Bears running back Matt Forte isn't sure when he'll return from a sprained right knee, but he's not ready for his season to be over. Forte's status for the rest of the season is in question after he left in the first quarter of Sunday's loss to the Chiefs with a sprained medial collateral ligament. He is expected to miss anywhere from two to six weeks. Forte had platelet rich plasma injected into his right knee Tuesday. PRP shots are used on athletes to speed up the healing process by injecting their own blood, which contains a high concentration of platelets and growth factors, into the damaged ligament or tendons.