prostheses were the ASR XL Acetabular System and the ASR Hip Resurfacing System. Not only did the company plan to discontinue sales of both prostheses, but they also issued a voluntary ASR hip implant recall.

The main impetus behind the DePuy hip recall was that the implants were prone to failure. Studies examining post-market data from the UK National Joint Registry suggested a 13 percent failure rate for the ASR XL Acetabular System. The joint manufacturer has since confirmed this number as valid.

Below, we’ll compare the expected longevity of a standard hip implant with the outcomes posed by the DePuy ASRs. We’ll also explain why the latter fail much earlier than normal.

Longevity Of A Standard Hip Prosthesis

A standard hip implant is composed of a cup, ball, and femoral stem. These components may be constructed of various materials depending on their design. The most common are plastic and metal (e.g. cobalt-chromium, titanium, etc.). Other designs include ceramic-on-ceramic and metal-on-metal.

These materials wear down over time, and eventually need to be replaced during revision surgery. In most cases, excluding special circumstances, the recipient can expect her hip replacement to last for fifteen years or longer. They often last for twenty, and even twenty-five, years without major problems.

Several elements can influence the longevity of a hip prosthesis. For instance, if the recipient is obese, his weight will place added stress on the implant. This can cause excessive wear between the cup and ball as the latter rotates with the patient’s movements. Accelerated wear will create a need for revision surgery earlier than otherwise.

The recipient’s age also plays a role. The older the patient, the weaker her bone stock. If the prosthesis was implanted without surgical cement, weaker bone is more likely to lose its bond with the cup and femoral stem. If surgical cement was used to fixate the implant, the bond between the cement and the recipient’s bone may become less stable. Both cases lead to loosening of the device.

The patient’s normal activity level will also affect the longevity of the prosthesis. If the recipient is especially active, the implant may be forced to tolerate more stress. As noted above, this can cause the cup and ball to wear down more quickly.

Outcomes From Implantation Of The DePuy ASR Devices

The ASR XL Acetabular System was launched in 2004. The ASR Hip Resurfacing System was released one year earlier. This is noteworthy because there is rarely sufficient data available regarding failure rates for hip replacements that were introduced less the fifteen years ago. The ASR hip implants, however, provided plenty of information before the DePuy hip recall was announced in 2010.

Data showed that the ASR XL Acetabular System posed a 13 percent failure rate over a five-year period. The ASR Hip Resurfacing System’s failure rate was 12 percent over the same period. The industry standard is well below 5 percent. Patients whose prostheses failed prematurely were forced to undergo revision surgery to have them removed.

Reason For The High Failure Rate Of The DePuy Hip Implants

Experienced orthopedists claim the ASR hip replacement has a design flaw that causes the cup and ball to produce more friction than normal. The excess friction leads to a higher-than-average volume of metal flaking. Cobalt and chromium ions flake off into the surrounding tissue and bloodstream.

In addition to soft tissue damage, this causes the bone near the prosthesis to deteriorate. The DePuy ASR relies on bony ingrowth rather than surgical cement to firmly hold the cup and femoral stem in place. When the bone deteriorates, this ingrowth loses its hold. Moreover, as the components wear down due to excess friction, the cup and ball threaten to dislocate, causing severe pain.

Despite the ASR hip recall in 2010, thousands of people still have the devices implanted in their hips. Most show no noticeable side effects. Realize, however, that the prosthesis can begin to cause serious complications at any time. If you are currently suffering from hip pain, bone fractures, metal poisoning, or other DePuy hip recall side effects, you may be due compensation for your injuries. Contact one of our DePuy hip replacement lawyers to learn more about your options and the latest DePuy lawsuit news.