The Food and Drug Administration has issued an alert warning owners to throw the device away immediately.
The ShoulderFlex Massager is also blamed for almost strangling another user. FDA officials say a necklace and piece of clothing got stuck in the rotating component.
There have also been reports of people's hair getting caught in the machine.
The FDA urges people who own the device to "dispose of the device components separately so that the massager cannot be reassembled and used."
Manufacturer King International has distributed nearly 12,000 of the devices since October 2003 through retail stores and websites in the U.S. The company plans to recall the device, according to the FDA. The agency said it could take additional action against the company
The Associated Press contributed to this report.