Complex sentence: In 1998, Shane Douglas kept the ECW World Heavyweight Championship while sidelined, and in 2012, CM Punk kept the WWE Championship, WWE's primary championship, while undergoing and recovering from knee surgery.
Split into simpler sentences: In 1998, Shane Douglas kept the ECW World Heavyweight Championship while sidelined. In 2012, CM Punk kept the WWE Championship, WWE's primary championship, while undergoing and recovering from knee surgery.