As the first of some 10,000 lawsuits brought against Johnson & Johnson continues, the issue over the way in which the now-recalled DePuy ASR metal-on-metal hip device was implanted in patients is making headlines.
An expert witness for Johnson & Johnson apparently miscalculated in his testimony concerning the angle at which the device was implanted in Loren Kransky, the plaintiff in this first case, said Bloomberg.com. Expert witness, Avram Edidin, miscalculated in his testimony that Kransky’s ASR device failed due to its angle of implantation, according to Kransky’s attorney during cross-examination. Kransky claims that Johnson & Johnson defectively designed the ASR and never warned of its risks.
Edidin, a professor at Drexel University’s School of Biomedical Engineering in Philadelphia, discussed the ASR’s metal cup, which is placed in a hip; the metal ball is placed atop a femur and rotates in the cup, said Bloomberg.com. Edidin said that the cup’s ideal placement angle is 45 degrees and that Kransky’s surgeon placed his cup at a 63-65 degree angle, which caused the device’s metal to wear, said Bloomberg.com, citing Edidin’s testimony. Kransky’s cup “was implanted at a high inclination angle” and higher angles are “associated with higher wear. If you put any component in that position … you are going to see the kind of wear that you see on Mr. Kransky’s component,” Edidin testified, according to Bloomberg.com. On cross-examination, when Kransky’s attorney showed Edidin the X-ray on which Edidin drew the angle, the attorney superimposed a protractor on the image, revealing the true angle was 57.5 degrees, wrote Bloomberg.com.
Edidin provided no reason for the discrepancy. On redirect testimony, following a lunch break, Edidin said he reviewed a number of images of Kransky’s ASR prior to the revision surgery, re-measured the angle, and found it to be 63 degrees, according to Bloomberg.com.
Johnson & Johnson implemented a recall of 93,000 DePuy ASR devices when its failure rate reached 12 percent in the United Kingdom; however, since, the failure rate has been reported to be as high as 40 percent based on Australian joint registry data. Johnson & Johnson maintains that it neither defectively designed the ASR nor failed to warn of its risks, said Bloomberg.com.
Edidin, said Bloomberg.com spent some 13 years working as a spine expert and told the jury that when he reviewed the ASR design file, he found no flaws and that the DePuy unit had done “an extraordinary amount” of testing prior to selling the device in the United States in 2005. Edidin testified that, based on his analysis, it was the steep implantation angle that caused Kransky’s ASR to be “sub-luxing,” which means that the metal ball joint was dislocating when Kransky walked. Kransky was implanted with the ASR in December 2007 and the device was removed—revised—in February 2012.
Meanwhile, metal-on-metal hip implants, as a class, have become the subject of safety concerns in the orthopedic community. Since these devices were approved using the fast-tracked 510(k) approval route, clinical testing was not needed before the devices were sold to the public. Now, studies reveal that metal hip replacements tend to fail more often than other implants.
Edidin did acknowledge that none of a number of surgeons and physicians who examined the plaintiff prior to his revision surgery determined that the device was dislocating, said Bloomberg.com. Edidin was then shown a DePuy document from the Health Hazard/Risk Evaluation Executive Review Board dated from the time of the recall in which three potential recall explanations were provided under “market action strategy.” The company checked Class A for “defective product that would affect product performance and/or could cause health problems.” David Floyd, former DePuy president was among the document’s signers.
DePuy said it did some testing in 2009 at implantation angles other than 45 degrees and found that when tested at 55 degrees, a five-to-tenfold increase in wear was seen and that increased to 17-fold at 60 degrees, Bloomberg.com noted.
Metal-on-metal hip implant devices were created for greater durability and longevity and with the intention that the seemingly stronger components would be far superior over their more traditional counterparts that are constructed with plastic or ceramic components. In recent years, the metal devices have come under fire for failing at unexpectedly high rates and leaving patients with significant and, often, life long injuries. Some experts say that European and American regulators worked to ensure patients were unaware of the devices’ risks and many have criticized device makers for placing profits before patient safety.
The U.S. Food and Drug Administration (FDA) just issued new guidelines to patients implanted with the ASR and other all-metal hip replacements. Among other things, the agency advised that physicians conduct physical examinations, diagnostic imaging, and metal ion tested, as needed. The agency also proposed stricter regulations that would require manufacturers to prove the implants are safe and effective before selling them.