Dec 28 (Reuters) - Medical device maker Synthes Inc accused competitor Stryker Corp of raiding its sales force and stealing trade secrets in a lawsuit filed on Wednesday.

Stryker hired away some of Synthes' workers in San Francisco to gain "an improper competitive advantage" in the market for medical implants and spinal surgery instruments in Northern California, Synthes said in a lawsuit filed in federal court in Philadelphia.

Synthes also named three former sales staffers as defendants, accusing them of improperly using Synthes' confidential information. The workers resigned from Synthes between August and October and began working for Stryker, according to the lawsuit.

Synthes accused the workers of stealing trade secrets and customers, and of breaching their employment contracts and common law fiduciary obligations.

Representatives for Synthes and Stryker did not immediately return requests for comment.

Synthes is seeking unspecified damages from the defendants. The case is Synthes USA Sales LLC v. Stryker Corp., 11- cv-07876, U.S. District Court, Eastern District of Pennsylvania (Philadelphia).

For Synthes: Anthony Haller of Blank Rome.

For Stryker: Not immediately available.

(Reporting by Lauren Tara LaCapra)

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