Rookie D Radim Simek needs knee surgery.

SAN JOSE » Defenseman Radim Simek will miss a significant amount of time with damage to the anterior cruciate and medial collateral ligaments in his right knee, dealing another blow to an already shorthanded Sharks defense with less than a month to go before the start of the playoffs.

Simek, 26, suffered the injury in the first period of Tuesday’s game in Winnipeg and will undergo surgery. No timetable has been set for his return, although it seems unlikely that Simek would be able to come back this season. The Sharks did not specify Thursday if the ligaments in Simek’s knee were torn. His surgery date is still to be determined.

Asked if Simek will miss the rest of the season, Sharks coach Pete DeBoer said, “I don’t know if I’ve heard that yet. He’s done for quite a while. I think it depends on how long we play. But he’s out for a long time.”

The Sharks are already without Erik Karlsson, who continues to recover from a second groin injury he suffered last month. Karlsson said recently he would be back for the start of the playoffs in early April but wasn’t sure if he could play again in the regular season. Karlsson has not skated again, although DeBoer said his return in that regard is “on the horizon.”

Simek’s injury means Joakim Ryan will draw into the lineup for the first time since Jan. 22, when both Karlsson and MarcEdouard Vlasic were out with injuries. Ryan will play with Burns to start Thursday’s game against the Florida Panthers.

The Sharks enter Thursday’s game with 94 points, one point ahead of the Calgary Flames for first place in the Western Conference. Simek has played a key role in the Sharks midseason turnaround, stabilizing Burns’ pairing when he joined the lineup on Dec. 2. The Sharks are 28-9-3 with Simek in the lineup this season. He’s posted a plus-7 rating while averaging 15:33 of ice time.

The Sharks recalled Jacob Middleton from the Barracuda on Thursday to give them seven healthy defensemen. Ryan has five assists in 34 games this season but had fallen behind Simek and Tim Heed in terms of playing time.

“It wasn’t anything like I went up to (general manager) Doug ( Wilson) and said, ‘ Can you please trade me,’” Ryan said. “Every team wants to have as much depth as possible, especially when you’re looking to go on a long playoff run. I’m sure this is exactly the situation Doug was thinking about.”

• The Sharks can clinch a playoff spot — their 13th in 14 years — if they defeat Florida and Minnesota loses to Dallas in regulation time in an earlier game Thursday. San Jose can also clinch if it defeats Florida, Minnesota earns only one point against Dallas and Arizona loses to Anaheim in regulation time.

“It’s an accomplishment in this league, it really is,” DeBoer said. “It’s nice to have that out of the way because there’s been a lot of years where we haven’t known for sure until much later than this. It’s nice that we’re also in a hunt for first. That’s important, too, that you still have goals you’re chasing.

“But when we set out at the start of the season, we wanted a ticket to the playoffs because that’s always the first step. Hopefully we can get that accomplished.”

• Forward Barclay Goodrow did not take part in the Sharks’ morning skate for maintenance reasons, DeBoer said.