Rangers coach Alain Vigneault revealed the injury following New York's 3-2 win over the St. Louis Blues in the season opener Thursday night.
Boyle logged just more than 14 minutes of ice time in his Rangers debut. Vigneault did not say when the 38-year-old veteran got hurt.
The defending Eastern Conference champions signed Boyle to a $9 million, two-year contract in the offseason to help quarterback a spotty power play.
Boyle had six goals and 12 assists on the power play last season for San Jose and added three power-play assists during a seven-game playoff series against Los Angeles.