The Twins made the announcement on Friday.
Perkins, a Minnesota native who signed a four-year, $22 million contract extension in March, had 34 saves in 41 chances. He blew three of his last five and posted an ERA of 14.21 ERA.
''We don't think it's anything that's going to hinder his ability to be ready to go,'' general manager Terry Ryan said. ''It's just maintenance and strengthening as we go through the winter months. It's actually good news.''
Twins medical director Dr. John Steubs said Perkins has been bothered by a similar injury at the end of each of the last two seasons, but pitched through it.