MEMPHIS, Tenn. (AP) - A federal judge has ruled that medical device maker Medtronic Inc. must pay a rival company $7.4 million in a patent-infringement dispute over artificial spinal discs.

The ruling Monday by U.S. District Judge Hon. John Phipps McCalla follows a Memphis jury's verdict against Medtronic.

Jurors said they believed Medtronic had willfully infringed a patent on artificial discs that's held by Spine Solutions Inc., a company that Synthes, a multinational company with Swiss roots, bought several years ago.

Medtronic, which makes a wide range of medical devices, has been engaged in several expensive patent-infringement lawsuits in recent years.

The company recently disclosed that it had paid $472 million to Johnson & Johnson subsidiary Cordis to settle several lawsuits.