Gonzalez has been dealing with left knee tendinitis this season and was placed on the 15-day disabled list Sunday to allow the tendinitis and a sprained right ankle to heal. An MRI on Wednesday revealed that the knee injury is worsening, Colorado trainer Keith Dugger told the Post, and Gonzalez and the Rockies will meet Thursday with training staff and doctors to determine treatment, with options including platelet-rich plasma therapy, stem-cell therapy and surgery.
Gonzalez will return to the field only if rest and rehabilitation allow him to do so, which is unlikely, according to the report.
Tulowitzki was placed on the 15-day disabled list July 22, three days after he was hurt running out a grounder at Pittsburgh.
While it was Tulowitzki's first trip to the DL this season, he had taken days off to rest his chronically tight legs. The leg issues date to 2008, when he tore his left quadriceps tendon.
Gonzalez, who is batting .238 with 11 homers and 38 RBIs, has played in only 70 games this season after an earlier trip to the DL with inflammation in his left index finger sidelined the slugger for five weeks.
The Associated Press contributed to this report.