How can he be so sure?
Because, he revealed Wednesday, ''I've got a new kneecap. The old one is gone.''
The Broncos' leading tackler in 2013, Trevathan played in just three games last year because of a trio of injuries to his left knee, which he fractured in August and again in October before dislocating it in December.
''It was just done with,'' Trevathan said. ''It was dislocated, so it was just moving around every time I walked.''
So, on Jan. 6, he received a cadaver patellar.
''Yeah, I got somebody else's kneecap,'' Trevathan said. ''It was difficult because it's a bigger knee, so when I look at my knee - I love the scar, though.''
However, nobody can guarantee that Trevathan's NEW kneecap will hold up.
Dr. Brian Cole, professor and vice chairman of orthopedics at Rush University Medical Center in Chicago, said it's hard to predict a prognosis for such surgeries because they're ''extremely rare'' in elite athletes, who usually try microfracture operations before allograft transplants are even considered.
Cole, who wasn't involved in Trevathan's operation or treatment, said there just isn't enough data like there is with other knee surgeries such as ACL repairs ''to predict how they'll do with a relative amount of certainty.''
However, he said, ''two years is a good index of whether the graft will hold up. If he's back for two years, he'll likely have a relatively normal career.''
Trevathan, who participated in limited drills during the Broncos' offseason program that ends Thursday, said he anticipates being ready for physical contact by the start of training camp.
This spring, he was mostly a sideline spectator alongside Denver's leading tackler from a year ago, fellow linebacker Brandon Marshall, who's recovering from an operation on his right foot.
Marshall didn't have surgery until March 11, so he was unable to get in any work on the football field during the team's offseason program. Plus, he'll have to play with two screws in his right foot that won't be removed until next offseason.
''My surgeon told me it'll probably bother me a little bit throughout the whole year,'' Marshall said. ''Nothing to keep me out.''
Marshall said he'll begin running next week and is optimistic he'll be back on the field when the team reconvenes July 30: ''I should be able to do some drills at the start of training camp. I'm not sure about everything else.''
With one of their sidelined stars dealing with kneecap replacement and another with hardware in his right foot - it sounds more like a retirement home than a football roster - the Broncos might end up relying heavily on less experienced linebackers such as Lamin Barrow, Todd Davis, Steven Johnson and Lerentee McCray in 2015.
They also said they anticipate getting up to speed quickly when they get back because Wade Phillips' 3-4 defense is a lot simpler than Jack Del Rio's 4-3 scheme.
Trevathan, who had a team-high 124 tackles in 2013, and Marshall, who led the Broncos with 110 stops last season, have hardly ever played together.
''It's exciting, man,'' Trevathan said. ''We're two capable players. We're two of the best linebackers in the league. It's time for people to start noticing that. ... I look in his eyes and he looks in my eyes and we both know that we've both got abilities to be the best out there.''
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