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.
