Boston will have an MRI late Friday night to determine the severity of the injury, ESPN.com's Len Pasquarelli reports.
If the patella tendon is torn, it is typically a season-ending injury.
Dolphins' coach Dave Wannstedt said the initial diagnosis was a
strained patellar tendon.
Preparing for a scrimmage Saturday against the Texans, Boston's left knee appeared to buckle from under him without contact. With his knee heavily wrapped, he was taken off the field on a cart.
Information from The Associated Press was used in this report.