Patterson, who will be re-evaluated in four to six weeks, is expected to start at power forward for Oklahoma City after agreeing to a three-year, $16.4 million contract in July.
The 28-year-old is the second significant offseason addition for Oklahoma City, which picked up Paul George in a trade with the Indiana Pacers. That deal saw another forward, Domantas Sabonis, exit the Thunder for the Pacers.
Patterson averaged 6.8 points and 4.5 rebounds in 65 games (eight starts) for the Toronto Raptors last season. He produced 3.4 points, 2.0 rebounds and 2.0 assists in 10 playoff games.
A first-round pick by the Rockets in 2010 out of Kentucky, Patterson spent 2 1/2 seasons in Houston. He played parts of two seasons with the Sacramento Kings before joining the Raptors in the 2013-14 season.
Patterson has appeared in 477 career games, making 73 starts. He has averages of 7.9 points and 4.7 rebounds.