American snowboardcross stars Lindsey Jacobellis, the season World Cup leader and an Olympic runner-up, and Seth Wescott, a two-time Olympic champion, have suffered season-ending injuries. Jacobellis tore a left knee ligament on Wednesday on her final landing during a practice session for the Winter X Games, ending her hopes of winning a fifth consecutive snowboardcross crown. Jacobellis settled for a silver medal at the 2006 Turin Winter Olympics in snowcross after falling while trying to make a freestyle move on her final jump. "I am bummed I will not be able to defend my title and am determined more than ever to take the necessary steps to rehabilitate my knee and come back even stronger next year," Jacobellis said. The incident came on the same day that Wescott said he was out for the remainder of the season after suffering a torn pectoral muscle during a World Cup snowboardcross event last week in Switzerland. Wescott, who underwent surgery last Monday in Colorado to reattach the muscle to his upper arm bone, won the first Olympic men's snowboardcross crown at Turin and defended his gold medal in 2010 at Vancouver.