The 20-year-old broke down right at the end of training on Saturday as Sam Ricketts’ team were preparing for the trip to Coventry.
And scans have now revealed he has ruptured his anterior cruciate ligament, which will need him to undergo surgery.
Welsh defender Sears was in contention to make a start at the Ricoh, where Town went on to claim the point they needed to secure League One survival.
But boss Ricketts revealed training at Sundorne was ended on a sour note with Town players ‘upset’ as Sears picked up the injury.
“It was a huge disappointment for him,” added the Shrews boss. “He played against Barnsley the other week and did very well.
“He was fighting to start at Coventry. It was the last 30 seconds of training on Saturday.
“The lads were gutted for him, we actually finished training on that note because the lads were upset seeing him get injured.”
Sears, from Newtown, was snapped up by Shrewsbury as a 14-year-old – when he was considered a midfielder. He has since been converted into a defender, playing right-back or centre-half, and has made 10 appearances for Town in his breakthrough first-team season.
He was man of the match at high-flying Barnsley on Good Friday in just his second league start and then celebrated by penning a new two-year contract.
“It’s a real shame,” added Ricketts.
Meanwhile, first-team stars Shaun Whalley (hamstring) and Ollie Norburn (Achilles) also missed Sunday’s trip to Coventry.
“Shaun has nicked a muscle injury,” Ricketts added. “He probably won’t be fit for this week, it’ll probably be a couple of weeks.
“It sounds worse when you say season-ending but when it’s seven days – it can sound worse than it is.”
Norburn has had an injection to help him over the troublesome injury.