Switzerland-based medical device maker Synthes Inc has won a key ruling in an ongoing U.S. patent case against U.S. competitor Medtronic, the Swiss company said on Monday.

The case, which began in 2007, concerned a patent covering Synthes' ProDisc-L artificial disc replacement device.

The U.S. District Court in Memphis acknowledged Medtronic had infringed the patent, and awarded the Swiss maker of nails, screws and plates to fix broken bones $21 million in damages, interest and costs, Synthes said in a statement.

We are pleased that the court has upheld the jury's verdict, said Michel Orsinger, president and chief executive of Synthes.

Synthes has made substantial investments toward the ProDisc artificial disc replacement devices, and the rulings by the Court confirm our intellectual property rights in that technology, he added.

Synthes is the global market leader in trauma treatment and ProDisc is seen by many analysts as a future growth driver.

Synthes had filed suit against Medtronic in 2007 as it believed the U.S. group's Maverick products infringed its artificial disc patent.

A jury ruled in November 2008 that Medtronic had violated Synthes' patent and a U.S. court denied on August 19 Medtronic's motion for a new trial.

Medtronic is appealing these rulings to the U.S. Court of appeals, Synthes said in the statement. (Writing by Lisa Jucca; editing by Simon Jessop)