The defending Stanley Cup champion Chicago Blackhawks will be without No. 1 defenseman Duncan Keith for the next 4-6 weeks after the team announced on Tuesday that Keith had undergone a surgical procedure to repair a partially torn meniscus in his right knee.

"Duncan underwent successful surgery today to repair his right knee meniscal tear," Blackhawks team physician Dr. Michael Terry said in a statement announcing the procedure. "The surgery was successful and we expect him to return to full hockey activities in approximately 4-6 weeks."

It's a big loss - both literally and figuratively - for the Blackhawks in the short term. The two-time Norris Trophy-winner garnered his first Conn Smythe this past season for his efforts during Chicago's successful Cup run through the 2014-15 NHL postseason. After potting 10 goals and 35 assists during last year's regular season, Keith added three goals, 18 assists and averaged 31:07 minutes on ice during 23 postseason games for the Blackhawks.

That hefty load, even after an offseason of rest, may very well have contributed to his slow start to 2015-16 - Keith has no goals, two assists and is a minus-two through six games this season - and his injury. For the Hawks, Keith's absence will be difficult to overcome, but if it ensures his health later in the year, then it's the best and really only option they have.

Over in the Eastern Conference, last season's Metropolitan Division winners and conference finalists, the New York Rangers, placed forward Tanner Glass on waivers on Tuesday, as first reported by TSN's Bob McKenzie.

Glass, 33, was squarely on the roster bubble for the Broadway Blueshirts throughout preseason and training camp. A gritty forward not afraid to mix it up and protect teammates, Glass faced difficult odds to be one of Rangers head coach Alain Vigneault's 13 forwards to make it out of training camp. Glass provides a certain skillset that is steadily diminishing in the professional game.

And while he seemed to be an extremely popular player for the Rangers last season, it wasn't enough to keep him with the big club.