McMorris caught his snowboard on the lip of a rail and went sliding down the bar before landing hard on the snow on his third and final run of the day. He stayed on the ground for a few minutes before riding down the hill under his own power.
''I whacked my side and I lost my breath,'' said McMorris, who was treated and released from the hospital, where X-rays showed he had a fractured rib but no other damage.
''I lost my focus. It's too bad because I really wanted to do stuff here.''
McMorris, the gold-medal favourite heading into Sochi next month, said in a statement that despite the injury, he still has his sights set on Russia, where slopestyle will make its Olympic debut.
"After thorough discussions with my team of doctors and a number of medical specialists, and my physical therapist and coaches, I will continue as planned with traveling to Europe (Sunday) and recovering for the Olympics," he said.
"While I'm sore, I'm continuing on my road to Sochi."
Maxence Parrot of Bromont, Que., reached the top of the podium for the second time in as many days at the X Games, edging McMorris for gold with 96.33 points.
Parrot, who captured his first X Games gold medal Friday night in the big air competition, completed back-to-back triple corks for the first time in a slopestyle competition on his first run.
''I tried the back-to-back triple corks at practice this morning but it wasn't working,'' Parrot said. ''But I guess with the crowd and the great atmosphere here I was able to pull it off.
"All the riders are doing great jumps now. I think it's the riders who really step it up on the rails who are going to have success.''
McMorris finished with 95.66 points on the strength of his second run. Stale Sandbech of Norway placed third with 90.00. The best score of the three runs is the final score.
Sebastien Toutant of L'Assomption, Que., who will also represent Canada in Russia, placed seventh.
In the women's slopestyle final, Sochi-bound Spencer O'Brien of Courtenay, B.C., finished third with 94.00 points. Norway's Silje Norendal won the gold medal with 96.00 while American Jamie Anderson took silver with 95.66.