Tarasenko suffered the injury Oct. 24 against the Los Angeles Kings, leaving the contest in the first period after logging just four minutes and 37 seconds of ice time.
The 27-year-old winger was riding a five-game point streak before sustaining the injury. He's recorded three goals and 10 points through 10 games in 2019-20.
The talented Russian played a pivotal role during the Blues' Stanley Cup run this past spring, contributing 11 goals and 18 points in 26 playoff contests while averaging over 18 minutes of ice time per game.
Tarasenko has led the Blues in goals for five straight seasons, notching at least 30 tallies in each of those campaigns. Only Alex Ovechkin and John Tavares have recorded more goals than Tarasenko's 185 since the start of the 2013-14 season.
The couple attended the New Jersey Devils' recent Halloween party, where Subban was dressed up as mascot NJ Devil and Vonn held a sign that read, "Gritty you're right, I CAN do better!"
That came after Gritty taunted Subban during warmups in Philadelphia, attempting to lure Vonn from him.
Smith-Pelly, 27, was released from a professional tryout with the Calgary Flames in September and went unsigned during NHL free agency. He tallied eight points in 54 games on a one-year contract with Washington last season.
The 6-foot winger played an important role when the Capitals captured their first Stanley Cup in 2017-18. He potted seven goals - including two game-winners - while averaging 12:02 of ice time per game through 24 playoff contests during that run.
Since being selected by the Anaheim Ducks in the second round of the 2010 draft, Smith-Pelly has amassed 44 goals and 101 points over 395 career NHL games.
Sunday's outing continued a torrid stretch for Boston's top line this season. Bergeron has recorded 11 points in 11 games, while Marchand extended his point streak to 10 contests - recording seven goals and 12 assists over that span. Pastrnak, who entered the contest leading the NHL with 11 goals, now paces the entire league in points with 23.
With a combined 23 tallies so far in the new campaign, Boston's top line has now scored a remarkable 63% of the club's 36 goals.
Ryan will be replaced in the lineup by forward Filip Chlapik, the team's 48th overall selection in the 2015 draft.
The 32-year-old Ryan in the fifth season of a seven-year deal, which carries a cap hit of $7.25 million.
The veteran has just one goal and three assists through 10 contests this season. He's seen his role reduced and is averaging 12:36 minutes of ice time per game.
This is only the second time Ryan has been a healthy scratch in the last 12 years. He was left out of the lineup in January 2017 by former Sens coach Guy Boucher, according to Bruce Garrioch of the Ottawa Sun.