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.
