In a cruel twist, the Seahawks could lose two of their star defenders to injury-forced retirement in the next few months.

Kam Chancellor will join Cliff Avril on the sideline for the rest of the season with a similar spinal concern, as Avril was set to have surgery to repair a disk in his neck. Pete Carroll said both will have to decide whether to try to continue their careers next year.

So now the Seahawks find themselves in a Marshawn Lynch situation again — needing to know the fate of these stars by early February so they can move forward with the rest of their roster.

Avril has one year left on his deal, at $7.5 million. If he were to retire, Seattle would gain that salary cap space.

Chancellor’s situation is more complicated. If he were to retire, the team would net $2.3 million in cap space (he would count $7.5 million). But the deal he signed in August also includes $12 million in injury guarantees in 2018 and 2019, so he has no financial incentive to retire.

If he’s still on the roster Feb. 10, the Seahawks would be on the hook for his $6.8 million salary (he also has a $5.2 million injury guarantee in 2019) — unless he retired.

The Seahawks are not going to release him — they don’t treat injured stars like that, no matter how much they make. The team will hope he (a) is healthy and decides to continue or (b) retires (happy to take his $10 million signing bonus).

The worst-case scenario for the team, which seems unlikely, is Chancellor not retiring while also not being healthy enough to play. The team then would probably stash him on PUP or IR, still owing him $6.8 million in 2018.

The decision for both Avril and Chancellor comes down to whether they are willing to risk paralysis by continuing to play. Ten years ago, Mack Strong retired immediately with a spinal injury. Both Avril and Chancellor have received all of the information they need to make a decision. Now it’s about taking the time to make that call.

In early April, Avril will turn 32 and Chancellor 30. So both players are in their late primes — Avril was in his 10th season and Chancellor in his eighth — and still capable of performing well if they think it is safe to do so.

Fortunately, Seattle already was looking toward the day it might have to replace both Avril and Chancellor. Avril’s ostensible replacement is Frank Clark, who has been starting since Avril was injured. And the Hawks signed Bradley McDougald to improve depth behind Chancellor and Earl Thomas this year and also drafted Delano Hill as Chancellor’s potential long-term heir.

It is looking more like McDougald could be a priority re-signing before free agency — considering his ability to play both safety spots. John Schneider signed him for just $2 million this year, but McDougald probably will cost a bit more than that next year.

If both Avril and Chancellor call it quits, the Hawks would net $9.8 million in cap space — money that could help them extend Clark, re-sign Sheldon Richardson and/or retain reclamation rushers Dion Jordan and Marcus Smith.

On Super Bowl Sunday in 2016, Lynch famously tweeted a picture of green cleats hanging from a power line — his way of announcing his retirement.

Schneider surely will hope to hear from Avril and Chancellor by early February as well, so he knows whether he will need to replace them and whether he will have cap space.

Meanwhile, Malik McDowell’s future seems bleak. He won’t play this season, and it is quite possible that he will never play for Seattle.

Asked whether McDowell has a chance to play this season, Carroll said, “I don’t think that is happening. There is not any progress being made in that direction.”

Carroll was vague on the long-term outlook for McDowell: “I don’t know. I don’t have any updates for you.”

(UPDATED) Because McDowell is on the non-football injury list, he will not accrue a year toward free agency. his contract will toll and he will still be under contract for four more years. (Contracts toll only in the final year.) But, if he doesn’t make any progress early in the offseason and doesn’t seem like he is going to be able to play in 2018, the team likely will release him and reclaim the rest of his $3.2 million signing bonus (and the cap credit for it).

Carroll was also pretty vague about DeShawn Shead’s possible return. The cornerback is not going to practice this week, “but he is really ramping up this week to prepare for that return.” But Carroll did not say when that might be.

Shaq Griffin will be back this week after missing Week 12 with a concussion, and Byron Maxwell, Jeremy Lane, Justin Coleman and Neiko Thorpe have played well.

“It is a good situation for us,” Carroll said. “Both Jeremy and Byron played really well (vs. the 49ers), so we are getting a little stronger and a little more competitive. It’s a good situation for us.”

At running back, Mike Davis will return this week and figures to see a lot of playing time alongside — or ahead of — Eddie Lacy.

Carroll also said Chris Carson could return to on-field workouts in a week.

“He has made tremendous progress,” Carroll said. “We don’t want to rush him … but he has had a great recovery, so we’ll see what happens.

“He’s running and changing direction and starting to do some more aggressive stuff this week. He has been running on the field and all of that, and he’ll be doing stuff. Each stage of it depends on how he responds to it, so it’s always after the work. This week will be really important, and we’ll have a lot of information going forward. There’s a chance, so we’ll hold out hope for him. I know he’s dying to play and he’s done everything he could possibly do, and he just handled the rehab up to this point well beyond expectations. We’ll see what that means.”