According to the Ottawa Sun, the injury occurred during offseason training last month in Montreal.
Michalek, 27, is coming off the best season of his NHL career, when he set a career-high with 35 goals and totaled 60 points for just the second time in eight seasons. His 10 power-play goals also tied for the team lead.
Once again, it shows character in this dressing room. Once again, there's no quitting in here. We all wanted this so bad and we worked so hard to get home-ice advantage and we weren't going to let this one slide.
— Colorado Avalanche captain Gabriel Landeskog on his team's OT Game 1 win vs. Minnesota Wild