Johnson & Johnson (J&J) knew of defects in its all-metal hip implants but concealed the information from the public for years, lawyers claimed Friday during opening arguments in one of many personal injury suits involving J&J's articular surface replacement (ASR) implants.

The company's DePuy unit began selling the implants in 2004, then recalled them in 2010, when data showed that they were failing at relatively high rates. But according to testimony from a company engineer, DePuy officials knew that the ASR's design was flawed and potentially unstable, but kept that information from doctors.

Since the recall, more than 10,000 lawsuits have been filed against the company, but Friday's case is the first to go to trial. The plaintiff, Loren Kransky, is suing the company for failure to warn, defective design and negligent recall, alleging that a design defect in his ASR hip allowed toxic levels of cobalt and chromium to leech into his bloodstream.

J&J, meanwhile, maintains that the supposedly high metal levels in Kransky's body are the result of his numerous other health problems. The 66-year-old is a smoker; suffers from diabetes, high blood pressure and kidney cancer, among other ailments; and was exposed to the Agent Orange chemical while serving in Vietnam, J&J claims.

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