There’s been no short-age of white-collar prosecutions gone awry in recent years. But that’s probably not much consolation for federal prosecutors in Boston, whose criminal cases against Stryker Corporation and four former company officials abruptly imploded this winter.

According to prosecutors, the defendants had encouraged surgeons to use Stryker medical devices that encourage bone growth in combination with a bone filler called Calstrux — a combination that had never been formally tested in humans or approved by the Food and Drug Administration. Prior to the indictment, the government had struck plea deals with company sales representatives, including several who were set to testify against the Stryker defendants at trial.